Mammalian herbivores are important drivers of plant species composition in forests, and at high densities of herbivore browsing pressure can have effects on regeneration of tree species, including mortality of saplings, and lead to a dominance of one understorey plant species (usually a species tolerant to browsing). In production forests herbivory can have detrimental effects on timber quality and success of regeneration stages. Existing empirical evidence for the effect of forest plant species diversity is scare and largely comes from observational studies or small feeding trial experiments. As most mammal herbivores are generalists it is predicted trees and woody plants will be more susceptible to browsing when growing in an environment with more plant species (i.e. food sources). This task will try to elucidate the links between forest characteristics and mammalian herbivory and whether the potential increase in herbivory outwieghs other benefits of forest diversity such as resistance to insect herbivores. Mammal herbivores present in the Polish exploratory: Moose (Alces alces), European bison (Bison bonasus), Red deer (Cervus elaphus), Roe deer (Capreolus capreolus), Fallow deer (Dama dama), and Wild boar (Sus scrofa).

At each plot mammalian browsing on tree saplings and other woody plant species is assessed in four subplots (5m x 5m). Per browsed plant the percentage of available shoots browsed is estimated, and the lower and upper height limits of browsed twigs recorded. Plant diamter is recorded. Additionally per subplot all woody species are identified and the number of individuals and percentage cover per species recorded. At each plot phytometers of Task II.3 are assessed for browsing damage and/or removal by wild boar. At the plot level faecal pellet groups are counted and GPS marked, and wild boar rooting depth and percentage area of plot rooted have been recorded.

Bialowieza National Park, Poland

Are there circumstances that explain the precision of your measurements? Could it be that a sandstorm destroyed part of the plots in a given year?