New PollinERA publication proposes a process-based way to predict biodiversity capacity

What if two agricultural landscapes looked identical in terms of the biodiversity they currently support, but had very different potential for biodiversity in the future? And what if the same management action could produce very different results depending on where it was applied

These are some of the questions explored in a new PollinERA paper, ‘Functional Trait Capacity: from observing biodiversity to predicting landscape capacity’, published in the open-access journal npj Sustainable Agriculture.

Biodiversity monitoring tells us which species are present in a landscape and how they change over time. Policy and land management, however, rarely rely on direct observation of individual farms or sites. They rely instead on habitat classifications used as proxies. Each habitat type is given a score, and the scores are used to predict how much biodiversity a site supports and how a management change will affect it. England's statutory biodiversity metric, used for Biodiversity Net Gain, works in this way: it uses habitat as a proxy for biodiversity, scoring habitats by their intrinsic distinctiveness and current condition. A 2024 evaluation across 24 sites found that the metric's scores correlated with most plant biodiversity measures but with none of the bird or butterfly measures tested (Marshall et al., 2024). 

Habitat proxies have a further limitation. Two landscapes with the same habitats, or the same recorded species, can differ considerably in what they could support. The same intervention, such as converting part of the cropland to semi-natural habitat, can produce very different outcomes depending on the surrounding landscape.1 

The paper introduces Functional Trait Capacity (FTC) to address this gap. FTC is intended to measure the range of ecological strategies a landscape can sustain, given its physical structure, its management, its ecological conditions and a stated time horizon. FTC estimates this capacity from ecological processes, rather than inferring it from habitat labels or from the species recorded so far. 

In the near term, FTC could complement existing monitoring by linking what is observed today with what a landscape could sustain in future. In the longer term, if it holds up under empirical testing, it could offer a process-based alternative to habitat-proxy metrics for assessing management scenarios and policy options. The authors, including PollinERA coordinator Prof. Christopher J. Topping, emphasise that further empirical work is needed. The illustrative profiles and virtual strategies used in the paper's demonstration need to be replaced with evidence for specific taxa and regions.

Read the full paper here.

Reference

Marshall, C.A.M. et al. (2024). England's statutory biodiversity metric enhances plant, but not bird nor butterfly, biodiversity. Journal of Applied Ecology. https://doi.org/10.1111/1365-2664.14697