Successional dynamics of woody seedling communities in wet tropical secondary forests

Abstract

Summary1 Chronosequence studies have found that shrubs and lianas are generally more abundant in early stages of tropical forest succession, whereas canopy trees and palms become more abundant and species-rich in older stages and mature forests. 2 We analysed changes in woody seedling communities over 5 years in four secondgrowth forests (initially 13-26 years after pasture abandonment) in Costa Rica. We recorded community-level changes in woody seedling density, species density, species richness and composition in six woody life-forms: canopy trees, subcanopy trees, canopy palms, understorey palms, shrubs and lianas. We evaluated these changes in relation to annualized recruitment and mortality rates for each life-form. 3 Seedling density declined in all four sites over the 5 years, whereas Shannon diversity and the proportion of rare species increased. Species richness and evenness increased in all but the oldest site. 4 Canopy palm, understorey palm and canopy tree seedlings increased in species richness and relative abundance, whereas shrub and liana relative abundance declined. Canopy trees accounted for 34-42% of all new recruits. Detrended correspondence analysis showed that species composition was initially highly distinct within each forest site and remained distinct over the 5-year period. 5 Shifts in life-form were correlated with declining light availability during succession. Across sites, median light availability at the end of the study period in 2003 was positively correlated with recruitment rates of understorey palms, shrubs and lianas, and was negatively correlated with mortality rates of canopy trees and palms. 6 Observed changes among seedling communities mirrored those described in chronosequence studies on plants in larger size classes, lending support to the assumptions of chronosequence studies in Neotropical forests. 7 The results demonstrate the importance of seedling recruitment and mortality in determining the course of succession. Convergence occurs in some community properties, such as relative abundance within life-forms, but not in others, such as species composition. Finally, the results illustrate the value of studying plant community dynamics at the level of woody life-forms, especially in hyperdiverse systems such as tropical forests.

Species diversity and successional dynamics in the secondary forest of Obafemi Awolowo University Biological Gardens Ile-Ife, Nigeria

“…This could be because the younger plot was still in the preliminary phase of colonisation whereby newer species are still arriving, whereas the older plots have attained some level of stability and tending towards another successional phase. This supports the assertion of Capers et al (2005) who reported that evenness of species appear to increase for at least 30 years after pasture abandonment in wet tropical forests in Costa Rica. They attributed this to an increase in tree species as a proportion of all species with successional age and also because the proportion of rare tree species was higher in the oldest site than in the youngest.…”

Interactions between repeated fire, nutrients, and insect herbivores affect the recovery of diversity in the southern Amazon

“…Areas undergoing secondary succession in general become more diverse with time, but species composition is slow to recover or converge between sites, even those that are close together (Capers et al 2005). In our study, diversity and the number of current year recruits decreased over the dry season; for diversity, this pattern was more pronounced in burned plots.…”

Landscape Attributes Drive Complex Spatial Microclimate Configuration of Brazilian Atlantic Forest Fragments

“…Fragments largely or entirely consisting of edge-affected habitats cannot retain a full complement of life-history traits in plant communities, and consequently the plant-animal interaction webs constitute distorted communities. Therefore, the conservation value of small forest fragments will largely depend on the mitigation of edge effects (and their cascades of species extirpation) via a combination of landscape-scale landuse regulations, e.g., keeping landscape structural connectivity via protection of gallery forest [8], plus fragment-scale assisted interventions such the control of liana populations [46], species reintroduction and enrichment [47][48], assisted seedling recruitment [49], and fragment buffering via second-growth vegetation [48,50]. Such interventions may be rendered ineffective by a priori assumptions that aging fragments immersed in open-habitat matrices are concentric-shaped in terms of microclimatic/biological configuration.…”