Why adding habitat can destabilize species coexistence - consequences to restoration

In the context of the looming biodiversity crisis, adding patches of habitat has been proposed as a restoration strategy in several ecosystems. However, these interventions rarely mimic the conditions of the natural habitats precisely. Consequently, not all species equally benefit from the restored habitat, fostering a difference in species fitness. Using a metapopulation model with a competition-colonization trade-off, we explore how the introduction of habitat patches where the competition ability of the superior competitor is either enhanced or diminished affects species coexistence. We show that adding habitat changes the coexistence regime at the regional scale, potentially leading to undesired consequences. Our results suggest that inferior competitors with colonization rates close to the lower bound that enables coexistence are particularly vulnerable to this kind of intervention. The impact on the coexistence regime is also dependent on the amount of habitat restored as well as the extent to which the new habitat distorts the competitive capacity of the superior competitor. Our results highlight the double-edged sword effect of suboptimal restoration, revealing potential unintended consequences that could exacerbate biodiversity loss. On the other hand, restoration favoring endangered species is also identified as a conservation tool. The present study advances in the mechanistic comprehension of habitat restoration, a necessary endeavor in the face of the challenges posed by global change.