Ungulate browsing on conifers during summer as revealed by DNA

Young trees are particularly vulnerable to browsing by ungulates, since most, or all, of their canopies are within browsing height. In tree species with strong apical dominance, browsing may also affect the structural development of the tree, causing impaired timber quality. Across Sweden, ungulate communities comprise multiple coexisting species, making it a challenge to determine which herbivore species have caused the browsing damages. However, correct identification of the culprits is pivotal for the appropriate management actions to be undertaken. In central Sweden, forest plantation owners recently reported a perceived increase in browsing damages on conifers, primarily Scots pine (Pinus sylvestris). Concurrent with this increase in browsing damages, they noticed an increase in the population of red deer in the area, leading them to suspect that the red deer (Cervus elaphus) were the primary browsers responsible for the damages. Browsed twig samples were sent to us so that we could identify the responsible browsing species using DNA. We discovered that 73.7% of the damages were actually attributable to moose (Alces alces) with 24.7% caused by red deer and 1.5% by fallow deer (Cervus dama). DNA diagnostics can thus yield important information regarding multispecies assemblages enabling managers to correctly identify the relative contributions of different species to browsing damages.