rainfall

The unique relationship between Dactylanthus taylorii and its pollinator, the New Zealand lesser short-tailed bat (Mystacina tuberculata), is poorly understood despite both species being threatened. We used data collected over two summers (2016 and 2017) to determine if mean ambient temperature and total daily rainfall during the flowering period affected flower visitation by bats. We placed dataloggers around D. taylorii inflorescences to monitor bats with implanted passive integrated transponders (PIT-tags).

Vegetation on 5 km (c. 100 ha) of the braided bed of the Orongorongo River, Wellington, was sampled in March from 1973 to 1990. The riverbed has become aggraded since an earthquake in 1855. Surface water covered little of the riverbed; Callitriche stagnalis was the only common vascular aquatic plant. Most grasses and dicot herbs were adventive. The scabweed Raoulia tenuicaulis was the commonest dicot. The extent of plant cover was measured on 300 circular plots (radius 1.5 m); it ranged between years from 5% to 22%, depending on the severity of floods.

During the last 1800 years there have been eight periods of increased erosion and alluvial sedimentation in New Zealand, which have generally decreased in magnitude towards the present. Throughout New Zealand, alluvium of all erosion periods contains abundant remains of plants as evidence of widespread destruction of vegetation during erosion periods. Indices of the relative magnitude of alluviation, and estimates of the damage to vegetation in the current Waipawa Period (since 1950), are applied to estimate the impact of earlier erosion periods.