ABSTRACT Simulated ecological data sets have been widely used to assess the ability of ordination... more ABSTRACT Simulated ecological data sets have been widely used to assess the ability of ordination techniques to portray patterns in ecological assemblage data. Such data sets typically contain a single assemblage sampled over an environmental gradient or set of gradients. Little has been done on the generation of artificial data sets that contain a number of different species assemblages, to aid in the evaluation of multivariate techniques that test for differences between assemblages of species. This paper describes and compares two simulation methods that generate ecologically realistic artificial multi-assemblage data sets. Both methods provide multivariate data (e.g. species abundances) for replicate sites within discretely different assemblages. The first technique is a coenocline model based on species responses to variation modeled by a five-parameter β-function, where variation in species abundances both within and between assemblages is governed by differences in the positions of sites and assemblages along environmental gradients. The second technique, the resampling method, involves bootstrap resampling of real assemblage data sets, with the addition of selected types of controlled differences between assemblages. Here we use it to generate turnover in species composition. We calibrate both simulation methods based on a field assemblage of bird species. The two different simulation methods portray different levels and types of between-assemblage variation. The resampling method allows greater control over some aspects of assemblage difference (e.g. independently varying differences in species richness and compositional turnover) than the coenocline method. Both can generate usable replicated simulated data sets for assessing the ability of multivariate tests to detect ecological variation among assemblages.
Under future climate drought-induced tree mortality may result in the contraction of species rang... more Under future climate drought-induced tree mortality may result in the contraction of species ranges and the reorganization of community composition where abundant and peripheral species exchange their patterns of dominance. Predicting these changes will be challenging because the future suitable habitat may be a mismatch for the current bioclimatic envelope because of discrepancies between the realized and fundamental niche. Here we evaluate the extent of the discrepancy, as applied to tree species in relation to their relative field-recorded drought sensitivities and their observed range-wide environmental moisture envelopes. The hypothesis tested was that different species levels of drought-induced damage at sites where they co-occur will be positively associated with the minimum moisture availability in the most drought-prone part of each species current geographic range. We tested the hypothesis using drought damage measurements for 13 Australian Myrtaceae (including Eucalyptus) tree species at a site where all co-occur, together with 120 years of climate data across their geographical ranges. With limited statistical power the results generated only modest support for the hypothesis suggesting limited capacity to predict future distributions under climate change scenarios. In spite of the poor dispersal capacities of Eucalyptus and allied genera, but consistent with knowledge of breeding systems and genetic variability within Eucalyptus, the findings also suggest that many species have a capacity for rapid adaptive response to climate change, including the vicissitudes of the late Quaternary.
ABSTRACT Observations on the use of native and exotic trees and shrubs by buds in winter were mad... more ABSTRACT Observations on the use of native and exotic trees and shrubs by buds in winter were made in the suburbs of Brisbane (1985, 1986) and Melbourne (1975). Among buds using woody plants for purposes other than foraging, native buds were consistently associated with native plants. In the Brisbane winter of 1985 there was no significant difference in the use of native and exotic plants by foraging native and exotic birds. However, in the drier winter of 1986 and in Melbourne, native buds foraged proportionately more frequently on native plants than did exotic buds and, when not foraging, used artiticial structures (as opposed to woody plants) less frequently. Exotic buds foraged proportionately more on the ground than on plants relative to the native buds in Melbourne and in the Brisbane winter of 1985. Counts of foliagk invertebrates were also made in winter in both cities. There were far more invertebrates on foliage in Brisbane than in Melbourne. Insect resting stages (egg masses and pupae), lerps and scales occurred more frequently on native than on exotic plants. Invertebrate densities on native plants exceeded those on exotics in Melbourne but not in Brisbane, due to the higher proportion of insect resting stages in Melbourne. The association between native birds and plants was weaker in Brisbane than in Melbourne and this is partially explicable by the differences in invertebrate numbers.
... Beetle species' responses suggest that microclimate mediates fragmentation effects in tr... more ... Beetle species' responses suggest that microclimate mediates fragmentation effects in tropical Australian rainforest. PETER S. GRIMBACHER,; CARLA P. CATTERALL,; ROGER L. KITCHING. ... 1998; Gascon et al. 1999; Davis 2000; Davies et al. 2001; Ricketts 2001). ...
Mulch is widely used to encourage establishment and growth of replanted vegetation in forest rest... more Mulch is widely used to encourage establishment and growth of replanted vegetation in forest restoration. The presence of mulch may also benefit soil and litter dwelling arthropods, but little is known about how recolonizing arthropods respond to different types and quantities of mulch used in forest restoration. We employed a manipulative field experiment to assess the effects of mulch type and depth on the colonization patterns of ants and other soil and litter arthropods in created habitat patches. Experimental habitat patches of 2.5 m x 2.5 m were established by adding sterilized hay (a conventionally used mulching material) or forest woodchip (a structurally more complex alternative) at two depths (shallow 3?5 cm, deep 10?15 cm) to create conditions similar to those during the initial stages of rainforest restoration. These were deployed at five sites adjacent to rainforest remnants on the Maleny plateau of subtropical eastern Australia. Despite its simple composition, hay performed better than woodchip in facilitating colonization by arthropods characteristic of rainforest. Shallow hay was favored by rainforest-dependent ant species. Although the results supported the use of hay over woodchip as habitat for rainforest arthropods, neither hay nor woodchip excluded arthropods characteristic of pasture.
... Arthropods were sampled from 24 sites (12 sites each in rainforest and pasture) using two met... more ... Arthropods were sampled from 24 sites (12 sites each in rainforest and pasture) using two methods (extrac-tion from litter, pitfall traps). ... and subsequent land use Akihiro Nakamura Æ Carla P. Catterall Æ Alan PN House Æ Roger L. Kitching Æ Chris J. Burwell ...
ABSTRACT Simulated ecological data sets have been widely used to assess the ability of ordination... more ABSTRACT Simulated ecological data sets have been widely used to assess the ability of ordination techniques to portray patterns in ecological assemblage data. Such data sets typically contain a single assemblage sampled over an environmental gradient or set of gradients. Little has been done on the generation of artificial data sets that contain a number of different species assemblages, to aid in the evaluation of multivariate techniques that test for differences between assemblages of species. This paper describes and compares two simulation methods that generate ecologically realistic artificial multi-assemblage data sets. Both methods provide multivariate data (e.g. species abundances) for replicate sites within discretely different assemblages. The first technique is a coenocline model based on species responses to variation modeled by a five-parameter β-function, where variation in species abundances both within and between assemblages is governed by differences in the positions of sites and assemblages along environmental gradients. The second technique, the resampling method, involves bootstrap resampling of real assemblage data sets, with the addition of selected types of controlled differences between assemblages. Here we use it to generate turnover in species composition. We calibrate both simulation methods based on a field assemblage of bird species. The two different simulation methods portray different levels and types of between-assemblage variation. The resampling method allows greater control over some aspects of assemblage difference (e.g. independently varying differences in species richness and compositional turnover) than the coenocline method. Both can generate usable replicated simulated data sets for assessing the ability of multivariate tests to detect ecological variation among assemblages.
Under future climate drought-induced tree mortality may result in the contraction of species rang... more Under future climate drought-induced tree mortality may result in the contraction of species ranges and the reorganization of community composition where abundant and peripheral species exchange their patterns of dominance. Predicting these changes will be challenging because the future suitable habitat may be a mismatch for the current bioclimatic envelope because of discrepancies between the realized and fundamental niche. Here we evaluate the extent of the discrepancy, as applied to tree species in relation to their relative field-recorded drought sensitivities and their observed range-wide environmental moisture envelopes. The hypothesis tested was that different species levels of drought-induced damage at sites where they co-occur will be positively associated with the minimum moisture availability in the most drought-prone part of each species current geographic range. We tested the hypothesis using drought damage measurements for 13 Australian Myrtaceae (including Eucalyptus) tree species at a site where all co-occur, together with 120 years of climate data across their geographical ranges. With limited statistical power the results generated only modest support for the hypothesis suggesting limited capacity to predict future distributions under climate change scenarios. In spite of the poor dispersal capacities of Eucalyptus and allied genera, but consistent with knowledge of breeding systems and genetic variability within Eucalyptus, the findings also suggest that many species have a capacity for rapid adaptive response to climate change, including the vicissitudes of the late Quaternary.
ABSTRACT Observations on the use of native and exotic trees and shrubs by buds in winter were mad... more ABSTRACT Observations on the use of native and exotic trees and shrubs by buds in winter were made in the suburbs of Brisbane (1985, 1986) and Melbourne (1975). Among buds using woody plants for purposes other than foraging, native buds were consistently associated with native plants. In the Brisbane winter of 1985 there was no significant difference in the use of native and exotic plants by foraging native and exotic birds. However, in the drier winter of 1986 and in Melbourne, native buds foraged proportionately more frequently on native plants than did exotic buds and, when not foraging, used artiticial structures (as opposed to woody plants) less frequently. Exotic buds foraged proportionately more on the ground than on plants relative to the native buds in Melbourne and in the Brisbane winter of 1985. Counts of foliagk invertebrates were also made in winter in both cities. There were far more invertebrates on foliage in Brisbane than in Melbourne. Insect resting stages (egg masses and pupae), lerps and scales occurred more frequently on native than on exotic plants. Invertebrate densities on native plants exceeded those on exotics in Melbourne but not in Brisbane, due to the higher proportion of insect resting stages in Melbourne. The association between native birds and plants was weaker in Brisbane than in Melbourne and this is partially explicable by the differences in invertebrate numbers.
... Beetle species' responses suggest that microclimate mediates fragmentation effects in tr... more ... Beetle species' responses suggest that microclimate mediates fragmentation effects in tropical Australian rainforest. PETER S. GRIMBACHER,; CARLA P. CATTERALL,; ROGER L. KITCHING. ... 1998; Gascon et al. 1999; Davis 2000; Davies et al. 2001; Ricketts 2001). ...
Mulch is widely used to encourage establishment and growth of replanted vegetation in forest rest... more Mulch is widely used to encourage establishment and growth of replanted vegetation in forest restoration. The presence of mulch may also benefit soil and litter dwelling arthropods, but little is known about how recolonizing arthropods respond to different types and quantities of mulch used in forest restoration. We employed a manipulative field experiment to assess the effects of mulch type and depth on the colonization patterns of ants and other soil and litter arthropods in created habitat patches. Experimental habitat patches of 2.5 m x 2.5 m were established by adding sterilized hay (a conventionally used mulching material) or forest woodchip (a structurally more complex alternative) at two depths (shallow 3?5 cm, deep 10?15 cm) to create conditions similar to those during the initial stages of rainforest restoration. These were deployed at five sites adjacent to rainforest remnants on the Maleny plateau of subtropical eastern Australia. Despite its simple composition, hay performed better than woodchip in facilitating colonization by arthropods characteristic of rainforest. Shallow hay was favored by rainforest-dependent ant species. Although the results supported the use of hay over woodchip as habitat for rainforest arthropods, neither hay nor woodchip excluded arthropods characteristic of pasture.
... Arthropods were sampled from 24 sites (12 sites each in rainforest and pasture) using two met... more ... Arthropods were sampled from 24 sites (12 sites each in rainforest and pasture) using two methods (extrac-tion from litter, pitfall traps). ... and subsequent land use Akihiro Nakamura Æ Carla P. Catterall Æ Alan PN House Æ Roger L. Kitching Æ Chris J. Burwell ...
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