Domestic Grazing Research Articles

Comparative Analysis of Gut Bacterial Diversity in Wild and Domestic Yaks on the Qinghai-Tibetan Plateau.

The gut microbiota is a diverse and complex population, and it has a key role in the host's health and adaptability to the environment. The present study investigated the fecal bacterial community of wild grazing (WG) and domestic grazing (DG) yaks on natural grazing pastures, analyzing the gut microbiota using 16S rRNA sequencing to assess bacterial diversity. A total of 48 yak fecal samples were selected from two different grazing habitats. The DG group had more crude proteins and non-fiber carbohydrates. The WG group had more OM, insoluble dietary fiber such as NDF, ADF, ether extract, and TC. There were 165 and 142 unique operational taxonomic units (OTUs) in the WG and DG groups, respectively. Shannon index analysis revealed a higher bacterial diversity in the WG group than in the DG group. At the phylum level, Firmicutes were the dominant bacterial taxa in both groups. The relative abundance of Firmicutes in the WG group was higher than in the DG group. At the family level, the WG group had a significantly higher abundance of Ruminococcaceae (p < 0.001) and Rikenellaceae (p < 0.001) than the DG group. The abundances of Alloprevotella and Succinivibrio were more pronounced in the DG group than in the WG group at the genus level. This study presents a novel understanding of the bacterial communities of ruminants and their potential applications for livestock production.

Herbivory baseline estimates in Spanish protected areas, and environmental implications

ContextThere are no estimations of herbivory baselines in Spain. Due to the bioclimatic conditions, ungulates have maintained Open Ecosystems until the Holocene. Pastoral tradition later fulfilled the niche of wild grazers, but this role is not considered in environmental assessments of grazing livestock.ObjectivesWe attempted to better understand the scale of herbivory in Spain. We aimed to estimate the weight of current wild herbivory and evaluate the role of domestic herbivory in these baselines. We applied them to improve the allocation of environmental impacts and emissions from grazing livestock.MethodsWe inferred an equation relating Net Primary Productivity (NPP) with ungulate biomass and enteric CH4 with data from 11 Spanish Protected Areas. We estimated theoretical baselines in Spain using other literature sources. We applied the equations to the Spanish open ecosystems that are currently grazable. We also estimated the proportion of grazing livestock that would be part of such baseline.ResultsWe found relationships between NPP and ungulate biomass and enteric CH4 emissions. However, current abundances are several times below the estimated baselines and the carrying capacity. There are major constraints for herbivore populations to reach their baseline state, particularly the absence of migration and the extinction of grazers among wild herbivores. Structural maintenance of Open Ecosystems should therefore be complemented by domestic grazers that cannot be replaced by the extant wild, mostly browser, ungulates.ConclusionsWe concluded that Spain is widely susceptible to being populated by herbivores that generate Open Ecosystems as baseline landscapes. Current grazing livestock accounts for a significant part of them, so baselines must be included in their environmental assessments. For the case of Spain, we propose a minimum baseline equivalent to 36% of current grazing livestock biomass and 23% of their enteric CH4 emissions.

Grazing intensity drives a trophic shift in the diet of common alpine birds

Large mammalian herbivores (LMH) shape vertebrate communities and structure food webs in many terrestrial ecosystems. However, the mechanisms that underlie the effects of LMH on other vertebrates are poorly understood. In France, domestic LMH have grazed alpine and mountain grasslands for thousands of years, profoundly influencing landscapes and wildlife. As LMH modify habitat structure, favour coprophagous insects and compete with herbivorous insects, the diet of insectivorous alpine birds may be deeply influenced by LMH grazing intensity. To investigate this, we sampled common insectivorous birds faeces (water pipit Anthus spinoletta and wheatear Oenanthe oenanthe) in sites characterized by different levels of grazing intensity by domestic and wild herbivores, in the open landscapes of the southern French Alps and the western Pyrenees. We used isotopic discrimination based on nitrogen stable isotope ratios as an indicator of the trophic level of the arthropods found in bird faeces. From isotopic ratios, we found that bird diets shift from mainly herbivorous arthropods at sites of low grazing intensity, to one mainly composed of other groups, such as predatory, detritivorous or coprophagous arthropods, at sites of higher grazing intensity. This result highlights the strong trophic link between LMH and insectivorous birds in open landscapes, contributing to a better understanding of interactions between domestic grazing, an activity that has historically modelled European landscapes, and biodiversity, with particular relevance for landscape management and bird conservation.

Coexistence of grasses and shrubs in Patagonian steppes. Norm or exception?

AbstractQuestions(1) Is the co‐dominance of grasses and shrubs a general feature of Patagonian steppes? (2) At a local scale, does it change with domestic grazing intensity or decadal changes in precipitation?LocationsQuestion 1. Patagonia region in southern South America. Question 2. Shrub–grass steppes (45°24′S, 70°17′W) subjected to different grazing intensity for decades.MethodsWe sampled vegetation to estimate perennial grass and shrub cover at two scales: regional and local. At the regional (phytogeographical) scale, we sampled grazed steppes under different climates and soils (n = 324 sites over ca. 487,000 km2). At the local scale, we sampled paddocks subjected to known grazing management, from commercial intensive densities of sheep to total (experimental) exclusion. Also, in the same site, we sampled permanent plots (25 years old) in a grazing exclosure to study the effects of precipitation variation.ResultsMixed communities are the predominant form of community organization in the Patagonia region. At the regional scale, shrub cover was negatively related to grass cover and communities where shrubs had higher cover than grasses represent 54% of the data set. At the local scale for an arid steppe, perennial grasses had higher cover than shrubs, regardless of grazing pressure. The shrub‐to‐grass ratio was increased only by intensive grazing. Permanent plots in a grazing‐excluded paddock indicate that decadal xeric or humid climate periods decrease or increase total cover, respectively. Surprisingly, the relative shrub‐to‐grass ratio did not change significantly.ConclusionsAlthough perennial grasses and shrubs cover are negatively correlated, they coexist in the Patagonian steppes under a wide range of climate, soil and grazing conditions. At a local scale, selective herbivory promotes species replacement but did not substantially change the life‐form covers. Water shortages, as well as periods of water surplus, similarly affect both life forms without compromising their coexistence.

Population development and landscape preference of reintroduced wild ungulates: successful rewilding in Southern Italy.

In the past decades, the abandonment of traditional land use practices has determined landscape changes inducing reforestation dynamics. This phenomenon can be contrasted with rewilding practices, i.e., the reintroduction of animals that may promote the recovery of landscape diversity. In this study, we explore the dynamics of expansion of two reintroduced populations of wild ungulates, Italian roe deer (Capreolus capreolus italicus) and red deer (Cervus elaphus), assessing their contribution in the recovery of landscape diversity. By using direct and indirect information on the two species, collected by nocturnal and diurnal surveys and camera trapping, we modelled a habitat suitability map, and estimated the density and distribution of the populations. We also performed a land use changes analysis, combining the presence of wild ungulates and livestock. We demonstrated that deer dispersed gradually from their release location, increasing in population size, and this occurred in the entire study area. Moreover, we show that areas with lower grazing density are significantly affected by forest encroachment. A possible interpretation of this result could be that wild grazers (roe deer and red deer) prefer semi-open areas surrounded by the forest. This, in association with other factors, such as domestic grazing, could be one of the main responsible in maintaining landscape mosaic typical of the Apennine mountain, confirming the value of grazers as a landscape management tool. Moreover, we show the possibility to conserve through reintroduction the vulnerable C.c. italicus.

Composición florística y funcional del pastizal natural del centro de la Argentina: Efecto del pastoreo bovino y el fuego

The state and conservation of the natural resources involved in production systems is of global concern. In Argentina, the expansion of the agricultural frontier from the Humid Pampa to the west has intensified livestock activity in semi-arid areas, decreasing the probability of finding sites that are not severely anthropized for productive purposes. The objectives of this work were to characterize the floristic and functional composition of the herbaceous stratum of caldén forests in a site excluded from domestic grazing in the last 50 years and to compare it with two other situations: one, with a winter fire event and subsequent exclusion of ca

Lower food intake due to domestic grazing reduces colony size and worsens the body condition of reproductive females of harvester ants

Lower food intake due to domestic grazing reduces colony size and worsens the body condition of reproductive females of harvester ants

Controlling trapping, overgrazing and invasive vegetation is key to saving Java’s last population of the Black-winged Myna

AbstractThe Black-winged Myna (Acridotheres melanopterus) is an Endangered passerine endemic to the islands of Java and Bali, Indonesia. Illegal trapping to supply the cage-bird trade has led to its near-total extinction, with the global population estimated to number fewer than 100 individuals. We estimated the current range and population size of the species at Baluran National Park, which supports Java’s last known population, and used species distribution modeling to evaluate potential suitability of currently unoccupied areas across the park to identify priorities for management intervention. We estimate that the Black-winged Myna population numbers 179 individuals (95% CI: 111–288; density: 14.3 ± 3.5 individuals km–2) and that its current range is 12.3 km2. Our model indicated that some 72 km2 of the park (30% of total area) has potentially suitable habitat for the species, and we infer that the principal cause for the disparity between its current and potential range is trapping, compounded by savanna loss and degradation due to illegal domestic cattle grazing and the spread of invasive thorny acacia (Vachellia nilotica). The partial clearance of acacia in recent years appears to have assisted a modest population recovery by the myna. Its further population growth and range expansion in Baluran will depend on effective management of illegal poaching, further clearance of acacia, and easing domestic cattle grazing pressure on areas of savanna, particularly through engagement with communities living inside the park. Any actions that increase the size of the Black-winged Myna population are likely to benefit other threatened savanna-dependent wildlife in the park, notably banteng (Bos javanicus) and Green Peafowl (Pavo muticus). While our models and recommendations may be applicable to other protected areas in Java, and indeed other threatened myna species, trapping and habitat change may have site-specific dimensions, especially outside of protected areas, and thus demand local bespoke solutions.

Contrasting effects of grazing on the early stages of woody encroachment in a Neotropical savanna

Woody encroachment in savannas represents an ecological process of current global interest given its negative impact on ecosystem functioning, particularly on forage production. Traditional savanna models propose competition and niche differentiation as the main mechanisms allowing tree-grass coexistence. Demographic models, instead, propose abiotic and biotic factors as bottlenecks controlling vital rates and transitions from seeds to adult trees. The role played by domestic grazing on woody encroachment is yet controversial. Here, using a multistage tree life approach, we combine both models and evaluate the role of grazing and herbaceous vegetation on woody recruitment in a Neotropical savanna dominated by Vachellia caven, a successful and widely spread encroacher tree species. We performed three experiments to evaluate seed predation, seedling emergence and survival of V. caven by manipulating cattle grazing (grazed and ungrazed areas) and herbaceous vegetation presence (vegetated and unvegetated). Finally, we combined the results of the three experiments to estimate the probability of plant recruitment across these experimental factors. Grazing decreased seed predation by half, did not modify seedling emergence and decreased seedling survival. Herbaceous vegetation did not affect seed predation nor seedling emergence rate, but increased seedling survival. Overall, the net effect of grazing on V. caven recruitment was neutral since the increase in seed availability due to the reduction in seed predation rate was compensated by the negative effect of grazing on seedling survival. Our analysis revealed that cattle grazing and herbaceous vegetation had contrasting effects on the seed and seedling life stages. We propose that in order to restrain the early stages of encroachment, cattle grazing pressure could be managed following the seasonality of demographic tree transitions. Through rotational grazing amongst paddocks, stocking rates could be relaxed during the primary dispersal stage to maximize granivory, and then increased to enhance the chance of seedling consumption and trampling.

Understanding herbivore-plant-soil feedbacks to improve grazing management on Mediterranean mountain grasslands

The surface of many European mountain grasslands is decreasing due to global change and extensive grazing stands out as a key tool for their conservation. Sound knowledge of grassland ecosystem functioning and its feedback processes is required to implement sustainable grazing management. This study aimed to understand the effect of different grazing intensities on herbivore-plant-soil feedbacks in Mediterranean mountain grasslands. We estimated spatial distribution of sheep grazing intensity using GPS technology in order to assess the effect of grazing pressure on vegetation and soil properties measured throughout the study area. Our results showed that grazing intensity ranged from 0.06 to 2.85 livestock units / ha, corresponding to a gradient of pasture utilisation rates varying from 2.38% to 45.60% of annual productivity from pasture. Increasing grazing pressure was associated with smaller relative cover and species richness of non-leguminous forbs, while the opposite trends were observed for graminoids. Forage had a greater concentration of N and smaller C:N ratio in more heavily grazed areas. Increasing grazing intensity was also associated with higher values of total soil N, NO3-, NH4+, soil organic carbon, microbial biomass C and activity of β-glucosidase. Higher litter quality was the main factor explaining greater content of soil organic matter, which favoured both soil microbes and plant productivity. Grazing induced changes in the plant community triggered positive hervibore-plant-soil feedbacks, as they ultimately improved forage quality and productivity, which significantly influenced the pasture preference of free-ranging domestic grazers. Our work showed that grazing management aiming pasture utilisation rates of around 45% is critical in sustaining positive herbivore-plant-soil feedbacks and preserving or enhancing the whole ecosystem functioning in the Mediterranean mountain grasslands studied.

Holocene lake phosphorus species and primary producers reflect catchment processes in a small, temperate lake

AbstractThis paleolimnological study aims to investigate how natural processes and anthropogenic land‐use changes have affected sedimentary phosphorus (P) forms and primary producers in a small, temperate lake (Lake Fuglsø, Denmark) throughout the Holocene. Our multi‐proxy approach uses pollen, X‐ray fluorescence scanning, carbon (C) and nitrogen contents and stable isotopes, sequential P extraction, 31P nuclear magnetic resonance spectroscopy, pigments, diatoms, and plant macrofossils from a 14C‐dated sediment record. We found three periods of human impact: (1) low disturbance from domestic grazing during the early/mid Neolithic (~3600 to ~2600 BC), (2) higher disturbance because of animal husbandry and some grain cultivation during the Late Bronze and Pre‐Roman Iron Age (~800 BC to AD ~100), and (3) strong disturbance caused by domestic grazing, intensified crop cultivation and, in particular, by retting of fiber plants during the Middle Ages and Renaissance (AD ~1000 to ~1700). Cultural eutrophication during the latter phase caused unprecedented changes in the lake, including altered species composition, high production, and strongly accelerated sediment accumulation rates. Generally, catchment deforestation was related to elevated proportions of metal (iron, aluminum, calcium)‐bound P forms in the sediment, while high tree cover correlated with elevated proportions of P forms associated with organic material (“organic” P, humic‐bound P, refractory organic P) and loosely bound P. During phases with forest in the catchment, silicon (Si) inputs to the lake were insufficient and diatom frustules were mostly absent in the sediments. In contrast, diatoms thrived in the lake when the landscape was open and erosional Si influx was high. This study is the first to show long‐term (~eight millennia) and recurring Si limitation of diatoms, a finding that may explain the absence of diatoms in sediment records of other sites too. In summary, human land‐use with preceding deforestation accelerated the transport of nutrients and elements from the terrestrial to the aquatic environment, leading to substantial and irreversible changes in Lake Fuglsø. Our study is a good example of the tight links between catchment processes and lake status, indicating that catchment dynamics should be considered in lake restoration projects, particularly for lowland lakes with high catchment : lake area ratios.

Plant quality and primary productivity modulate plant biomass responses to the joint effects of grazing and fertilization in a mesic grassland

AbstractQuestions: Human activities are increasing the density of domestic grazers and global nutrient loads, modifying the main determinants of vegetation community dynamics. Grazing (top‐down control) and nutrient availability (bottom‐up control) may interactively modify plant biomass, which is particularly important in grasslands devoted to livestock production. Here, we aim to understand the interactive effects of grazing and fertilization on grassland plant biomass. We hypothesized that the joint effects of nutrient addition and domestic grazing on above‐ground plant biomass are not additive, but they modify each other through changes in ground‐level light, leaf nutritional quality, above‐ground net primary productivity (ANPP), and below‐ground plant allocation.Location: Flooding Pampa (Buenos Aires, Argentina).Methods: We carried out a factorial experiment of grazing exclusion and fertilization with nitrogen, phosphorus, and potassium + micronutrients during ​several years in a mesic grassland devoted to livestock production.Results: After four years, grazing reduced live above‐ground plant biomass by 52%, and when combined with fertilization this reduction was 70%. Nutrient addition in the grazed grassland increased ANPP and leaf nutrient concentration. These changes in turn intensified grazing pressure and cattle’s plant consumption. By contrast, fertilization did not produce any significant effect on plant biomass or ANPP inside the exclosures, where ground‐level light was low. A structural equation model revealed that the increase in ANPP fostered above‐ground and reduced below‐ground plant biomass.Conclusions: This is the first study conducted in the Pampas grasslands that evaluated the effect of cattle grazing and fertilization on plant communities under field conditions over several years. Grazing and nutrient addition synergistically controlled grassland plant biomass, as the reduction in above‐ground biomass by cattle consumption was greater in fertilized plots. Our results provided empirical evidence that leaf nitrogen and ANPP modulated plant biomass dynamics in grasslands devoted to livestock production in the context of increased nutrient loads in terrestrial ecosystems.

Sheep grazing differentially affects the canopy attributes and functional diversity of shrubs and perennial grasses in arid rangelands

We analysed how changes in community attributes promoted by domestic grazing are reflected on functional traits in canopies of shrubs and perennial grasses in rangelands of the Patagonian Monte. We selected four sites across a gradient of grazing pressure and assessed (i) changes in plant cover, and species richness and diversity and (ii) changes in functional traits (community weighted mean: CWM, functional diversity and redundancy) related to plant growth (leaf N concentration, height of the plant, and specific leaf area-SLA) in shrub and perennial grass canopies. Shrub cover decreased and species and functional diversity increased with increasing grazing pressure. Nonsignificant changes were found in shrub species richness and functional redundancy across the grazing gradient. Positive relationships were found between shrub species diversity and CWM of SLA, and leaf N, while CWM-height was not related to grazing pressure. Perennial grass cover decreased steadily with grazing pressure, while species richness decreased significantly at high grazing pressure. Perennial grass diversity, functional diversity and redundancy of functional plant traits, and CWM-height increased at intermediate grazing pressure, while the inverse pattern was observed for CWM of SLA and leaf N. These results highlighted that species diversity was the community attribute that best reflected functional changes induced by grazing pressure in shrub and perennial grass canopies in these rangelands. We concluded that shrubs persist under high grazing pressure increasing species and functional diversity of relevant plant traits, while perennial grass canopies were only able to persist under intermediate grazing pressure.

Wild guanacos as scapegoat for continued overgrazing by livestock across southern Patagonia

Abstract In a recently published paper, Oliva et al. concluded that domestic grazing pressure across Patagonian rangelands approached carrying capacity due to decades of stock adjustment, but that guanaco overpopulation may have altered that balance. The authors argued that unless guanaco numbers are controlled, they will reduce forage available for domestic stock and will negatively affect rangelands. We consider that the herbivore‐stock analysis presented is inaccurate and deserves revision, and that the stated conclusions lack empirical support. When the spatial distribution of herbivores is accounted for in the Oliva et al. analysis, domestic stock is far above carrying capacity, indicating that domestic overgrazing continues. Theoretical and empirical evidence on bottom‐up regulation and competitive exclusion challenges the supposed guanaco overpopulation and the hypothetical reduction of forage available for livestock. Even if guanaco numbers are reduced, grassland degradation and production losses will continue because their main drivers, domestic overstock and heterogeneous grazing, are still operating. Synthesis and applications. Oversimplified models with poor ecological insight can lead to erroneous conclusions and misguide management decisions. The incorrect inference that Patagonian domestic stock is adjusted to carrying capacity could help to consolidate current domestic overgrazing by reducing incentives to improve livestock management practices. Regarding guanacos, a controversial species in an unfavourable context, control‐oriented harvest without a clear justification threatens populations’ viability and genuine attempts of productive diversification. Addressing relevant ecological processes, such as niche partitioning, competitive exclusion and population regulation, is essential to correctly assess joint carrying capacity in multi‐herbivore systems, as well as to identify the true factors driving degradation processes and to optimize rangeland use on a sustainable basis.

Survey of rumen microbiota of domestic grazing yak during different growth stages revealed novel maturation patterns of four key microbial groups and their dynamic interactions

BackgroundThe development and maturation of rumen microbiota across the lifetime of grazing yaks remain unexplored due to the varied lifestyles and feed types of yaks as well as the challenges of obtaining samples. In addition, the interactions among four different rumen microbial groups (bacteria, archaea, fungi and protozoa) in the rumen of yak are not well defined. In this study, the rumen microbiota of full-grazing yaks aged 7 days to 12 years old was assessed to determine the maturation patterns of these four microbial groups and the dynamic interactions among them during different growth stages.ResultsThe rumen microbial groups (bacteria, archaea, protozoa and fungi) varied through the growth of yaks from neonatal (7 days) to adult (12 years), and the bacterial and archaeal groups were more sensitive to changes in growth stages compared to the two eukaryotic microbial groups. The age-discriminatory taxa within each microbial group were identified with the random forest model. Among them, Olsenella (bacteria), Group 10 sp., belonging to the family Methanomassiliicoccaceae (archaea), Orpinomyces (fungi), and Dasytricha (protozoa) contributed the most to discriminating the age of the rumen microbiota. Moreover, we found that the rumen archaea reached full maturation at 5 approximately years of age, and the other microbial groups matured between 5 and 8 years of age. The intra-interactions patterns and keystone species within each microbial group were identified by network analysis, and the inter-interactions among the four microbial groups changed with growth stage. Regarding the inter-interactions among the four microbial groups, taxa from bacteria and protozoa, including Christensenellaceae R-7 group, Prevotella 1, Trichostomatia, Ruminococcaceae UCG-014 and Lachnospiraceae, were the keystone species in the network based on betweenness centrality scores.ConclusionsThis study depicted a comprehensive view of rumen microbiota changes in different growth stages of grazing yaks. The results revealed the unique microbiota maturation trajectory and the intra- and inter-interactions among bacteria, archaea, fungi and protozoa in the rumen of grazing yaks across the lifetime of yaks. The information obtained in this study is vital for the future development of strategies to manipulate rumen microbiota in grazing yaks for better growth and performance in the harsh Qinghai-Tibetan Plateau ecosystem.

Aridity exacerbates grazing‐induced rangeland degradation: A population approach for dominant grasses

Abstract The current human‐induced intensification of grazing pressure and the aridity increase as a result of climate change are unprecedented and have been identified as the main drivers that cause desertification in rangelands world‐wide. In these ecosystems, human well‐being mostly depends on plant species that provide forage for domestic herbivores. However, scarce evidence exists about the interaction between regional aridity level and human‐induced disturbances as determinants of forage plant populations' structure and dynamics. We studied the effects of domestic grazing intensification on the population structure of dominant native grasses, in three rangeland sites located across a regional aridity gradient: a semi‐desert (high‐aridity site), a shrub–grass steppe (intermediate‐aridity site) and a grass steppe (low‐aridity site). We also studied the effect of 2‐year grazing exclusion on the growth of defoliated plants of a key native forage grass species common to the three sites. Grazing decreased total grass density and increased the frequency of small plants in all sites, particularly for forage species. However, the size of the grazing intensification effect was the greatest in the high‐aridity site, where intensive grazing produced a ten‐fold reduction of grass density. Moreover, defoliated plants recovery (growth) was lower as aridity increased. Synthesis and applications. Our study provides evidence of a negative synergistic effect of grazing pressure and aridity that may lead to the collapse of grass populations. Long‐term grazing intensification degrades the population structure of grasses, particularly in high‐aridity sites, where the forage provision is substantially reduced. These results refute the hypothesis that plant traits of dominant species adapted to high aridity allow them to resist herbivory. Besides, high aridity delays plant recovery after defoliation (low resilience). The management of both grazing pressure and the length of grazing rest according to ecological‐site aridity are key aspects for maintaining the forage provision of rangelands. Monitoring plant populations' structure through time and space strengthens inferences about responses of forage species to ongoing changes in disturbance and stress regimes. This knowledge is complementary to regional and world‐wide monitoring endeavours based on land cover, and it contributes to the robust design of sustainable management of global rangelands.

Ecology eclipses phylogeny as a major driver of nematode parasite community structure in a graminivorous primate.

Understanding the relative strength of ecology and phylogeny in shaping parasite communities can inform parasite control and wildlife conservation initiatives while contributing to the study of host species evolution.We tested the relative strengths of phylogeny and ecology in driving parasite community structure in a host whose ecology diverges significantly from that of its closest phylogenetic relatives.We characterized the gastrointestinal (GI) parasite community of wild geladas (Theropithecus gelada), primates that are closely related to baboons but specialized to graminovory in the Ethiopian Highlands.Geladas exhibited very constrained GI parasite communities: only two genera (Oesophagostomum and Trichostrongylus) were identified across 303 samples. This is far below the diversity reported for baboons (Papio spp.) and at the low end of the range of domestic grazers (e.g., Bos taurus, Ovis aries) inhabiting the same region and ecological niche.Using deep amplicon sequencing, we identified 15 amplicon sequence variants (ASVs) within the two genera, seven of which matched to Oesophagostomum sp., seven to Trichostrongylus sp., and one to T. vitrinus.Population was an important predictor of ASV richness. Geladas in the most ecologically disturbed area of the national park exhibited ~4x higher ASV richness than geladas at a less disturbed location within the park.In this system, ecology was a stronger predictor of parasite community structure than phylogeny, with geladas sharing more elements of their parasite communities with other grazers in the same area than with closely related sister taxa.

Grazing impact on structure and dynamics of bare soil areas in a Patagonian grass-shrub steppe

Bare soil is an idiosyncratic and important feature of arid ecosystems that can be affected by human land use such as domestic grazing intensification. Here we focused on the study of individual bare soil areas (BSA) and their long-term dynamics using DINVEG (spatially-explicit simulation model). In Patagonian rangelands we photographed BSA in grazed and ungrazed stands (n = 50). Compared with exclosure, grazing increased the size of the BSAs (17%, p < 0.05) and produced less irregular forms (13%, p < 0.05). The number of plants that delimit BSAs were not different (~9), but under grazing the sum of spaces among plants (BSA opening) was 15% higher than in exclosure (p < 0.05). The difference in wind speed (center-edge of the BSA) increased 70% under grazing. Wind difference was poorly correlated with the BSAs structure variables. Simulations (200 years) with DINVEG indicated that grazing decreased the likelihood of BSAs being colonized by grasses and increased the proportion of bare soil cells. Our study suggests that in these Patagonian steppes domestic grazing promotes structural changes in individual BSA and in the transition to grass covered patches. Changes in wind speed may result from grazing effect at the whole vegetation mosaic since BSA features are not enough to explain differences.

GIS-Based Gully Erosion Susceptibility Mapping: A Comparison of Computational Ensemble Data Mining Models

Gully erosion destroys agricultural and domestic grazing land in many countries, especially those with arid and semi-arid climates and easily eroded rocks and soils. It also generates large amounts of sediment that can adversely impact downstream river channels. The main objective of this research is to accurately detect and predict areas prone to gully erosion. In this paper, we couple hybrid models of a commonly used base classifier (reduced pruning error tree, REPTree) with AdaBoost (AB), bagging (Bag), and random subspace (RS) algorithms to create gully erosion susceptibility maps for a sub-basin of the Shoor River watershed in northwestern Iran. We compare the performance of these models in terms of their ability to predict gully erosion and discuss their potential use in other arid and semi-arid areas. Our database comprises 242 gully erosion locations, which we randomly divided into training and testing sets with a ratio of 70/30. Based on expert knowledge and analysis of aerial photographs and satellite images, we selected 12 conditioning factors for gully erosion. We used multi-collinearity statistical techniques in the modeling process, and checked model performance using statistical indexes including precision, recall, F-measure, Matthew correlation coefficient (MCC), receiver operatic characteristic curve (ROC), precision–recall graph (PRC), Kappa, root mean square error (RMSE), relative absolute error (PRSE), mean absolute error (MAE), and relative absolute error (RAE). Results show that rainfall, elevation, and river density are the most important factors for gully erosion susceptibility mapping in the study area. All three hybrid models that we tested significantly enhanced and improved the predictive power of REPTree (AUC=0.800), but the RS-REPTree (AUC= 0.860) ensemble model outperformed the Bag-REPTree (AUC= 0.841) and the AB-REPTree (AUC= 0.805) models. We suggest that decision makers, planners, and environmental engineers employ the RS-REPTree hybrid model to better manage gully erosion-prone areas in Iran.

Fine‐scale variables associated with the presence of native forbs in natural temperate grassland

AbstractBroad‐scale threats to floristic diversity in native temperate grasslands are well‐documented and include elevated soil nutrients, changes in disturbance regimes and exotic species. However, fine‐scale variables associated with the presence of native forbs, such as gap size and biomass cover, have received relatively little attention. We conducted a case–control study to determine the relative influence of physical structural dimensions and other fine‐scale variables associated with the presence of native forbs in a modified temperate grassland previously used for domestic grazing. We matched 145 case plots centred on 27 different species of native forbs with 290 control plots not centred on a native forb. For each percentage increase in ground litter cover, dead biomass cover, grass cover or exotic forb cover, or the area of bare ground within 30 cm, the relative odds that a native forb was present vs absent declined by a mean of 10–13%. Living and dead biomass reduces light availability, and the former can also reduce nutrient and water availability. Declines in the presence of native forbs associated with increasing total bare ground may suggest that gap sizes were too small or the soil surface condition too degraded. Our results add to a body of evidence suggesting that native forbs in temperate native grassland are likely to benefit from periodic removal of living and dead grass biomass and a reduction in the cover of exotic forbs.