Underproductive agriculture aids connectivity in tropical forests

Abstract

Establishing connectivity in tropical lowland forests is a major conservation challenge, particularly in areas dominated by agriculture. Replanting schemes have been widely utilized as a method for reconnecting once contiguous forest patches. However, these approaches require funds for both initial planting and subsequent site maintenance. Furthermore, identifying sites for habitat rehabilitation schemes is difficult and may require purchasing of land, sometimes at great expense. Underproductive, often unprofitable, areas of agriculture have the potential to aid in re-establishing forest connectivity via natural forest regeneration. We identified an area of natural forest regrowth, previously cleared for agriculture and abandoned due to high levels of flooding. We assessed the structural regrowth of this forest after a 17-year period, and examined its efficacy as corridor habitat for Bornean elephants. Regrowth areas had re-established tree canopy areas similar to that of adjacent forest, as well as a randomly selected site of uncleared forest. Flooding in the area hampered the regrowth of some sections of the site; however, ∼79% of the site exhibited canopy coverage. Aboveground carbon levels have returned to 50% those of uncleared forests, with flooding resulting in areas of reduced vegetation regeneration. Elephants have shown increasing usage of the regenerated forest, suggesting that the area has regenerated its suitability as elephant corridor habitat. We have shown that what would traditionally be thought of as low-quality, flood-prone areas for habitat restoration can be a useful, cost-effective tool for wildlife corridor management. We propose that natural regeneration of reclaimable, underproductive agriculture has the potential to play a key role in lowland tropical forest connectivity, reconnecting now isolated populations of endangered Bornean elephants.