Long-term impacts of an introduced ungulate in native grasslands: Himalayan tahr ( Hemitragus jemlahicus ) in New Zealand’s Southern Alps

摘要: Ungulates have been widely introduced to new locations, often increasing high densities that impact on native plant communities. Himalayan tahr (Hemitragus jemlahicus) were New Zealand in 1904 and now occupy about 9600 km2 of the Southern Alps. Managers aim control reduce impacts montane grasslands. We used a network 111 permanent plots eight catchments estimate long-term total vegetation cover snow tussock (Chionochloa spp.) height. The proportion sub-plots containing faecal pellets was as measure activity. Total increased during study period but declined non-linearly with activity, most rapid decline occurring activity from low levels (i.e. highly-vulnerable relationship). Tussock height weakly function time period, strongly (a proportionate A proportional effect adult non-linear logarithmic indicate species other than tussocks highly sensitive even at very levels. conclude had significantly impacted 1990–2013. Although appears still be recovering occurred prior 1970s, managers need lower levels, to further their