Introduction. Estimating site productivity is essential for effective forest management. Site index (SI) and dominant height growth (DH) are important tools for classifying the productivity of forest stands. Objective. To fit DH and SI models for Pinus patula Schiede ex Schltdl. & Cham. and Abies religiosa (Kunth) Schltdl. & Cham. in naturally regenerated, managed forests in the state of Puebla, Mexico. Methods. A total of 179 permanent sampling plots were used, encompassing a range of stand ages, densities, and forest management conditions. A total of 422 and 153 DH-age data pairs were obtained for P. patula and A. religiosa, respectively. The algebraic difference approach (ADA) and generalized algebraic difference approach (GADA) were used to reparameterize the Bailey-Clutter, Chapman-Richards, Hossfeld IV, and Levakovic II models. The dummy variable method and generalized least squares were used for model fitting, and the models were compared using a ranking system based on five statistical indicators. Results. The parameter estimates using the ADA were significant (P < 0.05), whereas some of the GADA parameters estimates were not significant (P > 0.05). The ranking system showed that the polymorphic models based on Hossfeld IV and Chapman-Richards fitted using the ADA, had the best statistical performance for P. patula and A. religiosa, respectively. The SI trajectories generated by both models satisfactorily encompassed the observations from the permanent sampling plots. Conclusions. The models developed allow for the estimation of DH growth and the classification of stand productivity in mixed-species stands, thereby contributing to improve forest management planning.
Introduction. Ectomycorrhizal fungi of the genus Suillus have a high degree of affinity with Pinus spp.; however, associations between species of the two genera are not always compatible. To date, there are no reports describing the ectomycorrhizal association between Pinus cooperi C. E. Blanco and any ectomycorrhizal fungal species. Objective. The objective of this study was to verify and characterize the mycorrhizal association between P. cooperi and Suillus placidus (Bonord.) Singer under nursery conditions. Materials and methods. P. cooperi seedlings were inoculated at three months of age with the hymenium of S. placidus. Sixteen months after sowing, mycorrhizal roots were sampled for the molecular and morphoanatomical characterization of the ectomycorrhizal morphotypes. Results. Genetic sequencing shared 99.67-100 % identity with S. placidus sequences available in GenBank. The ectomycorrhizal system was abundant, with dichotomous morphotypes and an external mycelium containing rhizomorphs. The cellular arrangement of the fungal mantle was plectenchymatous, and the Hartig net extended to the third layer of cortical cells. Conclusion. The mycorrhizal synthesis between P. cooperi and S. placidus was confirmed. This represents the first description of a symbiotic association involving this phytobiont.
Introduction. Fire severity refers to the magnitude of ecological change caused by fire and is influenced by fire intensity and duration, as well as by vegetation density and type. Fire severity can be assessed using satellite-derived data. Objective. To analyze the major wildfires detected by the NOAA-21 VIIRS sensor in the Purépecha region of Michoacán in 2024 to determine the burned area, affected land-cover types, severity, and fire spread. Materials and methods. Using Sentinel-2 imagery of the study area, pre- and post-fire differences in the Normalized Burn Ratio (dNBR) and Normalized Difference Vegetation Index (dNDVI) were calculated and analyzed by land-cover type. Results. A total of 18 815.43 ha were burned. Agricultural burning accounted for 19 % of the burned area, while pine forest accounted for 33 %; the latter had the largest area classified as highly affected, totaling 1 088.15 ha. The analysis identified 12 burned areas, most of them located in the municipality of Chilchota. Some fires originated from agriculture burning, whereas most fires in forested areas were attributed to negligence or to the expansion of avocado production. Conclusions. The burned areas showed varying levels of fire severity, which may facilitate post-fire recovery if seed banks remain in the less severely affected patches. In pine forests, areas experiencing low to moderate fire severity showed relatively small reductions in vegetation density, suggesting that relatively rapid recovery may be expected.
