Grasshopper assemblage response to surface rockiness in Afro‐montane grasslands

Abstract

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.

Is cattle grazing more important than landscape heterogeneity for grasshoppers in Afromontane grassland?

“…In the temperate Cape Floristic Region in South Africa, behavior of small, endemic Betiscoides species was influenced by wind intensity, temperature and vegetation height (Matenaar et al 2014). We argue that rocky outcrops might add to the heterogeneity of microclimatic niches available in the landscape, directly by providing shelter and basking sites, and indirectly by altering the vegetation layer (Crous et al 2014).…”

Temporal Patterns of Ant Diversity across a Mountain with Climatically Contrasting Aspects in the Tropics of Africa

“…Their role in the study of richness patterns might also provide a predictive framework for the response of diversity to climate change [ 19 ]. An understanding of drivers of diversity along these gradients also identifies useful environmental filters for conservation initiatives [ 20 ]. Macro-ecological studies of species richness in mountains have documented the role of the mid-domain effect [ 21 ], temperature [ 22 , 23 ], energy, and available area [ 24 ].…”

Construction of a GeogDetector-based model system to indicate the potential occurrence of grasshoppers in Inner Mongolia steppe habitats

“…A number of qualitative studies have explored these relationships and grasshopper habitat suitability since the 1970s. In quantitative studies, statistical methods are used to determine whether a habitat factor or interactions among factors contribute significantly to grasshopper abundance, such as correlation analysis, significance test, and multivariate ordination techniques (Torrusio et al , 2002; Sirin et al , 2010; Bazelet & Samways, 2011 a , b ; Cease et al , 2012; Ebeling et al , 2013; Crous et al , 2014). Zhou et al (2012) used geostatistics and Kriging interpolation to obtain the spatial pattern of grasshoppers and vegetation characteristics and their spatial correlations.…”