Habitat connectivity buffers extinction under extreme droughts in experimental metapopulations

Abstract

Connectivity maintains the spatial dynamics of metapopulations by promoting dispersal between habitat patches, potentially buffering populations and communities against continued global change. However, this function is threatened by habitats becoming increasingly fragmented, and habitat matrices becoming increasingly inhospitable, potentially reducing the resilience and persistence of populations. Yet, we lack a clear understanding of how reduced connectivity interacts with rates of environmental change to destabilise populations. Using laboratory microcosms containing metapopulations of the Collembola Folsomia candida, we investigate the impact of habitat connectivity on metapopulation persistence under a range of simulated droughts, a key stressor for this species. We manipulated both drought severity and the number of patches affected by drought across landscapes connected by either good or poor-quality corridors. We measured the time of population extinction, the maximum rate of population decline, and the variability of abundance among patches as criteria to evaluate the persistence ability of metapopulations. We show that whilst drought severity and number of drought-affected patches negatively influenced population persistence, these results were mitigated by increased habitat connectivity, which increased population persistence time and decreased both how fast populations declined and the variability in abundance among patches. Our results suggest that enhancing spatial connectivity can increase the persistence of metapopulations, increasing the time available for conservation actions to take effect, and/or for species to adapt or move in the face of continued stress. Given that fragmentation increases the isolation of habitats, improving habitat connectivity by using good quality corridors may provide a useful strategy to enhance the resistance of spatially structured populations.

Exposure of protected areas in Central America to extreme weather events

“…In the context of our study region, the metrics revealed zones of overexposure that require preemptive measures, such as restoration of the Amazon and Orinoco forests to maintain thermal refugia or management of the Mesoamerican corridor to protect ecosystems from tropical cyclones during the dry season. Similarly, metrics can reveal areas with low overexposure (Figure 4) that play an important role as biodiversity corridors and offer microhabitats that buffer against extreme drought and heat wave effects (González‐del‐Pliego et al., 2020; Li et al., 2023; Scheffers et al., 2014). Although these metrics might not capture the full complexity of species’ responses to climate change (Dawson et al., 2011; Foden et al., 2007), their assessment often aligns with results of more sophisticated species–climate response modeling assessments (Garcia et al., 2016).…”