flora

At non-rocky sites on the shorelines of Lakes Manapouri and Te Anau floristic composition was recorded for one-foot intervals of elevation above and below lake level. Mean daily levels recorded since 1932 have been analysed to find the longest periods of submergence and emergence experienced at each level. A hypothesis that species distribution is governed by extremes of submergence and emergence is supported by the similar periods recorded at the limits of each species at both lakes.

Native birds may have been underestimated as pollinators of the New Zealand flora due to their early decline in abundance and diversity on the mainland. This paper reconsiders the relative importance of birds and insects as pollinators to eight native flowering plants, representing a range of pollination syndromes, on two offshore island refuges. Experimental manipulations were made on five of these plant species to assess the relative effectiveness of bird and insect visitors as pollinators.

There are at least three hypotheses to account for the abundance of divaricating shrubs in New Zealand: 1) Ratites in the form of 11 species of moa, led to divarication for browse protection (Greenwood and Atkinson, 1977); 2) Divarication evolved as a microclimatic shield (McGlone and Webb, 1981); 3) Divarication evolved to aid leaves in light harvesting (Kelly, 1994). In Patagonia before human arrival, there were browsing mammals in addition to the ratite rhea.

Hihi (or stitchbird, Notiomystis cincta) is a rare honeyeater endemic to the North Island of New Zealand. Hihi were translocated from Little Barrier Island to Mokoia Island, Lake Rotorua, in 1994. Mokoia is a small (135 ha) island with secondary vegetation, so there was some doubt as to whether the island had sufficient diversity of fruit and nectar sources to support a hihi population. This paper reports data collected in the year after the translocation on the density, distribution and phenology of plants likely to be used by hihi. We address the following questions.

Fuchsia (Fuchsia excorticata) has been heavily browsed and often killed by brushtail possums (Trichosurus vulpecula) in many New Zealand indigenous forests, but remains healthy at some sites despite long histories of possum occupation. To determine whether fuchsia varied genetically in its palatability to possums, material from six widely dispersed stands (provenances) was propagated, and leaf chemistry, leaf morphology, growth rate, and palatability to captive possums was compared.

To determine the susceptibility of different forest types to lianes, and to investigate which ecological factors are limiting for lianes, a field survey covering 28 naturally forested sites in Golden Bay (Northwest Nelson) and on Banks Peninsula (Canterbury) was carried out. Results from Detrended Canonical Correspondence Analysis of liane species abundance data in relation to tree and shrub species abundance data and abiotic site variables, showed that the liane community composition was highly correlated with the composition of the tree and shrub community.

Descriptions of 247 forest stands at Waipoua Forest, Northland, were used to explore relationships between species richness (alpha-diversity) of the vascular flora and stand environmental characteristics, both in terms of total flora and within a number of the component synusiae. The Waipoua forests, with an average of 52 species per forest stand, are comparatively species-rich compared to other New Zealand forests.

Pronounced differences between the vegetation of four islands in a low-alpine lake compared to an adjacent mainland site are attributed to browsing by feral goats. The herbs Anisotome haastii and Ourisia macrocarpa are significantly more abundant on the islands, where they form tall herbfields. The grass Hierochloe recurvata and the shrub Gaultheria crassa were also more common on the islands, and were absent at the mainland study site.

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.

The ability of feral goats to become pests is partly a consequence of the process of domestication. Neolithic people selected biological characteristics from wild goats, such as higher intrinsic rates of increase and increased sociability that have resulted in their domestic descendants becoming a particular nuisance when they escape to become feral. Feral goats live in about 11 % of New Zealand, mostly on land reserved for conservation of the indigenous biota. Their uncontrolled densities are usually less than 1 ha-1, but have reached 10 ha-1 in one area.