Conservation Refugium Value of a Large Mesa for Grasshoppers in South Africa

Gebeyehu, Solomon; Samways, Michael J.

doi:10.1007/s10531-004-1062-8

Cited by 12 publications

(10 citation statements)

References 28 publications

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“…Samways () showed how certain montane grasshoppers occupied hilltops as thermal refugia, which demonstrated how grasshopper distribution can be significantly influenced by topography. In fact, elevation is seen as a proxy for microclimatic heterogeneity, and is a well‐known determinant of grasshopper community patterns in space (Kemp et al ., ; Samways, ; Wettstein & Schmid, ; Gebeyehu & Samways, ). Thus, grasshopper assemblages can respond to multiple environmental conditions within a landscape (Samways & Sergeev, ).…”

Section: Discussionmentioning

confidence: 99%

Grasshopper assemblage response to surface rockiness in Afro‐montane grasslands

Crous

Samways

Pryke

2013

Insect Conserv Diversity

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Grasshoppers are often an important functional component of ecosystems, and many species show high levels of endemism. Evidence exists that percentage surface rock cover within a landscape can predict diversity of grasshopper species. Nevertheless, the reason why grasshopper species are responding to rocky landscapes has not been established. Here, we explore whether grasshoppers are responding to physical rockiness per se, or rather to specific correlates of higher surface rock exposure within a landscape. We also determine if this response varies between grasshopper taxonomic groups. We sampled grasshoppers in Afro‐montane grasslands in KwaZulu‐Natal, South Africa, and recorded 10 environmental variables. We explored the influence of these variables on grasshopper community composition and grasshopper family composition. We also determined the vegetation characteristics, which significantly correlate with percentage surface rock cover in this landscape (geophyte richness, perennial grass richness and vegetation density), and then measured the similarity of species composition across these correlates. Overall, grasshopper assemblage composition, as well as familial composition, responded strongly to an elevation gradient, and not to the correlates of surface rock cover. In turn, the higher species richness in such areas is more likely a function of the significant vegetation correlates of higher surface rock cover. Across taxonomic groups, there are specialist species within each group which are associated with environmental conditions related to surface rockiness through its underlying correlates. Rock exposure across this grassland landscape is therefore an important contributor to grasshopper dispersion patterns, and has important implications for conservation planning for this taxon.

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Section: Discussionmentioning

confidence: 99%

Grasshopper assemblage response to surface rockiness in Afro‐montane grasslands

Crous

Samways

Pryke

2013

Insect Conserv Diversity

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“…Our results suggest that large‐scale alteration in vegetation patterns by wild ungulates does not directly influence the Orthoptera communities in the SNP as abundance and species diversity did not differ between the two vegetation types. We know of only three previous studies considering Orthoptera abundance in relation to wild ungulates at the landscape scale: (i) Samways and Kreuzinger (2001) found higher grasshopper densities in lightly grazed habitats compared to heavily grazed habitats, explaining the difference by increased habitat heterogeneity; (ii) Gebeyehu and Samways (2006) found that species richness and abundance decreased with altitude and grazing pressure, with concomitant changes in community composition driven by a variety of environmental factors (e.g. grass height, grass greenness, and percentage of bare soil); and (iii) Joern (2004) reported higher Orthoptera numbers under wild bison grazed – compared to ungrazed – conditions in the Konza tall‐grass prairie in Kansas (USA), explaining his findings by increased forage quality and habitat heterogeneity in grazed vegetation.…”

Section: Discussionmentioning

confidence: 99%

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

Spalinger¹,

Haynes²,

Schütz³

et al. 2011

Insect Conserv Diversity

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1. Grasslands cover approximately 40% of the Earth's terrestrial landscape, supporting large communities of vertebrate and invertebrate herbivores. Orthoptera play an important role, consuming relatively large amounts of biomass. Their occurrence can be strongly affected by habitat diversity and structure, which can be shaped by large herbivores. Several studies have focused on the impact of livestock on Orthoptera communities, but little is known about how wild ungulates influence the abundance and diversity of these insects in grassland ecosystems.2. We studied Orthoptera abundance and diversity in subalpine grasslands in the Swiss Alps, where grazing by red deer and chamois has created a mosaic of shortand tall-grass patches. Data on vegetation structure, habitat diversity and plant nitrogen (N) content allowed us to consider how these parameters affected the occurrence of Orthoptera at our study sites.3. We found a total of nine Orthoptera species with an average density of 2.6 individuals m )2 . Neither Orthoptera abundance nor diversity differed between shortand tall-grass patches created by large ungulates. Both Orthoptera abundance and diversity were, however, positively influenced by increasing vegetation height, but negatively by increasing habitat diversity within patches. Increasing plant N content promoted a more even spread of species within the insect assemblage on short-but not on tall-grass patches.4. Large-scale habitat alteration by wild ungulates had no direct effect on the abundance and diversity of Orthoptera. However, we observed that they indirectly affected Orthoptera abundance and diversity by altering plant N content and the structure of the habitat at small scales.

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“…A large mesa in South Africa acted as a refuge for Orthoptera in comparison to the heavily grazed flatlands which surrounded it (Gebeyehu and Samways 2006). The summit, which was inaccessible to grazing livestock, was an important conservation refuge for one grasshopper species, Orthochtha dasycnemis.…”

Section: The Effect Of Grazingmentioning

confidence: 99%

Grazing and Orthoptera: a review

Gardiner¹

2018

JOR

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Orthoptera are an important biological component of grasslands as a crucial link in the food chain. Grazing, either by wild animals or livestock for human food production, exerts considerable influence on the Orthoptera of grasslands. For example, grazing prevents succession of open grasslands to scrub and forest, creates heterogeneity in sward height, and provides patches of bare earth through the action of livestock hooves breaking the vegetative cover. Grazing may also interact with other forms of grassland management such as burning to produce quite complex interactions which vary greatly between regions and Orthoptera species. Threats to grassland Orthoptera include overgrazing; conversely, abandonment of grazing can lead to the loss of open habitats vital to many species. It is important to have ungrazed areas to provide refuges for species negatively affected by grazing. Rotational management -moving domestic livestock between different pastures -will also allow a range of sward structures to develop over a landscape. The over-arching principle for grazing management should be to establish a heterogeneous sward with a range of sward heights and bare earth for oviposition/basking. In more extensive systems, patches of scrub can form habitat of woody vegetation for species such as bush crickets. The greatest diversity of habitats should provide the highest species richness.

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Conservation Refugium Value of a Large Mesa for Grasshoppers in South Africa

Cited by 12 publications

References 28 publications

Grasshopper assemblage response to surface rockiness in Afro‐montane grasslands

Grasshopper assemblage response to surface rockiness in Afro‐montane grasslands

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

Grazing and Orthoptera: a review

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