Timing of ungulate browsing and its effect on sapling height and the field layer vegetation : experimental study using seasonel exclosures during one year

Abstract: Browsing and grazing by ungulates affect the forest structure by altering species composition and affect the growth in individual trees. The purpose with this study is to investigate the ungulate species composition visiting the clear cut, how timing of browsing affects the height increment in deciduous and conifer saplings, and how deer grazing affects the field layer coverage and height. I used seasonal exclosures in ten clear-cuts where I took data on deer visitation using camera traps, field layer vegetation coverage and height, and also height and browsing pressure on individual saplings. Each site had one permanent exclosure, one exclosure which was closed in winter but open in summer, one exclosure which was open in winter but closed in summer and one control plot which was never fenced off. The majority of the ungulates were fallow deer which shoved a higher visitation rate during summer than winter. Permanent exclosures and exclosure which were closed in summer had the highest height increment for deciduous trees. The difference in field vegetation height between 2015 and 2016 showed an effect of deer visitation rate per site but not for treatment. Browsing during summer lowered the height increment in deciduous saplings compared to winter browsing. It’s too early in this experiment to make conclusions on conifers but it seems that the timing is not as important factor as it is for deciduous saplings regarding to height development.