Tropical forest restoration enriches vascular epiphyte recovery

Abstract

Questions: Vascular epiphytes constitute a large proportion of tropical forest plant biodiversity, but are among the slowest plants to recolonize secondary forests. We asked whether tree planting for ecological restoration accelerates epiphyte community recovery. Does the spatial configuration of tree planting matter? What landscape contexts are most suitable for epiphyte restoration?Location: Restored pastures in premontane Coto Brus County, Puntarenas, Costa Rica. Methods:We surveyed vascular epiphyte species growing on the lower trunks of 1083 trees in 13 experimental restoration sites. Each site contained three 0.25-ha treatment plots: natural regeneration, trees planted in patches or 'islands' and tree plantations. Sites spanned elevational (1100-1430 m) and deforestation (4-94% forest cover within a 100-m radius around each site) gradients.Results: Vascular epiphytes were twice as diverse in planted restoration plots (islands and plantations) as in natural regeneration; we observed this at the scale of individual host trees and within 0.25-ha treatment plots. Contributing factors included that trees in planted restoration plots were larger, older, more abundant and composed of different species than trees in naturally regenerating plots. Epiphyte species richness increased with surrounding forest cover within 100-150 m of restoration plots. Epiphyte communities were also twice as diverse at higher (1330-1430 m) vs lower (1100-1290 m) elevation sites. Epiphyte groups responded differently to restoration treatments and landscape factors; ferns were responsible for higher species richness in planted restoration plots, whereas angiosperms drove elevation and forest cover effects.Conclusions: Tree planting for ecological restoration enriched epiphyte communities compared to natural regeneration, likely because planted forests contained more, bigger and older trees. Tree island plantings were equally effective compared to larger and more expensive plantations. Restoration sites nearer to existing forests had richer epiphyte recolonization, likely because nearby forests provisioned restoration sites with angiosperm seeds. Collectively, results suggest that restoration practitioners can enrich epiphyte community development by planting trees in areas with higher surrounding forest cover, particularly at higher elevations.

Exotic weeds and fluctuating microclimate can constrain native plant regeneration in urban forest restoration

“…, Reid et al. ). Additionally, as epiphytes accumulate, their own biomass creates further microclimatic buffering, facilitating greater epiphytic colonization (Reid et al.…”

“…Additionally, as epiphytes accumulate, their own biomass creates further microclimatic buffering, facilitating greater epiphytic colonization (Reid et al. ). Other studies have found that restored forests often support greater diversity and density of epiphytes compared to unrestored or spontaneously regenerated forests (Kanowski et al.…”

“…, Reid et al. ). However, our understanding of the dynamics that occur in restored forests over decadal time scales is limited by a lack of long‐term monitoring and the fact that most forest restoration projects have only started within the past few decades (Ruiz‐Jaen and Aide , Oldfield et al.…”

Applied Vegetation Science enters its 20th year

“…Reid et al. () studied vascular epiphytes at experimental forest restoration sites on former pastures in Costa Rica. They found that epiphyte diversity is restored better when restoration involves tree planting, as opposed to natural regeneration.…”

Tank bromeliad transplants as an enrichment strategy in southern Costa Rica

“…In regenerating tropical forests, epiphyte colonization and seedling survival are limited by a diversity of factors, such as microclimatic conditions (Benzing ; Castro‐Hernández et al ; Toledo‐Aceves & Wolf ; Toledo‐Aceves et al ), low probabilities of seed arrival to host trees, low rates of germination (Mondragon & Calvo‐Irabien ), structural characteristics of host trees, and the lack of a dense moss cover (Krömer & Gradstein ). Among these factors, dispersal limitation is an important barrier to epiphyte colonization and recruitment, especially in fragmented landscapes (Mondragon & Calvo‐Irabien ; Cascante‐Marín et al ; Reid et al ). Therefore, manually transplanting epiphytes could be a good strategy for vascular epiphyte reintroduction (Toledo‐Aceves & Wolf ).…”