Effects of deer on the post-fire recovery of a Mediterranean plant community in Central Portugal

Abstract

We studied the effect of dense populations of red and fallow deer on a burned Mediterranean plant community in Portugal. We sampled a set of 12 open and 12 fenced plots 2, 3, 4, and 8 years after fire occurrence. Each plot was sub-sampled using a quadrat grid to estimate the relative plant frequency (proportion of quadrats with plants). The effect of deer on temporal trends of overall plant frequency and diversity, and on the abundance of the four most common woody species, was modeled using Generalized Linear Mixed Models. The effect of deer on plant assemblage composition was assessed by use of Redundancy Analysis. In open plots the relative plant frequency increased along the study period from 0.59 to 0.85, whereas in fenced plots there was a significantly faster recovery from 0.35 to 0.96. Cistus salvifolius and Rubus ulmifolius were significantly favored by fencing but a similar effect was not observed for Erica scoparia and Ulex jussiaei. The Redundancy Analysis showed a divergent floristic composition of the two sets of plots. The effect of deer was significant for the Evenness index but not for the Shannon and the Richness indices. Our results show that a high deer density may significantly delay the post-fire recovery of a Mediterranean community of woody plants and cause shifts in the direction of plant succession.