Changes in the distribution and availability of plant fuel associated with the invasion of non-native Pinus halepensis in high-altitude grasslands of Argentina

Abstract

In Argentina, near the Sierra de los Comechingones, the exotic tree P. halepensis has been used mainly as an ornamental garden tree for more than a century. However, a few years ago, scattered populations began to be observed on the slopes of the hills, which are growing rapidly. The objective of this study was to evaluate changes in the amount and distribution of combustible plant material to infer potential changes in fire behavior and in the physical structure of native communities. We performed fuel characterization following the point intercept method in three pine populations and three adjacent non-invaded grassland communities. Vertical fuel distributions were significantly different between the two types of communities (KS = 0.78, p < 0.01), and horizontal fuel continuity was also significantly different between the two types of communities (KS = 0.76, p < 0.01). According to our results, the invasion of P. halepensis could potentially affect fire dynamics and characteristics in the high-altitude grassland communities of the Sierra de los Comechingones and represents a change in the physical structure of the community, since it implies a replacement of natural grasslands with the presence of some shrub species by trees that can reach a large size.