EFFECTS OF SEASON AND INTENSITY OF SHEEP GRAZING ON TREE REGENERATIONIN A BRITISH UPLAND WOODLAND

This paper reports some effects of experimental alteration of season ( summer, winter) and intensity of sheep grazing on tree regeneration, g rowth and browsing damage in an upland broadleaved woodland in Cumbria , UK. During the first 3 years of grazing treatments, seedling recruit ment was primarily Betula pubescens, Sorbus aucuparia and Fraxinus exc elsior. After 7 years of grazing treatments, seedlings and saplings of many species were numerous, with fewer seedlings in winter-grazed plo ts but a higher proportion of these were browsed. More seedlings had r eached sapling stage in winter-grazed plots. Sapling numbers increased with decreasing grazing intensity, with lower proportions browsed at low grazing intensities. Within the first 3 years grazing treatments, recruitment of Betula pubescens seedlings was greater in grazed than u ngrazed plots, and greater in winter-grazed than in summer-grazed plot s. Browsing damage to these seedlings increased with gazing intensity in winter, and height increments were greatest in ungrazed plots. Afte r 7 years, B. pubescens seedlings and saplings showed no significant t reatment effects. After 3 years, recruitment of Sorbus aucuparia seedl ings was greater in grazed than ungrazed plots, and greater in summer- grazed than winter-grazed plots. Fewer seedlings were browsed in low g razing intensity plots, and seedling height increments were greatest i n ungrazed plots. After 7 years, more S. aucuparia seedlings were brow sed in winter than summer, but saplings showed no treatment effects. A fter 3 years, recruitment of F. excelsior was greatest in low grazing intensity plots and smallest in medium gazing intensity plots. More se edlings were browsed at higher grazing intensities, but in summer-graz ed plots height increments tended to be greatest in the most heavily g razed plots. After 7 years, F. excelsior seedlings were more numerous in summer-grazed plots but were not differentially browsed; sapling nu mbers were not affected by gazing treatments but browsing damage was v ery high in all except summer low grazing plots. The implications of t he results are discussed in relation to woodland grazing management is sues.