Environmental Correlates of Tree and Seedling–Sapling Distributions in a Mexican Tropical Dry Forest

Abstract

Bray and Curtis ordination was used to explore which environmental variables explained importance values and the presence-absence of tropical tree seedlings, saplings and adults in La Escondida-La Caban˜a, Sierra de Manantla´n, Jalisco, Mexico. The diameters of trees ‡2.5 cm DBH and the presence and height of seedlings and saplings were measured in nine 0.1 ha sites. Four matrices including presence-absence data and importance value indices for trees and seedlings and saplings were analyzed through Bray and Curtis ordination. The matrices were based on density, frequency, and dominance of adult trees as well as seedlings and saplings. The environmental matrix consisted of 18 variables, including elevation, slope, canopy gaps, disturbance, and soil variables. We recorded 63 tree species and 38 seedling and sapling species in the nine sites. The ordination explained 70.9% of the variation in importance value data for trees and 62.6% for seedlings and saplings. The variation explained in presence-absence data for trees was 67.1 and 77.4% for seedlings and saplings. The variance in the ordination axes of seedlings and sapling presence-absence data was poorly explained by the number of gaps in the tree, shrub, or herb layer, suggesting little light specialization by seedlings and saplings. Habitat specialization for soil nutrients appears to be important in explaining the presence-absence of seedlings and saplings. Seedling and sapling specialization along different soil microsites could promote species coexistence in this forest, while heterogeneity in light conditions may instead determine differences in growth and, thus, importance value of trees. We hypothesize that in tropical dry forest in Jalisco, Mexico, a habitat specialization for soil resources is likely more important at early stages in tree life histories than in later life history.

The effects of environmental variables and human disturbance on woody species richness and diversity in a bamboo–deciduous forest in northeastern Thailand

“…number of tree stumps) were important in determining sapling species richness and diversity. Phosphorus was the most important variable in explaining the seedling species richness and diversity, supportingVargas-Rodriguez et al (2005) who found that edaphic factors appear to be more important at the early stage of tree development than at later life stages.…”

Tree species diversity driven by environmental and anthropogenic factors in tropical dry forest fragments of central Veracruz, Mexico

“…In lowland dryland in Kenya, Mwaura and Kaburu (2009) found that woody species richness and altitudinal gradient showed a dual peak pattern with the main richness peak in low lying areas which were mainly close to a riparian environment, while the minor peak was identified in higher areas. In the TDF of Manantlán, Jalisco, Mexico, Vargas-Rodríguez et al (2005) reported that the effects of short elevation gradients may not be an overriding factor however, they found that the presence or absence of adult trees might be determined by slope and disturbance. White and Hood (2004) found that topographic and substrate attributes clearly affect the distribution and abundance of woody species in the forests of the Yucatan Peninsula.…”

“…; 10, Croton reflexifolius; 11, Acalypha adenostachya; 12, Acalypha alopecuroides; 13, Luehea candida; 14, Randia monantha; 15, Astronium graveolens; 16, Citharexylum berlandieri Gallardo-Cruz et al 2005;Gillespie et al 2000). Mexican TDF grows predominantly on moderate to steep slopes, with shallow soils and rocky or limestone outcrops (Trejo and Dirzo 2002;Gallardo-Cruz et al 2005;Vargas-Rodríguez et al 2005;Durán et al 2006), but exceptionally TDF can grow on different substrates such as on volcanic rock formations (Castillo-Campos et al 2007).…”

“…The mosaic of biotic and environmental conditions found within topographically complex TDF likely play a fundamental role in the maintenance of the elevated species diversity found in these ecosystems (Segura et al 2003). Other authors have reported that different microhabitat conditions influence species differentiation among canopy and subcanopy trees (Vargas-Rodríguez et al 2005).…”

Historia natural y cosecha de corteza de quina amarilla Hintonia latiflora (Rubiaceae)

“…La especie crece sobre material parental ígneo o granítico, sedimentario, en suelos arcillosos y limosos, de color negro, rojo o amarillo-rojizo; en altitudes que varían entre 10 y 2,200 m snm (López et al, 2011). En Chamela, Jalisco, la quina vive sobre suelos con textura arenosa, principalmente en los de alto intercambio de iones y de MgO (Vargas-Rodríguez et al, 2005). En cuanto a la interacción de H. latiflora con la biofí-sica del suelo, se ha mencionado que la simbiosis micorrizó-gena aporta minerales adquiridos por el hongo para favorecer características del desarrollo, como velocidad de crecimiento, altura y tasa de producción de hojas y ramas en el dosel Figura 1.…”