Mammalian browsing in the Mt Cole State Forest: defining a critical browsing level and assessing the effect of multiple browsing events

摘要

This study aimed to define a critical (unacceptable) level of mammalian browsing and assess the effect of multiple browsing events on messmate (Eucalyptus obliqua) and blue gum (E. globulus) seedlings regenerating in native forest logging coupes inthe Mt Cole State Forest, western Victoria. Assuming a 50 percent reduction in growth rate in the period 4-6 mo after germination was unacceptable, mean browse scores of 2.5 and 3.1 (around 25 percent and 50 percent of biomass removed) represented an unacceptable level of browsing for messmate and blue gum seedlings respectively. A cumulative measure of browsing damage recorded over the 12 mo following germination was significantly related to height growth of seedlings for both messmate (r~2 = 0.58) andblue gum (r~2 = 0.33). The cumulative measure was more closely related to first-year growth than browsing measured 6 mo after germination. This suggests that seedlings were adversely affected by multiple browsing events, and that seedlings should be protected from damage as soon as possible after browsing has reached a critical level. Additional data at larger spatial and temporal scales are required to define a critical level of browsing with direct application to native forest management.