Figure 1.
Location of study area.
Figure 2.
Relative frequency of trees species in the Sierra Madre Occidental.
The names of the 16 most frequent species found in the study area are shown.
Figure 3.
Design of a single plot included in the National Forest and Soil Inventory (modified from CONAFOR, 2004).
The plot is composed of four 400 m2 subplots distributed as an inverse ‘Y’. Abbreviations: Az = Azimuth, m = meters, N = North; SE = Southeast; SW = Southwest
Table 1.
Basic statistics of the geographical, climatic and species diversity variables studied.
Table 2.
Matrix of Spearman correlation (rS) between climate variables.
Table 3.
Matrix of Spearman correlation (rS) calculated from the climate and diversity variables.
Figure 4.
Series of curves of the quantile regression for tree species richness (v0), the effective tree species number (v2) and the amount of prevalent tree species (v∞) for quantile levels of (τ) 0.1, 0.5, and 0.9.
The climatic variables are as follows: mean annual temperature (MAT), mean temperature in the warmest month (MTWM), maximum temperature in the warmest month (MMAX), annual aridity index (AAI), and finally, the number of individuals per plot (NIP).
Table 4.
The parameters and probability of error (p) of polynomial nonlinear quantile regression models of diversity indices with climatic variables at the 0.9, 0.5 and 0.1 quantile levels (τ).
Table 5.
Points of local minimum (Min) and maximum values (Max) of the tree species richness (v0), the effective tree species number (v2) and the number of prevalent tree species (v∞) with (τ) 0.5, and 0.9 as the quantile levels.
Table 6.
The parameters a, b and c, probability of error (p) and the error of linear multivariate models of diversity indices (error) with climatic variables MMAX and MAP at the 0.1, 0.5 and 0.9 quantile levels (τ).
Figure 5.
Curves of quantile regression with combinations and relationship between MMAX and AAI, Sierra Madre Occidental, Durango.
Those shown are number of individuals per plot (NIP) with mean annual temperature (MAT, r2 = 0.52); annual aridity index (AAI, r2 = 0.47) and maximum temperature in the warmest month (MMAX, r2 = 0.46). The correlation was calculated with the quadratic function by quantile regression (τ = 0.5). Relationship between MMAX and AAI on the Sierra Madre Occidental, Durango, A = part facing inland and B = part facing Pacific Ocean.
Figure 6.
Linear multivariate model of tree species diversity with temperature and precipitation.
Included tree species richness (v0), effective tree species number (v2) and the number of prevalent tree species (v∞) with mean annual precipitation (MAP) and maximum temperature in the warmest month (MMAX) for quantile levels of (τ) 0.1, 0.5, and 0.9.