Tropical secondary forest enrichment using giant stakes of keystone figs

Abstract

Developing rapid, cost-effective, methods to facilitate forest recovery in degraded tropical habitats is a key restoration goal. Here, we evaluated the efficacy of establishing large (≥2 m) vegetative cuttings or stakes of Ficus (Moraceae), keystone species that play essential roles in ecological food webs. We evaluated eight species with broad geographic distribution in the Neotropics in three separate studies in southern Costa Rica: (1) a common garden trial; (2) a multi-site study; and (3) an earlier 2004 study. In the two recent trials, resprouting and survival ranged from 0 to 100%. Six species of hemiepiphytic figs (subgenus Urostigma) resprouted at much higher rates (80–100%) compared to free-standing species in the subgenus Pharmacosycea (0–18%). Contrary to expectations, resprouting did not vary by wood specific gravity. Mean canopy area for established species was 1.1–1.4 m2 after 2 yr, diameter growth at this stage was negligible, and one species developed fruit (∼12% of individuals). In the older resurvey, surviving stakes (60%) had mean DBH of 13.7 ± 6.2 cm with canopy height of 8.1 ± 2.7 m after 13 yr; 50% of individuals were fruiting when surveyed during peak dry season. There was no mortality in the 9 yr lapse since they were last surveyed. Results indicate that this methodology shows promise and could be used to establish enrichment plantings in degraded habitats that augment fruit availability, and thereby facilitate recovery.