Summary1. Developing restoration strategies that accelerate natural successional processes and are resource-efficient is critical to facilitating tropical forest recovery across millions of hectares of deforested lands in the tropics. 2. We compared tree recruitment after a decade in three restoration treatments (natural regeneration, applied nucleation/island tree planting and plantation) and nearby reference forest in the premontane rain forest zone in southern Costa Rica. The study was replicated at 13 sites with a range of surrounding forest cover, enabling us to evaluate the relative influence of local restoration treatments and landscape forest cover on tree recruitment. 3. Density of small-seeded (<5 mm), animal-dispersed recruits was lower in natural regeneration than in applied nucleation, plantation or reference forest plots. Species richness, species density and density of medium (5-10 mm)-and large (>10 mm)-seeded, animal-dispersed recruits were greatest in reference forest, intermediate in applied nucleation and plantation and lowest in natural regeneration plots. 4. Recruit composition differed substantially between reference forest and all restoration treatments. In general, plantation recruit composition was more similar to reference forests and natural regeneration least similar; however, there was high within-treatment variation. 5. Models suggested weak support for the effect of surrounding forest cover on tropical tree recruit density and composition, as compared to restoration treatment and site conditions (e.g. elevation), in this intermediate forest cover landscape. 6. Synthesis and applications. Applied nucleation appears to be a cost-effective strategy as compared to plantation-style planting to accelerate tropical forest recovery regardless of the amount of forest cover immediately adjacent to the site. However, even with active restoration interventions, forest recovery is a multidecade process that proceeds at highly variable rates.

1. 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. 2. 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.

Tropical agriculture is a major driver of biodiversity loss, yet it can provide conservation opportunities, especially where protected areas are inadequate. To investigate the long-term biodiversity capacity of agricultural countryside, we quantified bird population trends in Costa Rica by mist netting 57,255 birds of 265 species between 1999 and 2010 in sun coffee plantations, riparian corridors, secondary forests, forest fragments, and primary forest reserves. More bird populations (69) were declining than were stable (39) or increasing (4). Declines were common in resident, insectivorous, and more specialized species. There was no relationship between the species richness of a habitat and its conservation value. High-value forest bird communities were characterized by their distinct species composition and habitat and dietary functional signatures. While 49% of bird species preferred forest to coffee, 39% preferred coffee to forest and 12% used both habitats, indicating that coffee plantations have some conservation value. Coffee plantations, although lacking most of the forest specialists, hosted 185 bird species, had the highest capture rates, and supported increasing numbers of some forest species. Coffee plantations with higher tree cover (7% vs. 13%) had more species with increasing capture rates, twice as many forest specialists, and half as many nonforest species. Costa Rican countryside habitats, especially those with greater tree cover, host many bird species and are critical for connecting bird populations in forest remnants. Diversified agricultural landscapes can enhance the biodiversity capacity of tropical countryside, but, for the long-term persistence of all forest bird species, large (>1,000 ha) protected areas are essential. avian ecology | ecosystem services | global change | ornithology | tropical biology

Questions: Natural regeneration is increasingly recognized as a potentially costeffective strategy to reach ambitious forest landscape restoration targets, but rates of recovery are notoriously variable. We asked how well initial habitat conditions after cessation of agriculture predict forest recovery after nearly a decade. We aimed to provide land managers with general rules of thumb to assess when it is necessary to invest resources in active restoration, such as tree planting, to accelerate forest recovery.Location: Coto Brus County, Puntarenas, Costa Rica. Methods:We compiled data on initial vegetation structure, soil nutrients, prior landuse history and surrounding forest cover at 13 sites. After 8.5 years, we measured vegetation indicators commonly used to assess forest recovery, namely amount of canopy closure and number and diversity of woody recruits.Results: Two variables, grass cover and canopy closure, measured 1.5 years after site abandonment, explained 47-87% of five of the six response variables after 8.5 years; recovery was faster in sites with lower grass cover and higher canopy closure initially.Waiting an additional year to measure initial vegetation variables did not improve model fit. Time since the original forest was cleared explained 62% of change in canopy cover, whereas percentage of surrounding forest cover, length of pasture use and soil variables explained minimal additional variation. Conclusions:Our results suggest that two easily measurable vegetation variables can provide guidance to land managers and policy makers about where to invest scarce restoration resources to facilitate forest recovery. K E Y W O R D Scanopy closure, forest recovery indicators, forest restoration, grass cover, natural regeneration, secondary succession, seedling recruitment S U PP O RTI N G I N FO R M ATI O NAdditional supporting information may be found online in the Supporting Information section at the end of the article. Appendix S1. Study and site locations Appendix S2. Site characteristics Appendix S3. Vegetation sampling design Appendix S4. Correlations between initial site variables Appendix S5. Δ recruit density 8.5-1.5 as a function of canopy closure including outlier site Appendix S6. Recruit species list How to cite this article: Holl KD, Reid JL, Oviedo-Brenes F, Kulikowski AJ, Zahawi RA. Rules of thumb for predicting tropical forest recovery.

We conducted extensive mist netting and radio tracking of common frugivorous, seed-dispersing, and tropical forest-dwelling blue-crowned manakins (Lepidothrix coronata; BCMA) and white-ruffed manakins (Corapipo altera; WRMA) to study their habitat use, movements, breeding success, and seed dispersal potential in the fragmented landscape of southern Costa Rica. We obtained 1354 GPS locations from 20 BCMAs and 4040 GPS locations from 54 WRMAs we tracked. These birds were dependent on forest remnants and rarely moved through open habitats. This was more likely for WRMAs, which were slightly more tolerant of forest fragmentation. BCMAs preferred the local Las Cruces Forest Reserve and riparian corridors to smaller (\10 ha) and more isolated forest fragments. Radio tracking showed that both species used small forest fragments less than expected based on the birds' sites of capture. In general, age ratios were immature-biased and sex ratios were female-biased, especially in riparian corridors, which enabled movements across the highly deforested landscape. Average daily nest survival rate was 92.2 % for BCMA nests and 97.1 % for WRMA nests. Both species used riparian corridors 3-5 times more than expected based on land cover, utilizing these corridors for food, water, breeding, and for moving across a highly deforested landscape. Although most movements of both species were 100 m or less, some birds moved more than 600 m between observations, sometimes in only 15 min. These manakins are abundant in the forest understory and are capable of dispersing seeds more than 600 m, helping the regeneration of native vegetation. Tropical countryside riparian corridors provide critical habitat and connectivity for these common seed-dispersing forest understory birds in a fragmented landscape.