Livestock Grazing Intensity Research Articles

Unexpectedly, intense livestock grazing in arid rangelands strengthens the seedling vigor of consumed plants

Grazing intensification with non-native livestock is known to degrade vegetation cover, particularly in arid environments where low resource availability strongly limits plant recovery after damage. However, it remains unclear whether the effect of grazing on consumed plants is transmitted to plant offspring. We hypothesized that grazing would reduce fruit weight, germination percentage, and seedling vigor of consumed vegetation. Therefore, we collected mature fruits from six dominant shrub species in seven independent paddocks with increasing livestock densities. Fruits were air-dried and weighed before seed sowing. After seedling emergence, we measured the percentage of germination and seedling vigor, i.e., height and number of leaves. Hierarchical models were used to account for the effects of plant species and year of collection. Results show that, in general, increasing livestock density reduced fruit weight and percentage of germination of consumed plants. However, surprisingly, increasing livestock density enhanced seedling vigor. Overall, increasing livestock density has both negative and positive effects on consumed plantsʼ offspring.

Functional diversity loss with increasing livestock grazing intensity in drylands: the mechanisms and their consequences depend on the taxa

SummaryOvergrazing is one of the main drivers of desertification in drylands, and livestock production is expected to increase in the next decades. The analysis of functional diversity can clarify the effects of increasing livestock grazing on ecosystem functioning.We assess the effect of livestock grazing intensity on the relationship between taxonomic diversity (TDH) and functional diversity (FDQ) of plants, ants and small mammals, as well as on within‐trait diversity. We compared results using two indices of taxonomic diversity (Shannon and Simpson indices). We used structural equation modelling (SEM) to assess the causal relationship between grazing intensity,TDH,FDQand decomposition rate for each taxa.Correlation betweenTDHvs.FDQvaried across assemblages and seasons, but was consistent between different indices of taxonomic diversity. A similar trajectory ofTDHvs.FDQunder land‐use intensification was found for all taxa, with a correlated loss of species and functional traits. Also, within‐trait diversity was negatively affected by increasing grazing pressure. Vegetation and small mammalSEMmodels show that increasing grazing intensity had a strong and direct effect on decomposition rate. The antSEMmodel was the only one that showed an indirect effect of grazing on decomposition throughFDQ.TDHhad no effect on decomposition for either taxa.We found higher niche differentiation in animal than in plant assemblages. In vegetation, several species seem to have similar trait diversity (i.e. redundancy), perhaps due to a dominant role of environmental constraints. These results were consistent among diversity indices. But increasing disturbance negatively affectedTDHvs.FDQin all assemblages in a similar way. Livestock grazing affected decomposition rate directly, and indirectly only through the effect of antFDQ.Synthesis and applications. Under increasing grazing intensity, all plant and animal assemblages respond with a mirrored reduction in taxonomic diversity and functional diversity, although vegetation seems to have higher functional redundancy. Our results are robust to diversity indices, and show that several taxa respond similarly to land‐use intensification, despite differences in the mechanism behind it. This may facilitate sustainable management. Notably, increasing grazing intensity affects decomposition rate through a stronger direct than indirect effect. The stronger direct effect of livestock on decomposition rate, rather than indirectly through functional diversity, suggests that changes in structure may be more important than changes in community composition.

Mapping Tree Canopy Cover in Support of Proactive Prairie Grouse Conservation in Western North America

Invasive woody plant expansion is a primary threat driving fragmentation and loss of sagebrush (Artemisia spp.) and prairie habitats across the central and western United States. Expansion of native woody plants, including conifer (primarily Juniperus spp.) and mesquite (Prosopis spp.), over the past century is primarily attributable to wildfire suppression, historic periods of intensive livestock grazing, and changes in climate. To guide successful conservation programs aimed at reducing top-down stressors, we mapped invasive woody plants at regional scales to evaluate landscape level impacts, target restoration actions, and monitor restoration outcomes. Our overarching goal was to produce seamless regional products across sociopolitical boundaries with resolution fine enough to depict the spatial extent and degree of woody plant invasion relevant to greater sage-grouse (Centrocercus urophasianus) and lesser prairie-chicken (Tympanuchus pallidicinctus) conservation efforts. We mapped tree canopy cover at 1-m spatial resolution across an 11-state region (508 265 km2). Greater than 90% of occupied lesser prairie-chicken habitat was largely treeless for conifers (<1% canopy cover), whereas > 67% was treeless for mesquite. Conifers in the higher canopy cover classes (16−50% and >50% canopy cover) were scarce (<2% and 1% canopy cover), as was mesquite (<5% and 1% canopy cover). Occupied habitat by sage-grouse was more variable but also had a relatively large proportion of treeless areas (x− = 71, SE = 5%). Low to moderate levels of conifer cover (1−20%) were fewer (x− = 23, SE = 5%) as were areas in the highest cover class (>50%; x− = 6, SE = 2%). Mapping indicated that a high proportion of invading woody plants are at a low to intermediate level. Canopy cover maps for conifer and mesquite resulting from this study provide the first and most geographically complete, high-resolution assessment of woody plant cover as a top-down threat to western sage-steppe and prairie ecosystems.

Multiscale perspectives of fire, climate and humans in western North America and the Jemez Mountains, USA.

Interannual climate variations have been important drivers of wildfire occurrence in ponderosa pine forests across western North America for at least 400 years, but at finer scales of mountain ranges and landscapes human land uses sometimes over-rode climate influences. We reconstruct and analyse effects of high human population densities in forests of the Jemez Mountains, New Mexico from ca 1300 CE to Present. Prior to the 1680 Pueblo Revolt, human land uses reduced the occurrence of widespread fires while simultaneously adding more ignitions resulting in many small-extent fires. During the 18th and 19th centuries, wet/dry oscillations and their effects on fuels dynamics controlled widespread fire occurrence. In the late 19th century, intensive livestock grazing disrupted fuels continuity and fire spread and then active fire suppression maintained the absence of widespread surface fires during most of the 20th century. The abundance and continuity of fuels is the most important controlling variable in fire regimes of these semi-arid forests. Reduction of widespread fires owing to reduction of fuel continuity emerges as a hallmark of extensive human impacts on past forests and fire regimes.This article is part of the themed issue ‘The interaction of fire and mankind’.

Carbon budgets for an irrigated intensively grazed dairy pasture and an unirrigated winter-grazed pasture

Abstract. Intensification of pastoral agriculture is occurring rapidly across New Zealand, including increasing use of irrigation and fertiliser application in some regions. While this enables greater gross primary production (GPP) and livestock grazing intensity, the consequences for the net ecosystem carbon budget (NECB) of the pastures are poorly known. Here, we determined the NECB over one year for an irrigated, fertilised and rotationally grazed dairy pasture and a neighbouring unirrigated, unfertilised, winter-grazed pasture. Primary terms in the NECB calculation were: net ecosystem production (NEP), biomass carbon removed by grazing cows and carbon (C) input from their excreta. Annual NEP was measured using the eddy-covariance method. Carbon removal was estimated with plate-meter measurements calibrated against biomass collections, pre- and post-grazing. Excreta deposition was calculated from animal feed intake. The intensively managed pasture gained C (NECB = 103 ± 42 g C m−2 yr−1) but would have been subject to a non-significant C loss if cattle excreta had not been returned to the pasture. The unirrigated pasture was C-neutral (NECB = −13 ± 23 g C m−2 yr−1). While annual GPP of the former was almost twice that of the latter (2679 vs. 1372 g C m−2 yr−1), ecosystem respiration differed by only 68 % between the two pastures (2271 vs. 1352 g C m−2 yr−1). The ratio of GPP to the total annual water input of the irrigated pasture was 37 % greater than that of the unirrigated pasture, i.e. the former used the water input more efficiently than the latter to produce biomass. The NECB results agree qualitatively with those from many other eddy-covariance studies of grazed grasslands, but they seem to be at odds with long-term carbon-stock studies of other New Zealand pastures.

Influence of land sharing and land sparing strategies on patterns of vegetation and terrestrial vertebrate richness and occurrence in Australian endangered eucalypt woodlands

Native vegetation placed under an agri-environment scheme (AES) is purported to support greater biodiversity than vegetation managed for intensive livestock grazing, and conservation reserves are purported to support greater biodiversity than land sharing under AES. These predictions underpin financial incentive delivery programs that enable landholders to adopt environmentally friendly agricultural practices. To evaluate these predictions, we established a biodiversity monitoring program in endangered temperate eucalypt woodland communities in southern Australia. We compared vegetation variables and vertebrate species richness and abundance among sites under different land management between 2010 and 2014. Our sites included: (1) woodland remnants on private property recently placed under an AES land management agreement (land sharing), (2) woodland remnants in State conservation reserves as reference areas (land sparing), and (3) woodland remnants used for intensive livestock production as controls. We used hierarchical generalized linear models to examine patterns of biodiversity among management classes and over time. We found conservation reserves were structurally more complex and floristically richer compared to production sites, and AES supported greater cover of native perennial grass. Reptile and amphibian species richness and abundance, and total bird species richness did not differ significantly among management classes, although AES and reference sites supported more birds of conservation concern. Arboreal marsupials were significantly more species rich in conservation reserves than AES. Temporal patterns in vertebrate species richness were related to post-drought climatic conditions. Our findings suggest that strategies involving land sharing under AES are as effective as land sparing (e.g. conservation reserves) for bird conservation, but alternative strategies may be required to enhance habitat for less mobile species such as frogs and reptiles, or species dependant on old growth vegetation such as arboreal marsupials.

Simple Approaches to Improve Restoration of Coastal Sage Scrub Habitat in Southern California

ABSTRACT Much of the coastal sage scrub habitat in Southern California that existed prior to European settlement has been developed for human uses. Over the past two to three decades, public agencies and land conservation organizations have worked to acquire some of the remaining lands for preservation. Many of these lands are degraded by past intensive livestock grazing, farming, and frequent fires, and the native flora has been replaced by weedy, exotic annual grasses and forbs, mostly of Mediterranean origin. Restoration of native flora is challenging and there are few successful examples to provide guidance on effective methods. Cost is also an important and prohibitive factor. Competition from weeds is one of the most difficult impediments to establishing native vegetation, which often persists in the seedbank. We compared annual applications of the nonselective herbicide glyphosate over multiple years, followed by a final year with the grass-specific fluazifop, as a simple, low cost method of reduci...

Rodents in grassland habitats: does livestock grazing matter? A comparison of two Alpine sites with different grazing histories

ABSTRACT Intensive livestock grazing is a major force in shaping ecosystems, especially where topography and soil features preclude other farmland practices. In subalpine landscapes, it may be the main disturbance agent. Nevertheless, information on the impact on some species, especially mammals, is lacking. Here, we investigate whether the abundance of rodents in subalpine grasslands of the Alps is related to the intensity of livestock grazing, determined according to the dominant pastoral types. Using Generalized Linear Models, we compared a site intensively grazed until recently (“formerly intensively grazed area”, Dactylis glomerata L. pastoral type), with an area that experienced little or no grazing in past decades (“lightly grazed area”, Carex sempervirens Vill. pastoral type). Data were collected during three trapping sessions during summer 2011, using a sampling design based on small trapping plots. Rodents (Apodemus spp. and Eliomys quercinus Linnaeus, 1766) were mainly trapped in the lightly gr...

Floristic and structural patterns in South Brazilian coastal grasslands.

The natural vegetation of Southern Brazil's coastal region includes grasslands formations that are poorly considered in conservation policy, due to the lack of knowledge about these systems. This study reports results from a regional-scale survey of coastal grasslands vegetation along a 536 km gradient on southern Brazil. We sampled 16 sites along the coastal plain with 15 plots (1 m²) per site. All sites were grazed by cattle. We estimated plant species cover, vegetation height, percentage of bare soil, litter and manure, and classified species according to their growth forms. We found 221 species, 14 of them exotic and two threatened. The prostate grasses: Axonopus aff.affinis, Paspalum notatum and P. pumilumwere among the most important species. Prostrate graminoids species represented the most important vegetation cover, followed by cespitose grasses. Vegetation height, bare soil, litter and manure were similar among all areas, highlighting the homogeneity of sampling sites due to similar management. In comparison to other grasslands formations in Southern Brazil, the coastal grasslands presented rather low species richness. The presence of high values for bare soil at all sampling sites indicates the need to discuss management practices in the region, especially with regard to the intensity of livestock grazing.

Soil aggregate stability was an uncertain predictor of ecosystem functioning in a temperate and semiarid grassland

We estimate rangeland managers assessing ecosystem health have measured soil stability &gt;800,000 times. Our aim was to use quantitative data from a site in the Northern Great Plains, USA and a semi‐quantitative literature search to demonstrate the robustness of soil stability as an indicator of ecosystem functioning. Empirical data included measurements of plant and soil properties along a local livestock grazing gradient to determine whether soil stability (e.g., % water‐stable aggregates) explained primary productivity and soil water transport for a mixed‐grass prairie site in the Northern Great Plains. We measured: annual net primary productivity (ANPP), elevation, % soil moisture, measures of soil stability, and soil water transport (field‐saturated infiltrability and sorptivity) across points spanning a local gradient in livestock grazing intensity (none vs. light to moderate stocking rates; mean distance separating points = 39.9 m [range = 5.2–71.3 m]). Across the sampled gradient, variation in ANPP was best explained by a model with field‐saturated infiltrability and % soil moisture. Infiltrability explained slightly more of the variation. We then determined that moderate amounts of variation in infiltrability were explained by ANPP, % soil moisture, and % water‐stable aggregates. We determined that most of this variation was explained by ANPP and then soil moisture. Our empirical findings indicate that plant production was correlated with infiltration though we could not determine whether variation in plant production was caused by variation in infiltration or vice versa. We generally failed to show that soil stability (e.g., % water‐stable aggregates) was a useful predictor of primary productivity and soil water transport. Our semi‐quantitative literature review also indicated that soil stability was not a consistent predictor of either plant production or infiltration. The varying evidence reported here on whether soil stability is a predictor of ecosystem function illustrates the difficulty in identifying an indicator of ecosystem health that (1) is a predictor of ecosystem function across grassland types, (2) is sensitive to rangeland management, and (3) can be easily implemented by non‐experts.

Environmental Quality and Aquatic Invertebrate Metrics Relationships at Patagonian Wetlands Subjected to Livestock Grazing Pressures.

Livestock grazing can compromise the biotic integrity and health of wetlands, especially in remotes areas like Patagonia, which provide habitat for several endemic terrestrial and aquatic species. Understanding the effects of these land use practices on invertebrate communities can help prevent the deterioration of wetlands and provide insights for restoration. In this contribution, we assessed the responses of 36 metrics based on the structural and functional attributes of invertebrates (130 taxa) at 30 Patagonian wetlands that were subject to different levels of livestock grazing intensity. These levels were categorized as low, medium and high based on eight features (livestock stock densities plus seven wetland measurements). Significant changes in environmental features were detected across the gradient of wetlands, mainly related to pH, conductivity, and nutrient values. Regardless of rainfall gradient, symptoms of eutrophication were remarkable at some highly disturbed sites. Seven invertebrate metrics consistently and accurately responded to livestock grazing on wetlands. All of them were negatively related to increased levels of grazing disturbance, with the number of insect families appearing as the most robust measure. A multivariate approach (RDA) revealed that invertebrate metrics were significantly affected by environmental variables related to water quality: in particular, pH, conductivity, dissolved oxygen, nutrient concentrations, and the richness and coverage of aquatic plants. Our results suggest that the seven aforementioned metrics could be used to assess ecological quality in the arid and semi-arid wetlands of Patagonia, helping to ensure the creation of protected areas and their associated ecological services.

Moderate livestock grazing of salt, and brackish marshes benefits breeding birds along the mainland coast of the Wadden Sea

ABSTRACT Our study investigated how bird species richness and abundance was related to livestock grazing on salt, and brackish marshes, with an emphasis on songbirds, and shorebirds. Survey areas with a high percentage cover of tall vegetation were assumed to have experienced lower livestock grazing intensities than survey areas with a low percentage cover of tall vegetation. This relationship was verified for the tall grass Elytrigia atherica. The species richness, and abundance of birds was related to the percentage cover of tall vegetation on the survey areas. We found that total bird species richness was positively related to the percentage cover of tall vegetation. We also found that all of the investigated species, except Pied Avocet (Recurvirostra avosetta), showed a positive relation to the percentage cover of tall vegetation up to a specific percentage of cover. The abundance of investigated songbird species increased up to an intermediate percentage cover of tall vegetation, and decreased at hig...

Persistence at distributional edges: Columbia spotted frog habitat in the arid Great Basin, USA.

A common challenge in the conservation of broadly distributed, yet imperiled species is understanding which factors facilitate persistence at distributional edges, locations where populations are often vulnerable to extirpation due to changes in climate, land use, or distributions of other species. For Columbia spotted frogs (Rana luteiventris) in the Great Basin (USA), a genetically distinct population segment of conservation concern, we approached this problem by examining (1) landscape-scale habitat availability and distribution, (2) water body-scale habitat associations, and (3) resource management-identified threats to persistence. We found that areas with perennial aquatic habitat and suitable climate are extremely limited in the southern portion of the species’ range. Within these suitable areas, native and non-native predators (trout and American bullfrogs [Lithobates catesbeianus]) are widespread and may further limit habitat availability in upper- and lower-elevation areas, respectively. At the water body scale, spotted frog occupancy was associated with deeper sites containing abundant emergent vegetation and nontrout fish species. Streams with American beaver (Castor canadensis) frequently had these structural characteristics and were significantly more likely to be occupied than ponds, lakes, streams without beaver, or streams with inactive beaver ponds, highlighting the importance of active manipulation of stream environments by beaver. Native and non-native trout reduced the likelihood of spotted frog occupancy, especially where emergent vegetation cover was sparse. Intensive livestock grazing, low aquatic connectivity, and ephemeral hydroperiods were also negatively associated with spotted frog occupancy. We conclude that persistence of this species at the arid end of its range has been largely facilitated by habitat stability (i.e., permanent hydroperiod), connectivity, predator-free refugia, and a commensalistic interaction with an ecosystem engineer. Beaver-induced changes to habitat quality, stability, and connectivity may increase spotted frog population resistance and resilience to seasonal drought, grazing, non-native predators, and climate change, factors which threaten local or regional persistence.

Soil properties along a gradient from hillslopes to the savanna plains in the Lambwe Valley, Kenya

Changes in land use and management strongly affect the physical and chemical properties of soils and their ecological functions. Especially, regions in East Africa have experienced dramatic land use changes in the past, but the spatial variability of soil properties and the impacts associated with those changes have been rarely documented. We investigated changes of major soil physical and chemical parameters along a gradient from hillslopes covered with forest and pasture, to the plains dominated by agriculture and savanna grassland in the upper Lambwe Valley in western Kenya. Additionally, we analyzed soil properties within a fenced area on the hillslopes in order to identify potential soil recovery effects after the exclusion of livestock grazing. We showed that topography, geological background, and soil formation processes were the primary controlling factors for variations in soil depth, the amount of rock fragments, and the textural composition of the soils. Agricultural cultivation strongly increased bulk densities and reduced hydraulic conductivity and plant available water capacity due to tillage-induced subsoil compaction. Intensive livestock grazing also increased bulk densities and negatively affected hydraulic properties although less strongly pronounced than the impacts of agricultural cultivation. Carbon and nitrogen levels were significantly lower in farmed and pasture soils compared to the forested hillslopes. For the exclusion of grazing, however, we did not observe significant differences in soil physical and chemical parameters as fencing has been maintained for few years only and natural soil recovery is a long-term process. This study provides quantitative information on the spatial distribution and variability of soil properties associated with different land use and management systems in the upper Lambwe Valley and will be of use for future research on ecosystem processes in this region. However, additional soil survey campaigns will be required to create a complete picture of the soil landscape for the entire area of the Lambwe Valley.

Effects of different management regimes on soil erosion and surface runoff in semi-arid to sub-humid rangelands

Over one billion people's livelihoods depend on dry rangelands through livestock grazing and agriculture. Livestock grazing and other management activities can cause soil erosion, increase surface runoff and reduce water availability. We studied the effects of different management regimes on soil erosion and surface runoff in semi-arid to sub-humid rangelands. Eleven management regimes were assessed, which reflected different livestock grazing intensities and rangeland conservation strategies. Our review yielded key indicators for quantifying soil erosion and surface runoff. The values of these indicators were compared between management regimes. Mean annual soil loss values in the ‘natural ungrazed’, ‘low intensity grazed’, ‘high intensity grazed rangelands’ and ‘man-made pastures’ regimes were, respectively, 717 (SE = 388), 1370 (648), 4048 (1517) and 4249 (1529) kg ha−1 yr−1. Mean surface runoff values for the same regimes were 98 (42), 170 (43), 505 (113) and 919 (267) m3 ha−1 yr−1, respectively. Soil loss and runoff decreased with decreasing canopy cover and increased with increasing slope. Further analyses suggest that livestock grazing abandonment and ‘exotic plantations’ reduce soil loss and runoff. Our findings show that soil erosion and surface runoff differ per management regime, and that conserving and restoring vulnerable semi-arid and sub-humid rangelands can reduce the risks of degradation.

Do shrubs reduce the adverse effects of grazing on soil properties?

AbstractIncreases in the density of woody plants are a global phenomenon in drylands, and large aggregations of shrubs, in particular, are regarded as being indicative of dysfunctional ecosystems. There is increasing evidence that overgrazing by livestock reduces ecosystem functions in shrublands, but that shrubs may buffer the negative effects of increasing grazing. We examined changes in water infiltration and nutrient concentrations in soils under shrubs and in their interspaces in shrublands in eastern Australia that varied in the intensity of livestock grazing. We used structural equation modelling to test whether shrubs might reduce the negative effects of overgrazing on infiltration and soil carbon and nitrogen (henceforth ‘soil nutrients’). Soils under shrubs and subject to low levels of grazing were more stable and had greater levels of soil nutrients. Shrubs had a direct positive effect on soil nutrients; but, grazing negatively affected nutrients by increasing soil bulk density. Structural equation modelling showed that shrubs had a direct positive effect on water flow under ponded conditions but also enhanced water flow, indirectly, through increased litter cover. Any positive effects of shrubs on water flow under low levels of grazing waned at high levels of grazing. Our results indicate that shrubs may reduce the adverse effects of grazing on soil properties. Specifically, shrubs could restrict access to livestock and therefore protect soils and plants beneath their canopies. Low levels of grazing are likely to ensure the retention of soil water and soil carbon and nitrogen in shrubland soils. Copyright © 2015 John Wiley &amp; Sons, Ltd.

Forest structure and fuels dynamics following ponderosa pine restoration treatments, White Mountains, Arizona, USA

Southwestern ponderosa pine forest ecosystems have become uncharacteristically dense as a result of intensive livestock grazing, logging, and fire exclusion, which have contributed to a buildup of fuels and increased vulnerability to high-severity, landscape-scale crown fires. In 2002, we implemented a replicated ecological restoration experiment to (1) quantify site-specific reference conditions, (2) analyze effects of elevation on forest structure, surface fuels, and canopy fuels, (3) test responses to three treatments: control, full treatment, and burn-only, and (4) evaluate effectiveness of treatments for restoring attributes to near historical reference conditions. Reconstructed reference conditions showed that basal area (BA) averaged 9.2m2ha−1 and tree density averaged 86.2treesha−1 across the site in 1880 prior to widespread fire exclusion, with the highest tree density values occurring at the two upper elevation sites. In 2002, prior to treatment, BA averaged 28.9m2ha−1 and density averaged 927.9treesha−1, representing three- and ten-fold increases, respectively, compared to 1880 values with a higher proportion of the increase coming from mesic species at higher elevations. By 2013 (5-years post-treatment), the full treatment showed BA was reduced by 52% compared to pre-treatment values from 31m2ha−1 to 15m2ha−1 and density was reduced by 85% from 998treesha−1 to 153treesha−1. In the burn-only treatment, BA increased by 6% from 27.5m2ha−1 to 29.1m2ha−1 although density was reduced by 25% from 837treesha−1 to 625treesha−1 between 2002 and 2013. Canopy fuels dynamics were similar to forest structure responses: low values prior to fire exclusion, a marked increase by the pre-treatment measurement, substantial reductions following thinning plus burning, and minor reductions following burn-only treatments. Post-treatment diameter distributions in the full treatment closely resembled reference conditions; minor reductions occurred in the lower diameter classes in the burn-only. Mortality of trees established before European settlement circa 1880 varied by treatment: 25% of presettlement trees alive in 2002 died by 2013 in the full treatment, 31% died in the burn-only treatment, and 15% died in the control. Of the treatments tested, the full treatment was the only one that rapidly shifted forest structure, diameter distributions, and canopy fuels values to levels near or within the historical reference conditions. Results from this study showed that managers will have to consider tradeoffs between alternative treatments in the context of climate-induced, landscape-scale forest fires.

Assessment of biotic and abiotic factors controlling herbaceous biodiversity in Mongolian steppes

Spatial patterns of herbaceous biodiversity in Mongolia steppe were examined and explained with biotic and abiotic factors including climate, livestock grazing, and fire disturbance. Vegetation data were collected from 63 sites across different steppe types (i.e., semi-desert, typical, and forb steppes) in 2012 and 2013. Three categorical (three steppe types, burned or not, grazed or not) and three continuous variables (precipitation, vegetation productivity, site-camp distance) were developed from national climate and GIS database of Mongolia and two satellite sensor products: Tropical Rainfall Measuring Mission (TRMM) precipitation and June-to-August accumulated Moderate Resolution Imaging Spectroradiometer (MODIS) Normalized Difference Vegetation Index (NDVIJJA). The prescribed factors were utilized to examine single- and multiple-factor effects on biodiversity and community structure, by using correlation, stepwise multiple regression analysis, and ordination. Our results indicate the positive effect of precipitation and fire but negative effect of grazing on biodiversity in our study region. Localized herding effect was recognized to areas less than 1.5km away from the herder's camp sites. Fire, precipitation and productivity (NDVIJJA) were identified as important factors affecting biodiversity of remote regions. Based on the results, we infer that pastureland biodiversity of Mongolia is controlled by region-scale variations of climate and vegetation productivity, but locally modified by intensive livestock grazing pressure with different grazing sensitivity for different steppe types.

Mapping and modelling trade-offs and synergies between grazing intensity and ecosystem services in rangelands using global-scale datasets and models

Vast areas of rangelands across the world are grazed with increasing intensity, but interactions between livestock production, biodiversity and other ecosystem services are poorly studied. This study explicitly determines trade-offs and synergies between ecosystem services and livestock grazing intensity on rangelands. Grazing intensity and its effects on forage utilization by livestock, carbon sequestration, erosion prevention and biodiversity are quantified and mapped, using global datasets and models. Results show that on average 4% of the biomass produced annually is consumed by livestock. On average, erosion prevention is 10% lower in areas with a high grazing intensity compared to areas with a low grazing intensity, whereas carbon emissions are more than four times higher under high grazing intensity compared to low grazing intensity. Rangelands with the highest grazing intensity are located in the Sahel, Pakistan, West India, Middle East, North Africa and parts of Brazil. These high grazing intensities result in carbon emissions, low biodiversity values, low capacity for erosion prevention and unsustainable forage utilization. Although the applied models simplify the processes of ecosystem service supply, our study provides a global overview of the consequences of grazing for biodiversity and ecosystem services. The expected increasing future demand for livestock products likely increase pressures on rangelands. Global-scale models can help to identify targets and target areas for international policies aiming at sustainable future use of these rangelands.

Human-derived landscape changes on the northern Etruria coast (western Italy) between Roman times and the late Middle Ages

Anthracological analysis has been carried out in three sites located on the Tyrrhenian coast of central Italy (ancient northern Etruria: the castle of Donoratico, the town of Populonia and the port of Alberese), spanning between the Roman Republican Period and the Late Middle Ages (3rd century bc–13th century ad). The integrated comparison of three different local charcoal data with the regional pollen and microcharcoal data available from northern Etruria showed well that vegetation changes are completely independent of climate and strictly connected to economic and social dynamics characterising the history of this part of central Italy. Indeed, Quercus ilex forests progressively retracted from the 3rd century bc in favour of open macchia formations just during the growing human impact of the Romanisation when intensive agriculture and livestock grazing characterised the economic system. The transition from macchia to deciduous Quercus forest at the end of the Roman Period from the mid-4th to the mid-5th centuries ad and long lasting until the 9th–10th centuries ad was related to economic and cultural factors which led to a phase of land abandonment. Finally, between the 11th and 13th centuries ad, the vegetation cover shifted again towards an open macchia environment at the same time of a re-settlement phase well evidenced also by intensive orcharding. Charcoal data also showed that the expansion of olive and chestnut in central Italy only began in the Late Medieval Period (11th century ad) and not in the Roman Period. This means that extensive cultivation of chestnut and olive has very recent origins and should be attributed to one and the same macro-factor such as the set-up of the economic establishment of the feudal system and the later political organism of the Medieval town.