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.
02 December, 2004
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.
02 June, 2004
Willis et al. (2003): Protection of exploited fishes in temperate regions: high density and biomass of snapper Pagrus auratus.
Willis, T.J.; Millar, R.B.; Babcock, R.C. 2003. Protection of exploited fishes in temperate regions: high density and biomass of snapper Pagrus auratus (Sparidae) in northern New Zealand marine reserves. Journal of Applied Ecology 40: 214–227.
Rigorous empirical evidence for the recovery of exploited species within ‘no-take’ marine reserves is limited, especially in temperate regions. The relative density and size structure of snapper Pagrus auratus: Sparidae, were measured inside and outside three northern New Zealand marine reserves using baited underwater video every six months from October 1997 to April 1999. Snapper that were larger than the minimum legal size were estimated to be 14 times denser in protected areas than in fished areas, and the relative egg production was estimated to be 18 times higher. This species was thought to be too mobile to respond to area-based protection.
Rigorous empirical evidence for the recovery of exploited species within ‘no-take’ marine reserves is limited, especially in temperate regions. The relative density and size structure of snapper Pagrus auratus: Sparidae, were measured inside and outside three northern New Zealand marine reserves using baited underwater video every six months from October 1997 to April 1999. Snapper that were larger than the minimum legal size were estimated to be 14 times denser in protected areas than in fished areas, and the relative egg production was estimated to be 18 times higher. This species was thought to be too mobile to respond to area-based protection.
Willis et al. (2000): Detection of spatial variability in relative density of fishes.
Willis, T.J.; Millar, R.B.; Babcock, R.C. 2000. Detection of spatial variability in relative density of fishes: comparison of visual census, angling, and baited underwater video. Marine Ecology Progress Series 198: 249–260.
The ability to make accurate estimates of fish relative abundance is the basis of both ecological and environmental effects studies. This paper compares surveys of snapper and blue cod conducted using three methods (underwater visual census, experimental angling, and baited underwater video). Angling and baited video gave consistent estimates of snapper density, whereas visual surveys provided the least reliable measure, with adults only detected at locations where fish have been habituated to divers by hand feeding. Blue cod, however, were well estimated using visual census. The study indicates that methodological standardisation across all species is not always appropriate for environmental effects studies.
The ability to make accurate estimates of fish relative abundance is the basis of both ecological and environmental effects studies. This paper compares surveys of snapper and blue cod conducted using three methods (underwater visual census, experimental angling, and baited underwater video). Angling and baited video gave consistent estimates of snapper density, whereas visual surveys provided the least reliable measure, with adults only detected at locations where fish have been habituated to divers by hand feeding. Blue cod, however, were well estimated using visual census. The study indicates that methodological standardisation across all species is not always appropriate for environmental effects studies.
Willis and Anderson (2003): Structure of cryptic reef fish assemblages: relationships with habitat characteristics and predator density.
Willis, T.J.; Anderson, M.J. 2003. Structure of cryptic reef fish assemblages: relationships with habitat characteristics and predator density. Marine Ecology Progress Series 257: 209–221.
The effects of reef structural complexity, kelp density, and the density of predators on assemblages of small, cryptic reef fishes were examined in northeastern New Zealand. Sampling was conducted inside and outside of a marine reserve, which acted as a high predator density treatment. There were lower densities of cryptic fishes inside the reserve, which might be explained by effects of predators. The effect of the marine reserve was strongest in the kelp forest habitat, relative to unvegetated habitats. These results imply that removal of predators by fishing may have large-scale positive effects on assemblages of small cryptic reef fishes.
The effects of reef structural complexity, kelp density, and the density of predators on assemblages of small, cryptic reef fishes were examined in northeastern New Zealand. Sampling was conducted inside and outside of a marine reserve, which acted as a high predator density treatment. There were lower densities of cryptic fishes inside the reserve, which might be explained by effects of predators. The effect of the marine reserve was strongest in the kelp forest habitat, relative to unvegetated habitats. These results imply that removal of predators by fishing may have large-scale positive effects on assemblages of small cryptic reef fishes.
Russell et al. (2004): Island biogeography and the species richness of introduced mammals on New Zealand offshore islands.
Russell, J. C.; Clout, M. N.; McArdle, B. H. 2004. Island biogeography and the species richness of introduced mammals on New Zealand offshore islands. Journal of Biogeography 31: 653–664.
Invasion of offshore islands by mammals is a constant threat to conservation in New Zealand, However the factors that correlate with the species richness of introduced mammals on New Zealand offshore islands have never been fully investigated. Using a widespread dataset these factors (geographical, ecological and anthropological) are examined. Distance appears to have become trivial in preventing invasion except for the smallest of mammals. Most high species richness appears related to human activity. Some evidence of a ‘small island’ effect is found.
Invasion of offshore islands by mammals is a constant threat to conservation in New Zealand, However the factors that correlate with the species richness of introduced mammals on New Zealand offshore islands have never been fully investigated. Using a widespread dataset these factors (geographical, ecological and anthropological) are examined. Distance appears to have become trivial in preventing invasion except for the smallest of mammals. Most high species richness appears related to human activity. Some evidence of a ‘small island’ effect is found.
Barker (2002): Gastropods as pests in New Zealand pastoral agriculture, with emphasis on Agriolimacidae, Arionidae and Milacidae.
Barker, G.M. 2002. Gastropods as pests in New Zealand pastoral agriculture, with emphasis on Agriolimacidae, Arionidae and Milacidae. Pp. 361– 423 In: Barker, G.M. (ed.) Molluscs as Crop Pests. CAB International, Wallingford.
This chapter reviews the development of agriculture in New Zealand and the emergence of introduced herbivorous gastropods as pastoral pests. In the context of an agroclimatic classiication, the link is made between environment, land use, and ecology of the gastropod communities. The pest status of Agriolimacidae, Arionidae and Milacidae is then addressed in the context of (i) established pastures, (ii) pasture establishment, (iii) forage-seed crops, and (iv) transmission of plant pathogens.
This chapter reviews the development of agriculture in New Zealand and the emergence of introduced herbivorous gastropods as pastoral pests. In the context of an agroclimatic classiication, the link is made between environment, land use, and ecology of the gastropod communities. The pest status of Agriolimacidae, Arionidae and Milacidae is then addressed in the context of (i) established pastures, (ii) pasture establishment, (iii) forage-seed crops, and (iv) transmission of plant pathogens.
Barker (2002): Phylogenetic diversity: a quantitative framework for measurement of priority and achievement in biodiversity conservation.
Barker, G.M. 2002. Phylogenetic diversity: a quantitative framework for measurement of priority and achievement in biodiversity conservation. Biological Journal of the Linnean Society 76: 165–194.
Biodiversity option value can be equated with richness of features expressed by species. Feature diversity of communities can be predicted by the phylogenetic relationships among species. The ‘Phylogenetic Diversity’ measure (PD) estimates the relative feature diversity of any nominated set of species by the patristic or path-length distances. This study reviews and expands on some of the properties of PD, and develops simple modifications of the measure to enable capture of both the phylogenetic relatedness of species and their abundances. The application of PD concepts to a range of conservation and resource management issues is demonstrated using New Zealand avian case studies.
Biodiversity option value can be equated with richness of features expressed by species. Feature diversity of communities can be predicted by the phylogenetic relationships among species. The ‘Phylogenetic Diversity’ measure (PD) estimates the relative feature diversity of any nominated set of species by the patristic or path-length distances. This study reviews and expands on some of the properties of PD, and develops simple modifications of the measure to enable capture of both the phylogenetic relatedness of species and their abundances. The application of PD concepts to a range of conservation and resource management issues is demonstrated using New Zealand avian case studies.
Barker (2001): Gastropods on land: phylogeny, diversity and adaptive morphology.
Barker, G.M. 2001. Gastropods on land: phylogeny, diversity and adaptive morphology. Pp. 1–146 In: Barker, G.M. (ed.) Biology of Terrestrial Molluscs. CAB International, Wallingford.
This chapter provides a review of the evolutionary history of gastropods, with emphasis on terrestriality achieved independently in a number of lineages and the associated morphological and ecological radiations.
This chapter provides a review of the evolutionary history of gastropods, with emphasis on terrestriality achieved independently in a number of lineages and the associated morphological and ecological radiations.
Anderson and Wilis (2003): Canonical analysis of principal coordinates: a useful method of constrained ordination for ecology.
Anderson, M.J.; Willis, T.J. 2003. Canonical analysis of principal coordinates: a useful method of constrained ordination for ecology. Ecology 84: 511–525.
We describe a new method for constrained ordination (with reference to an a priori specified hypothesis) of multivariate ecological data. Called CAP (for Canonical Analysis of Principal Coordinates), the method can use any distance or dissimilarity measure, and uses canonical tests using permutations to address hypotheses concerning correlations or differences among groups. Using reef fish data from northern New Zealand, we show how it can uncover patterns that are masked in an unconstrained ordination (such multidimensional scaling). We suggest that a CAP ordination together with an unconstrained ordination provide important information with reference to explicit a priori hypotheses concerning multivariate data.
We describe a new method for constrained ordination (with reference to an a priori specified hypothesis) of multivariate ecological data. Called CAP (for Canonical Analysis of Principal Coordinates), the method can use any distance or dissimilarity measure, and uses canonical tests using permutations to address hypotheses concerning correlations or differences among groups. Using reef fish data from northern New Zealand, we show how it can uncover patterns that are masked in an unconstrained ordination (such multidimensional scaling). We suggest that a CAP ordination together with an unconstrained ordination provide important information with reference to explicit a priori hypotheses concerning multivariate data.
02 March, 2004
Standish et al. (2004): Invasion by a perennial herb increases decomposition rate and alters nutrient availability in warm temperate lowland forest.
Standish, R.J., Williams, P.A., Robertson, A.W., Scott, N.A. and Hedderley, D.I. 2004. Invasion by a perennial herb increases decomposition rate and alters nutrient availability in warm temperate lowland forest remnants. Biological Invasions 6: 71–82.
While the impacts of invasive weeds on community processes are well studied, comparitively little is known about the impacts of weeds on ecosystem processes. We determined the impact of Tradescantia fluminensis on litter decomposition and nutrient availability in a remnant of New Zealand lowland podocarp-broadleaf forest. We used multiple approaches to demonstrate that Tradescantia increases litter decomposition and alters nutrient availability, effects which could influence the long-term viability of a majority of podocarp-broadleaf forest remnants affected with Tradescantia in New Zealand.
While the impacts of invasive weeds on community processes are well studied, comparitively little is known about the impacts of weeds on ecosystem processes. We determined the impact of Tradescantia fluminensis on litter decomposition and nutrient availability in a remnant of New Zealand lowland podocarp-broadleaf forest. We used multiple approaches to demonstrate that Tradescantia increases litter decomposition and alters nutrient availability, effects which could influence the long-term viability of a majority of podocarp-broadleaf forest remnants affected with Tradescantia in New Zealand.
Standish (2004): Impact of an invasive clonal herb on epigaeic invertebrates in forest remnants in New Zealand.
Standish, R.J. 2004. Impact of an invasive clonal herb on epigaeic invertebrates in forest remnants in New Zealand. Biological Conservation 116: 49–58.
Tradescantia fluminensis is widespread throughout northern New Zealand and can become the dominant ground cover of forest remnants that it invades. Epigaeic invertebrates were sampled within three Tradescantia-infested plots and three non-infested plots at each of three sites using pitfall traps. Impacts of Tradescantia were apparent despite large differences in invertebrate assemblages among sites. The impact of Tradescantia could be a result of the weed’s tall, dense vegetation structure and associated microclimate, relative to native ground covers.
Tradescantia fluminensis is widespread throughout northern New Zealand and can become the dominant ground cover of forest remnants that it invades. Epigaeic invertebrates were sampled within three Tradescantia-infested plots and three non-infested plots at each of three sites using pitfall traps. Impacts of Tradescantia were apparent despite large differences in invertebrate assemblages among sites. The impact of Tradescantia could be a result of the weed’s tall, dense vegetation structure and associated microclimate, relative to native ground covers.
Moore and Battley (2003): Cockle-opening by a dabbling duck, the Brown Teal.
Moore, S.J. & Battley, P.F. 2003. Cockle-opening by a dabbling duck, the Brown Teal. Waterbirds 26: 331-334.
Many birds feed on bivalves, but only oystercatchers (Haematopus spp.) are known to prise open the shells. Brown Teal (Anas chlorotis), a dabbling duck endemic to New Zealand, were observed opening Common Cockles (Austrovenus stutchburyi) on Great Barrier Island. The teal jack-hammered into the open shells of feeding cockles and quickly scooped out the flesh. Despite having the bill morphology of a typical dabbling duck, they were adept at this feeding method.
Many birds feed on bivalves, but only oystercatchers (Haematopus spp.) are known to prise open the shells. Brown Teal (Anas chlorotis), a dabbling duck endemic to New Zealand, were observed opening Common Cockles (Austrovenus stutchburyi) on Great Barrier Island. The teal jack-hammered into the open shells of feeding cockles and quickly scooped out the flesh. Despite having the bill morphology of a typical dabbling duck, they were adept at this feeding method.
Gillman et al. (2003): Response of forest tree seedlings to simulated litterfall damage.
Gillman, L.N., Wright, S.D. & Ogden, J. 2003. Response of forest tree seedlings to simulated litterfall damage. Plant Ecology 169: 53-60.
Litterfall has been recognised as an important cause of seedling mortality in many forests. However, this is the first study to demonstrate differences in resilience to litterfall among seedling species. Seedling pairs of seven species were selected and one of each pair was pinned to the ground to simulate litterfall damage. Surprisingly, pinned Nothofagus menziesii and Hedycarya arborea suffered few mortalities and grew much faster than unpinned seedlings, whereas pinned Nestegis cunninghamii and Prumnopitys ferruginea suffered high mortalities and survivors grew little. Other species demonstrated intermediate resilience. This variable resilience combined with variability in microsite litterfall risk may contribute to regeneration niche differentiation.
Litterfall has been recognised as an important cause of seedling mortality in many forests. However, this is the first study to demonstrate differences in resilience to litterfall among seedling species. Seedling pairs of seven species were selected and one of each pair was pinned to the ground to simulate litterfall damage. Surprisingly, pinned Nothofagus menziesii and Hedycarya arborea suffered few mortalities and grew much faster than unpinned seedlings, whereas pinned Nestegis cunninghamii and Prumnopitys ferruginea suffered high mortalities and survivors grew little. Other species demonstrated intermediate resilience. This variable resilience combined with variability in microsite litterfall risk may contribute to regeneration niche differentiation.
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