Exploring the mesofilter as a novel operational scale in conservation planning

Abstract

Summary1. Increased emphasis is being placed on developing effective biodiversity conservation tools for practical conservation planning. The mesofilter is such a biodiversity planning tool, but has yet to be fully explored to appreciate its effectiveness. The key premise of the mesofilter is that ecosystems contain certain physical elements that are specifically associated with a diversity of species. Identifying such mesofilters could therefore complement existing conservation planning tools such as coarse and fine filters. 2. To explore the value of the mesofilter as an operational scale in conservation planning, we studied 18 remnant patches of endangered montane grassland in KwaZulu-Natal, South Africa, using the physical landscape feature of patch rockiness as an abiotic surrogate for biodiversity. The objective was to determine whether the mesofilter of rockiness can predict variation in species richness and composition for three dominant grassland taxa (plants, butterflies and grasshoppers) at the landscape scale. 3. Variable levels of rockiness had significant interactions with all three focal taxa. Higher species richness of all taxa was closely associated with higher levels of rockiness in a patch. The rocky mesofilter only predicted significant differences in species composition for butterflies. Elevation was also important, possibly another mesofilter for plants and grasshoppers in this landscape. 4. Synthesis and applications. The results indicate that the use of an abiotic surrogate such as rockiness can predict biodiversity value across multiple taxa. The mesofilter is therefore a valuable surrogacy and congruency tool for practical biodiversity conservation across this landscape and would likely have similar value if explored elsewhere. It also has value in the design and management of protected areas.

Grasshopper assemblage response to surface rockiness in Afro‐montane grasslands

“…Yet, Crous et al . () found that percentage surface rock cover per se does not significantly structure grasshopper community composition in Afro‐montane grasslands. And so we hypothesised here that there may be confounding factors which could describe the observed grasshopper‐rockiness phenomenon.…”

“…This could help explain the higher species richness in higher rocky grassland sites, as observed by Crous et al . (). Lower vegetation density, a correlate of higher percentage surface rock cover, can therefore predict the presence/absence of both certain grasshopper species individually, and certain grasshopper taxonomic groups across the landscape.…”

“…Percentage surface rock exposure is known to strongly influence grasshopper species richness (Crous et al ., ) and assemblage structure in South Africa (Gebeyehu & Samways, ). Yet, Crous et al .…”

“…In the light of the results of Crous et al . (), the question then remains why species richness would be influenced by the presence of certain levels of rock exposure in this montane grassland landscape.…”

Use of ecoacoustics to determine biodiversity patterns across ecological gradients

“…At a landscape scale, this emphasizes the importance of particular natural landscape features containing special niches to maximize overall biodiversity (Crous et al. ). The grazed sites had higher acoustic diversity than either the managed sites or grassy margins.…”