Tree and shrub recruitment under environmental disturbances in temperate forests in the south of Mexico

Abstract

Background: Recruitment after disturbance events depends on many factors including the environmental conditions of the affected area and the vegetation that could potentially grow in such affected areas. To understand the regeneration characteristics that occurs in temperate forests, we evaluated differences in the number of seedlings from trees and shrubs along an altitudinal gradient in Sierra Norte of Oaxaca, Mexico in different biological, climatic, edaphic, light, topographic, and disturbance regimes. Here, we aimed to test the hypothesis that the environmental disturbances influence on recruitment (positive or adverse influence). We sampled the vegetation to obtain recruitment and adult data, and species composition.

Results: We identified three disturbance regimes: areas affected by forest harvesting, areas exposed to pest management, and undisturbed areas. We identified 29 species of trees and shrubs (9 species of the genus Pinus, 1 species of the genus Abies, 10 species of the genus Quercus, and 9 of other species of broadleaf). We found that both environmental conditions and disturbances influence the recruitment of vegetation in the study area. In particular, disturbances had a positive influence on the regeneration of oak and other broadleaf species by increasing the number of seedlings, and a negative influence on the regeneration of conifers by decreasing the recruitment. Because the recruitment of conifers is more likely in undisturbed areas (sites over 3050 m).

Conclusions: Environmental factors and anthropogenic disturbances can alter the recruitment of forests. Consequently, knowing which factors are key for the recruitment of vegetation is fundamental for decision-making processes. This is particularly relevant in areas as the one in this study because it provides knowledge to local people on vegetation recovery for a proper management of their biological resources.

Keywords: Conifer; Disturbances; Forest; Forest harvesting; Forest pest management; Oak; Regeneration.

Fig. 1

Study area located in the Sierra Norte in the state of Oaxaca, Mexico

Fig. 2

Number of individual per hectare of adults (gray bars) and by recruitment (black bars) for a conifers, b oaks, and c other broadleaf species along to altitudinal gradient studied

Fig. 3

Averages and standard errors of number of the individual by recruitment (black circles) and adults (white circles) for a conifers, b oaks, and c other broadleaf species according to disturbance regimes (forest harvesting, forest pest management, and undisturbed areas)

Fig. 4

Haberman’s adjusted residues values of the number of the individuals by recruitment for each disturbance regime (H, forest harvesting; P, forest pest management; U, undisturbed areas). Values higher than + 1.96 indicate a greater recruitment according to the regime of disturbance, and values lower than − 1.96 indicate a lower recruitment due to disturbances

Fig. 5

Analysis of Canonical Correspondence (CCA) between environmental and biological variables (CR, abundance of individuals by recruitment of conifers; CA, abundance of adult individuals of conifers; QR, abundance of individuals by recruitment of oaks; QA, abundance of adult individuals of oaks; BR, abundance of individuals by recruitment of other broadleaf species; BA, abundance of adult individuals of other broadleaf species; S, site; H, Forest harvesting; P, Forest pest management; U, undisturbed areas)