Benefits of aerial 1080 possum control to tree fuchsia in the Tararua Range, Wellington

The Department of Conservation established tree fuchsia (Fuchsia excorticata) monitoring in the Tararua Range in 1994 to determine the effectiveness of large-scale (66 000 ha) possum control for protecting fuchsia. We present results from data collected from 39 permanent plots on fuchsia tree stem survival, growth, and canopy condition between 1994 and 2004 using standard permanent plot and foliar assessment methods. Plots were established in four areas where possums were controlled or treated by aerial application of sodium monofluoroacetate (1080) poison, and in one untreated area. More fuchsia stems died in the untreated area (29.8%) than in the treated areas combined (mean of 7%) over the duration of the study. Stem mortality was offset by a mean 3% (+ 1.1% SEM) increase in fuchsia basal area in the treated areas, whereas basal area declined by 15% in the untreated area. Stem mortality occurred largely in smaller size-classes (<21 cm diameter) in all areas. Mean foliar cover showed a greater decline (42%) in the untreated area than in the treated areas (range 0 to 26%). Within two of the four treated areas, foliar cover declined as the interval between possum control operations lengthened. Our results clearly show that the conservation goal of preventing 25% mortality of tree fuchsia between 1994 and 2004 was successfully achieved in upland possum control areas.