Effects of microenvironmental heterogeneity on the seed‐to‐seedling process and tree coexistence in a riparian forest

Abstract

In a temperate riparian forest, the effects of substrate types, canopy gaps and conspecific seedfall density were investigated on the seed-to-seedling process for the five dominant species (Aesculus turbinata, Fagus crenata, Acer mono, Pterocarya rhoifolia and Cercidiphyllum japonicum). Densities of seedfall and subsequent seedling recruits were measured in the stand over a period of 6 years. A model assuming that local density of seedling recruits is proportional to seedfall density in the preceding year significantly explained a spatial variation in seedling recruits for all species. Several environmental factors were then added. Substrate composition had a positive effect on P. rhoifolia and C. japonicum. P. rhoifolia was favored by gravel substrate, which also explained the adult distribution of this species in this forest. C. japonicum appeared to be facilitated by a mineral-soil substrate. However, the distributions of this substrate and adults of C. japonicum did not follow each other closely. A. mono was negatively affected by gaps, and F. crenata was negatively affected by conspecific seedfall density. In contrast, A. turbinata was not significantly affected by any of the environmental factors tested. The microenvironmental heterogeneity in this forest explained species coexistence to a limited extent in the context of seed-to-seedling processes. Performances at later stages of the life-cycle and/or catastrophic disturbances (e.g. landslides) might have a stronger influence on species coexistence in this forest.

Effects of the topographic niche differentiation on the coexistence of major and minor species in a species‐rich temperate forest

“…This result is compatible with the assumption of previous studies that the TND during early life stages takes the first priority (e.g., Shibata and Nakashizuka 1995;Masaki et al 2005), and emphasizes importance of the regeneration niche (Grubb 1977). Many previous studies found interspecies differences in response with recruitment rate to topography, but these studies failed to completely explain distribution patterns of large trees by the detected species-specific responses (e.g., Webb and Peart 2000;Nagamatsu et al 2002;Masaki et al 2007). This mismatch is attributable to two spatial processes: dispersal limitation and density-dependent mortality.…”

Habitat heterogeneity explains mosaics of evergreen and deciduous trees at local‐scales in a subtropical evergreen broad‐leaved forest

“…) and fine‐scale habitat heterogeneity has been previously shown to regulate community assembly processes (Palmer & Dixon ; McAlpine & Drake ; Masaki et al. ; Firth & Crowe ).…”

Moving from Ecological Conservation to Restoration: An Example from Central Taiwan, Asia

“…During these procedures, only a portion of trees is removed, and the overall stand abiotic environment is not greatly altered. Therefore, partial removal of trees can enhance local light availability and create physical environments similar to natural gaps that are essential for seedling survival (Augspurger, 1984;Brokaw & Busing, 2000;Masaki et al, 2007). In addition, the presence of understory vegetation may reduce seedling survival by reducing light availability or increasing competition between seedlings and understory vegetation (Leck et al, 2008).…”