Effects of Distance and Neighbor Size on Abies hickelii: The Asymmetric Competition Is Aggravated in an Endangered Species

Abstract

One of the hypotheses in the field of forest ecology suggests that competition among individual plants is asymmetric or unidirectional. This notion holds particular significance for endangered species, necessitating a comprehensive assessment of the impact of their closest competitors to understand their spatial distribution and local-scale interactions. The mean response of Abies hickelii’s diameter at breast height and total height was determined for each unit that increased the distance from its neighbor and each unit that changed the size of its neighbor. The results obtained through the analysis of covariance suggest that, for each meter that the distance from the neighbor increases, there is a mean gain of 1.13 cm in the diameter of the individuals studied. The height results showed higher sensitivity to changes in the neighbor distance than the diameter. It was observed that the population is exposed to asymmetric competition, suggesting that larger individuals take available resources disproportionately, thereby inhibiting the growth of smaller individuals. The intraspecific competition surpassed the interspecific competition. A suggestion was made to use selective thinning during the early-growth stages of the species. The habitat of the species studied is under strong pressure from land use change due to clandestine logging, the opening of roads, and other anthropogenic effects. Thus, these results represent an important step in the implementation of action strategies to preserve the species in the wild.