Balancing biodiversity and agriculture
Modern agriculture has revolutionised the planet’s capacity to support humans, yet has simultaneously had a greater negative impact on biodiversity than any other human activity. Balancing the demand for food with the conservation of biodiversity is one of the most pressing issues of our time. While these concerns are relevant globally, there is an urgent need to conduct research of this nature in the developing world, characterised by high population growth rates and rapid agricultural development. This project focuses on providing the evidence to underpin better planning of production landscapes to offset the negative effects of agriculture on biodiversity in southern Africa. Post-doc Chevonne Reynolds is tackling this question in collaboration with Claire Spottiswoode, Res Altwegg of the Statistics in Ecology, Environment and Conservation group in the Department of Statistical Sciences, and Andrew Balmford of the University of Cambridge.
Is a land-sharing or a land-sparing strategy best for conserving southern African birds? These two strategies represent alternatives whereby conservation and production are integrated in space (“land-sharing”) or separated in space (“land-sparing”). Advocates of land-sparing suggest that although land-sharing is beneficial within farmland, if it reduces yield then a larger area must be farmed to meet any given production target. However, the merits of each strategy are still hotly debated, in part because this question is typically addressed by short-term field studies that ignore processes relevant to biodiversity occurring at longer and larger scales.
Making use of the remarkable South African Bird Atlas Project (SABAP2) dataset, Chevonne is assessing how agricultural land-use patterns affect bird populations, and ultimately which strategy is best suited to the conservation of southern Africa’s bird diversity. SABAP2 is a citizen science initiative collecting information about bird occurrence at a 9 x 7 km resolution. Over 16 000 checklists have been submitted thus far, generating an excellent time series dataset, which is further complemented by fine-resolution land-use data for the region. Chevonne is currently investigating how farmland configuration within a 9 x 7 km grid cell predicts the population density of individual bird species using occupancy models. She is conducting the analysis across three separate biomes in South Africa to determine whether bird populations respond in a consistent way across different regions and therefore whether results can be extrapolated to other landscapes. We hope to extend this analysis to determine whether particular ecological and life-history traits predict a bird species’ response to agricultural intensification, further adding to the development of a generalizable framework. At the time of writing, Chevonne was nearing completion on the first stages of the data analysis. Although still in its early days, we anticipate that the results will provide useful insights for conservation planners, farmers and policy makers on how to improve management for biodiversity in production landscapes.
Chevonne is also collaborating with researchers at the University of Florida and the University of Swaziland to investigate how landscape heterogeneity in agricultural mosaics affects biodiversity. A key feature of the developing world is that agriculture is typically interspersed among other land-uses, creating heterogeneous landscapes. While there is evidence that landscape heterogeneity positively influences biodiversity, the application of this hypothesis is hindered by a lack of understanding of which components of landscape heterogeneity drive these effects, and at what spatial scale(s). We also need to know whether diverse taxonomic groups are similarly affected before we can apply this hypothesis as a general conservation strategy in agricultural mosaics. Chevonne led a team of international students to collect data on several taxonomic groups in the savanna-sugarcane mosaics of north-eastern Swaziland in June and July 2016. Using a priori identified independent gradients of compositional and configurational landscape heterogeneity, they tested how bird, dung beetle, ant and meso-carnivore diversity responded across different spatial scales. They found that biodiversity responds to landscape composition, but that the responses differ across taxonomic groups in their magnitude, direction and scale. This suggests that one-size-fits-all conservation strategies will not address the challenge of protecting biodiversity in agricultural landscapes, and that diverse, multi-scale strategies are of paramount importance.
Activities in 2016
- Chevonne Reynolds joined the project as a Post-doctoral researcher and made large strides in refining analysis techniques and preparing the land-use data.
- Further collaboration between the Fitz and the Statistics in Ecology, Environment and Conservation (SEEC) research group.
- Teaching and training of Swazi and U. Florida students on field and research techniques.
- Two papers resulting from Chevonne’s team’s research in Swaziland, one led by an undergraduate student, are in review with Journal of Applied Ecology and Diversity Distributions, with an additional two papers in preparation.