Is there environmental differentiation in the Quercus-dominated forests of west-central Mexico?

Abstract

Detailed information on 38 species and 26 environmental variables was recorded from a network of 86 permanent plots across a geographical range of 10 km, in order to determine the patterns of floristic composition in Quercus-dominated forests; to elucidate environmental differentiation in such forests; and to determine whether species are partitioning their environment. To examine likely patterns of floristic composition, a data matrix expressed as relative volume ? relative density was used to run non-metric multidimensional scaling. Canonical correspondence analysis extracted the environmental variation that best correlates with the observed patterns of floristic composition. Our results indicate that congeneric Quercus individuals represent the largest proportion of the species pool in the study plots. They coexist with other species having similar ecological requirements in at least three distinct floristic groups. Examination of the two largest groups and their species compositions reveals that one floristic gradient runs across the most xeric zone of the study area, and the second major floristic gradient runs across a mesic zone. The most important environmental variable explaining the observed patterns of floristic composition is altitude, although partial canonical correspondence analysis suggests that micro-habitat heterogeneity (catena position and canopy maturity) was most significant.

Environmental and soil variables affecting the structure and floristic woody composition of oak forests of northeastern Mexico

“…at the highest elevations, confirming the specialist behavior of Quercus species with regard to altitude (Olvera-Vargas et al, 2010). Altitude gradient was also an important factor determining patterns of floristic composition in oak forests in west-central Mexico (Olvera-Vargas et al, 2010) and in the northern Oaxaca range in Mexico (Meave et al, 2006 which determine soil fertility (Mengel and Kirkby, 2001). In the forests studied, chemical properties such as organic matter and NPK nutrients are similar through the oak forests; in this way, there are no significant differences, and this is because the soils of both forests are derived from limestone rocks.…”

“…However, perhaps more important is the low rainfall, because this mountain is located near the Chihuahuan Desert Region (Henrickson and Johnston, 1986), which is characterized by low to moderate rainfall. According to Rzedowski (2006), most oak forests in Mexico grow in areas with rainfall greater than 600 mm, reaching 1500 mm or more in neotropical montane oak forests, which have high basal areas and densities, including the oak forest highlands of Chiapas (González-Espinosa et al, 2006) and northern Oaxaca (Meave et al, 2006), and the humid montane oak forests of west Mexico (Olvera-Vargas et al, 2010).…”

Patterns of distribution of nine Quercus species along an environmental gradient in a fragmented landscape in central Mexico

“…The first one indicates that coexistence could be promoted by being temporally separated in their growth stages (i.e. acorn maturity and seedling establishment at different moments of the year) (Cavender-Bares and Pahlich 2009;Olvera-Vargas et al 2010;Pérez-López et al 2013) or by exploiting different areas of the soil water-table depth (López-Barrera et al 2006;Pérez-López et al 2013). Another hypothesis is that one of the species could get advantage from the presence of the other by positive synergic effects, which could promote the establishment and survival of both species in the same site (Chávez-Vergara and García-Oliva 2013).…”

“…Furthermore, closely-related oak species tend to diverge in their habitat preferences to avoid competition, as well as in response to environmental factors (Torrez-Meza et al 2009;Olvera-Vargas et al 2010;Pérez-Ramos et al 2012;de la Riva et al 2014). Particularly, nutrient availability and fire regime, topography, soil and altitude frequency have influenced oak distribution (Abrams, 1990;2003;Cavender-Bares et al 2004;Meave et al 2006;Olvera-Vargas et al 2010;Rodríguez-Trejo and Myers 2010;de la Riva et al 2014). However, it is still unknown if these patterns of oak distribution hold at regional scales.…”

“…At a continental scale, white oaks (section Quercus) occur in drier and warmer environments than red oaks (section Lobatae), which are distributed in more humid and colder sites (Zavala-Chávez., 1998: Abrams, 2003Valencia-A., 2004;Mills, 2009;Torres-Miranda, 2009; Torrez-Meza et al 2009;Rodríguez-Trejo and Myers 2010). Furthermore, closely-related oak species tend to diverge in their habitat preferences to avoid competition, as well as in response to environmental factors (Torrez-Meza et al 2009;Olvera-Vargas et al 2010;Pérez-Ramos et al 2012;de la Riva et al 2014). Particularly, nutrient availability and fire regime, topography, soil and altitude frequency have influenced oak distribution (Abrams, 1990;2003;Cavender-Bares et al 2004;Meave et al 2006;Olvera-Vargas et al 2010;Rodríguez-Trejo and Myers 2010;de la Riva et al 2014).…”