Large Domestic Herbivores Research Articles

Large herbivores facilitate an insect herbivore by modifying plant community composition in a temperate grassland.

Large herbivores often co‐occur and share plant resources with herbivorous insects in grassland ecosystems; yet, how they interact with each other remains poorly understood. We conducted a series of field experiments to investigate whether and how large domestic herbivores (sheep; Ovis aries) may affect the abundance of a common herbivorous insect (aphid; Hyalopterus pruni) in a temperate grassland of northeast China. Our exclosure experiment showed that 3 years (2010–2012) of sheep grazing had led to 86% higher aphid abundance compared with ungrazed sites. Mechanistically, this facilitative effect was driven by grazing altering the plant community, rather than by changes in food availability and predator abundance for aphids. Sheep significantly altered plant community by reducing the abundance of unpalatable forbs for the aphids. Our small‐scale forb removal experiment revealed an “associational plant defense” by forbs which protect the grass Phragmites australis from being attacked by the aphids. However, selective grazing on forbs by sheep indirectly disrupted such associational plant defense, making P. australis more susceptible to aphids, consequentially increasing the density of aphids. These findings provide a novel mechanistic explanation for the effects of large herbivores on herbivorous insects by linking selective grazing to plant community composition and the responses of insect populations in grassland ecosystems.

Synergistic effects of long-term herbivory and previous fire on fine-scale heterogeneity of prescribed grassland burns.

Grassland and savanna ecosystems, important for both livelihoods and biodiversity conservation, are strongly affected by ecosystem drivers such as herbivory, fire, and drought. Interactions among fire, herbivores and vegetation produce complex feedbacks in these ecosystems, but these have rarely been studied in the context of fuel continuity and resultant fire heterogeneity. We carried out 36 controlled burns within replicated experimental plots that had allowed differential access by wild and domestic large herbivores since 1995 in a savanna ecosystem in Kenya. Half of these were reburns of plots burned 5 yr previously. We show here that the fine-scale spatial heterogeneity of fire was greater in plots (1) previously burned, (2) accessible to large herbivores, and especially (3) these two in combination. An additional embedded experiment demonstrated that even small experimental burn-free patches can have strong positive effects on tree saplings, which experienced less damage during controlled burns and quicker postfire recovery. This work highlights the importance of simultaneously examining the interactions between fire and herbivory on fuel heterogeneity, which can have important impacts on the growth of woody saplings in savanna grasslands.

Tracing ancient animal husbandry in tropical Africa using the fossil spore assemblages of coprophilous fungi: a validation study in western Uganda

Fossil spores of coprophilous fungi preserved in lake and bog sediments are well-established palaeoecological tracers for the local history of pastoralism and other animal husbandry. However, applications in Africa are limited by the lack of information on the exact relationship between human activity and fungi growing on large-herbivore dung. Here we use 25 small crater-lake basins in western Uganda, which cover the complete regional gradient of natural vegetation and human impact intensity, as a natural laboratory to assess the relationship between coprophilous fungal spores recovered from recently deposited bottom sediments and the presence and abundance of large domestic herbivores in the surrounding crater basins. We find that the summed abundances of Sporormiella, Sordaria, Podospora and Delitschia, or of these four types plus Cercophora, are the most useful and robust fungal-spore indicators for the presence of domestic large herbivores in an East African context. Chaetomium could also be added to this list, particularly as it may help reduce stochasticity in the often low fossil counts of obligate coprophilous types. Our results suggest that domestic large herbivores, at least when associated with some degree of crop agriculture, leave a clearer signature on fungal-spore assemblages in the lakes’ sediments than large wildlife. Furthermore, they indicate that the typically small number of livestock kept by mixed-subsistence farmers leave a stronger imprint on fungal-spore assemblages than the much larger herds of specialist pastoralists occasionally visiting the lake to drink or bathe.

The motor cortex of the sheep: laminar organization, projections and diffusion tensor imaging of the intracranial pyramidal and extrapyramidal tracts.

The laminar organization of the motor cortex of the sheep and other large domestic herbivores received scarce attention and is generally considered homologous to that of rodents and primates. Thickness of the cortex, subdivision into layers and organization are scarcely known. In the present study, we applied different modern morphological, mathematical and image-analyses techniques to the study of the motor area that controls movements of the forelimb in the sheep. The thickness of the cortex resulted comparable to that of other terrestrial Cetartiodactyls (but thicker than in marine Cetartiodactyls of similar body mass). The laminar organization showed marked development of layer 1, virtual absence of layer 4, and image analysis suggested prevalence of large irregular neural cells in the deeper layers. Diffusion tensor imaging revealed robust projections from the motor cortex to the pyramids in the brainstem, and well evident tracts descending to the tegmentum of the mesencephalon and dorsal pons. Our data contrast the general representation of the motor system of this species, considered to be predominantly based on extra-pyramidal tracts that originate from central pattern generators in the brainstem.

Ungulates can control tree invasions: experimental evidence from nonnative conifers and sheep herbivory

Invasive conifer species are increasingly recognized as a serious problem in many parts of the world, where they are having large ecological and economic impacts. Understanding factors that trigger and can control invasion is key to management. Grazing and browsing by large herbivores have been suggested as a mechanism that may halt conifer invasions, although conflicting results have been reported (i.e. positive, negative or no effect of grazing on invasion). We believe that some of these opposing responses arise due to the absence of well-planned and replicated experiments, since current evidence is mostly observational, and for example, differences in animal densities can produce different results. Thus, in this study, we tested whether large herbivores can control invasion by nonnative conifers and whether the severity of the invasion process would be lessened by increased herbivory intensity. We evaluate experimentally herbivore damage on Pinus contorta, a highly invasive species in many countries of the Southern Hemisphere, under different sheep stocking rates in Patagonia, Argentina. We used four stocking rates, corresponding to 1, 2, 4 and 8 times the recommended sheep herbivory intensity for the study area. The response was not linear but rather presented a threshold. The greater stocking rate, the greater the browsing, higher reduction in seedling height, and decrease of survival of P. contorta. Also, the highest stocking rate damaged and killed 99% of them. This study provides evidence that large domestic herbivores can play a key role in the invasion process and, if managed properly, would provide a tool to help limit conifer invasion.

Grazing Intensity and Phenotypic Plasticity in the Clonal Grass Leymus chinensis

Phenotypic plasticity enables plants to cope with changes in their environment. Plasticity in a population of Leymus chinensis, a common grass species in arid and semiarid temperate grasslands of northern China, was determined in a natural grassland grazed by large domestic herbivores. We measured shoot and bud characteristics monthly along a grazing intensity gradient indicated by distance from the village gate during two growing seasons. In addition, some plants along the gradient were removed to a common transplant garden and their growth was compared. Leaf characteristics (leaf angle, leaf length, and leaf number), growth form (tiller height and tiller clusters), bud proliferation, and plant fitness differed significantly in situ along the gradient. The expression of plasticity was grazing intensity dependent: the greatest increase in tiller density, tiller cluster, and bud number occurred at a moderate grazing intensity (2.5 km from the village gate). In the transplant garden, no evidence was found for distinct populations of L. chinensis within the grassland. Leaf characteristics, tiller growth form, and bud demography of tillers not grazed showed phenotypic plasticity in response to grazing of neighbor shoots because clonal reproduction is the main breeding system for this species in grazed natural grassland and defoliation of neighbor shoots is likely to affect the physiology and morphology of tillers that are not grazed. The observed overcompensation in vegetative reproduction may aid future survival and growth and could be achieved in a prudent grazing system designed to take into account the needs of this dominant grass in semiarid temperate steppes.

Glade cascades: indirect legacy effects of pastoralism enhance the abundance and spatial structuring of arboreal fauna

Studies in community ecology are typically conducted over the span of a few years, and results are often interpreted as the product of contemporary processes and interactions. All landscapes have histories, however, and observed patterns of distribution and abundance frequently reflect enduring legacies of past ecological events, the existence and influence of which may not be obvious to investigators. In East Africa, most wildlife occurs outside national reserves and often coexists there with livestock, which are traditionally corralled at night in temporary thorn fence enclosures, or bomas. After being abandoned, bomas develop into nutrient‐rich, treeless glades that can persist for more than a century. These hotspots of primary productivity attract both native and domestic large herbivores, but the extent to which their effects cascade to other consumers is unknown. Here, we document positive edge effects of glades on the mean size and growth rates of Acacia trees and show that the density and biomass of arboreal geckos (Lygodactylus keniensis) are elevated near glades and decrease with distance from glades. The edge response of geckos is an indirect effect arising from the positive influence of glades on arboreal arthropod biomass (a trophic effect) and average tree size (a non‐trophic effect). By clearing plots of trees to simulate glades, we experimentally demonstrate that these legacy effects arise from the elevated nutrient content of glades as opposed to their distinctive structural features. Finally, we investigated interactions among glade edges, showing that legacy effects are dampened (rather than enhanced) by the presence of other glades nearby. Collectively, our results show that legacy effects of traditional pastoral practices cascade into the treetops, imparting spatial structure across multiple trophic levels in an otherwise homogeneous Kenyan savanna ecosystem.

Validation of non-pollen palynomorphs as paleoenvironmental indicators in tropical Africa: Contrasting ~ 200-year paleolimnological records of climate change and human impact

Multi-proxy investigation of high-resolution, ~200-year sediment records from two shallow, climate-sensitive crater lakes in western Uganda, surrounded by either presently undisturbed (Lake Chibwera) or severely disturbed (Lake Kanyamukali) catchments, provides insights into lake ecosystem and vegetation response to short-term natural climate variability, as separate from local human impact. Here, we present fossil non-pollen palynomorph (NPP) assemblages, mainly including spores of saprotrophic, coprophilous (dung-colonizing), and/or mycorrhizal fungi, to assess and validate their paleoecological significance in a tropical African context. At both sites, high abundances of the saprotrophic Coniochaeta spp. broadly coincide with documented decade-scale episodes of increased humidity (early- to mid-19th century, ~1870–1900AD and late 20th century). Severe drought in the late 18th and early 19th century reduced both lakes to ephemeral ponds, which were intensively visited by large wild and/or domestic herbivores, as indicated by abundant Sordaria spp. and Delitschia spp., obligately growing on herbivore dung. From the mid-19th century onwards, large herbivore presence at Chibwera declined, and remained low as the site became incorporated in a game reserve in the early 20th century, and was added to Queen Elizabeth National Park in 1965. In contrast, herbivore presence remained strong at Kanyamukali, where grazing and subsistence farming intensified from the mid-20th century onwards. The location of Lake Kanyamukali near an ancient cattle trail and/or trading route underscores its historical linkage with transhumance. Grazing activity at Kanyamukali is indicated mainly by slightly increased abundances of coprophilous Sordaria spp. and of Glomus sp., indicative of soil erosion. Only this modest change in the NPP assemblage can be uniquely attributed to relatively intense recent human impact at Kanyamukali, contrasting with the strong NPP response at both lakes to the shifts in large herbivore behavior associated with late 18th- and early 19th century climatic drought. Comparison of the two records therefore allows us to conclude that in African lakes, (i) only high densities of domestic large herbivores create a paleoenvironmental NPP signature that can be unambiguously linked to past pastoralist activity, and (ii) facultative coprophilous fungal spores are overwhelmingly controlled by natural, climate-driven fluctuations in the local availability of preferred substrates for the fungi.

Comparative changes in density and demography of large herbivores in the Masai Mara Reserve and its surrounding human-dominated pastoral ranches in Kenya

Wildlife habitats in pastoral lands adjoining protected areas in east African savannas are getting progressively degraded, fragmented and compressed by expanding human populations and intensification of land use. To understand the consequences of these influences on wildlife populations, we contrasted the density and demography of 13 wild and three domestic large herbivores between the Masai Mara National Reserve and the adjoining pastoral ranches using aerial surveys conducted in the wet and dry seasons during 1977–2010. Species of different body sizes and feeding styles had different densities between landscapes and seasons. Small-sized herbivores, requiring short, nutritious grasses, and browsers were more abundant in the ranches than the reserve in both seasons. Medium-sized herbivores moved seasonally between landscapes. Larger-bodied herbivores, requiring bulk forage but less susceptible to predation, were more abundant in the reserve than the ranches. The proportions of newborn warthog (Phacochoerus africanus) and juvenile topi (Damaliscus korrigum) were higher in the ranches, with shorter grasses and lower predation risk than in the reserve. These results suggest that pastoral lands adjoining protected areas in African savannas are important as seasonal dispersal and breeding grounds for wild herbivores. However, human population growth and dramatic land use changes are progressively degrading wildlife habitats in pastoral areas, thus restricting the seasonal wildlife dispersal movements between the protected areas and adjoining pastoral lands. Conservation efforts should focus on (1) creating and maintaining functional heterogeneity in protected areas that mimic moderate pastoral grazing conditions to attract small and medium-bodied grazers and (2) securing dispersal areas, including corridors, to ensure continued seasonal large herbivore movements between protected and pastoral systems.

Seed production in Polylepis australis (Rosaceae) as influenced by tree size, livestock and interannual climate variations in the mountains of central Argentina

The expansion of tree species within a grassland-woodland matrix relies heavily on an abundant seed crop, which may be affected by many factors; among these, browsing by livestock has gone largely ignored. Here we explore how seed production is affected by tree size, grazing by large domestic herbivores and interannual climate fluctuations in a small-sized tree (Polylepis australis, Rosaceae), which dominates the remnant forests in the high mountains of central Argentina. Seed number and seed mass per tree were quantified in 100 different-sized trees located in areas with and without livestock. Using seed traps we also determined seed rain variation in 15 plots between 2005 and 2008. The estimated number of seeds per tree ranged from 0 to 224,000 and increased with tree height (power relation); for trees smaller than 354 cm in height, seed production was lower in areas with livestock and higher in areas without livestock. Mass per seed increased with tree height, with no significant livestock effect. The largest seed rain was recorded in 2008, probably due to growth of seed trees and not in response to climate. To promote seed production and forest expansion, livestock should be excluded from areas with small trees, such as forest edges.

The fencing paradigm in woodland conservation: consequences for recruitment of a semi‐arid tree

AbstractQuestionHow does long‐term fencing against large domestic herbivores affect regeneration of the dominant tree, Prosopis flexuosa, and hence the structure of semi‐arid woodlands?LocationWoodlands in the Central Monte Desert biome of Argentina, Ñacuñán Man and the Biosphere Reserve area (34° 20′ S, 67° 58′ W) and surrounding cattle‐grazed ranches.MethodsWe compared seedling emergence and survival, the spatial distribution of seedlings and saplings, and the population stage‐based structure of P. flexuosa between paired sites inside and outside the Reserve of Ñacuñán (Argentina), which has been fenced to exclude domestic cattle for ca. 40 yr.ResultsReserve sites had lower tree recruitment and seedling emergence, in spite of having greater seed production and seedling survival. Outside the reserve, survival was higher for seedlings in high‐density clumps than for isolated seedlings. Seedling clumps occurred mostly near adult individuals, where cattle dung was abundant, suggesting an effect of cattle on seed dispersal. The balance between the effects of cattle exclusion on seedling emergence and on seedling survival was reflected in the stage structure of P. flexuosa woodlands, as populations at fenced sites were dominated by adult individuals, whereas those at cattle‐grazed areas presented greater proportions of seedlings and saplings.ConclusionFencing is a common practice used worldwide to exclude conservation areas from human disturbance. For example, it is assumed that disturbed woodlands may recover after fencing, thanks to increased tree recruitment after the exclusion of large herbivores. However, the actual effectiveness of fencing as a tool for forest conservation in overgrazed environments could be controversial because sequential effects of herbivores during the tree regeneration cycle may hamper predictions of the overall balance of the recruitment process. Our results suggest that dispersal by cattle influences the regeneration of P. flexuosa woodlands, and that the positive effects of cattle on seedling emergence compensate for the negative effects on seed production and seedling and sapling survival. Future management of P. flexuosa woodlands in the Central Monte Desert should consider that tree recruitment is closely related to land use, and that cattle exclusion does not necessarily guarantee woodland recovery in the long term.

Effects of corn steep liquor supplementation on voluntary selection of tallgrass prairie hay contaminated with sericea lespedeza and uncontaminated tallgrass prairie hay (2012)

Introduction Sericea lespedeza (Lespedeza cuneata) is classified as a noxious weed throughout the Great Plains. It produces copious amounts of seed annually and contains high levels of condensed tannins during much of the growing season, which deters grazing by large domestic herbivores. In Kansas alone, this plant infests approximately 600,000 acres of native range, reducing native grass production by up to 92%. Increased grazing pressure on sericea lespedeza by beef cattle may slow its spread and facilitate some measure of biological control. Feedstuffs or feed additives with tannin-binding properties may promote voluntary consumption of this plant by grazing beef cattle.

Co-occurrence and potential for competition between wild and domestic large herbivores in a South American desert

Introduction of domestic ungulates may lead to interspecific competition with native herbivores, particularly if the species involved are of similar size and share similar foraging strategies due to a scarcity of trophic resources. This interaction has not been investigated in South American deserts in which guanaco ( Lama guanicoe), the larger South American wild camelid and the most widely-distributed ungulate, co-occurs with several introduced ungulates (e.g. cattle, donkeys, sheep or red deer). We studied the occurrence and abundance patterns of guanacos, donkeys and cattle in desert areas of Argentina by dung sampling. Analyses of co-occurrence show no relationship in land use between guanaco and livestock when geographical effects are removed. Distribution and abundance models of the guanaco are strongly associated with sparse plant cover, rocky substrata and human-influence variables, guanacos appearing in areas furthest from villages. Nevertheless, while guanaco distribution is weakly related to feral livestock presence, their abundance is negatively associated with donkey presence. In contrast, livestock species appear closely associated with each other, being centred on areas of densest and most productive vegetation. These results are relevant for the management of extensive arid areas of South America, where guanacos co-occur with feral donkeys and frequently conflicts with humans activities.

How to use domestic large herbivores in restoring Europe’s threatened woodpasture landscapes?

How to use domestic large herbivores in restoring Europe’s threatened woodpasture landscapes?

Grazing-induced changes in plant species composition affect plant and soil properties of grassland mesocosms

Grazing-induced floristic changes in plant communities may accelerate or reduce plant and soil processes through changes in litter quality. Here, we intended to elucidate if the joint action of live and senescing plant tissue of palatable and non-palatable species differentially influences soil processes and properties. We conducted a 1-year experiment with mesocosms from a subhumid grassland. Mesocosms were monocultures of palatable or non-palatable species and a multispecific control. Palatable species included a legume and annual and perennial grasses, whereas non-palatable species included a perennial grass and annual and perennial forbs. Palatable monocultures showed greater soil mineral nitrogen, soil bacterial diversity, and lower soil pH than non-palatable monocultures. These differences were not accounted for by differences in plant biomass. The multispecific control treatment only exhibited greater shoot biomass than the monocultures, and lower root biomass than the palatable monocultures. Our results suggest that the whole (live + dead plant tissue) had a specific imprint on soil system even when variation was not very apparent in terms of plant biomass, and that this effect was associated with plant palatability to domestic large herbivores.

Impacts of large herbivorous mammals on bird diversity and abundance in an African savanna

Large native mammals are declining dramatically in abundance across Africa, with strong impacts on both plant and animal community dynamics. However, the net effects of this large-scale loss in megafauna are poorly understood because responses by several ecologically important groups have not been assessed. We used a large-scale, replicated exclusion experiment in Kenya to investigate the impacts of different guilds of native and domestic large herbivores on the diversity and abundance of birds over a 2-year period. The exclusion of large herbivorous native mammals, including zebras (Equus burchelli), giraffes (Giraffa camelopardalis), elephants (Loxodonta africana), and buffalos (Syncerus caffer), increased the diversity of birds by 30%. Most of this effect was attributable to the absence of elephants and giraffes; these megaherbivores reduced both the canopy area of subdominant woody vegetation and the biomass of ground-dwelling arthropods, and both of these factors were good predictors of the diversity of birds. The canopy area of subdominant trees was positively correlated with the diversity of granivorous birds. The biomass of ground-dwelling arthropods was positively correlated with the diversity of insectivorous birds. Our results suggest that most native large herbivores are compatible with an abundant and diverse bird fauna, as are cattle if they are at a relatively low stocking rate. Future research should focus on determining the spatial arrangements and densities of megaherbivores that will optimize both megaherbivore abundance and bird diversity.

Do domestic herbivores retard Polylepis australis Bitt. woodland recovery in the mountains of Córdoba, Argentina?

Herbivores are often an important factor hindering the recovery of woodlands. Browsing generally retards seedling and juvenile tree growth, but the exact impact of herbivores is still controversial. The high mountain areas of central Argentina consist of a mosaic of Polylepis australis Bitt. woodlands and different grassland types which are grazed by large domestic herbivores. To contribute to the management of these ecosystems, we performed an observational and an experimental study. In the first, we measured P. australis browsing intensity and size structure in areas with sparse woodland cover under two treatments. One treatment consisted of seven areas with high stocking rates, and the other consisted of five areas where livestock were reduced to low or moderate stocking rates 6–7 years prior to our measurements. In the experiment, we planted P. australis seedlings in a heavy grazed and an ungrazed area and measured growth and survival during 6 years. Our observational study showed that livestock browse heavily on P. australis, but a reduction of livestock densities reduced browsing rates and changed population size structure. The experimental results confirmed the high browsing rates, and showed that browsing negatively influences survival and height-growth. Our data suggests that heavy grazing by domestic herbivores retard P. australis woodland recovery, but a reduction in stocking rates promote changes that can lead to an increase in P. australis density. An adequate livestock management is therefore very important in the mountains of Córdoba.

Clinical Aspects of Rodent Dental Anatomy

The order Rodentia is vast, encompassing a large number of species with significant anatomical variations developed during natural adaptation to differing habitats. Many veterinarians have little knowledge of the anatomy of species other than the commoner domestic large herbivores and small carnivores. Clinicians require a basic knowledge of the relevant anatomy of species they are likely to be asked to treat. This article provides sufficient working knowledge of the oral and dental anatomy of those rodents commonly kept as pets to enable veterinarians to interpret clinical and radiographic findings when investigating suspected dental disease.

Buzzards Buteo buteo and land use in the new forest, Hampshire, England

The population ecology of buzzards Buteo buteo in the New Forest, southern England, was studied from 1961 to 1982. Until 1973 the population was relatively constant (32–37 pairs), though density and productivity were low compared with elsewhere in Britain, probably as a result of low densities of mammalian prey resulting from intensive grazing by free-ranging cattle and ponies. In 1973 there was a dramatic fall in productivity: only two pairs fledged young. Comparing 1962–1971 with 1973–1982, the average number of breeding attempts declined by 35%, the average number of succesful attempts by 44%, and the average number of young fledged by 40%. The number of occupied territories fell from 33 in 1974 to 21 in 1982 (a 36% decline). It is hypothesised that this was the result of further declines in numbers of small rodents caused by greatly increased grazing pressure by large domestic herbivores, and their penetration into hitherto ungrazed areas. The number of successful breeding attempts varied widely from year to year after 1973. From 1968 the number of successful breeding pairs of buzzards fluctuated in relation to the amount of tree and shrub seed produced the previous autumn, and we suggest that from the early 1970s buzzards responded positively to early spring numbers of small rodents, which were in turn related to seed abundance in the previous autumn. It seems likely that before 1973 population levels of small rodents were sufficiently high even after a poor seed year, to form the basis of the buzzards' food in early spring, which is believed to be a critical period, and that only when population levels were reduced further by habitat deterioration caused by increased grazing pressure did fluctuations become critical to buzzards. The implications of intensive grazing for other predators of small rodents, and the implications for the management of the New Forest are briefly reviewed.

The Structure and Function of Ten Western North American Grasslands: I. Abiotic and Vegetational Characteristics

(1) Data collected from coordinated comparative studies on the structure and function of ten central and western United States grasslands are presented and analysed. The ten study areas encompassed six major grassland types: mountain grassland, northwest bunchgrass, mixed-grass prairie, shortgrass prairie, tallgrass prairie and desert grassland. Experimental design at each location included two replications of ungrazed (i.e. long-term absence of grazing by large domestic herbivores) and grazed treatments. (2) Structural characteristics studied included quantities of cool- and warm-season plants at each site, and magnitude and seasonality of primary producer compartments. (3) The environmental variables measured at each site were precipitation, temperature and solar radiation. These variables were calculated as both annual and growing-season values, along with annual and growing-season potential and actual evapotranspiration. (4) The seasonal mean live biomass averaged 94 g m -2 for the ten grasslands, with a mean of 98 g m -2 on ungrazed grasslands and 89 g m -2 for grazed grasslands. Ungrazed grasslands averaged about 160 g m -2 of recent and old dead plant material, compared to approximately 70 g m -2 on grazed grasslands. Ungrazed grasslands had about 50 and 150% more recent and old dead material, respectively, than grazed grasslands. Generally, grazing in previous seasons decreased the standing crop of dead material across the grasslands. (5) The mean total shoot standing crop averaged 203 g m -2 for all grasslands across all treatments; ungrazed grasslands averaged 245 g m -2 , compared to 161 g m -2 for grazed grasslands. The magnitude of litter corresponded in general to the amount of total shoot standing crop. (6) Generally, the shortgrass prairie had the maximum amount of crown material, followed by the mixed-grass prairie, with the tallgrass prairie least. Crown material averaged c. 275 g m -2 for the mixed- and shortgrass prairie, compared to c. 200 g m -2 for the tallgrass prairie. Although grazing did not significantly influence the amount of crown material, crown material tended to increase under grazing in mixed-grass and shortgrass prairies. (7) Root biomass ranged from 156 g m -2 in the desert grassland to as much as 2000 g m -2 in the mixed-grass prairie, while other grasslands were intermediate between these two extremes. (8) There was an inverse relationship between root biomass and dynamics and mean annual temperature. Grazing generally resulted in an increase in the root/shoot ratios, particularly on the cooler grasslands.