Step Process for Selecting and Testing Surrogates and Indicators of Afrotemperate Forest Invertebrate Diversity

Abstract

BackgroundThe diversity and complexity of invertebrate communities usually result in their exclusion from conservation activities. Here we provide a step process for assessing predominantly ground-dwelling Afrotemperate forest invertebrates' (earthworms, centipedes, millipedes, ants, molluscs) potential as surrogates for conservation and indicators for monitoring. We also evaluated sampling methods (soil and litter samples, pitfall traps, active searching quadrats and tree beating) and temporal (seasonal) effects.Methodology/Principal FindingsLack of congruence of species richness across taxa indicated poor surrogacy potential for any of the focus taxa. Based on abundance and richness, seasonal stability, and ease of sampling, molluscs were the most appropriate taxon for use in monitoring of disturbance impacts. Mollusc richness was highest in March (Antipodal late summer wet season). The most effective and efficient methods were active searching quadrats and searching litter samples. We tested the effectiveness of molluscs as indicators for monitoring by contrasting species richness and community structure in burned relative to unburned forests. Both species richness and community structure changed significantly with burning. Some mollusc species (e.g. Macroptychia africana) showed marked negative responses to burning, and these species have potential for use as indicators.Conclusions/SignificanceDespite habitat type (i.e., Afrotemperate forest) being constant, species richness and community structure varied across forest patches. Therefore, in conservation planning, setting targets for coarse filter features (e.g., habitat type) requires fine filter features (e.g., localities for individual species). This is especially true for limited mobility taxa such as those studied here. Molluscs have high potential for indicators for monitoring, and this requires broader study.

Alien Terrestrial Invertebrates in South Africa

“…To date, however, no regional study has investigated the direct impact of invasive earthworms on native plant or animal communities, although some Fig. 7.2 Distribution map of alien earthworms in South Africa (map produced by R. Leihy using data from Janion-Scheepers et al 2016) invasive species have been found in native forest ecosystems (Uys et al 2010;Nxele 2012).…”

A conservation assessment of the terrestrial invertebrate fauna of Mkambati Nature Reserve in the Pondoland Centre of Endemism

“…The bee and true bug richness is likely to be higher if sampling was repeated at different times of the year, but the molluscs do not show much temporal turnover (Uys, Hamer & Slotow 2010), and the richness value for molluscs is unlikely to increase much with additional sampling.…”

South African National Survey of Arachnida (SANSA): review of current knowledge, constraints and future needs for documenting spider diversity (Arachnida: Araneae)

“…However, to date there still remains no consensus amongst researchers of the criteria for selecting appropriate surrogates, despite the attention that this topic has received in recent research (e.g. Heino & Soininen, 2007;Lovell et al, 2007;Williams et al, 2007;Uys et al, 2010). Two recent studies of invertebrates in South Africa provide useful examples of the development of surrogate use.…”