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In spite of overwhelming experimental evidence to the contrary, rotational grazing continues to be promoted and implemented as the only viable grazing strategy. The goals of this synthesis are to 1) reevaluate the complexity, underlying assumptions, and ecological processes of grazed ecosystems, 2) summarize plant and animal production responses to rotational and continuous grazing, 3) characterize the prevailing perceptions influencing the assessment of rotational and continuous grazing, and 4) attempt to direct the profession toward a reconciliation of perceptions advocating support for rotational grazing systems with that of the experimental evidence. The ecological relationships of grazing systems have been reasonably well resolved, at the scales investigated, and a continuation of costly grazing experiments adhering to conventional research protocols will yield little additional information. Plant production was equal or greater in continuous compared to rotational grazing in 87% (20 of 23) of the experiments. Similarly, animal production per head and per area were equal or greater in continuous compared to rotational grazing in 92% (35 of 38) and 84% (27 of 32) of the experiments, respectively. These experimental data demonstrate that a set of potentially effective grazing strategies exist, none of which have unique properties that set one apart from the other in terms of ecological effectiveness. The performance of rangeland grazing strategies are similarly constrained by several ecological variables establishing that differences among them are dependent on the effectiveness of management models, rather than the occurrence of unique ecological phenomena. Continued advocacy for rotational grazing as a superior strategy of grazing on rangelands is founded on perception and anecdotal interpretations, rather than an objective assessment of the vast experimental evidence. We recommend that these evidence-based conclusions be explicitly incorporated into management and policy decisions addressing this predominant land use on rangelands.
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... Periods of rest following removal of livestock grazing pressure are thought to allow enhanced root development which enables rapid regrowth of herbage following infrequent defoliations, compared to smaller root systems and permanently low leaf photosynthetic area under continuous grazing pressure (Sanderman et al., 2015;Hacker, 1993;Voisin, 1959;Savory and Butterfield, 2016). Further, decreasing the area available to livestock at any one time through subdivision of pasture into paddocks may reduce selectivity of animal grazing, preventing less palatable species from dominating the sward and deteriorating forage quality, plus achieving more uniform distribution of livestock manure and urine across the pasture (Briske et al., 2008;Norton, 1998). These effects are believed to be accentuated under longer rest periods, typically corresponding with shorter grazing periods and higher stocking densities to match forage availability with livestock requirements. ...
... These effects are believed to be accentuated under longer rest periods, typically corresponding with shorter grazing periods and higher stocking densities to match forage availability with livestock requirements. However, although these mechanisms are plausible and convincing to many land managers, they are predominantly based on scientific theory, and the currently available scientific evidence has been found to be inconclusive for USA rangelands (Briske et al., 2008;Briske et al., 2011a;Briske et al., 2011b). ...
... The key aspects of grazing systems that are likely to affect pasture productivity and livestock performance are the duration of grazing and recovery periods, and the stocking density during the grazing period (Voisin, 1959;Briske et al., 2008;Briske et al., 2011a;Techio Pereira et al., 2018). Simply analysing grazing practice as a predictor with two levels (rotational vs continuous grazing) is inappropriate for the diversity of management practices included within RG (Sanderman et al., 2015). ...
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Reducing greenhouse gas emissions associated with ruminant livestock production is important for climate change mitigation. Regenerative Agriculture (RA) practices are increasingly promoted to improve forage production and livestock performance in temperate livestock systems. These practices include i) rotational grazing (RG) of livestock around multiple subunits of pasture to achieve ungrazed periods of ‘rest’, and ii) herbal leys (HL), where perennial forbs such as chicory, lucerne and trefoils are included as components in multi-species swards. While there are plausible mechanisms for adoption of these practices to improve agricultural productivity, quantitative syntheses of their impacts are required. Here, we conduct a systematic review and meta-analysis of the effects of RG and HL practices on herbage dry matter (DM) production, animal daily liveweight gain (DLWG), and sheep wool growth in temperate oceanic regions. We use quantitative predictors in our Bayesian hierarchical models to investigate the role of rest period and stocking density in RG systems, and specific plant traits and sward diversity in HL. We found that herbage DM increased by 0.31 t.ha⁻¹ over a growing season as the proportion of rest in an RG grazing system increased from 0 to 1. Stocking density significantly moderated the effect of rest period on sheep and cattle DLWG; at higher stocking densities, longer rest periods were required to maintain livestock growth rates. In HL studies, herbage DM yielded 1.63 t.ha⁻¹ more per metre of increased sward root depth and a sward entirely comprised of legumes yielded 2.20 t.ha⁻¹ more than when no legumes were present. Sheep DLWG increased by 3.50 g.day⁻¹ per unit increase in leaf nitrogen concentration (mg.g⁻¹), but we could not determine an effect of leaf condensed tannin content on animal performance. Although there remain differences between the RG and HL study treatments meta-analysed here and RA in practice, our results provide empirical support for some of the mechanisms attributed to increased pasture and livestock productivity following adoption of selected RA grazing practices.
... A grazing system growing in popularity among ranchers, known as Adaptive Multi-Paddock (AMP) grazing, employs high animal densities within small areas for short periods of time (Briske et al., 2008) followed by a long recovery period before subsequent grazing . In theory, this practice allows heightened control for land managers to target how long, and at what intensity, livestock grazing occurs (Briske et al., 2008;Teague et al., 2013). ...
... A grazing system growing in popularity among ranchers, known as Adaptive Multi-Paddock (AMP) grazing, employs high animal densities within small areas for short periods of time (Briske et al., 2008) followed by a long recovery period before subsequent grazing . In theory, this practice allows heightened control for land managers to target how long, and at what intensity, livestock grazing occurs (Briske et al., 2008;Teague et al., 2013). AMP grazing is intended to emulate aspects of the historical grazing patterns of herding ruminants, and thus restore ecological functioning (Savory, 1983). ...
... The uniform disturbance of vegetation through animal consumption and trampling by hooves associated with AMP contrasts with patchier grazing commonly observed in conventional systems (Chamane et al., 2017). AMP grazing should cause more uniform (i.e. less selective) pressure on plants, as is typical of grazing lawns (McNaughton, 1984), thereby reducing microsite heterogeneity and niche space (Briske et al., 2008). Thus, regardless of the influence of AMP grazing on local and landscape diversity, it would be expected to lead to higher species evenness within plots and lower beta diversity among plots. ...
Article
Grassland plant community structure and function are dependent on the type, timing, frequency and intensity of disturbance. Grazing systems employing dense herds of livestock for short periods of time (e.g. Adaptive Multi‐paddock Grazing; AMP) are gaining popularity as a potentially sustainable practice. Effects of AMP systems on plant diversity and composition are unknown, though theory provides some expectations. Spatially homogeneous grazing used by AMP may be a uniform ecological filter, thereby lowering plant diversity; alternatively, the AMP practice of using multiple paddocks might enhance habitat heterogeneity. Maintaining plant diversity, particularly of native species, is a key aspect of sustainability. As such, an understanding of the real‐world effects of AMP grazing is needed. We studied grasslands within 18 pairs of ranches across the northern Great Plains. Ranches managed under AMP were paired with a neighbouring ranch (N‐AMP) using regionally representative grazing practices. We collected surveys of management practices and conducted 2 years of on‐farm sampling to identify plant composition and diversity. Ranch management practices used by self‐identified AMP ranchers differed significantly (p < 0.1) from those used on neighbouring ranches, with higher stocking densities (number of animals per area at a single time) but not stocking rates (total number of animals per unit time per area) on AMP relative to N‐AMP ranches. There were fewer plant species in AMP grasslands at both the plot and landscape scales compared to N‐AMP ranches despite no overall difference in plant community composition. Management type did not alter the variability of plant community composition (beta diversity) or plot‐level species evenness. Although there were trends for lower diversity of native and introduced species at both spatial scales, a significant effect was found only for native species at the landscape scale. Synthesis and applications. The impacts of AMP grazing system management were limited to a minor reduction in plant diversity, with a modest decline in native species richness. We conclude that the benefits of AMP grazing in the northern Great Plains do not include the maintenance of plant diversity, and this system could hinder the conservation of remaining native plant species. The impacts of AMP grazing system management were limited to a minor reduction in plant diversity, with a modest decline in native species richness. We conclude that the benefits of AMP grazing in the northern Great Plains do not include the maintenance of plant diversity, and this system could hinder the conservation of remaining native plant species.
... The purported underlying reason for this is that high animal densities allow for longer rest periods for plants and create a phenomenon called the "Herd effect" or "Hoof effect" in which animals trample vegetation and incorporate it into the soil surface (Burleson and Leininger, 1988;Savory and Butterfield, 2016;Warren et al., 1986). However, most previous research examining livestock management on soil has accounted only for stocking rate and not stocking density (Briske et al., 2008;Wang et al., 2015;Warren et al., 1986). Stocking rate (number of cattle/area/time) is a standard measure of grazing (forage use) intensity and is considered one of the most important livestock management metrics affecting soil microbial communities (Wakelin et al., 2009), plant productivity (Briske et al., 2008) and animal production (Venter et al., 2019). ...
... However, most previous research examining livestock management on soil has accounted only for stocking rate and not stocking density (Briske et al., 2008;Wang et al., 2015;Warren et al., 1986). Stocking rate (number of cattle/area/time) is a standard measure of grazing (forage use) intensity and is considered one of the most important livestock management metrics affecting soil microbial communities (Wakelin et al., 2009), plant productivity (Briske et al., 2008) and animal production (Venter et al., 2019). However, the response of microbial communities to stocking rates is not consistent; for example, microbial biomass can decrease or increase, with increasing stocking rate (Banerjee et al., 2000;Bardgett and Wardle, 2003;Harrison and Bardgett, 2004;Wang et al., 2006). ...
Article
Grasslands are used extensively for grazing livestock, and variation in grazing management may affect the soil microbial community and ecosystem functions, such as nutrient cycling, in grasslands. In particular, adaptive multi-paddock (hereafter ‘multi-paddock’) grazing is considered a regenerative grazing management practice that can improve the sustainability of grasslands. However, little is known about how multi-paddock grazing affects the soil microbial community, which plays an importance role in global biogeochemical cycling. In this study, grassland soils were collected from 15 ranch pairs located across the Canadian prairie, where, in each pair, one ranch practiced multi-paddock grazing while the other practiced conventional grazing (varying from continuous to slow to fast rotational grazing). We used soil phospholipid fatty acid (PLFA) profiles to quantify microbial functional groups, and measured microbial biomass C and soil properties. Our data show that microbial PLFA abundances and microbial biomass C was not different between the two grazing systems. However, multi-paddock grazing resulted in lower ratios of microbial biomass C: N (MBC:MBN), fungi: bacteria (F:B) and Gram-positive: Gram-negative bacteria in grassland soils compared to conventional grazing. Further investigation of specific management metrics revealed that MBC:MBN and F:B ratios were most affected by cattle stocking rate and stocking density, respectively. Thus, there is potential to affect soil function by altering the composition of soil microbial communities through multi-paddock grazing.
... Although there is still debate in and outside academia about which stocking method is the best, the majority of peer-reviewed literature has shown that differences concern the extent of control humans exerts over the defoliation process (i.e., how the spatio-temporal distribution of the herd affects the frequency, intensity and uniformity of the defoliation process) rather than productive or ecological outcomes, as long as the same grazing intensities are under comparison (Briske et al., 2008;Hawkins et al., 2022). Recently, data from a long-term ICLS (10 years) in southern Brazil found that total herbage production and its availability to animals (i.e., forage budgeting) are more important than the stocking method to increase sheep live weight (LW) production per hectare (Moojen et al., 2021). ...
Article
The Rio de la Plata region (Argentina, Uruguay, and southern Brazil) is currently characterized by a mosaic of intensively managed croplands and remaining areas of livestock production on native grasslands. The production of crops and animals in this scenario is usually spatially segregated as a result of mindset and structural constraints developed over decades of agricultural specialization. However, several studies have suggested that crop-livestock integration across various spatio-temporal scales can improve land-use efficiency and ecosystem services provisioning. In this context, the long-standing tradition of Rio de la Plata region’s ranchers on sheep production summed to the easy-to-manage body size of these small ruminants make them fit into a wide range of farm sizes and integrated crop-livestock system (ICLS) designs. In addition, the large variety of crops produced in the region, including annual (e.g., soybean, maize, rice and wheat) and perennial (e.g., orchards, vineyards and woodlands), and the diversity of temperate and tropical forage species used in livestock systems, provide multiple ICLS possibilities. In this review, we explore these possibilities and highlight the opportunities and challenges for integration of crop and sheep production in the Rio de la Plata region of South America. Using mainly data from the region’s ICLS, but also other parts of the world, we show that ICLS with sheep are able to improve nutrient cycling, land-use efficiency, and systems’ resilience and profitability if sound grazing intensities are used. Finally, we build on the idea of ICLS farm design to present an interactive, hands-on methodology recently developed to support farmers’ transition from specialized systems to ICLS.
... Livestock move across landscapes in response to abiotic and biotic factors, which vary at a variety of spatial and temporal scales (Bailey et al. 1996, Cheleuitte-Nieves et al. 2020, thus the severity of grazing effects may vary over time (Pastor et al. 1997) or in response to spatial movements of grazers (Briske et al. 2008). Available water, forage quality, disturbance, and topography influence livestock distribution and subsequently, grazing effects, even when the number of animals and timing of grazing is the same (Bailey et al. 1996, Belsky et al. 1999, Bailey 2004. ...
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Livestock grazing is a globally important land‐use and has the potential to significantly influence plant community structure and ecosystem function, yet several critical knowledge gaps remain on the direction and magnitude of grazing impacts. Furthermore, much of our understanding of the long‐term effects on plant community composition and structure are based on grazer exclusion experiments, which explicitly avoid characterizing effects along grazing intensity gradients. We sampled big sagebrush plant communities using 68 plots located along grazing intensity gradients to determine how grazing intensity influences multiple aspects of plant community structure over time. This was accomplished by sampling plant communities at different distances from 17 artificial watering sources, using distance from water and cow dung density as proxies for grazing intensity at individual plots. Total vegetation cover and total grass cover were negatively related to grazing intensity, and cover of annual forbs, exotic cover, and exotic richness were positively related to grazing intensity. In contrast, species richness and composition, bunchgrass biomass, shrub density and size, percentage cover of bare ground, litter, and biological soil crusts did not vary along our grazing intensity gradients, in spite of our expectations otherwise. Our results suggest that the effects of livestock grazing over multiple decades (mean = 46 years) in our sites are relatively small, especially for native perennial species, and that the big sagebrush plant communities we sampled are somewhat resistant to livestock grazing. Collectively, our findings are consistent with existing evidence that indicates stability of big sagebrush plant functional type composition under current grazing management regimes.
... Grassland grazing management's core is balancing the supply of grassland forage and livestock forage demand (Tan, Zhang, et al. 2018;Cao et al. 2019). The two mature theories about the relationship between grazing intensity and grassland productivity are the descending type (Briske et al. 2008) and inverted "U" type (Klein, Pinares-Patino, and Waghorn 2008;McNaughton 1979). According to the first theory, an increase in grazing intensity will lead to a decline in grassland primary productivity. ...
Article
Achieving coordination between grassland ecological conservation and livestock production is a global concern. Based on the survey data for 818 herders in China, we empirically analyzed grassland rental’s (GR) impact on herders’ technical efficiency (TE) and overgrazing under a unified framework. Results indicate that GR offers concurrent benefits of improving TE and reducing overgrazing; it helps to achieve a win-win situation between livestock production and grassland conservation. However, GR does little to promote TE by reducing overgrazing. Further analysis reveals that GR’s promotion effect on TE and the inhibition effect on overgrazing are heterogeneous among different income groups and grassland types. GR plays a stronger role in improving TE and reducing overgrazing by low-income herders, which is conducive in narrowing the animal husbandry development gap between rich and poor. The key policy implication is that GR should be encouraged under the condition of strengthening supervision.
... Their contributions have enabled pastoralism to be rehabilitated, believing that it is not sufficiently influential in the sustainable degradation of such an environment. Conversely, it even appears that the mobility strategies implemented by pastoralists are likely to counteract environmental risks (Morton & Meadows, 2000;Briske et al., 2008). ...
... Grazing intensity from low to high degree Soil organic C − (Su et al. 2005;Li et al. 2008;Steffens et al. 2008;Wiesmeier et al. 2009) Total N − (Su et al. 2005;Li et al. 2008;Steffens et al. 2008;Wiesmeier et al. 2009) Total S (sulfur) − (Steffens et al. 2008;Wiesmeier et al. 2009) Total P − ) Soil biological characteristics (including some enzyme activities) and soil respiration − (Su et al. 2005) Soil bulk density + Steffens et al. 2008;Wiesmeier et al. 2009) Soil available P, available N (NO 3 − and NH 4 + ) No Lin et al. 2010aLin et al. , 2010b Electrical conductivity, pH value or concentration of soluble ions (Na + , K + , Ca 2+ , Mg 2+ , Cl − and SO 4 2− ) No Aboveground plant biomass − Wiesmeier et al. 2009) Living root biomass and belowground net primary productivity − (Gao et al. 2008) Continuous VS rotational grazing Plant production ≥ (Briske et al. 2008) Exclusion of livestock grazing Vegetation restoration, litter accumulation and the growth of annual and perennial grasses + (Su et al. 2005) evaluation variables, net primary productivity (NPP) is one of the key indicators Yang et al. 2016;Zhou et al. 2017b) to assess the grasslands status. There are also other indicators, such as grassland species composition, grassland desertification, and aboveground biomass (AGB) (Wang et al. 2017;Han et al. 2018a) in grassland evaluation. ...
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Purpose Grasslands are the largest type of terrestrial ecosystem on the earth, providing rich and unique ecosystem services. However, climate change and human activities have triggered a global degradation of grasslands, which has become a major ecological crisis. In this study, a scientometric analysis was performed to explore the hotspots and frontiers of global grassland degradation research. Materials and methods Two methods involving visualization were used to analyze these data: document co-citation analysis and burst analysis based on the papers indexed in the Web of Science (WOS) during 1970–2020. Results and discussion A total of 3580 research papers related to grassland degradation research and 54,666 references were included. The results showed that Harris’s paper in 2010 had the strongest burst value of 26.2, far larger than any other, which shows that this paper was a turning point in the research process. The document co-citation network was divided into 14 main theme clusters. The most influential and emerging research theme clusters were including alpine meadow, grazing exclusion, alpine region, and human activities. Alpine meadow was the largest cluster lasting from 2010 to 2020, indicating that this topic is still active in grassland degradation research. Furthermore, research focus has transferred toward grasslands in Qinghai-Tibetan Plateau. The topic of grazing exclusion is both classic and currently active as it lasted as a research hotspot for 15 years (2004–2018). However, the extent and state of grazing effects research are unclear. Conclusions As the first scientometric review on grassland degradation research, our study identified the research hotspots and their shifts over the past 50 years, pointing to some potential research frontiers in the future. The scientometric analysis is a useful tool for a quantitative evaluation of research hotspots and trends of global grassland degradation.
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Background Measurement of two grazing management’s influence on pasture productivity, soil food web structure, soil organic carbon and soil microbial respiration efficiency was conducted on five southeastern US, across-the-fence ranch pairs to compare adaptive multi-paddock grazing (AMP) management, using short grazing events with planned, adaptive recovery periods, to conventional grazing (CG) management, with continuous grazing at low stock density. Methodology A point-in-time experimental field analysis was conducted to compare five AMP or CG ranch pairs to better understand the influence of grazing management on (a) standing crop biomass productivity; (b) soil food web community population, structure and functionality; (c) soil organic carbon accrual; and d) soil-C (CO 2 ) respiration kinetics. Results AMP grazing systems outperformed CG systems by generating: (a) 92.68 g m ⁻² more standing crop biomass (SCB), promoting 46% higher pasture photosynthetic capacity (Two sample Mann-Whitney; Z = 6.1836; no DF in MW; p = 6.26 × 10 ⁻¹⁰ ; Effect size = 0.35) (b) a strong positive linear relationship of SCB with fungal biomass (R = 0.9915; F(1,3) = 175.35; p = 0.015); fungal to bacterial (F:B) biomass ratio (R = 0.9616; F(1,3) = 36.75; p = 0.009) and a soil food web proxy (R = 0.9616; F(1,3) = 36.75; p = 0.009) and a concurrent very strong inverse relationship with bacteria biomass (R = −0.946; F(1,3) = 25.56; p = 0.015); (c) significant predator/prey interactions with an inverse relationship with bacterial population biomass ( R = − 0.946; F(1,3) = 25.56; p = 0.015) and a positive relationship with total protozoa enumeration (R = 0.9826; F(1,3) = 83.68; p = 0.003) when compared to SCB; (d) a 19.52% reduction in soil C (CO 2 ) respiration rates (Two sample t -test; T = −2.3581; DF = 52.3541; p = 0.0221; Effect size = 0.59); and (e) a 20.6% increase in soil organic carbon (SOC) in the top 10 cm of soil profile (Two sample Mann–Whitney; Z = 2.6507; no DF in MW; p = 0.008; Effect size = 0.24). Rancher conversion to AMP grazing strategies would appear to regenerate soil food web population, structure, diversity and biological functionality helping to improve: carbon flow into plant biomass, buildup of soil carbon, predator/prey nutrient cycling and soil microbial respiration efficiency while offering improved climate resilience and a strategy to increase the capture and storage of atmospheric CO 2 in soils of the world’s rangeland.
Article
The Thick-billed Longspur (Rhynchophanes mccownii) is a bird species of conservation concern that relies on shortgrass prairies and steppes of western North America. These habitats have been greatly altered from expansive and diverse ecosystems into small patches of homogeneous pastures interspersed with agricultural lands, yet little information exists on how land use affects Thick-billed Longspur demography. This study evaluates the benefits of an incentivized private land conservation-based program (CBP) on Thick-billed Longspur reproduction. We compared Thick-billed Longspur nest success and density on data collected on pastures enrolled in CBP with pastures not enrolled. CBP pastures experienced a restrotation specified grazing regime, while there were no requirements for the pastures outside the program. We use a time-to-event state-space superpopulation model that accounts for the availability of nests when estimating detection. We detected and monitored 74 Thick-billed Longspur nests over 2 breeding seasons, including 28 nests in CBP pastures. Our results suggest similar estimates of nest success and nest density between nests in CBP pastures and nests in pastures not participating in the conservation program. Our estimates of nest success and nest density advance our understanding of the influence of an incentivized conservation program on songbirds and give insight into 2 metrics of Thick-billed Longspur reproduction. El escribano Rhynchophanes mccownii es una especie con estatus de conservacin preocupante que depende de praderas bajas y estepas del occidente de Norteamrica. Estos hbitats han sido grandemente alterados de ser ecosistemas dominantes y diversos a pequeos parches de pasturas homogneas mezcladas con tierras agrcolas. Sin embargo, existe poca informacin de cmo el uso del suelo afecta la demografa de estos escribanos. Este estudio evala los beneficios de un programa que incentiva la conservacin de tierras privadas (CBP) en la reproduccin del escribano. Comparamos el xito de anidacin y densidad segn datos colectados en pasturas que se inscribieron en un CBP con aquellas de pasturas que no formaban parte del programa. Las pasturas en el CBP experimentaron un rgimen especfico de pastoreo de descanso-rotacin, mientras que no hubo requisitos para las pasturas que no formaban parte del programa. Usamos un modelo de superpoblacin de estado-espacio que cuantifica la disponibilidad de nidos mientras estima su deteccin. Detectamos y monitoreamos 74 nidos de escribano a lo largo de 2 temporadas reproductivas, incluyendo 28 nidos en pasturas en el CBP. Nuestros resultados sugieren estimaciones similares de xito de anidacin y densidad de nidos entre nidos de pasturas en el CBP y los nidos en pasturas que no participaban en el programa de conservacin. Nuestras estimaciones de xito de anidacin y densidad de nidos avanzan nuestro entendimiento de la influencia de un programa de conservacin de pjaros con incentivos y da una visin en 2 mtricas de reproduccin del escribano. Palabras clave: aves canoras, densidad de nidos, escribano, xito de anidacin, ganado, pastoreo prescrito, reproduccin.
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We evaluated the adequacy of rotational grazing to improve rangeland condition in the Flooding Pampa region, eastern Argentina, comparing the floristic composition dynamic of the 2 main plant communities under rotational and continuous grazing over a study period of 4 years (1993-1996). The experiment was conducted in commercial farms located in 4 sites of the Flooding Pampa region. In each site, a couple of farms, one managed under rotational grazing (implemented in 1989) and an adjacent one managed under continuous grazing at a similar stocking rate (1 AU ha-1), constituted the replications of the experiment. Basal cover of species, litter, and bare soil were monitored in midslope and lowland grassland communities on each farm. Total plant basal cover in midslope and in lowland communities remained unchanged over the whole experimental period under both grazing methods. Under rotational grazing, litter cover was higher in both communities while the amount of bare soil showed a significant reduction in lowlands and a tendency to be lower in midslope. Basal cover of legumes, C3 annual and C3 perennial grasses was higher, while cover of C4 prostrate grasses was lower under rotational grazing in the midslope community. In the lowland community, rotational grazing effects were evident only in the drier years, when higher cover of hydrophytic grasses and legumes and lower cover of forbs occurred. Plant species diversity did not change in response to grazing. In conclusion, rotational grazing promoted functional groups composed of high forage value species and reduced bare soil through the accumulation of litter. These changes indicate an improvement in rangeland condition and in carrying capacity. As the stocking rate was approximately 60% higher than the average stocking rate of the Flooding Pampa region, we believe that productivity and sustainability may be compatible by replacing continuous with rotational grazing.
Chapter
Conventional ecological theory holds that grazing by livestock reduces productivity and alters botanical composition of rangeland plant communities. Changes in composition from that of the “climax” community are considered to be detrimental, but it is usually assumed that these changes will be reversed when grazing animals are removed. Reducing stocking rate and alternating periods of rest and grazing are attempts to mitigate undesirable effects of grazing. Recent research indicates that range ecosystems may retain their productivity and composition when grazed by livestock at seasons and stocking rates which resemble the grazing patterns under which the ecosystems evolved. Weather and fire may have more effect than grazing on productivity and composition, or may interact with grazing. In ecosystems with long-lived woody perennials, changes in composition may be reversible only after centuries or not at all. Finally, communities at early seral stages or communities including introduced plant species may be more productive than climax communities. All these findings indicate that protection of soil and maintenance of stable plant communities at whatever stage of succession may be more reasonable goals of grazing management than efforts to produce and maintain climax communities.