Urlich, S.C.; Stewart, G.H.; Duncan, R.P.; Almond, P.C. 2005. Tree regeneration in a New Zealand rain forest influenced by disturbance and drainage interactions. Journal of Vegetation Science 16: 423–432.
Question: Does canopy tree regeneration response to difference large disturbances vary with soil drainage?
Location: Old-growth conifer (Dacrydium and Dacrycarpus), angiosperm (Nothofagus and Weinmannia) rain forest, Mount Harata, South Island, New Zealand.
Methods: Trees were aged (1056 cores) to reconstruct stand history in 20 (0.12–0.2 ha) plots with different underlying drainage. Spatial analyses of an additional 805 tree ages collected from two (0.3–0.7 ha) plots were conducted to detect patchiness for five canopy tree species. Microsite preferences for trees and saplings were determined.
Results: There were clear differences in species regeneration patterns on soils with different drainage. Conifer recruitment occurred infrequently in even-aged patches (>1000 m2) and only on poorly drained soils. Periodic Nothofagus fusca and N. menziesii recruitment occurred more frequently in different sized canopy openings on all soils. Weinmannia recruitment was more continuous on all soils reflecting their greater relative shade-tolerance. Distinct periods of recruitment that occurred in the last 400 years matched known large disturbances in the region. These events affected species differently as soil drainage varied. Follow- ing earthquakes, both conifer and N. menziesii regenerated on poorly drained soils, while Nothofagus species and Weinmannia regenerated on well drained soils. However, Dacrydium failed to regenerate after patchy storm damage in the wetter forest interior; instead faster growing N. fusca captured elevated microsites caused by uprooting.
Conclusions: Underlying drainage influenced species composition, while variation in the impacts of large disturbance regulated relative species abundances on different soils.
02 October, 2005
Gillman and Ogden (2005): Microsite heterogeneity in litterfall risk to seedlings.
Gillman, L. N., and J. Ogden. 2005. Microsite heterogeneity in litterfall risk to seedlings. Austral Ecology 30:497–504.
Litterfall is an important cause of damage and mortality to seedlings in many forests. However, this study is the first to demonstrate variable risks of litterfall damage among different microsites. Artificial seedlings were ‘planted’ along transects in each of two New Zealand forests, and the overhead species recorded. The artificial seedlings were monitored monthly for damage over two years. The risk of damage differed significantly among microsites from 2% to 30% per y (P < 0.0005). Seedlings differ in resilience to litterfall (Gillman et al. 2003) and, therefore, microsites with different litterfall risks provide the potential for regeneration niche differentiation.
Litterfall is an important cause of damage and mortality to seedlings in many forests. However, this study is the first to demonstrate variable risks of litterfall damage among different microsites. Artificial seedlings were ‘planted’ along transects in each of two New Zealand forests, and the overhead species recorded. The artificial seedlings were monitored monthly for damage over two years. The risk of damage differed significantly among microsites from 2% to 30% per y (P < 0.0005). Seedlings differ in resilience to litterfall (Gillman et al. 2003) and, therefore, microsites with different litterfall risks provide the potential for regeneration niche differentiation.
02 June, 2005
Willis and Millar (2005): Using marine reserves to estimate fishing mortality.
Willis, T.J. & R.B. Millar (2005) Using marine reserves to estimate fishing mortality. Ecology Letters 8: 47–52.
The pervasive effects of fishing mean that what is generally seen on our coasts is not ‘natural’. Here we demonstrate how no-take marine reserves, where all forms of human-induced disturbance are forbidden, can be used to estimate fishing mortality independently of the fishery. We suggest that reserves can be used to estimate other important population parameters in exploited marine species. Reserves can be used to combat the ‘shifting baseline’ syndrome and provide controls for determining what is natural in the oceans.
The pervasive effects of fishing mean that what is generally seen on our coasts is not ‘natural’. Here we demonstrate how no-take marine reserves, where all forms of human-induced disturbance are forbidden, can be used to estimate fishing mortality independently of the fishery. We suggest that reserves can be used to estimate other important population parameters in exploited marine species. Reserves can be used to combat the ‘shifting baseline’ syndrome and provide controls for determining what is natural in the oceans.
Efford and Cowan (2004): Long-term population trend of Trichosurus vulpecula in the Orongorongo Valley, New Zealand.
Efford, M. G.; Cowan, P. E. 2004. Long-term population trend of Trichosurus vulpecula in the Orongorongo Valley, New Zealand. In: R. L. Goldingay and S. M. Jackson (eds.) The biology of Australian possums and gliders. Surrey Beatty & Sons, Chipping Norton. Pp. 471–483.
Browsing by introduced brushtail possums has been predicted to shift the species composition of native forests away from palatable species, and thereby to reduce the density of possums those forests support. We tested this prediction with data from a population of possums monitored by capture–recapture over 35 years. Annual density varied within a relatively narrow band (6.5–13.7/ha) and the overall trend was slightly positive (+0.04 ± 0.025 /ha/year), despite the decline of some ‘preferred’ plant species. We speculate that possum carrying capacity was buffered against the loss of palatable plants because these were replaced by more resilient and fast-growing palatable species.
Browsing by introduced brushtail possums has been predicted to shift the species composition of native forests away from palatable species, and thereby to reduce the density of possums those forests support. We tested this prediction with data from a population of possums monitored by capture–recapture over 35 years. Annual density varied within a relatively narrow band (6.5–13.7/ha) and the overall trend was slightly positive (+0.04 ± 0.025 /ha/year), despite the decline of some ‘preferred’ plant species. We speculate that possum carrying capacity was buffered against the loss of palatable plants because these were replaced by more resilient and fast-growing palatable species.
02 March, 2005
Joy and Death (2004): Predictive modelling and spatial mapping of freshwater fish and decapod assemblages.
Joy, M.K. & Death, R.G. (2004) Predictive modelling and spatial mapping of freshwater fish and decapod assemblages: an integrated GIS and neural network approach. Freshwater Biology, 49, 1036–1052.
We used stream fish and decapod spatial occurrence data extracted from the New Zealand Freshwater Fish Database combined with recent surveys and geospatial landuse data, geomorphologic, climatic, and spatial data in a geographical information system (GIS) to model fish occurrence in the Wellington Region, New Zealand. To predict the occurrence of each species at a site from a common set of predictor variables we used a multi- response, artificial neural network (ANN), to produce a single model to predict the entire fish and decapod assemblage in one procedure. The predictions from the ANN using this landscape scale data proved very accurate and four other evaluation metrics independent of species abundance or probability thresholds also confirmed the accuracy of the model. The geospatial data available for the entire regional river network were then used to create a habitat-suitability map for all 18 species over the regional river network using GIS. This prediction map has many potential uses including; monitoring and predicting temporal changes in fish communities caused by human activities and shifts in climate, identifying of areas in need of protection, biodiversity hotspots, and areas for the reintroduction of endangered or rare species.
We used stream fish and decapod spatial occurrence data extracted from the New Zealand Freshwater Fish Database combined with recent surveys and geospatial landuse data, geomorphologic, climatic, and spatial data in a geographical information system (GIS) to model fish occurrence in the Wellington Region, New Zealand. To predict the occurrence of each species at a site from a common set of predictor variables we used a multi- response, artificial neural network (ANN), to produce a single model to predict the entire fish and decapod assemblage in one procedure. The predictions from the ANN using this landscape scale data proved very accurate and four other evaluation metrics independent of species abundance or probability thresholds also confirmed the accuracy of the model. The geospatial data available for the entire regional river network were then used to create a habitat-suitability map for all 18 species over the regional river network using GIS. This prediction map has many potential uses including; monitoring and predicting temporal changes in fish communities caused by human activities and shifts in climate, identifying of areas in need of protection, biodiversity hotspots, and areas for the reintroduction of endangered or rare species.
Joy and Death (2004): Application of the Index of Biotic Integrity Methodology to New Zealand Freshwater Fish Communities.
Joy, M.K. & Death, R.G. (2004) Application of the Index of Biotic Integrity Methodology to New Zealand Freshwater Fish Communities. Environmental Management, 34, 415–428.
An index of biotic integrity (IBI) was developed for freshwater fish in New Zealand streams. Data on freshwater fish occurrence for 5007 sites over the entire country were obtained from the New Zealand freshwater fish database for the period 1980–2002. Corresponding environmental descriptors for the stream catchments above or at each of these sites were obtained from a number of databases using a geographic information system. Of the 12 original North American IBI metrics, only six were adapted and applied because of differences between the fish faunas of New Zealand and the United States of America. A number of evaluation methods showed all six metrics contributed to the overall IBI scores with high levels of consistency. The IBI assessment of sites sampled at different times showed high levels of temporal concordance. Overall, the results presented demonstrate the potential for New Zealand freshwater fish to be used to assess river condition at large spatial scales in New Zealand in the absence of specifically selected reference sites.
An index of biotic integrity (IBI) was developed for freshwater fish in New Zealand streams. Data on freshwater fish occurrence for 5007 sites over the entire country were obtained from the New Zealand freshwater fish database for the period 1980–2002. Corresponding environmental descriptors for the stream catchments above or at each of these sites were obtained from a number of databases using a geographic information system. Of the 12 original North American IBI metrics, only six were adapted and applied because of differences between the fish faunas of New Zealand and the United States of America. A number of evaluation methods showed all six metrics contributed to the overall IBI scores with high levels of consistency. The IBI assessment of sites sampled at different times showed high levels of temporal concordance. Overall, the results presented demonstrate the potential for New Zealand freshwater fish to be used to assess river condition at large spatial scales in New Zealand in the absence of specifically selected reference sites.
02 December, 2004
Russell and Clout (2004): Modelling the distribution and interaction of introduced rodents on New Zealand offshore islands.
Russell, J.C.; Clout, M.N. 2004. Modelling the distribution and interaction of introduced rodents on New Zealand offshore islands. Global Ecology and Biogeography 13: 497–507.
Invasion of New Zealand’s offshore islands by the four introduced rodents has caused widespread damage to the native biota. Here the geographical and ecological factors that relate to their distribution on offshore islands are examined, as are interactions between their distributions. The ship rat appears most widely distributed, and the most dominant, while kiore have suffered mostly from the expansion of ship rats and to a lesser extent Norway rats. The distribution of mice remains unexplained. Their coexistence is explained by differences in competitive ability and dispersal.
Invasion of New Zealand’s offshore islands by the four introduced rodents has caused widespread damage to the native biota. Here the geographical and ecological factors that relate to their distribution on offshore islands are examined, as are interactions between their distributions. The ship rat appears most widely distributed, and the most dominant, while kiore have suffered mostly from the expansion of ship rats and to a lesser extent Norway rats. The distribution of mice remains unexplained. Their coexistence is explained by differences in competitive ability and dispersal.
Gillman et al. (2004): The influence of macro-litterfall and forest structure on litterfall damage to seedlings.
Gillman, L.N.; Ogden, J.; Wright, S.D.; Stewart, K.L.; Walsh, D.P. 2004. The influence of macro-litterfall and forest structure on litterfall damage to seedlings. Austral Ecology 29: 305–312.
Litterfall damage to forest seedlings can differentially affect the survival and recruitment of different seedling species and it is therefore likely to influence forest composition. Rates of damage to seedlings differ among, and within, forests and appear to be independent of total litterfall. However, in this study of five North Island forests we demonstrate that the rate of macro-litterfall (leaf and deadwood material >1.5 x 30cm) surface area correlates strongly to litterfall damage to artificial seedlings (R2 = 0.99, P<0.005). In addition, the risk of litterfall damage to seedlings was reduced by up to 84% by ground vegetation and lianes. These results are important because they suggest that subtle differences in species abundances, and forest structure, may influence regeneration patterns through the litterfall disturbance regime.
Litterfall damage to forest seedlings can differentially affect the survival and recruitment of different seedling species and it is therefore likely to influence forest composition. Rates of damage to seedlings differ among, and within, forests and appear to be independent of total litterfall. However, in this study of five North Island forests we demonstrate that the rate of macro-litterfall (leaf and deadwood material >1.5 x 30cm) surface area correlates strongly to litterfall damage to artificial seedlings (R2 = 0.99, P<0.005). In addition, the risk of litterfall damage to seedlings was reduced by up to 84% by ground vegetation and lianes. These results are important because they suggest that subtle differences in species abundances, and forest structure, may influence regeneration patterns through the litterfall disturbance regime.
Efford (2004): Density estimation in live-trapping studies.
Efford, M.G. 2004. Density estimation in live-trapping studies. Oikos 106: 598–610.
This paper describes a new and general method for estimating density from closed-population capture–recapture data. Simulation and inverse prediction are used to estimate jointly the population density and two parameters for a spatial model of detection. The method uses any configuration of traps (e.g., grid, web or line), and simulations show it is largely free of bias when simple assumptions are met. The paper includes two New Zealand examples: Landcare Research data on brushtail possums in the Orongorongo Valley, and Ross Pickard’s study of house mice on Mana Island. See www.landcareresearch.co.nz/services/software/density for software and a pdf of the paper.
This paper describes a new and general method for estimating density from closed-population capture–recapture data. Simulation and inverse prediction are used to estimate jointly the population density and two parameters for a spatial model of detection. The method uses any configuration of traps (e.g., grid, web or line), and simulations show it is largely free of bias when simple assumptions are met. The paper includes two New Zealand examples: Landcare Research data on brushtail possums in the Orongorongo Valley, and Ross Pickard’s study of house mice on Mana Island. See www.landcareresearch.co.nz/services/software/density for software and a pdf of the paper.
02 August, 2004
Stewart et al. (2004): The re-emergence of indigenous forest in an urban environment, Christchurch, New Zealand.
Stewart, G.H.; Ignatieva, M.E.; Meurk, C.D.; Earl, R.D. 2004. The re-emergence of indigenous forest in an urban environment, Christchurch, New Zealand. Urban Forestry & Urban Greening 2: 149-158.
In this article we examine the indigenous and exotic shrub and tree components of the Christchurch flora as planted street trees, in domestic gardens, and in parks. We also present data on tree and shrub regeneration in parks and domestic gardens in the city. Indications are that the more sensitive, less intrusive management of urban enviornments, combined with the greater density of indigenous seded sources, has already allowed regeneration of a wide range of indigenous species across a broad spectrum of habitats—from neglected gardens to pavement cracks to exotic plantations. If present trends continue through appropriate management and facilitation, native forest regeneration should proliferate into a sustainable mixed origin urban forest that resurrects and preserves the natural character of the region.
In this article we examine the indigenous and exotic shrub and tree components of the Christchurch flora as planted street trees, in domestic gardens, and in parks. We also present data on tree and shrub regeneration in parks and domestic gardens in the city. Indications are that the more sensitive, less intrusive management of urban enviornments, combined with the greater density of indigenous seded sources, has already allowed regeneration of a wide range of indigenous species across a broad spectrum of habitats—from neglected gardens to pavement cracks to exotic plantations. If present trends continue through appropriate management and facilitation, native forest regeneration should proliferate into a sustainable mixed origin urban forest that resurrects and preserves the natural character of the region.
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