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Soil Carbon Sequestration in Grazing Lands: Societal Benefits and Policy Implications
Abstract
This forum manuscript examines the importance of grazing lands for sequestering soil organic carbon (SOC), providing societal benefits, and potential influences on them of emerging policies and legislation. Global estimates are that grazing lands occupy 3.6 billion ha and account for about one-fourth of potential carbon (C) sequestration in world soils. They remove the equivalent of 20% of the carbon dioxide (CO2) released annually into the earth's atmosphere from global deforestation and land-use changes. Atmospheric CO2 enters grazing lands soils through photosynthetic assimilation by green plants, subsequent cycling, and sequestration of some of that C as SOC to in turn contribute to the ability of grazing lands to provide societal (environmental and economic) benefits in every country where they exist. Environmental benefits provided include maintenance and well-being of immediate and surrounding soil and water resources, air quality, human and wildlife habitat, and esthetics. Grazing lands contribute to the economic well-being of those living on the land, to trade, and to exchange of goods and services derived from them at local, regional, or national levels. Rates of SOC sequestration vary with climate, soil, and management; examples and conditions selected from US literature illustrate the SOC sequestration that might be achieved. Public efforts, policy considerations, and research in the United States illustrate possible alternatives that impact grazing lands. Discussion of US policy issues related to SOC sequestration and global climate change reflect the importance attached to these topics and of pending legislative initiatives in the United States. Addressing primarily US policy does not lessen the importance of such issues in other countries, but allows an in-depth analysis of legislation, US Department of Agriculture program efforts, soil C credits in greenhouse gas markets, and research needs.
... We conduct an ex-ante policy evaluation of the potential impact of a new payments for ecosystem services (PES) initiative led by the food and agriculture industry, called the Ecosystem Services Market Consortium (ESMC), on California cattle ranches. Amidst the array of rangeland natural resources (Spiegal et al. 2016, Sala et al. 2017), we examine soil organic carbon (or "soil carbon," for the purposes of this paper) in particular, because of both the growing interest in carbon sequestration on agricultural lands as a climate change mitigation strategy and the vast scale of global rangelands, which hold an estimated one-third of global soil carbon (Follett andReed 2010, Delonge et al. 2014). ...
... On most California rangelands, abiotic variables like precipitation play a stronger role in productivity than biotic factors (Oba et al. 2000, Engler and von Wehrden 2018, di Virgilio et al. 2019. Soil carbon sequestration resulting from management changes varies significantly across regions based on soil moisture (Soussanna et al. 2004), largely due to differences in net primary productivity and residue breakdown (Follett and Reed 2010). As a result, adoption of specific management practices by ranchers on California's arid and semiarid rangelands does not reliably impact carbon cycling (Booker et al. 2013, Briske et al. 2014. ...
... Cultural, economic, and political barriers are also present in carbon sequestration on rangelands (Follett and Reed 2010). A range of factors prevent ranchers from participating in conservation programs or adopting new management practices, including characteristics like social networks, education, values and culture (Chan et al. 2012, Lubell et al. 2013, Brain et al. 2014, Roche 2016, ranch system dynamics (Sayre 2004, Wilmer andFernández-Giménez 2015), the type of public or private organization managing a program (Cheatum et al. 2011), program design (Didier andBrunson 2004, Farley et al. 2017), landowners' production goals (Peterson andCoppock 2001, Lubell et al. 2013), as well as agency staff turnover and paperwork burden (Aoyama and Huntsinger 2019). ...
Governance of global natural resources is increasingly hybrid, with complementary public and private sector initiatives layered on landscapes to improve environmental outcomes. The challenge of polycentric land use governance is alignment of goals across diverse governance mechanisms when agricultural producers, public agencies, and corporations have distinct motivations. This case study of soil carbon governance on California rangelands explores a new payment for ecosystem services (PES) initiative led by the food and agriculture industry, called the Ecosystem Services Market Consortium (ESMC). Applying hybrid governance theory to agricultural lands, we conduct an ex-ante policy evaluation of potential policy impact based on (i) alignment between corporate sustainability goals and ranchers' priorities and (ii) complementarity of the ESMC market with existing public and private policies enabling rangeland conservation. We found corporations developing the PES market to be motivated by carbon insetting, the objectives of which converge with ranchers' goals of preserving soils. Each policy offers distinct benefits and challenges, with synergies around climate change adaptation and soil health. As a new policy tool, carbon markets like the ESMC are positioned to meet demand for soil health financing, support resilience and ranch productivity, and improve ranchers' access to soil health data for adaptive management. Given carbon markets' outcome-based payment structure, we highlight the importance of complementary governance mechanisms that mitigate upfront risk with financial and technical support during the transition period, including Farm Bill cost-share programs and private sector financing tools. This policy evaluation highlights the challenges and opportunities surrounding rangelands soil carbon governance, particularly the trade-offs that ranchers, corporations, and society at large must consider for landscape-scale conservation programs.
... Global concern about the impacts of climate change has drawn attention to the top meter of the world's soils, which holds more carbon than the atmosphere and all terrestrial vegetation combined ( FAO 2017 ). An estimated one third of total soil carbon stocks are stored in rangelands, or lands suitable for grazing by herbivores that are often dominated by grasses, forbs, shrubs, and scattered trees ( Follett and Reed 2010 ;Delonge et al. 2014 ). Within the conterminous western United States, rangelands are one of the most extensive land types ( Spiegal et al. 2016 ;FRAP 2017 ). ...
... The impact of grazing management on soil C sequestration rates is moderated by moisture levels associated with the local soil type ( Soussana et al. 2006 ). In mesic ecosystems, grazing management can augment soil C due to increased net primary productivity (NPP) and breakdown of residue from foot traffic ( Follett and Reed 2010 ). In contrast, in arid and semiarid rangelands, improved grazing management does not have a reliable effect on C cycling, in part because of lower moisture levels ( Booker et al. 2013 ;Briske et al. 2014a ). ...
... Soil texture and structure also influence grazing impacts on soil C, as finely textured soils with higher clay content allow for stronger positive grazer effects ( Bronick and Lal 2005 ;McSherry and Ritchie 2013 ). Although recent research has significantly deepened understandings of the formation and persistence of SOM, it is unclear for how long newly sequestered C remains in the soil after improved grazing management ( Follett and Reed 2010 ;Feng et al. 2016 ). Experts believe that physicochemical and biological environmental factors (e.g., mineral surfaces, microbial activity) play a greater role in the persistence of soil C than the molecular characteristics of organic matter itself ( Schmidt et al. 2011 ;Lehmann and Kleber 2015 ). ...
Approximately one third of California is grazed by livestock, with most forage produced on annual rangelands, the common term for rangelands with a significant annual herbaceous component. Given the state's interest in mitigating climate change and growing public attention on grazing systems that enhance carbon sequestration, we investigate the impact of grazing management on soil carbon cycling on California annual rangelands, drawing on soil science, rangeland management, and policy analysis literature. We conclude that using managed grazing for augmenting soil organic carbon on California annual rangelands presents significant challenges. Challenges include the heterogeneity, biogeochemical characteristics, and nonequilibrium nature of California's Mediterranean region, where ecological site conditions, soil type and texture, and climate moderate carbon sequestration. Enduring unknowns in the science underlying soil carbon and the dearth of relevant California-based studies further obscure the potential climate change mitigation effects of grazing systems. Given this, grazing management on California annual rangelands should not be prioritized as a climate change mitigation strategy, unless it is for the purposes of data collection and research. Alternative climate change mitigation opportunities on these landscapes include preventing rangeland conversion and enhancing soil carbon stocks through the suite of range management practices known to augment soil organic carbon or prevent erosion, including marginal cropland restoration, riparian restoration, organic amendments, and silvopasture. In this review, we argue that single-purpose management is generally not fitting for the diverse portfolio of social-ecological services produced on California's vast and varied rangelands. When assessing the value of grazing systems for augmenting soil organic carbon, policymakers, landowners, and other decision makers should consider the potential impacts on the numerous ecosystem services supported by the landscape. The multidisciplinary method presented in this review provides a critical framework for evaluating the appropriateness of working lands carbon policies as Natural Climate Solutions for climate change mitigation are developed in California and other geographies.
... Carbon dioxide emissions through altered land use were estimated at 2 to 4 Pg year −1 C during the 1990s (Schimel et al., 2001). Consequently, scientific interest in the potential of different land-use options, including grazing regimes (e.g., Follett and Reed, 2010;Giongo et al., 2011), to foster C sequestration and to mitigate global warming has grown in recent decades. ...
... Although numerous studies have analysed the impact of grazing on SOC dynamics, different grazing intensities have rarely been considered ( Cierjacks and Hensen, 2004;Cierjacks et al., 2008), and knowledge of the mechanisms by which grazing affects SOC remains limited (Follett and Reed, 2010;Mayes et al., 2014). Moreover, the Caatinga is one of the least studied and most neglected Brazilian ecosystems (Ministério do Meio Ambiente, 2011;Santos et al., 2011). ...
The Caatinga is one of the largest seasonally dry tropical forests in the world. With an estimated area of 600 000 km2 to 900 000 km2 , it is located in the semi-arid north-east of Brazil. The climate is demanding with constant high temperatures, erratic rainfalls, and regular droughts, resulting in general water scarcity. Moreover, the soils in the Caatinga are usually only of low to medium fertility and often shallow and stony. The water-deficient conditions, paired with poor soils, are severely challenging agricultural practice in the region. As the backbone of agriculture, soils play a crucial role in food production.
Therefore, the overall aim of this dissertation was to sustainably increase the fertility of Caatinga soils on a long-term basis to promote food security and livelihood of the local smallholders. Two important parameters that impact soil fertility were considered: nutrient retention and soil organic carbon (SOC). First of all, the effects of biochar and clay addition on the nutrient retention of an Arenosol were evaluated. Second, the influence of various factors on SOC stocks, in particular grazing, were studied. All research was conducted in the Itaparica region in the state of Pernambuco, Brazil.
For the first thematic part, two locally available and inexpensive soil amendments were selected: a traditionally produced mid-temperature biochar made of the invasive tree species Prosopis juliflora (Sw.) DC and the clayey sediment of a temporarily dry lake. In a batch equilibrium experiment, the sorption of ammonium-N (NH 4+ -N), nitrate-N (NO3- -N), potassium (K+ ), and phosphate-P (PO43- -P) was quantified for substrate mixtures of an Arenosol with increasing shares of biochar and clay, respectively. In a corresponding field experiment using the same substrates, the leaching of NH4+ -N, NO3- -N, and K+ was quantified for two consecutive periods of eight months each by using self-integrating accumulators. Both experiments showed the same tendencies. Biochar addition induced marginal to medium retention of NO3- -N, medium retention for PO43- -P, and medium to strong retention of NH4+ -N. In the field experiment, the biochar showed medium retention of K+ , while it provoked strong K+ release in the batch equilibrium experiment. In contrast, clay addition resulted in the release of NO3- -N and medium to strong retention of NH4+ -N, K+ , and PO43- -P.
Both soil amendments showed the potential to enhance the retention of nutrients and, thus, the fertility of an Arenosol. The nutrient retention capacity of the clay remained relatively stable for the 16 months of the field experiment, whereas the retention capacity of biochar significantly dropped for all nutrients by about half in the second observation period compared to the first. The reason was the comparatively low stability of this particular biochar, causing rapid decomposition under the given climatic conditions. Therefore, for future application, the long-term stability of biochar should be enhanced by higher pyrolysis temperatures.
In the second thematic part of this dissertation, SOC stocks of Caatinga soils were quantified on 45 study plots for the upper 5 cm of the soil profile and greater soil depths down to bedrock. Along a gradient of light, medium, and heavy grazing intensity, the impact of grazing on SOC stocks was assessed. Additionally, the influence of clay content, distance to the nearest permanent water body, several vegetation parameters, depth to bedrock, and altitude on SOC stocks were analysed.
The mean organic carbon content in the area was relatively low with 16.86 ± 1.28 Mg C ha −1 . Heavy grazing significantly reduced carbon stocks in the upper 5 cm of the soil profile but had no significant effect in greater soil depths. Clay content and altitude proved to be the most relevant factors influencing SOC stocks of the total soil profile and the stocks below the upper 5 cm.
In summary, grazing has adverse effects on SOC stocks and, consequently, on the fertility of the soils in the Caatinga. In particular, high grazing intensities should be avoided, and animal stocking rates should be reduced and adapted to sustainable local carrying capacities. Conclusively, based on the outcomes of the conducted research, recommendations for agriculture and future research were made.
... Grassland ecosystems cover about 40% of the earth's land surface (Jia et al., 2006) and store 10%-30% of the global soil organic carbon (SOC; Follett & Reed, 2010). Consequently, changes in grassland SOC would have profound effects on the global carbon (C) balance (Follett & Reed, 2010;IPCC, 2013). ...
... Grassland ecosystems cover about 40% of the earth's land surface (Jia et al., 2006) and store 10%-30% of the global soil organic carbon (SOC; Follett & Reed, 2010). Consequently, changes in grassland SOC would have profound effects on the global carbon (C) balance (Follett & Reed, 2010;IPCC, 2013). Atmospheric nitrogen (N) deposition is a major component of global change that is predicted to cause dramatic changes in grassland soil C storage (Reay et al., 2008;Xu et al., 2020). ...
Changes in soil carbon (C) sequestration in grassland ecosystems have important impacts on the global C cycle. As such, it is important that researchers better understand the underlying mechanisms affecting soil C. Increasing evidence has shown that atmospheric nitrogen (N) deposition can cause dramatic changes in grassland soil C. It remains unclear whether herbivore grazing, a primary means to manage and utilize grassland resources, can regulate the effects of N deposition on soil C, and whether these effects are dependent on plant community diversity.
Here, we examined the joint effects of herbivore grazing and N‐addition on soil organic C (SOC) stocks in two types of communities with low and high plant diversity respectively.
Our results showed that the effects of N‐addition and its combination with herbivore grazing on grassland SOC were inconsistent in the two types of communities. In the low‐diversity community, N‐addition greatly decreased SOC stocks, while grazing significantly increased it. Additionally, the grazing‐induced increase in soil C stocks in the presence of N‐addition was so great that it completely counteracted the significant decline in SOC induced by N‐addition. However, in the high‐diversity community, we observed no effects of N‐addition on SOC and grazing increased SOC only in the absence of N‐addition and had no significant effect in the presence of N‐addition.
Synthesis and applications . Our study suggests that increased N deposition can trigger a remarkable reduction in soil C sequestration in grasslands with low plant diversity, but that herbivore grazing can offset this decline, which may help to mitigate greenhouse gas emissions caused by atmospheric N deposition. As a result, we suggest that moderate herbivore grazing should be considered as an effective grassland management measure for maintaining and improving grassland soil C sequestration as the increasing global changes such as elevated atmospheric carbon dioxide, N deposition and biodiversity losses threat.
... Practice dependent, but a potential C sink is grasslands (Conant et al., 2001;Bennett et al., 2009;McSherry and Ritchie, 2013;Mahanta et al., 2019), however, some results may vary depending on the regions Peri et al., 2017;Villarino et al., 2020;Alvarez et al., 2021). They are the major CO 2 removal agent as they remove around 20% of the emissions derived from the clearing of vegetation and land conversion (Follett and Reed, 2010). Globally, grasslands occupy around 26% of total lands with an assessed storage of 343 Pg C, and they subsidize to one-fourth CS through soils (Mahanta et al., 2019). ...
... As a part of the process, society remains the supreme authority for deciding whether it will invest or design effective policies including C plantings (Bryan et al., 2016), or C credits (Follett and Reed, 2010) or not. But collocation of multipurpose policies (e.g., incentives and complementary levies) is crucial in achieving the desired C within a system. ...
Global land use changes that tend to satisfy the food needs of augmenting population is provoking agricultural soils to act as a C source rather than sink. Agricultural management practices are crucial to offset the anthropogenic C emission; hence, Carbon sequestration (CS) in agriculture is a viable option for reversing this cycle, but it is based on hypotheses that must be questioned in order to contribute to the development of new agricultural techniques. This review summarizes a global perspective focusing on 5 developing countries (DC) (Bangladesh, Brazil, Argentina, Nigeria and Mexico) because of their importance on global C budget and on the agricultural sector as well as the impact produced by several global practices such as tillage, agroforestry systems, silvopasture, 4p1000 on CO2 sequestration. We also discussed about global policies regarding CS and tools available to measure CS. We found that among all practices agroforestry deemed to be the most promising approach and conversion from pasture to agroforestry will be favorable to both farmers and in changing climate, (e.g., agroforestry systems can generate 725 Euroeq C credit in EU) while some strategies (e.g. no-tillage) supposed to be less promising and over-hyped. In terms of conservative tillage (no-, reduced-, and minimal tillage systems), global and DC’s land use increased. However, the impact of no-tillage is ambiguos since the beneficial impact is only limited to top soil (0-10 cm) as opposed to conventional mechanisms. Grasses, cereals and cover crops have higher potential of CS in their soils. While the 4p1000 initiative appears to be successful in certain areas, further research is needed to validate this possible mode of CS. Furthermore, for effective policy design and implementation to obtain more SOC stock, we strongly emphasize to include farmers globally as they are the one and only sustainable driver, hence, government. and associated authorities should take initiatives (e.g., stimulus incentives, C credits) to form C market and promote C plantings. Otherwise, policy failure may occur. Moreover, to determine the true effect of these activities or regulations on CS, we must concurrently analyze SOC stock adjustments using models or direct measurements. Above all, SOC is the founding block of sustainable agriculture and inextricably linked with food security. Climate-smart managing of agriculture is very crucial for a massive SOC stock globally especially in DC’s.
... Farms that produce milk and meat from grazed cows using low levels of external inputs may more easily convert to organics (Solorio et al., 2016) and achieve sustainability Diez-Unquera et al., 2012;Aimee et al., 2013;Escribano et al., 2015), and furthermore contribute to a variety of products and environmental services (Follett and Reed, 2010;Gerber et al., 2013;McGahey et al., 2014), especially when cows graze in traditional or innovative SPS with high levels of biodiversity. In such systems, cows may produce twice the milk as those grazed in grasslands in monoculture -aside from meat, fiber, manure, work animals, timber, and firewood -with minimal use of external inputs (Solorio et al., 2016), as occurs in our study area. ...
... Therefore, as compared to conventional grasslands in monoculture, SPS more greatly benefit society from the farm and local levels to the landscape and global levels (Shibu, 2009). As SPS involve intensive management -consisting of a high density of woody fodder plants -and high use of manual labor to compensate for reduced use or absence of external inputs, they preserve small farmers' livelihoods by creating employment (Garrity, 2004;Aguilar et al., 2012), thereby contributing more to farmers' economic well-being than conventional treeless grazing systems due to their greater biodiversity, as well as productivity of fodder and animal products (Follett and Reed, 2010). The animals' diet which is based on grazing on herbaceous and woody species in SPS e which are often integrated with agricultural crops, use of local breeds, and veterinary prevention and care and reproductive techniques that meet organic regulations -contributes to animal well-being, food safety, and cleaner production and sustainability in general given that they are based on low use of external inputs and fossil energy (IFOAM, 2018). ...
This study characterizes technical and economic aspects of conventional dual-purpose (milk and meat) cattle raising in the humid tropics of Chiapas, Mexico and evaluates the potential for converting these farms to organic-or clean-production. An organic livestock raising conversion index with 10 indicators and 37 variables was used. Data was obtained through direct observation and a questionnaire applied to 50 farmers. Through a Cluster analysis (C), we classified Livestock Production Units (LPU) into three groups (p<0.05). The highest values (p<0.05) for the technical-economic indicators as well as ICOGAN were found for the LPU of C3, followed by those of C2 and finally, C1. All LPU evaluated scored very low for the indicators "veterinary prevention and care" and "ecological farm management". The LPU of all three C scored high for the indicators "breeds and reproduction" and "soil fertilization". In order for the LPU to increase their levels of sustainability and be certified organic, there is a need to strengthen farmer's abilities in techniques of ecological production and management through technical advisory and assistance as well as permanent financial support. Furthermore, there is a need for all social actors involved to have a sense of co-responsibility for and be committed to the organic conversion process as well as a need for significant changes in state and federal cattle raising policies.
... According to Aboagye et al. [96], legume fodder could reduce enteric methane emissions by ruminants, as well as tannins, the secondary metabolites particularly abundant in legumes plants, which help control enteric methane emissions [97,98]. Grazing allows for offsetting, at least partially, the greenhouse gas emissions produced by cattle breeding, because it captures organic carbon in the soil for a few years [99][100][101]. ...
The Noble Method® has been successfully introduced in the last few years in Italy and in some foreign countries. This novel livestock management provides, among other rules, a high forage/concentrate ratio, no use of silage and supplements, no GMOs and the availability of outdoor paddocks. One of the goals is to achieve high-quality milk in terms of nutritional properties. Other benefits have been reported; amongst them, the forage/concentrate ratio of the diet was shown to reduce the amount of methane produced by animals, also, the system provides economic benefits, mainly for small breeders, in terms of the sustainability and market placement of milk. Thus, the method represents a sustainable approach to improve the production and the supply chain, from the land to the final product. In this review, the most recent studies on Noble Method® are depicted, showing that, besides the nutritional proprieties of dairy products, the method is able to improve animal welfare, human health and environmental sustainability, thus falling within a “One Health” approach.
... The feeding preferences of herbivores alter the dominant vegetation species in grassland communities (Koerner et al., 2018). Grassland biomes store 10%-30% of global soil organic carbon, and grazing and global climate change are essential factors in grassland carbon dynamics and the global carbon process (Follett and Reed, 2010;Zhou et al., 2019). Meta-analyses showed that soil carbon content increased under light grazing in the subsoil layer (>20 cm), while it decreased on the topsoil under moderate and heavy grazing. ...
Livestock grazing has a significant impact on the biodiversity of nature grassland ecosystems, which is mainly regulated by climate factors. Soil microbes are essential components of biogeochemical cycles. However, the coupling effects of grazing with MAT (mean annual temperature) and MAP (mean annual precipitation) on soil microbial communities remain inconsistent. Our study considered the various climates in four grasslands as natural temperature and precipitation gradients combined with grazing intensity (GI). We collected and analyzed vegetation and soil physiochemical properties from four grasslands. Our results showed that climate factors (CF) changed β diversity of soil bacteria and fungi while grazing intensity and their interaction merely affected fungi β diversity. Furthermore, climate factors and grazing intensity impacted changes in vegetation and soil physiochemical properties, with their interaction leading to changes in EC and MBC. Our analysis revealed that climate factors contributed 13.1% to bacteria community variation while grazing intensity contributed 3.01% to fungi community variation. Piecewise SEM analysis demonstrated that MAT and MAP were essential predictors of bacteria β diversity, which was significantly affected by vegetation and soil carbon and nitrogen. At the same time, MAP was an essential factor of fungi β diversity and was mainly affected by soil nitrogen. Our study indicated that bacteria and fungi β diversity was affected by different environmental processes and can adapt to specific grazing intensities over time.
... Grassland ecosystems cover approximately 40% of the terrestrial lands and provide important ecosystem services including carbon (C) sequestration and climate regulation as well as economic and recreational values (Lecain et al., 2002;Lal, 2004;Piao et al., 2009;Wang & Fang, 2009). Global grasslands store 10-30% of soil organic C (SOC) with a sequestration rate of 0.5 Pg C yr À1 and harbor more than 10% of terrestrial biomass C (Follett & Reed, 2010;Qiu et al., 2013). Currently, a majority of grasslands are experiencing overgrazing (Salvati & Carlucci, 2015), which not only threatens the biodiversity and stability of grasslands, but also alters ecosystem structure and functioning, leading to increased C and N losses (Knops & Tilman, 2000;Stavi et al., 2008;Fornara et al., 2011;Liu et al., 2015). ...
Livestock grazing activities potentially alter ecosystem carbon (C) and nitrogen (N) cycles in grassland ecosystems. Despite the fact that numerous individual studies and a few meta-analyses had been conducted, how grazing, especially its intensity, affects belowground C and N cycling in grasslands remains unclear. In this study, we performed a comprehensive meta-analysis of 115 published studies to examine the responses of 19 variables associated with belowground C and N cycling to livestock grazing in global grasslands. Our results showed that, on average, grazing significantly decreased belowground C and N pools in grassland ecosystems, with the largest decreases in microbial biomass C and N (21.62% and 24.40%, respectively). In contrast, belowground fluxes, including soil respiration, soil net N mineralization and soil N nitrification increased by 4.25%, 34.67% and 25.87%, respectively, in grazed grasslands compared to ungrazed ones. More importantly, grazing intensity significantly affected the magnitude (even direction) of changes in the majority of the assessed belowground C and N pools and fluxes, and C : N ratio as well as soil moisture. Specifically,light grazing contributed to soil C and N sequestration whereas moderate and heavy grazing significantly increased C and N losses. In addition, soil depth, livestock type and climatic conditions influenced the responses of selected variables to livestock grazing to some degree. Our findings highlight the importance of the effects of grazing intensity on belowground C and N cycling, which may need to be incorporated into regional and global models for predicting effects of human disturbance on global grasslands and assessing the climate-bio-sphere feedbacks.
... Grazing and global climate change both control grassland C processes, which may lead to a positive or negative climate-biosphere feedbacks (Follett & Reed, 2010;McSherry & Ritchie, 2013). In this study, we found that the effects of grazing on grassland C storage and release overrode those effects of factors associated with global climate change. ...
Predicting future carbon (C) dynamics in grassland ecosystems requires knowledge of how grazing and global climate change (e.g., warming, elevated CO 2 , increased precipitation, drought, and N fertilization) interact to influence C storage and release. Here, we synthesized data from 223 grassland studies to quantify the individual and interactive effects of herbivores and climate change on ecosystem C pools and soil respiration (Rs). Our results showed that grazing overrode global climate change factors in regulating grassland C storage and release (i.e., Rs). Specifically , grazing significantly decreased aboveground plant C pool (APCP), belowground plant C pool (BPCP), soil C pool (SCP), and Rs by 19.1%, 6.4%, 3.1%, and 4.6%, respectively, while overall effects of all global climate change factors increased APCP, BPCP, and Rs by 6.5%, 15.3%, and 3.4% but had no significant effect on SCP. However, the combined effects of grazing with global climate change factors also significantly decreased APCP, SCP, and Rs by 4.0%, 4.7%, and 2.7%, respectively but had no effect on BPCP. Most of the interactions between grazing and global climate change factors on APCP, BPCP, SCP, and Rs were additive instead of synergistic or antagonistic. Our findings highlight the dominant effects of grazing on C storage and Rs when compared with the suite of global climate change factors. Therefore, incorporating the dominant effect of herbivore grazing into Earth System Models is necessary to accurately predict climate-grassland feedbacks in the Anthropocene.
... Grasslands, covering ca. 40 % of the terrestrial lands and storing 10-30 % of the global SOC, play a crucial role in the ecosystem C dynamic (Follett and Reed, 2010;Bai and Cotrufo, 2022). Grazing is a primary land use in grassland ecosystems and a crucial regulator of major C cycling processes (McSherry and Ritchie, 2013;Zhang et al., 2013;Bai and Cotrufo, 2022). ...
Grasslands store 10-30 % of the global soil organic carbon (SOC) and have the potential to mitigate the increase in atmospheric CO2 concentrations. Grazing plays a crucial role in regulating SOC storage in grassland ecosystems. However, the mechanistic understanding of how grazing influences the SOC dynamic still needs to be improved. We investigated how grazing-induced microenvironment changes influence the microbial assimilation of plant litter C and SOC formation from decomposed litter C in a multi-year field experiment, where grazing was simulated with mowing, dung and urine return, and trampling. We incubated 13C labeled litter in PVC collars to trace the microbial assimilation of litter C and the fate of litter C in the SOC after decomposition. While the grazing treatments changed soil properties marginally, mowing decreased above-ground plant biomass, litter mass, plant height, and plant cover (− 12 % to − 79 %). Accordingly, mowing treatment increased the exposure of litter to UV radiation (+38 %) and therefore facilitated the microbial assimilation of litter C (+20 %) and the SOC formation (+15 %). Trampling treatment promoted the transformation of litter C to SOC pools by mixing litter and soil (+34 %). Dung and urea return treatment did not affect SOC formation due to a marginal change in available nitrogen. Collectively, our results suggest that grazing facilitates litter-derived SOC formation by regulating microbial involvement through changes in the microenvironment. Our study indicates that grazing promotes SOC formation from plant litter, which maintains SOC storage in grasslands. Accurate quantification of the contribution of plant C input to SOC pools in different grasslands under various utilization is the next step to better predict SOC dynamics.
... In terms of total area, the countries with the largest grassland area found are the United Kingdom (11 million ha), France (7.6 million ha), Germany (4.8 million ha) and Italy (4.5 million ha) (12). PG potentially contribute to mitigation of climate change by assimilating atmospheric CO2 and sequestering it in the soil depending on climate, soil, and management (13). Improved grassland management by improving grass and herb species, irrigation, liming and fertilisation can increase the annual soil organic carbon (SOC) stocks by 10% (14,15). ...
This study used the ECOSSE model (v. 5.0.1) to simulate soil respiration (Rs) flux-es estimated from ecosystem respiration (Reco) for eight European permanent grassland (PG) sites with varying grass species, soils, and management. The main aim was to evaluate the strengths and weaknesses of the model in estimating Rs from grasslands, and to gain a better understanding of the terrestrial carbon cycle and how Rs is affect-ed by natural and anthropogenic drivers. Results revealed that the current version of the ECOSSE model may not be reliable for estimating daily Rs fluxes, particularly in dry sites. However, it could still be a valuable tool for predicting cumulative Rs from PG. Additionally, the model demonstrated accurate simulation of Rs in response to grass cutting and slurry application practices. The sensitivity analyses and attribution tests revealed that increased soil organic carbon (SOC), soil pH, temperature, reduced precipitation, and lower water table (WT) depth could lead to increased Rs from soils. The variability of Rs fluxes across sites and years was attributed to climate, weather, soil properties, and management practices. The study suggests the need for additional development and application of the ECOSSE model, specifically in dry and low input sites, to evaluate the impacts of various land management interventions on carbon sequestration and emissions in PG.
... § Installation of photovoltaic panels on the roofs of public buildings; § Encourage public institutions and the local population to install solar systems. Update of the urban waste collection scheme § Identification of the gaps in the municipal waste management plan and its dysfunctions for a better revision of the waste management scheme § Diagnosis and inventory of the waste management system in order to highlight the weak and strong points of the current waste management system § Formulation and proposal of better solutions to fill the gaps and correct the dysfunctions in order to improve the whole waste management process § Opting for a waste recovery center rather than a classic landfill center, reducing the fraction of waste buried and increasing the recovery rate § To improve the functioning of the current controlled landfill of Al Hoceima or technical landfill center: To improve the conditions of its exploitation, allowing a continuous covering of the compartments, and a continuous treatment of the leachate § To eliminate the wild points even if they are already reduced in number Capture of the biogas of the STEP of Al Hoceima § Production of electrical energy § Elaboration of a study for the valorization of the sludge of the WWTP § Installation of a methanization and biogas collection unit § Installation of a co-generator for the production of electricity from the collected biogas (Follett and Reed, 2010) Forest cover Establishment of an effective strategy for the sustainable management of forests and forest soils § Combat heavy deforestation; § Increase the potential of carbon absorption; § Fight against the loss of animal and plant biodiversity and soils; § Fight against soil erosion. § Implementation of a management plan for natural and technical risks (including fire); § Setting up a plan for the preservation and reforestation of forest areas; § Setting up a communal program in partnership with the Regional Directorate of Water and Forests for the reforestation and development of the urban forest, especially at the entrance to the city at the level of the hills and mountains linked to the city § Mobilize non-conventional water (stored rainwater, purified wastewater, etc.) for plant irrigation as needed. ...
The present work consists in the realization of an exhaustive inventory of the sources emitting greenhouse gases (GHG) at the level of the city of Al Hoceima located in the North of Morocco, and this, in order to be able to measure the emissions related to the various components of use of the ground, while being based on the guidelines of the Protocol of the Intergovernmental Panel on Climate Change (IPCC) for the inventories of the GHG emissions and by retaining the principal sources in connection with the sectors: energy, agriculture, forestry and waste. More specifically, this exhaustive and transparent inventory has been elaborated in order to establish a state of the art at the level of the city of Al Hoceima allowing to orientate the territorial managers in their choice of priorities to be retained for the reduction of GHG emissions. The necessary data were collected from several local state and private services, under the year 2019, a year before the containment related to the COVID-19. The results obtained show that the main sector producing the most CO2 emissions in the city of Al Hoceima is related to road transport. This sector has produced on average over the year studied, 71.13% of total emissions with an emission quantity of about 147.86 Gg of CO2 equivalent. The second emitting sector is energy, related to the production of electricity, wood and butane gas, which represents 21.47% of total emissions. Following the results obtained at the end of this work, concrete and sustainable solutions have been proposed so that the city of Al Hoceima can take advantage of all the opportunities related to its development and under low emissions.
... Over half of the world's land area is grazed in various ways: in mixed farming systems, ranching, by wildlife and through pastoralism. Pastoralism is practised mainly on the grasslands that cover about a quarter of the world's surface (Follet & Reed 2010). It is also closely associated with mobile herds and with the drylands (WISP 2008, Robinson et al. 2011). ...
... Grassland ecosystems cover approximately 40% of the terrestrial lands West and Post 2002) and provide important ecosystem services such as carbon (C) sequestration (Yang et al. 2019). Global grasslands store 10-30% of soil organic C (SOC) and harbor more than 10% of terrestrial biomass C (Follett and Reed 2010;Scurlock and Hall 1998). In the context of increasing atmospheric CO 2 concentration, grasslands are considered to be potential C sinks under proper management (Lal et al. 2007). ...
Background and aimsGrasslands hold one of the most important soil carbon stocks in the world, which is vulnerable to climate change (i.e. precipitation) and human disturbance (i.e. land-use). This study aimed to investigate responses and mechanisms of soil organic carbon (SOC) decomposition and accumulation to precipitation and land-use in an Inner Mongolian grassland.Methods
Using a randomized complete block design with a split plot, an experiment with land-use regimes (fencing, grazing, and mowing, since 2011) and altered precipitation amount (wet, + 50% precipitation; CT, ambient precipitation; dry, −50% precipitation; since 2016) was conducted to explore their impacts on SOC decomposition (represented by soil heterotrophic respiration and extracellular enzyme activities) and accumulation (represented by SOC and its physical fractions) from samples collected in 2019.ResultsSOC decomposition significantly increased under wet treatment, but decreased under dry treatment. Wet treatment increased SOC accumulation via the increment of mineral-associated organic carbon (MAOC), and vice versa for dry treatment. Precipitation amount may affect soil microbial biomass and activities via alterations of water supply, plant-derived carbon input, and other soil properties, leading to changes of SOC dynamics. Nevertheless, land-use regimes had little influences on SOC dynamics.Conclusions
Compared to land-use regimes, precipitation treatments can significantly change SOC dynamics. Overall, SOC increased under higher precipitation amount, but decreased with less precipitation. We emphasize that the SOC stock in Inner Mongolia temperate grassland may have an unexpectable fast response to precipitation alteration, but more investigation is still needed in longer terms.
... As one of the most widespread ecosystems worldwide, grassland plays a vital role in the terrestrial carbon (C) cycle [1]. Soil is the major C reservoir of grassland, containing about 10-30% of the global soil organic C (SOC) pool [2,3]. Therefore, the changes in SOC pool of grassland may considerably influence the concentration of atmospheric CO 2 , which is a key factor driving global climate change [4]. ...
Known as the “roof of the world”, the Tibetan Plateau hosts the largest pastoral alpine ecosystem in the world. Nevertheless, there is currently no consensus on how soil organic carbon (SOC) stock changes after livestock grazing on the grassland of this region. Here, a meta-analysis was performed based on 55 published studies to quantify the livestock grazing-induced changes in SOC stock (0–30 cm) in grassland on the Tibetan Plateau. The results showed that livestock grazing significantly increased bulk density by an average of 11.5%, indicating that significant soil compaction was caused by livestock grazing. In contrast, SOC content and stock significantly decreased by 14.4% and 11.9% after livestock grazing, respectively. The decline rate of SOC stock was higher in alpine meadow (−12.4%) than that in alpine steppe (−8.8%), but there was no significant difference between the two rates. The SOC stocks decreased by 10.1%, 6.2% and 20.1% under light grazing, moderate grazing and heavy grazing, respectively. The decline rate of SOC stock under moderate grazing was significantly lower than that under heavy grazing. For different livestock types, it was observed that yak grazing significantly decreased SOC stock by 15.3%. Although the decline rate induced by yak grazing was higher than those induced by Tibetan sheep grazing and mixed grazing, no significant difference was detected among them. Similarly, the grazing-induced SOC declines also did not differ significantly among subgroups of grazing season. The positive relationships between SOC stock and plant biomass indicated that the decreased plant biomass was a likely reason for the declined SOC stock under grazing condition. The findings suggested that moderate grazing with Tibetan sheep in the warm season may minimize SOC losses from grazing activities in alpine grassland on the Tibetan Plateau.
... Follet and Reed (2010), in their policy focused meta-analysis, suggested that properly managed grazing can increase CS, especially in marginally productive pasture lands or areas being reclaimed from agriculture. This is especially true as the US is shifting how land is being used (Follett & Reed, 2010). Zhuo et al. (2017) found differences in their meta-analysis in the impact of the intensity of grazing on CS, with light grazing increasing C while moderate and sever grazing reducing the rate of CS. ...
Carbon sequestration is paramount to reducing climate change. Grasslands, representing 40% of all terrestrial area, can serve as a primary sequestration location if optimal management strategies can be realized. This study used system dynamics modeling to examine the temporal dynamics of carbon stocks and flows in response to grass species composition, grazing intensity, and temperature and precipitation changes at the landscape level. While there are other biogeochemical models in existence, they are either meant to model large areas, including globally, or are meant to be at a farm level and have limited plot sizes, limiting the options for rangeland managers to test management strategies in larger areas. The aims included conducting a field study of the rangeland, create an initial model; evaluate how the model responded to grazing, temperature, and precipitation changes; and compare the model outcomes to prior work to test the behavior of the model as the start of validation. This thesis used four plant functional groups (C3 and C4 grasses, forbs, and legumes) as the base groups for the model. C4 grasses were not found in in the field study but served to test whether the model detected changes in sequestration when grassland composition is changed. The results demonstrated an approach of using functional groups in system dynamics modeling to optimize carbon sequestration while accounting for diverse management strategies, as has been seen in other biogeochemical models. The model was aligned with prior field research in terms of carbon sequestration levels. The model was able to note differences in grazing regimes, temperature, and precipitation changes in terms of carbon sequestration. Grazing scenarios showed that while increased grazing impacted aboveground litter, it had little impact on sequestration; there was only a 4% increase in carbon with no grazing, Changes in temperature, up to 3°C, were predicted to increase carbon sequestration by 16% from 0.442 to 0.514 kg*m-2*day-1 while decreases in precipitation, both alone and in combination with increasing temperatures, was predicted to decrease sequestration up to 44%. This has to do with the grassland composition, ii especially as this was a C3 dominated grassland which grows in the winter and early spring and required more water but lower temperatures for growth. Future research should continue model validation, test additional functional groups like shrubs, implement more soil carbon pools and flows and add a nitrogen component to the model.
... Crop management practices that increase long-term C include cultivation of perennial crops and/or cultivation of pastures (Armstrong et al. 2003;Lal 2004;Follett and Reed 2010;Sanford et al. 2012) and applications of organic amendments (e.g., manure, compost) (Zhang et al. 2012;Brar et al. 2013;. Net losses, on the other hand, can result from excessive tillage, overgrazing and fallowing (Hernanz et al. 2009;Maia et al. 2009). ...
Agriculture is under increasing pressure to produce more food with less environmental impacts and in the face of a changing climate. Management practices capable of sequestering soil carbon (C) and improving overall soil health hold promise for sustainable intensification, as well as climate change mitigation and adaptation. As market and policy-based incentives develop to support these practices, however, it is critical that adequate sampling protocols, minimum viable data sets, and thresholds of management responses to soil health indicators are identified across the diversity of cropping systems and edaphoclimatic conditions.
Much of the research into the impacts of agricultural management on soil C and soil health have been conducted in the Midwest, over the short-term, and to a shallow depth. Soil C dynamics and other soil health indicators are strongly influenced by climate and mineralogy, necessitating more research across a range of edaphoclimatic conditions. Further, detectable changes in soil C take decades to accrue, requiring long-term research. Proper accounting of changes in C stocks on a given acreage for climate mitigation strategies and economic incentive programs also necessitates sampling to a sufficient depth (minimum 1 meter or a root-limiting layer).
Using long-term, on-farm interventions, controlling for cropping system, climate and soil type, this work investigates the impact of soil health practices on soil C in surface and subsurface soils, as well as on a suite of physical, chemical, and biological soil properties commonly used to assess soil health. Deep soil cores at a long-term, industrial scale, agricultural research station in a Mediterranean-type climate indicated that 19 years of cover cropping with annual composted poultry manure applications (4t ha-1) increased soil C to a depth of 200 cm by +21.8 Mg ha-1 relative to a -4.8 Mg ha-1 loss under conventional management (Chapter 1). Trends also indicated potential losses of -13.4 Mg ha-1 under conventional management with cover cropping, despite increases of +1.4 Mg ha-1 in the surface 0-30 cm, stressing the importance of deep soil sampling for greenhouse gas accounting purposes.
Continuing the theme of deep soil C, a nearby regional survey of 10+ yr old hedgerows and adjacent cultivated fields across four soil types showed a strong impact of hedgerows on soil C to a depth of 100 cm, with an average difference of 3.85 kg C m-2 (0-100 cm) and few differences across the four soil types (Chapter 2). Most differences occurred in the surface 0-10 cm and the subsoil at 50-100 cm, indicating a dual role of surface management (litter accumulation, reduced disturbance) and deep, woody perennial roots. Soil type differences were only apparent in one of the four soil types, which differed substantially in parent material, mineralogy, and degree of weathering. Soil type did not influence the management effect and may indicate broad potential for hedgerows as a climate mitigation strategy. The magnitude of this strategy is limited, however, by the extent of hedgerows on a given farm/ranch.
Revegetation of field margins with hedgerows also had a positive impact on a broad suite of physical, chemical, and biological parameters (0-20 cm) commonly associated with soil health (Chapter 3). Hedgerow values were greater than cultivated fields for nearly every indicator in the surface 0-10 cm, commonly 2-3 times greater. Fewer, smaller differences were observed at 10-20 cm. Total soil C and N, available C, microbial biomass C, aggregate stability, and surface hardness were some of the most sensitive and least variable indicators of management type. Texture, pH, and bulk density were more indicative of soil type. A composite of variables was necessary to explain most of the variation in the data, indicating the complexity of soil health.
... For instance, expansion of crop land, uncontrolled exploitation of fuel, wood charcoal, construction and inadequate standard of forest management [25] are anthropogenic impacts that reduces the biological diversity and negatively affecting vital ecosystem functions and services that regulate the earth system upon which humans ultimately depend on [50]. Overgrazing is also one of the causes of degradation due to grazing pressure [65] and affects the soil carbon cycling and sequestration potential of the grazing lands [20] and uses as the substantial source of carbon emission. Carbon sequestration is one of the ecosystem services that can be undertaken by vegetation and soil. ...
This study aimed to estimate the carbon sequestration potential and soil properties of the Abijata-Shalla Lake National Park in Ethiopia. The random sampling techniques were used for dead wood, litter, soil, woody trees and herbaceous) under the different grazing pressure. The DBH (> 2cm) and height of woody trees were used for biomass estimation with allometric equation and the dead wood volumes by smallian formula. The specific wood density was used for each species to estimate the total biomass. The high proportion of (45.35%) woody species found in (10-20cm) DBH classes in the highly grazed area and (38.78%) in the low grazed area. The densities of woody trees decrease as the height and the DBH increases in the study area. The overall mean of carbon stock of aboveground, belowground, dead wood and litter were 112.3, 22.5, 6.9 and 0.95 t C ha-1 , respectively. The soil physical properties (sand and silt) and the electric conductivity (EC) PH, Av.p, CEC shows the significance difference (P < 0.05) with grazing pressure and across soil depth. Generally, the overgrazing has negative impacts on the vegetation biomass and the soil quality. Therefore, the sustainable management, such as destocking of livestock, rotational grazing and intervention of community based conservation was suggested to sustain the ecosystem health and enhance the carbon sequestration potentials.
... Soil organic carbon (SOC) is the largest terrestrial organic carbon pool in the terrestrial biosphere (Scharlemann et al., 2014). Grasslands store 10%-30% of the SOC globally and have been reported to sequester carbon in the soil at a rate of 0.5 Pg yr −1 , which accounts for approximately a quarter of the potential C sequestration in soils globally (Follett and Reed, 2010;Qiu et al., 2013). In China, grasslands are widely distributed, covering an area of approximately 4.0 × 10 7 km 2 , and account for approximately 41% of China's total land area . ...
The temperate steppe experienced degradation and desertification as a result of long-term heavy grazing and excessive reclamation. Some major ecological projects, such as the Grain for Green Program (GGP) and Grazing Exclosure (GE), have been implemented to promote ecological restoration in grassland ecosystems. With the goal of carbon neutrality, the effects of the GGP and GE on grassland carbon sequestration need to be further explored. Based on soil data from the second soil survey in the 1980s, a field survey in 2021, and the land-use/land-cover datasets of 2000–2018, we characterized the changes in soil C stock following grazing exclosure, analyzed the effect of GGP on land-use changes and soil C accumulation, and then estimated the overall grassland carbon sequestration in Ningxia on the Loess Plateau of China. From 2000 to 2018, GE increased the grassland SOCD from 49.60 Mg ha ⁻¹ to 90.71 Mg ha ⁻¹ , and the C stock increased by 65.55 T g. Under the influence of the GGP, 347.62 km ² of cultivated land was converted into grasslands, increasing the grassland soil carbon sequestration by 1.31 T g. Subsequently, the grassland organic carbon storage increased by 66.86 T g, which accounted for approximately 4.26% of the grassland organic carbon storage in the Loess Plateau of China. In the southern Loess hilly area, which experienced high precipitation and low temperatures, grasslands increased by 95.55 km ² ; the average organic carbon density increased 46.95 Mg ha ⁻¹ due to a rate of increase of 2.61 Mg ha ⁻¹ yr ⁻¹ ; and the corresponding values for those in the middle arid zone were 36.25 Mg ha ⁻¹ and 2.01 Mg ha ⁻¹ yr ⁻¹ , with grasslands decreasing by 147.41 km ² . The follow-up policies of the GGP and GE should be implemented and improved according to local conditions to improve the carbon sink and ecological services in grassland ecosystems.
... Globally, grasslands occupy 26% of the ice-free surface of Earth (Scurlock and Hall, 1998). Grasslands store 30% of soil organic carbon (SOC), sequester 0.5 Pg C yr − 1 and possess more than 10% of terrestrial biomass C (Follett and Reed, 2010;Qiu et al., 2013;Zhou et al., 2017). Therefore, studying the C cycle and sequestration clarifies the role of grasslands in farming and animal husbandry, land use, and climate change (Jones and Donnelly, 2004;Liu et al., 2021). ...
Newly assimilated carbon (C) allocated to soil is the main source of C and energy for microorganisms and has a high impact on soil C sequestration. The removal of aboveground plant biomass by grazing may increase, decrease or have no effect on belowground C allocation. Therefore, it is important to understand grazing to optimize the allocation of assimilates between above- and belowground. An in situ ¹³C labeling experiment was carried out in a temperate grassland with three grazing intensities: no grazing, moderate grazing (6 sheep·ha⁻¹) and heavy grazing (9 sheep·ha⁻¹). Eighty-one days after ¹³C labeling, plants under moderate grazing allocated more recently assimilated ¹³C (8.2% of assimilated ¹³C) to shoots than plants under no grazing and heavy grazing (5.5%). Substantially more ¹³C was allocated belowground under moderate grazing, and was mainly stored in roots (11%) and soil (15%), than under no grazing (3.2% in roots and 7.5% in soil) and heavy grazing (4.1% in roots and 6.9% in soil). Moderate and heavy grazing release less ¹³CO2 (15%) through root and rhizomicrobial respiration than no grazing (19%). Without grazing, the decomposition rate of rhizodeposits and their utilization for root and rhizomicrobial respiration (0.22 ± 0.07 day⁻¹) was much faster than that under grazing (moderate grazing: 0.050 ± 0.01 day⁻¹, heavy grazing: 0.065 ± 0.01 day⁻¹). In summary, moderate grazing increases the stock and stability of newly assimilated C in soil by increasing belowground allocation of photosynthates and decreasing CO2 efflux from soil. Therefore, compared to without and heavy grazing (9 sheep·ha⁻¹), moderate grazing (6 sheep·ha⁻¹) may be more suitable for soil C sequestration in temperate grasslands.
... Par ailleurs, l'élevage est aussi reconnu pour sa multifonctionnalité et pour les services écosystémiques auxquels ils contribuent (Huang et al., 2015 ;Dumont et al., 2019). De nombreux auteurs ont montré que l'élevage participe à la fertilisation des sols (Ichinose et al., 2019) et au maintien des prairies qui séquestrent le carbone (Follett et al., 2010 ;Stahl et al., 2016). Plusieurs travaux soulignent par ailleurs que l'élevage contribue à l'entretien d'une mosaïque de paysages, favorisant divers habitats et réseaux trophiques (Herrero et al., 2009;Lemaire et al., 2014). ...
Les transitions agroécologiques des élevages laitiers en territoires agro-pastoraux en France et au Burkina Faso
... More scientific studies aimed at evaluating biophysical processes occurring in soils are necessary to produce more reliable estimates of GHG flux for the United States. To this end, Follett and Reed (2010) identified the need for a national soil-carbon measurement and modeling network. Such a system would improve the understanding of soil processes and enable better GHG and carbon-sequestration estimates. ...
The Energy Independence and Security Act of 2007 (EISA), Section 712, mandates the U.S. Department of the Interior to develop a methodology and conduct an assessment of the Nation’s ecosystems, focusing on carbon stocks, carbon sequestration, and emissions of three greenhouse gases (GHGs): carbon dioxide, methane, and nitrous oxide. The major requirements include (1) an assessment of all ecosystems (terrestrial systems, such as forests, croplands, wetlands, grasslands/shrublands; and aquatic ecosystems, such as rivers, lakes, and estuaries); (2) an estimate of the annual potential capacities of ecosystems to increase carbon sequestration and reduce net GHG emissions in the context of mitigation strategies (including management and restoration activities); and (3) an evaluation of the effects of controlling processes, such as climate change, land-use and land-cover change, and disturbances such as wildfires.
The concepts of ecosystems, carbon pools, and GHG fluxes follow conventional definitions in use by major national and international assessment or inventory efforts. In order to estimate current ecosystem carbon stocks and GHG fluxes and to understand the potential capacity and effects of mitigation strategies, the method will use two time periods for the assessment: 2001 through 2010, which establishes a current ecosystem carbon and GHG baseline and will be used to validate the models; and 2011 through 2050, which will be used to assess potential capacities based on a set of scenarios. The scenario framework will be constructed using storylines of the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emission Scenarios (SRES), along with both reference and enhanced land-use and land-cover (LULC) and land-management parameters. Additional LULC and land-management mitigation scenarios will be constructed for each storyline to increase carbon sequestration and reduce GHG fluxes in ecosystems. Input from regional experts and stakeholders will be solicited to construct these scenarios.
The methods for mapping the current LULC and ecosystem disturbances will require the extensive use of both remote-sensing data and field-survey data (for example, forest inventories) to capture and characterize landscape-changing events. For potential LULC changes and ecosystem disturbances, key drivers such as socioeconomic and climate changes will be used in addition to the biophysical data. The result of these analyses will be a series of maps for each future year for each scenario. These annual maps will form the basis for estimating carbon storage and GHG emissions. For terrestrial ecosystems, carbon storage, carbon-sequestration capacities, and GHG emissions under the present conditions and future scenarios will be assessed using the LULC-change and ecosystem-disturbance estimates in map format with a spatially explicit biogeochemical ensemble modeling system that incorporates properties of management activities (such as tillage or harvesting) and properties of individual ecosystems (such as energy exchange, vegetation characteristics, hydrological cycling, and soil attributes). For aquatic ecosystems, carbon burial in sediments and fluxes of GHG are functions of the present and future potential stream flow and sediment transport and will be assessed using empirical hydrological modeling methods. Validation and uncertainty analysis methods described in the methodology will follow established guidelines to assess the quality of the assessment results.
The U.S. Environmental Protection Agency’s Level II ecoregions map will be the practical instrument for developing and delivering assessment results. Consequently, the ecoregion (there are 22 modified ecoregions) will be the reporting unit of the assessment because the scenarios, assessment results, validation, and uncertainty analysis will be produced at that scale. The implementation of these methods will require collaborations among various Federal agencies, State agencies, nongovernmental organizations, and the science community. Using the method described in this document, the assessment can be completed in approximately 3 to 4 years. The primary deliverables will be assessment reports containing tables, charts, and maps that will present the estimated GHG parameters annually for 2001 through 2050 by ecosystem, pool, and scenario. The results will permit the evaluation of a range of policies, mitigation options, and research topics, such as the demographic, LULC-change, or climate-change effects on carbon stocks, carbon sequestration, and GHG fluxes in ecosystems.
... Some studies have shown that soil management practices that concentrate on reducing soil disturbance and increasing the input and stabilization of organic matter can contribute to carbon sequestration (Mohawesh et al., 2015, Corsi et al., 2012, Follett et al., 2010. ...
Climate change is happening virtually everywhere and is one of the biggest threats facing humanity and life on Earth. As climate change continues across the world, global temperatures are expected to rise, weather events are predicted to become more severe and frequent, and the alteration of ecosystems and wildlife habitats is expected to accelerate. According to the IPCC Working Group Impact, adaptation, and vulnerability report (2007), desert and semi-desert ecosystems, are the most vulnerable ecosystems to climate change impacts due to precipitation fluctuation, future warming trends, and frequent disastrous events. However, there is little information about how climate change may affect the Gobi environment in Central Asia and people’s livelihoods at the regional and local scales.
This research aims to understand how climate change will affect four different systems (atmosphere, biosphere, geosphere, anthroposphere) in Mongolia’s Gobi region. More specifically, the research aims to assess how climate change will affect 1. rangeland vegetation (biosphere) and 2. soil characteristics (geosphere) assess, 3. how herder livelihoods are affected by climate change impacts (anthroposphere) and assess 4. weather and climatic trends over the last 20 years at the local level in the South Gobi region (atmosphere).
To do this, I used a multi-disciplinary approach, including empirical environmental research and both qualitative and quantitative social research. I examined vegetation responses to experimentally simulated climate change (warming, increased and decreased rainfall) and grazing (clipping vegetation) between 2016 and 2019 in Tost Bag in Gurvantes Soum of the South-Gobi, Mongolia. I also assessed how the soil physicochemical properties (soil pH, CaCO3, P2O5, SOC, EC, NO3, bulk density, and dry mass) responded to the experimental climate and grazing simulations. Soil physicochemical properties assessments were conducted at the Soil laboratory of the Institute of Geography and Geo-ecology, Mongolian Academy of Sciences. To assess how local herders were coping with climatic impacts, I conducted 42 semi-structured interviews in the Gurvantes Soum. I discussed with the herders how climatic factors such as dzud and drought could affect their livelihood decision-making, including engaging in informal or illegal mining, becoming a contracted herder, or opening a small business in nearby settlements. Climatic trends for the Gurvantes Soum were assessed by combining information from herder perceptions collected through 32 additional household surveys and meteorological data from a weather station in the Gurvantes Soum. I asked interviewees if they had perceived changes in eight meteorological
variables, including winter temperature, summer temperature, summer precipitation, frequency in intense rain, frequency in drizzle rain, wind speed, number of windy days, and snow cover between 1995 and 2015.
My experimental result revealed that grazing and climate change manipulations reduced vegetation cover by 35-37% (mean: 8.1 gm2) and biomass by 23% (mean: 1.67 gm2) but did not affect species richness (χ2=0.21, df= 3, p=0.98). All targeted plant species responded differently to increasing or decreasing trends to each climatic and grazing treatment and showed species-specific responses with some species increasing and some species decreasing. The climate warming chambers (n=10) showed an increased growth period by an average of 12 days (10-15 days). The soil physicochemical properties assessments showed that the mountain desert steppe landscape in the study area was characterized by sandy loam texture and was alkaline in nature (63.4% of sand content; 21.6% of silt content, and 5% of clay content). This result suggests that the soil was less capable of retaining organic carbon compared to clay-dominated soils. The climate change manipulations showed that an increase in both temperature and precipitation combined with grazing resulted in soil physicochemical properties. Temperature increases of 2 degrees Celsius led to a reduction in organic compounds of the soil and thereby and enrichment of sand in the soil sandy soil characteristics (Anova test: F1,9= 37.08, p>0.05) while a precipitation increase of 50% led to higher soil salinity (Anova test: F2,24= 10.47, p>0.05). In addition, grazing effects had a positive impact on soil organic carbon (Anova test: F1,16=23.69, p< 0.001).
Our semi-structured interviews suggested that livelihood diversification strategies are linked to natural climatic hazards (n= 37, 89%), as well as to political and socio-economic factors (n= 5, 11%). Based on the number of livestock owned, different types of herding typologies were identified in the Gurvantes Soum, including ninja miners (livestock owned n=83.6, SD=58.9), contracted herders (livestock owned n=25, SD=18.7), shared herding (herders take turn to herd each others livestock) (livestock owned n=196, SD=61), herding for others (livestock owned n=321, SD=53.2), true herders herding only their own animals (100% sustain their livelihood by livestock income) (livestock owned n=391, SD=53.2) and rich herders (livestock owned n=784, SD=347). According to the additional household surveys, all herders perceived significant changes in the local weather patterns. Most (94% n= 31) herders reported seasonal shifts, with extreme variations between warm and cool seasons over the last 20 years. Based on focus group discussions, herders agreed that 6 of the 10 climate change scenarios presented would have strong negative impacts on their practices and livelihoods and that none of the scenarios would have positive effects. The meteorological data from the same time period showed an increase in windy days (tau = 0.434, p=0.008) and wind speed (tau = 0.354, p=0.027), a decrease in snow cover (tau = - 0.462, p=0.033), and trends for an increase in the frequency of intense rains (tau = 0.285, p=0.077) and a decreasing in the frequency of drizzle rains (tau = 0.328, p=0.090) although this was significant only at α = 0.10.
My experimental results suggest that the mountain desert steppe zone is at risk of desertification from increasing temperatures and precipitation in the future. The temperature increase was found to decrease vegetation cover and biomass. The experiment also showed that increased precipitation, which was added to simulate intense rains where the total amount of rain increased but the frequency of rainy days decreased, also reduced vegetation cover and biomass. Furthermore, the experiment also showed that temperature increases reduced the organic carbon in the soils and that flush floods increased the salinity. The research also suggested that a range of livestock management strategies could mitigate climate change impacts. The climate change experiment results suggested that light grazing increased the soil’s carbon content, potentially offsetting carbon emissions in mountain desert steppe regions. I recommend further studies to assess vegetation and soil responses to different climate change and grazing strategies (heavy, medium, light).
Another key finding from this study was that people’s livelihoods are impacted strongly by climate change. Rural herders reported a range of coping mechanisms for dealing with changes in the weather and the rangeland, including diversifying their livelihoods. Herders reported that they seek alternative sources of income from activities such as ninja mining when they lose livestock due to events such as natural hazards. The number of ninja miners could be used to indicate and measure climate change impacts on livelihoods in particular areas.
Finally, my results suggest that herder perceptions of climate change appeared to be more focused on rangeland-related changes than the direct meteorological changes themselves. People’s perceptions of climate change are particularly important to provide insights on factors that put their livelihoods at risk directly. Based on my study, herders will be forced to move often with future changes in the climate, leading to rangeland competition among herders. Herder livelihood and herding decisions seemed to be highly responsive to climatic impacts, and their knowledge needs to be incorporated into rangeland and climate change management strategies.
This research helps provide insights on understanding how climate change may impact the mountain desert steppe and the livelihoods of its inhabitants. It also provides
recommendations on how to enhance future ecological and societal resilience to climate change. Traditional knowledge and working closely with herding communities by incorporating their perspectives and views will be essential to develop adapted pastoral management strategies. This work concludes that climate change impacts are influencing multiple aspects of the mountain desert steppe zone, including the climate, local vegetation, soil characteristics, herder livelihoods, and decision making. My research also shows that there is a need for continued research in understanding how climate change is influencing the Gobi environment and putting peoples’ livelihoods at risk. This research provides a foundation for future in-depth assessments.
... Some studies have shown that soil management practices that concentrate on reducing soil disturbance and increasing the input and stabilization of organic matter can contribute to carbon sequestration (Mohawesh et al., 2015, Corsi et al., 2012, Follett et al., 2010. ...
Climate change is happening virtually everywhere and is one of the biggest threats facing humanity and life on Earth. As climate change continues across the world, global temperatures are expected to rise, weather events are predicted to become more severe and frequent, and the alteration of ecosystems and wildlife habitats is expected to accelerate. According to the IPCC Working Group Impact, adaptation, and vulnerability report (2007), desert and semi-desert ecosystems, are the most vulnerable ecosystems to climate change impacts due to precipitation fluctuation, future warming trends, and frequent disastrous events. However, there is little information about how climate change may affect the Gobi environment in Central Asia and people’s livelihoods at the regional and local scales.
This research aims to understand how climate change will affect four different systems (atmosphere, biosphere, geosphere, anthroposphere) in Mongolia’s Gobi region. More specifically, the research aims to assess how climate change will affect 1. rangeland vegetation (biosphere) and 2. soil characteristics (geosphere) assess, 3. how herder livelihoods are affected by climate change impacts (anthroposphere), and assess 4. weather and climatic trends over the last 20 years at the local level in the South Gobi region (atmosphere).
To do this, I used a multi-disciplinary approach, including empirical environmental research and both qualitative and quantitative social research. I examined vegetation responses to experimentally simulated climate change (warming, increased and decreased rainfall) and grazing (clipping vegetation) between 2016 and 2019 in Tost Bag in Gurvantes Soum of the South-Gobi, Mongolia. I also assessed how the soil physicochemical properties (soil pH, CaCO3, P2O5, SOC, EC, NO3, bulk density, and dry mass) responded to the experimental climate and grazing simulations. Soil physicochemical properties assessments were conducted at the Soil laboratory of the Institute of Geography and Geo-ecology, Mongolian Academy of Sciences. To assess how local herders were coping with climatic impacts, I conducted 42 semi-structured interviews in the Gurvantes Soum. I discussed with the herders how climatic factors such as dzud and drought could affect their livelihood decision-making, including engaging in informal or illegal mining, becoming a contracted herder, or opening a small business in nearby settlements. Climatic trends for the Gurvantes Soum were assessed by combining information from herder perceptions collected through 32 additional household surveys and meteorological data from a weather station in the Gurvantes Soum. I asked interviewees if they had perceived changes in eight meteorological variables, including winter temperature, summer temperature, summer precipitation, frequency in intense rain, frequency in drizzle rain, wind speed, number of windy days, and snow cover between 1995 and 2015.
My experimental result revealed that grazing and climate change manipulations reduced vegetation cover by 35-37% (mean: 8.1 gm2) and biomass by 23% (mean: 1.67 gm2) but did not affect species richness (χ2=0.21, df= 3, p=0.98). All targeted plant species responded differently to increasing or decreasing trends to each climatic and grazing treatment and showed species-specific responses with some species increasing and some species decreasing. The climate warming chambers (n=10) showed an increased growth period by an average of 12 days (10-15 days). The soil physicochemical properties assessments showed that the mountain desert steppe landscape in the study area was characterized by sandy loam texture and was alkaline in nature (63.4% of sand content; 21.6% of silt content, and 5% of clay content). This result suggests that the soil was less capable of retaining organic carbon compared to clay-dominated soils. The climate change manipulations showed that an increase in both temperature and precipitation combined with grazing resulted in soil physicochemical properties. Temperature increases of 2 degrees Celsius led to a reduction in organic compounds of the soil and thereby and enrichment of sand in the soil sandy soil characteristics (Anova test: F1,9= 37.08, p>0.05) while a precipitation increase of 50% led to higher soil salinity (Anova test: F2,24= 10.47, p>0.05). In addition, grazing effects had a positive impact on soil organic carbon (Anova test: F1,16=23.69, p< 0.001).
Our semi-structured interviews suggested that livelihood diversification strategies are linked to natural climatic hazards (n= 37, 89%), as well as to political and socio-economic factors (n= 5, 11%). Based on the number of livestock owned, different types of herding typologies were identified in the Gurvantes Soum, including ninja miners (livestock owned n=83.6, SD=58.9), contracted herders (livestock owned n=25, SD=18.7), shared herding (herders take turn to herd each others livestock) (livestock owned n=196, SD=61), herding for others (livestock owned n=321, SD=53.2), true herders herding only their own animals (100% sustain their livelihood by livestock income) (livestock owned n=391, SD=53.2) and rich herders (livestock owned n=784, SD=347). According to the additional household surveys, all herders perceived significant changes in the local weather patterns. Most (94% n= 31) herders reported seasonal shifts, with extreme variations between warm and cool seasons over the last 20 years. Based on focus group discussions, herders agreed that 6 of the 10 climate change scenarios presented would have strong negative impacts on their practices and livelihoods and that none of the scenarios would have positive effects. The meteorological data from the same time period showed an increase in windy days (tau = 0.434, p=0.008) and wind speed (tau = 0.354, p=0.027), a decrease in snow cover (tau = - 0.462, p=0.033), and trends for an increase in the frequency of intense rains (tau = 0.285, p=0.077) and a decreasing in the frequency of drizzle rains (tau = 0.328, p=0.090) although this was significant only at α = 0.10.
My experimental results suggest that the mountain desert steppe zone is at risk of desertification from increasing temperatures and precipitation in the future. The temperature increase was found to decrease vegetation cover and biomass. The experiment also showed that increased precipitation, which was added to simulate intense rains where the total amount of rain increased but the frequency of rainy days decreased, also reduced vegetation cover and biomass. Furthermore, the experiment also showed that temperature increases reduced the organic carbon in the soils and that flush floods increased the salinity. The research also suggested that a range of livestock management strategies could mitigate climate change impacts. The climate change experiment results suggested that light grazing increased the soil’s carbon content, potentially offsetting carbon emissions in mountain desert steppe regions. I recommend further studies to assess vegetation and soil responses to different climate change and grazing strategies (heavy, medium, light).
Another key finding from this study was that people’s livelihoods are impacted strongly by climate change. Rural herders reported a range of coping mechanisms for dealing with changes in the weather and the rangeland, including diversifying their livelihoods. Herders reported that they seek alternative sources of income from activities such as ninja mining when they lose livestock due to events such as natural hazards. The number of ninja miners could be used to indicate and measure climate change impacts on livelihoods in particular areas.
Finally, my results suggest that herder perceptions of climate change appeared to be more focused on rangeland-related changes than the direct meteorological changes themselves. People’s perceptions of climate change are particularly important to provide insights on factors that put their livelihoods at risk directly. Based on my study, herders will be forced to move often with future changes in the climate, leading to rangeland competition among herders. Herder livelihood and herding decisions seemed to be highly responsive to climatic impacts, and their knowledge needs to be incorporated into rangeland and climate change management strategies.
This research helps provide insights on understanding how climate change may impact the mountain desert steppe and the livelihoods of its inhabitants. It also provides recommendations on how to enhance future ecological and societal resilience to climate change. Traditional knowledge and working closely with herding communities by incorporating their perspectives and views will be essential to develop adapted pastoral management strategies. This work concludes that climate change impacts are influencing multiple aspects of the mountain desert steppe zone, including the climate, local vegetation, soil characteristics, herder livelihoods, and decision making. My research also shows that there is a need for continued research in understanding how climate change is influencing the Gobi environment and putting peoples’ livelihoods at risk. This research provides a foundation for future in-depth assessments.
... Moreover, beef farming contributes massively towards carbon sequestration by producing high quality meat while making an efficient use of rangelands that could otherwise store a huge amount of carbon (Broocks et al., 2017). Research exploring the value added by grazing on soil organic carbon storage has reported a remarkable advancement from no impact to over 48.625 kg of carbon per hectare per annum (Follett and Reed, 2010). Furthermore, ruminants efficiently use 80% of South African agricultural land that is only suitable for livestock production, which contributes 40% to the country's agricultural revenue (Oduniyi et al., 2020). ...
An experiment was conducted to evaluate the impacts of graded dietary fiber levels on feed efficiency and carbon footprint in 9 Bonsmara (225 ± 10.0 kg live weight) and 9 Nguni (215 ± 10.0 kg live weight) steers. The steers were aged between 8 and 9 months. Three treatment diets had graded neutral detergent fiber (NDF) levels of 64.3% (high fiber) for Diet 1, 40.4% (moderate fiber) for Diet 2 and 29.9% (low fiber) for Diet 3. Steers were fed respective experimental diets for 90 days and housed in feedlot individual pens. Body weight gain was measured fortnightly to monitor feed efficiency. Methane emissions were measured to ascertain carbon footprint, using a LaserMethane Mini (LMm). Feed intake was enhanced and carbon footprint was reduced in both breeds by a low fiber diet. When methane emissions were expressed as the percentage of feed intake, 17%, 8% and 6% were observed for Bonsmara steers receiving high, moderate and low fiber diets, respectively. On the contrary, Nguni steers emitted 25%, 12% and 13% of consumed feed as methane for high, moderate and low fiber diets, respectively. Nguni steers in all three treatments had better feed conversion ratio than the Bonsmara steers. Additionally, Nguni steers emitted 1% less of consumed moderate fiber diet as methane compared to low fiber diet. Feeding a low fiber diet can be used to reduce carbon footprint while improving feed efficiency of beef steers.
... Grasslands occupy an estimated 3.6 billion ha globally and account for approximately one-fourth of C stored in the world's soils (Follett and Reed 2010), acting as important sinks of atmospheric carbon dioxide (CO 2 ) released from global deforestation and land-use changes (Conant et al. 2017). Agricultural practices that result in soil disturbance (i.e., tillage) impact soil organic C (SOC) accumulation and stability (Cambardella and Elliott 1992;Six et al. 1999), whereas improved grassland management practices that increase above-and belowground biomass production often result in increases in SOC (Conant et al. 2001(Conant et al. , 2017Allard et al. 2007;Ammann et al. 2007). ...
Soils under grasslands contribute significantly to terrestrial carbon (C) and nitrogen (N) pools, and grassland management practices directly impact pool size through effects on plant biomass. Our objective was to quantify above and belowground plant biomass and soil C and N accumulation for year-round forage systems based on N-fertilized grasses (GN; 290 kg N ha−1 yr−1) or legume-grass mixtures (LG; 30 kg N ha−1 yr−1) when grazed or harvested for hay. Soil C and N accumulation (0–0.4 m) were evaluated before and 6 yr after imposing treatments. Average root-rhizome mass did not differ for GN and LG systems (3690 and 3020 kg OM ha−1, respectively). Aboveground residual biomass was 55% greater for GN than LG (4890 vs. 3150 kg OM ha−1, respectively) and 46% greater for grazed than hayed swards (4770 vs. 3270 kg OM ha−1, respectively) at the end of the warm season. Aboveground C and N pools were 70 and 58% greater for GN than LG, respectively. After 6 yr, soil C and N concentration (0–0.1 m) increased 6.7 and 0.8 g C kg−1 and 0.6 and 0.2 g N kg−1, for GN and LG, respectively. Annual C accumulation (0–0.1 m) was 1.3 and 0.2 Mg C ha−1 for GN and LG systems, respectively. Thus, a year-round forage system based on N-fertilized grasses accumulated more plant biomass and surface soil C and N than a legume-grass mixture, with the grass system advantaged by presence of a perennial C4 species and application of moderate to high N fertilizer rates.
... Beyond its economic benefits, MIG is believed to have ecological advantages over other forms of pasture management, such as offering higher forage productivity aboveground Oates and Jackson, 2014) and increased soil carbon (C) storage belowground (Sanderman et al., 2015;Gosnell et al., 2020). The soil C storage potential of MIG is of considerable interest as a means of mitigating climate change (Conant et al., 2001;Follett and Reed, 2010;Teague et al., 2016;DeLonge and Basche, 2017;Teague and Barnes, 2017;Sykes et al., 2020). The ability of MIG systems to achieve ecological outcomes such as C sequestration is also a topic of considerable debate, in part due to inconsistent findings across prior studies (Briske et al., 2008(Briske et al., , 2011McSherry and Ritchie, 2013;Abdalla et al., 2018). ...
Management intensive grazing (MIG), also known as rotational grazing or multi-paddock grazing, is purported to sequester carbon (C) in soils compared to other agricultural management systems. Prior research examining the potential for MIG to enhance soil C has been inconclusive, and past investigations have not addressed whether higher nitrous oxide (N2O) emissions may accompany increases in soil C stocks. Here we examined linkages among MIG, soil C accumulation, and N2O emissions in cool-season, organic pastures of the northeastern United States. We found that pastures under MIG increased soil C concentrations by 11% from 0–15 cm depth but that soil C stocks at all sampled depths did not differ between hayed and grazed fields. We observed a divergent response in soil N to MIG, where both N concentrations and stocks significantly increased and the soil C:N ratio significantly decreased in rotationally grazed pastures. Our results also demonstrated that during the second year of the study, N2O emissions were on average 33% higher in grazed fields and compared to hayed fields. These elevated N2O fluxes in MIG fields may have offset any soil C gains achieved under MIG, as demonstrated by similar climate forcing values (as CO2-equivalents) for hayed and grazed pastures over a 100-year time horizon. The significant variation we detected among farms in soil C and N stocks, soil microbial activity, plant biomass production, and soil greenhouse gas emissions demonstrates that MIG does not have uniform effects across the landscape. Overall, our study demonstrates that care should be taken when promoting management practices that may have unintended climate consequences.
... Grasslands cover more than a third of the earth's terrestrial surface and provide important ecosystem services including carbon (C) sequestration and regulation of the climate, as well as economic and recreational values (Lal, 2004;Piao et al., 2009;Wang and Fang, 2009;Yang et al., 2019). Globally, grasslands contain 10-30% of soil organic C (SOC) with a sequestration rate of 0.5 Pg C yr − 1 and hold more than 10% of terrestrial biomass C (Follett and Reed, 2010;Qiu et al., 2013). This implies that a modest increase in grassland C stock could have a large impact on reducing atmospheric CO 2 concentration, thereby influencing the future climate (Lal, 2004). ...
Livestock grazing is an important driver of the carbon (C) cycle in grasslands and could be a decisive factor determining whether grasslands are a net sink or source of C. However, short-term C dynamics in grassland ecosystems and its response to different grazing intensities remain unclear, especially under field conditions. Here we test the hypothesis that photosynthetic C allocation in the plant-soil system of grasslands is differentially affected by the intensity of grazing that occurred in the prior growing season. We studied the fate of new C assimilates, using a 13 CO 2 pulse-labeling technique, as they move from shoots to roots and soil in vegetation previously exposed to different defoliation (emulated grazing) intensities in two semiarid Mixed Prairie grassland ecosites having contrasting soil textures (sandy vs. loamy). Within 24 h after photosynthetic uptake, 34.5% of the labeled C was translocated out of shoots, with 21% of the labeled C found in the mineral soil. Plant communities treated with high intensity defoliation during the previous growing season had more of the newly fixed 13 C translocate into live roots at both ecosites throughout the 25-day chase period, indicating a higher demand for photosynthetic C by the root system of heavily defoliated plants. Twenty-five days after labeling, 13 C transfer into the top 30 cm mineral soil was consistently greater at the loamy (26% of total 13 C remaining) than at the sandy ecosite (10.4% of 13 C remaining). We conclude that conditioning with high intensity defoliation the prior growing season stimulated short-term C allocation to roots in these semi-arid grasslands. Although this response was independent of soil texture, more C was translocated belowground overall in the loamy ecosite. The effect of defoliation intensity and ecosite in regulating short-term C allocation in the plant-soil system in temperate grasslands should be incorporated into future models describing C cycling in grasslands when predicting C dynamics under different management strategies employing contrasting grazing intensities.
... However, gains in soil organic carbon (SOC) content are likely lower after removal of dense invasions ). An increase in cattle numbers would provide financial benefits in the form of increased capital and income from sales, and increases in SOC could translate into financial value in the form of carbon credits in payment-for-ecosystem-services schemes (Follett & Reed, 2010). ...
Climate change, land degradation and invasive alien species (IAS) threaten grassland ecosystems worldwide. IAS clearing and grassland restoration would help to reduce the negative effects of IAS, restore the original vegetation cover and sustain livelihoods while contributing to climate change mitigation, but uncertain financial benefits to local stakeholders hamper such efforts. This study assessed where and when net financial benefit could be realized from Prosopis juliflora management and subsequent grassland restoration by combining ecological, social and financial information.
Impacts of Prosopis invasion and grassland degradation on soil organic carbon (SOC) in nine sublocations in Baringo County, Kenya, were evaluated. Then the financial impacts of Prosopis removal and grassland restoration in the area were calculated and spatially explicit management scenarios for each sublocation modelled, combining geographical information derived from satellite images taken in different years of the invasion with SOC data and socio‐economic data collected in the sublocations.
The expanding Prosopis distribution and density since 1995 have increased cumulated SOC storage on former bare land or degraded grasslands. On former pristine or restored grasslands, however, Prosopis invasion has reduced total SOC storage.
Prosopis removal and grassland restoration are predicted to yield financial benefits through charcoal made from removed trees, increased cattle numbers and carbon credits. However, a trade‐off between increased SOC and net financial benefit was found. The predicted net SOC increase would contribute around one‐tenth, at most, to the net financial benefit.
The available budget, based on Baringo households’ average willingness to pay, would enable removal, on average, of one‐fifth of Prosopis per sublocation in a single year. A larger area can be cleared if Prosopis is sparse than if it is dense. The analyses show that in some sublocations, households’ annual investments could result in restoration of all former grassland areas.
Synthesis and applications . This study shows how integrating and linking detailed ecological, social and financial geodata to develop accurate and realistic invasive alien species management scenarios can illustrate costs and benefits of management interventions in a spatial context. Such scenarios should be used more extensively to support land management decisions.
... It has the potential to store about 1/4 th of world soil carbon (Pineiro et al., 2010). Even though climate, soil, and management practices are governing the carbon sequestration rate in grazing land, it can sequestrates about 20% of the carbon dioxide that could be released annually into the earth's atmosphere from global deforestation (Pineiro et al., 2010;Follett and Reed, 2010). Here, grazing land has the capacity to store carbon in the soil under appropriate grazing pressure; however, it loses carbon under heavy grazing rate. ...
Abstract
Exclosures have gotten recognition as a successful management practice in rehabilitating degraded landscapes. Several exclosures were established in the study area 10 years ago for the restorations of the degraded lands. However, the evaluations of their success and baseline data are still limited. This study was conducted to estimate the biomass and soil organic carbon stocks under two land-use types: exclosure and open grazing land in Karo Simela and Werabu Beriyo Kebels of Woliso Woreda, Southwest Shoa, Ethiopia. Two replicates of exclosures with adjacent open grazing lands were selected purposefully. A systematic sampling method with nested plot design was used for biomass and soil data collection. A total of 24 quadrates each 40mx50m size in the exclosure and 50mx100m in the open grazing land were established. Woody species were inventoried by the non-destructive method. Soil and grass/litter samples were collected from the subplots of the nested plots. A total of 72 composite soil samples (2 land use x 2 kebeles as replication of sites x 2 transect lines x 3 replicates of sample plots x 3 soil depth: 0-30, 30-60 and 60 - 100cm) were collected. The results showed that, biomass and SOC stocks varied significantly (P<0.05) with land uses. The exclosure had higher biomass carbon stock (17.72 ± 7.28 t c ha-1) than the open grazing land (2.28 ± 1.26 t c ha-1). The litter and grass biomass carbon stocks were also higher (1.32 ± 0.67 t c ha-1) in exclosure than in the open grazing land (0.24 ± 0.13 t c ha-1). In terms of SOC stock with soil depths, the variation was not significant except at the upper stratum (0-30cm); whereas, the overall mean of SOC stock was higher in the exclosure (119.47 ± 19.39 t c ha-1) than in the open grazing land (98.91 ± 19.96 t c ha-1). The significant variation of biomass, litter and soil organic carbon stocks with the land use types were due to the establishment of the exclosure that had enhanced the vegetation and land cover. It had contributed to the biomass and soil organic carbon accumulation. Moreover, the lower values in open grazing land use type were due to the continuous degradation and disturbance in the open grazing land. The result of this study showed that excluding human disturbance and livestock grazing from the degraded ecosystem could enhance the biomass and soil organic carbon stocks of the ecosystem by enabling vegetation recovery.
Keywords/Phrases: Adjacent, carbon stock, degraded ecosystem, exclosure, land use, open grazing land, soil depth
... Rangelands cover approximately one-third of the Earth's land area and at least one billion people depend on these lands to live, both directly through livestock production and indirectly from other resources and ecosystem services [1,2]. They are traditionally characterized by highly heterogeneous natural vegetation communities, which often have a high conservation value, frequently grow in harsh environments [3], are associated with wildlife and/or domestic grazing, and are managed by ecological/traditional rather than agronomic methods [4]. ...
In this study, we analyzed the effects of grazing on native and endemic plant diversity, as well as its relationship with pastoral value along a gradient of abiotic and biotic factors and types of land management in a mountainous area of central-eastern Sardinia, Italy. Plant diversity was estimated by conducting a floristic survey within plots. In total, 231 plant species were recorded in 63 plots distributed within the study area, and this total number included 20 endemic species. Species richness was mainly affected by the type of management, soil attributes, altitude, and bioclimate. Pastoral value was strongly affected by nutrient availability and bioclimate. Our results suggest that the cover of endemic species increases with altitude. Finally, in Sardinian rangelands, a negative effect of grazing pressure on endemic species was observed.
Soil organic carbon (SOC) in grasslands not only plays an important role in carbon cycle but also largely affects soil function and thus determines grasslands' productivity. However, the influence mechanism of different factors on SOC storage in grasslands of northern China remains unclear. Based on an extensive field investigation and multiple statistical approaches, we mapped SOC of the grassland in northern China, and explored their correlations with climatic factors, biological factors, human activity intensity (HAI), and soil physicochemical factors. The effects of these factors on SOC were also analyzed by structural equation model. The results showed that the SOC varied across the regions and was strongly correlated with soil chemical factors (i.e., soil total nitrogen [TN], amorphous Al, and amorphous Fe) and soil physical factors (i.e., clay, silt, and sand). HAI, which was mainly influenced by grazing, had a significant but negative impact on SOC. Different from previous studies, we found that climatic factors such as temperature and precipitation indirectly affected SOC by influencing biological factors such as vegetation coverage, vegetation height, Shannon–Weiner index, and species richness. The soil physicochemical properties and HAI were the dominant influencing factors for controlling SOC distribution in the grasslands of northern China. Our findings will further increase the understanding of the carbon cycle in grassland ecosystems, while providing important scientific references for temperate grassland ecosystem management.
Livestock grazing, as a primary utilization practice for grasslands, plays a crucial role in carbon cycling process and its budget. Whether the impacts of different grazing intensities on carbon sequestration vary with precipitation over a broad geographic scales across China's grasslands remains unclear. In the context of striving for carbon neutrality, we carried out a meta-analysis based on 156 peer-reviewed journal articles to synthesize the general impacts of different grazing intensities on carbon sequestration with different precipitations. Our results showed that light, moderate, and heavy grazing dramatically reduced the soil organic carbon stocks by 3.43 %, 13.68 %, and 16.77 % in arid grasslands, respectively (P < 0.05), while light and moderate grazing did not alter soil organic carbon stocks in humid grasslands (P > 0.05). Moreover, the change rates of soil organic carbon stocks were all tightly positively associated with those of soil water content under different grazing intensities (P < 0.05). Further analysis revealed strong positive relationships between mean annual precipitation with the change rates of above- and belowground biomasses, soil microbial biomass carbon, and soil organic carbon stocks under moderate grazing intensity (P < 0.05). These findings imply that carbon sequestration is relatively less tolerant to grazing disturbance in arid grasslands than humid grasslands, which may be primary due to the grazing-intensified water limitation for plant growth and soil microbial activities under low precipitation. Our study is of implication to predict carbon budget of China's grasslands and help adopt sustainable management to strive for carbon neutrality.
Ongoing climate change and long-term overgrazing are the main causes of grassland degradation worldwide. Phosphorus (P) is typically a limiting nutrient in degraded grassland soils, and its dynamics may play a crucial role in the responses of carbon (C) feedback to grazing. Yet how multiple P processes respond to a multi-level of grazing and its impact on soil organic carbon (SOC), which is critical for sustainable grassland development in the face of climate change, remains inadequately understood. Here, we investigated P dynamics at the ecosystem level in a 7-year-long multi-level grazing field experiment and analyzed their relation to SOC stock. The results showed that, due to the greater P demand for compensatory plant growth, grazing by sheep increased the aboveground plants' P supply (by 70 % at most) while decreasing their relative P limitation. The increase in P in aboveground tissue was associated with changes in plant root-shoot P allocation and P resorption, and the mobilization of moderately labile organic P in soil. Affected by the altered P supply under grazing, corresponding changes to root C stock and soil total P were two major factors impacting SOC. Compensatory growth-induced P demand and P supply processes responded differently to grazing intensity, resulting in differential effects on SOC. Unlike the light and heavy grazing levels, which reduced the SOC stock, moderate grazing was capable of maintaining maximal vegetation biomass, total plant biomass P, and SOC stock, mainly by promoting biologically- and geochemically-driven plant-soil P turnover. Our findings have important implications for addressing future soil C losses and mitigating higher atmospheric CO2 threats, as well as maintaining high productivity in temperate grasslands.
Agriculture alone produces 10% of UK greenhouse gas emissions, despite constituting less than 1% of gross domestic product (GDP). Climate mitigation targets set by the United Nations Paris Climate Agreement look to land management strategies to limit global warming below 2°C. At present, it is estimated that a minimum of 40% of earth's farmed land is poorer in quality than it was in the 1970s. Simultaneously three quarters of the earth's species are being lost within a short geological time frame described as the sixth, mass extinction event. Unlike the past five mass extinction events, the cause this time is exclusively the result of human activities, of which land use change associated with agriculture is one. Increasingly the argument for changing how we farm is gathering momentum. This article aims to provide a review of regenerative agriculture practices, and a reasoning as to why it should play a part in a sustainable farming future. The green revolution enabled the planet to keep feeding an expanding global population with production of cereal crops often tripling with only a 30% increase in land use; what is now needed is an ability to maintain production while providing part of the solution to the twin global threats of climate change and biodiversity loss.
Moderate grazing has been widely proven to improve ecosystem functioning and have profound effects on the carbon cycling and storage in grassland ecosystems, which highly depend on grazing duration and grassland type. However, the effects of moderate grazing durations on carbon sequestration with different grassland types over broad geographic scales across China remain underexplored in the context of striving for carbon neutrality. Here, we explored the probably different responses of carbon sequestration to moderate grazing duration for temperate and alpine grasslands based on 129 published literatures regarding the China's grasslands. The results showed the soil organic carbon stocks were significantly increased during short-term (<5 years) grazing duration, while significantly decreased during medium- (5–10 years) and long-term (≥ 10 years) grazing durations in temperate grasslands. However, the soil organic carbon stocks were significantly decreased during short-term grazing duration, while showed no significant changes during medium- and long-term grazing durations in alpine grasslands. The changes in soil organic stock were significantly positively correlated with the changes in belowground biomass, root:shoot, and microbial biomass carbon (P < 0.05). These findings suggest that the temperate grasslands change from carbon sink to carbon source with moderate grazing duration increasing, while the alpine grasslands present an opposite change pattern from carbon source to carbon sink, regulated by grazing-altered carbon input and microbial activities. Our study might have significant implications for future sustainable management practices for carbon sequestration of China's grasslands.
Background
The degradation of alpine meadows has induced substantial losses of soil organic carbon (SOC) on the Tibetan Plateau. A commonly-used method for rehabilitating degraded alpine meadows in this region is establishing cultivated grasslands through sowing seed mixtures, but its impact on the biochemical stability of SOC has remained inadequately explored.
Methods
In this study, a total of 20 composited 0-20 cm soil samples were collected from a heavily degraded alpine meadow (DM) and three adjacent cultivated grasslands established for 3 years (CG3), 12 years (CG12), and 17 years (CG17) on the eastern Tibetan Plateau, and the SOC pool was separated into labile C pool I (LOC I), labile C pool II (LOC II), and recalcitrant C pool (ROC) in order to investigate changes in contents of SOC fractions that have different biochemical stabilities after the establishment of cultivated grassland.
Results
Although the establishment of cultivated grasslands led to increases in soil total organic C content, the increase was only significant in samples with 17 years of cultivation. We found that the contents of the three SOC fractions were higher at CG3 and CG12 compared with those in the DM, and the differences were only significant for soil LOC II. By comparison, 17 years of cultivation led to significant increases in all of the SOC fraction contents. The results implied that different cultivation years had distinct impacts on SOC fractions in cultivated grasslands, and longer cultivation years contributed to accumulated soil ROC. The recalcitrance index of SOC in the DM was higher than that at CG3 and CG12, but lower than that at CG17. This was possibly due to the generally low litter quality of cultivated grasslands, which led to a slow release of complex compounds to soils. Moreover, it was observed that soil C:N ratio was a potential indicator of SOC biochemical stability because of their close correlation.
Conclusions
Our findings suggest that the long-term establishment of cultivated grasslands on DM is a promising solution to recovering both the quantity and stability of SOC on the Tibetan Plateau.
Grassland degradation is commonly thought to cause soil organic carbon (SOC) change, and the response of SOC stock to degradation is highly dependent on grassland type. However, the effects of grassland type on changes in SOC stocks with grassland degradation over broad geographic scales remain unclear. Here, we explored the probably different responses of SOC stocks to grassland degradation for alpine meadows and alpine steppes based on 58 peer‐reviewed publications regarding the Qinghai‐Tibetan Plateau. The results showed that SOC stock consistently decreased with increasing degradation levels in both alpine meadows and steppes, whereas the magnitudes of reduction of SOC stock in alpine meadows were significantly larger than those in alpine steppes (P < 0.05). The variations in SOC stock were significantly positively correlated with variations in aboveground biomass in the alpine steppes only (P < 0.05) but were significantly positively correlated with variations in belowground biomass in both alpine meadows and alpine steppes (P < 0.01). The relationships between change rates of SOC stock with initial SOC stock and mean annual precipitation were both significantly negative during the lightly and moderately degraded stages, while the negative relationship became nonsignificant for the heavily degraded stage (P > 0.05). These findings suggest that soil organic carbon stock responded more sensitively to degradation in alpine meadows with higher initial SOC stock and annual mean precipitation than in alpine steppes. Our study might have significant implications for future sustainable management practices for carbon sequestration of alpine grasslands on the Qinghai‐Tibetan Plateau. This article is protected by copyright. All rights reserved.
Greenhouse gas removal (GGR) technologies can remove greenhouse gases such as carbon dioxide from the atmosphere. Most of the current GGR technologies focus on carbon dioxide removal, these include afforestation and reforestation, bioenergy with carbon capture and storage, direct air capture, enhanced weathering, soil carbon sequestration and biochar, ocean fertilisation and coastal blue carbon. GGR technologies will be essential in limiting global warning to temperatures below 1.5°C (targets by the IPCC and COP21) and will be required to achieve deep reductions in atmospheric CO2 concentration. In the context of recent legally binding legislation requiring the transition to a net zero emissions economy by 2050, GGR technologies are broadly recognised as being indispensable.
This book provides the most up-to-date information on GGR technologies that provide removal of atmosphere CO2, giving insight into their role and value in achieving climate change mitigation targets. Chapters discuss the issues associated with commercial development and deployment of GGRs, providing potential approaches to overcome these hurdles through a combination of political, economic and R&D strategies.
With contributions from leaders in the field, this title is an indispensable resource for graduate students and researchers in academia and industry, working in chemical engineering, mechanical engineering and energy policy.
Facilitative role of woody plants often modifies understory soil parameters. However, the effect of individual shrubs on soil qualitative parameters could be variable in the grasslands depending on the presence of grazing, and little is known about how facilitative interactions between woody plants and soil change with grazing. Therefore, in this study, we compared the conservative role of woody plant species on soil between grazed and ungrazed areas. Soil samples were collected beneath (patch) and outside (interpatch) of the canopy of Crataegus pseudomelanicarpa in grazed and ungrazed areas in the autumn. The content of total nitrogen (TN), total carbon (TC), particulate organic matter (POM), moisture and soil aggregate stability were compared between patch and interpatch in both grazed and ungrazed areas. Generally, the results showed that the main effects of the woody species were significant on the soil parameters (p < 0.05). The presence of the woody species in both grazed and ungrazed areas improved the values of all understory soil qualitative parameters. However, soil parameters such as POM, TC and TN were significantly higher in the patch (24.43 gr/kg, 1.53% and 0.20%, respectively) than in interpatch (15.41 gr/kg, 1.35 and 0.14%, respectively) in the grazed area, while in the ungrazed area, these differences were less pronounced or not significant between patch (26.00 gr/kg, 1.43 and 0.18%, respectively) and interpatch (19.10 gr/kg, 1.43 and 0.15%, respectively). We conclude that the nursing role of woody plants on soil in the degraded grasslands is more important when associated with grazing and should be considered in the restoration projects.
Rangelands occupy more than half of the terrestrial ecosystems and their management has a significant impact on the global carbon cycle. They are often managed for pasture and forage for livestock. This study examined impact of grazing management practices on biomass and carbon stock in dry lowland rangelands. A systematic transect sampling was applied to measure vegetation data, and to collect soil and herbaceous samples from the field. Allometric and species-specific equations were used to determine the woody biomass. Herbaceous biomass and soil carbon were analyzed in a laboratory. The results showed that herbaceous vegetation accounted for 5–15% of the total carbon stock while the woody vegetation accounted only for 0.3–1% of the total carbon stock. The soil is the largest carbon pool holding more than 90 % of the total carbon. Enclosures and bush clearing favored more herbaceous growth and changed the vegetation dynamics. As a result, the grasslands sequestered significantly high (P < 0.05) amount of soil carbon compared to the bush lands and the tree savannah. The management practices improved total carbon sequestration by 12.2%—26% in the system. There is high seasonal dynamics in the herbaceous carbon with a significant increase (P < 0.5) during the wet season. Soil carbon showed an inverse relationship with stem density, soil bulk density and slope. Rainfall and altitude have a positive influence on soil carbon. Total carbon stock in the managed rangelands was 19.8% higher than in the unmanaged rangelands. It can be concluded that enclosures and bush clearing enhance soil carbon sequestration. At the estimated annual sequestration rate of 1.6–3.5 t CO2e ha⁻¹ yr⁻¹ into the soil and 2.2–5.6 t CO2e ha⁻¹ yr⁻¹ into the total carbon stock in the system, the rangelands can make significant contribution to climate change mitigation.
Agriculture is a major contributor of green house gas emissions and livestock component have significant contribution, sheep being an important part of animal husbandry also contributes to carbon footprints (CFs) of environment through enteric fermentation, manure emissions and inputs used in sheep husbandry. Toaugment productivity and lower environmental impact of livestock, intensive farming is a promising strategy; yet, the approach of feeding more amount of concentrate to increase the productivity of animals was less competent and severed environmental effects compared to increasing fodder production. Furthermore, to avoid dependence ongrazing pasturesand provide year round quality fodder to the animals, carbon foot print from forage production required for stall feeding should be taken in to consideration along with other practices for conducting life cycle assessment of sheep farming. In this study, sheep rearing of popular breeds (Malpura, Avishaan, Patanwadi and Kheri) altogether with dominant forage production systems (napier, perennial grasses, forage legumes and bajra) was assessed in terms of carbon foot prints and output of crops as well as sheep. Among all the crops, perennial grasses required less input and very low CFs of inputs followed by forage legumes. The mean carbon foot print of finished lambs was 8.9, 9.5, 9.3 and 5.7 kg CO2e/kg live weight in Malpura, Avishaan, Patanwadi and Kheri, respectively. For production of 1 kg fodder on dry matter basis, Napier required around 224.6% higher carbon input than perennial grasses along with maximum productivity (carbon output) of 67.4% as compared to other crops. Grasses being marginal crops required very low carbon input approximately 794.5% lower as compared to Napier production. For meat, Avishaan proved its superiority in terms of higher meat production which resulted in higher CFs from meat in Avishaan which was around 89.9 and 85.5% higher than Malpura and Patanwadi, respectively. In case of milk, Patanwadi was the highest contributor having 20.1 and 14.3% higher CO2-e as compared to Malpura and Avishaan, respectively. The CFs for wool production was also more for Patanwadi by about 15.0 and 22.9% higher than Malpura and Avishaan, respectively. When the CFs of fodder production and sheep farming was studied together, it was revealed that Napier production with Patanwadi rearing contributed maximum CFs over other systems. Grasses cultivated with Avishaan resulted in least CFs contribution. The results suggest that growth of meat/animal production should be done in consideration with the mean carbon footprints of all correlated variables impacting the environment.
Compost is a class of soil amending products that improves the physical, chemical, and biological properties of soils, resulting in better plant health and environmental quality. This chapter describes the practices and benefits of compost in a wide array of uses in agricultural, horticultural, viticulture, forestry, urban landscape, and greenhouses and for erosion, stormwater control, and carbon sequestration. Compost application practices are discussed in general and specific to particular crops. Compost's effects depend on many variables, including the soil type and properties, the characteristics of the compost (e.g., nutrients, maturity, salinity, etc.), application methods, rate, and frequency, and the expected benefits.
The aim of this study was to investigate the effect of afforestation with broadleaf and coniferous species in comparison with natural forests on soil carbon sequestration in Darabkola and Kolt forests. For the study, first three afforestation stands with Acer velutinum Bioss., Alnus subcordata C. A. M. and Cupressus sempervirensvar.horizontalis and one natural forest stand were selected as control stands in both Darabkola and Kolt areas. Five plots were harvested in each plot and in each plot from the four corners and the center of the profile plot to a depth of 0-15 cm, then a composite sample was isolated from these soils for the laboratory (40 samples in total). The experiment was conducted in a completely randomized design with a factorial experiment. According to the results, the two habitats of Darabkola (83.493 tons/hectare) and Kolt (62.028 tons/hectare) in terms of carbon sequestration were not significantly different at the level of five percent (P <0.005), but its amount in Darabkola forest has been more than Colt forest. Also, there was no significant difference between the four populations in terms of carbon sequestration, but this characteristic in Alnus subcordata C. A. M. species (83.862 tons/hectare) and Acer velutinum Bioss (71.682 tons/hectare) had the highest value compared to Cupressus sempervirensvar.horizontalis massif (69.453 Tons/hectare) and natural forest (66.046 tons/hectare). In fact Alnus subcordata C. A. M. species has the highest carbon sequestration compared to the other three populations.
Grazing is the dominant land use across the world, and large mammalian herbivores exert strong influence over biogeochemical cycles. Grazing ecosystems feature C-rich soils, even though herbivores consume a major fraction of plant production to reduce detrital input to soil. Yet, counter-intuitively, moderate grazing can promote net soil-C storage in many ecosystems compared to grazer-exclusion. We address this enigmatic influence of grazers on soil-C and test their indirect effect on proximate drivers of decomposition: microbial extracellular enzyme activity. We used a replicated long-term grazer-exclusion experiment to measure responses in above- and belowground plant biomass, soil-C stock, microbial biomass, labile/recalcitrant C pools and three enzymes relevant to the C-cycle: peroxidase—which initiates decomposition of recalcitrant matter, alongside beta-glucosidase and cellobiohydrolase—which act further downstream on more labile fractions. Consistent with other ecosystems, upto 12 years of herbivore exclusion did not increase soil-C in the fenced plots despite higher plant biomass and higher potential detrital C-inputs. Grazer-exclusion did not alter microbial biomass; peroxidase increased threefold and beta-glucosidase was doubled; cellobiohydrolase was unaffected. Grazer-exclusion also led to twofold increase in recalcitrant-C and in microbial respiration, but it did not influence labile-C. Structural equation models supported the hypothesis that grazing favours soil-C via its indirect effect on peroxidase, but they did not support that the effects can run in the opposite direction where soil-C affects enzymes. Grazer-mediated shifts in how microbes deploy enzymes emerge as a plausible mechanism that affects soil-C. These linkages may be important to maintain soil-C sequestration in drylands which support large mammalian herbivores.
Grasslands can significantly contribute to climate mitigation. However, recent trends indicate that human activities have switched their net cooling effect to a warming effect due to management intensification and land conversion. This indicates an urgent need for strategies directed to mitigate climate warming while enhancing productivity and efficiency in the use of land and natural (nutrients, water) resources. Here, we examine the potential of four innovative strategies to slow climate change including: 1) Adaptive multi-paddock grazing that consists of mimicking how ancestral herds roamed the Earth; 2) Agrivoltaics that consists of simultaneously producing food and energy from solar panels on the same land area; 3) Agroforestry with a reverse phenology tree species, Faidherbia (Acacia) albida, that has the unique trait of being photosynthetically active when intercropped herbaceous plants are dormant; and, 4) Enhanced Weathering, a negative emission technology that removes atmospheric CO2 from the atmosphere. Further, we speculate about potential unknown consequences of these different management strategies and identify gaps in knowledge. We find that all these strategies could promote at least some of the following benefits of grasslands: CO2 sequestration, non-CO2 GHG mitigation, productivity, resilience to climate change, and an efficient use of natural resources. However, there are obstacles to be overcome. Mechanistic assessment of the ecological, environmental, and socio-economic consequences of adopting these strategies at large scale are urgently needed to fully assess the potential of grasslands to provide food, energy and environmental security.
Horses and burros, including especially wild, naturally living ones, play a major role in combatting Global Warming and do this in a variety of ways. One of these concerns their superior ability to sequester, or "lock away," Carbon. They remove Carbon from the atmosphere, where, in the form of carbon dioxide, methane and other heat-trapping gases, this element accelerates a dangerous, oven-like increase in temperatures on our entire planet Earth. All members of the horse family Equidae, as well as their Mammalian Order Perissodactyla, play this same vital and life-saving role. This includes also the various onagers, zebras, tapirs and rhinoceroses of the world, nearly all of which are listed as threatened or endangered with extinction in the Red List put out by the World Conservation Union's (IUCN) Species Survival Commission (2021). As a member of the IUCN SSC, I have written action plans and species resumes to mount a global effort to save and restore these very important species together with their appropriate habitats. (See https://iucn.org/commissions/ssc-groups/mammals/specialist-groups-a-e/equid also tapir.) Much of the superior ability of the horses and burros to sequester Carbon is related to their special digestive system. This is different from the ruminant digestive system of many other plant eaters, or herbivores, in our world. These include many millions of cattle, sheep, goats, deer, elk, etc., that are overly forced in excessive numbers onto life communities, or ecosystems, the world over, including in the United States. Horses and burros possess a monogastric, cecal-fermenting digestive system that is less complex than that of the multi-stomach, rumen-fermenting digestive system of ruminant herbivores. As a consequence , these equids do not as thoroughly decompose their food as do ruminants. As a consequence, the chemistry of equid droppings is more organically intact and complex. This fact has enormously positive consequences for habitats. One of the chief advantages is that equine feces contribute to more vital soils by augmenting their humus content. As many gardeners know, humus is crucial to healthy soils, making these more nutrient-rich and water-retaining. Indeed, the renowned San Francisco Botanical Garden has soils that were enriched from sandy beach loam by mixing horse manure clear back in the 1870s and horse droppings continue to play a major part in keeping this garden so exuberant today. The health of ecosystems depends upon healthy plant life, which depends upon healthy soils. Horses create more robust soils that cause grasses, forbs, bushes and trees to flourish when adequate water, healthy air and sunshine is added into the mixture. In regions where they belong, horses have been proven to allow a much greater diversity of species of both plants and animals together with their interrelated roles in the life community. This gives greater resistance and resilience to horse-containing ecosystems. This has been proven here in North America and in many places all over the world. One prime example concerns the restoration of Spanish Retuerta horses in overgrazed ecosystems in Andalusia. This ongoing program is restoring ecosystems that had been overgrazed by livestock for
Most prior studies have found that substituting biofuels for gasoline will reduce greenhouse gases because biofuels sequester
carbon through the growth of the feedstock. These analyses have failed to count the carbon emissions that occur as farmers
worldwide respond to higher prices and convert forest and grassland to new cropland to replace the grain (or cropland) diverted
to biofuels. By using a worldwide agricultural model to estimate emissions from land-use change, we found that corn-based
ethanol, instead of producing a 20% savings, nearly doubles greenhouse emissions over 30 years and increases greenhouse gases
for 167 years. Biofuels from switchgrass, if grown on U.S. corn lands, increase emissions by 50%. This result raises concerns
about large biofuel mandates and highlights the value of using waste products.
Pastureland, which includes improved, native, and naturalized pastures, accounts for 51 Mha of the 212 Mha of privately held grazing land in the U.S. (Sobecki et al., Ch. 2). This chapter focuses on improved pasture in humid regions (>625 mm mean annual precipitation).
Ecosystem properties of surficial (0-10 cm) soils in remnant herbaceous patches were compared to those of contrasting woody plant patch types (upland discrete cluster, upland grove, and lowland woodland) where shifting land cover is known to have occurred over the past 50-77 yr. The purpose of this study was to evaluate and quantify the biogeochemical consequences and subsequent developmental rates of woody plant formation on sites formerly dominated by grasses. Clay and water content of woodland soil patches was higher than that of soils associated with upland discrete cluster and grove patches. Even so, lowland woody patches were generally comparable to upland grove and discrete shrub cluster patches with respect to soil organic carbon (SOC), soil N, the ratio of annual N mineralization:total N, annual litterfall, and root biomass. The fact that finer soil texture, enhanced soil moisture, and the more advanced age of lowland woody patches did not translate into greater accumulations of SOC and N relative to upland grove and discrete cluster patches suggests that C and N losses might be higher in recently developed lowland woodland communities. Fluctuations in monthly root biomass standing crop (0-10 cm) far exceeded annual foliar litterfall in upland and lowland woody patch types, suggesting that belowground inputs of organic matter may drive changes in soil physical and chemical properties that occur subsequent to woody plant establishment. The estimated annual mean rates of soil C accretion in the "islands of fertility" that developed subsequent to tree/shrub encroachment were variable and ranged from 8 to 23 g/m2 (in groves and discrete clusters, respectively); N accretion ranged from 0.9 to 2.0 g/ m2 (in groves and discrete clusters, respectively), even though mean annual N mineralization rates were three- to fivefold greater than those measured in remnant herbaceous patches. Woody plant proliferation in grasslands and savannas in recent history has been widely reported around the world. The causes for this shift in vegetation are controversial and center around changes in livestock grazing, fire, climate, and atmospheric CO2. Our data, which are conservative in that they examine only the upper 10 cm of the soil profile, indicate that the rate and extent of soil C and N accumulation associated with this phenomenon can be rapid, substantial, and accompanied by increased N turnover. This geographically extensive vegetation change thus has important implications for understanding how the global carbon and nitrogen cycles may have been altered since Anglo-European settlement of arid and semiarid regions.
The potential to sequester carbon and increase organic nutrient storage in disturbed soils, such as those reclaimed after surface coal mining, appears to be significant. Quantification of organic carbon accumulation is complicated, however, by the presence of coal and coal dust in these soils. Our preliminary data on organic matter content of reclaimed soils at surface coal mines in Wyoming suggest they are sequestering carbon at a rapid rate. Data from a surface mine reclamation site near Hanna, WY indicate that surface (0-15 cm) soil organic carbon content has increased from a low of 10.9 g C kg-1 soil in 1983 to 18.6 g C kg-1 soil in 1998 and to 20.5 g C kg-1 soil in 2002. Undisturbed soil directly adjacent to the reclaimed site has a mean organic carbon content of 15.1 g kg-1 soil. At a mine near Glenrock, WY, soil organic carbon at a site reclaimed in 1979 increased from an estimated low of 5.8 g C kg-1 soil to a current level of 18.4 g C kg-1 soil. Organic carbon content of undisturbed soils adjacent to the reclaimed area range from 9.9 to 15.7 g C kg-1 soil. In contrast to the elevated organic carbon content, amounts of microbial biomass in reclaimed soils at both mines are lower than in nearby undisturbed soils (ca. 60% or less). We have collected similar data from a number of other surface coal mines in Wyoming. We hypothesize that decomposition rates are slow in reclaimed mine soils due to low microbial activity relative to that in undisturbed soils. Additional Keywords: carbon sequestration, reclaimed mine soil, soil organic matter, surface coal mine, soil microbial biomass
Recent concern about global warming has led to attempts to estimate the effects of management on carbon sequestration in soil. The objective of this study is to determine the amount of soil organic carbon (SOC) degraded by agricultural practices and the rate of carbon sequestration in soils after restoration of grass for various periods of time. The SOC contents of previously cultivated clay soils (Udic Haplusterts) in central Texas returned to grass 6, 26, and 60 years ago are compared with those of soils in continuous agriculture for more than 100 years and those of prairie soils that have never been tilled. Surface (0 to 5 cm) SOC concentration ranged from 4.44 to 5.95% in the prairie to 1.53 to 1.88% in the agricultural sites. Carbon concentration in restored grasslands was generally intermediate to that reported for the native prairie and agricultural sites. The SOC mass in the surface 120 cm of the agricultural soils was 25 to 43% less than that of native prairie sites. After the establishment of grasses, SOC mass in the grass sites was greater than at the agricultural sites. A linear relationship between the length of time in grass and the amount of SOC sequestered in the surface 60 cm fit well for time periods from 6 to 60 years. The slope of this function provided an estimate of the carbon sequestration rate, in this case 447 kg C ha-1 yr-1. At this rate, it would require nearly an additional century (98 years) for the 60-year grass site to reach a carbon pool equivalent to that of the prairie.
An experiment was conducted to evaluate the influence of long-term (>25 yrs) grazing on soil organic carbon (SOC) and total soil nitrogen (N) accumulation beneath individual plants of three perennial grasses along an environmental gradient in the North American Great Plains. The zone of maximum SOC and N accumulation was restricted vertically to the upper soil depth (0-5 cm) and horizontally within the basal area occupied by individual caespitose grasses, which contributed to fine-scale patterning of soil heterogeneity. Long-term grazing mediated SOC and N accumulation in the tall-, mid-and shortgrass communities, but the responses were community specific. SOC and N were lower beneath Schizachyrium scoparium plants in long-term grazed sites of the tall-and midgrass communities, but higher beneath Bouteloua gracilis plants in the long-term grazed site of the shortgrass community. SOC, but not N, was greater in soils beneath compared to between S. scoparium plants in an abandoned field seeded in 1941, indicating that this caespitose grass accumulated SOC more rapidly than N. SOC and N were greater in the 0-5 cm soil depth beneath a caespitose grass (S. scoparium) compared to a rhizomatous grass (Panicum virgatum) in the tallgrass community, with no significant accumulation of either SOC or N beneath P. virgatum plants. Grazing appears to indirectly mediate nutrient accumulation beneath caespitose grasses along the environmental gradient by modifying the size class distribution of plants. Populations with a greater proportion of large plants have a greater potential for biomass incorporation into soils and may more effectively capture redistributed organic matter from between plant locations. Contrasting plant responses to grazing at various locations along the environmental gradient conform to the predictions of the generalized grazing model, as the selection pressures of grazing and aridity may have also influenced the ability of caespitose grasses to accumulate nutrients in soils beneath them by mediating grazing resistance, competitive ability and population structure.
World soils have been a major source of enrichment of atmospheric concentration of CO2 ever since the dawn of settled agriculture, about 10,000 years ago. Historic emission of soil C is estimated at 78 ± 12 Pg
out of the total terrestrial emission of 136 ± 55 Pg, and post-industrial fossil fuel emission of 270 ± 30 Pg. Most soils
in agricultural ecosystems have lost 50 to 75% of their antecedent soil C pool, with the magnitude of loss ranging from 30
to 60 Mg C/ha. The depletion of soil organic carbon (SOC) pool is exacerbated by soil drainage, plowing, removal of crop residue,
biomass burning, subsistence or low-input agriculture, and soil degradation by erosion and other processes. The magnitude
of soil C depletion is high in coarse-textured soils (e.g., sandy texture, excessive internal drainage, low activity clays
and poor aggregation), prone to soil erosion and other degradative processes. Thus, most agricultural soils contain soil C
pool below their ecological potential. Adoption of recommend management practices (e.g., no-till farming with crop residue
mulch, incorporation of forages in the rotation cycle, maintaining a positive nutrient balance, use of manure and other biosolids),
conversion of agriculturally marginal soils to a perennial land use, and restoration of degraded soils and wetlands can enhance
the SOC pool. Cultivation of peatlands and harvesting of peatland moss must be strongly discouraged, and restoration of degraded
soils and ecosystems encouraged especially in developing countries. The rate of SOC sequestration is 300 to 500 Kg C/ha/yr
under intensive agricultural practices, and 0.8 to 1.0 Mg/ha/yr through restoration of wetlands. In soils with severe depletion
of SOC pool, the rate of SOC sequestration with adoption of restorative measures which add a considerable amount of biomass
to the soil, and irrigated farming may be 1.0 to 1.5 Mg/ha/yr. Principal mechanisms of soil C sequestration include aggregation,
high humification rate of biosolids applied to soil, deep transfer into the sub-soil horizons, formation of secondary carbonates
and leaching of bicarbonates into the ground water. The rate of formation of secondary carbonates may be 10 to 15 Kg/ha/yr,
and the rate of leaching of bicarbonates with good quality irrigation water may be 0.25 to 1.0 Mg C/ha/yr. The global potential
of soil C sequestration is 0.6 to 1.2 Pg C/yr which can off-set about 15% of the fossil fuel emissions.
Management practices can significantly influence carbon sequestration by rangeland ecosystems. Grazing, burning, and fertilization have been shown to increase soil carbon storage in rangeland soils of the Great Plains. Research was initiated in 2001 in northwestern South Dakota to evaluate the role of interseeding a legume, Medicago sativa ssp. falcata, in northern mixed-grass rangelands on carbon sequestration. Sampling was undertaken on a chronosequence of sites interseeded in 1998, 1987, and 1965 as well as immediately adjacent untreated native rangeland sites. Soil organic carbon exhibited an increase of 4% in the 1998, 8% in the 1987, and 17% in the 1965 interseeding dates compared to their respective native untreated rangeland sites. Nitrogen fixation by the legume led to significant increases in total soil nitrogen and increased forage production in the interseeded treatments. Increases in organic carbon mass in this rangeland ecosystem can be attributed to the increase in soil organic carbon storage and the increased aboveground biomass resulting from the increased nitrogen in the ecosystem. The practice of interseeding adaptable cultivars of alfalfa into native rangelands may help in the mitigation of elevated atmospheric carbon dioxide and enhance the long-term sustainability of the ecosystem.
Very little is known about the effect of overgrazing on carbon loss from soil in semi-arid savannas and woodlands of South America. Soil carbon parameters were measured in a 10,000 ha restoration project in the western Chaco of Argentina (24°43′S and 63°17′W). Three situations were compared: highly restored (HRS), moderately restored (MRS) and highly degraded (HDS). Soil and litter samples were recovered in the dry and wet seasons. SOC and CO2–C values decreased from the HRS (7.0 kg m−2 and 130 g m−2) to the HDS (1.5 kg m−2 and 46 g m−2) whereas the C mineralization rate increased toward the less restored sites (0.96–2.29). Surface-litter C was similar in both sites under restoration (260 and 229 g m−2), being non-existent at the HDS. Leaves from woody species dominated surface-litter in the HRS, whereas grass material was predominant in the MRS. During the wet season, the SOC decreased, whereas both CO2–C and C mineralization rate increased. The magnitude of the between-season differences was highest at the HDS (62% in SOC, 55% in CO2, and 80% in C mineralization rate). We estimated that C loss since introduction of cattle into the forest was 58 Mg ha−1, reaching a total of 2×1015 g at for the entire Chaco. These values are higher than those caused by the conversion of savannas and other ecosystems into agriculture or cultivated pastures. The amount of C fixed in the highly restored site (275 g ha−1 per year) indicates that the Chaco soils have a significant potential as atmospheric carbon sinks.
The application of bio-char (charcoal or biomass-derived black carbon (C)) to soil is proposed as a novel approach to establish a significant, long-term, sink for atmospheric carbon dioxide in terrestrial ecosystems. Apart from positive effects in both reducing emissions and increasing the sequestration of greenhouse gases, the production of bio-char and its application to soil will deliver immediate benefits through improved soil fertility and increased crop production. Conversion of biomass C to bio-char C leads to sequestration of about 50% of the initial C compared to the low amounts retained after burning (3%) and biological decomposition (∘C common for pyrolysis). Existing slash-and-burn systems cause significant degradation of soil and release of greenhouse gases and opportunies may exist to enhance this system by conversion to slash-and-char systems. Our global analysis revealed that up to 12% of the total anthropogenic C emissions by land use change (0.21 Pg C) can be off-set annually in soil, if slash-and-burn is replaced by slash-and-char. Agricultural and forestry wastes such as forest residues, mill residues, field crop residues, or urban wastes add a conservatively estimated 0.16 Pg C yr−1. Biofuel production using modern biomass can produce a bio-char by-product through pyrolysis which results in 30.6 kg C sequestration for each GJ of energy produced. Using published projections of the use of renewable fuels in the year 2100, bio-char sequestration could amount to 5.5–9.5 Pg C yr−1 if this demand for energy was met through pyrolysis, which would exceed current emissions from fossil fuels (5.4 Pg C yr−1). Bio-char soil management systems can deliver tradable C emissions reduction, and C sequestered is easily accountable, and verifiable.
A simulation model of the grassland carbon cycle (CCGRASS) was developed to evaluate the long-term effects of different management strategies and various environmental conditions on carbon sequestration in a loam soil under permanent grassland in the Netherlands. The model predicted that the rate of increase in the amount of soil organic carbon will be greatest at low to moderate application rates of nitrogen (100-250 kg N/ha per year). This is because the annual gross photosynthetic uptake of CO2 in permanent grassland is hardly influenced by the level of N supply. Since N shortage stimulates the growth of the unharvested plant parts (roots and stubble) the carbon supply to the soil is highest at low to moderate N application rates. The rate of increase in soil organic carbon will be greater under grazing than under mowing as a result of a greater amount of carbon added to the soil. Increase of atmospheric CO2 concn may induce an increase in decomposition rate of soil organic matter due to simultaneously increased temperatures. At the same time, plant productivity and thus carbon supply to the soil will be stimulated due to the CO2-fertilization effect. Assuming a temperature increase of 3 degrees C if the present atmospheric CO2 concn doubles, the model predicted that the combined effect of elevated CO2 and temperature will slightly reduce the rate of increase in the amount of organic carbon in grassland soils compared to that under unchanged environmental conditions. There was 2% less carbon sequestration by grassland at the end of a 100 year period as a result of these changes in environmental conditions. The separate effects of increased temperature or elevated CO2 were 10% less and 10% more carbon storage after 100 years, resp.
Broadly scaled information about the extent and character of U.S. grazing lands provides a context for considering the more finely scaled processes driving carbon (C) cycling on grazing lands. Such information also is necessary for estimating the potential for grazing lands to sequester atmospheric C at local, regional, national, or global scales, relative to such other general land cover/use categories as cropland and forest. The terms ̋broad̏ and ̋finȅ scale appear often throughout this chapter, and we define them as did Turner and Gardner (1991). Broad scale implies coarse spatial resolution of land attributes and correspondingly large areas of land; fine scale refers to a greater degree of spatial resolution of land attributes and smaller areas of land. The land attributes central to our discussion are existing and potential vegetative land cover and soil organic carbon (SOC) content.
Grazing lands represent the largest and most diverse land resource-taking up over half the earth's land surface. The large area grazing land occupies, its diversity of climates and soils, and the potential to improve its use and productivity all contribute to its importance for sequestering C and mitigating the greenhouse effect and other conditions brought about by climate change. The Potential of U.S. Grazing Lands to Sequester Carbon and Mitigate the Greenhouse Effect gives you an in-depth look at this possibility.
This chapter reviews how managing grazing lands (rangelands and pastures) affects soil´ s physical quality, with particular reference to soil organic C (SOC) content and its effect on soil. Grazing and cultivation also influence the soil chemical properties of rangelands (Dormaar and Willums, 1989), but this chapter focuses only on soil´ s physical quality.
Previous work (Lal et al.,1998) described greenhouse gas processes, global warming concerns, and the potential of U.S. cropland soils to sequester C and mitigate the greenhouse effect. That work was based on thepotential C sequestration that results from land conversion, land restoration, and intensification through theuse of conservation tillage, improved water and fertility management, and improved cropping systems. The estimates were that 75 to 208 (mean = 142) MMTC/yr could be sequestered in cropland soils.
The effects of root-plowing on soil organic carbon and nitrogen were investigated by comparing paired undisturbed native rangeland with root-plowed sites in the southern Great Plains. Time since root-plowing ranged from 4 to 22 years. We hypothesized that following root-plowing (1) soil carbon would initially drop but recover to the level of untreated range within a 5-10 year period, and (2) the permanent removal of mesquite trees, which enhance ecosystem carbon and nitrogen and provide shade that lowers soil temperature, would result in a slow decline in soil carbon and nitrogen in this ecosystem. There were not significant differences due to treatment for either soil carbon mass ( g m-2) (P=0.81) or nitrogen mass (P=0.62). There were significant differences in soil carbon mass (P=0.0014) with respect to elapsed time since plowing. The upper soil layer (0-100mm) had higher carbon levels (P=0.0001) than the deeper soil layer (100-200mm)(1422 ± 210 g m-2 vs. $1111\pm 206\ {\rm g}\ {\rm m}^{-2})$. Differences in soil nitrogen were similar to those of soil carbon. There were significant differences in nitrogen among years-since-root-plowing observations (P=0.003) and the upper soil layer had higher nitrogen levels than the deeper soil layer $(138\pm 18\ {\rm g}\ {\rm m}^{-2}\ {\rm vs}.\ 107\pm 18\ {\rm g}\ {\rm m}^{-2})$(P=0.0001). When the data were analyzed using paired native site values as a covariate to account for site differences, the sites that had been root-plowed 4 years previously had higher soil carbon (P
Understanding the temporal response of infiltration rate and interrill erosion to selected livestock grazing strategies is necessary for the continued soil and water conservation of rangeland. Infiltration rate and interrill erosion were sampled bimonthly from 1978-1984 on pastures grazed continuously (MCG) and moderately stocked (8.1 ha ${\rm AU}^{-1}$ ); continuously (HCG) and heavily stocked (4.6 ha ${\rm AU}^{-1}$ ); high-intensity, low-frequency (HILF) and moderately stocked (8-1; 17:119 day, stocked at 8.1 ha ${\rm AU}^{-1}$ ); short duration (SDG) and heavily stocked (14-1; 4:50 day, stocked at 4.6 ha ${\rm AU}^{-1}$ ). The MCG and HILF pastures were able to recover from droughts and maintain initial infiltration rates and interrill erosion. In contrast, infiltration rates decreased and interrill erosion increased on HCG and heavily stocked SDG pastures. The trend of infiltration rate and interrill erosion deterioration in the heavily stocked SDG and HCG pastures was not gradual; rather, it followed a stair-step pattern typified by decreasing condition during drought and an inability to recover to pre-drought level during periods of above-normal precipitation. The heavy stocking rate and climate rather than grazing strategy were the primary factors influencing the hydrologic responses. Infiltration rates were seasonally cyclic in the SDG and HCG pastures, but no significant seasonal trend could be identified in the MCG pasture. This was attributed to greater midgrass cover and litter accumulation in the MCG pasture which provided cover stability compared to less litter accumulation and a greater dominance of seasonal shortgrasses and forbs in the SDG and HCG pastures. Total organic cover was the most important factor determining infiltration rate. The midgrass bunch growth form and litter accumulation were the most important factors influencing interrill erosion. Both factors increased microrelief, and obstructed sediment transport and interrill erosion.