Ecological Restoration at Scale

Abstract

In the age of Biodiversity Hotspots, ecological restoration at a landscape scale often provides the only avenue to successfully achieving our conservation goals. However, the resources needed to protect endangered ecosystems are limited. Here, we add four incremental advances in our understanding of how restoration strategies can be scaled up to play a meaningful global role in biodiversity conservation without incurring prohibitive costs. We explore several questions related to large-scale tropical forest restoration, using Area de Conservacion Guanacaste (ACG), in Costa Rica as a case study. First, we ask how successful has the largely passive restoration strategy (centered on wildfire prevention) been for restoring ACG dry forest, and what factors underpin the variation in forest recovery? Second, can organic waste disposal be harnessed as a restoration strategy for tropical forests? Third, how does second-growth forest heterogeneity translate into differential occupancy of regenerating habitat by large terrestrial vertebrates? Finally, moving beyond tropical forests, we look at how a passive restoration approach could be deployed in a deep-water marine context, asking where it would be most effective.

The results of these research projects paint a picture of major opportunities to achieve significant conservation gains without breaking the proverbial bank. When soil conditions are favorable, fire management in ACG has been sufficient deliver canopy closure in less than 30 years. Further, when environmental conditions are not conducive to forest recovery, application of low-cost organic wastes seems to offer a powerful tool for promoting passive forest recovery. We find that overall, the value of second-growth forest for terrestrial vertebrates is high, and all threatened and endangered terrestrial vertebrates in ACG utilize young forest. Dndangered Baird’s tapirs are more frequently encountered in second-growth forest habitat than old growth forest. These lessons on the high but variable value of passive forest restoration methods offers a guide of sorts for how policymakers could prioritize the passive restoration of other habitats. Turning this thinking to the high seas reveals that eliminating international fishing in just 25% of its extent would likely protect more than 50% of the high seas’ total productivity.