Forest disturbances increase the body mass of two contrasting ungulates.
Abstract
As climate change intensifies and demand for timber rises, forest disturbances are increasing. Disturbances in forests cause an abrupt loss in canopy cover and increase resource availability on the ground, which can have manifold effects on the habitat quality of forest-dwelling species. One pathway through which disturbances influence habitat quality is by creating edges within forests. Disturbance-created edges differ from edges to other land cover types in that they are transient, that is, they persist only for a limited period of time until canopy closes again. While the effects of permanent edges are well-studied in ecology, the role of transient edges remains largely unclear. Here, we investigated whether edges caused by forest disturbances affect the individual fitness of two contrasting ungulates by examining the body mass of 378,602 roe deer (Capreolus capreolus) and Alpine chamois (Rupicapra rupicapra rupicapra) yearlings collected between 1992 and 2019 in the Eastern Alps. Transient edges had a significant positive effect on the body mass of both species. The effect size was larger for chamois than for roe deer, with yearling body mass increasing by up to 0.18 kg in female chamois for each 10 m ha-1 increase in edge density. Elevation modulated the effect of edges on chamois body mass, with a weaker effect of transient edges in high-elevation forests that are naturally more open. The effect duration of transient edges was longer for roe deer than for chamois, lasting for up to 9 years post-disturbance. The body mass effect of transient edges created by forest disturbances was an order of magnitude stronger than the effect of permanent edges between forests and other land cover types. Synthesis and applications: Increasing forest disturbances under climate change could improve the fitness of ungulates, potentially affecting forest recovery through browsing. Managers and hunting authorities should consider the effect of disturbances and dynamically changing carrying capacity of forest landscapes more explicitly when making decisions regarding habitat management and hunting policies. Such a dynamic perspective is an important element in balancing vital ungulate populations and healthy forest ecosystems.