Are cloud forest tree structure and environment related in the Venezuelan Andes?

Abstract

Cloud forest vegetation structure and composition were studied in the Venezuelan Andes at three sites in Mérida State. Although the sites are within 10 to 30 km of each other, climatic, geologic and topographic differences are remarkable. The main purpose of the study was to determine the relationship of specific environmental variables to forest vegetation characteristics, including basal area, tree height, density and diversity, and leaf area index (LAI). At 51 plots, all trees' diameter at breast height >10 cm were recorded and identified. Although the environment at the three sites is distinctive, the tree species composition of the most abundant species was very similar. None of the measured environment variables were significantly correlated with the measured vegetation structure variables, except LAI, which was correlated with slope orientation; LAI showed higher values at southfacing plots. Tree height was relatively uniform, while basal area was highly variable and reached very high values. Stem densities were in the range reported elsewhere in cloud forests. Multivariate analysis using structure or composition data shows segregation of the plots by site. Principal component analyses by site indicate a minor impact of environmental factors on forest variables. At each site, a particular group of species are correlated with the ordination axes. We conclude that species pools and forest dynamics add to the complexity of the structure of the studied cloud forests.

Gradient (elevation) vs. disturbance (agriculture) effects on primary cloud forest in Ecuador: floristics and physical structure

“…In Puerto Rican "dwarf" cloud forest, there were many small stems (3671/ha) but the basal area was comparable to Monteverde in Costa Rica (49.1 m 2 /ha: Weaver et al 1986). In cloud forests closer to Ecuador (Venezuela) sampled to a dsh of at least 10 cm, the stem density (365-850/ha) and species richness (9-14/ha) was also comparable (Schwarzkopf et al 2011). Previous studies of the sugarcane and banana plots have compared floristics and physical structure like in this study (Myster 2007a); for example, relationships between richness and productivity (Myster 2009) and dominance-diversity curves (Myster 2010a(Myster , 2010b.…”

Estructura De Bosques Secundarios Y Rastrojos Montano Bajos Del Norte De Antioquia, Colombia

“…Por tanto, el espectro de aplicación del concepto de estructura se amplía enormemente, incluso a la estructura de copas, estructura espacial de una especie, riqueza florística y diversidad (Rollet, 1980). Por ejemplo, algunos autores estudiaron elementos estructurales diferentes como la altura de los árboles (Ariza et al, 2009), el área basal (Álvarez-Yépiz et al, 2008), las copas de los árboles (Hiroaki & McDowell, 2002;Aiba et al, 2004) y el índice de área foliar (Schwarzkopf et al, 2011). Sin embargo, la variable que más se usa para describir la estructura es el diámetro a la altura del pecho (Hering, 2003;Newton, 2007).…”

Distribution of juveniles of tree species along a canopy closure gradient in a tropical cloud forest of the Venezuelan Andes

“…Like other tropical forests, the environment in cloud forest understory is very heterogeneous at spatial and temporal scales. The frequent cloudiness together with high topographic variation accentuates this heterogeneity, which imposes energetic limitations and affects other factors such as evapotranspiration, temperature and humidity (Hogan & Machado 2002, Schwarzkopf et al 2011.…”