The wave effect and the shyness phenomenon in Alnus acuminata (Kunth) are crown parameters rarely studied, but important in the quality of the wood of standing trees, therefore, a morphometric modeling of the crowns of Alnus acuminata in homogeneous forests in the Sierra Norte de Puebla was carried out. In 20 rectangular sites of 1,000 m², the following were evaluated: total height (TA), normal diameter (ND), crown diameter (CD) and crown cover (CC). The Kruskal Wallis test was applied to data that did not meet the assumption of normality; for those that did, analysis of variance (ANOVA) was used, with Tukey mean comparison tests (α ≤ 0.05). The forest value index was 14.99, so its two-dimensional structure is normal based on DN, AT and CC. Its average slenderness index was 93.52, which makes the tree not very stable to mechanical damage. The life-space index was 38.92, which is high indicating that trees with low intraspecific competition developed better. At the canopy level, a pattern following an upward, oscillatory and constant wave effect was observed in groups of 10 trees. The shyness phenomenon showed an average crack opening of 27.39 cm between canopies, so this phenomenon is well defined for the species. It is concluded that in the crowns of Alnus acuminata, the wave effect is observed as a consequence of inequality in the acquisition of resources, and one way to minimize this inequality is through the phenomenon of botanical shyness.

Taking the 13 years pure artificial forest Phoebe chekiangensis and heterogeneous mixed forests in Tiantong mountain, Zhejiang Province as the research object, the characteristics of stand development, tree competition differentiation, tree height/breast diameter ratio and dominant wood growth were compared and analyzed from the perspective of ecology. The results show that compared with pure forests, the growth advantages of heterogeneous mixed-age forests were significant. Average breast diameter growth of stand increased 1.8%; the growth of single plant wood accumulation increased 7.4%. The relationship between tree height and diameter showed that the high growth of Phoebe chekiangensis individuals in the heterogeneous mixed forest was significantly promoted, and the high growth of the tree was 8.4% higher than that of pure forest. 1–5 grade wood scale sizes Phoebe chekiangensis in heterogeneous mixed forests and pure forests are ranked grade 3 (43.7%) > grade 2 (26.5%) > grade 4 (15.7%) > grade 1 (12.9%) > grade 5 (1.2%); grade 3 (34.7%) > level 2 (25.6%) > level 4 (20.0%) > level 1 (18.2%) > level 5 (1.2%); the straight-diameter structure shows a normal distribution, and the degree of differentiation of pure forests is greater than that of heterogeneous forests. The dominant trees of Phoebe chekiangensis pure forest and heterogeneous forest accounted for 18.2% and 12.9% of the total number of plants respectively, providing a reserve of 51.1% and 35.4% respectively, reflecting the contribution of dominant trees caused by the self-thinning effect.

Important modifications are occurring in temperate forests due to climate change; in polar latitudes their distribution area is increasing, while in tropical latitudes it is decreasing due to temperature increase and droughts. One of the biotic regulators of temperate forests are the debarking insects that cause the mortality of certain trees. These insects have increased in number, favored by climate change, and the consequences on forests have not been long in coming. In recent times in the northern hemisphere, the massive mortality of conifers due to the negative synergy between climate change and debarking insects has been evident. In Mexico, we have also experienced infestations by bark stripping insects never seen before; therefore, we are trying to understand the interactions between climate change, forest health and bark stripping insects, to detect the areas with greater susceptibility to attack by these insects and propose management measures to reduce the effects.

No less than 60% of timber production in Peru’s natural forests is the result of informal or illegal extractive activities that, by definition, are not sustainable. This article aims to demonstrate that even legitimate timber, such as timber harvested in more than 6 million hectares of forest concessions, does not meet the basic requirements of sustainable forest management. Forestry legislation itself, which does not emphasize forest management, institutional weaknesses and the socioeconomic environment are the main causes. In addition, the cutting cycles and the authorized minimum diameters, among other practices, do not allow the renewal of the resource and increase its degradation.

The Nevado de Toluca Flora and Fauna Protection Area presents a constant fragmentation of its forests. The objective of the research was to identify the processes of forest deterioration and the role of local stakeholders in its conservation. Geographic information systems were used as a basis for the generation of thematic maps, in addition to the application of a flow diagram that defines the problems of the forest and another that describes and analyzes them for the search of solutions. The results show that the main factors affecting deterioration are forest fires, immoderate logging, pests and diseases. Finally, strategies and scenarios for forest management are proposed based on the articulation of local stakeholders.