The effects of Gotland pony grazing on forest composition and structure in Lojsta hed, south eastern Sweden

Abstract: Livestock animals affect their environment in a number of different ways, mostly through grazing and trampling. This study focused on the effects of Gotland pony grazing on forest structure and diversity, and the impact on ground cover. To compare the fenced and grazed area with a reference area outside the enclosure a number of transects were used. The study showed that there was no significant difference in height structure and diversity between the compared sites; however, there were a significantly higher proportion of damaged trees inside the enclosure. The ground cover variables showed a higher amount of bare soil, plant litter and wood-rush (Luzula sp.) inside the enclosure whilst grass was more frequent in the reference area. This is probably promoting disturbance-tolerant species. However, the results do indicate that the higher amount of grazing might be homogenizing the forests undergrowth. The implications of this study suggest that the way the horses are kept need to be modified in order to continue to maintain the desired open forest structure. Due to the lack of knowledge on the horses’ effect on ecosystem functions further studies on other taxa is advisable as well.