Spatial structure of the abiotic environment and its association with sapling community structure and dynamics in a cloud forest

Abstract

Analyzing the relationship between the spatial structures of environmental variables and of the associated seedling and sapling communities is crucial to understanding the regeneration processes in forest communities. The degree of spatial structuring (i.e., spatial autocorrelation) of environmental and sapling community variables in the cloud forest of Teipan, S Mexico, were analyzed at a 1-ha scale using geostatistical analysis; after fitting semivariogram models for each set of variables, the association between the two sets was examined through cross-variograms. Kriging maps of the sapling community variables (density, cover, species richness, and mortality and recruitment rates) were obtained through conditional simulation method. Canopy openness, total solar radiation, litter depth, soil temperature and soil moisture were spatially structured, as were sapling density, species richness and sapling mortality rate. Mean range in semivariograms for environmental and sapling community variables were 13.14 ± 3.67 and 12.68 ± 5.71 m (±SE), respectively. The spatial structure of litter depth was negatively associated with the spatial structures of sapling density, species richness, and sapling community cover; in turn, the spatial structure of soil moisture was positively associated with the spatial structure of recruitment rate. These associations of the spatial structures of abiotic and sapling community variables suggest that the regeneration processes in this cloud forest is driven by the existence of different microsites, largely characterized by litter depth variations, across which saplings of tree species encounter a range of opportunities for successful establishment and survival.

Recruitment patterns and potential mechanisms of community assembly in an Andean cloud forest

“…It is well known that light is a crucial factor in sapling establishment, and its importance has been observed in previous studies conducted in tropical wet forests (Montgomery & Chazdon ), as well as in cloud forests (Mejía‐Domínguez et al. ). However, our results revealed that the level of light required for sapling establishment in the studied cloud forest differs from those reported for tropical rain forests, as also distances of density dependence differed.…”

“…Consequently, the spatial distribution of adult trees influences the spatial distribution of saplings in cloud forests, as elsewhere (Mejía‐Domínguez et al. ).…”

“…A second process that also partially explains the spatial pattern of woody species in cloud forests is niche association, or habitat differentiation (Mejía‐Domínguez et al. ; Ledo et al. ).…”

Species presence frequency and diversity in different patch types along an altitudinal gradient:Larix chinensisBeissn in Qinling Mountains (China)

“…These heterogeneous environmental factors can play an important role in the growth and regeneration of plants in different patch types with different ecological characteristics. Heterogeneous patches show selectivity for species of a diversity sizes and functions ( Mejía-Domínguez, Meave & Díaz-Ávalos, 2012 ). Our present results support and enrich those of previous studies.…”

“…For various gap-forming processes, canopy dynamics are diverse and patches change with time and space. Diverse patches present heterogeneous environmental factors providing the necessary ecological basis for the coexistence of species (or functional groups) with different ecological demands in their different life history stages ( Mejía-Domínguez, Meave & Díaz-Ávalos, 2012 ). Mosaic patches can further be subdivided: gap and non-gap ( Brokaw, 1982 ); gap, non-gap and expanding gap; gap, closed canopy and gap adjacent areas ( Manabe & Yamamoto, 1997 ); and closed canopy type (CC-Type), gradually closing type (GC-Type), expanding gap (GG-Type) and newly created gap type (NG-Type) ( Manabe et al, 2009 ).…”