Forests and agroforestry as overlapping hotspots of woody species diversity and above-ground carbon storage in a Costa Rican landscape: a remote sensing analysis

Tropical land-use change strongly affects biological diversity and carbon cycling at multiple spatial levels. Evidence for synergies between ecosystem services (ES), such as carbon storage and biodiversity, has been accumulating for natural and managed ecosystems in the tropics and subtropics, and at a global scale. Less research has examined ES across different land-use types at a landscape-level, which is the most relevant for applied conservation and management. Agroforestry systems (AFS) offer opportunities to harbor synergies between carbon storage and species diversity, reducing the impact of the larger agricultural sector on the global climate system. This study maps the distribution and spatial overlap of hotspots of above-ground carbon (AGC) storage and woody species diversity across forests and AFS in the western Central Valley of Costa Rica. Metrics for woody species diversity included species richness and Shannon’s diversity index (Shannon’s H). The diversity-AGC relationship was assessed across land-uses using field plot data, remote sensing imagery, and a geostatistical hotspot analysis within a 178 km 2 subsection of the Río Grande basin. Areas with co-occurring significant spatial clusters of high diversity and AGC values were identified to locate ES synergies in the study area. Of the three land-use types examined (forests, pasture, and coffee AFS), the study found that forests were of highest conservation priority, with over a third of forested areas yielding ES synergies. AFS also provided synergies, though at lower rates. Shannon’s H was more applicable than species richness for observed diversity-AGC relationships in human-modified landscapes. Agroforestry practices provide opportunities to actively promote functional diversity in line with farmers’ management goals while increasing connectivity within the fragmented landscape. Forest conservation combined with AFS management to maximize landscape-scale ES synergies is concluded to be the most effective strategy for integrated biodiversity conservation and climate change mitigation.