Ecological networks act as extensions of protected areas for arthropod biodiversity conservation

Abstract

Summary1. Landscape-scale ecological networks (ENs) are composed of linear corridors and are widely used to mitigate the adverse effects of intensive land use. One drawback with ENs used for conservation is that being small or linear they result in more edge relative to interior than would be the case naturally. Furthermore, there is little evidence to date that ENs do conserve indigenous biodiversity. 2. Here, we use five arthropod taxa at many sites over two geographical areas within South Africa with different elevations and grassland types to test the conservation value of remnant grassland ENs in a plantation forestry context. In particular, the relative value of arthropod biodiversity in exotic plantation blocks, their edges and the interiors of ENs among the plantations were compared with those in neighbouring protected areas (PAs). We use the effects that the plantation blocks have on the adjacent PAs as a reference for comparing the ENs among the plantations. Arthropods were selected to represent biodiversity, as they are small, diverse, habitat sensitive, resource dependent, ecologically important and can be sampled in large numbers. 3. In total, 10 422 individuals from 244 species were sampled. Importantly, there were no significant differences in species richness, abundance or assemblage composition between EN interior zones and PA interior zones in both geographical areas. 4. Using earlier established edge zones of 32 m, we found that plantation blocks had the lowest species richness and abundance compared with either grassland edge zones (<32 m from the edge) or grassland interior zones ( ‡ 32 m from the edge). 5. Synthesis and applications. Ecological networks are established to conserve biodiversity in areas of intensive land use. Provided that ecological networks are wide enough (i.e. >64 m) to overcome edge effects, they can support similar levels and quality of arthropod biodiversity as protected areas. Remnant grassland ecological networks in agroforestry can provide natural finger-like extensions from neighbouring protected areas and therefore have conservation value.

Anthropogenic impacts in protected areas: assessing the efficiency of conservation efforts using Mediterranean ant communities

“…This sampling that was done nearly one decade ago also provides a baseline for future re-sampling in order to detect the possible changes in ant communities driven by global change. Although the use of multiple and complementary surrogates to assess the state of biodiversity should be chosen when possible (Sattler et al, 2013; Lentini & Wintle, 2015), we think our analyses are valid because some of our results lead to similar conclusions as studies on other species (e.g., Crist, Wilmer & Aplet, 2005; Pryke & Samways, 2012; Villard & Metzger, 2014; Rayner et al, 2015; Wood et al, 2015). Revealing the patterns that impact the efficiency of PAs networks for biodiversity conservation, our results can inform management decisions and influence the prioritization of conservation efforts.…”

“…Studies using different taxa have recently showed similar results; for example, bird diversity has been showed to respond to distance to PA boundary (Ikin et al, 2014; Wood et al, 2015; Rayner et al, 2015). More generally, several authors have recently stressed the importance of fragmentation, landscape configuration and the maintenance of native biodiversity on lands adjacent to protected areas (Crist, Wilmer & Aplet, 2005; Pryke & Samways, 2012; Villard & Metzger, 2014). …”

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

“…In a study of edge effects on arthropods, Pryke & Samways (2012b) also found little difference in spider species richness across a series of transects covering pine plantations, natural forests and grassland in the KwaZulu-Natal midlands, but found variable patterns in a broader-scale survey at sites in the midlands and northern KwaZulu-Natal (Pryke & Samways, 2012c).…”

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

“…ENs effectively conserve many insect and plant species [8,9]. In the design of ENs, edge effects need to be taken into consideration as the effectiveness of corridors is determined by the size of the edge effect [10].…”