Long-term impacts of an introduced ungulate in native grasslands: Himalayan tahr (Hemitragus jemlahicus) in New Zealand's Southern Alps
Jennyffer Cruz, Caroline Thomson, John P Parkes, Ingrid Gruner, David M Forsyth
BIOLOGICAL INVASIONS | SPRINGER | Published : 2017
Ungulates have been widely introduced to new locations, often increasing to high densities that impact on native plant communities. Himalayan tahr (Hemitragus jemlahicus) were introduced to New Zealand in 1904 and now occupy about 9600 km2 of the Southern Alps. Managers aim to control tahr to reduce impacts to native montane grasslands. We used a network of 111 permanent plots in eight catchments to estimate the long-term impacts of tahr on total vegetation cover and snow tussock (Chionochloa spp.) height. The proportion of sub-plots containing faecal pellets was used as a measure of tahr activity. Total vegetation cover increased during the study period but declined non-linearly with increa..View full abstract
This study was funded by the New Zealand Department of Conservation. We thank all the field staff and contractors who helped with field work, particularly Morgan Coleman (Landcare Research) and Neil Bolton (DOC). The late Phil Knightbridge was instrumental in keeping the study going long term. Kerry Weston (Department of Conservation) helped sort out the long-term datasets. A. Gormley, S. Richardson, T. Easdale and G. Norbury (all Landcare Research) and two anonymous reviewers provided helpful comments on previous versions of the manuscript.