Community assembly during secondary forest succession in a Chinese subtropical forest

Abstract

(2011). Community assembly during secondary forest succession in a Chinese subtropical forest. Ecological Monographs, 81(1): 25-41. Community assembly during secondary forest succession in a Chinese subtropical forest Abstract Subtropical broad-leaved forests in southeastern China support a high diversity of woody plants. Using a comparative study design with 30330 m plots (n=27) from five successional stages (<20, <40, <60, <80, and ≤80 yr), we investigated how the gradient in species composition reflects underlying processes of community assembly. In particular, we tested whether species richness of adult trees and shrubs decreased or increased and assessed to which degree this pattern was caused by negative density dependence or continuous immigration over time. Furthermore, we tested whether rare species were increasingly enriched and the species composition of adult trees and shrubs became more similar to species composition of seedlings during the course of succession. We counted the individuals of all adult species and shrubs >1 m in height in each plot and counted all woody recruits (bank of all seedlings ≤1 m in height) in each central 10310 m quadrant of each plot. In addition, we measured a number of environmental variables (elevation, slope, aspect, soil moisture, pH, C, N, and C/N ratio) and biotic structural variables (height and cover of layers). Adult species richness varied from 25 to 69 species per plot, and in total 148 woody species from 46 families were recorded. There was a clear successional gradient in species composition as revealed by nonmetric multidimensional scaling (NMDS), but only a poor differentiation of different successional stages with respect to particular species. Adult richness per 100 individuals (rarefaction method) increased with successional stage. None of the measured abiotic variables were significantly correlated with adult species richness. We found no evidence that rare species were responsible for the increasing adult species richness, as richness of rare species among both adults and recruits was independent of the successional stage. Furthermore, the similarity between established adults and recruits did not increase with successional stage. There was a constant number of recruit species and also of exclusive recruit species, i.e., those that had not been present as adult individuals, across all successional stages, suggesting a continuous random immigration over time. variables were significantly correlated with adult species richness. We found no evidence that 41 rare species were responsible for the increasing adult species richness, as richness of rare 42 species amongst both adults and recruits was independent of the successional stage.

Tree phylogenetic diversity promotes host–parasitoid interactions

“…Plot selection was based on successional age (less than 20 to more than 80 years since the last land use) and tree species richness (25-69 species), which were not correlated. For more details and botanical information, refer to Bruelheide et al [29] and for a map of the study site to Staab et al [30].…”

“…Canopy layer cover (%) was the proportion covered by the highest tree layer and shrub layer cover (%), the proportion covered by low woody vegetation. Successional age (years) was determined from stem core drillings (details in [29]). Herb layer cover (%) was the proportion covered by vegetation less than 1 m in the central 100 m 2 of each plot.…”

“…Herb layer cover (%) was the proportion covered by vegetation less than 1 m in the central 100 m 2 of each plot. Herb species richness was not analysed as most plants smaller than 1 m were recruits of woody species growing on the same plot [29].…”

“…Canopy cover influences a forests' climate [54] and is in the GNNR highly correlated with successional age. Also, older plots had fewer deciduous trees [29] and a higher leaf area index, resulting in less insolation of the understory and wetter and cooler conditions [55]. Solitary nest-provisioning Hymenoptera, however, need light and warmth for effective foraging [28] and brood development [56].…”

“…Our study was conducted on the 27 well-studied plots of the BEF-China Project (www.bef-china.de, [29]) that allowed the inclusion of a broad set of abiotic (e.g. elevation) and biotic (e.g.…”