O’Donnell, C. F. J. 2001. Home range and use of space by Chalinolobus tuberculatus, a temperate rainforest bat from New Zealand. Journal of Zoology (London) 253: 253–264.
Home range sizes in long-tailed bats were among the largest published for Microchiroptera. These bats were highly mobile. One colony ranged over 100 km² and range size varied among age and sex classes (medians = 237–2,006 ha; max 5629 ha). A prediction that these bats have large ranges to minimise overlap between foraging bats, reflecting scarcity of food, requires testing. Large range size and the degree of individual spacing implies that conservation areas designed for bats should be large.
02 December, 2001
Kelly et al. (2001): Evaluating the wind-pollination benefits of mast seeding.
Kelly, D., Hart, D.E. & Allen, R.B. 2001. Evaluating the wind-pollination benefits of mast seeding. Ecology 82: 117-126.
A model for when plants gain pollination benefits from mast seeding shows that the greatest benefits go to species with low pollination success at the long term mean flowering effort. Tests of this model in Chionochloa, Nothofagus, Dacrydium and Betula alleghaniensis show a range of benefits from trivial in Chionochloa to very strong in N. solandri. This suggests that the pronounced masting seen in Nothofagus is attributable to pollination efficiencies. The model also explains the stronger masting seen at higher elevation sites, and predicts that habitat fragmentation could disrupt mast seeding benefits to pollination.
A model for when plants gain pollination benefits from mast seeding shows that the greatest benefits go to species with low pollination success at the long term mean flowering effort. Tests of this model in Chionochloa, Nothofagus, Dacrydium and Betula alleghaniensis show a range of benefits from trivial in Chionochloa to very strong in N. solandri. This suggests that the pronounced masting seen in Nothofagus is attributable to pollination efficiencies. The model also explains the stronger masting seen at higher elevation sites, and predicts that habitat fragmentation could disrupt mast seeding benefits to pollination.
Keedwell (2001): Evaluation of radio transmitters for measuring chick mortality in the banded dotterel.
Keedwell, R. 2001. Evaluation of radio transmitters for measuring chick mortality in the banded dotterel. Waterbirds 24: 217–223.
Details the results of a trial using elastic harnesses to attach radio transmitters to banded dotterel chicks in order to determine rates and causes of mortality. The technique only had limited application to young chicks because the harness occasionally fell off or entangled small chicks but the transmitters remained attached to chicks older than one week. Most mortality occurred in the first week, and predators were responsible for a minimum of 18% of deaths.
Details the results of a trial using elastic harnesses to attach radio transmitters to banded dotterel chicks in order to determine rates and causes of mortality. The technique only had limited application to young chicks because the harness occasionally fell off or entangled small chicks but the transmitters remained attached to chicks older than one week. Most mortality occurred in the first week, and predators were responsible for a minimum of 18% of deaths.
Wells et al. (2001): Forest dynamics in Westland, New Zealand: the importance of large, infrequent earthquake-induced disturbance.
Wells, A.; Duncan, R.P.; Stewart, G.H. 2001. Forest dynamics in Westland, New Zealand: the importance of large, infrequent earthquake-induced disturbance. Journal of Ecology 89: 1006-1018.
A reconstruction of forest disturbance history in a Westland catchment over the last 700 years reveals that, during this period, the catchment was affected by four massive episodes of landslipping and flooding, with up to 50% of the forested area of the catchment destroyed in a single episode. These episodes dominate the disturbance regime and were triggered by earthquakes, the three largest (dated c. 1460, 1620 and 1717 AD) caused by the last three major movements of the Alpine Fault. Much of the present forest structure in Westland reflects the impact of these major earthquakes.
A reconstruction of forest disturbance history in a Westland catchment over the last 700 years reveals that, during this period, the catchment was affected by four massive episodes of landslipping and flooding, with up to 50% of the forested area of the catchment destroyed in a single episode. These episodes dominate the disturbance regime and were triggered by earthquakes, the three largest (dated c. 1460, 1620 and 1717 AD) caused by the last three major movements of the Alpine Fault. Much of the present forest structure in Westland reflects the impact of these major earthquakes.
Wardle et al. (2001): Introduced browsing mammals in natural New Zealand forests: aboveground and belowground consequences.
Wardle, D. A.; Barker, G. M.; Yeates, G. W.; Bonner, K. I.; Ghani, A. 2001. Introduced browsing mammals in natural New Zealand forests: aboveground and belowground consequences. Ecological Monographs 71: 587–614.
The effects of browsing mammals (deer and goats) on plant and soil microbial and invertebrate communities was assessed for each of 30 long term exclosure plots in forests located throughout New Zealand. While browse layer vegetation density and diver-sity was consistently adversely affected by herbivores, the soil biota showed varied responses, and only invertebrates with larger body sizes were consistently adversely affected. There were also several instances in which browsers affected decomposer diversity, key soil processes and soil carbon and nitrogen sequestration. Frequently below-ground effects of these mammals were more severe than we would predict based on the response of vegetation.
The effects of browsing mammals (deer and goats) on plant and soil microbial and invertebrate communities was assessed for each of 30 long term exclosure plots in forests located throughout New Zealand. While browse layer vegetation density and diver-sity was consistently adversely affected by herbivores, the soil biota showed varied responses, and only invertebrates with larger body sizes were consistently adversely affected. There were also several instances in which browsers affected decomposer diversity, key soil processes and soil carbon and nitrogen sequestration. Frequently below-ground effects of these mammals were more severe than we would predict based on the response of vegetation.
Standish et al. (2001): The impact of an invasive weed Tradescantia fluminensis on native forest regeneration.
Standish, R.J.; Robertson, AW.; & Williams, P.A. 2001. The impact of an invasive weed Tradescantia fluminensis on native forest regeneration. Journal of Applied Ecology 38: 1253-1263.
A major effect of Tradescantia in forest is the suppression of seedlings. Data from two Manawatu/Horowhenua forest remnants showed that Tradescantia biomass reaches a maximum at edges and under canopy gaps. In these areas, Tradescantia biomass becomes so thick that very little light penetrates to the soil and almost all woody seedlings are suppressed. In shadier spots, the Tradescantia is not as thick, more light reaches the forest floor and more shade tolerant seedlings like kohekohe establish. These results suggest that imposing shade by establishing a subcanopy through planting may allow the natural regeneration cycle to be partly restored.
A major effect of Tradescantia in forest is the suppression of seedlings. Data from two Manawatu/Horowhenua forest remnants showed that Tradescantia biomass reaches a maximum at edges and under canopy gaps. In these areas, Tradescantia biomass becomes so thick that very little light penetrates to the soil and almost all woody seedlings are suppressed. In shadier spots, the Tradescantia is not as thick, more light reaches the forest floor and more shade tolerant seedlings like kohekohe establish. These results suggest that imposing shade by establishing a subcanopy through planting may allow the natural regeneration cycle to be partly restored.
Sinclair et al. (2001): Microhabitat selection and seasonality of alpine invertebrates.
Sinclair, B.J.; Lord, J.M.; Thompson, C.M. 2001. Microhabitat selection and seasonality of alpine invertebrates. Pedobiologia 45: 107-120.
This study examined the invertebrate fauna under rock slabs in summer and winter on Rock and Pillar Range, Otago. Rock size and season were the most important determinants of species presence. Species examined in detail were the cockroach Celatoblatta quinquemaculata, alpine weta Hemideina maori, and a spider Neoramia childi. We found evidence of positive interactions between weta and cockroach independent of rock size, but negative interactions between these species and spiders. The amount of vegetation around the rock was positively associated with cockroaches but negatively with weta. Adjacent vegetation composition had no effect.
This study examined the invertebrate fauna under rock slabs in summer and winter on Rock and Pillar Range, Otago. Rock size and season were the most important determinants of species presence. Species examined in detail were the cockroach Celatoblatta quinquemaculata, alpine weta Hemideina maori, and a spider Neoramia childi. We found evidence of positive interactions between weta and cockroach independent of rock size, but negative interactions between these species and spiders. The amount of vegetation around the rock was positively associated with cockroaches but negatively with weta. Adjacent vegetation composition had no effect.
Sinclair (2001): On the distribution of terrestrial invertebrates at Cape Bird, Ross Island, Antarctica.
Sinclair, B.J. 2001. On the distribution of terrestrial invertebrates at Cape Bird, Ross Island, Antarctica. Polar Biology 24: 394-400.
In this paper the terrestrial fauna of the Cape Bird Ice-Free Area is surveyed. Little relationship was found between the presence of macroscopic vegetation and invertebrates. This has important conservation implications, because many Antarctic protected areas are currently designated on the basis of vegetation, under the assumption that this preserves a representative terrestrial community, while this paper shows that this is not the case.
In this paper the terrestrial fauna of the Cape Bird Ice-Free Area is surveyed. Little relationship was found between the presence of macroscopic vegetation and invertebrates. This has important conservation implications, because many Antarctic protected areas are currently designated on the basis of vegetation, under the assumption that this preserves a representative terrestrial community, while this paper shows that this is not the case.
Sinclair (2001): Field ecology of freeze tolerance: the alpine cockroach Celatoblatta quinquemaculata.
Sinclair, B.J. 2001. Field ecology of freeze tolerance: interannual variation in cooling rates, freeze-thaw and thermal stress in the microhabitat of the alpine cockroach Celatoblatta quinquemaculata. Oikos 93: 286-293.
This paper takes laboratory data on the low temperature thermal biology of an alpine cockroach, and applies it to the interpretation of field microclimate data spanning 4 years. During the 1998 El Nino winter a lack of snow cover (and therefore insulation) resulted in much more extreme winter temperatures and many more freeze thaw events. This situation is used as an analogue for predicted climate change, and suggests that an alpine zone community may be maintained at low(ish) altitudes by severe frost events in this scenario.
This paper takes laboratory data on the low temperature thermal biology of an alpine cockroach, and applies it to the interpretation of field microclimate data spanning 4 years. During the 1998 El Nino winter a lack of snow cover (and therefore insulation) resulted in much more extreme winter temperatures and many more freeze thaw events. This situation is used as an analogue for predicted climate change, and suggests that an alpine zone community may be maintained at low(ish) altitudes by severe frost events in this scenario.
Sinclair (2001): Biologically relevant environmental data: Macros to make the most of microclimate recordings.
Sinclair, B.J. 2001. Biologically relevant environmental data: Macros to make the most of microclimate recordings. Cryo-Letters 22: 125-134.
Automated data loggers make it possible to gather vast quantities of environmental data, but the quantity can be overwhelming, limiting interpretation to means, rather than the biologically relevant thresholds. This paper presents macros for Microsoft Excel that calculate rates of change of a data series that has crossed a threshold; it will count the number of times a threshold is crossed (and allows for the decreasing threshold being different from the increasing threshold), and for calculating the amount of time that a threshold is exceeded. These macros are available electronically from the author bjs@sun.ac.za.
Automated data loggers make it possible to gather vast quantities of environmental data, but the quantity can be overwhelming, limiting interpretation to means, rather than the biologically relevant thresholds. This paper presents macros for Microsoft Excel that calculate rates of change of a data series that has crossed a threshold; it will count the number of times a threshold is crossed (and allows for the decreasing threshold being different from the increasing threshold), and for calculating the amount of time that a threshold is exceeded. These macros are available electronically from the author bjs@sun.ac.za.
Sessions and Kelly (2001): Heterogeneity in vertebrate and invertebrate herbivory and its consequences for New Zealand mistletoes.
Sessions, L.A. & Kelly, D. 2001. Heterogeneity in vertebrate and invertebrate herbivory and its consequences for New Zealand mistletoes. Austral Ecology 26: 571-581.
A major difference between vertebrate and invertebrate herbivores is that vertebrate damage is more unevenly distributed. Data on leaf losses by Peraxilla colensoi, P. tetrapetala and Alepis flavida at three sites show that the overall mean losses to possums and insects are similar, but possum damage is more patchy among branches within a plant, among plants, and among sites. This could mean that the unlucky plants attacked by vertebrate herbivores are more likely to die, whereas insects remove a constant small amount from all plants which may be less harmful. Possums also preferred Alepis to Peraxilla spp.
A major difference between vertebrate and invertebrate herbivores is that vertebrate damage is more unevenly distributed. Data on leaf losses by Peraxilla colensoi, P. tetrapetala and Alepis flavida at three sites show that the overall mean losses to possums and insects are similar, but possum damage is more patchy among branches within a plant, among plants, and among sites. This could mean that the unlucky plants attacked by vertebrate herbivores are more likely to die, whereas insects remove a constant small amount from all plants which may be less harmful. Possums also preferred Alepis to Peraxilla spp.
Sedgeley (2001): Winter activity in the tree-roosting lesser short-tailed bat, Mystacina tuberculata, in cold-temperate climate in New Zealand.
Sedgeley, J. A. 2001. Winter activity in the tree-roosting lesser short-tailed bat, Mystacina tuberculata, in cold-temperate climate in New Zealand. Acta Chiropterologica 3: 179–195
Unusually high levels of activity compared to other small bats in temperate forests were detected in the short-tailed bats during winter on Codfish Island. Radio-tagged bats flew on >50% of nights including those where minimum temperatures were 0 °C. Large levels of activity were recorded at roosts (max. = 1443 bats). Periods of activity were associated with feeding, social displays and changing roosts. Winter activity may not be as energetically expensive for short-tailed bats as other cold-temperate bat species. Their ability to forage on terrestrial invertebrates and to select different roost sites, allow them to be active more frequently and for longer.
Unusually high levels of activity compared to other small bats in temperate forests were detected in the short-tailed bats during winter on Codfish Island. Radio-tagged bats flew on >50% of nights including those where minimum temperatures were 0 °C. Large levels of activity were recorded at roosts (max. = 1443 bats). Periods of activity were associated with feeding, social displays and changing roosts. Winter activity may not be as energetically expensive for short-tailed bats as other cold-temperate bat species. Their ability to forage on terrestrial invertebrates and to select different roost sites, allow them to be active more frequently and for longer.
Sedgeley (2001): Quality of cavity micro-climate as a factor influencing maternity roost selection by a tree-dwelling bat.
Sedgeley, J. A. 2001. Quality of cavity micro-climate as a factor influencing maternity roost selection by a tree-dwelling bat, Chalinolobus tuberculatus, in New Zealand. Journal of Applied Ecology 38: 425–438.
Building on recent work that showed that long-tailed bats were highly selective of trees and cavities for roosting (Biological Conservation 88:261–276; J. Zoology London 249:437–446), this paper shows that these bats selected cavities on the basis of their thermoregulatory quality. Cavities used conveyed significant thermoregulatory advantages to roost occupants, especially reproductive females during the day and non-volant young, which were left alone for most of the night. Bat roosts had stable microclimates, displaying small ranges in temperature and hu-midity compared with external ambient conditions and available cavities that were not used by bats.
Building on recent work that showed that long-tailed bats were highly selective of trees and cavities for roosting (Biological Conservation 88:261–276; J. Zoology London 249:437–446), this paper shows that these bats selected cavities on the basis of their thermoregulatory quality. Cavities used conveyed significant thermoregulatory advantages to roost occupants, especially reproductive females during the day and non-volant young, which were left alone for most of the night. Bat roosts had stable microclimates, displaying small ranges in temperature and hu-midity compared with external ambient conditions and available cavities that were not used by bats.
Joy and Death (2001): Control of freshwater fish and crayfish community structure in Taranaki, New Zealand: dams, diadromy or habitat structure?
Joy M. K.; Death R. G. 2001. Control of freshwater fish and crayfish community structure in Taranaki, New Zealand: dams, diadromy or habitat structure? Freshwater Biology 46: 417-429.
This paper investigates the relationship between fish and crayfish communities and environmental variables at a number of scales from proximal to landscape on the Taranaki ring plain. The analysis showed elevation, distance from the coast and dams were the strongest predictors of fish and crayfish assemblages. Dams had greater impacts at lower elevation and landscape scale variables proved more important than proximal habitat variables in structuring fish communities.
This paper investigates the relationship between fish and crayfish communities and environmental variables at a number of scales from proximal to landscape on the Taranaki ring plain. The analysis showed elevation, distance from the coast and dams were the strongest predictors of fish and crayfish assemblages. Dams had greater impacts at lower elevation and landscape scale variables proved more important than proximal habitat variables in structuring fish communities.
Jeffries and Brunton (2001): Attracting endangered species to ‘safe’ habitats: responses to fairy terns of decoys.
Jeffries, D.S. & Brunton, D.H. 2001. Attracting endangered species to ‘safe’ habitats: responses to fairy terns of decoys. Animal Conservation 4: 301-305.
The New Zealand fairy tern is considered an endangered subspecies. The aims of this study were to quantify fairy tern responses to decoys and sound recordings and determine the viability of this technique for re-establishment of this species in protected habitat. Sixteen decoy trials were conducted at Papakanui Spit (36º06’ S, 174º36’ E). The decoy models were effective in attracting fairy terns to a specific area with >80% of landing episodes occurring in the decoy plots. The effectiveness of attracting terns to a specific site has potential as a safe and efficient means of trapping adults away from the nest.
The New Zealand fairy tern is considered an endangered subspecies. The aims of this study were to quantify fairy tern responses to decoys and sound recordings and determine the viability of this technique for re-establishment of this species in protected habitat. Sixteen decoy trials were conducted at Papakanui Spit (36º06’ S, 174º36’ E). The decoy models were effective in attracting fairy terns to a specific area with >80% of landing episodes occurring in the decoy plots. The effectiveness of attracting terns to a specific site has potential as a safe and efficient means of trapping adults away from the nest.
Lövei (2001): Extinctions, modern examples of.
Lövei, G.L. 2001. Extinctions, modern examples of. Pp. 731-743 in: Encyclopaedia of biodiversity, Vol. 2. Ed. by S. Levin. Academic Press, New York.
The fossil record indicates that recent extinctions were parallel with the arrival of modern humans to areas formerly uninhabited by them. These started at around 40,000 years before present. On continents, large mammals (>50 kg body mass), on islands, mostly birds were affected. The causes of these extinctions are not well known but include hunting, habitat alteration and the introduction of non-native species. By today this developed into a full-fledged mass extinction, affecting all species in all habitats, potentially surpassing the previous five mass extinction events in the history of Earth.
The fossil record indicates that recent extinctions were parallel with the arrival of modern humans to areas formerly uninhabited by them. These started at around 40,000 years before present. On continents, large mammals (>50 kg body mass), on islands, mostly birds were affected. The causes of these extinctions are not well known but include hunting, habitat alteration and the introduction of non-native species. By today this developed into a full-fledged mass extinction, affecting all species in all habitats, potentially surpassing the previous five mass extinction events in the history of Earth.
Lord et al. (2001): Effects of human approaches to nests of northern NZ dotterels.
Lord, A., Waas, J.R., Innes, J., & Whittingham, M.J. 2001. Effects of human approaches to nests of northern NZ dotterels. Biological Conservation 98: 233-240.
People and dogs disturbing nesting NZ dotterels potentially decrease their nesting success. Dotterels flushed at greater distances and for longer times when there was a dog with the person, while responses to people walking and running did not differ. The results suggest that disruption would be greatly reduced if dogs were banned within 100m of nesting dotterels. Human access should be prevented within a 50 m radius on busy beaches, and 70 m on remote beaches.
People and dogs disturbing nesting NZ dotterels potentially decrease their nesting success. Dotterels flushed at greater distances and for longer times when there was a dog with the person, while responses to people walking and running did not differ. The results suggest that disruption would be greatly reduced if dogs were banned within 100m of nesting dotterels. Human access should be prevented within a 50 m radius on busy beaches, and 70 m on remote beaches.
Leathwick and Austin (2001): Competitive interactions between tree species in New Zealandís old-growth indigenous forests.
Leathwick, J. R.; & Austin, M. P. 2001. Competitive interactions between tree species in New Zealandís old-growth indigenous forests. Ecology 82: 2560–2573.
This paper presents results of an analysis that uses the Nothofagus disjunctions as a natural removal ëexperimentí to quantify the effects of competition from these patchily distributed species on other widespread tree species. Relationships between species distributions and environment are first analysed using multiple regressions, and then the magnitude of competition effects are assessed by adding statistical terms describing Nothofagus abundance. Results indicate that many species are substantially reduced in abundance in the presence of Nothofagus. In addition, both the shape of species responses to annual temperature and their optima vary as Nothofagus abundance increases.
This paper presents results of an analysis that uses the Nothofagus disjunctions as a natural removal ëexperimentí to quantify the effects of competition from these patchily distributed species on other widespread tree species. Relationships between species distributions and environment are first analysed using multiple regressions, and then the magnitude of competition effects are assessed by adding statistical terms describing Nothofagus abundance. Results indicate that many species are substantially reduced in abundance in the presence of Nothofagus. In addition, both the shape of species responses to annual temperature and their optima vary as Nothofagus abundance increases.
Leathwick and Whitehead (2001): Soil and atmospheric water deficits and the distributions of New Zealandís indigenous tree species.
Leathwick, J. R., & Whitehead, D. 2001. Soil and atmospheric water deficits and the distributions of New Zealandís indigenous tree species. Functional Ecology 15: 233–242.
This paper explores relationships between native tree species distributions and climate, with a particular focus on water relations. Results highlight the likely role of fôhn winds that produce very high air saturation deficits in explaining the low abundance of many species east of New Zealandís main mountain ranges. They also suggest that reduced rainfall in dry years is more important in affecting species distributions than long-term average rainfall.
This paper explores relationships between native tree species distributions and climate, with a particular focus on water relations. Results highlight the likely role of fôhn winds that produce very high air saturation deficits in explaining the low abundance of many species east of New Zealandís main mountain ranges. They also suggest that reduced rainfall in dry years is more important in affecting species distributions than long-term average rainfall.
Young and Kearvell (2001): Distinguishing between sexes and species: bill size in orange-fronted and yellow-crowned parakeets.
Young, J.R.; Kearvell, J.C. 2001. Distinguishing between sexes and species: bill size in orange-fronted and yellow-crowned parakeets, Cyanoramphus auriceps. Emu 101:137-143, 2001.
Controversy surrounds the taxonomic status of the Orange-fronted Parakeet (previously known as Cyanoramphus malherbi), officially a colour morph of the more common Yellow-crowned Parakeet C. auriceps. We analyse bill length and bill width measurements from 60 museum specimens of Orange-fronted Parakeet and 44 museum specimens of Yellow-crowned Parakeet. Male Orange-fronted Parakeets have shorter bills than male Yellow-crowned Parakeets — the difference between sample means is 0.7–0.8 mm. Power calculations show that others have most likely not seen the difference as significant because of small sample sizes. Our analysis illustrates a useful statistical technique for identifying morphological differences between two species where both species are sexually dimorphic but the sex of each individual is uncertain.
Controversy surrounds the taxonomic status of the Orange-fronted Parakeet (previously known as Cyanoramphus malherbi), officially a colour morph of the more common Yellow-crowned Parakeet C. auriceps. We analyse bill length and bill width measurements from 60 museum specimens of Orange-fronted Parakeet and 44 museum specimens of Yellow-crowned Parakeet. Male Orange-fronted Parakeets have shorter bills than male Yellow-crowned Parakeets — the difference between sample means is 0.7–0.8 mm. Power calculations show that others have most likely not seen the difference as significant because of small sample sizes. Our analysis illustrates a useful statistical technique for identifying morphological differences between two species where both species are sexually dimorphic but the sex of each individual is uncertain.
Toft et al. (2001): Impacts of the weed Tradescantia fluminensis on insect communities in fragmented forests in New Zealand.
Toft, R. J.; Harris, R. J.; Williams, P. A. 2001. Impacts of the weed Tradescantia fluminensis on insect communities in fragmented forests in New Zealand. Biological Conservation 102: 31–46.
The impact of Tradescantia on insect communities, as represented by Malaise-trapped beetles and fungus gnats (Diptera: Mycetophilidae s. l.), was studied at three lowland forest fragments in the southern North Island. The proportion of Tradescantia cover within study plots was a poor predictor of species richness for either beetles or fungus gnats, but there was evidence that particular taxa were affected. The richness of beetle and fungus gnat species was correlated with vascular plant richness. As Tradescantia is known to prevent regeneration of many native plants, we predict a corresponding decline in invertebrate diversity and fragment complementarity where the weed is established.
The impact of Tradescantia on insect communities, as represented by Malaise-trapped beetles and fungus gnats (Diptera: Mycetophilidae s. l.), was studied at three lowland forest fragments in the southern North Island. The proportion of Tradescantia cover within study plots was a poor predictor of species richness for either beetles or fungus gnats, but there was evidence that particular taxa were affected. The richness of beetle and fungus gnat species was correlated with vascular plant richness. As Tradescantia is known to prevent regeneration of many native plants, we predict a corresponding decline in invertebrate diversity and fragment complementarity where the weed is established.
Holzapfel (2001): Studies of the New Zealand root-parasite Dactylanthus taylorii (Balanophoraceae).
Holzapfel, S. 2001. Studies of the New Zealand root-parasite Dactylanthus taylorii (Balanophoraceae). Englera 22: 1–176.
New research on flower anatomy, seed development, germination, vegetative reproduction, infection of host trees and genetic diversity of the endemic root-parasite Dactylanthus taylorii. A number of misinterpretations and generalisations in the literature about the family and the species itself are clarified. The anatomy of the female flower is described at various stages of development and the embryo of D. taylorii is described for the first time. Seeds are able to germinate without the presence of a host tree. RAPDs show genetic distinctness of even neighbour-ing populations and did not support the occurrence of monoecy in D. taylorii. Includes illustrations.
New research on flower anatomy, seed development, germination, vegetative reproduction, infection of host trees and genetic diversity of the endemic root-parasite Dactylanthus taylorii. A number of misinterpretations and generalisations in the literature about the family and the species itself are clarified. The anatomy of the female flower is described at various stages of development and the embryo of D. taylorii is described for the first time. Seeds are able to germinate without the presence of a host tree. RAPDs show genetic distinctness of even neighbour-ing populations and did not support the occurrence of monoecy in D. taylorii. Includes illustrations.
Beggs (2001): The ecological consequences of social wasps (Vespula spp.) invading an ecosystem that has an abundant carbohydrate resource.
Beggs, J.R. 2001. The ecological consequences of social wasps (Vespula spp.) invading an ecosystem that has an abundant carbohydrate resource. Biological Conservation 99: 17–28.
This paper reviews the impact that introduced social wasps are having in beech (Nothofagus spp) forest infested with endemic honeydew-producing scale insects. There is about 1 million ha of honeydew-infested beech forest in South Island, New Zealand. Wasps are abundant in these forests, and compete with native species for the honeydew resource. Additionally, wasps consume large quantities of native invertebrates. Wasp abundance needs to be reduced by 80-90% to conserve vulnerable invertebrate species. The paper also discusses how wasps could affect nutrient cycling, and the risk of an invasion by ants or other social wasps.
This paper reviews the impact that introduced social wasps are having in beech (Nothofagus spp) forest infested with endemic honeydew-producing scale insects. There is about 1 million ha of honeydew-infested beech forest in South Island, New Zealand. Wasps are abundant in these forests, and compete with native species for the honeydew resource. Additionally, wasps consume large quantities of native invertebrates. Wasp abundance needs to be reduced by 80-90% to conserve vulnerable invertebrate species. The paper also discusses how wasps could affect nutrient cycling, and the risk of an invasion by ants or other social wasps.
Cullen et al. (2001): Disturbance and climate warming influences on New Zealand Nothofagus treeline population dynamics.
Cullen, L.E.; Stewart, G.H.; Duncan, R.P.; Palmer, J.G. 2001. Disturbance and climate warming influences on New Zealand Nothofagus treeline population dynamics. Journal of Ecology 89: 1061-1071.
This paper uses forest stand history reconstruction to infer the relative roles of climate warming and disturbance on the population dynamics of silver beech dominated treelines in north Westland. Tree recruitment over the last 300 years has been episodic in response to small, localized disturbances, while climate warming over the last 50 years has had no influence on recruitment. Any influence of climate warming may be masked by the overwhelming importance of disturbance in driving treeline population dynamics in these forests.
This paper uses forest stand history reconstruction to infer the relative roles of climate warming and disturbance on the population dynamics of silver beech dominated treelines in north Westland. Tree recruitment over the last 300 years has been episodic in response to small, localized disturbances, while climate warming over the last 50 years has had no influence on recruitment. Any influence of climate warming may be masked by the overwhelming importance of disturbance in driving treeline population dynamics in these forests.
Flux (2001): Evidence of self-limitation in wild vertebrate populations.
Flux, J.E.C. 2001. Evidence of self-limitation in wild vertebrate populations. Oikos 92: 555-557.
Compared with other species of rabbits, hares, and pikas (Order Lagomorpha), European rabbits reach exceptionally high population densities and often starve. I suggest this maladaptation is a result of previous domestication, a process designed to break down natural social barriers by providing unlimited food and artificial crowding for many generations. This explains the propensity for domestic animals and human commensals to become serious pests. As a corollary it supports Wynne-Edwards' contention that wild animal populations are regulated by social behaviour at limits safely below their normal food supply, because the disruption of social behaviour leads to overpopulation.
Compared with other species of rabbits, hares, and pikas (Order Lagomorpha), European rabbits reach exceptionally high population densities and often starve. I suggest this maladaptation is a result of previous domestication, a process designed to break down natural social barriers by providing unlimited food and artificial crowding for many generations. This explains the propensity for domestic animals and human commensals to become serious pests. As a corollary it supports Wynne-Edwards' contention that wild animal populations are regulated by social behaviour at limits safely below their normal food supply, because the disruption of social behaviour leads to overpopulation.
Miller et al. (2001): Home range of stoats (Mustela erminea) in podocarp forest, south Westland, New Zealand.
Miller, C.; Elliot, M.; Alterio, N. 2001. Home range of stoats (Mustela erminea) in podocarp forest, south Westland, New Zealand: implications for a control strategy. Wildlife Research 28: 165-172.
Predation by stoats threatens the survival of Okarito brown kiwi (Apteryx australis). Home range data from stoats at Okarito forest are presented, and the implications of these for the development of a stoat control strategy are discussed.
Predation by stoats threatens the survival of Okarito brown kiwi (Apteryx australis). Home range data from stoats at Okarito forest are presented, and the implications of these for the development of a stoat control strategy are discussed.
McGlone et al. (2001): Endemism, species selection and the origin and distribution of the vascular plant flora of New Zealand.
McGlone, M.S.; Duncan, R.P.; Heenan, P.B. 2001. Endemism, species selection and the origin and distribution of the vascular plant flora of New Zealand. Journal of Biogeography 28: 199-216.
This paper evaluates competing views on the origin and distribution of New Zealand's vascular plant flora, concluding that ecological traits such as species dispersal capabilities and habitat requirements have played a key role in the formation of the flora and in shaping the geographic patterns of disjunction and endemism within New Zealand.
This paper evaluates competing views on the origin and distribution of New Zealand's vascular plant flora, concluding that ecological traits such as species dispersal capabilities and habitat requirements have played a key role in the formation of the flora and in shaping the geographic patterns of disjunction and endemism within New Zealand.
Gillman and Ogden (2001): Physical damage by litterfall to canopy tree seedlings in two temperate New Zealand forests.
Gillman, L.N.; Ogden, J. 2001. Physical damage by litterfall to canopy tree seedlings in two temperate New Zealand forests. Journal of Vegetation Science 12: 671-676.
Litterfall has been demonstrated to be an important cause of tree seedling damage and mortality in several tropical forests. This study demonstrates that it can also be very important in New Zealand temperate forest. Litterfall was the cause of a significant proportion of seedling mortality in kauri forest at Huapai (18%) and in podocarp/angiosperm forest at Pureora (11%). Annual damage to natural seedlings, and to artificial seedlings constructed from plastic straws and wire, were significantly greater at Huapai than at Pureora, and the damage rate to artificial seedlings at Huapai was similar to those recorded in tropical forests.
Litterfall has been demonstrated to be an important cause of tree seedling damage and mortality in several tropical forests. This study demonstrates that it can also be very important in New Zealand temperate forest. Litterfall was the cause of a significant proportion of seedling mortality in kauri forest at Huapai (18%) and in podocarp/angiosperm forest at Pureora (11%). Annual damage to natural seedlings, and to artificial seedlings constructed from plastic straws and wire, were significantly greater at Huapai than at Pureora, and the damage rate to artificial seedlings at Huapai was similar to those recorded in tropical forests.
Norbury (2001): Conserving dryland lizards by reducing predator-mediated apparent competition and direct competition with introduced rabbits.
Norbury, G. 2001. Conserving dryland lizards by reducing predator-mediated apparent competition and direct competition with introduced rabbits. Journal of Applied Ecology 38: 1350-1361.
This paper examines the potential for introduced rabbits to cause extinction of native secondary prey species (common skinks) in dry grasslands. Because rabbits are the preferred prey of introduced predators (ferret and cats), rabbit abundance dictates predator abundance and predators’ consumption of native skinks. More rabbits mean more predators, and sudden declines in rabbit abundance create acute peaks in consumption of skinks because predators switch their diet. Rabbits have further impacts because they consume the habitat of native skinks. When skink numbers reach critically low levels, predation can drive them locally extinct.
This paper examines the potential for introduced rabbits to cause extinction of native secondary prey species (common skinks) in dry grasslands. Because rabbits are the preferred prey of introduced predators (ferret and cats), rabbit abundance dictates predator abundance and predators’ consumption of native skinks. More rabbits mean more predators, and sudden declines in rabbit abundance create acute peaks in consumption of skinks because predators switch their diet. Rabbits have further impacts because they consume the habitat of native skinks. When skink numbers reach critically low levels, predation can drive them locally extinct.
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