Abstract
Biogeography has a critical influence on how ecological communities
respond to threats and how effective conservation interventions are
designed. For example, the resilience of ecological communities is
linked to environmental and climatic features, and the nature of threats
impacting ecosystems also varies geographically. Understanding
community-level threat responses may be most accurate at fine spatial
scales, however collecting detailed ecological data at such a high
resolution would be prohibitively resource intensive. In this study, we
aim to find the spatial scale that could best capture variation in
community-level threat responses whilst keeping data collection
requirements feasible. Using a database of biodiversity records with
extensive global coverage, we modelled species richness and total
abundance (the responses) across land-use types (reflecting threats),
considering three different spatial scales: biomes, biogeographical
realms, and regional biomes (the interaction between realm and biome).
We then modelled data from three highly sampled biomes separately to ask
how responses to threat differ between regional biomes and taxonomic
group. We found strong support for regional biomes in explaining
variation in species richness and total abundance compared to biomes or
realms alone. Our biome case studies demonstrate that there is a high
variation in magnitude and direction of threat responses across both
regional biomes and taxonomic group, but all groups in tropical forest
showed a consistently negative response, whilst many taxon-regional
biome groups showed no clear response to threat in temperate forest and
tropical grassland. Our results suggest that the taxon-regional biome
unit has potential as a reasonable spatial and ecological scale for
understanding how ecological communities respond to threats and
designing effective conservation interventions to bend the curve on
biodiversity loss.