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729 results for “Grazing”
Grazing and microhabitat interact to affect plant-plant interactions in subtropical seasonal wetlands, 2007-2008
The stress gradient hypothesis predicts that competition will be important in productive environments while facilitation will be common in environments with high stress or consumer pressure. However, abiotic stress and grazing may vary independently and even occur simultaneously. Here we examine the outcome of plant interactions in grazed wetlands where consumer pressure and abiotic stress occur concurrently. We hypothesized that cattle grazing and microhabitat would alter the outcome of plant interactions. Given that wetland edges are drier and less productive than wetland centers we expected that facilitation would be greatest in drier wetland edges due to greater abiotic stress regardless of cattle presence. We conducted an experiment for two growing seasons in ten wetlands, five exposed to cattle grazing and five fenced. Two wetland obligate plants were included (Panicum hemitomon and Alternanthera philoxeroides), and plots were assigned to three treatments 1) all neighbors removed, 2) all neighbors removed except Juncus effusus, a dominant, unpalatable plant, 3) all neighbors intact (control), in both wetland centers and edges. Differences in survival, change in height and number of leaves were assessed. In ungrazed wetlands, plant survival was higher in wetland edges vs. centers, while it did not differ in grazed wetlands. Survival in wetland edges was further increased by the presence of J. effusus. Positive interactions under grazed conditions were clear when plant height was assessed, but negative interactions affected leaf production in both ungrazed and grazed wetlands. Grazing interacts with wetland microhabitat to alter plant survival. Facilitative interactions on plant height were apparent in grazed wetlands. Understanding how plant interactions change under different biotic and abiotic contexts is important for informing ecosystem restoration and management.
McMurdo Dry Valleys Microzooplankton : Flagellate Grazing in Lakes Hoare and Fryxell
In conjunction with the Long Term Ecological Research (LTER) project in the McMurdo Dry Valleys of Antarctica, lakes were monitored for microzooplankton by a team based out of the University of Nottingham (led by Johanna Laybourn-Parry). This dataset shows grazing rates of heterotrophic and mixotrophic flagellates found in Lakes Hoare and Fryxell at various depths and dates.
McMurdo Dry Valleys Microzooplankton : Ciliate Grazing Rates
In conjunction with the Long Term Ecological Research (LTER) project in the McMurdo Dry Valleys of Antarctica, lakes were monitored for microzooplankton by a team based out of the University of Nottingham (led by Johanna Laybourn-Parry). This dataset shows grazing rates of ciliates feeding on cryptophytes between November 1997 and January 1998. The sample for this micro dataset was gathered at the Lake Fryxell.
SBC LTER: REEF: Data to support "Niche Complementarity and Resistance to Grazing Promote the Invasion Success of Sargassum horneri in North America"
These data describe the results of surveys and manipulative experiments performed to investigate how niche complementarity, competition, and herbivory influence the success of the invasive seaweed Sargassum horneri. This data package includes five data tables and they are used to support the manuscript: Marks LM, Reed DC, Holbrook SJ (2020) Niche Complementarity and Resistance to Grazing Promote the Invasion Success of Sargassum horneri in North America. Diversity, 12(2)
Dataset accompanying Riesch et al. 2020. Grazing by wild red deer maintains characteristic vegetation of semi-natural open habitats: Evidence from a 3-year exclusion experiment. Applied Vegetation Science
<p>This repository contains vegetation community data used by Riesch et al. 2020 in an article accepted in Applied Vegetation Science.</p> <p>Metadata are provided in the first excel worksheet. For further details please see the original article.</p>
Data from: Aridity exacerbates grazing-induced rangeland degradation: a population approach for dominant grasses
<p>1. The current human-induced intensification of grazing pressure and the increase of aridity as a result of climate alterations are unprecedented and have been identified as the main drivers that cause desertification in rangelands worldwide. 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.</p> <p>2. 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 two-year grazing exclusion on plant growth of a key native forage grass species common to the three sites.</p> <p>3. 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, plant recovery (growth) after grazing exclusion was lower as aridity increased.</p> <p>4. 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 the grazing pressure and the length of grazing-rest according to the 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 worldwide monitoring endeavors based on land cover, and it contributes to the robust design of sustainable management of global rangelands.</p>
Livestock and kangaroo grazing have little effect on biomass and fuel hazard in semi-arid woodlands
<ol> <li>Using livestock grazing as a tool to manage biomass and reduce fuel hazard has gained widespread popularity, but examples from across the globe demonstrate that it often yields mixed, context-dependent results. Grazing has potential to deliver practical solutions in systems where grazing reduces not only biomass but also reduces fuel hazard by altering vegetation connectivity or composition.</li> <li>We assessed the extent to which recent rainfall, rabbit and kangaroo grazing and recent and historic livestock grazing alters and accounts for variation in above-ground biomass, biomass composition and fuel hazard ratings across three broad communities in eastern Australia. We used nested linear models to assess biomass in three vertical vegetation strata, that matched the strata assessed in the Overall Fuel Hazard Assessment guide (i.e. litter/surface fuel; groundstorey vegetation/near surface fuel; and midstorey vegetation/elevated fuel) and Ordinal Logistic Regression to assess categorical fuel hazard ratings.</li> <li>Only recent kangaroo grazing reduced groundstorey biomass across all communities. Kangaroo grazing altered litter mass and significantly reduced surface fuel hazard in one community. Recent livestock grazing did not reduce fuel hazard, and despite significantly reducing half of our measures of biomass, these were not practical reductions. For instance, livestock grazing significantly reduced litter mass, however our model predicts that doubling our assessment of livestock grazing intensity only reduces total litter mass by 0.8 %, or 8 kg per hectare in landscapes where average litter loads ranged from 3,600 to 12,600 kg per hectare. Furthermore, long-term livestock grazing increased shrub biomass and in one community this increased elevated fuel hazard. There were few effects of rabbits. The effects of rainfall on biomass were up to an order of magnitude greater than any effects due to grazing.</li> <li> <i>Synthesis and applications:</i> Our data suggest that management practices that seek to use livestock grazing to reduce biomass in these systems will not achieve practical reductions in biomass and or fuel hazard.</li> </ol>
Grazing and climate change have site-dependent interactive effects on vegetation in Asian montane rangelands
<p>1. Climate over Asian montane rangelands is changing faster than the global average, posing serious threats to the future of the region's livestock-based economies and cultures. Effects of climate change on rangeland vegetation likely depend on grazing by herbivores but the potential responses of vegetation to such changes in climate and grazing regimes remains unclear.</p> <p>2. We examined vegetation responses to experimentally simulated climate change (warming, drought and increased rainfall) and grazing (clipping vegetation) between 2015-2018 at two mountain rangeland sites: Spiti valley, in the Indian Trans-Himalaya and Tost, in the Gobi-Altai Mountains in Mongolia.</p> <p>3. Clipping and climate change manipulations interactively reduced vegetation cover and biomass but did not affect species richness. Treatment effects and their interactions varied between sites. In ungrazed plots, vegetation cover and biomass declined sharply in response to warming (18-35%) and drought (20-50%) at the two sites, and, surprisingly also declined slightly in response to increased rainfall (20%) at Tost. While the effects of climate treatments were largely similar in the grazed and ungrazed plots in Tost, they were larger in the ungrazed plots in Spiti. The decline in vegetation cover was driven by a decline in the cover of both forbs and grasses.</p> <p>4. In combination, grazing and warming (Tost) or drought (Spiti) had sub-additive effects, i.e., the decrease in vegetation cover in response to grazing and warming/drought was less than the sum of their independent effects but greater than the effect of either manipulation alone. Of the two, warming had a greater effect than drought at the more arid site (Tost), while drought had a larger effect at the more mesic site (Spiti). <i>Synthesis and applications. </i>Our findings show that<i> </i>future changes in climate, including just over 1<sup>o</sup>C of warming, could undermine the sustainability of pastoral economies and the persistence of wildlife across Asian montane rangelands. Further, grazing by herbivores will play an important role in mediating rangeland responses to climate change; thus, pasture management in concert with local pastoralists will be crucial in mitigating the adverse effects of climate change on rangelands, pastoral livelihoods and wildlife populations.</p>
Grazing intensity significantly changes the C:N:P stoichiometry in grassland ecosystems
<p> </p> <p>Aim: Livestock grazing can alter carbon (C), nitrogen (N) and phosphorus (P) cycles, thereby affecting the C:N:P stoichiometry in grasslands. In this study, we aimed to examine the underlying mechanisms for the impacts of grazing intensity on grassland C:N:P stoichiometry, especially for the belowground processes and their linkages with aboveground vegetation properties.<br> Location: Global.<br> Time period: 1900-2018.<br> Major taxa studied: Grassland ecosystems.<br> Methods: Here, we conducted a meta-analysis based on 129 published studies to synthesize the effects of grazing on the C:N:P stoichiometry of leaves, stems, litter, roots, microbial biomass, and soil in grassland ecosystems.<br> Results: Grazing significantly affected the C, N and P pools, and then the C:N:P stoichiometry in grassland ecosystems. Grazing effects on C:N:P stoichiometry varied strongly with grazing intensity. Specifically, heavy grazing decreased all C:N:P stoichiometry except litter N:P and root C:N ratios, while light and moderate grazing exhibited the less negative or positive effects. Grazing effects on litter C:N ratio were negatively correlated with grazing effects on soil C:N ratios under light and moderate grazing, but this relationship was positive under heavy grazing. In contrast, the correlation between grazing effect on root C:P and soil C:P was positive under light and moderate grazing but negative under heavy grazing. Importantly, grazing significantly decreased soil N pool by 10.0% but increased P pools by 3.6%, indicating differential mechanisms for grazing impact on N and P cycles in grasslands.<br> Main conclusions: The divergent effects of light, moderate, and heavy grazing on the C:N:P stoichiometry highlight the importance of grazing intensity in regulating the biogeochemical cycles of C, N, and P by accelerating plant nutrient use efficiency and inducing changes in soil physicochemical processes in grassland ecosystems. Therefore, incorporating grazing intensity into Earth system models may improve predictions of climate-grassland feedbacks in the Anthropocene.</p>
Shifts in plant composition mediate grazing effects on carbon cycling in grasslands
<p> </p> <p>Carbon cycling in grasslands can be impacted by livestock grazing, partially as an indirect result of herbivory-induced compositional shifts in the plant community. However, the underlying mechanisms of how these shifts impact carbon cycling are not well documented.</p> <p>We conducted a long-term grazing experiment with four sheep stocking rates in the semi-arid grasslands of Inner Mongolia, China, to examine grazing effects on the ratio of C<sub>3</sub> to C<sub>4</sub> species (C<sub>3</sub>:C<sub>4</sub>), shoot biomass, root biomass, root:shoot, soil respiration, soil C, soil N, and soil C:N between 2014 and 2018. We explored the responses of these carbon metrics to C<sub>3</sub>:C<sub>4</sub> under different grazing treatments and the mechanisms driving grazing-induced carbon loss using structural equation models.</p> <p>Livestock grazing directly shifted plant community composition (i.e., increasing C<sub>3</sub>:C<sub>4</sub>) and reduced vegetation carbon (i.e., shoot biomass), whereas grazing effects on belowground carbon were mediated by the interactions of the soil profile (i.e., depth-dependence) and year-to-year variation (e.g., rainfall regulation). Grazing-induced increases in C<sub>3</sub>:C<sub>4 </sub>suppressed soil carbon loss by inhibiting the rate of soil respiration. Furthermore, grazing intensity indirectly altered these relationships. Specifically, C<sub>3</sub>:C<sub>4 </sub>was<sub> </sub>positively related to shoot biomass and negatively associated with root:shoot, soil C, and soil N, whereas these relationships were only significant in no-grazed plots. Meanwhile, soil respiration was negatively associated with C<sub>3</sub>:C<sub>4</sub>, soil C, soil N, and soil C:N, but a positive relationship with shoot biomass; these relationships were significant only in grazed-plots.</p> <p><a> <i>Synthesis and applications.</i></a> Our findings emphasize the functional linkages between community characteristics and ecosystem processes, i.e. shifts in plant community composition play a key role in regulating grassland carbon cycling. These results provide a useful field-observed resource for model development and could improve the guidelines for livestock management and policies regarding climate <a>mitigation.</a></p> <p> </p>
Legacy effect of grazing intensity mediates the bottom-up controls of resource addition on soil food webs
<p>1. Large-scale studies have demonstrated that nitrogen (N) and water (W) availability greatly affect terrestrial ecosystems worldwide, and this is especially true for the resource-poor semi-arid grasslands. Yet, experimental evidence is lacking for how N and W availability affect soil food webs across historical grazing intensity-altered environments at a local scale.</p> <p>2. Here, we included N- and W-addition treatments in an 8-year grazing experiment (with four grazing intensities) to determine how the legacy effects of grazing intensity mediate the responses of key components of soil food webs (plants, microorganisms, and nematodes) to resource addition in a semi-arid grassland.</p> <p>3. After 4 years of N- and W-addition treatments (with no grazing during that 4-year period), we found that a legacy of grazing, even light grazing, had significant negative effects on the components of plant community and soil food webs. Both N and W addition increased above- and below-ground plant biomass, especially under moderate and heavy grazing. N addition had negative effects on the biomass of bacteria under no grazing, while W addition increased the biomass of actinomycetes under light grazing. N addition decreased the abundance of omnivorous + carnivorous nematodes under light and heavy grazing, while W addition increased their abundance under heavy grazing. Overall, the effects of resource addition on soil food webs progressively decreased from the lowest trophic level (primary producers, i.e., plants), to intermediate tropic levels (microorganisms and root-feeding nematodes), to higher trophic levels (microbial-feeding nematodes and omnivorous + carnivorous nematodes).</p> <p>4. Synthesis and applications. Our results, which are the first data concerning the effects of resource addition on key components of soil food webs across a historical grazing-induced environmental gradient, show that the strong bottom-up controls of resource addition on soil food webs are mediated by the legacy of grazing intensity. These finding should be useful for predicting the responses of grassland ecosystems to future climate change and suggest that the recovery of degraded grasslands will require more than restoration measure of resource inputs alone.</p>
Data from: Influences of patch-burn grazing on headwater prairie streams and subsequent recovery
<p>1. Patch-burn grazing (PBG) can promote terrestrial heterogeneity and biodiversity, but can temporarily increase stream nutrients, ecosystem metabolism, and alter macroinvertebrate assemblages. The impacts of grazing on stream channel morphology and post-PBG recovery patterns are unclear. 2. We assessed the influence of grazing in PBG managed grassland streams in Missouri, USA, and subsequent recovery when grazing ceased for two years. We hypothesized that grazing would degrade water quality, stream biotic integrity, and channel morphology, but that riparian fencing would mitigate these effects. We predicted that biological and chemical variables in unfenced streams would return to pre-PBG levels within two years after grazing ceased, but channel morphology would not. 3. Six small headwater streams (two in ungrazed control watersheds, two in PBG watersheds with 10 m fenced riparian zones, and two in unfenced PBG) were sampled over seven years; 2 years before PBG, 3 years during PBG, and 2 years post-PBG. We sampled macroinvertebrates and water chemistry monthly when water was present and surveyed channel morphology at least once each study period. 4. During grazing, unfenced watersheds showed the greatest changes in channel width, depth, and area. During the post-PBG period, one of the two unfenced watersheds showed partial recovery of channel morphology. Although grazing increased concentrations of nutrients and chlorophyll a, concentrations returned to pre-PBG conditions after grazing ended, indicating recovery. Very fine organic sediments increased in the unfenced watersheds compared to the control during grazing but recovered afterwards. Contributions of Chironomidae to total invertebrate abundance increased in the unfenced watersheds during grazing, and then decreased during the post-PBG period. 5. Riparian fencing mostly mitigated effects of grazing on the streams. Unfenced streams were resilient to effects of grazing in a PBG managed grassland, with most metrics recovering within two years after grazing ceased, except for channel morphology. 6. Synthesis and applications: Grazing in a PBG managed grassland coupled with riparian fencing could be an effective conservation tool in prairies, with relatively modest influences on stream water quality and biotic integrity. Persistent changes in stream geomorphology and effects of longer periods of grazing deserve further research.</p>
Data from: Knowledge co-production with traditional herders on cattle grazing behaviour for better management of species-rich grasslands
The research gap between rangeland/livestock science and conservation biology/vegetation ecology has led to a lack of evidence needed for grazing-related conservation management. Connecting scientific understanding with traditional ecological knowledge of local livestock keepers could help bridge this research and knowledge gap. 1. We studied the grazing behaviour (plant selection and avoidance) of beef cattle (ca. 33 000 bites) on species-rich lowland pastures in Central Europe and traditional herding practices. We also did >450 outdoor interviews with traditional herders about livestock behaviour, herders' decisions to modify grazing behaviour, and effects of modified grazing on pasture vegetation. 2. We found that cattle grazing on species-rich pastures displayed at least 10 different behavioural elements as they encountered 117 forage species from highly desired to rejected. The small discrimination error suggests that cattle recognize all listed plants 'by species'. 3. We also found that herders had broad knowledge of grazing desire and they consciously aimed to modify desire by slowing, stopping or redirecting the herd. Modifications were aimed at increasing grazing intensity in less desired patches and decreasing grazing selectivity in heterogenous swards. 4. Synthesis and applications: These traditional herd management practices have significant conservation benefits, such as avoiding under- and overgrazing, and targeted removal of pasture weeds, litter and enchroaching bushes, tall competitive plants and invasive species. We argue that knowledge co-production with traditional herders who belong to another knowledge system could help connect isolated scientific disciplines especially if ecologists and rangeland scientists work closely with traditional herders, co-designing research projects and working together in data collection, analysis and interpretation. Stronger links between these disciplines could help develop evidence-based, specific conservation management practices while herders could contribute with their practical experiences and with real world testing of new management techniques.04-May-2020
Data from: Cascading effects of earthworm invasion in tundra increase graminoid density and rodent grazing intensities
<p>Earthworms are being introduced to numerous ecosystems through human activities. Some non-native earthworm species have the potential to 'geoengineer' soils and increase plant nitrogen (N) uptake, but if the increased plant N concentrations can cause increased rodent grazing is not well known. In this study, we present findings from a common garden experiment with two tundra communities, meadow (forb dominated) and heath (shrub dominated), half of them subjected to four years of earthworm presence (<em>Lumbricus</em> spp. and <em>Aporrectodea</em> spp.). Within four summers, our earthworm treatment changed plant community composition by increasing graminoid density by on average 94 % in the heath vegetation and by 49 % in the meadow. Rodent winter grazing were more intense on plants growing in soils with earthworms, an effect that coincided with higher nitrogen concentrations in plants indicating a higher palatability. Moreover, although the earthworms decreased soil moisture, our proxy for plant community photosynthesis (greenness) was not negatively affected. We conclude that earthworm-induced changes in plant composition and trophic interactions may radically alter the functioning of tundra ecosystems.</p>
Fertilization can accelerate the pace of soil microbial community response to rest-grazing duration in the Three-river Source Region of China
<div> <div> <p><strong><span>Objectives</span></strong> </p> <p><span>Overgrazing leads to grassland degradation and productivity decline. Rest-grazing during the regreen-up period can quickly restore grassland and fertilization is a common restoration measure. Meanwhile, soil microorganisms are more sensitive indicators. Therefore, the experiment of rest-grazing time and fertilization was carried out to explore the response of soil microorganisms to rest-grazing time and fertilization measures. </span></p> <p><span><strong>Methods</strong> </span></p> <p><span>A field control experiment with rest-grazing time and fertilization as factors was conducted from the time when grass returned to green till the livestock moved to the summer pasture in Dawu Town of Maqin County.</span> <span>The primary treatment we established was the five</span> <span>rest-grazing times, including rest-grazing times of 20 days, 30 days, 40 days, 50 days, and traditional grazing was used as a check group. At the same time, the secondary treatment was nitrogen addition of 300 kg·hm<sup>-2</sup> in each primary treatment. </span></p> <p><span><strong>Results</strong> </span></p> <p><span>The results showed that: the total phospholipid fatty acid (total PLFA), actinomyces (Act) and arbuscular </span><span>mycorrhizal fungi (AMF) showed an ever-increasing biomass with the increase of rest-grazing time and the highest was at 50 days of rest-grazing, and they were all significantly higher than CK. In addition, soil microbial biomass carbon-nitrogen ratio (MBC/MBN)</span> <span>had a great influence on the change of microbial community. Applying nitrogen fertilizer can increase the maximum value of biomass of all PLFA groups and the biomass of all PLFA groups changed in an "inverted V" shape with the increase of rest-grazing time. Besides, </span><span>instead of MBC/MBN, NO<sub>3</sub><sup>-</sup>-N</span><span> was positively affected by the biomass of</span> <span>all PLFA groups, which actively regulated the trend of microbial functions. </span></p> <p><span><strong>Conclusions</strong> </span></p> <p><span>The longer rest-grazing time is more conducive to the biomass of all PLFA groups. However, applying nitrogen fertilizer could break this pattern, namely, the 30d rest-grazing would</span> <span>be beneficial to the biomass of all PLFA groups. These findings provide key information that rest-grazing during the regreen-up period is beneficial to all PLFA groups and </span><span>fertilization could change the response of microorganisms to rest-grazing</span><span>, which provides reference measures for the restoration of degraded alpine meadows.</span></p> </div> </div>
Selection of a diversionary field and other habitats by large grazing birds in a landscape managed for agriculture and wetland biodiversity
<p>Several populations of cranes, geese, and swans are thriving and increasing in modern agricultural landscapes. Abundant populations are causing conservation conflicts, as they may affect agricultural production and biodiversity negatively. </p> <p>Management strategies involving provisioning of attractive diversionary fields where birds are tolerated can be used to reduce negative impact to growing crops. To improve such strategies, knowledge of how the birds interact with the landscape and respond to current management interventions is key.</p> <p>We used GPS locations from tagged common cranes (Grus grus) and greylag geese (Anser anser) to assess how they use and select differentially managed habitats, such as diversionary fields to decrease impact on agriculture and wetlands protected for biodiversity conservation.</p> <p>Our findings show a high probability of presence of common cranes and greylag geese in the protected area and in the diversionary field, but also on arable fields, potentially causing negative impact on agricultural production and wetland biodiversity.</p> <p>We outline recommendations for how to improve the practice of diversionary fields and complementary management to reduce risk of negative impact of large grazing birds in landscapes tailored for both conservation and conventional agriculture.</p>
Data from: Upland Sandpipers select for later time since fire and experience high nest survival in grasslands managed with patch-burn grazing
<p>Upland Sandpipers (<em>Bartramia longicauda</em>) are a grassland obligate shorebird that nests in dense vegetation structure near recently disturbed areas and could benefit from management practices that promote heterogenous vegetation structure. Although, Upland Sandpipers primary breeding range is generally managed for livestock production using traditional practices that lack patchy disturbances to facilitate higher levels of structural heterogeneity. Patch-burn grazing (PBG) could be an alternative management practice for Upland Sandpiper conservation for its ability to create areas of dense vegetation structure near recently disturbed areas. However, limited information is available regarding nest production of Upland Sandpipers within a PBG framework. To assess the compatibility of PBG with Upland Sandpiper conservation, we estimated nest site selection and survival of Upland Sandpiper nests on private lands managed with PBG in the unglaciated plains region of North Dakota. We located 59 nests from 2017–2020. Upland Sandpipers avoided 1 year since fire (YSF) patches and selected for 2 and 3 YSF patches for nest sites. Additionally, nest site selection decreased with increased bare ground and at intermediate distances to the nearest Upland Sandpiper nest. Upland Sandpipers experienced high overall nest survival during the study with 51 of 59 nests successfully hatching, which limited our ability to make inferences between daily survival rates and variables of interest. Our findings suggest that PBG can provide suitable nesting cover for Upland Sandpipers in later YSF patches despite annual prescribed fire and livestock grazing during the nesting season. PBG seems a suitable grassland management strategy that should be included in conservation planning within Upland Sandpiper's breeding distribution.</p>
Small-scale fires interact with herbivore feedbacks to create persistent grazing lawn environments
<p>Fire-herbivory feedbacks strongly influence the formation of grazing lawns in savanna ecosystems. Preliminary findings suggest that small-scale (< 25 ha) fires can engineer grazing lawns by concentrating herbivores on the post-burn green flush; however, the persistence of such grazing lawns over the longer term and without repeated fire is unknown.</p> <p>We used high-resolution Light Detection and Ranging (LiDAR) to investigate the long-term effects of fire manipulation on short grass structure (height, cover, volume, and spatial continuity) and grazing lawn establishment in Kruger National Park, South Africa. We analysed the effects of fire exclusion and experimental burns applied over a 7-year period (2013-2019) followed by a one-year cessation of burning at varying spatial scales during the early and late dry seasons.</p> <p>Fires contributed a fourfold increase in short grass cover, regardless of fire season or size. The distribution of grass height differed significantly between fire-induced grazing lawns and recently unburnt parts of the landscape where controlled fires were excluded over the experimental period. The volume (corresponding to bulk density) of short grass on the landscape responded strongly to fires, with grass volume <20 cm in height increasing with both early and late dry season fires.</p> <p>Early dry season fires caused larger and more homogeneous short grass patches. Furthermore, early dry season fires were more influential in increasing the cover of the shortest grass height class (1-5 cm).</p> <p><em>Synthesis and applications</em>. Our results demonstrate that fire-induced grazing lawns can persist over the longer-term, even when fires are no longer applied, leading to the creation of vertical and horizontal heterogeneity in the grass layer. Small-scale fires, therefore, represent a feasible management approach to expanding grazing lawn extent, potentially benefiting grazer coexistence and diversity.</p>
Can livestock grazing dampen density dependent fluctuations in wild herbivore populations?
<p>Conservation policy for the high mountains of Asia increasingly recognises the need to encompass large multi-use landscapes beyond the protected area network. Due to limited long-term research in this region, our understanding of even fundamental processes, such as factors regulating large mammal populations is poor.</p> <p>Understanding the factors that regulate animal populations, especially those generating cyclicity, is a long-standing problem in ecology. Long-term research across multiple taxa (mainly from Europe and North America) has focused on the relative roles of food and predation in generating cyclicity in population dynamics. It remains unclear how trophic interactions that are influenced by anthropogenic stressors can affect population dynamics in human-modified landscapes. </p> <p>We present a 10-year study to compare the effects of livestock grazing on density dependent dynamics in two populations of bharal, <em>Pseudois nayaur</em>, in the Himalaya. We combine this with a mechanistic understanding of whether density dependence in these two sites acts predominantly by affecting adult survival or recruitment. We compared and quantified density dependence in the bharal population by fitting Bayesian Gompertz state‐space (GSS) models.</p> <p>We found evidence for negative density dependence which indicates possible cyclic dynamics in the bharal population of the site (Tabo) with low livestock density. The population dynamics of this site were driven by recruited offspring – with a 2-year density dependent lag effect – rather than adult survival. In the site with high livestock density (Kibber), this density dependence was not detected. We postulate the potential role of excessive grazing by livestock in affecting offspring recruitment, thereby affecting the bharal population in Kibber.</p> <p><em>Synthesis and applications</em>: Our results suggest that conservation action to facilitate wild herbivore population recovery, such as the development of protected areas and village reserves, needs to account for density dependent regulation. Sites with trophy hunting require continuous monitoring to understand the effects of density dependence so that appropriate hunting quotas can be formulated.</p>
Deer grazing drove an assemblage-level evolution of plant dwarfism in an insular system
<p>Plant dwarfism, a syndrome characterised by a significant reduction in plant height and organ size, is a widely observed pattern of stress-tolerant life-form evolution that results from local adaptation to harsh environmental conditions. The drivers of assemblage-level dwarfism have primarily been attributed to abiotic factors, such as low temperature, aridity, poor soil fertility, or frequent fires. While biotic factors such as grazing pressure from herbivores can contribute to the establishment of plant dwarfism, these factors have rarely been tested at assemblage levels. Focusing on a dwarf plant assemblage comprising over 80 taxa on a small continental island in Japan with a high deer density, we hypothesised that historical deer grazing could also be a factor contributing to the large-scale convergent evolution of dwarfism. To test this hypothesis, we measured the size of 1,908 individual plants of 40 taxa-pairs, comprising both palatable and unpalatable pairs from the island and their counterpart taxa from neighbouring regions, and sought to assess which factors (i.e. low solar radiation, estimated divergence time, low nutrient conditions, and grazing pressure from deer) may have contributed to the formation of the dwarf plant assemblage on the island. We also performed genetic analysis to infer the timeframes for the establishment of dwarf taxa. Statistical analyses revealed that plant size was significantly reduced mainly among the palatable taxa growing on the island, with preferential grazing by deer being identified as the most significant factor influencing plant size. Furthermore, genetic analyses revealed that dwarf ecotypes may have evolved over tens of thousands of years.</p> <p><strong>Synthesis:</strong> To the best of our knowledge, this study is the first to demonstrate that interactions with herbivores can shape the assemblage-level convergence of plant dwarfism. These findings enhance our current understanding of the formation of plant functional diversity.</p>
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