Impact of wild ungulate grazing on Orthoptera abundance and diversity in subalpine grasslands

Spalinger, Lena C.; Haynes, Alan G.; Schütz, Martin; Risch, Anita C.

doi:10.1111/j.1752-4598.2011.00180.x

Cited by 27 publications

(27 citation statements)

References 40 publications

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“…Conversely, the positive relationship of another group of herbivores-grasshoppers-to grazing is consistent with other grazing studies in these meadows (Holmquist et al 2010;2013) and elsewhere (Bock et al 2006;Cease et al 2012;Fartmann et al 2012). Although vertebrate grazers are herbivorous competitors, many grasshoppers prefer grazed areas with a) reduced canopy and litter, and b) increased bare ground, because access to bare ground facilitates soil oviposition, and the warmer ground resulting from reductions in cover likely speeds development (Huntly and Inouye 1988;Fartmann et al 2012; but see Spalinger et al 2011). …”

Section: Discussionsupporting

confidence: 71%

Equine Grazing in Managed Subalpine Wetlands: Effects on Arthropods and Plant Structure as a Function of Habitat

Holmquist

Schmidt-Gengenbach

Haultain

2013

Environmental Management

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Grazing management necessarily emphasizes the most spatially extensive vegetation assemblages, but landscapes are mosaics, often with more mesic vegetation types embedded within a matrix of drier vegetation. Our primary objective was to contrast effects of equine grazing on both subalpine vegetation structure and associated arthropods in a drier reed grass (Calamagrostis muiriana) dominated habitat versus a wetter, more productive sedge habitat (Carex utriculata). A second objective was to compare reed grass and sedge as habitats for fauna, irrespective of grazing. All work was done in Sequoia National Park (California, USA), where detailed, long-term records of stock management were available. We sampled paired grazed and control wet meadows that contained both habitats. There were moderate negative effects of grazing on vegetation, and effects were greater in sedge than in reed grass.Conversely, negative grazing effects on arthropods, albeit limited, were greater in the drier reed grass, possibly due to microhabitat differences. The differing effects on plants and animals as a function of habitat emphasize the importance of considering both flora and fauna, as well as multiple habitat types, when making management decisions. Sedge supported twice the overall arthropod abundance of reed grass as well as greater diversity; hemipteran and dipteran taxa were particularly abundant in sedge. Given the greater grazing effects on sedge vegetation, greater habitat provision for terrestrial arthropods, and value as aquatic arthropod habitat, the wetter sedge assemblage is worthy of additional consideration by managers when planning for grazing and other aspects of land usage.

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Section: Discussionsupporting

confidence: 71%

Equine Grazing in Managed Subalpine Wetlands: Effects on Arthropods and Plant Structure as a Function of Habitat

Holmquist

Schmidt-Gengenbach

Haultain

2013

Environmental Management

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“…It is known that these invertebrates only consume 20-30% of the plant biomass removed (Bailey andRiegert 1973, Ingrisch andKo¨hler 1998), while the rest is ''dropped'' to the ground and is directly entering the soil food-web. In addition, Belovsky and Slade (2000) showed that increasing grasshopper densities lead to increases in soil N cycling, and Spalinger et al (2012) found increased grasshopper abundance with increasing FIG. 2.…”

Section: Aboveground Vertebrate and Invertebrate Herbivore Impact On mentioning

confidence: 99%

Aboveground vertebrate and invertebrate herbivore impact on net N mineralization in subalpine grasslands

Risch

Schütz

Vandegehuchte

et al. 2015

Ecology

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Abstract. Aboveground herbivores have strong effects on grassland nitrogen (N) cycling. They can accelerate or slow down soil net N mineralization depending on ecosystem productivity and grazing intensity. Yet, most studies only consider either ungulates or invertebrate herbivores, but not the combined effect of several functionally different vertebrate and invertebrate herbivore species or guilds. We assessed how a diverse herbivore community affects net N mineralization in subalpine grasslands. By using size-selective fences, we progressively excluded large, medium, and small mammals, as well as invertebrates from two vegetation types, and assessed how the exclosure types (ET) affected net N mineralization. The two vegetation types differed in long-term management (centuries), forage quality, and grazing history and intensity. To gain a more mechanistic understanding of how herbivores affect net N mineralization, we linked mineralization to soil abiotic (temperature; moisture; NO 3 À , NH 4 þ , and total inorganic N concentrations/pools; C, N, P concentrations; pH; bulk density), soil biotic (microbial biomass; abundance of collembolans, mites, and nematodes) and plant (shoot and root biomass; consumption; plant C, N, and fiber content; plant N pool) properties.Net N mineralization differed between ET, but not between vegetation types. Thus, shortterm changes in herbivore community composition and, therefore, in grazing intensity had a stronger effect on net N mineralization than long-term management and grazing history. We found highest N mineralization values when only invertebrates were present, suggesting that mammals had a negative effect on net N mineralization. Of the variables included in our analyses, only mite abundance and aboveground plant biomass explained variation in net N mineralization among ET. Abundances of both mites and leaf-sucking invertebrates were positively correlated with aboveground plant biomass, and biomass increased with progressive exclusion. The negative impact of mammals on net N mineralization may be related partially to (1) differences in the amount of plant material (litter) returned to the belowground subsystem, which induced a positive bottom-up effect on mite abundance, and (2) alterations in the amount and/or distribution of dung, urine, and food waste. Thus, our results clearly show that short-term alterations of the aboveground herbivore community can strongly impact nutrient cycling within ecosystems independent of long-term management and grazing history.

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“…This indicates that butterflies are well conserved in both types of ENs sampled here. The response of grasshoppers to the presence of wild grazers here is more surprising, as other studies in Europe and Africa have shown that they are not much influenced by the type of grazer [32,33]. This is most likely due to a greater variety in the types of grazing in the wild grazed area, creating more niche opportunities, or this might be due to differential grazer intensities between the two ENs [17].…”

Section: Discussionmentioning

confidence: 62%

“…and so need grazing to maintain their diversity and function within grasslands [30,31]. Yet, grasshopper diversity seems to show little change when livestock grazing is compared to that of wild ungulates [32,33], with the disturbances caused by livestock grazing seemingly mimicking those of wild ungulate grazing. Butterflies on the other hand are more sensitive to the presence of grazers in general [3].…”

Section: Introductionmentioning

confidence: 99%

Wild Herbivore Grazing Enhances Insect Diversity over Livestock Grazing in an African Grassland System

2016

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Southern Africa’s grassland biodiversity is threatened by habitat transformation such as commercial forestry. Ecological networks (ENs) have been instigated to alleviate the pressure of habitat transformation on local biodiversity. ENs are large scale webs of corridors and patches of natural vegetation criss-crossing production landscapes that can simulate conditions in protected areas (PAs). Many ENs have lost many native large mammal species, which have been replaced by domestic livestock to retain natural grazing dynamics, which could have an impact on the long-term value of ENs for insects. Here we compared dung beetle, butterfly and grasshopper diversity in ENs across a landscape mosaic of timber plantations, where 1) wild megaherbivores were maintained, 2) in ENs where these herbivores were replaced by livestock and, 3) in a nearby World Heritage PA which retained its natural complement of megaherbivores. Sites in the PA far from any plantation were similar in composition to those in the wild grazed EN. Presence of the wild grazers improved the alpha- and beta-diversity of all focal insect taxa when compared to domestic grazing. Furthermore, species composition shows significant differences between the two grazing systems indicating that an assemblage of native large mammals facilitates insect diversity conservation. We support the maintenance or introduction of large native mammals in ENs or similar conservation areas in production landscapes to simulate the ecological conditions and natural heterogeneity in nearby PAs.

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Impact of wild ungulate grazing on Orthoptera abundance and diversity in subalpine grasslands

Cited by 27 publications

References 40 publications

Equine Grazing in Managed Subalpine Wetlands: Effects on Arthropods and Plant Structure as a Function of Habitat

Equine Grazing in Managed Subalpine Wetlands: Effects on Arthropods and Plant Structure as a Function of Habitat

Aboveground vertebrate and invertebrate herbivore impact on net N mineralization in subalpine grasslands

Wild Herbivore Grazing Enhances Insect Diversity over Livestock Grazing in an African Grassland System

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