Not all patches are created equal. When making priorities to conserve biodiversity given limited resources, some patches will inevitably be lost. Conventional methodology looks to rank patches individually, and then allow less important patches to be converted to other land uses so to have minimal disruption of landscape connectivity. But how realistic is it to look at patches individually when the more likely scenario involves simultaneous and/or sequential loss of multiple patches over time? This is the question Rubio and colleagues ask in their upcoming paper in Ecography. To what degree does individual patch prioritization remain valid, given that, over time, a low importance patch may become very useful for maintaining connectivity when there is the unintended loss of several surrounding patches?
Using three bird species found in Spain as their model system, the authors compare the outcome of focusing on single patch prioritization versus removal experiments that take into account the potentially synergistic impacts of multiple habitat patch losses. Their analyses focus on habitat availability (reachability) metrics and metapopulation capacity as units of comparison. They find that individual patch removal experiments do reliably select patches that are of little or no importance for sustaining connectivity. However, individual patch removal approaches fared worse in identifying high priority patches as the landscape became increasingly disturbed with multiple habitat losses. The authors suggest that instead of focusing on one patch at a time, managers should consider all possible combinations of patch loss, although they recognize the difficulty of this approach due to its computational complexity. They ultimately argue that if a landscape is likely to experience multiple losses of patches over time, it seems better if managers focus their efforts on targeting habitat patches that can be removed with the least possible negative impact on connectivity rather than trying to pinpoint the most important patches, which may not remain so in the face of substantial and additional landscape changes.
Rubio, L., Ö Bodin, L. Brotons, and S. Saura. 2015. Connectivity conservation priorities for individual patches evaluated in the present landscape: how durable and effective are they in the long term? Ecography DOI: 10.1111/ecog.00935.