Unprecedented rates of species extinction present a serious challenge in the field of conservation biology. Although protected areas are considered to be key tools to preserve vital habitat for threatened species, increasing the amount of protected land does not necessarily result in more effective protection for biodiversity. Manipulation of the surrounding landscape outside of protected areas (‘buffer zones’) has the potential to affect ecosystem processes that occur inside of their boundaries and, ultimately, their ecological integrity. The installment of the Convention on Biological Diversity’s Aichi Biodiversity Target to increase the amount of protected land worldwide calls for a global assessment of the conservation performance of long-established protected areas.
Such a task, however, highlights a lack of global, long-term biological datasets. Under development by the Group on Earth Observations – Biodiversity Observation Network (GEO BON), satellite-remote-sensing essential biodiversity variables (SRS-EBVs) seek to fill this biodiversity data gap. Using time series data of SRS-EBVs, we hypothesized that if long-established protected areas are efficient conservation tools, then (1) SRS-EBVs will remain approximately stable through time inside of protected areas, and (2) change in SRS-EBVs observed in buffer zones will not influence the state of SRS-EBVs within protected areas.
Results/Conclusions
Four SRS-EBVs were selected to represent a variety of ecosystem structure and function metrics, including (1) the total area of natural land cover, (2) FPAR (fraction of photosynthetically active radiation), (3) the number of fire ignitions and (4) the number of days a fire burned. While all SRS-EBVs remained stable through time inside of the global network of protected areas (slopes ≈ 0), these relationships were influenced by factors including in which continent a protected area was located and to what management type a protected area was subject. Conversely, change in SRS-EBVs that occurred in buffer zones significantly influenced change inside of protected areas (i.e. as FPAR, the number of fires and the duration of fires changed in buffers, the same occurred inside of protected areas). The amount of natural land cover was an exception to this pattern; it remained constant inside protected areas despite the change in total natural land cover that occurred in buffers. These results indicate that the efficacy of protected areas varies geographically and suggests a need to reconsider the managerial practices of protected areas and their surrounding landscapes if they are expected to serve as efficient safe havens for biodiversity and to ensure the persistence of species.