No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Biodiversity and ecosystem productivity: Implications for carbon storage
Abstract
Recent experiments have found that Net Primary Productivity (NPP) can often be a positive saturating function of plant species and functional diversity. These findings raised the possibility that more diverse ecosystems might store more carbon as a result of increased photosynthetic inputs. However, carbon inputs will not only remain in plant biomass, but will be translocated to the soil via root exudation, fine root turnover, and litter fall. Thus, we must consider not just plant productivity (NPP), but also net productivity of the whole ecosystem (NEP), which itself measures net carbon storage. We currently know little about how plant diversity could influence soil processes that return carbon back to the atmosphere, such as heterotrophic respiration and decomposition of organic matter. Nevertheless, it is clear that any effects on such processes could make NPP a poor predictor of whole-ecosystem productivity, and potentially the ability of the ecosystem to store carbon. We examine the range of mechanisms by which plant diversity could influence net ecosystem productivity, incorporating processes involved with carbon uptake (productivity), loss (autotrophic and heterotrophic respiration), and residence time within the system (decomposition rate). Understanding the relationship between plant diversity and ecosystem carbon dynamics must be made a research priority if we wish to provide information relevant to global carbon policy decisions. This goal is entirely feasible if we utilize some basic methods for measuring the major fluxes of carbon into and out of the ecosystem.
... The plant functional composition and diversity can determine ecosystem productivity, stability, nutrient dynamics, by altering ecosystem function, and composition of soil carbon (C) and nitrogen (N) (Tilman, 1999;Hooper et al., 2000;van Ruijven & Berendse, 2005;Tilma et al., 2006;Fornara & Tilman, 2008). Plant diversity and soil are important contributors to primary productivity and the storages of soil C and N through complex processes (Catovsky et al., 2002;Fornara & Tilman, 2008;Steinbeiss et al., 2008;Schmidt et al., 2011;Musinguzi et al., 2015). With increasing atmospheric carbon dioxide (CO 2 ) concentrations, to sequester atmospheric C in soil is become an important ecosystem function to mitigate the increasing CO 2 (Cong et al., 2014;Turgut, 2015;Garcia-Diaz et al., 2016;Keesstra et al., 2016). ...
... Legumes had previously been identified as a key driver of primary productivity, C sequestration, N accumulation, and mineralization (Lambers et al., 2004;Fornara & Tilman, 2008). The levels of C and N in soil can also affect diversity and plant composition by increasing the amount of C and N (Ferreira et al., 2014;Shang et al., 2014;Parras-Alcántara et al., 2015;Wasak & Drewnik, 2015;Novara et al., 2016) or reducing C and N losses from soil that occurred by respiration, volatilization, and leaching (Catovsky et al., 2002;De Deyn et al., 2008;Phoenix et al., 2008). Many studies have examined how variations in functional groups and plant species richness alter the amount of soil C and N (Oelmann et al., 2007;Fornara & Tilman, 2008;De Deyn et al., 2009). ...
... Third, legumes significantly increased diversity (40%) and plant species richness (100%) in this study. The positive interactions between diversity and productivity have been well documented (Catovsky et al., 2002;Hooper et al., 2005). Compared with aboveground biomass, below-ground biomass ); BGB, Below-ground biomass (BGB, g m À2 ); R, richness index; H, Shannon-Wiener index; E, evenness index. ...
... The plant functional composition and diversity can determine ecosystem productivity, stability, nutrient dynamics, by altering ecosystem function, and composition of soil carbon (C) and nitrogen (N) (Tilman, 1999;Hooper et al., 2000;van Ruijven & Berendse, 2005;Tilma et al., 2006;Fornara & Tilman, 2008). Plant diversity and soil are important contributors to primary productivity and the storages of soil C and N through complex processes (Catovsky et al., 2002;Fornara & Tilman, 2008;Steinbeiss et al., 2008;Schmidt et al., 2011;Musinguzi et al., 2015). With increasing atmospheric carbon dioxide (CO 2 ) concentrations, to sequester atmospheric C in soil is become an important ecosystem function to mitigate the increasing CO 2 (Cong et al., 2014;Turgut, 2015;Garcia-Diaz et al., 2016;Keesstra et al., 2016). ...
... Legumes had previously been identified as a key driver of primary productivity, C sequestration, N accumulation, and mineralization (Lambers et al., 2004;Fornara & Tilman, 2008). The levels of C and N in soil can also affect diversity and plant composition by increasing the amount of C and N (Ferreira et al., 2014;Shang et al., 2014;Parras-Alcántara et al., 2015;Wasak & Drewnik, 2015;Novara et al., 2016) or reducing C and N losses from soil that occurred by respiration, volatilization, and leaching (Catovsky et al., 2002;De Deyn et al., 2008;Phoenix et al., 2008). Many studies have examined how variations in functional groups and plant species richness alter the amount of soil C and N (Oelmann et al., 2007;Fornara & Tilman, 2008;De Deyn et al., 2009). ...
... Third, legumes significantly increased diversity (40%) and plant species richness (100%) in this study. The positive interactions between diversity and productivity have been well documented (Catovsky et al., 2002;Hooper et al., 2005). Compared with aboveground biomass, below-ground biomass ); BGB, Below-ground biomass (BGB, g m À2 ); R, richness index; H, Shannon-Wiener index; E, evenness index. ...
Precipitation infiltration is the most important process for soil water supply of vegetation in the arid regions. Higher infiltration rate is advantageous for vegetation growth and maintenance in the arid areas. Four grassland types (Medicago sativa, Agropyron cristatum, Caragana korshinskii and Stipa capillata ) were selected in this study. Results showed that the infiltration capacity in the legume grasslands was about 30% higher than in the gramineous grasslands and the difference was significant (P? ?0.05). The below-ground biomass, total porosity, capillary porosity, soil organic matters and soil aggregate were the main factors to determine the soil infiltration rates. The capillary porosity and soil aggregate of the top soil presented significant negative effects on soil infiltration rate (P?<?0.05). The below-ground biomass in 10-30?cm soil layer was the most important factor, which significantly and positively correlates with the soil infiltration rate (P?<?0.01). It is possible to conclude that the legume grasslands presented the higher soil infiltration rate and promote precipitation infiltration in the studied area. And the legume grasslands might be a more suitable option for vegetation restoration from the perspective of soil infiltration and water supply in the arid regions.
... The plant functional composition and diversity can determine ecosystem productivity, stability, nutrient dynamics, by altering ecosystem function, and composition of soil carbon (C) and nitrogen (N) (Tilman, 1999;Hooper et al., 2000;van Ruijven & Berendse, 2005;Tilma et al., 2006;Fornara & Tilman, 2008). Plant diversity and soil are important contributors to primary productivity and the storages of soil C and N through complex processes (Catovsky et al., 2002;Fornara & Tilman, 2008;Steinbeiss et al., 2008;Schmidt et al., 2011;Musinguzi et al., 2015). With increasing atmospheric carbon dioxide (CO 2 ) concentrations, to sequester atmospheric C in soil is become an important ecosystem function to mitigate the increasing CO 2 (Cong et al., 2014;Turgut, 2015;Garcia-Diaz et al., 2016;Keesstra et al., 2016). ...
... Legumes had previously been identified as a key driver of primary productivity, C sequestration, N accumulation, and mineralization (Lambers et al., 2004;Fornara & Tilman, 2008). The levels of C and N in soil can also affect diversity and plant composition by increasing the amount of C and N (Ferreira et al., 2014;Shang et al., 2014;Parras-Alcántara et al., 2015;Wasak & Drewnik, 2015;Novara et al., 2016) or reducing C and N losses from soil that occurred by respiration, volatilization, and leaching (Catovsky et al., 2002;De Deyn et al., 2008;Phoenix et al., 2008). Many studies have examined how variations in functional groups and plant species richness alter the amount of soil C and N (Oelmann et al., 2007;Fornara & Tilman, 2008;De Deyn et al., 2009). ...
... Third, legumes significantly increased diversity (40%) and plant species richness (100%) in this study. The positive interactions between diversity and productivity have been well documented (Catovsky et al., 2002;Hooper et al., 2005). Compared with aboveground biomass, below-ground biomass ); BGB, Below-ground biomass (BGB, g m À2 ); R, richness index; H, Shannon-Wiener index; E, evenness index. ...
Community composition strongly affected the soil C and N storages. However, the influences of community composition on native grassland remain poorly understood. The purpose of this study is to investigate the ability of plant communities including how legumes affect the soil C and N storages in the semi-arid grassland. Experimental grassland communities were separated by whether or not containing legumes. We measured soil C and N storages and determined above-ground and below-ground biomass, litter biomass, plant species richness, and species diversity to understand the mechanisms underlying the changes of soil C and N storages and to determine the relationship of species diversity and productivity. The results showed that legumes increased above-ground and below-ground biomass and C and N storages. Soil C and N storages were significantly and positively related to above-ground and below-ground biomass, litter biomass, plant species richness, and diversity in the presence of legumes. The presence of legumes increased soil C and N simultaneously but not synchronously, which resulting in a higher C:N ratio. This study indicated that legumes increased soil C and N storages possibly through increasing biomass and soil C and N inputs. The increases are mediated by plant diversity and plant functional complementarity. We suggest that the combination of legumes-grass species may greatly enhance ecosystem services such as soil C and N storages, productivity, and diversity in semi-arid grassland.
... This context sets the stage for the question addressed here: What is the value of plant species richness in terms of carbon storage? Our approach to this question offers a quantitative monetized view of one of the values of biodiversity that contrasts with the typically qualitative nature of most other assessments of biodiversity value (18)(19)(20). Valuation also provides a quantitative foundation for assessing decisions about land use involving trade-offs (21), and, as described above, it is relevant to existing and developing carbon markets. Any exercise to place a value on species is fraught with challenges of interpretation: The service of carbon storage is but one of the many facets of a species' value, and biodiversity may have intrinsic value beyond utility for humans. ...
... Despite widespread claims about the economic value of biodiversity for ecosystem services (18)(19)(20), quantitative assessments of the relationship between biodiversity and specific services are rare. Our work demonstrates positive marginal value of species richness for carbon storage, which, by offering actual assessments of value, helps move beyond mere speculation about the economic importance of biodiversity and lends an economic argument to biodiversity preservation for climate protection. ...
Carbon storage by ecosystems is valuable for climate protection. Biodiversity conservation may help increase carbon storage, but the value of this influence has been difficult to assess. We use plant, soil, and ecosystem carbon storage data from two grassland biodiversity experiments to show that greater species richness increases economic value: Increasing species richness from 1 to 10 had twice the economic value of increasing species richness from 1 to 2. The marginal value of each additional species declined as species accumulated, reflecting the nonlinear relationship between species richness and plant biomass production. Our demonstration of the economic value of biodiversity for enhancing carbon storage provides a foundation for assessing the value of biodiversity for decisions about land management. Combining carbon storage with other ecosystem services affected by biodiversity may well enhance the economic arguments for conservation even further.
... Only a few approaches for evaluating biodiversity loss due to extraction of fish have been proposed, assessing the effects of fishing on the fertility of the ecosystem (e.g., due to disruption of food webs) and the resulting decrease of biomass (Langlois et al. 2012(Langlois et al. , 2014. Next to the evaluation of biotic resource extraction, NPP has also been used for measuring loss of biodiversity within different frameworks due to the high correlation between NPP and biodiversity (Catovsky et al. 2002;Costanza et al. 2007;Itsubo and Inaba 2012). NPP has been used to determine how many biotic resources are extracted and to quantify the decrease of the population, which is assumed to correlate with biodiversity loss. ...
... Langlois and colleagues (Langlois et al. 2012(Langlois et al. , 2014 propose to use a NPP-based indicator to account for biodiversity loss. NPP-based indicators have been used before for measuring biodiversity in different frameworks as a correlation between decreasing NPP values and when loss of biodiversity exists (Catovsky et al. 2002;Costanza et al. 2007;Itsubo and Inaba 2012). However, NPP-based indicators are not comprehensive enough to adequately assess complex impacts on biodiversity, and LSFs as interdependencies of species and ecosystems cannot be assessed properly. ...
Efficient use and consumption of natural resources is an important strategy in sustainable development. This chapter discusses available methods and indicators to assess “resource efficiency” beyond the assessment of the quantities of materials used and toward available indicators in life cycle assessment (LCA). According to the classical definition in LCA, natural resources encompass input-oriented environmental interventions (e.g., extraction of abiotic resources, such as oil, ore deposits, fossil, and fresh surface water, as well as biotic resources such as fish and trees). LCA and existing life cycle impact assessment (LCIA) methods are seen as a good basis for measuring resource efficiency. Despite several models to assess resource use and depletion within LCA, important challenges remain. Available models do not fully evaluate resource use and availability in the context of their functional relevance for human purposes. For the efficient use of resources, all dimensions of sustainability need to be addressed. Environmental, economic, and social implications of material use and availability have to also be considered. Assessment of resource utilization and efficiency associated with product systems needs to shift toward life cycle sustainability assessment (LCSA).
... There is strong evidence to support the idea that the abundance of plant species enhances an ecosystem's ability to use and transform absorbed resources into plant biomass (Cadotte et al., 2008;Cardinale et al., 2011Cardinale et al., , 2007Hooper et al., 2005). The accumulation of aboveground biomass is not always indicative of the sequestration of carbon because soil stocks hold more than 70% of the terrestrial carbon (Catovsky et al., 2002). This is especially crucial in turfgrass systems since routine mowing reduces aboveground biomass. ...
... As one example, Koteen et al. (2011) found that the replacement of perennial grasses with annual grasses was associated with decreases in SOC in California, a trend that the authors attributed to differences in biomass production, rooting depth, and water use. Beyond individual plant traits, community-level characteristics such as species richness and net primary production can also influence SOC formation and persistence (Catovsky et al., 2002;Lange et al., 2015;Chen et al., 2018). Niche complementarity and diversity of root inputs associated with elevated species richness has been linked to enhanced carbon accumulation across multiple biome types (Lange et al., 2015;Chen et al., 2018). ...
Soil organic carbon (SOC) is increasingly a focus of land management and policy initiatives, due to the dual role it plays in soil health and climate change mitigation. To manage SOC effectively, land managers would benefit from proxy indicators that can assess SOC concentrations and forecast changes through time. Because inputs and outputs to SOC are driven by plants and soil microorganisms, plant and soil microbial communities may be useful indicators of spatial or temporal SOC changes. To assess and compare the utility of these ecological communities as SOC indicators, we monitored SOC from surface and subsurface soils across a six-year period on a ranch in Central Coastal California, and measured plant, fungal, and bacterial/archaeal community composition. As expected, we observed unique relationships between each candidate indicator and SOC. Most notably, the relative abundance of putative copiotrophic and oligotrophic bacterial phyla allowed us to predict future changes in SOC concentration, as did the relative abundance of saprotrophic fungi and relative cover of perennial grass. Plant and soil microbial community structure was also related to SOC content at the time of sampling. Combining indicators improved our ability to predict SOC concentration and future changes, though we were unable to identify indicators that strongly explained historical changes in SOC concentration that preceded sampling. Our findings suggest that measurements of plant and soil microbial community structure can indicate SOC concentration and future changes, and so may be useful to inform management of healthy soils.
... The size of the NEP is more representative of long-term carbon storage across the ecosystem than plant biomass itself. Therefore, NEP is a better indicator of an ecosystem's ability to reduce anthropogenic carbon emissions [4]. ...
Net ecosystem productivity (NEP) is an important indicator for estimating regional carbon sources/sinks. The study focuses on a comprehensive computational simulation and spatiotemporal variation study of the NEP in the Yellow River basin from 2000 to 2020 using NPP data products from MODIS combined with a quantitative NEP estimation model followed by a comprehensive analysis of the spatiotemporal variation characteristics and dynamic procession persistence analysis based on meteorological data and land use data. The results show that: (1) The total NEP in the Yellow River basin had an overall increasing trend from 2000 to 2020, with a Theil–Sen trend from −23.37 to 43.66 gCm−2a−1 and a mean increase of 4.64 gCm−2a−1 (p < 0.01, 2-tailed). (2) Most areas of the Yellow River basin are carbon sink areas, and the annual average NEP per unit area was 208.56 gCm−2a−1 from 2000 to 2020. There were, however, substantial spatial and temporal variations in the NEP. Most of the carbon source area was located in the Kubuqi Desert and its surroundings. (3) Changes in land use patterns were the main cause of changes in regional NEP. During the 2000–2020 period, 1154.24 t of NEP were added, mainly due to changes in land use, e.g., the conversion of farmland to forests and grasslands. (4) The future development in 83.43% of the area is uncertain according to the Hurst index dynamic persistence analysis. In conclusion, although the carbon−sink capacity of the terrestrial ecosystem in the Yellow River basin is increasing and the regional carbon sink potential is increasing in the future, the future development of new energy resources has regional uncertainties, and the stability of the basin ecosystem needs to be enhanced.
... Moreover, higher productivity of the MS also indicates efficient utilization of resources like light, moisture, and nutrients by the diverse species in the stands with overall synergistic inter-and intra-specific interactions among the species supporting their better growth and development. This is because plant assemblages with high species diversity efficiently utilize the available resources with higher net primary production and thus higher carbon sequestration (Catovsky et al. 2002;Kirby and Potvin 2007). ...
Indisputably forest is one of the most significant natural resources and one-third of the land area of India is covered by forest which not only contributes extensively to the social and economic well-being of the rural people but also assures the sustainable growth of urban development through the preservation of the urban environment. However, in recent times, forests are being destroyed in the name of development, and the conversion of woodlands to others is an acute problem in India. At the same time, due to the lack of proper monitoring, these problems are increasing day by day. Statistical data on forest cover in India demonstrates the fact that - the destruction of forest cover largely depends on industrialization and urbanization. Asansol-Durgapur region of India is experiencing industrialization followed by urbanization in the last few decades. Though many studies have been conducted on the urban and industrial growth of the Asansol-Durgapur region, considering the importance of forest resources in the area. However, there is a substantial research gap in the study of the forest resource scenario of the study area. This study is an attempt to assess the forest resources management scenario of the Asansol-Durgapur (Industrial towns) region using geo-spatial technology. To conduct this study, satellite images of different periods for the study area have been acquired and analyzed. Different vegetation indices (e.g. Normalized Difference Vegetation Index, Soil Adjusted Vegetation Index), Land surface temperature (LST) have been derived to understand the nature and dimension of forest cover change in the study area. Supervised image classification of Landsat imageries from 1991 to 2021, measured the forest concentration in the study area, and correlated with the LST. The results show the reduction of sparse vegetation area (–34.201%), protected forest (−6.504%), and cultivated land (−26.142%), in the last 30 years. Similarly, maximum expansion is of opencast coal mining, industrial area, and, the built-up area also observed in the study area. The result also reveals that the loss of green area increases the surface temperature in Asansol and Durgapur industrial towns. Both the Asansol and Durgapur regions have recorded an increase of maximum and minimum land surface temperature from 31.64 °C to 39.64 °C and 18.83 °C to 24. °52 C respectively from 1991 to 2021. The overall study reveals that the forest cover of the study area declined due to, urbanization, and industrialization activities.KeywordsForest cover changeIndustrial townUrban green spaceLand Surface Temperature
... Moreover, higher productivity of the MS also indicates efficient utilization of resources like light, moisture, and nutrients by the diverse species in the stands with overall synergistic inter-and intra-specific interactions among the species supporting their better growth and development. This is because plant assemblages with high species diversity efficiently utilize the available resources with higher net primary production and thus higher carbon sequestration (Catovsky et al. 2002;Kirby and Potvin 2007). ...
... Increased carbon stocks in soils in response to mineral fertilization, which is principally explained by an increase in net primary productivity induced by the nitrogen inputs has been demonstrated in many studies (Catovsky et al., 2002;Knops and Tilman, 2000) and even in deeper horizons (Lorenz and Lal, 2005). In our experiment, almost all the fertilization treatments increased the grass yield with an associated increase in carbon stocks. ...
Previous long-term experiments conducted more than 10 years ago, showed that long-term application of organic fertilizer increased soil organic carbon (SOC) of grasslands. However, it was usually assumed that, independent of the successive additions of fertilizer, soils have an upper limit to their SOC due to the inability of the soil mineral phase to fix additional carbon. Andosols of the volcanic Reunion Island are typically very rich in carbon and are usually considered as saturated in SOC. To assess the long-term effect of different types of fertilization on SOC in these soils, SOC concentrations were recorded at yearly intervals for 15 years in one arenosol site and in two andosols sites across a topo-sequence. The types of fertilization tested included inorganic, organic, and a mix of inorganic and organic nutrient sources. The addition of organic fertilizers increased soil carbon in the top (0–15 cm) horizon in both the arenosol and the two andosols (up to +250% in the arenosol and up to +41% in the andosol), whereas inorganic fertilizers and the control treatment did not always result in a significant increase in SOC. After 15 years, no plateau was reached in C stocks even with the highest fertilization rates. Our results suggest that the increase in SOC was mainly caused by direct carbon inputs, while the effect of the increase in litter resulting from the increase in yield caused by fertilization, remained uncertain. In the andosol, all the fertilization treatments led to higher concentrations of carbon in the deeper layers. This suggests that SOC inputs lead to downward migration of OC to deep horizons. For C-rich soils like andosols, assessing the variations in carbon in the deep horizon is thus critical in estimating the effects of soil management on carbon sequestration.
... Bare areas in the Yellow River Delta were selected as potential offset sites, but the areas of bare land might not be enough to offset all the ecosystem services as competition for land is increasing, and policy needs to ensure the efficient supply of multiple ecosystem services from land systems. We have learned from previous studies that there is a synergistic relationship between carbon storage and biodiversity (Yang et al., 2018;Catovsky et al., 2002;Gleixner et al., 2005), as well as biodiversity and water regulation (Tockner et al., 1999;Wang et al., 2019), and a trade-off relationship between carbon storage and water regulation in coastal wetlands (Jessop et al., 2015). We discuss the scenarios by seeking to offset for the loss of: (a) carbon storage only; (b) biodiversity only; (c) water regulation only; (d) carbon storage and biodiversity; (e) carbon storage and water regulation; (f) water regulation and biodiversity; (g) carbon storage, biodiversity, and water regulation. ...
Reclamation of coastal wetlands causes the loss of multiple ecosystem services, necessitating that measures to address these impacts be taken. Offset ratios are commonly used to determine the extent of habitat areas that need to be restored elsewhere to achieve no net loss in wetlands; however, most calculation methods focus on individual impacts. In this study, a mathematical model accounting for multiple ecosystem services and their synergies or trade-offs relationships was developed to determine the required allocation of compensation area, and optimal amount of offsetting based on calculated ratios between damaged and compensated habitat areas. We took the Yellow River Delta in China as a case study, calculated the impacts on ecosystem services of different coastal reclamation types, and quantified the offset ratios for restoration based on different compensation scenarios accounting for time lags. We estimated that the offset ratios for the conversion of coastal wetlands into mariculture were smallest among all the reclamation types. We showed that compensating for carbon storage and water regulation with trade-offs will require higher offset ratios than those based on biodiversity only, and will also be more flexible. Our findings suggested that trade-offs and synergetic relationships should be prioritized when making decisions regarding the restoration of multiple ecosystem services. The findings presented herein will facilitate design of biodiversity offsets for coastal land reclamation based on their different impacts on ecosystem services. Overall, the results of this study have important implications for the ecological restoration and compensation of coastal wetlands in the face of coastal land reclamation.
... This might be attributed to the better decomposability of birch litter, resulting in a larger influx of C compounds into the mineral soil under this species compared with the conifers. However, another important factor affecting the C stock in mineral soils under the studied tree species might be differences in the production of fine roots and root exudates (Catovsky et al., 2002;Guo et al., 2007;Świątek et al., 2019;Zobel et al., 2005). In nutrientpoor forest sites, an increment of fine root biomass may deliver more organic C to soil than the litterfall (Leppälammi-Kujansuu et al., 2014). ...
Many countries are having increased frequency and severity of wildfires, including mega‐fires. The revegetation of post‐fire sites and tree species selection are the most important counteracting measure. In this study, we analyzed the effect of tree species (Scots pine, European larch, common birch) on the C stock, macronutrient content and physicochemical parameters (pH, sorption complex properties) of regenerated soil of different textures (sands and loams) in a large, post‐fire site. Nearly 30 years after the fire, soils differed among the species. The carbon stock under larch was higher in litter (Oi + Oe) horizons than under birch. In mineral horizons (0–5 cm), the C stock was highest under birch. Litter layers under birch had a higher pH, a lower C:N ratio, and higher N, P, Ca, and Mg content compared to layers under pine and larch. In the A horizons (0–5 cm), soils under birch was higher in soil organic carbon (SOC), cation exchange capacity (CEC) and acidity than soils under conifers. Soil texture in the studied range ‐ from sands to loams ‐ had only a limited effect on the properties of the studied post‐fire soils. Thus, our results indicate that the tree species used for the reforestation of post‐fire sites are crucial to the properties of regenerating soils and restoring the ecological functions of soils. Among the studied tree species, common birch had the most pronounced effect on soil properties, and this is especially significant because the species has appeared by spontaneous succession.
... soil organic carbon concentration in natural forest compared to other land-use types in the present study table 1. Catovsky et al., (2002) also stated that accumulation of carbon in soil was proportional to the biomass inputs in the soil depending on plant biodiversity. Elaborated root system of perennial trees and ground flora of natural forest might attribute more to the accumulation of soil organic carbon in natural forest as it is reported that the contribution of roots in accumulation of soil organic carbon was more compared to above ground biomass (Puget and Drinkwater, 2001). ...
The impact of land-use change on soil physicochemical properties was studied through upper (0-10 cm), middle (10-20 cm) and lower (20-30 cm) soil layer during summer season involving natural forest, degraded forest, agro ecosystem, and Jatropha curcas plantation. Land-use change from natural forest to agro ecosystem, had negative impact on soil organic carbon, total nitrogen, porosity, bulk density and water holding capacity. J. curcas plantation on cleared patches of degraded forest increased soil organic carbon, total nitrogen, porosity, water holding capacity but decreased soil bulk density compared to degraded forest and agro ecosystem at all the soil depths. It is suggested that Jatropha curcas plantation improved various soil physicochemical properties that were rendered disproportionate during land use changes. Hence it may be adopted as the alternative for restoration of degraded lands.
... L'avantage du choix des espèces est de pouvoir assurer de la diversité et ainsi améliorer la résistance de l'écosystème aux perturbations (Isbell et al., 2015). La formation du Mull permet alors la mise en place de boucles de rétroaction, telles que l'augmentation annuelle de la production primaire nette (Desie et al., 2020;Zanella et al., 2017a) donc du stockage de carbone dans le sol (Catovsky et al., 2002). Elle entraine également une augmentation annuelle de l'épaisseur de l'humipedon et la création de niches écologiques, permettant un niveau élevé de biodiversité dans les sols (Ponge, 2003). ...
Dans un contexte de dégradation des sols suite aux activités anthropiques et d’érosion de la biodiversité, la compréhension du rôle de la faune édaphique dans le fonctionnement des humipedons est d’intérêt croissant. Le développement de stratégies de réhabilitation des sols anthropisés basées sur les concepts de l’ingénierie écologique pourrait notamment s’appuyer sur les actions de transformation des matières organiques que réalisent les organismes saprophages. L’objectif de cette thèse était (i) de caractériser les fonctions écologiques réalisées par les organismes saprophages à travers la production de biostructures sur des sols fortement anthropisés et (ii) d’évaluer leur potentialité de réhabilitation des Technosols de friches industrielles. Pour cela, une démarche intégrative, basée sur le changement d’échelle spatiale, a été menée sur une friche industrielle d’intérêt. Dans un premier temps, il a été mis en évidence que les caractéristiques physico-chimiques des substrats de Technosols peuvent représenter un filtre abiotique pour la colonisation de la faune édaphique, qui se traduit notamment par l’absence de lombricidés anéciques et endogés dans les Technosols. Dans un deuxième temps, à l’échelle de l’humipedon, les résultats ont permis de montrer que la dynamique des matières organiques néoformées par la végétation dépend également de la nature du substrat utilisé lors de la réhabilitation de la friche. En effet, sous l’action des saprophages épigés, une série d’horizons ectorganiques, similaire à celle d’un Moder, s’est développée sur l’horizon technogénique des Technosols. Le terme de « Techno-moder » a ainsi été proposé pour décrire cette nouvelle forme d’humus. Les spécificités chimiques et ultrastructurales de l’horizon zOH du Techno-moder, constitué de biostructures produites par les saprophages, ont également confirmé cette proposition de classification. Pour finir, l’étude en conditions contrôlées des déjections produites par l’isopode saprophage Porcellio scaber a permis de mettre en évidence que les traits physico-chimiques des déjections dépendent du substrat composant le Technosol et de la matière organique apportée. En accord avec ce qui avait été conclu à l’échelle de l’humipedon, il semble donc que les traits des déjections produites par les saprophages épigés soient une caractéristique intrinsèque de l’écosystème, qui résulte des facteurs environnementaux caractérisant l’humipedon des Technosols. Le développement de stratégie de réhabilitation des Technosols par inoculation couplée de saprophages et de matières organiques pourrait ainsi améliorer certaines caractéristiques physico-chimiques des humipedons de Technosols tout en imposant la prise en compte des interactions spécifiques des organismes avec le substrat.
... Agricultural and urban sources that emit NH 3 directly or indirectly through atmospheric deposition processes (Howarth et al., 1996;Ryan & Boyer, 2012) are known to alter the structure and functions of salt marshes (Geoghegan et al., 2018). Furthermore, atmospheric deposition processes have been identified as the main route of entry for NH 3 into coastal waters (Paerl & Fogel, 1994), and the deposition of NH 3 to sensitive ecosystems (e.g., salt marshes) can lead to a series of negative effects such as soil acidification, eutrophication and loss of biodiversity (Catovsky et al., 2002;Wallace et al., 2014). ...
Measurements of atmospheric ammonia (NH3) concentrations and fluxes are limited in coastal regions in the eastern U.S. In this study, continuous and high temporal resolution measurements (5s) of atmospheric NH3 concentrations were recorded using a cavity ring-down spectrometer in a temperate tidal salt marsh at the St Jones Reserve (Dover, DE). Micrometeorological variables were measured using an eddy covariance system which is part of the AmeriFlux network (US-StJ). Soil, plant, and water chemistry were also analyzed to characterize the sources and sinks of atmospheric NH3. A new analytical methodology was used to estimate the average ecosystem-scale diurnal cycle of NH3 fluxes by replicating the characteristics of a chamber experiment. This virtual chamber approach estimates positive surface fluxes in continuing strongly stable conditions when mixing with the air above is minimal. Our findings show that tidal water level may have a significant impact on NH3 emissions from the marsh. The largest fluxes were observed at low tide when more soil was exposed. While it is expected that NH3 fluxes will peak when the air temperature maximizes, high tide occurred concurrently with midday peaks in solar irradiance led to a decrease in NH3 fluxes. Furthermore, soil, plant, and water chemistry measurements underpinning the NH3 concentrations and fluxes lead us to conclude that this coastal wetland ecosystem can act as either a sink or a source of NH3. Such measurements provide novel data on which we can base reliable parameterizations to simulate NH3 emissions from coastal salt marsh ecosystems using surface-atmosphere transfer models.
... All types of biodiversity cannot be captured through two metrics and thus, their interpretation might overlook impacts to ecosystem health (Mcgill et al., 2015). It is also important to keep in mind that complementary metrics for biodiversity are correlated to some extent because the different biodiversity types influence each other (Naeem et al., 1996;Haberl, 1997;Catovski, et al., 2002). To avoid potential double counting, these two complementary indicators should not be combined into an aggregated single metric. ...
To sustain the needs of growing world population, seas and oceans are becoming heavily exploited. Initially exploited for food and transportation, offshore marine areas are nowadays supplying energy and minerals. Whilst the extraction of terrestrial natural resources led to major environmental consequences (i.e. biodiversity loss), it is crucial to ensure the global environmental sustainability of marine products on their entire life cycle. Life Cycle Assessment (LCA) methods have the potential to provide such information and to identify hotspots of environmental impacts in the value chain of the product under analysis. At the endpoint level, LCA results consider impacts on three areas of protection (AoP): human health, ecosystem quality and natural resources. However, LCA methods have been traditionally applied to industrial processes and thus, are limited to include site-specific aspects (e.g. disturbance of the local ecosystem) in the scope of the assessment. The application of LCA to assess the environmental sustainability of marine products including ecosystem-specific life cycle impact assessments (LCIAs) in the evaluation of impacts belonging to the three AoP. Moreover, quantitative data on mass and energy flows associated to the entire life cycle of the products (production / extraction of raw materials and their processing to final commodities) are required to perform global environmental sustainability assessments. The overall objective of this PhD is to reinforce LCA capacity to assess the global sustainability of marine products. Two operational frameworks are proposed to include site-specific aspects related to the sourcing of marine raw materials, and data related to the processing of wet biomass are provided. In this way, the evaluation of the global environmental sustainability of marine products through LCA will be more inclusive and meaningful for comparative assessments with terrestrial alternatives. The PhD starts with a general introduction (Chapter 1) divided into four sections. First, an overview of marine activities is provided. The most important marine activities in terms of economic importance are described and the concept of the industrial revolution of the seas and oceans is introduced. This refers to the growing importance of the marine-sourced materials and energy for the global economy. Indeed, the importance of the marine economy is expected to follow a two-fold increase by 2030. On a longer time horizon, the potential recovery of deep-sea minerals might significantly increase our dependence on marine commodities. The second section provides background information related to the classification of natural resources and their link with ecosystem services. Natural resources are classified according to renewability, exhaustibility and their form at the moment of extraction (biotic / abiotic). Marine natural resources are presented according to this classification and in the context of ecosystem services. Deep-sea minerals are extensively presented as they might become substantial for our economy in a near future. The ecological pressures on marine ecosystems are discussed in the third section. Direct drivers of impact caused by the marine economy are highlighted, such as the reduction of commercial fish stock size. The fourth section introduces the global concepts of LCA and the development of site-specific LCIA pathways to assess changes in local ecosystem quality, measured through biodiversity related metrics. The main limitations for global environmental sustainability assessments of marine products are exposed. The needs for site-specific marine LCIAs and further data regarding the processing of marine raw materials are highlighted. Chapter 2 quantifies trade-offs amongst seaweed farming and wild catches fisheries. Both are considered as marine natural resources and marine ecosystem services. The reduction in fisheries yields caused by the harvesting of net primary production (NPP) (i.e. seaweed) is estimated through a trophic food web approach. A site-specific LCIA framework relying on the seasonal ecosystem NPP, seaweed biomass growth and fish landings is proposed to assess the Lost Potential Yield (LPY) of the area under study. LPY are reported in terms of biomass, economic value and eco-exergy, a metric measuring the genomic complexity of the organisms. The framework is illustrated for the Greater North Sea and shows a net positive contribution of seaweed farming in terms of marine natural resources (i.e. the production of seaweed exceeds the decrease in fisheries landings for the three LPY metrics). Further research could consist in the development of additional impact pathways to NPP reduction (e.g. habitat provision) and on the consideration of ecosystem carrying capacity. The following chapter (Chapter 3) develops a site-specific LCIA framework to assess impacts of deep seafloor disturbance on regional and global biodiversity as proxy for ecosystem quality. Changes in ecosystem quality are measured through a biodiversity-related metric: the potentially disappeared fraction of species (PDF), expressing relative changes in species richness caused by the intervention. The framework builds on existing LCIAs assessing impacts on ecosystem quality from land-use (i.e. land transformation and occupation). According to existing literature, the framework identifies three kinds of impacts: transformation, occupation and permanent impacts that can be summed to obtain the total impact on regional and global ecosystem quality. The regional biodiversity impacts are first assessed and converted to global biodiversity impacts considering the vulnerability and the scarcity of the ecosystem impacted. The framework is operationalized in a case study consisting to polymetallic nodules mining in the Clarion Clipperton Fracture Zone (CCZ). Despite the very limited knowledge on benthic recovery from deep-sea mining, the framework shows consistency with existing LCA characterization models for biodiversity. The total impact on regional and global biodiversity is mostly influenced by the permanent impact on biodiversity because of the absence of recovery of a significant fraction of species. This framework can be integrated into LCA studies in order to understand the global environmental sustainability of deep-sea activities. Next to the development of additional LCIAs, the availability of detailed and transparent datasets is another challenge to assess the global environmental sustainability of marine products. Chapter 4 computes mass and energy flows associated with the harvesting and the processing of microalgae under eight biorefinery scenarios to produce lipids, proteins, energy and dried biomass. Two cell disruption methods are tested and two solvents for lipid extraction are compared. Complete flowsheets are provided for each step of the downstream processing of the raw biomass. The chapter highlights the impact of the cell disruption method on the total energy demand but also, the influence amongst downstream processes in a cascade design. Lipid extraction has influence on protein extraction, this latter improving energy production as it has a more favourable carbon to nitrogen ratio. In addition, lipids are extracted with a conventional solvent (hexane) for some scenarios and with a biobased solvent (2-methytetrahydrofuran) for other scenarios. The azeotropic distillation required for the recovery of the biobased solvent (and thus its extra energy demand) shows that solvent selection is crucial to control the total energy demand of the process, but lipid profiles will vary according to solvent properties. The last chapter (Chapter 5) consists of the conclusions and perspectives of the manuscript. Whilst the conclusions discuss the main outcomes of the three (published) research chapters (Chapter 2, Chapter 3 and Chapter 4), the perspective section opens a discussion on the requirement for an exhaustive classification of marine ecosystems. In a similar way as for the terrestrial ecosystems, such classification will facilitate the development of databases for marine ecosystem attributes and hence, the implementation of site-specific LCIAs. Furthermore, the section discusses alternatives to species richness related metrics to monitor changes in the ecosystem quality. Different types of biodiversity are defined according to the combination of biodiversity level (i.e. genetic, species, communities and landscape) and biodiversity attribute (i.e. composition, structure, function). Consequently, it is not possible to grasp the entire complexity of biodiversity through a single indicator such as species richness in LCA methods. The use of potential additional indicators for ecosystem quality and the main challenges arising from it are discussed. Finally, the discussion highlights the importance of aligning the scope of LCA studies with the descriptors used by European policy makers to assess the environmental status of marine ecosystems (under the Marine Strategy Framework Directive, MSFD). It emphasizes the needs for additional marine LCIAs to consider all descriptors identified by the MSFD (11) in LCA studies of marine products. The challenge of integrating marine ecosystem services in the scope of LCA studies is considered. Because of the complexity of quantifying ecosystem services and their link with biodiversity, the use of regional biodiversity as midpoint indicator for ecosystem services is proposed. Finally, the section concludes by discussing the challenge of evaluating the total cumulative impact caused by different stressors on a given marine ecosystem. Whilst existing LCIAs do not consider interactions amongst each other, it is relevant to make use of ecological risk assessment tools to model the final ecosystem response to various disturbances occurring in parallel. To conclude, this work has emphasized two main challenges for the global environmental sustainability assessment of marine products: the implementation of site-specific LCIA frameworks and the development of datasets regarding further processing of the harvested products.
... Studies have established functional relationships between plant diversity and carbon storage [71][72][73][74][75][76][77][78][79] and higher carbon storage of MS than the species-dominated stands indicate this relationship. Higher plant assemblages with many species in the MS diversity resulted in a higher resource use efficiency, with higher productivity, litter production, and SOC than the species-dominated stands [80][81][82]. The soil in all the stands at all depths was high in organic carbon [57] due to higher litter production by the stands, adding corresponding amounts of OM in the soil. ...
In recent decades, carbon (C) management is an important point on the agenda to identify
the best viable mitigation strategies for its reduction. The study was conducted at Jaldapara National Park located in the Eastern Himalayan region of India. The study quantified litter production, decomposition, periodic nutrient release, soil fertility status, and soil organic carbon (SOC) of five major forest stands i.e., Tectona grandis (TGDS), Shorea robusta (SRDS), Michelia champaca (MCDS), Lagerstroemia parviflora (LPDS) and miscellaneousstand (MS). A stratified random nested quadrate method was adopted for sample collection. Results reveal that the greatest amount of litter production and decomposition was under MCDS followed by MS, LPDS, SRDS, and the smallest under TGDS. The material annual turnover through litter decomposition in all the stands varies between 96.46% and 99.34%. The content and amount of the available nutrients in litter varied significantly among the stands. Moreover, release of these nutrients was nearly equal to the amount available in the initial litter mass. In general, the magnitude of the total nutrient return was in the same order as the total litter fall and the nutrient availability was more closely related to litter nutrient content and soil organic carbon. The range of pH (4.86–5.16), EC (0.34–0.50), soil moisture (27.01–31.03) and available primary nutrients (N: (0.21–0.26 Mg/ha), P: (0.09–0.12 Mg/ha), K: (0.13–0.14 Mg/ha)) also varied
significantly among the stands. Significant positive correlations were observed between SOC, N and K. Both the fertility indices exhibited no definite pattern in the stands but a significant correlation between the two indicates the healthy soil fertility status of the stands. SOC varies significantly under different forest stands, but the greatest content was found under MS. The estimated SOC ranges between 75.9 and 107.7 Mg ha1 up to 60 cm and is reported to be below the Indian average of 182.94 Mg ha1. The present study strongly recommends that Tectona grandis, Shorea robusta, Michelia champaca, and Lagerstroemia parviflora should be the important commercial timbers of the Eastern Himalayan region because they may help further to increase the C sink in agricultural and
degraded landscapes.
... Our results demonstrated that an increase in litter cover would reduce biocrust cover, particularly over 30% of litter cover (Fig. 2c). Despite the positive association between the overstorey plant community and litterfall, litter cover is more likely related to site-level ecosystem productivity (Catovsky et al. 2002), which is regulated by large-scale environmental factors such as rainfall and temperature. For example, we found that the suppressive effect of litter cover was mediated as sites become more arid. ...
AimsBiocrusts are globally distributed and important for sustaining critical ecosystem functions. Little is known about their continental drivers and how smaller-scale microsite differences might affect biocrusts along aridity gradients. This limits our ability to manage biocrusts effectively under drier climates.Methods
We collected data on biocrust cover, biotic (plants, litter, grazing intensity) and abiotic (soil texture, soil stability and integrity) attributes from four microsites (trees, shrubs, grasses, open) at 150 sites along an extensive aridity gradient in eastern Australia.ResultsAt the sub-continental scale, average biocrust cover increased with declining litter cover, and crust cover became more variable with increasing aridity. Biocrust cover was greatest in open microsites and least under trees, and differences were related to the effects of soil texture, vegetation and grazing intensity, which either increased or declined with increasing aridity.Conclusions
Our study reveals that biotic and abiotic effects on biocrust cover vary at different spatial scales along an aridity gradient. Predicted increases in aridity in eastern Australia will likely enhance biocrust cover whereas microsite-level effects are likely to be driven by land management actions such as vegetation removal and overgrazing.
... The expanded root system of perennial trees and grasses, lack of tillage and livestock addition also contributed more in organic carbon storage (Singh et al. 2009) in these land-use types. It has been reported that organic carbon present in soil is proportional to biomass addition which in turn is dependent on biodiversity of that area (Catovsky et al. 2002, Lambers et al. 2004. ...
Conversion of forest land into different land use types is the primary cause of degradation of land resources, which in turn alters nutrient and carbon cycles, land productivity and diversity of species. There is scarcity of information about land-use changes (LUC) and their effect on relationship of soil quality and species diversity at landscape level in the Vindhyan dry tropical region. We evaluated the impact of land-use changes on soil physicochemical quality and the influence of these qualities on species diversity and organic matter accumulation. We also established the relationship between soil quality indicators and species diversity parameters. To examine impact of LUC, we did a detailed field survey and analysed selected soil quality indicators by standard methods. We examined species diversity parameters and established the relationship between soil quality and species diversity. We found that there is a marked decline in soil porosity, water-holding capacity and soil moisture due to LUC. Conversion from forest land (FL) to savanna land (SL) resulted in soil organic carbon decreasing by ∼40–50%. The decrease was more pronounced in cultivated land (CL) and degraded land (DL) (65–70% and 83–85%, respectively). In the case of total N, maximum decrease in total N of 83–87% was noted in DL as compared with FL. The poor soil quality indicators in degraded and agricultural land can be explained by the interaction between the soil organic carbon and nitrogen loss with diversity loss. This study recommends that for management/restoration of land resources, planning strategies should consider the current landscape structure, with land-use planning.
... Hungate et al. (2017) reported that carbon storage is one of the many features of a species value. However, currently, there is little known how plant diversity influences carbon storage in ecosystems including above-and below-ground biomass as well (Catovsky et al. 2002). Moreover, only some studies determinate carbon storage in root biomass. ...
This paper aimed to monitory the dry matter biomass production and carbon stocks of above-and below-ground biomass in five types of grasslands in Slovakia: i) lowland oversowed pasture ii) lowland hay meadows, iii) mesophilous pasture, iv) mountain hay meadows, v) abandoned grassland. Averaged over two cropping seasons the total above-and below-ground biomass differed significantly across the monitored grasslands. It ranged respectively from 2.18 to 7.86 t/ha and from 9.64 to 22.67 t/ha dry matter depending on the pedoclimatic condition and the botanical composition of each grassland type. Consequently, this resulted also in the carbon stocks in above-and below-ground biomass. Generally, the mean carbon stocks were 1.56 t/ha for above-ground biomass (24%) and 4.83 t/ha for below-ground biomass (76%). The botanical composition for all the grassland types was also described. The highest number of plant species (55) was observed in lowland hay meadow located in Slovak Karst, the lowest one (23) for the oversowed grassland located in Eastern Slovak Upland. This monitoring paper showed that semi-natural grassland habitats and improved grasslands as well are an important carbon sink, and they can play a key role in global climate change mitigation.
... Tilman et al. ,1997;Davidson & Jans鄄 sens,2006;徐小锋等,2007;Nair et al. ,2009) ,所以 不同的环境变量对不同生态系统土壤碳储量的影响 也不同( 解宪丽等,2004) 。 与同一区域内的热带季 节雨林相比( 吕晓涛等,2006) ,西双版纳勐海地区 不同茶园类型的土壤碳储量则高于热带季节雨林的 土壤碳储量,其原因可能是其所处的相对海拔更高, 由此所造成的水热差异所导致的生物地球化学循环 较慢。 此外,茶园生态系统较高的修剪物归还量也 是其土壤碳储量较高的另一个重要原因( Li et al. , 2011) 。 物种多样性通过影响碳积累和损失的速率,碳 库的大小及其稳定性,而影响多物种组成的复合生 态系统的碳储存能力(Catovsky et al. ,2002;Bunker et al. ,2005;Diaz et al. ,2009;Potvin et al. ...
... In order to address and mitigate damage to forest habitats caused by mushroom harvesting, it is imperative to develop feasible management plans, based on sound ecological understanding and knowledge of biodiversity within any given system [10][11][12]. Catovsky et al. [13] proposed that the study of biodiversity at the ecosystem level should be a priority for ecological research, especially applicable for the study of the diversity and distribution of macrofungi in sensitive areas. ...
The Greater Mekong River Subregion (GMS) is a global biodiversity hotspot. Macrofungi play an essential role as decomposers, parasites, and symbionts, and are also an important source of medicine, food, and income for many communities in the GMS; however, the diversity and composition of macrofungi in this region remain poorly understood. In order to help address this knowledge gap, we established 20 permanent study plots in the GMS (native forests, tea plantation, pine plantations, mixed rubber and coffee plantation). Macrofungal diversity and community composition were evaluated across four study sites classified to two climate types and two management methods. Heat maps and nonmetric multidimensional scaling (NMDS) were used to show differences in macrofungal community composition, and linear relationships were illustrated in order to analyze how environmental factors influenced macrofungal diversity and community composition. In total, 7028 specimens were collected, belonging to 1360 species, 216 genera, and 79 families. Russula, Lactarius, Amanita, Mycena, Suillus, and Inocybe were found to be the dominant genera in the GMS. We found that ectomycorrhizal fungi were dominant in temperate forests and that saprobic fungi were dominant in tropical forests. We also found that macrofungal community composition in native forests differed from that of plantation forests, indicating that plantations can provide different and complementary habitats formacrofungal growth. Our analysis of environmental factors revealed that macrofungal diversity was weakly correlated with tree species richness, and strongly correlated with elevation and latitude.
... Yet, the role that plant diversity plays in plant litter decomposition remains elusive Gessner et al. 2010). The decomposition of plant litter drives nutrient and carbon (C) cycling in terrestrial ecosystems and therefore is important for primary production and soil C sequestration (Catovsky, Bradford & Hector 2002;Berg & McClaugherty 2008;Lange et al. 2015). Making up the majority of the plant standing biomass especially in grasslands (Jackson et al. 1996;Poorter et al. 2012), roots constitute a substantial portion of plant litter input . ...
... Yet, the role that plant diversity plays in plant litter decomposition remains elusive (Hättenschwiler et al. 2005;Gessner et al. 2010). The decomposition of plant litter drives nutrient and carbon (C) cycling in terrestrial ecosystems and therefore is important for primary production and soil C sequestration (Catovsky et al. 2002;Berg and McClaugherty 2008;Lange et al. 2015). Making up the majority of the plant standing biomass especially in grasslands (Jackson et al. 1996;Poorter et al. 2012), roots constitute a substantial portion of plant litter input into soils (Freschet et al. 2013). ...
(Access to full-text: http://rdcu.be/v035) Plant diversity influences many ecosystem functions including root decomposition. However, due to the presence of multiple pathways via which plant diversity may affect root decomposition, our mechanistic understanding of their relationships is limited. In a grassland biodiversity experiment, we simultaneously assessed the effects of three pathways—root litter quality, soil biota, and soil abiotic conditions—on the relationships between plant diversity (in terms of species richness and the presence/absence of grasses and legumes) and root decomposition using structural equation modeling. Our final structural equation model explained 70% of the variation in root mass loss. However, different measures of plant diversity included in our model operated via different pathways to alter root mass loss. Plant species richness had a negative effect on root mass loss. This was partially due to increased Oribatida abundance, but was weakened by enhanced root potassium (K) concentration in more diverse mixtures. Equally, grass presence negatively affected root mass loss. This effect of grasses was mostly mediated via increased root lignin concentration and supported via increased Oribatida abundance and decreased root K concentration. In contrast, legume presence showed a net positive effect on root mass loss via decreased root lignin concentration and increased root magnesium concentration, both of which led to enhanced root mass loss. Overall, the different measures of plant diversity had contrasting effects on root decomposition. Furthermore, we found that root chemistry and soil biota but not root morphology or soil abiotic conditions mediated these effects of plant diversity on root decomposition.
... Recent experimental evidence demonstrates that the type and diversity of plant species in grasslands plays an important role for carbon transfer into the soil and is able to modify carbon storage under a given land use scheme (Tilman et al., 2006;Steinbeiss et al., in press). As higher plant biodiversity leads to larger plant biomass (Lambers et al., 2004;Roscher et al., 2005;Balvanera et al., 2006) and therefore a larger biomass input into the soil, it is generally assumed that differences in input amounts (not quality of the input material) are responsible for the observed variation in soil carbon storage (Catovsky et al., 2002;Skinner et al., 2006). Soil microorganisms, however, might be especially activated by the input of fresh and easily decomposable plant material if a higher plant diversity increases the variability of compounds available as a nutrient source (Wardle et al., 1999;Hooper et al., 2000;Stephan et al., 2000). ...
We investigated the fate of root and litter derived carbon into soil organic matter and dissolved organic matter in soil profiles, in order to explain unexpected positive effects of plant diversity on carbon storage. A time series of soil and soil solution samples was investigated at the field site of The Jena Experiment. In addition to the main biodiversity experiment with C3 plants, a C4 species (Amaranthus retroflexus L.) naturally labeled with 13C was grown on an extra plot. Changes in organic carbon concentration in soil and soil solution were combined with stable isotope measurements to follow the fate of plant carbon into the soil and soil solution. A split plot design with plant litter removal versus double litter input simulated differences in biomass input. After 2 years, the no litter and double litter treatment, respectively, showed an increase of 381 g C m−2 and 263 g C m−2 to 20 cm depth, while 71 g C m−2 and 393 g C m−2 were lost between 20 and 30 cm depth. The isotopic label in the top 5 cm indicated that 11 and 15% of soil organic carbon were derived from plant material on the no litter and the double litter treatment, respectively. Without litter, this equals the total amount of carbon newly stored in soil, whereas with double litter this corresponds to twice the amount of stored carbon. Our results indicate that litter input resulted in lower carbon storage and larger carbon losses and consequently accelerated turnover of soil organic carbon. Isotopic evidence showed that inherited soil organic carbon was replaced by fresh plant carbon near the soil surface. Our results suggest that primarily carbon released from soil organic matter, not newly introduced plant organic matter, was transported in the soil solution and contributed to the observed carbon storage in deeper horizons.
... These analyses summarize and parse over 20 yr of plot, greenhouse, and mesocosm studies in which species diversity was directly manipulated to determine how ecosystem functions, including productivity, were affected. Aboveground biomass accumulation is not always representative of C sequestration, as greater than 70% of terrestrial C is retained in soil stocks (Catovsky et al., 2002). This is of particular importance in turfgrass systems where mowing regularly removes aboveground biomass. ...
In the United States, there is a growing need for turfgrass management practices that protect community and environmental health. The proportion of the developed landscape in the United States covered by turfgrass is significant and, at present, covers at least 1.9% of the total land area and comprises 60% in parts of the country. As urbanization progresses, there is a critical need to re-examine turf management practices that reduce reliance on pesticide and fertilizer inputs while contributing additional beneficial ecosystem services. In this review, we discuss the functional role of turfgrass in urban ecosystems. We identify key urban ecosystem processes associated with turfgrass and evaluate the potential to integrate biodiversity into their design and management. Specifically, we summarize research on the Biodiversity and Ecosystem Function theory that shows enhanced C storage, N retention, and weed suppression in natural and managed ecosystems, which are traits that are relevant to turfgrass systems. Enhancing biodiversity in turfgrass systems could increase ecosystem services in urban landscapes and should be considered a component of sustainable management practices.
... One of the possible explanations that account for this lower loss rate of leaf-assimilated C is associated with decreased aboveground respiration in the 12Y. Previous studies reported that higher plant diversity mitigated C losses 53,54 , and a recent study demonstrated lower aboveground respiration for the perennial artificial grass (with higher biodiversity) than for the annual artificial grass (with lower biodiversity) on the Qinghai-Tibetan Plateau 18 . Alternatively, in all three artificial grasslands, E. nutans and P. annua were two of the fast-growing plant species, and these grasses were shown to have small root-shoot ratios. ...
Artificial grasslands play a role in carbon storage on the Qinghai–Tibetan Plateau. The artificial grasslands exhibit decreased proportions of graminate and increased species richness with age. However, the effect of the graminate proportions and species richness on ecosystem C stocks in artificial grasslands have not been elucidated. We conducted an in situ¹³C pulse-labeling experiment in August 2012 using artificial grasslands that had been established for two years (2Y), five years (5Y), and twelve years (12Y). Each region was plowed fallow from severely degraded alpine meadow in the Qinghai-Tibetan Plateau. The 12Y grassland had moderate proportions of graminate and the highest species richness. This region showed more recovered ¹³C in soil and a longer mean residence time, which suggests species richness controls the ecosystem C stock. The loss rate of leaf-assimilated C of the graminate-dominant plant species Elymus nutans in artificial grasslands of different ages was lowest in the 12Y grassland, which also had the highest species richness. Thus the lower loss rate of leaf-assimilated C can be partially responsible for the larger ecosystem carbon stocks in the 12Y grassland. This finding is a novel mechanism for the effects of species richness on the increase in ecosystem functioning.
... The following nine parameters are indicators of the photosynthetic activity of green algae (Krüger et al., 1997;Perron and Juneau, 2011;Rapacz, 2007;Rodea-Palomares et al., 2012;Strasser et al., 2000): RC per absorption flux, RC/ABS; RC per trapped energy flux, RC/TRo; electron transport flux per RC, ETo/RC; RC per dissipated energy flux, RC/Dio; maximum quantum yield of primary photochemistry, Fv/Fm; quantum yield of electron transport, ETo/ABS; quantum yield of energy dissipation, Fo/Fm; average quantum yield of primary photochemistry, Fv/Fm (Sm/t FM ); and total complementary area between chlorophyll fluorescence transients and F ¼ Fm, area. As primary producers in aquatic and terrestrial ecosystems, the productivity of algae via photosynthesis is a very important mechanism (Black, 1971;Catovsky et al., 2002;Williams et al., 2000). ...
Although fluoride occurs naturally in the environment, excessive amounts of fluoride in freshwater and terrestrial ecosystems can be harmful. We evaluated the toxicity of fluoride compounds on the growth, viability, and photosynthetic capacity of freshwater (Chlamydomonas reinhardtii and Pseudokirchneriella subcapitata) and terrestrial (Chlorococcum infusionum) algae. To measure algal growth inhibition, a flow cytometric method was adopted (i.e., cell size, granularity, and auto-fluorescence measurements), and algal yield was calculated to assess cell viability. Rhodamine123 and fluorescein diacetate were used to evaluate mitochondrial membrane potential (MMA, ΔΨm) and cell permeability. Nine parameters related to the photosynthetic capacity of algae were also evaluated. The results indicated that high concentrations of fluoride compounds affected cell viability, cell organelle potential, and photosynthetic functions. The cell viability measurements of the three algal species decreased, but apoptosis was only observed in C. infusionum. The MMA (ΔΨm) of cells exposed to fluoride varied among species, and the cell permeability of the three species generally decreased. The decrease in the photosynthetic activity of algae may be attributable to the combination of fluoride ions (F⁻) with magnesium ions (Mg²⁺) in chlorophyll. Our results therefore provide strong evidence for the potential risks of fluoride compounds to microflora and microfauna in freshwater and terrestrial ecosystems.
... As capoeiras e os SAFs apresentaram maior diversidade total de espécies que os sistemas agrícolas e as pastagens (Figura 1). Catovsky et al. (2002) afirmam que quanto maior a diversidade de espécies em um determinado ecossistema, maior será o potencial de estoque de carbono na biomassa, em função da otimização da fotossíntese das diferentes espécies que compõem o ecossistema. Desta forma, os SAFs multiestrata, por sua diversidade horizontal e vertical, tendem a proporcionar estoques de carbono similares a ambientes naturalmente biodiversos. ...
p>Carbon storage of agroforestry systems, regenerated areas, conventional agriculture and pasture was evaluated at Alto Ribeira Valley region, São Paulo State, Brazil, in different compartments of Land-use systems (LUS). In soil, classified as Entisols and Inceptisols, we found similarities among all LUS, dued to their low contents of organic carbon, and similar values of bulk density. The total carbon stocked on land-use systems, greater amounts were determined on regenerated areas (115.78 Mg ha-1), followed by agroforestry systems (75.38 Mg ha-1), agriculture (47.07 Mg ha-1), and pasture (36.01 Mg ha-1). Despite their conservative characteristic, the silvicultural practices of multistrata agroforestry systems have to be improved for forest production and carbon sequestration.
doi: 10.4336/2011.pfb.31.66.143
Foi avaliado o estoque de carbono no solo, serapilheira, biomassa arbórea e biomassa herbácea de SAFs multiestratos, em comparação a capoeiras em diferentes estágios de regeneração, sistemas agrícolas convencionais e pastagem, todos na região do Alto Vale do Ribeira, SP. Nos Neossolos e Cambissolos, com baixos teores de carbono orgânico e similaridade dos valores de densidade aparente, as capoeiras contribuíram com 115,78 Mg ha-1 de carbono total estocado, seguidas dos SAFs (75,37 Mg ha-1), das áreas agrícolas (47,07 Mg ha-1) e das pastagens (36,01 Mg ha-1). Apesar do grande potencial de sequestro de carbono dos SAFs, há necessidade de melhoria em suas práticas silviculturais.
doi: 10.4336/2011.pfb.31.66.143
</p
... While there is consensus that the increasing loss of biodiversity within terrestrial ecosystems is likely to reduce the stability of aboveground ecosystems (Tilman et al., 2001;Catovsky et al., 2002;Hooper et al., 2005), only a small number of studies have investigated the impact of plant diversity on belowground biota and soil functioning. The mechanisms underpinning processes such as soil C stabilization, especially in relation to above-ground plant diversity, are not well understood (Wardle et al., 2004;Kielak et al., 2008;Cardinale et al., 2012;Lange et al., 2014). ...
Rising atmospheric CO2 concentration and global mean temperatures have stimulated interest in managing terrestrial systems to sequester more carbon and mitigate climate change. In a restored prairie experiment, we compared high diversity (HD, 25 species) with low diversity (LD, 6 species) prairies to investigate the effect of plant diversity on soil microbial communities and their residues with soil depth. We assayed lipid and amino sugar biomarkers for soil samples, taken after 9 years following the establishment of the prairie treatment, at 5 depth increment layers: 0–2 cm, 12–15 cm, 25–27 cm, 50–52 cm, and 98–100 cm. We found that the microbial biomass and residues decreased considerably with depth in both diversity treatments. Ordination analysis of lipid profiles indicated soil microbial communities were consistently distinct between the deeper and the upper layers, regardless of treatment, and also differed between the LD and HD treatments. Plant diversity effects on soil microbial communities strongly correlated with arbuscular mycorrhizal fungi (AMF), as indicated by the lipid marker 16:1ω5c. Soil microbial residues in deeper horizons were relatively more enriched in HD than LD treatments, suggesting that greater plant diversity might sustain higher soil carbon storage through relatively recalcitrant necromass inputs in the long term. Decreasing glucosamine/muramic acid (GluN/MurA) ratio in LD and increasing in HD with depth suggested that the new microbially-accumulated carbon was positively contributed by fungal-derived residues. Our results indicate that plant diversity drives soil microbial carbon sequestration through changes in AMF abundance in restored native tallgrass ecosystems. These findings have implications for understanding how the management of plant diversity can improve soil quality and sustainability in grasslands, and how efforts to conserve and restore diverse grasslands could mitigate greenhouse gas emissions.
... Hedgerow type or plant species selection may also play an important role in mediating GWP. Tree species selection ) and overall species diversity (as hypothesized by Catovsky et al. 2002) can influence the quantity of soil C inputs, temperature and moisture (Jabro et al. 2008) and thus soil CO 2 emissions from heterotrophic respiration. Hedgerow type could also change hydrologic conditions on the farm and thus impact CH 4 emissions. ...
Planting hedgerows on farm field edges can help mitigate greenhouse gas (GHG) emissions from agricultural landscapes by sequestering carbon (C) in woody biomass and in soil. Sequestration rates however, must be assessed in terms of their overall global warming potential (GWP) which must also consider GHG emissions. The objectives of this study were to (1) compare carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) emissions from two types of hedgerows and adjacent annual agricultural production fields, and 2) better understand how climate, soil properties and plant species configurations affect hedgerow GHG emissions. At eight study sites in the lower Fraser River delta of British Columbia, we measured emissions from soil in both planted (P-Hedgerow) and remnant hedgerows (R-Hedgerow), as well as in adjacent annual crop production fields over 1 year using a closed-static chamber method. CO2 emissions were 59 % higher in P-Hedgerow than R-Hedgerow, yet there were no significant differences of relative emissions of CH4 and N2O. The environmental variables that explained the variation in emissions differed for the three GHGs. CO2 emissions were significantly correlated with soil temperature. CH4 and N2O and emissions were marginally significantly correlated with soil organic carbon (SOC) and soil water-filled pore space (WFPS), respectively. Emissions were not significantly correlated with hedgerow plant species diversity. While hedgerows sequester carbon in their woody biomass, we demonstrated that it is critical to measure hedgerow emissions to accurately ascertain their overall GHG mitigation potential. Our results show that there are no CO2e emission differences between the management options that plant new diverse hedgerows or conserve existing hedgerows.
... Foram A floresta nativa apresentou os menores valores de biomassa e estoques de carbono em relação aos sistemas com monoculturas e um número intermediário de indivíduos por hectare. De acordo com Catovsky et al. (2002), o potencial de carbono na biomassa aumenta com a diversidade de espécies em um determinado ecossistema, em função da otimização da fotossíntese das diferentes espécies que o compõem. Sausen et al. (2013) apontam que em florestas nativas a ocorrência de determinadas espécies detentoras de grande porte é o principal fator que promove incremento em biomassa e nos estoques de carbono e que algumas espécies contribuem de maneira mais acentuada para os estoques de carbono, sendo o aumento do estoque proporcional ao volume de madeira. ...
Forests have a key role in carbon sequestration due to its ability
to remove carbon dioxide from the atmosphere and stores it in plant biomass.
To achieve the full potential of carbon sequestration, one needs accurate
methods to assess its dynamics and storage in different forest systems. This
study evaluated the efficiency of three systems related to forest biomass and
carbon stocks. We analyzed Eucalyptus grandis and Pinus elliottii plantations
as well as an old-growth native forest remnant. We collected allometric data
and stem samples to determine basic wood density, biomass and carbon stocks
estimates. For the sampled species, basic wood density ranged from 0.31 g
cm-3 to 0.81 g cm-3. Biomass and carbon stocks were higher in Eucalyptus
grandis (344.58 Mg ha-1; 172.87 Mg ha-1) than in Pinus elliottii (215.75 Mg
ha-1; 107.87 Mg ha-1) and on the forest remnant (168.20 Mg ha-1; 84.10 Mg
ha-1). At the native forest, species with higher accumulated carbon were Luehea
divaricata (16.92 Mg ha-1), Nectandra megapotamica (10.10 Mg ha-1),
Lonchocarpus campestris (9.54 Mg ha-1) Matayba elaeagnoides (8.93 Mg
ha-1) and Jacaranda micrantha (7.00 Mg ha-1).
... Moreover, plant function diversity and tree species richness positively corelated to biomass carbon stock of forest (Guo and Ren 2014). More diverse ecosystems might accumulate more carbon as a result of increased photosynthetic inputs (Catovsky et al. 2002). The translation of tree species composition (from coniferous to broadleaved tree species) and the enhance of plant diversity resulted in the increase of vegetation biomass carbon stocks across the forest succession. ...
Background and aims Forest ecosystems represent an important carbon sink. A few studies have reported carbon stocks in a forest chronosequence, the carbon stock pattern variation and proportion of each compartment remain poorly understood. The objectives of this study were to quantify carbon stocks of each compartment of forest ecosystem and access their contribution to forest carbon stocks with forest succession.
Methods Totally, 32 plots (20 m × 50 m) in different stages of forest succession were investigated, including 11 replicates for Masson pine forest at the early stage, 9 for pine-broadleaved mixed forest at the middle stage, and 12 for evergreen broadleaved forest at succession climax, to quantify carbon stocks in trees, shrubs, herbaceous plants, litter and coarse woody debris (CWD), and soil.
Results The total ecosystem carbon stocks ranged from 193 to 257 Mg ha-1, of which vegetation carbon stocks ranged from 94 to 129 Mg ha-1. Tree biomass carbon stocks increased but shrub biomass carbon stocks decreased during forest succession. The increment of tree biomass carbon stocks was far more than that of shrub, resulting in the increases of vegetation carbon stocks during forest succession. Debris carbon stocks ranged from 4.2 to 5.6 Mg ha-1, with no significant variation across the forest chronosequence. The soil carbon stocks (top 100 cm) ranged from 96 to 132 Mg ha-1. Soil carbon stocks increased significantly during the forest chronosequence, of which soil carbon accumulation occured mainly in the topsoil (0-30 cm). There were no significant differences among the proportions of forest ecosystem carbon stocks in the chronosequence. The averages of proportions of vegetation biomass, debris and soil carbon were 46.7%, 2.1% and 51.2 %, respectively.
Conclusions Our results present robust evidence for the increasing carbon sequestration across forest succession chronosequence.. Furthermore, tree growth and carbon accumulation in topsoil layer contribute equivalently to carbon sequestration during forest succession in subtropical China.
... A number of carbon budget measures are used to assess the carbon-regulating service of ecosystems. Net primary productivity (NPP) is the rate at which plants incorporate atmospheric CO 2 through photosynthesis, which is the amount of carbon retained within plant biomass (Catovsky et al. 2002). It can also be described as the total amount of carbon fixed by the vegetation (gross primary productivity [GPP]) minus plant respiration and losses to the soil (fine root turnover, exudation) and heterotrophs. ...
... As capoeiras e os SAFs apresentaram maior diversidade total de espécies que os sistemas agrícolas e as pastagens (Figura 1). Catovsky et al. (2002) afirmam que quanto maior a diversidade de espécies em um determinado ecossistema, maior será o potencial de estoque de carbono na biomassa, em função da otimização da fotossíntese das diferentes espécies que compõem o ecossistema. Desta forma, os SAFs multiestrata, por sua diversidade horizontal e vertical, tendem a proporcionar estoques de carbono similares a ambientes naturalmente biodiversos. ...
Foi avaliado o estoque de carbono no solo, serapilheira, biomassa arbórea e biomassa herbácea de SAFs multiestratos, em comparação a capoeiras em diferentes estágios de regeneração, sistemas agrícolas convencionais e pastagem, todos na região do Alto Vale do Ribeira, SP. Nos Neossolos e Cambissolos, com baixos teores de carbono orgânico e similaridade dos valores de densidade aparente, as capoeiras contribuíram com 115,78 Mg ha-1 de carbono total estocado, seguidas dos SAFs (75,37 Mg ha-1), das áreas agrícolas (47,07 Mg ha-1) e das pastagens (36,01 Mg ha-1). Apesar do grande potencial de sequestro de carbono dos SAFs, há necessidade de melhoria em suas práticas silviculturais.
doi: 10.4336/2011.pfb.31.66.143
Above and belowground linkages are responsible for some of the most important ecosystem processes in unmanaged terrestrial systems including net primary production, decomposition, and carbon sequestration. Global change biology is currently altering above and belowground interactions, reducing ecosystem services provided by natural systems. Less is known regarding how above and belowground linkages impact climate resilience, especially in intentionally managed cropping systems. Waterlogged or flooded conditions will continue to rise across the Midwest, United States due to climate change. The objective of this paper is to explore what is currently known regarding above and belowground linkages and how they impact biological, biochemical, and physiological processes in systems experiencing waterlogged conditions. We also identify key above and belowground processes that are critical for climate resilience in midwestern cropping systems by exploring various interactions that occur within unmanaged landscapes. Above and belowground interactions that support plant growth and development, foster multi-trophic level interactions, and stimulate balanced nutrient cycling are critical for crops experiencing waterlogged conditions. Moreover, incorporating ecological principles such as increasing plant diversity by incorporating crop rotations and adaptive management via delayed planting dates and adjustments in nutrient management will be critical for fostering climate resilience in row-crop agriculture moving forward.
Grazing is very common in the grassland ecosystem, and it has a significant impact on the C stocks and cycle. One of the most important drivers of soil C stocks is functional diversity. However, limited studies have attempted to explore the effects of functional diversity on soil C stocks associated with grazing disturbance. This study was carried out in Hulunbeier grassland, Inner Mongolia, and four grazing intensities (no grazing (NG), light grazing (LG), moderate grazing (MG), and heavy grazing (HG)) were identified. The plant functional traits and important soil properties under different grazing intensities were measured. Functional identity and diversity were calculated based on the measured functional traits. The impacts of functional identity and diversity on soil organic carbon stocks (SOCstocks) were analyzed using a multi-model inference (MMI) approach. Our study showed that the functional diversity effect on soil C stocks varies depending on grazing intensity. We identified that functional richness has a significant impact on SOCstocks in NG. The community weighted mean of leaf area became the best predictor of SOCstocks in LG. As grazing intensified, functional divergence best explained SOCstocks in moderate and heavy grazing sites, and their relationship was positive. The major outcomes of this research could shed light on the mechanics of soil carbon storage.
Soil microbial communities and plants are intimately associated and each can regulate the growth and specific composition of the other through relationships such as competition and symbiosis. Such links between the above and belowground components of soil ecosystems are important as they determine the functioning of key ecosystem processes, including decomposition and nutrient cycling. In the present study, we used structural equation models to investigate the direct and indirect effects of plant community properties (richness, evenness and net primary productivity) and of soil nutrient pools (C, N and P) on the biomass of rhizosphere and non-rhizosphere bacteria and fungi. The biomass of rhizosphere and non-rhizosphere bacteria and fungi was mainly determined by the organic matter content. More importantly, nutrient pools were not modulated by plant communities and we did not find any evidence of a link between aboveground and belowground components of soil systems in this respect. The findings indicate that aboveground and belowground components of the soil system are not directly linked and that any potential relationships will be mediated by the effects of aboveground components in nutrient pools.
In order to understand the effects of shade tree species on the carbon storage of differ鄄
ent tree鄄tea agroforestry systems, three plots with a size of 20 m 伊 25 m were established in each
of five different tea gardens, i. e. , a monoculture tea garden and four tea gardens with one, two,
four, and six shade tree species, respectively in Menghai County, Xishuangbanna. Biomass re鄄
gression models were constructed by using the DBH of shade trees and the BD (basal diameter)
of tea shrubs, soil samples were taken from five layers (0 -20, 20 -40, 40 -60, 60 -80, and
80-100 cm) in each plot, and the carbon storage was then estimated, based on the carbon con鄄
tents in different organs of trees and tea shrubs and in soils. The total carbon storage of monocul鄄
ture tea garden (223. 442 t· hm-2) was 22. 701 and 3. 871 t· hm-2 lower than that of the Cin鄄
namomum pathenoxylum鄄tea and Cinnamomum pathenoxylum+Cunninghamia lanceolata鄄tea gar鄄
dens, but 10. 828 and 5. 717 t· hm-2 higher than that of the tea gardens with four and six shade
tree species, respectively. Soil carbon storage accounted for 91. 8% -96. 0% of the total carbon
storage, being the lowest in the tea garden with four shade tree species. The carbon storage of
plants only occupied 4. 0% -8. 2% of the total carbon storage, and increased from the tea gar鄄
dens with one to four shade tree species but decreased sharply in the tea garden with six shade
tree species. Our results suggested that the tree鄄tea agroforestry systems in Xishuangbanna had a
strong capacity of carbon sequestration.
Positive relationships between plant species diversity and carbon attributes have been observed in grasslands, but synthesis studies of how plant diversity affects the carbon balance of grasslands and how the response ratio changes over time both remain limited. By conducting a global meta-analysis with 811 paired observations of plant mixtures and monocultures from 83 studies in natural and manipulated grasslands, we investigated the impacts of plant diversity on six carbon attributes, its interaction with experimental duration, and the changes in carbon balance under different plant diversity loss scenarios in the future. We found that the aboveground biomass (AGB), belowground biomass (BGB), total biomass (TB), soil organic carbon (SOC), soil respiration (Rs), and heterotrophic respiration (Rh) significantly increased in the plant mixtures, and the response ratio for all carbon attributes increased logarithmically with species richness. We also found that the response ratio for all carbon attributes except Rs increased linearly with experimental duration. The increase in response ratio of AGB, BGB, TB, and SOC with species richness was more pronounced with the long-term experimental duration. Importantly, our results showed that the declines in carbon sequestration will be exacerbated by different plant diversity loss scenarios in the future. Our meta-analysis revealed that plant diversity loss has ubiquitous negative impacts on multiple carbon attributes in grasslands, underlined the interactive effects of plant diversity loss and experimental duration on carbon attributes, and suggested that the reduction of carbon storage in grasslands following biodiversity loss will be greater in the future.
Este trabajo analiza el banco de semillas en diferentes sustratos (hojarasca y suelo) para conocer el efecto de la temporalidad y la orientación de la ladera sobre la abundancia y composición del banco y de la vegetación establecida en un bosque templado en la Ciudad de México. ¿Qué factores abióticos determinan la germinación de nuevos individuos de distintos grupos funcionales?, ¿De qué manera esta información contribuye a la planeación de programas de conservación y restauración? Este estudio se realizó en 30 parcelas establecidas en el bosque (ladera norte y sur) durante las dos temporadas del año. Bosque templado de Quercus rugosa (L.) en la cuenca del río Magdalena, Cd. de México. Mediante una clasificación TWINSPAN se determinaron nueve grupos funcionales de banco de semillas y vegetación establecida. Mediante un análisis de Permutación de Respuesta Múltiple (MRPP) y un Análisis de Correspondencia Canónica (CCA) se determinó el efecto temporal y espacialmente sobre la abundancia y riqueza de los grupos funcionales. Se encontró una alta similitud dentro de cada grupo funcional y una alta disimilitud entre ellos. El Análisis de Varianza de Permutación Multivariado (PERMANOVA) mostró un efecto significativo de la temporada y la orientación sobre la identificación de los grupos funcionales. En términos de conservación la presencia de especies características y nativas implica que hay una alta resiliencia, sin embargo, la presencia de especies introducidas indica cambios en la composición del sistema, lo cual compromete el potencial de la regeneración natural.
Palabras clave: Germinación, hojarasca, reclutamiento, sustratos, temporalidad, vegetación establecida.
Abstract
This research analyzes the seed bank of different substrates (litter and soil) and the standing vegetation to know the effects of the season and slope orientation on their abundance and composition in a temperate forest in Mexico City. Which abiotic factors determine the germination of new individuals of different functional groups? how this information can contribute in the planning of conservation and restoration programs?Which environmental factors determine germination and the recruiting of individuals? And how this knowledge could be considered in conservation programs? This research was carried out in 30 plots established in the forest (North and South slopes) during both year seasons. Temperate forest of Quercus rugosa (L.) in the Magdalena river Basin, Mexico City. Through a TWINSPAN classification nine functional groups were determined in the seed bank and the standing vegetation. Through a Multiple Response Permutation Analysis (MRPP) and a Canonical Correspondence Analysis (CCA) the environmental effect was determined, seasonally and spatially on the abundance and richness of the functional groups. A high similarity inside each functional group and a high dissimilarity between them were found. The Multivariate Permutation Variance Analysis (PERMANOVA) showed a significant effect of the season and of the slope orientation on the identification of the functional groups. In terms of conservation the presence of characteristic and native species implies a high resilience, however the presence of introduced species indicates changes in the system composition, which jeopardizes the natural regeneration potential.
Antecedentes:
Este trabajo analiza el banco de semillas en diferentes sustratos (hojarasca y suelo) para conocer el efecto de la temporalidad y la orientación de la ladera sobre la abundancia y composición del banco y de la vegetación establecida en un bosque templado en la Ciudad de México.
Preguntas:
¿Qué factores abióticos determinan la germinación de nuevos individuos de distintos grupos funcionales?, ¿De qué manera esta información contribuye a la planeación de programas de conservación y restauración?
Descripción de datos:
Este estudio se realizó en 30 parcelas establecidas en el bosque (ladera norte y sur) durante las dos temporadas del año.
Sitio de estudio:
Bosque templado de Quercus rugosa (L.) en la cuenca del río Magdalena, Cd. de México.
Métodos:
Mediante una clasificación TWINSPAN se determinaron nueve grupos funcionales de banco de semillas y vegetación establecida. Mediante un análisis de Permutación de Respuesta Múltiple (MRPP) y un Análisis de Correspondencia Canónica (CCA) se determinó el efecto temporal y espacialmente sobre la abundancia y riqueza de los grupos funcionales.
Resultados:
Se encontró una alta similitud dentro de cada grupo funcional y una alta disimilitud entre ellos. El Análisis de Varianza de Permutación Multivariado (PERMANOVA) mostró un efecto significativo de la temporada y la orientación sobre la identificación de los grupos funcionales.
Conclusiones:
En términos de conservación la presencia de especies características y nativas implica que hay una alta resiliencia, sin embargo, la presencia de especies introducidas indica cambios en la composición del sistema, lo cual compromete el potencial de la regeneración natural.
Fine roots play a key role in the global carbon (C) cycle because much of the C accumulating in soil is the result of fine root production and turnover. Here we explore the effect of plant community composition and diversity on fine root production in surface soils and plant biomass allocation to fine roots in six perennial cropping systems differing in composition and diversity planted as biofuel feedstocks. The six systems were established in 2008 at both a high and a moderate fertility site located in the upper Midwest, USA and included: switchgrass (Panicum virgatum), miscanthus (Miscanthus  giganteus), hybrid poplar (Populus nigra  P. maximowiczii 'NM6), native grasses (a five-species assemblage of Andropogon gerardii, Elymus canadensis, P. virgatum, Schizachrium scoparium, and Sorghastrum nutans), an early successional system, and a restored prairie with 25 sown grass, legume, and forb species. For three years (2011e2013) at both sites ingrowth cores were deployed each spring; half were extracted at mid-season and the rest in late fall. Native grasses and restored prairie systems produced 31e77% more fine roots by mid-season compared to the other cropping systems at both sites. Miscanthus and hybrid poplars tended to have the lowest fine root production. The polyculture cropping systems allocated 39 e94% more energy to the production of fine roots, with the exception of switchgrass at the low fertility site. Findings demonstrate a greater potential for diverse biofuel cropping systems to allocate C belowground to fine roots as compared to monocultures, with potential implications for soil C sequestration.
Conservation methods often are focused on preserving the biodiversity of a particular landscape or ecosystem. Scientists frequently employ species richness as an indicator of biodiversity. However, species richness data are problematic when attempts are made to enumerate microfungi, particularly those from the soil. Many soil fungi fail to sporulate, making identification difficult. Other means of assessing the importance of fungi to ecosystem preservation must be developed. Otherwise, microfungi might be overlooked in discussions of ecosystem management and conservation issues. Herein, we have described a procedure (Soil FungiLog) and analytical techniques that will let investigators examine the functional role that soil fungi play in providing structure and stability to ecosystems. Ecosystem function in many cases might be more important than species diversity in gaining an understanding of ecosystem dynamics. Functional attributes are critical for maintaining ecosystem structure and stability. The preservation of the functions associated with the extant biota, particularly from soil microbes, might be just as important as species diversity in the conservation of ecosystems and biodiversity. The Soil FungiLog procedure was used to assess functional diversity of soil fungi in a Georgia forest disturbed by human activity and along an elevational gradient in the Chihuahuan Desert. Sites within each location were separated on the basis of fungal carbon substrate utilization profiles. These profiles were analyzed to provide information regarding the functional diversity of soil fungal assemblages at each site. The effects of disturbance and elevation were evaluated with respect to soil fungal functional diversity.
Iran is categorized under Low Forest Cover Countries and the Nour Forest Park is the largest coastal plain forest in the country. As forest soils contain higher carbon than plant biomass and play a key role in the global carbon cycle, this study aimed to assess highly accurately usable models for monitoring soil organic carbon (SOC) based on plant- species diversity in the forest. For measuring plant-species diversity indices and taking soil samples at two depths (0–20 and 20–40 cm), a total of 75 plots based on a randomized complete block (RCB) design which included three naturally different stand types were outlined in the forest. Traditional models based on multiple linear regression and curve estimation regression analyses, and artificial neural network (ANN) type of multi-layer perception on the basis of back-propagation training algorithm were used for predicting the SOC. According to the Pearson's correlation, the traditional functions and ANN models including Abundance and evenness (J′) of herbs layer, and dominance (D) of trees layer, Abundance andJ′of herbs layer in turns were developed for predicting the SOC in the soil top and subsoil layer. The findings showed that the power-law models based on validation parameters among the traditional models were the best predictors for SOC in the different soil layers. Designing the topology of each model in the ANN on the basis of training algorithm and testing data set indicated that the best architectures in the optimum models in turns were composed of one hidden layer with 15 neurons including tangent sigmoid function (A3) for predicting the SOC in the soil organic layer, and two hidden layers with 35 neurons in each layer including the same function (A6) for predicting the subsoil (mineral) layer. Also, the optimum models in the ANN including A3 (R² = 0.87 , RMSE % = 8.17) and A6 (R² = 0.93 , RMSE % = 3.73), in comparison with the traditional models, predicted the SOC with a higher accuracy. Since the optimum models in the ANN predicted the response values with the highest accuracy and without major concerns for statistical issues and uncertainty, the ANN technique is suggested for monitoring SOC in the forest.
Extreme exploitation and maltreatment of land in a number of countries had devastating impacts on terrestrial ecosystems (i.e., loss of biodiversity of flora and fauna). Biodiversity became a political topic (UNEP, and Convention on Biological Diversity (CBD) of the United Nations) decades ago and was recently linked to agricultural practices in general (OECD, FAO). A survey of reports on "sustainable land use", "soil fertility", and "soil biodiversity" which are published by such organizations leave the impression that soil fertility is controlled by soil biodiversity. In essence this would mean that a low soil fertility occurs together with a decrease in soil biodiversity. Here is the point where assumptions and scientific evidence are far apart with respect to below-ground biodiversity. Because the current discussion propagates soil biodiversity as a soil quality indicator, it seems necessary to question this approach with respect to microbial biodiversity of soils. Biological soil functions such as the maintenance of soil fertility are based on the concerted action of soil organisms such as soil microflora and soil fauna. For both biological entities no specific soil functions can be assigned to species diversity per se. Since organic matter turnover and nutrient turnover are mainly dependent on the activity of the soil microbial biomass (bacteria and fungi), the present paper concentrates on this biological soil fraction. An attempt will be made to give an overview of the scientific background of soil microbial biodiversity. Interdependencies between the abiotic and biotic components will be described, together with the relationship between above-ground and below-ground biodiversity.
Forests contain 70–80 percent of terrestrial carbon (C) and represent a global C sink, despite of continued deforestation. On the other hand, forests and land-use change (LUC) account for the largest uncertainties within the global C balance. The future role of forests is even more uncertain within the context of global change. The question if forests will shift from C sinks to sources is fundamental for conservation and management. We aim to synthesize current knowledge on the
role of the major forest biomes in the global C cycle. Furthermore, we evaluate management options, based on their potential to maximize greenhouse gas (GHG) mitigation and other benefits from forest ecosystems. Whereas boreal and temperate forests currently act as net sinks, there is a potential for increased insect outbreaks, fires, and droughts. Pressure from infrastructure development and the demand for biomass fuels is increasing. Tropical forests account for the largest gross C sink, but face deforestation and degradation. The future role of tropical forests depends mostly on LUC dynamics. Uncertainties persist about deforestation rates and impacts from global change. It is clear, however, that changes in the C balance of tropical forests will affect atmospheric CO2 levels on a global scale. In managed temperate and boreal forests, aboveground carbon (AGC) can be maximized by optimizing rotation cycles in even-aged stands. Mixed-species stands may increase productivity and resilience to disturbances. Research is needed on the impacts of silvicultural activities on soil organic carbon (SOC). In the tropics, reforestation and deforestation avoidance are the most important GHG mitigation pathways. Lessons learnt from REDD (reduced emissions from deforestation and forest degradation) pilot projects may help to establish GHG mitigation strategies in the future. The majority of timber harvest in the tropics is unsustainable and could be improved by extending rotation cycles, reduced impact
logging, and long-term management planning. International support is needed to ensure capacity building and strong institutions, and to create incentives for global markets. The extension of planted forests is growing worldwide. Plantations sequester important amounts of C, although afforestation may initially lead to SOC losses, and AGC storage over multiple rotation cycles is low, compared to natural forests. Conservation of old-growth forests is the most effective way to secure C storage.
Reducing atmospheric carbon dioxide (CO2) concentration through enhanced terrestrial carbon storage may help slow or reverse the rate of global climate change. As a result, Federal land management agencies, such as the U.S. Department of Agriculture Forest Service and U.S. Department of the Interior Bureau of Land Management, are implementing management policies to increase carbon storage. However, information on how projected southwestern climate changes might affect the balance between CO2 uptake and loss on semiarid rangelands is not easily accessible to land managers. We summarize studies that focus on key components of carbon exchange, including photosynthesis, soil respiration, and plant productivity, across the warm deserts of North America to determine if common trends exist that can be utilized in management. We also provide an overview of how management practices can influence carbon sequestration in this region and discuss the U.S. Department of Agriculture Forest Service Climate Change Scorecard. Since desertification is projected to increase in the future, management strategies that increase carbon sequestration or decrease carbon loss are especially important. This requires managers to thoughtfully consider management practices that do not impede sequestration during critical times. For a popular version of the GTR see Rangelands February 2014.
sici?sici=0012-9615%28199212%2962%3A4%3C569%3AMAFIAE%3E2.0.CO%3B2-Z Ecological Monographs is currently published by The Ecological Society of America.'s Terms and Conditions of Use provides, in part, that unless you have obtained prior permission, you may not download an entire issue of a journal or multiple copies of articles, and you may use content in the JSTOR archive only for your personal, non-commercial use. Each copy of any part of a JSTOR transmission must contain the same copyright notice that appears on the screen or printed page of such transmission. JSTOR is an independent not-for-profit organization dedicated to and preserving a digital archive of scholarly journals. For more information regarding JSTOR, please contact support@jstor.org.
Basic trophic-dynamic models using prey-dependent prey-predator interactions typically predict (1) that the limiting factors, resources and predation, should alternate at adjacent trophic levels, and (2) that only biomasses at resource limited levels should increase when the productivity of a system is increased. However, experimental studies on aquatic systems have shown that biomasses tend to respond to increased productivity at all trophic levels. To test the predictions in a terrestrial environment, we performed an experiment with a soil food web. We established three food webs with one, two, or three trophic levels in microcosms containing an initially sterilized mixture of leaf litter and raw humus, and increased the productivity with additional glucose in half of the replicates of each food web. The first trophic level contained 22 species of bacteria and fungi, the second level a bacterivorous nematode (Caenorhabditis elegans) and a fungivorous nematode (Aphelenchoides sp.), and the third level a predatory nematode (Prionchulus punctatus). We sampled the microcosms destructively four times during the 22-week experiment to estimate the trophic-level biomasses and soil NH4+-N concentration. Evolution of CO2 was measured to estimate microbial productivity. Microbial productivity was greater and the amount of NH4+-N lower in the communities provided with additional energy. The presence of microbivores also resulted in greater microbial productivity than in the pure microbial community. The biomass of microbes and microbivores increased when provided with supplementary energy independently of the number of trophic levels in the food web, while the biomass of the predatory nematode did not significantly respond to additional energy. The predatory and the bacterial feeding nematodes limited the biomass of their resources, whereas the fungal biomass was unaffected by the fungivore. The results infer that the biomasses at the first and second trophic level were simultaneously limited by resources and predation, which contradicts basic prey-dependent models. Prey refuges provided by soil structure may explain the inability of predators to control their preys as effectively as predicted by these models. Moreover. the results suggest that the nature of trophic interactions may differ at the bottom and top of soil food webs, and between the fungal and bacterial channels.
Annual C inputs from plant production in terrestrial ecosystems only meet the maintenance energy requirements of soil microorganisms, allowing for little or no net annual increase in their biomass. Because microbial growth within soil is limited by C availability, we reasoned that plant production should, in part, control the biomass of soil microorganisms. We also reasoned that soil texture should further modify the influence of plant production on soil C availability because fine-textured soils typically support more microbial biomass than coarse- textured soils. To test these ideas, we quantified the relationship between aboveground net primary production (ANPP) and soil microbial biomass in late-successi onal ecosystems dis- tributed along a continent-wide gradient in North America. We also measured labile pools of C and N within the soil because they represent potential substrate for microbial activity. Eco- systems ranged from a Douglas-fir forest in the western United States to the grasslands of the mid-continent to the hardwood forests in the eastern U.S. Estimates of ANPP obtained from the literature ranged from 82 to 1460 g-m~ 2 -yr~'. Microbial biomass C and N were estimated by the fumigation-incubation technique. Labile soil pools of C and N and first-order rate constants for microbial respiration and net N mineralization were estimated using a long-term (32 wk) laboratory incubation. Regression analyses were used to relate ANPP and soil texture with microbial biomass and labile soil C and N pools. Microbial biomass carbon ranged from 2 g/m2 in the desert grassland to 134 g/m2 in the tallgrass prairie; microbial N displayed a similar trend among ecosystems. Labile C pools, derived from a first-order rate equation, ranged from 115 g/m2 in the desert grassland to 491 g/m2 in the southern hardwood forest. First-order rate constants for microbial respiration (fc) fell within a narrow range of values (0.180 to 0.357 wk~'), suggesting that labile C pools were chemically similar among this diverse set of ecosystems. Potential net N mineralization rates over the 32- wk incubation were linear in most ecosystems with first-order responses only in the alpine tundra, tallgrass prairie, and forests. Microbial biomass C displayed a positive, linear relationship with ANPP (r2 = 0.51), but was not significantly related to soil texture. Labile C also was linearly related to ANPP (r2 = 0.32) and to soil texture (r2 = 0.33). Results indicate that microbial biomass and labile organic matter pools change predictably across broad gradients of ANPP, supporting the idea that microbial growth in soil is constrained by C availability.
The consequences of permanent loss of species or species groups from plant communities are poorly understood, although there is increasing evidence that individual species effects are important in modifying ecosystem properties. We conducted a field experiment in a New Zealand perennial grassland ecosystem, creating artificial vegetation gaps and imposing manipulation treatments on the reestablishing vegetation. Treatments consisted of continual removal of different subsets or “functional groups” of the flora. We monitored vegetation and soil biotic and chemical properties over a 3-yr period. Plant competitive effects were clear: removal of the C3 grass Lolium perenne L. enhanced vegetative cover, biomass, and species richness of both the C4 grass and dicotyledonous weed functional groups and had either positive or negative effects on the legume Trifolium repens L., depending on season. Treatments significantly affected total plant cover and biomass; in particular, C4 grass removal reduced total plant biomass in summer, because no other species had appropriate phenology. Removal of C3 grasses reduced total root biomass and drastically enhanced overall shoot-to-root biomass ratios. Aboveground net primary productivity (NPP) was not strongly affected by any treatment, indicating strong compensatory effects between different functional components of the flora. Removing all plants often negatively affected three further trophic levels of the decomposer functional food web: microflora, microbe-feeding nematodes, and predaceous nematodes. However, as long as plants were present, we did not find strong effects of removal treatments, NPP, or plant biomass on these trophic groupings, which instead were most closely related to spatial variation in soil chemical properties across all trophic levels, soil N in particular. Larger decomposer organisms, i.e., Collembola and earthworms, were unresponsive to any factor other than removal of all plants, which reduced their populations. We also considered five functional components of the soil biota at finer taxonomic levels: three decomposer components (microflora, microbe-feeding nematodes, predaceous nematodes) and two herbivore groups (nematodes and arthropods). Taxa within these five groups responded to removal treatments, indicating that plant community composition has multitrophic effects at higher levels of taxonomic resolution. The principal ordination axes summarizing community-level data for different trophic groups in the soil food web were related to each other in several instances, but the plant ordination axes were only significantly related to those of the soil microfloral community. There were time lag effects, with ordination axes of soil-associated herbivorous arthropods and microbial-feeding nematodes being related to ordination axes representing plant community structure at earlier measurement dates. Taxonomic diversity of some soil organism groups was linked to plant removals or to plant diversity. For herbivorous arthropods, removal of C4 grasses enhanced diversity; there were negative correlations between plant and arthropod diversity, presumably because of negative influences of C4 species in the most diverse treatments. There was evidence of lag relationships between diversity of plants and that of the three decomposer groups, indicating multitrophic effects of altering plant diversity. Relatively small effects of plant removal on the decomposer food web were also apparent in soil processes regulated by this food web. Decomposition rates of substrates added to soils showed no relationship with treatment, and rates of CO2 evolution from the soil were only adversely affected when all plants were removed. Few plant functional-group effects on soil nutrient dynamics were identified. Although some treatments affected temporal variability (and thus stability) of soil biotic properties (particularly CO2 release) throughout the experiment, there was no evidence of destabilizing effects of plant removals. Our data provide evidence that permanent exclusion of plant species from the species pool can have important consequences for overall vegetation composition in addition to the direct effects of vegetation removal, and various potential effects on both the above- and belowground subsystems. The nature of many of these effects is driven by which plant species are lost from the system, which depends on the various attributes or traits of these species.
The annual net uptake of CO2 by a deciduous forest in New England varied from 1.4 to 2.8 metric tons of carbon per hectare between 1991 and 1995. Carbon
sequestration was higher than average in 1991 because of increased photosynthesis and in 1995 because of decreased respiration.
Interannual shifts in photosynthesis were associated with the timing of leaf expansion and senescence. Shifts in annual respiration
were associated with anomalies in soil temperature, deep snow in winter, and drought in summer. If this ecosystem is typical
of northern biomes, interannual climate variations on seasonal time scales may modify annual CO2 exchange in the Northern Hemisphere by 1 gigaton of carbon or more each year.
Knowledge of carbon exchange between the atmosphere, land and the oceans is important, given that the terrestrial and marine environments are currently absorbing about half of the carbon dioxide that is emitted by fossil-fuel combustion. This carbon uptake is therefore limiting the extent of atmospheric and climatic change, but its long-term nature remains uncertain. Here we provide an overview of the current state of knowledge of global and regional patterns of carbon exchange by terrestrial ecosystems. Atmospheric carbon dioxide and oxygen data confirm that the terrestrial biosphere was largely neutral with respect to net carbon exchange during the 1980s, but became a net carbon sink in the 1990s. This recent sink can be largely attributed to northern extratropical areas, and is roughly split between North America and Eurasia. Tropical land areas, however, were approximately in balance with respect to carbon exchange, implying a carbon sink that offset emissions due to tropical deforestation. The evolution of the terrestrial carbon sink is largely the result of changes in land use over time, such as regrowth on abandoned agricultural land and fire prevention, in addition to responses to environmental changes, such as longer growing seasons, and fertilization by carbon dioxide and nitrogen. Nevertheless, there remain considerable uncertainties as to the magnitude of the sink in different regions and the contribution of different processes.
We assess the evidence for correlation between aboveground and belowground diversity and conclude that a variety of mechanisms could lead to positive, negative, or no relationship – depending on the strength and type of interactions among species.
At eight European field sites, the impact of loss of plant diversity on primary productivity was simulated by synthesizing
grassland communities with different numbers of plant species. Results differed in detail at each location, but there was
an overall log-linear reduction of average aboveground biomass with loss of species. For a given number of species, communities
with fewer functional groups were less productive. These diversity effects occurred along with differences associated with
species composition and geographic location. Niche complementarity and positive species interactions appear to play a role in generating diversity-productivity relationships
within sites in addition to sampling from the species pool.
The loss of plant species from terrestrial ecosystems may cause changes in soil decomposer communities and in decomposition of organic material with potential further consequences for other ecosystem processes. This was tested in experimental communities of 1, 2, 4, 8, 32 plant species and of 1, 2 or 3 functional groups (grasses, legumes and non-leguminous forbs). As plant species richness was reduced from the highest species richness to monocultures, mean aboveground plant biomass decreased by 150%, but microbial biomass (measured by substrate induced respiration) decreased by only 15% (P = 0.05). Irrespective of plant species richness, the absence of legumes (across diversity levels) caused microbial biomass to decrease by 15% (P = 0.02). No effect of plant species richness or composition was detected on the microbial metabolic quotient (qCO 2) and no plant species richness effect was found on feeding activity of the mesofauna (assessed with a bait-lamina-test). Decomposition of cellulose and birchwood sticks was also not affected by plant species richness, but when legumes were absent, cellulose samples were decomposed more slowly (16% in 1996, 27% in 1997, P = 0.006). A significant decrease in earthworm population density of 63% and in total earthworm biomass by 84% was the single most prominent response to the reduction of plant species richness, largely due to a 50% reduction in biomass of the dominant 'anecic' earthworms. Voles (Arvicola terrestris L.) also had a clear preference for high-diversity plots. Soil moisture during the growing season was unaffected by plant species richness or the number of functional groups present. In contrast, soil temperature was 2 K higher in monocultures compared with the most diverse mixtures on a bright day at peak season. We conclude that the lower abundance and activity of decomposers with reduced plant species richness was related to altered substrate quantity, a signal which is not reflected in rates of decomposition of standard test material. The presence of nitrogen fixers seemed to be the most important component of the plant diversity manipulation for soil heterotrophs. The reduction in plant biomass due to the simulated loss of plant species had more pronounced effects on voles and earthworms than on microbes, suggesting that higher trophic levels are more strongly affected than lower trophic levels.
Summary1 Utilization of carbon sources by culturable soil bacteria can be assessed with BIOLOG microtiter plates (contain 31 C sources). We used this technique to investigate bacterial community structure at various levels of plant diversity. Plant diversity levels were replicated and we investigated the influence of three plant functional groups, grasses, legumes and non-leguminous herbs, as well as the influence of individual plant species.2 Catabolic activity and catabolic diversity of culturable soil bacteria were used to estimate their density (abundance) and functional diversity, respectively. Both increased linearly with the logarithm of plant species number and with the number of plant functional groups in experimental grassland ecosystems. These effects may have been caused by an increased diversity and quantity of material and energy flows to the soil. They may also have been mediated by increased diversity of soil microhabitats via a stimulation of the soil fauna.3 The presence of particular plant species or functional groups in the different experimental communities stimulated the activity and functional diversity of the culturable soil bacteria in addition to their contribution via plant diversity. The legume Trifolium repens had the strongest effect and may be regarded as a keystone species with regard to plant–microbial interactions in the systems studied.
The significance of biodiversity to biogeochemical cycling is viewed most directly through the specific biogeochemical transformations that organisms perform. Although functional diversity in soils can be great, it is exceeded to a high degree by the richness of soil species. It is generally inferred from this richness that soil systems have a high level of functional redundancy. As such, indices of species richness probably contribute little to understanding the functioning of soil ecosystems. Another approach stresses the value of identifying “keystone” organisms, that is those that play an exceptionally important role in determining the structure and function of ecosystems. Both views tend to ignore the importance of biodiversity in maintaining the numerous and complex interactions among organisms in soils and their contributions to biogeochemical cycling. We describe some of those interactions and their importance to ecosystem function.
Soil organisms alter the physical, chemical and biological properties of soils in innumerable ways. The composition and structure of biotic communities at one hierarchical level can influence the spatial heterogeneity of resource and refuge patches at other hierarchical levels. This spatial heterogeneity is supported by a number of biologically relevant spheres of influence that include the detritusphere, the drilosphere, the porosphere, the aggregatusphere and the rhizosphere. Each has fairly distinct properties that operate at different spatial scales. We discuss how these properties may function in regulating the interactions among organisms and the biogeochemical processes that they mediate. It is through the formation of a spatially and temporally heterogeneous structure that biodiversity may contribute most significantly to the functioning of soil ecosystems.
Real advances in understanding the significance of biodiversity to biogeochemical cycling will come from taking a broader view of biodiversity. Such a view will necessarily encompass many levels of resolution including: 1) the importance of biodiversity to specific biogenic transformations, 2) the complexity and specificity of biotic interactions in soils that regulate biogeochemical cycling, and 3) how biodiversity may operate at different hierarchically arranged spatial and temporal scales to influence the structure and function of ecosystems.
Although it has been recognized that the adsorption of organics to clay and silt particles is an important determinant of the stability of organic matter in soils, no attempts have been made to quantify the amounts of C and N that can be preserved in this way in different soils. Our hypothesis is that the amounts of C and N that can be associated with clay and silt particles is limited. This study quantifies the relationships between soil texture and the maximum amounts of C and N that can be preserved in the soil by their association with clay and silt particles. To estimate the maximum amounts of C and N that can be associated with clay and silt particles we compared the amounts of clay- and silt-associated C and N in Dutch grassland soils with corresponding Dutch arable soils. Secondly, we compared the amounts of clay- and silt-associated C and N in the Dutch soils with clay and silt-associated C and N in uncultivated soils of temperate and tropical regions.
We observed that although the Dutch arable soils contained less C and N than the corresponding grassland soils, the amounts of C and N associated with clay and silt particles was the same indicating that the amounts of C and N that can become associated with this fraction had reached a maximum. We also observed close positive relationships between the proportion of primary particles < 20 μm in a soil and the amounts of C and N that were associated with this fraction in the top 10 cm of soils from both temperate and tropical regions. The observed relationships were assumed to estimate the capacity of a soil to preserve C and N by their association with clay and silt particles. The observed relationships did not seem to be affected by the dominant type of clay mineral. The only exception were Australian soils, which had on average more than two times lower amounts of C and N associated with clay and silt particles than other soils. This was probably due to the combination of low precipitation and high temperature leading to low inputs of organic C and N.
The amount of C and N in the fraction > 20 μm was not correlated with soil texture. Cultivation decreased the amount of C and N in the fraction > 20 μm to a greater extent than in the fraction < 20 μm, indicating that C and N associated with the fraction < 20 μm is better protected against decomposition.
The finding of a given soil having a maximum capacity to preserve organic C and N will improve our estimations of the amounts of C and N that can become stabilized in soils. It has important consequences for the contribution of different soils to serve as a sink or source for C and N in the long term.
Crop-based agriculture occupies 1.7 billion hectares, globally, with a soil C stock of about 170 Pg. Of the past anthropogenic CO2 additions to the atmosphere, about 50 Pg C came from the loss of soil organic matter (SOM) in cultivated soils. Improved management practices, however, can rebuild C stocks in agricultural soils and help mitigate CO2 emissions.
Increasing soil C stocks requires increasing C inputs and/or reducing soil heterotrophic respiration. Management options that contribute to reduced soil respiration include reduced tillage practices (especially no-till) and increased cropping intensity. Physical disturbance associated with intensive soil tillage increases the turnover of soil aggregates and accelerates the decomposition of aggregate-associated SOM. No-till increases aggregate stability and promotes the formation of recalcitrant SOM fractions within stabilized micro- and macroaggregate structures. Experiments using13 C natural abundance show up to a two-fold increase in mean residence time of SOM under no-till vs intensive tillage. Greater cropping intensity, i.e., by reducing the frequency of bare fallow in crop rotations and increasing the use of perennial vegetation, can increase water and nutrient use efficiency by plants, thereby increasing C inputs to soil and reducing organic matter decomposition rates.
Management and policies to sequester C in soils need to consider that: soils have a finite capacity to store C, gains in soil C can be reversed if proper management is not maintained, and fossil fuel inputs for different management practices need to be factored into a total agricultural CO2 balance.
The objectives of this study were: (1) to quantify the effects of plant species' loss from designed calcareous grassland communities
at a field site in northwestern Switzerland on the size and composition of earthworm communities, and (2) to evaluate how
exposure of plant communities to elevated atmospheric CO2 might alter the effects of plant species' loss on earthworm communities.
We non-destructively censused earthworm communities in each of 24 1.2 m2 experimental plots in autumn 1996 when soils were
wet and earthworms were active. Each plot contained an experimental plant community with 31, 12 or 5 native plant species
(eight plots each). Half of the plots in each species treatment were exposed to ambient CO2 concentrations (350 μL CO2 L-1)
and half to elevated CO2 (600 μL CO2 L-1) using screen-aided CO2 control. The study was conducted in the fourth year after
community establishment and the third year of CO2 treatment as part of a long-term study on the interactive effects of plant
species' loss and elevated CO2 on grassland communities. The size (density and biomass) of earthworm communities declined
linearly when the number of plant species in the community was reduced from 31 to 5 species (e.g. 32 ± 1 g m-2 to 23 ± 2 g
m-2) due mainly to a decline in the endogeic worm species Allolobophora rosea which was the most abundant of nine earthworm
species observed (nearly half of all worms in each plot). However, no changes in the relative contribution of individual species
or the three main earthworm ecological groups (anecics, endogeics, epigeics) to the entire earthworm community were observed
with declining number of plant species. The responses of earthworm communities to plant species'; loss appear to reflect changes
in community fine root biomass in the topsoil (e.g. declining worm biomass with declining fine root biomass) observed in parallel
studies conducted at this site. Further the results of this study demonstrate that a loss of plant species from these calcareous
grassland communities may also alter the age structure of earthworm communities, but not significantly influence their diversity
or composition. Our data also indicate that rising atmospheric CO2 may not greatly impact the size and composition of worm
communities or alter the effects of plant species' loss on earthworm communities. Therefore, the disappearance of plant species
from these native grasslands, as a result of ever increasing human activities, may be expected to lead to reductions in the
size of earthworm communities and the ecosystem services they provide.
We examined the impact of biodiversity on litter decomposition in an experiment that manipulated plant species richness. Using biomass originating from the experimental species richness gradient and from a species used as a common substrate, we measured rates of decomposition in litterbags in two locations: in situ in the experiment plots and in an adjacent common garden. This allowed us to separate the effects of litter quality and decomposition location on decomposition. We found that plant species richness had a significant, but minor negative effect on the quality (nitrogen concentration) of the biomass. Neither litter type nor location had a consistent effect on the rate of carbon and nitrogen loss over a 1-year period. Thus, the increased productivity and corresponding lower soil available nitrogen levels observed in high diversity plots do not lead to faster litter decomposition or faster nitrogen turnover. This supports the hypothesis that increased productivity corresponding with higher species richness results in increased litter production, higher standing litter pools and a negative feedback on productivity, because of an increased standing nitrogen pool in the litter.
The rapidly growing scientific literature on various aspects of carbon storage in soils has given rise to the introduction of several terms when discussing the amounts of carbon that are, or could be, stored in soils. The term “carbon sequestration potential”, in particular, is used with different meanings, sometimes referring to what might be possible given a certain set of management conditions with little regard to soil factors which fundamentally determine carbon storage. An attempt is made to clarify some of the main issues by adopting terminology developed in plant physiology and crop modelling research. This, together with examples from the tropics, is used to clarify some of the issues as relating to mineral soils. The term “Attainablemax” is defined and is suggested as the preferred term for carbon sequestration in mineral soils, being more relevant to management than “potential” and thereby of greater practical value.
The relative effects of plant richness (the number of plant functional groups) and composition (the identity of the plant
functional groups) on primary productivity and soil nitrogen pools were tested experimentally. Differences in plant composition
explained more of the variation in production and nitrogen dynamics than did the number of functional groups present. Thus,
it is possible to identify and differentiate among potential mechanisms underlying patterns of ecosystem response to variation
in plant diversity, with implications for resource management.
Ecologists are expected to play an important role in future studies of the biosphere/atmosphere exchange of materials associated with the major biogeochemical cycles and climate. Most studies of material exchange reported in the ecological literature have relied on chamber techniques. Micrometeorological techniques provide an alternative means of measuring these exchange rates and are expected to be used more often in future ecological studies, since they have many advantages over the chamber techniques. In this article we will provide an overview of micrometeorological theory and the different micrometeorological techniques available to make flux measurements.
Carbon exchange between the terrestrial biosphere and the atmosphere is
one of the key processes that need to be assessed in the context of the
Kyoto Protocol. Several studies suggest that the terrestrial biosphere
is gaining carbon, but these estimates are obtained primarily by
indirect methods, and the factors that control terrestrial carbon
exchange, its magnitude and primary locations, are under debate. Here we
present data of net ecosystem carbon exchange, collected between 1996
and 1998 from 15 European forests, which confirm that many European
forest ecosystems act as carbon sinks. The annual carbon balances range
from an uptake of 6.6 tonnes of carbon per hectare per year to a release
of nearly 1 t C ha -1 yr-1, with a large
variability between forests. The data show a significant increase of
carbon uptake with decreasing latitude, whereas the gross primary
production seems to be largely independent of latitude. Our observations
indicate that, in general, ecosystem respiration determines net
ecosystem carbon exchange. Also, for an accurate assessment of the
carbon balance in a particular forest ecosystem, remote sensing of the
normalized difference vegetation index or estimates based on forest
inventories may not be sufficient.
Six reasonable models of trophic exploitation in a two-species ecosystem whose exploiters compete only by depleting each other's
resource supply are presented. In each case, increasing the supply of limiting nutrients or energy tends to destroy the steady
state. Thus man must be very careful in attempting to enrich an ecosystem in order to increase its food yield. There is a
real chance that such activity may result in decimation of the food species that are wanted in greater abundance.
I examine, through an extensive compilation of published reports, the nature and variability of carbon flow (i.e., primary production, herbivory, detrital production, decomposition, export, and biomass and detrital storage) in a range of aquatic and terrestrial plant communities. Communities composed of more nutritional plants (i.e., higher nutrient concentrations) lose higher percentages of production to herbivores, channel lower percentages as detritus, experience faster decomposition rates, and, as a result, store smaller carbon pools. These results suggest plant palatability as a main limiting factor of consumer metabolical and feeding rates across communities. Hence, across communities, plant nutritional quality may be regarded as a descriptor of the importance of herbivore control on plant biomass ("top-down" control), the rapidity of nutrient and energy recycling, and the magnitude of carbon storage. These results contribute to an understanding of how much and why the trophic routes of carbon flow, and their ecological implications, vary across plant communities. They also offer a basis to predict the effects of widespread enhancement of plant nutritional quality due to large-scale anthropogenic eutrophication on carbon balances in ecosystems.
This executive summary presents the major findings of the synthesis of the first six years of the Global Change and Terrestrial Ecosystems (GCTE) Core Project of the IGBP (see Appendix I). It begins by identifying the major components and drivers of global change. It then outlines the important ecosystem interactions with global change, focusing on the functioning of ecosystems and the structure and composition of vegetation. The executive summary then discussed the implications of these ecosystem interactions with global change in terms of impacts in three key areas: managed production systems, biodiversity and the terrestrial carbon cycle. The full synthesis results and conclusions, with a complete reference list, are presented as a volume in the IGBP Book Series No 4, published by Cambridge University Press (Walker et al. [In Press]). Here key references only are included.
1. The effects of the grass species Lolium perenne L. and nine dicotyledonous grass-land species, grown in monocultures and two-species mixtures, on (i) the soil microbial biomass, (ii) the respiration: biomass ratio and (iii) plant litter decomposition was investigated in a glasshouse experiment. 2. Microbial biomass was sometimes greater and sometimes less in the two-species mixtures than could be explained in terms of the additive effects of the two component species grown singly; this variation was independent of differences in below-ground plant productivity between monoculture and mixture treatments. 3. The microbial respiration: biomass ratios and plant litter decomposition rates in the two-species mixture treatments were either greater or less than expected based on the monoculture treatments; these differences were dependent on the combinations of species present. Because the respiration: biomass ratio is a measure of ecosystem stability, it is here proposed that stability does not respond predictably to shifts in species diversity. 4. These results provide evidence that increasing plant species richness (from one to two species) has the potential to influence soil processes positively or negatively in a non-additive way. The possible ecological implications of this are discussed.
There has been a rapidly increasing recent interest in the effects of biological diversity on ecosystem properties, and while some studies have recently concluded that biodiversity improves ecosystem function, these views are based almost entirely on experiments in which species richness of live plants has been varied over all the species diversity treatments. However, most net ecosystem primary productivity eventually enters the decomposition subsystem as plant fitter where it has important ''afterlife effects''. We conducted a field experiment in which litter from 32 plant species (i.e. eight species of each of four plant ''functional groups'' with contrasting litter quality) was collected and placed into litter-bags so that each litter-bag contained between one and eight species; the species which were included in the multiple (greater than or equal to 2) species litter-bags were randomly selected. This litter diversity gradient was created within each functional group and across some functional groups. We found large non-additive effects of mixing litter from different species on litter decomposition rates, litter nitrogen contents, rates of nitrogen release from litter and the active microbial biomass present on the litter. The patterns and directions of these non-additive effects were dependent upon both plant functional group and lime of harvest, and these effects could be predicted in some instances by the initial litter nitrogen content and the degree of variability of nitrogen content of the component species in the litter-bag. There was no relationship between litter-bag species richness and any of the response variables that we considered, at least between two and eight species. Within plant functional groups our results provide some support for the species redundancy and idiosyncratic hypotheses about how biodiversity alters ecosystem function, but no support for the ecosystem rivet hypothesis or the view that species richness of plant litter is important for ecosystem function. We suggest that increased species diversity of plant litter is less important than that of live plants for determining ecosystem properties (and provide possible reasons for this) and conclude that perceived relationships between biodiversity and ecosystem function may be of diminished significance when the ecological importance of plant litter is fully appreciated.