vegetation

Vegetation succession (1967-89) on five recent montane lava flows, Mauna Loa, Hawaii

Vegetation succession on 4 recent (1852-1942) montane lava Rows on Mauna Loa, Hawaii, was remeasured 22 years after the first measurement in 1967. Colonisation patterns of vascular plant species were observed on a new lava flow (1984) which overwhelmed part of the earlier studied 1852 flow. An influx of adventive species, positively correlated with flow age, was noted at the remeasured sites; most were herbs and grasses that do not appear to interfere with the succession to Metrosideros- dominated forest.

Spatiotemporal scales of non-equilibrium community dynamics: A methodological challenge

The Intermediate Disturbance Hypothesis [IDH] and the Gradual Climate Change Hypothesis [GCC] offer intuitively appealing, verbal non-equilibrium explanations to species coexistence in competitive communities, but so far they lack a solid theoretical background and a proper experimental methodology. To make them testable and comparable on a solid methodological basis, they should be formulated as well-defined non- equilibrium community dynamical models.

The distribution and abundance of Hieracium species (hawkweeds) in the dry grasslands of Canterbury and Otago

We examined the distribution and abundance of the invasive Hieracium species (hawkweeds) in the dry grasslands of the Upper Waitaki Basin (Canterbury) and Otago, using measures of Hieracium species frequency and hawkweed cover from 301 vegetation plots. Average hawkweed cover was significantly less in Otago than Canterbury. Hawkweed cover was also lower on drier sites, with hawkweeds having less cover at lower elevation, on more xeric sites and, in Canterbury, on soils with a lower moisture holding capacity.

Short-term effects of rabbit grazing on a degraded short- tussock grassland in Central Otago

Rabbits are serious economic and environmental pests in New Zealand's semi arid lands, yet there is surprisingly little quantitative information about their grazing impacts. This paper describes the shortterm gains in pasture yield following protection from rabbit grazing in a rabbit-prone, dry tussock grassland community in Central Otago. During the four most productive plant growing months of 1994 (September to December), a six-fold increase in pasture yield was observed after protection from rabbit grazing (139 kg dry weight ha(-1) with rabbits cf. 853 kg DW ha(-1) without rabbits).

Effects of habitat structure on distribution and abundance of lizards at Pukerua bay, Wellington, New Zealand

The distribution and abundance of lizards relative to habitat structure were studied at Pukerua Bay, Wellington between December 1982 and March 1988 in order to identify options for management of the habitat of the five species of lizards present. One species, Whitaker's skink (Cyclodina whitakeri), is a threatened species with only one known mainland population. Pitfall traps were set for 23 667 trap-days and yielded 2897 lizard captures. Highest capture rate was for common skinks (Oligosoma nigriplantare polychroma) and lowest rate was for C. whitakeri.

A test of the humped-back theory of species richness in New Zealand native forest

The Humped-back theory of plant species richness, a theory related to Grime's C-S-R 'triangular' model, has been widely discussed, and some evidence has been claimed in support of it. The theory suggests that species richness is maximal at intermediate levels of productivity, i.e., at intermediate positions on a stress/favourability gradient. We sought evidence for the theory from 90 stands of native podocarp/broadleaved and beech forest in the Coastal Otago region, with an adjustment made for the effect of stand area on species richness.

The ecology of Dactylanthus taylorii and threats to its survival

Dactylanthus taylorii, a root parasite in the family Balanophoraceae, is New Zealand's only fully parasitic flowering plant. It grows attached to the roots of a wide range of hardwood trees and shrubs, often in fire-induced secondary forest on the margin of podocarp-hardwood forest. It is inconstantly dioecious with a skewed sex ratio of approximately 5:1 male to female inflorescences. The inflorescences, especially the males, contain a large quantity of nectar, up to 1.6 mi, and can produce 0.5 mi per day for 10 days.

Environmental correlates of species richness at Waipoua Forest Sanctuary, New Zealand

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.

Vegetation—a Mosaic of Discrete Communities, or a Continuum

A simulation model, using the often observed log-linear relationship between the relative abundance and rank of species, shows that vegetation will tend to form a series of communities of constant composition along an environmental gradient even if the constituent species are initially responding independently to those environmental changes. The discreteness of these communities increases with increasing conformity to the log-linear relationship. An index quantifying this conformity (range 0-1.0) is defined and a method for estimating it from field vegetation data devised.

The Vegetation of Sub-Antarctic Campbell Island

The vegetation of Campbell Island and its offshore islets was sampled quantitatively at 140 sites. Data from the 134 sites with more than one vascular plant species were subjected to multivariate analysis. Out of a total of 140 indigenous and widespread adventive species known from the island group, 124 vascular species were recorded; 85 non-vascular cryptogams or species aggregates play a major role in the vegetation. Up to 19 factors of the physical environment were recorded or derived for each site.