Joy, M.K. & Death, R.G. (2003) Assessing biological integrity using freshwater fish and decapod habitat selection functions. Environmental Management, 32, 747–759.
To assess human impacts on aquatic systems worldwide the comparison between observed and expected biological communities has been used successfully with predictive models. We developed a methodology based on the comparison between observed and expected freshwater fish and macro-crustacean assemblages to assess the biological quality of stream sites in the Auckland region, New Zealand. Individual discriminant models based on the presence or absence of the 12 most common fish and decapod species were developed. Using the models, predictions were made using environmental measures at new sites to yield the probability of the capture of each of the 12 species and these were combined to predict the assemblage expected at sites. The expected assemblage was compared to that observed using an observed over expected ratio (O/E). The models were evaluated using a number of internal tests including jackknifing, data partitioning and the degree to which O/E values differed between reference sites and a set of sites perceived to be impaired by human impacts.
02 December, 2003
Pierce and Westbrooke (2003): Call count responses of North Island brown kiwi to different levels of predator control in Northland, New Zealand.
Pierce R.J.; and Westbrooke I.M. 2003. Call count responses of North Island brown kiwi to different levels of predator control in Northland, New Zealand. Biological Conservation 109: 175–180.
This paper evaluates whether there are any trends in call counts that relate to predator control and advocacy in and around 23 kiwi listening stations monitored in Northland since 1995. Both predator and advocacy effort were rated on a 0ñ3 scale at each listening station, and kiwi calling rates analysed in a generalised linear model. An ANOVA indicated a positive response of call counts to predator control. There was a weaker relationship with advocacy, but because predator control and advocacy are correlated, it was not possible to separate their effects. Overall, the analysis suggested that this kind of management is benefiting kiwi in Northland.
This paper evaluates whether there are any trends in call counts that relate to predator control and advocacy in and around 23 kiwi listening stations monitored in Northland since 1995. Both predator and advocacy effort were rated on a 0ñ3 scale at each listening station, and kiwi calling rates analysed in a generalised linear model. An ANOVA indicated a positive response of call counts to predator control. There was a weaker relationship with advocacy, but because predator control and advocacy are correlated, it was not possible to separate their effects. Overall, the analysis suggested that this kind of management is benefiting kiwi in Northland.
Husheer et al. (2003): Long-term influences of introduced deer on the composition and structure of New Zealand Nothofagus forests.
Husheer, S.W.; Coomes, D.A.; Robertson, A.W. 2003. Long-term influences of introduced deer on the composition and structure of New Zealand Nothofagus forests. Forest Ecology and Management 181: 99-117.
This study uses data from ninety-two 20 m x 20 m permanent plots and three pairs of exclosure plots monitored for two decades in Kaimanawa Forest Park. Mountain beech forest composition has shifted towards browse-resistant shrub species, while intense deer browsing may have led to the development of turf-forming communities. In red and silver beech forests there was an increase in the stem densities of small trees that are unpalatable to deer. This is the first time in New Zealand that observed deer impacts in the understorey have been clearly related to changes in overstorey composition on a landscape scale.
This study uses data from ninety-two 20 m x 20 m permanent plots and three pairs of exclosure plots monitored for two decades in Kaimanawa Forest Park. Mountain beech forest composition has shifted towards browse-resistant shrub species, while intense deer browsing may have led to the development of turf-forming communities. In red and silver beech forests there was an increase in the stem densities of small trees that are unpalatable to deer. This is the first time in New Zealand that observed deer impacts in the understorey have been clearly related to changes in overstorey composition on a landscape scale.
McAlpine and Drake (2003): The effects of small-scale environmental heterogeneity on seed germination in experimental treefall gaps in New Zealand.
McAlpine, K. G.; Drake, D. R. 2003. The effects of small-scale environmental heterogeneity on seed germination in experimental treefall gaps in New Zealand. Plant Ecology 165: 207–215.
Seed germination of native and exotic woody species was studied in treefall gaps to assess how environmental heterogeneity affects regeneration from seed. Gaps were created in a relictual pine plantation destined for restoration to native forest. Seeds of Alectryon excelsus, Macropiper excelsum, Fuchsia excorticata, Cytisus scoparius and Berberis darwinii were sown in sites differing in exposure, with and without 3 cm of pine litter. Effects of litter and degree of exposure on germination varied with species. Results suggest that microenvironmental heterogeneity can be an important influence on the species composition of regenerating vegetation within and around treefall gaps.
Seed germination of native and exotic woody species was studied in treefall gaps to assess how environmental heterogeneity affects regeneration from seed. Gaps were created in a relictual pine plantation destined for restoration to native forest. Seeds of Alectryon excelsus, Macropiper excelsum, Fuchsia excorticata, Cytisus scoparius and Berberis darwinii were sown in sites differing in exposure, with and without 3 cm of pine litter. Effects of litter and degree of exposure on germination varied with species. Results suggest that microenvironmental heterogeneity can be an important influence on the species composition of regenerating vegetation within and around treefall gaps.
Gillman and Ogden (2003): Seedling mortality and damage due to non-trophic animal interactions in a northern New Zealand forest.
Gillman, L.N. & Ogden, J. 2003. Seedling mortality and damage due to non-trophic animal interactions in a northern New Zealand forest. Austral Ecology 28: 48-52.
The influence of mammal browse on indigenous tree seedlings has been extensively studied in New Zealand. However, the importance of non-trophic damage by animals (such as biting and uprooting without consump-tion) has received little attention. In this study, seedling mortality due to non-trophic animal damage (37.5% of all mortalities) was greater than for any other cause. Most of the seedlings non-trophically damaged were bitten off close to the ground and left uneaten (73%), and the remainder were uprooted. Evidence is presented that suggests that the non-trophic damage to these seedlings was caused by rabbits.
The influence of mammal browse on indigenous tree seedlings has been extensively studied in New Zealand. However, the importance of non-trophic damage by animals (such as biting and uprooting without consump-tion) has received little attention. In this study, seedling mortality due to non-trophic animal damage (37.5% of all mortalities) was greater than for any other cause. Most of the seedlings non-trophically damaged were bitten off close to the ground and left uneaten (73%), and the remainder were uprooted. Evidence is presented that suggests that the non-trophic damage to these seedlings was caused by rabbits.
Gill (2003): Osteometry and systematics of the extinct New Zealand ravens (Aves: Corvidae: Corvus).
Gill, B. J. 2003. Osteometry and systematics of the extinct New Zealand ravens (Aves: Corvidae: Corvus). Journal of Systematic Palaeontology 1: 43-58.
Measurements of Holocene raven bones show that birds from the Chatham Islands were significantly larger than those from the South Island, which were in turn larger than North Island birds. Three taxa are recognised: the Chatham Islands raven Corvus moriorum, the North Island raven C. antipodum antipodum, and the South Island raven C. a. pycrafti. New Zealand ravens were the largest crows in the Australasian region, and the Chatham Islands raven was probably the world's fourth- or fifth-largest passerine. New Zealand ravens were strong fliers with no reduction in flying ability compared to weak-flying New Zealand birds like the kokako.
Measurements of Holocene raven bones show that birds from the Chatham Islands were significantly larger than those from the South Island, which were in turn larger than North Island birds. Three taxa are recognised: the Chatham Islands raven Corvus moriorum, the North Island raven C. antipodum antipodum, and the South Island raven C. a. pycrafti. New Zealand ravens were the largest crows in the Australasian region, and the Chatham Islands raven was probably the world's fourth- or fifth-largest passerine. New Zealand ravens were strong fliers with no reduction in flying ability compared to weak-flying New Zealand birds like the kokako.
02 March, 2003
Brockerhoff et al. (2003): Diversity and succession of vascular understory plants in exotic Pinus radiata plantation forests in New Zealand.
Brockerhoff, E.G., Ecroyd, C.E., Leckie, A.C., and Kimberley M.O. 2003. Diversity and succession of vascular understory plants in exotic Pinus radiata plantation forests in New Zealand. Forest Ecology and Management 185: 307–326.
The loss of natural forests is a global threat for biodiversity. By contrast, the area of plantation forests is increasing but their role in conservation is controversial. We studied chronosequences of Pinus radiata stands to describe the succession of vascular understorey plant communities in this novel habitat. This succession is driven by a decrease in light-demanding pioneers and an increase in shade-tolerant, later seral species. The sheltered forest environment of older stands, with their mostly indigenous forest understorey community, can have conservation benefits in regions with little remaining natural forests, but the spread of wildings needs to be managed.
The loss of natural forests is a global threat for biodiversity. By contrast, the area of plantation forests is increasing but their role in conservation is controversial. We studied chronosequences of Pinus radiata stands to describe the succession of vascular understorey plant communities in this novel habitat. This succession is driven by a decrease in light-demanding pioneers and an increase in shade-tolerant, later seral species. The sheltered forest environment of older stands, with their mostly indigenous forest understorey community, can have conservation benefits in regions with little remaining natural forests, but the spread of wildings needs to be managed.
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