Rose Allen

Vegetation change following exclusion of grazing animals in depleted grassland, Central Otago, New Zealand

. Models of semiarid vegetation dynamics were evaluated to explain changes in the grassland of interior South Island, New Zealand. Annual records were taken for six years of plant species height frequency and percentage ground cover in five plots established in 1986. One subplot at each site was fenced to exclude sheep, one to exclude rabbits and sheep, and one remained unfenced as a control. Records from 1986–1992 were analysed by ordination. The overall pattern of vegetation change shows considerable year-to-year variation. At some sites, variation in vegetation composition between years was as great as, or greater than, that between grazed and ungrazed subplots. Such variation is particularly evident in grazed vegetation, perhaps because it is under greater stress than ungrazed vegetation. At one site changes in vegetation total cover and species composition could be statistically related to rainfall during the first half of the growing season. The only general trends following cessation of grazing were for perennials to increase in frequency, and for year-to-year changes to become smaller with time. Total vegetation cover values seldom changed as a result of cessation of grazing, but tended to follow year-to-year changes in species frequency. The results do not in general support switch/state-and-transition models of semi-arid vegetation dynamics. Vegetation change follows changes in grazing and climate with little lag. This most closely conforms with the Pulse-phase dynamic model.

An assembly rule in the ground and herbaceous strata of a New Zealand rain forest

1. Lowland temperate rain forest was sampled in Fiordland, New Zealand. An assembly rule was sought in terms of relative constancy in the proportion of species from seven synusial (stratum) guilds, compared to a null model in which species associate at random. Two forest types were examined (coastal broadleaved and Nothofagus broadleaved), separately and together. 2. The results show more significances than expected on a random basis. 3. In two forest-type/synusia analyses, guild proportions were more variable than expected under the null model. For lianes this is suggested to be the result of old canopy gaps and for shrubs because of topographic variation. 4. There was significant constancy in the proportion of species from the herb synusia. This effect was seen separately in both forest types. A similar effect was seen for the ground synusia, significant when the two forest types were combined. These effects suggest that there is a limitation on the assembly of these forest communities, a constraint on species coexistence that ensures relatively constant representation from the ground and herb guilds. This represents one of the first demonstrations of an assembly rule in plant communities

A method for determining indigenous vegetation from simple environmental factors, and its use for vegetation restoration

Abstract Revegetation projects are becoming common, but there has been little use of methods for determining the indegenous vegetation of a particular site for restoration. To investigate such methods, species lists were collected from 86 forest remnants in east Otago, New Zealand. Cluster Analysis with the complement of Jaccards coefficient resulted in identification of six forest types after exclusion of one induced by human disturbance. Ten easily obtained environmental factors were collated for each site. Jackknifed Discriminant Functions Analysis could predict the forest type from the environmental information with a 60% success rate. This method could be useful for vegetation reconstruction where a strong relationship exists between physical environment and existing vegetation, where the physical environment can be characterised by easily obtainable factors, and where the sampled remnants are not highly modified or predominantly secondary vegetation. The remnants should cover the range of environments found in the area.

Midwifery education: part 3 The Northern and Yorkshire region

The Northern and Yorkshire region brought together the former Northern region and the former Yorkshire region in April 1995. Before this time there had been a period of rationalization and amalgamation which greatly reduced the number of institutions offering programmes of midwifery education.