In order to understand how land-use change impacts biodiversity, different dimensions of biodiversity and environmental factors – aspects like climate, competition, landscape structure, and nutrient levels – should be considered. Two measurable dimensions of biodiversity include taxonomic diversity and functional diversity. Taxonomic diversity refers to the number of species (commonly measured as species richness), whereas functional diversity looks at patterns of functional traits (such as body size, habitat preference, or food source).
van Schalkwyk, J., Gaigher, R., Pryke, J.S. and Samways, M.J. 2021. Within‐corridor heterogeneity is more important than corridor design for maintaining butterfly functional and taxonomic diversity. Journal of Applied Ecology. DOI: 10.1111/1365-2664.14006.
Recent research investigated the impact of landscape heterogeneity, or a measure of variability/complexity of landscapes at both the temporal and spatial scales, on butterfly functional and taxonomic diversity. Researchers sampled butterflies at 36 sites within conservation corridors that are located at a commercial timber estate, and which constitute part of large-scale Ecological Networks in South Africa. Half of the hundreds of hectares were unplanted and form connected corridors composed of remnant grasslands with Afromontane Mistbelt Forest interspersed. Previous work has looked at the impact of landscape heterogeneity on taxonomic diversity; however, this doesn’t account for the effect of land-use change that can be seen through interspecific variation. This study used functional traits to fill that gap.
The aim of this research was to better understand the effect of vegetation structure at the landscape scale – i.e. landscape heterogeneity – on butterfly populations in corridors. Another goal was to examine the influence of landscape heterogeneity (the number and frequency of different patch types, which includes both the composition and arrangement of patches) at different spatial resolutions for conservation planning.
The analysis found that within-corridor heterogeneity is more important for taxonomic and functional diversity than corridor design at the landscape scale. These findings suggest that:
- Management goals should be a balance between increasing taxonomic diversity and functional diversity
- Landscape complexity (vegetation structure at a local scale) should be considered in addition to corridor design (broad scale)
- Corridors should be as wide as possible to increase patch size
In order to maintain butterfly diversity, management plans should consider the spatial configuration of sites on both ends of the fire frequency continuum in landscapes. The sites of these extremes should be touching to reduce negative edge effects. More research is needed to better understand how traits not included in this study, such as butterfly flight speed, interact with landscape quality and corridor size.
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