Efficacy of Low and High Complexity Vegetation Treatments for Reestablishing Terrestrial Arthropod Assemblages during Montane Wetland Restoration

Assessments of faunal reassembly during wetland restorations have typically been derived from relatively benign, lower‐elevation environments. We investigated recovery of terrestrial arthropod assemblages in conjunction with restoration of a montane wet meadow in Sequoia National Park (Sierra Nevada, California, U.S.A.). Our goal was to assess response of arthropod assemblages to wetland restoration in this winter‐dominated environment, including comparison of faunal reassembly in (1) areas of sparse plugs (planted over several years) and (2) dual‐density plantings with additional heterogeneity, complexity, and connectance to source habitats provided by high‐density bands running through sparsely planted habitat (final study year only). Results across all restoration treatments indicated varying levels of faunal reassembly, but convergence of faunal assemblages with reference habitat had not occurred after recovery periods as long as 5 years. Similarity indices and multivariate compositional results indicated a slower recovery than did univariate trends for assemblage metrics and abundances for some individual taxa, highlighting the utility of assessments using a range of taxa and analytical approaches. Faunal recovery did not appear to lag behind that of vegetation structure, despite the short growing season. The dual‐density plantings indicated faster recovery after 1 year, across almost all metrics, than was observed after several years for the sparse plantings. Restoration configurations that increase habitat complexity, heterogeneity, and/or connectance may disproportionately increase rates of passive faunal reassembly and prove to be cost‐effective approaches for promoting recovery of ecosystem function.     

Relative impacts of cattle grazing and feral animals on an Australian arid zone reptile and small mammal assemblage

The effect of different levels of cattle grazing on an arid Australian small terrestrial mammal and lizard assemblage was assessed in a long‐tem series of cross‐fence comparisons. Cross‐fenced sites were closely matched for edaphic and vegetation characteristics and experienced near identical weather patterns, to ensure that cattle grazing pressure was the principal determinant of any differences in fauna assemblages. In addition, the effects of removal of cattle, cats, foxes and rabbits from three of these long‐term monitoring sites were assessed to determine the relative impacts of cattle grazing and feral animals. Small mammal captures, with the exception of Mus musculus, revealed a significant negative response to cattle grazing pressure but this response was of a considerably lower magnitude than the dramatic increase in rodent captures and species richness within the feral animal‐proof Arid Recovery Reserve. Higher kangaroo numbers in ungrazed controls, compared with treatments grazed by cattle, possibly negated the benefits to small mammals of removing cattle grazing. No reptile species responded significantly to the grazing treatments although reptile richness and captures of geckos and skinks were the lowest and agamid captures were the highest at heavily grazed sites. Nephrurus levis was the only reptile species to increase significantly, while captures of some smaller geckoes declined, within the feral‐proof treatment. Feral predation exerted a more significant effect on most small mammal species than the levels of cattle grazing assessed in this study, yet reptile responses to grazing or feral animals were less apparent and were likely primarily driven by changes in vegetation cover or secondary trophic impacts.     

Vegetation changes following sheep grazing in abandoned mountain meadows

Abstract. Sheep grazing was investigated as an alternative to traditional management of meadows in the Krkono?e Mts. Until the second World War these meadows were mown in mid‐summer and grazed by cattle for the rest of the season. Subsequent abandonment of the meadows has resulted in decreasing species richness. Degradation phases of the former communities have been replacing the original species‐rich vegetation. Significant changes were apparent six years after the introduction of sheep grazing. In grazed plots the proportion of dominant herbs (Polygonum bistorta and Hypericum maculatum) decreased and grasses (Deschampsia cespitosa, Festuca rubra, Agrostis capillaris, Anthoxanthum alpinum) increased. The increase in grasses was positively correlated with an increase in several herbs. The proportion of some herbs increased despite being selectively grazed (Adenostyles alliariae, Melandrium rubrum, Veratrum lobelianum). Any losses caused by grazing of mature plants were probably compensated by successful seedling establishment. Cessation of grazing resulted in significant changes in vegetation within three years. The cover of nitrophilous tall herbs and grasses (e.g. Rumex alpestris, Holcus mollis, Deschampsia cespitosa, Geranium sylvaticum) increased in the abandoned plots. In the plots grazed for nine years cover of species‐rich mountain meadow species increased (e.g. fine‐leaved grasses, Campanula bohemica, Potentilla aurea, Viola lutea, Silene vulgaris). The main conservation risk is the expansion of a competitive species with low palatability, Deschampsia cespitosa. This species can be suppressed by a combination of grazing and mowing. In order for grazing to be effective, the number of sheep should be proportional to meadow production. This may be difficult to maintain as production is variable and is impossible to predict at the beginning of a growing season. A large part of the biomass may thus remain intact in some years. Negative effects of grazing may be, at least partly, eliminated by a combination of cutting and grazing.     

生长季放牧对高寒草甸传粉网络的影响

植物-传粉者相互作用面临人类活动的威胁。在青藏高原地区,放牧是一项主要的人类活动干扰,过度放牧导致高寒草甸植被严重退化。然而在该区域放牧如何影响植物-传粉者相互作用网络还不得而知。在青藏高原东部的高寒草甸选取了两个研究样点,每个样点包括一块禁牧样地（生长季禁牧）和放牧样地（全年放牧）。在2016年至2018年每年的生长季（7月和8月）进行了连续3年观测,共构建16个传粉网络。结果发现,在研究区域的高寒草甸生态系统中,传粉者群落的物种组成以双翅目昆虫为主。放牧后双翅目、鳞翅目以及鞘翅目传粉者的种类数减少,但膜翅目传粉者的种类数未受到放牧的影响。放牧干扰显著降低了群落中植物、传粉者以及它们之间相互作用的多样性,但对传粉网络的嵌套性和特化程度（H₂''）没有显著影响,说明网络的稳定性和恢复力没有受到放牧的影响。探讨了放牧对传粉网络的影响,发现区域放牧强度过大,降低了传粉昆虫和传粉网络的多样性。未来需要进一步深入研究高寒草甸生态系统中放牧强度对传粉网络的影响模式,以期为合理的放牧制度模式提供理论依据。     

Long-term fencing improved soil properties and soil organic carbon storage in an alpine swamp meadow of western China

Overgrazing significantly affects alpine meadows in ways similar to grasslands in other areas. Fencing to exclude grazers is one of the main management practices used to protect alpine meadows. However, it is not known if fencing can improve soil properties and soil organic carbon storage by restraining grazing in alpine meadows. We studied the long-term (nine-year) effects of fencing on soil properties, soil organic carbon and nitrogen storage compared with continued grazing in an alpine swamp meadow of the Qinghai–Tibetan Plateau, NW China. Our results showed that fencing significantly improved vegetation cover and aboveground biomass. There were significant effects of fencing on pH value, soil bulk density, and soil moisture. Long-term fencing favored the increase of soil total nitrogen, soil organic matter, soil organic carbon, soil microbial biomass carbon and soil carbon storage compared with grazed meadows. Our study suggests that long-term fencing to prevent disturbance could greatly affect soil organic carbon and nitrogen storage with regard to grazed meadows. Therefore, it is apparent from this study that fencing is an effective restoration approach of with regard to the soil’s storage ability for carbon and nitrogen in alpine meadow of the Qinghai–Tibetan Plateau.     

Moderate grazing increased alpine meadow soils bacterial abundance and diversity index on the Tibetan Plateau

The response of grassland soil bacterial community characteristics to different grazing intensities is central ecological topics. However, the underlying mechanisms between bacterial abundance, diversity index, and grazing intensity remain unclear. We measured alpine meadow soil bacterial gene richness and diversity index under four grazing intensities using 16S rDNA sequence analysis on the Tibetan Plateau. The results suggest that extreme grazing significantly decreased alpine meadow both bacterial gene abundance and diversity index (p < .05). The lowest operational taxonomic unit numbers were 3,012 ± 447 copies under heavy grazing in the growing season. It was significantly lower than heavy grazing with approximately 3,958 ± 119 copies (p < .05). The Shannon index for medium and high grazing grassland bacterial diversity was slightly higher than for light grazing in the growing season. Furthermore, the lowest index was approximately 9.20 ± 0.50 for extreme grazing of grassland in the growing season. The average bacterial gene abundance and diversity index in the dormancy period were slightly higher than that in the growing season. Soil bulk density, pH, ammonium, and nitrate nitrogen were the main positive factors driving grazed grassland bacterial communities. Our study provides insight into the response of alpine meadows to grazing intensity, demonstrating that moderate grazing increases bacterial community diversity in grazed grasslands.     

Predicted macroinvertebrate response to water diversion from a montane stream using two-dimensional hydrodynamic models and zero flow approximation

We used two-dimensional hydrodynamic models for the assessment of water diversion effects on benthic macroinvertebrates and associated habitat in a montane stream in Yosemite National Park, Sierra Nevada Mountains, CA, USA. We sampled the macroinvertebrate assemblage via Surber sampling, recorded detailed measurements of bed topography and flow, and coupled a two-dimensional hydrodynamic model with macroinvertebrate indicators to assess habitat across a range of low flows in 2010 and representative past years. We also made zero flow approximations to assess response of fauna to extreme conditions. The fauna of this montane reach had a higher percentage of Ephemeroptera, Plecoptera, and Trichoptera (%EPT) than might be expected given the relatively low faunal diversity of the study reach. The modeled responses of wetted area and area-weighted macroinvertebrate metrics to decreasing discharge indicated precipitous declines in metrics as flows approached zero. Changes in area-weighted metrics closely approximated patterns observed for wetted area, i.e., area-weighted invertebrate metrics contributed relatively little additional information above that yielded by wetted area alone. Loss of habitat area in this montane stream appears to be a greater threat than reductions in velocity and depth or changes in substrate, and the modeled patterns observed across years support this conclusion. Our models suggest that step function losses of wetted area may begin when discharge in the Merced falls to 0.02 m³/s; proportionally reducing diversions when this threshold is reached will likely reduce impacts in low flow years.     

Impact of reindeer grazing on ground-dwelling Carabidae and Curculionidae assemblages in Lapland

Reindeer Rangifer tarandus L. grazing shapes forest vegetation, microclimate, and soil respiration in Lapland, especially due to grazing on lichens (Cladina). We studied how these changes and their magnitude affect ground‐dwelling species of beetle families Carabidae (predators) and Curculionidae (herbivores), by using pitfall traps to collect invertebrates from pairs of grazed and ungrazed study plots over a wide range of site types. Changes in abundance, composition, richness and diversity of beetle assemblage were tested in relation to magnitude of the impacts on vegetation. The species compositions of Carabidae and Curculionidae differed between grazed and ungrazed plots in all sites. The relative difference between grazed and ungrazed plots in the number of individuals increased linearly with the impact of reindeer on vegetation cover. Carabid beetles, as a family, were more common in grazed plots in all sites. Curculionid beetles were more common in ungrazed plots in the birch dominated sites. This difference was mainly due to the species that feeds on deciduous leaves. In the pine dominated sites with high Cladina cover and more changes in ground vegetation, the number of curculionids feeding on conifers was higher in grazed plots. Species richness and diversity (H’) of both families were higher in grazed plots. Of the total 27 species, 11 were found only in grazed plots, while not a single species was found only in ungrazed plots. The relative difference between plots in diversity and evennes (H’/H'max) had humped response to the difference in Cladina cover. The diversity values were greater in grazed plots at the intermediate levels of grazing impact, and only in sites with very low or extremely high Cladina cover difference was the diversity higher in ungrazed plots. The response of beetle diversity resembled the hypotheses suggested for the relationship between grazing and vegetation diversity: greatest positive effect at intermediate grazing intensity and negative effects at unproductive sites.     

Effects of livestock breed and grazing pressure on ground‐dwelling arthropods in Cantabrian heathlands

Abstract 1. The effects of different goat breeds and grazing pressures on epigeal arachnids (Lycosidae and Opiliones) and ground beetles (Carabidae) were assessed in a heath–gorse shrubland located in the north of the Iberian Peninsula. Three treatments (low grazing pressure with Cashmere breed, high grazing pressure with Cashmere breed, and high grazing pressure with local Celtiberic breed) with three replicates of each treatment were allocated randomly to nine plots. 2. Arthropod fauna abundance, diversity, and species richness were estimated using pitfall trapping over 3 years (2003, 2004, and 2005). Vegetation cover, composition, and height were assessed along transects and above‐ground plant biomass was sampled in quadrats. 3. Lower grazing pressure led to lower herbaceous cover and higher heather cover than high grazing pressure. Overall, it did not enhance arthropod diversity or abundance, but the abundance and species richness of carabids, and abundance of lycosids like Pardosa pullata, were higher under high stocking rates, whereas Opiliones were favoured by the low stocking rates. Although it has been assumed that traditional breeds enhance biodiversity, the present study found no significant differences for both arthropod fauna and vegetation between the goat breeds. 4. Arthropod–vegetation relationships were examined by constrained ordination. Fauna assemblages followed a gradient from closed canopy shrubland areas, in the lowest grazing pressure, to grassier open canopy areas resulting from higher grazing pressure, revealing the importance of grazing management as a driver of arthropod community structure of the heathland.     

Effect of fencing and grazing on a Kobresia-dominated meadow in the Qinghai-Tibetan Plateau

Grazing is one of the most important factors influencing community structure and productivity in natural grasslands. Fencing to exclude grazers is one of the main management practices used to protect grasslands. Can fencing improve grassland community status by restraining grazing? We conducted a field community study and indoor soil analyses to determine the long-term effects of fencing and grazing on the above-ground community and soil in a Kobresia-dominated meadow in the Qinghai-Tibetan Plateau, NW China. Our results showed that fencing significantly improved above-ground vegetation productivity but reduced plant density and species diversity. Long-term fencing favored the improvement of forage grass functional groups and restrained the development noxious weed functional groups. There were significant positive effects of fencing on below-ground organic matter, total nitrogen, available nitrogen, total phosphorus and available phosphorus. The productivity of grazed meadow showed a weak decrease over time. There were long-term decreasing trends for plant density both in fenced and grazed meadows. Our study suggests that grazing can be considered as a useful management practice to improve species diversity and plant density in long-term fenced grasslands and that periodic grazing and fencing is beneficial in grassland management.     

Using ants to manage sustainable grazing: Dynamics of ant faunas along sheep grazing gradients conform to four global patterns

Ants are considered an important faunal group for the functioning of arid rangelands, they have a long history of use for environmental monitoring, and exhibit four global patterns in grazing lands: (i) soil and vegetation type are primary determinants of ant community composition, and have a far greater effect on ant community composition than grazing; (ii) grazing induces species compositional change, but does not necessarily affect species richness or abundance; (iii) a species response to grazing is not necessarily consistent across habitats; and (iv) approximately one‐quarter to one‐half of species that are common enough for statistical analysis have significant responses to grazing. Here we report the patterns of arid zone ant faunas as they exist after several decades of sheep grazing in southern Australia, and examine the extent to which they conform to the four global patterns. We measured ant faunas along grazing gradients (varying distance to water) in seven paddocks containing two soil and two vegetation types on five pastoral properties. Total site abundance and richness of ants did not differ significantly with distance from water, but the abundance of 10 (34%) of the 29 most common species did differ; three were increasers, three were decreasers, and four had mixed responses dependent on soil/vegetation type. Rare species showed no trend with grazing intensity. The ant fauna of the more structurally complex vegetation types appeared to be the most vulnerable to grazing effects. Multivariate analysis showed soil type was the primary factor influencing ant faunal composition, followed by vegetation structure; however, grazing treatment effects were present. This study fully supports the recently identified global patterns of ant responses to grazing. It also shows that sampling regional ant faunas using widely dispersed traps can detect ant faunal patterns comparable to studies that use smaller‐scale grids of traps.     

Mediating Water Temperature Increases Due to Livestock and Global Change in High Elevation Meadow Streams of the Golden Trout Wilderness

Rising temperatures due to climate change are pushing the thermal limits of many species, but how climate warming interacts with other anthropogenic disturbances such as land use remains poorly understood. To understand the interactive effects of climate warming and livestock grazing on water temperature in three high elevation meadow streams in the Golden Trout Wilderness, California, we measured riparian vegetation and monitored water temperature in three meadow streams between 2008 and 2013, including two “resting” meadows and one meadow that is partially grazed. All three meadows have been subject to grazing by cattle and sheep since the 1800s and their streams are home to the imperiled California golden trout (Oncorhynchus mykiss aguabonita). In 1991, a livestock exclosure was constructed in one of the meadows (Mulkey), leaving a portion of stream ungrazed to minimize the negative effects of cattle. In 2001, cattle were removed completely from two other meadows (Big Whitney and Ramshaw), which have been in a “resting” state since that time. Inside the livestock exclosure in Mulkey, we found that riverbank vegetation was both larger and denser than outside the exclosure where cattle were present, resulting in more shaded waters and cooler maximal temperatures inside the exclosure. In addition, between meadows comparisons showed that water temperatures were cooler in the ungrazed meadows compared to the grazed area in the partially grazed meadow. Finally, we found that predicted temperatures under different global warming scenarios were likely to be higher in presence of livestock grazing. Our results highlight that land use can interact with climate change to worsen the local thermal conditions for taxa on the edge and that protecting riparian vegetation is likely to increase the resiliency of these ecosystems to climate change.     

Effects of livestock exclusion on in‐stream habitat and benthic invertebrate assemblages in montane streams

1. Stream and riparian ecosystems in arid montane areas, like the interior western United States, are often just narrow mesic strands, but support diverse and productive habitats. Meadows along many such streams have long been used for rangeland grazing, and, while impacts to riparian areas are relatively well known, the effect of livestock grazing on aquatic life in streams has received less attention. 2. Attempts to link grazing impacts to disturbance have been hindered by the lack of spatial and temporal replication. In this study, we compared channel features and benthic macroinvertebrate communities (i) between 16 stream reaches on two grazed allotments and between 22 reaches on two allotments where livestock had been completely removed for 4 years, (ii) before and after the 4‐year grazing respite at a subset of eight sites and (iii) inside and outside of small‐scale fenced grazing exclosures (eight pairings; 10+ year exclosures) in the meadows of the Golden Trout Wilderness, California (U.S.A.). 3. We evaluated grazing disturbance at the reach scale in terms of the effects of livestock trampling on per cent bank erosion and found that macroinvertebrate richness metrics were negatively correlated with bank erosion, while the percentage of tolerant taxa increased. 4. All macroinvertebrate richness metrics were significantly lower in grazed areas. Bank angle, temperature, fine sediment cover and erosion were higher in grazed areas, while riparian cover was lower. Regression models identified riparian cover, in‐stream substratum, bank conditions and bankfull width‐to‐depth ratios as the most important for explaining variability in macroinvertebrate richness metrics. 5. Small‐scale grazing exclosures showed no improvements for in‐stream communities and only moderate positive effects on riparian vegetation. In contrast, metrics of macroinvertebrate richness increased significantly after a 4‐year period of no grazing. 6. The success of grazing removal reported here suggests that short‐term removal of livestock at the larger, allotment meadow spatial scale is more effective than long‐term, but small‐scale, local riparian area fencing, and yields promising results in achieving stream channel, riparian and aquatic biological recovery.     

Response of vertebrates to fenceline contrasts in grazing intensity in semi‐arid woodlands of eastern Australia

Abstract Changes in the abundance, species richness and assemblage composition of vertebrates due to grazing by domestic stock were investigated in the semi‐arid woodlands of eastern Australia. Analyses were based on the differences found at 10 fenceline contrast sites. Two species of amphibians, 22 species of reptiles and two species of small mammal were captured in pit traps during the surveys. Kangaroos (red and eastern grey), sheep, goats and 66 species of birds were recorded along line transects. Analyses revealed that abundance of diurnal reptiles and species richness of diurnal reptiles and birds were significantly lower on heavily grazed sites than they were on lightly grazed sites. At a local scale, the gecko, Gehyra variegata, was more abundant where grazing was heavier, while Diplodactylus conspicillatus, Diplodactylus steindachneri and Rhynchoedura ornata responded to variables indirectly related to grazing intensity (kangaroo density, sheep and goat dung mass and sheep density, respectively). Birds more commonly sighted on lightly grazed areas than heavily grazed areas were the apostlebird, brown treecreeper, crested bellbird, grey butcherbird, hooded robin, jacky winter, little woodswallow, Australian magpie‐lark, mulga parrot, splendid wren, white‐browed treecreeper and yellow‐rumped thornbill. Birds more commonly sighted on heavily grazed areas than on lightly grazed areas were the Australian raven and chestnut‐crowned babbler. Most variation in species composition between sites was due to spatial separation and no regional‐level indicator species of grazing were evident. A combination of direct grazing‐related changes (e.g. loss of ground cover) and indirect effects of the pastoral industry (e.g. introduction of artificial sources of water) lead to changes in fauna at different scales of analysis across regions.     

Spider biodiversity potential of an ungrazed and a grazed inland salt meadow in the National Park 'Neusiedler See-Seewinkel' (Austria): implications for management (Arachnida: Araneae)

To assess the biodiversity potential of an ungrazed and a grazed inland salt meadow in the Seewinkel (Eastern Austria), spider assemblages were recorded by pitfall trapping for 1 year. Both species assemblages consisted, to a large extent, of rare species of conservation interest. The species assemblage of the grazed site was dominated by Pardosa agrestis, but highly specific halotopobiontic species also occurred in higher numbers. Halotolerant species were also present in the ungrazed meadow, but their individual number was much lower. The species composition of this site reflects the more balanced microclimatical situation of the high sward. Comparison of the two assemblages with 207 other meadow spider assemblages of Central Europe shows a separated position, especially of the grazed site assemblage. High similarities with assemblages of meadows with a similar vegetation structure indicate a high importance of management. Considering the high proportion of rare species on both sites, the best management of the salt meadow and pan shores of the Seewinkel should combine areas of light grazing with ungrazed areas. However, the proportion of these parts and the intensity of grazing still remains to be determined by quantitative experiments.     

Plant competition,abiotic, and long- and short-term effects of large herbivores on demography of opportunistic species in a semiarid grassland

Summary The emergence and subsequent survival and growth of five opportunistic weeds were monitored after seed additions to long-term grazing treatments with or without current-year grazing, long-term ungrazed treatments, and removal treatments designed to eliminate plant competition from existing perennials while either leaving vegetation and soil structure unaltered or disturbed. The treatments were applied on both uplands and lowlands to assess the relative influence of macroabiotic environment versus plant competition. The long-term effects of large herbivores on the initial emergence of seedlings were greater than the effects of removing competition. Very few individuals emerged on the long-term grazed treatments that were either grazed or ungrazed during the experiment. Numbers of individuals emerging on the long-term ungrazed treatments were greater or equal to those emerging on the no-competition-undisturbed treatments, but numbers were greatest on no-competition-disturbed treatments. None of the seeded individuals on the long-term grazed, currently grazed treatments survived to the end of the growing season. There was a slightly greater end-of-season biomass of seeded species and percentage of the total population reaching reproductive status on the long-term ungrazed compared with grazed-nondefoliated treatments, and very high survival, biomass, and proportions of reproductives on both no-competition treatments. Cover types in the immediate vicinity of seedlings influenced both germination and survival, but the effects differed between species and treatments. Equal compensation to current-year herbivory occurred on long-term heavily grazed treatments even though above-ground production was much greater on long-term protected sites. Productivity varied with topography, but very few topographic main effects or interactions occurred with demographic variables of seeded species, suggesting that macroabiotic effects were of minor importance compared with grazing and plant competition.     

Insensitivity of Soil Microbial Activity to Temporal Variation in Soil N in Subarctic Tundra: Evidence from Responses to Large Migratory Grazers

Large migratory grazers commonly influence soil processes in tundra ecosystems. However, the extent to which grazing effects are limited to intensive grazing periods associated with migration has not previously been investigated. We analyzed seasonal patterns in soil nitrogen (N), microbial respiration and extracellular enzyme activities (EEAs) in a lightly grazed tundra and a heavily grazed tundra that has been subjected to intensive grazing during reindeer (Rangifer tarandus L.) migration for the past 50 years. We hypothesized that due to the fertilizing effect of the reindeer, microbial respiration and EEAs related to microbial C acquisition should be higher in heavily grazed areas compared to lightly grazed areas and that the effects of grazing should be strongest during reindeer migration. Reindeer migration caused a dramatic peak in soil N availability, but in contrast to our predictions, the effect of grazing was more or less constant over the growing season and the seasonal patterns of microbial activities and microbial N were strikingly uniform between the lightly and heavily grazed areas. Microbial respiration and the EEAs of β-glucosidase, acid-phosphatase, and leucine-aminopeptidase were higher, whereas that of N-acetylglucosamidase was lower in the heavily grazed area. Experimental fertilization had no effect on EEAs related to C acquisition at either level of grazing intensity. Our findings suggest that soil microbial activities were independent of grazing-induced temporal variation in soil N availability. Instead, the effect of grazing on soil microbial activities appeared to be mediated by substrate availability for soil microorganisms. Following a shift in the dominant vegetation in response to grazing from dwarf shrubs to graminoids, the effect of grazing on soil processes is no longer sensitive to temporal grazing patterns; rather, grazers exert a consistent positive effect on the soil microbial potential for soil C decomposition.     

Cattle grazing, raptor abundance and small mammal communities in Mediterranean grasslands

Abundance and diversity of small mammals are usually affected strongly by grazing either due to decreased food availability or quality, decreased suitability of soil for building burrow systems due to trampling and/or due to increased predation risk in the structurally simpler grazed areas. We estimated the effects of grazing-induced changes in vegetation and soil and of increased predation on small mammals in a Mediterranean grassland landscape. We measured vegetation structure, soil compaction and small mammal abundance and species composition in 22 plots of 8 Sherman live traps each, arranged according to an unbalanced two-way ANOVA design with two grazing levels (grazed areas and cattle exclosures) and two predator abundance levels (increased densities of Eurasian kestrels Falco tinnunculus by means of nest boxes and control). Plots were sampled during 2 consecutive years in early summer and early fall. Exclosure from cattle increased significantly vegetation height and volume and decreased soil compaction. Grazing-induced changes in vegetation height and volume and in soil compaction produced strong effects on small mammal abundance and species richness. Increased kestrel densities did not have significant additive or interactive effects, with the effects of grazing-induced vegetation and soil gradients on abundance or richness of small mammals. Our results suggest that the effects of grazing on small mammal communities in Mediterranean montane grasslands were mainly due to reduced food availability and by negative effects of trampling on the suitability of soils for building burrow systems. Decreased food quality and increased predation in grazed areas seemed to play a minor role, if any. Reductions in stock densities would then favor generalist predator populations in Mediterranean grasslands through the expected positive effects of such reductions on the availability of food and burrows for small mammals.     

Diversity and trait composition of moths respond to land-use intensification in grasslands: generalists replace specialists

Grasslands belong to the ecologically most relevant habitats in cultural landscapes, but also provide high economic value when used as meadows or pastures. Land-use intensification in grasslands negatively affects plant diversity as well as arthropod communities that depend on plants as food source and habitat, with important consequences for the provision and resilience of ecosystem functioning. In this study, we sampled grassland moth species and investigated whether species composition, diversity and life-history trait characteristics of moth communities respond to the type and intensity of land use, comparing 26 sites in three different regions of Germany. Consistent across the three regions, we found that pastures grazed by cattle, horses or sheep harbour fundamentally different moth communities than meadows (mown and fertilized grasslands). Overall land-use intensity (LUI)—i.e., grazing intensity, amount of fertilizer applied and mowing frequency taken together—significantly reduced abundance and species richness as well as diversity. Some 27.6% of the species showed significant negative responses to LUI. A shift towards generalist life-history traits was observed: in frequently mown and fertilized meadows, rare specialist species were replaced by ubiquist species, i.e., highly reproductive habitat generalists. These results show the sensitivity of moths, an important group of arthropod herbivores and pollinators, to land use change in grassland ecosystems. The functional homogenization of life-history traits in plants along land-use gradients is mirrored by their herbivore consumers, leaving high-intensity grasslands less diverse and potentially less resilient to environmental disturbances.     

Differential Indirect Effects of Excluding Livestock and Rabbits from Chalk Heath on the Associated Leafhopper (Hemiptera: Auchenorrhyncha) Fauna

Preliminary results are presented of sampling the leafhopper assemblages on a field experiment designed to examine the differential effects of rabbits and livestock (mainly sheep) on the vegetation of chalk heath in southern England. Experimental plots that excluded livestock either allowed entry by rabbits or excluded them. Results were compared with those from plots grazed by both livestock and rabbits. After 7 years, exclusion of grazing herbivores had resulted in predictable increases in vegetation height, but no major changes were detected in the species composition of the vegetation. As expected, ungrazed plots had higher species richness and greater abundances of several individual leafhopper species. However, plots grazed only by rabbits had a leafhopper assemblage that was distinct from either ungrazed or mixed grazing plots. It is suggested that rabbit grazing may have subtle effects on grassland invertebrate assemblages that are not necessarily predictable from an examination of the species composition of the vegetation. Chalk heath vegetation contains an unusual mixture of calcicole and calcifuge plant species, but the leafhopper assemblage included a restricted number of calcareous grassland specialist species and only one species strongly associated with acidic grasslands; most leafhoppers recorded were generalist grassland species.