diversity

The New Zealand Ecological Society (NZES) was formed in 1951 by government and academic researchers keen to foster the newly emerging discipline of ecology. NZES membership has now expanded to include many different contributors to ecology and conservation, from research scientists to conservation practitioners through to environmental policy analysts. Our aim was to examine how diversity in NZES has changed over time, either as a leader or a follower of trends in society.

Insect communities from a range of successional vegetation stages on the central North Island volcanic plateau were characterised and compared using Malaise trapped beetle samples. Results were derived from sampling series conducted in a total of ten sites over three separate summers. Divisive classification successfully grouped samples according to four main habitat types despite temporal and spatial separation of samples within these groups. A four-week period in early summer was found to be optimum for sample discrimination according to the main vegetation types.

The challenge of community restoration is to understand and exploit the principles of ecological succession at all seral stages, by complementing and accelerating the processes of colonisation and regeneration. The main aim is to construct self-sustaining,appropriate communities, connected in the landscape, that meet conservation, landscape and crop production goals. Research, to date, has been biased towards the plant and soil components with little consideration for the animal element.

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.

Spider assemblages were sampled by quantitative sampling in pasture and arable habitats under different management regimes in the lower North Island of New Zealand. Density and species diversity increased with decreasing frequency and/or intensity of disturbance from two species and 1.8 individuals per m in wheat to 16 species and 130 indiv. per m in an abandoned, ungrazed pasture. The spider fauna was dominated by introduced species of money spiders (Linyphiidae). The most abundant species, Lepthyphantes tenuis, is also the most abundant one in British cultivated habitats.

The relevance of Connell's Intermediate Disturbance Hypothesis (IDH) to explanations of diversity and co-existence among plant species generally and in the phytoplankton in particular has been debated recently.

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.

The 'Intermediate Disturbance Hypothesis' (IDH) is one mechanism suggested to explain indefinite species coexistence. Hutchinson's original concept of the IDH was of a mechanism based on patch dynamics, and logical consideration shows that IDH works only if interpreted this way. Dependence on patch dynamics distinguishes IDH from Gradual Climate Change (GCC), though they are distinct also in terms of premature death of individuals, species selectivity, and the suddenness and transience of the perturbation.

A Nothofagus-dominated rainforest in eastern Fiordland, New Zealand, was sampled by shoot frequency in contiguous 1 x 1 m quadrats, along a topologically-circular transect. The data were analysed at five scales up to 5 x 1 m, to search for assembly rules, i.e., generalised restrictions on species co- occurrences. There was no evidence of niche limitation in terms of the whole community, at any scale examined. Rather, variance in species richness was greater than expected from a null model, suggesting environmental heterogeneity. This conclusion was confirmed by using a patch-model.

Vocalisations are important for territorial defence, mate attraction, and species recognition in many songbirds. Comparative studies on the songs of birds between islands and mainland populations provide insight into the evolution of vocal communication in terms of both ecological and social factors. We compared the vocalisations of tui (Prosthemadera novaeseelandiae novaeseelandiae), an endemic honeyeater from New Zealand’s mainland, with those of a subspecies from the remote Chatham Islands (P. n. chathamensis).