Population density and plant availability interplay to shape browsing intensity by roe deer in a deciduous forest

Le fichier de l'article vient de bioRxiv preprint doi : https://doi.org/10.1101/2021.11.25.468041 ; this version posted November 25, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-ND 4.0 International license (http://creativecommons.org/licenses/by-nd/4.0/)L'article publié comporte 6 p. ; International audience ; Browsing damage in forests relies on a complex interaction between herbivore density and forest understory composition and relative availability. Although variation in the amount of browsed twigs is sometimes used to assess abundance of large herbivores, the potential confounding effect of resource availability on this relationship has not been investigated yet. To fill the gap, we measured how browsing intensity of the woody plants varied in response to changes in both roe deer (Capreolus capreolus) abundance and vegetation availability from an intensive long-term monitoring. We estimated plant availability and consumption by roe deer from a modified Aldous method throughout a 14 year-long period during which we experimentally manipulated population density. The functional response was strongly non-linear and density-dependent. When plant availability was low (<12.5%), browsing intensity strongly increased with plant availability with an increasing rate of roe deer density, whereas beyond this threshold, browsing intensity slightly increased with both plant availability and population density in an additive way. Thus, forest susceptibility to browsing increases with increasing competition for food, especially when plant availability is low. Moreover, the interplay between browsing intensity and population density at low plant availability prevents the use of browsing intensity to monitor roe deer abundance when plant availability is low. Our findings provide clear evidence that relying on key ecological concepts such as functional ...