DOI: 10.7291/d1px04
title: Bird Frugivore Abundance data from: Applied nucleation facilitates tropical forest recovery

description: Applied nucleation, mostly based upon planting tree islands, has been
 proposed as a cost‐effective strategy to meet ambitious global forest and
 landscape restoration targets. We review results from a 15‐year study,
 replicated at 15 sites in southern Costa Rica, that compares applied
 nucleation to natural regeneration and mixed‐species tree plantations as
 strategies to restore tropical forest. We have collected data on planted
 tree survival and growth, woody vegetation recruitment and structure, seed
 rain, litterfall, epiphytes, birds, bats and leaf litter arthropods. Our
 results indicate that applied nucleation and plantation restoration
 strategies are similarly effective in enhancing the recovery of most
 floral and faunal groups, vegetation structure and ecosystem functions, as
 compared to natural regeneration. Seed dispersal and woody recruitment are
 higher in applied nucleation and plantation than natural regeneration
 treatments; canopy cover has increased substantially in both natural
 regeneration and applied nucleation treatments; and mortality of planted
 N‐fixing tree species has increased in recent years. These trends have led
 to rapid changes in vegetation composition and structure and nutrient
 cycling. The applied nucleation strategy is cheaper than mixed‐species
 tree plantations, but there may be social obstacles to implementing this
 technique in agricultural landscapes, such as perceptions that the land is
 not being used productively. Applied nucleation is likely to be most
 effective in cases where: planted vegetation nuclei enhance seed dispersal
 and seedling establishment of other species; the spread of nuclei is not
 strongly inhibited by abiotic or biotic factors; and the approach is
 compatible with restoration goals and landowner preferences. Synthesis and
 applications. Results from our 15‐year, multi‐site study show that applied
 nucleation can be a cost‐effective strategy for facilitating tropical
 forest regeneration that holds promise for helping to meet large‐scale
 international forest restoration commitments.
description: We sampled bird communities in 11 restoration sites and 5 mature
 forests in southern Costa Rica (Coto Brus County). Restoration sites were
 located between Las Cruces and the town of Agua Buena (8° 44' N, 82°
 56' W). Study sites were 1100-1400 m a.s.l., and the dominant natural
 ecosystem was premontane moist forest. Precipitation across the study
 areas varies with microtopography but is ~4 m y-1 at Las Cruces. Mean
 annual temperature at Las Cruces is 21° C. Eleven
 restoration sites were established on degraded agricultural land in
 2004-2006. Each site included three 50 x 50 m plots (N = 33 plots), which
 were cleared of vegetation and randomly assigned to one of three
 treatments. Controls were abandoned to regenerate naturally; islands
 (i.e., applied nucleation treatments) were planted with patches of trees
 including two each of 4 x 4, 8 x 8, and 12 x 12 m patches; and plantations
 were planted with rows of seedlings across the entire plot. These local
 restoration treatments spanned a gradient of intervention intensity;
 seedling density (seedlings ha-1) was zero for controls, 86 for islands,
 and 313 for plantations. Seedlings planted in islands and plantations were
 a mix of two native timber species, Terminalia amazonica (J.F. Gmel.)
 Exell (Combretaceae) and Vochysia guatemalensis Donn. Sm. (Vochysiaceae),
 and two naturalized legumes, Erythrina poeppigiana Walp. Skeels and Inga
 edulis Mart. (Fabaceae). All plots were cleared with machetes for 2.5
 years to allow planted seedlings to grow above existing grasses and forbs.
 Treatments had been in place for 10-12 y when bird counts took place at
 which time there were already large differences in vegetation structure
 and composition between treatments. Detailed descriptions of the
 restoration treatments and tree species selection are provided elsewhere
 (Cole et al. 2010). Birds in restoration sites were
 surveyed by J.A.R. in Mar-Apr, Jul-Aug, and Nov-Dec 2016. Each
 experimental plot at each site was actively searched in a random order for
 20 min per observation, and all frugivorous birds seen or heard within the
 plot were recorded. Birds flying over the site without using it were
 excluded from analyses. Bird taxonomy follows the American Ornithologists’
 Union Checklist of the Birds of North America and its supplements
 (American Ornithologists' Union 1998).