Regeneration patterns in Mexican pine-oak forests

Forest Ecosystems

Table 1 Estimated coefficients (and corresponding standard errors, S.E.) of generalized linear mixed-effects models of the presence of saplings and small trees (binomial variable: yes, no) as a function of family (Fagaceae or Pinaceae), overstory composition (Overstory; oak, mixed or pine), total plot basal area (BA), climate variables (mean annual temperature and annual precipitation), occurrence of several disturbance types (wildfires, grazing, pests, wood extractions), land tenure (private, public or social), and the interactions between family and all the other variables

Variable	Saplings	Small trees
Variable	(Coef. ± S.E.)	(Coef. ± S.E.)
(Intercept)	−2.07 ± 0.90*	−0.03 ± 0.69
Family Pinaceae	− 0.08 ± 0.99	2.00 ± 0.89*
Overstory mxed	−0.30 ± 0.10**	−0.18 ± 0.08*
Overstory pine	−1.72 ± 0.16***	−2.30 ± 0.19***
sqrt (Total BA)	0.04 ± 0.04	0.04 ± 0.03
log (Mean temperature)	0.63 ± 0.24**	0.11 ± 0.19
log (Precipitation)	0.27 ± 0.14*	0.02 ± 0.11
Wildfires	0.54 ± 0.10***	0.01 ± 0.07
Grazing	−0.22 ± 0.09**	−0.23 ± 0.06***
Pests	0.09 ± 0.12	0.04 ± 0.09
Wood extractions	0.19 ± 0.11	0.05 ± 0.08
Land tenure Public	−0.65 ± 0.45	−0.15 ± 0.41
Land tenure Social	0.06 ± 0.09	−0.05 ± 0.07
Family Pinaceae: Overstory mixed	3.25 ± 0.18***	3.36 ± 0.22***
Family Pinaceae: Overstory pine	5.22 ± 0.26***	5.64 ± 0.31***
Family Pinaceae: sqrt (Total BA)	0.04 ± 0.06	0.07 ± 0.05
Family Pinaceae: log (Mean temperature)	−1.97 ± 0.29***	−2.63 ± 0.26***
Family Pinaceae: log (Precipitation)	0.08 ± 0.17	0.09 ± 0.15
Family Pinaceae: Wildfires	−0.57 ± 0.12***	−0.39 ± 0.10***
Family Pinaceae: Grazing	0.24 ± 0.11*	0.44 ± 0.10***
Family Pinaceae: Pests	0.04 ± 0.16	0.22 ± 0.13
Family Pinaceae: Wood extractions	0.22 ± 0.14	0.20 ± 0.12
Family Pinaceae: Land tenure Public	0.98 ± 0.65	0.42 ± 0.65
Family Pinaceae: Land tenure Social	0.09 ± 0.12	0.24 ± 0.11*

Coefficient values are given relative to the reference level for each factor-type variable (Family = ‘Fagaceae’, Overstory = ‘Oak’, Land tenure = ‘Private’, and no/low disturbance level for all disturbance types), which implies that the estimate for the reference level of each factor is included in the intercept, and the coefficients for the additional (non-reference) factor levels indicate how they deviate from the overall intercept. The same applies to interactions with family: the coefficients corresponding to each of the other explanatory variables (without interaction) correspond to their estimated effect for Fagaceae (the reference level for family), whereas the bottom 11 rows show how this effect is modified for Pinaceae species. Conglomerate nested in state were included as random factors. Some variables were log- or square-root (sqrt) transformed to ensure normality, as indicated below. Significance codes: * 0.05 < P < 0.01; ** 0.01 < P < 0.001; *** P < 0.001