weed management

Removing wilding conifers (invasive non-native trees in the Pinaceae) has become a major focus of conservation and land management in Aotearoa New Zealand. Management of wilding conifers has been supported by applied research on control methods, generally with a short-term focus of removing or containing invasions to prevent further spread. However, a focus on short-term management activities may not achieve desired longer-term outcomes of restoring economic and environmental values.

Climate change may exacerbate the impacts of plant invasions by providing opportunities for new naturalisations and for alien species to expand into regions where previously they could not survive and reproduce. Although climate change is not expected to favour invasive plants in every case, in Aotearoa-New Zealand a large pool of potential new weeds already exists and this country is predicted to be an ‘invasion hotspot’ under climate change.

It is common practice in New Zealand dryland areas to chemically or mechanically control invasive woody weeds, including Scotch broom (Cytisus scoparius). Such weed control is not always effective in achieving the often implicit aim of advancing the restoration of indigenous woody vegetation. We used a field experiment on a braided river terrace on the Canterbury Plains to test how five different management treatments of broom cover affected the germination, survival and growth of six indigenous tree and shrub species in a dryland setting.