The effects of moose (Alces alces L.) on hemlock (Tsuga canadensis (L.)Carr.) seedling establishment in Algonquin Provincial Park, Ontario, Canada

The effects of moose on eastern hemlock (Tsuga canadensis) natural seedling establishment in Algonquin Provincial Park, Ontario, were examined. Two thousand seedlings were tagged on 56 sites in 1992 and monitored for six years. Initial data collected included seedling height, browsing history and percent crown closure. At the end of the growing season of the following six years, heights of these seedlings were remeasured; damages on seedlings were assessed according to browsing, physical, logging and unknown factors. After six years, 10.4% of the seedlings had died. Browsing caused 60% of the mortality, followed by unknown factors (18%). Growth rates of healthy, unbrowsed seedlings were significantly affected by initial height, health and percent crown closure. Growth was best at 60% crown closure and least at 80% to 100% crown closure. Healthy, undamaged seedlings grew better than seedlings with browse damage, dieback or both. Mean height losses were 11.1 cm with each browsing incident. Growth Fates indicated that seedlings may need to avoid being browsed for up to 30 years to ensure leaders are out of the reach of moose. A negative correlation between moose density and browsing suggested that low moose density in recent years may provide a better opportunity for establishment and canopy recruitment.