Subtropical Eastern Australia Research Articles

Size distribution and new particle formation in subtropical eastern Australia

Environmental context. Atmospheric submicrometre particles have a significant impact on human health, visibility impairment, acid deposition and global climate. This study aims to understand the size distribution of submicrometre particles and new particle formation in eastern Australia and the results indicate that photochemical reactions of airborne pollutants are the main mechanism of new particle formation. The findings will contribute to a better understanding of the effects of aerosols on climate and the reduction of submicrometre particles in the atmosphere. Abstract. An intensive measurement campaign of particle concentrations, nitrogen oxides and meteorological parameters was conducted at a rural site in subtropical eastern Australia during September 2006. The aim of this work was to develop an understanding of the formation and growth processes of atmospheric aerosols, and the size distributions under various meteorological conditions. In order to achieve this, the origins of air arriving at the site were explored using back trajectories cluster analysis and the diurnal patterns of particle number concentration and size distribution for the classified air masses were investigated. The study showed that the photochemical formation of nucleation mode particles and their consequent growth was often observed. Furthermore, the nucleation mode usually dominated the size distribution and concentration of the photochemical event in the first 3–4 h with a geometric mean diameter of 26.9 nm and a geometric standard deviation of 1.28. The average particle growth rate was estimated to be 1.6 nm h–1, which is lower than that observed at urban sites, but comparable to the values reported in clean environments. The potential precursors of the photochemical events are also discussed.

Biogeography of seed‐dispersal syndromes, life‐forms and seed sizes among woody rain‐forest plants in Australia's subtropics

AbstractAim To enhance our understanding of the evolutionary interactions between seed‐dispersal syndromes, life‐forms, seed size, and habitat characteristics by studying their association with the regional‐scale distributions of subtropical rain‐forest plants in the context of climatic gradients.Location South‐east Queensland, subtropical eastern Australia (152° E, 26° S).Methods We classified 250 rain‐forest sites into six floristic site‐groups based on their woody plant composition. The resulting classification was strongly associated with variation in rainfall. The distribution of species across the floristic site‐groups was used to assign 568 species to seven habitat classes (one class for ‘widespread’ species, with all other species classified according to the site‐group within which they were most frequent). Species were also classified for three other categorical life‐history factors: three dispersal syndromes based on diaspore morphology (fleshy, wind‐assisted, and unadorned); four life‐forms (trees, shrubs and small trees, tall climbers, and short and shrubby climbers); and four seed‐diameter classes (< 3 mm, ≥ 3 and < 4.5 mm, ≥ 4.5 and < 7 mm, and ≥ 7 mm). We used a basic comparative approach augmented by simple phylogenetically constrained comparisons to assess association between dispersal syndrome, seed size, life‐form, and habitat class.Results Across the rain forests of south‐east Queensland, the proportion of species with fleshy diaspores or of large stature increases with rainfall. High‐rainfall sites also have larger average seed sizes, but the difference in average seed size between high‐ and low‐rainfall sites is small compared with variation within sites. Among species, those with fleshy fruit tend to have larger seeds and to favour high‐rainfall sites. Very few small trees produce diaspores adapted for wind‐assisted dispersal. On average, species with unadorned diaspores have smaller seeds than those with fleshy diaspores. However, within sites, species with unadorned and fleshy diaspores have similar average seed sizes, and some species with unadorned diaspores from high‐rainfall habitats have extremely large seeds.Main conclusions Commonly observed associations between fleshy fruit, larger plants, larger seeds, and productive habitats are apparent within the rain‐forest flora of south‐east Queensland. However, these associations are generally weak and involve complex interactions. For example, the strong tendency for species with fleshy fruit to have larger seeds than those with unadorned diaspores concealed a significant group of species from wetter forests that produce extremely large seeds and unadorned diaspores. The most widespread species in this study tend to be large plants (particularly robust lianes) and to produce fleshy fruit, but they tend not to have relatively large seeds. The association between large seeds, large plants, fleshy fruit and productive habitats is discussed as part of an evolutionary strategy favouring fitness in populations close to carrying capacity. We review some problems with focusing on establishment chances per seed as the driver towards association between large seeds, large plants and productive rain‐forest habitats (the difficult‐establishment hypothesis). Instead we suggest that production of large, short‐lived seeds by long‐lived plants in temporally stable, closed habitats may reflect the limited evolutionary potential for strategies enhancing colonization (e.g. producing large numbers of dormant seeds), thus allowing the establishment benefits of large seeds greater selective influence (the slow‐replacement hypothesis). The association of fleshy fruit with large seeds probably reflects the difficulty of dispersing large seeds by other means (the difficult‐dispersal hypothesis).

The impact of marine reserves on nekton diversity and community composition in subtropical eastern Australia

The effectiveness of marine reserve protection on the biodiversity of aquatic assemblages (i.e. nekton) in subtropical eastern Australia was examined within two small (<6 km 2) marine reserves and four non-reserve areas. The two marine reserves, and their corresponding non-reserves, were located in different geographical locations within Moreton Bay (north and south) and sites were surveyed with multiple hauls of a seine net. Species richness, evenness, density and mean size of the inshore communities were compared between the reserves and non-reserves. No statistical significant difference was detected in species richness between the areas however species evenness was significantly lower in the only non-reserve site impacted by commercial net fishing. Mean size of nekton was found to be significantly greater in the marine reserves compared to non-reserves but no statistical significant difference was found in the density of nekton between the study sites. Multivariate analysis revealed differences in community composition, particularly between the geographical locations where areas were impacted by different types of fishing pressure (recreational v commercial). These results highlight the impact commercial fishing can have on entire nekton assemblages, not just on targeted species. Our study demonstrates that the small marine reserves in Moreton Bay are protecting marine biodiversity and are thus at least partially achieving their management objective (to enhance the zone’s marine biodiversity).

Soil surface lichens on a 1500 kilometre climatic gradient in subtropical eastern Australia

Soil lichens are taxonomically diverse in subtropical eastern Australia. A total of 61 species in 25 genera is reported from a transect 1500 km long, running from the humid sub-tropical coast to the arid interior of the continent. The distribution of the lichen species and genera is associated with climatic pattern and with the growth form of the species. The total number of species found in bands of one degree of longitude along the transect decreases from the wet coastal region to the arid interior. Fruticose and foliose species dominated the flora in wetter regions and squamulose species in the dry interior.

Chloroplast DNA variation and population structure in the widespread forest tree, Eucalyptus grandis

Recognition of genetic structure of populations and the ability to identify vulnerable populations is useful for the formation of conservation management strategies for plants. Eucalyptus grandis is a tall forest tree that has a major area of occurrence in subtropical eastern Australia, with smaller populations located in the east coast tropics. Many widespread forest species exhibit population differentiation that corresponds to geographic regions. However, Eucalyptus grandis appears to be an exception based on isozyme and morphological data. This is intriguing given a large discontinuity between northern populations and those in the southern part of the species range. In this study, the distribution of a maternally inherited chloroplast locus was examined because it was more likely to reveal genetic structure due to the slower evolution of the chloroplast genome and limited dispersal of seed in eucalypts. As expected, the GST for chloroplast DNA was higher than that for nuclear DNA but indicated low population differentiation for a forest tree species. Phylogeographic analysis indicated that the 15 populations grouped into three broad geographical regions; however, overall population structure was weak suggesting that the large geographical disjunction in the distribution of E. grandis may be relatively recent. A paradigm for conservation management of E. grandis based on chloroplast DNA haplotype distribution would take into account the low differentiation among populations.

In vivo localization of manganese in the hyperaccumulator Gossia bidwillii (Benth.) N. Snow &amp; Guymer (Myrtaceae) by cryo‐SEM/EDAX

Gossia bidwillii (Myrtaceae) is a manganese (Mn)-hyperaccumulating tree native to subtropical eastern Australia. It typically contains foliar Mn levels in excess of 1% dry weight. However, in G. bidwillii and other Mn-hyperaccumulating species, the cellular and subcellular localization of Mn has not been measured. Quantitative in vivo cryo-scanning electron microscopy (SEM)/energy dispersive X-ray analysis (EDAX) was used to localize Mn and other elements in tissue collected from mature trees growing in a natural population. Cryo-SEM showed that the leaf mesophyll is differentiated as a double-layer palisade mesophyll above spongy mesophyll. Transmission electron microscopy (TEM) revealed that the palisade and epidermal cells are highly vacuolated. EDAX data were used to estimate in situ vacuolar Mn concentrations of all cell types in fresh cryo-fixed leaf tissues. The highest average vacuolar Mn concentration of over 500 mM was found in the upper-layer palisade mesophyll, while the lowest concentration of around 100 mM was found in the spongy mesophyll. Qualitative in vivo cryo-SEM/EDAX was employed to further investigate the spatial distribution of Mn in fresh leaf tissues and young bark tissue, which was also found to have a high Mn concentration. It is concluded that Mn distribution in G. bidwillii is quantitatively different to metal distribution in other hyperaccumulating species where the highest localized concentrations of these elements occur in non-photosynthmetic tissues such as epidermal cells and associated dermal structures including trichomes and leaf hairs.

Do frugivorous birds assist rainforest succession in weed dominated oldfield regrowth of subtropical Australia?

Exotic plants often form the first woody vegetation that grows on abandoned farmland. If this vegetation attracts vertebrate frugivores which disperse the seeds of native plants, then native plants may recruit to such oldfield sites. However, there is debate about the extent to which exotic vegetation assists or suppresses the regeneration of native plants, and about its effects on faunal biodiversity. These issues were investigated in subtropical eastern Australia, where rainforests were cleared for agriculture in the 19th century, and where regrowth dominated by camphor laurel ( Cinnamomum camphora, an exotic, fleshy-fruited tree) has become common on former agricultural land. The study assessed the assemblages of frugivorous birds, and the recruitment of rainforest plants, at 24 patches of camphor laurel regrowth. The patches were used by nearly all frugivorous birds associated with subtropical rainforest. Many of these birds (16 of 34 species) are considered to have a medium to high potential to disperse the seeds of rainforest plants, and eight of these were abundant and widespread in regrowth patches. Of 208 recorded plant species, 181 were native to local rainforest. The ratio of native to exotic species was higher amongst tree recruits than adult trees, both for numbers of species and individuals. Among native tree recruits, 79% of 75 species, and 93% of 1928 individuals, were potentially dispersed by birds. These recruits included many late-successional species, and there were relatively more individuals of late-successional, bird-dispersed native species amongst recruits than adult trees. The species richness, but not the abundance, of both frugivorous birds and of bird-dispersed rainforest trees decreased with distance from major rainforest remnants. Camphor laurel regrowth provides habitat for rainforest birds and creates conditions suitable for the regeneration of native rainforest plants on abandoned farmland. Careful management of regrowth dominated by fleshy-fruited exotic invasive trees can provide an opportunity for broadscale reforestation in extensively-cleared landscapes.

Impacts of tree invasion on floristic composition of subtropical grasslands on the Bunya Mountains, Australia

The effect of ongoing forest invasion on floristic composition of subtropical montane grasslands was considered by examining vascular plant species frequencies across 13 adjoining areas of grassland, invaded grassland (eucalypt forest &lt;50 years old) and eucalypt forest (&gt;50 years old) on the Bunya Mountains in subtropical eastern Australia. Tree invasion of grasslands over the last 50 years has had substantial facilitative or antagonistic net impacts on populations of many plant species. Increases in species frequency, indicating net facilitation, generally appear to occur earlier in forest development than do decreases in frequency, indicative of net antagonism. Although more than 20% of the flora showed substantial association with either grassland or forest, the dominant ground-stratum species in each habitat were quite similar and very few grassland species were not recorded in grassy forests. Forb species composition appears to change more rapidly after tree invasion than grass species composition. Relatively few forbs preferred forest to grassland, whereas shrubs, trees or lianes were substantially more frequent in forests. Replacement of grasslands by grassy forests would reduce landscape diversity and impact on other values in the Bunya Mountains. However, this study suggests that most, if not all, vascular plants that currently occur on the grasslands will persist in the area provided the grassy character of the eucalypt forests is maintained.

A Practical Tool to Identify Water Bodies with Potential for Mosquito Habitatunder Mangrove Canopy: Large-scale Airborne Scanning in the Thermal Band 8–13 μm

We address the practical issue of using thermal image data without adjustment or calibration for projects which do not require actual temperatures per se. Large scale airborne scanning in the thermal band at 8.5–13 μm was obtained for a mangrove and salt marsh in subtropical eastern Australia. For open sites, the raw image values were strongly positively correlated with ground level temperatures. For sites under mangrove canopy cover, image values indicated temperatures 2–4°C lower than those measured on the ground. The raw image was useful in identifying water bodies under canopy and has the potential for locating channel lines of deeper water. This could facilitate modification to increase flushing in the system, thereby reducing mosquito larval survival.

A revision of the Australian taxa previously attributed to Assiminea buccinoides (Quoy &amp; Gaimard) and Assiminea tasmanica Tenison-Woods (Mollusca:Gastropoda:Caenogastropoda:Assimineidae)

A new genus, Cryptassiminea, is introduced for the taxon previously known as Assiminea buccinoides (Quoy &amp; Gaimard). These small gastropods are abundant in mangrove and salt marsh habitats in south-eastern and subtropical eastern Australia. Seven species (five new) are recognised using morphological characters in the complex previously treated as a single species. Five taxa have rather narrow ranges while the other two are widespread and often sympatric. Two groups of species are recognised. One contains Cryptassiminea buccinoides, widespread in south-east and east Australia, and two closely related allopatric taxa from South Australia and south-eastern Tasmania (C. adelaidensis, sp. nov. and C. kershawi, sp. nov.). A second group of species is typified by Cryptassiminea tasmanica (Tenison-Woods), also widespread in east and south-east Australia and often sympatric with C. buccinoides. Allied to C. tasmanica, are two closely related taxa from western Victoria: C. glenelgensis, sp. nov. from the Glenelg River estuary and C. surryensis, sp. nov. from the Surry River estuary and Western Port, in the vicinity of Geelong. A distinctive species, Cryptassiminea insolata, sp. nov. from the east coast of Queensland, also has similarities with C. tasmanica. A cladistic analysis using morphological characters of the Cryptassiminea taxa and three other genera of Assimininae, with an omphalotropidine as the outgroup, resulted in a single tree. The new genus has rather poor support, possibly because many of its characters appear to be plesiomorphic within Assimineinae. Cryptassiminea is defined by a unique combination of characters but lacks any obvious synapomorphy. Two clades within Cryptassiminea are well supported, each containing the species-groups referred to above.

Abundance patterns across months and locations, and their differences between migrant and resident landbirds in lowland subtropical eucalypt forest

Many migrant landbird species are winter visitors to lowland eucalypt forests of the south-east Queensland region within subtropical eastern Australia. However, neither the specific patterns of habitat use by these migrant species, nor the extent to which the temporal and spatial patterns of migration are synchronised among different species, are well understood. This paper examines the pattern and synchrony of monthly change in bird species over a nine-month period (March-November), based on counts at seven survey sites within each of three large (>600 ha) lowland eucalypt forest remnants. These were surrounded by a mostly urban matrix, and widely separated within a total area of ∼ 1000 km2. Species were analysed with respect to both their individual abundances and collective patterns within four a priori groups: winter migrants, summer migrants, complex wanderers and residents/local movers. Collectively, the numbers of winter migrants were highest from May to August, but species’ broad arrival times varied from April to June, departures from July to October, and times of peak abundance also varied. Seven of eight winter migrant species that were individually analysed (Rose Robin, Yellow-faced and Scarlet Honeyeaters, Striated and Spotted Pardalotes, Grey Fantail and Golden Whistler, but not Rufous Whistler) showed large changes in abundance over the period. The abundance of these seven species did not vary among the three locations, and also showed concordant patterns of temporal change across locations. Some showed partial migration. The resident/local mover species showed little or no change in abundance over time, and eight of the 16 species analysed showed substantial abundance differences among locations. The difference in location effects between migrant and resident species may occur because the winter migrants are non-breeding visitors to the region, whilst the resident species are year-round inhabitants and are hence more selective since they are more likely to occupy long-term home ranges that must provide habitat suitable for nesting.

Two new species and two new records of aploactinid fishes (Pisces: Scorpaeniformes) from Australia

Two new species of aploactinids are described from coastal waters of subtropical eastern Australia. Pseudopataecus taenianotus, new genus and species, is described from seven specimens trawled inside the Capricorn-Bunker Group, Queensland. It is readily distinguished from other aploactinids by the markedly compressed head and body, large number of dorsal and anal-fin ray elements, frontal bone with laterally-bowed ridges forming a shallow fleshy depression, and distinctly anterior insertion of the first dorsal spine. Cocotropus microps, new species, is described from three specimens collected from inshore waters of southern Queensland and northern New South Wales. It has the lowest dorsal- and anal-fin ray counts of the genus, dorsal fin forming three elevated sections, and coloration including at least several small pale irregular spots or larger blotches. Two aploactinid species are recorded in Australian waters for the first time. Acanthosphex leurynnis Jordan & Seale, 1905, previously known from Hong Kong, Gulf of Thailand, southeast India, Indonesia and eastern Papua New Guinea, is reported from the Cumberland Group in tropical eastern Australia, Arafura Sea, Northern Territory, and near Perth, Western Australia. Xenaploactis cautes Poss & Eschmeyer, 1980, previously known only from the Andaman Sea and Gulf of Thailand, is reported from off Dampier, northwestern Australia and Gulf of Carpentaria, Queensland.

Microhabitat distribution of juvenile Penaeus merguiensis de Man and other epibenthic crustaceans within a mangrove forest in subtropical Australia

The distribution of juvenile Penaeus ( Fenneropenaeus) merguiensis de Man and other epibenthic crustaceans in different microhabitats within a riverine mangrove forest was examined in subtropical eastern Australia. Catches in vegetated and cleared microhabitats were compared at sites located in mangroves on the creek edge (1–2 m into the forest) and the inner forest (a further 14–22 m into the forest). Crustaceans were sampled using 3×3 m lift nets that were activated at the top of spring flood tides between March and May 2000. The abundance of P. merguiensis in the adjacent creek was also monitored during both high and low tides using a small beam trawl. A large size range of P. merguiensis was caught in the mangrove forest (2–13.5 mm carapace length) and the maximum density recorded was 1 prawn m −2. Catches of P. merguiensis were significantly higher at the creek edge than at the inner forest sites. Catches did not differ significantly between vegetated and cleared microhabitats, but catches were highly variable within microhabitats. This result was attributed to the very high activity levels of P. merguiensis and suggests that detecting differences between microhabitats used by prawns in the field would require a large number of samples. Substantial numbers of Acetes sibogae australis (Hansen), Macrobrachium novaehollandiae (de Man) and Metapenaeus bennettae (Racek and Dall) also entered the forest and catches of these species followed a similar pattern to those for P. merguiensis, i.e. catches were higher at the creek edge than the inner forest, did not differ between microhabitats and were highly variable within a microhabitat.

Hydrological characteristics of groundwater in a subtropical coastal plain with large variations in salinity: Pimpama, Queensland, Australia

The Pimpama coastal plain is situated in southern Moreton Bay, in subtropical eastern Australia. The plain is low lying and tidal and is situated behind a large sand barrier island. Largely due to recent (30 years) drainage networks within the flood plain, surface water quality has declined. Groundwater hydrographs have enabled the determination of different flow systems: a deeper system responding to seasonal weather patterns and a shallower flow system more responsive to individual rainfall events. Elevated potentiometric heads in semi-confined aquifers reflect upward movement of saline to hypersaline groundwaters. However, interaction of this deeper groundwater with shallower groundwater and the surface drains is yet to be determined. Recharge to the shallower system is by direct infiltration while recharge to the deeper system includes a component from landward ranges or bedrock outcrops within the plain. Discrimination between groundwater bodies is possible using salinity, ionic ratios and stable isotopes. Features of groundwater hydrology, the distribution of salinity and variations in water chemistry all suggest that under current conditions infiltration has increased, plus there is a greater landward migration of groundwaters of marine origin.

The Role of Non-Market Valuation in Forest Management and Recreation Policy

Forests, and particularly those where native and mixed species are grown, provide a variety of non-wood values, important among which are recreation and environmental services. Substantial progress has been made in recent years in estimating economic values on these services. A considerable amount of research on forest values has been carried out recently in tropical and sub-tropical eastern Australia, some of which is reported in the following papers. The need for estimates of non-wood forest benefits is apparent, and it is clear that further development of techniques and a greater understanding of the way these values can be integrated into public-sector decision making is required.

Seedling predation and growth at a rainforest–pasture ecotone, and the value of shoots as seedling analogues

Variation in the survival and growth of seedlings of six rainforest plant species was examined at a site where rainforest adjoins pasture in subtropical eastern Australia. The site was regularly used by a feeding group of red-necked pademelons Thylogale thetis, a herbivorous macropodid marsupial. Protection from herbivory, using wire mesh cages to exclude the pademelons, significantly increased seedling growth and survival in five of the six plant species. The caged minus uncaged seedling growth rates were used as a measure of the level of growth suppression due to pademelon herbivory, which varied significantly among plant species, was greater in pasture than in forest, and decreased with distance from the forest edge. This pattern of variation among species and positions was highly correlated with that observed in a separate series of experiments that had assessed overnight damage levels to cut shoots resulting from pademelon browsing. Cut shoots should therefore be useful as seedling analogues, offering a potential for better experimental replication than planted seedlings. Both data sets agree in their support of the proposition that pademelon predation on seedlings is likely to suppress differentially the regeneration of certain plant species at rainforest edges.

Subtropical drosophilids in Australia can be characterized by adult distribution across vegetation type and by height above forest floor

Understanding the pattern in which adult drosophilids of different species are distributed across and within different vegetation types is necessary for accurate interpretation of their local ecology and diversity. Such studies have been conducted mainly in temperate regions, and there is no basis for extrapolating their conclusions to tropical areas. This study describes the vertical distribution (0-20 m) of drosophilids attracted to banana baits in five different vegetation types in subtropical eastern Australia including open woodland, and rain-forest types. The distribution of most of the 15 common species could be characterized three-dimensionally by vegetation type and height above forest floor. Only one species, Scaptodrosophila lativittata, was common in all vegetation types and it was a canopy species in rain forests and a ground-level species in open woodland. Vertical distribution of some species clearly matched that of their larval hosts, but it did not in others. For example, the fungivore Leucophenga scutellata was mostly trapped well above the forest floor, yet it breeds at ground level, suggesting behavioural mode can influence vertical distributions. We conclude that the vertical dimension, although still poorly understood in relation to drosophilid habitats, needs to be taken into account when conducting and interpreting studies aimed at understanding drosophilid populations and communities in the subtropics.

Distribution, habitat requirements and conservation of the cascade treefrog ( Litoria pearsoniana, Anura: Hylidae)

Thirty-three species of Australian frogs have apparently declined in abundance since the late 1970s, some perhaps to extinction. The cascade treefrog Litoria pearsoniana, a stream-breeding frog from the forests of sub-tropical eastern Australia, was listed as an endangered species in Queensland following reports of population declines between 1978 and 1984. However, these reports were based on limited field data. I conducted a stratified survey across the geographic and environmental range of L. pearsoniana to determine its current distribution, abundance and habitat requirements. I detected L. pearsoniana in all major areas of mesic forest within its historical range, and at 29 of 65 sites surveyed. Statistical habitat modelling demonstrated that L. pearsoniana was most likely to occur at large streams with mesic midstorey vegetation, as indicated by the presence of palms. Abundance of the species, conditional on presence at a site, increased with increasing stream size. Litoria pearsoniana appears to have recovered from earlier population declines. However, suitability of habitat for the species in extensive areas of public forest may be threatened by cattle grazing, and the associated practices of tree clearing and frequent burning.

Do fragmented coastal heathlands have habitat value to birds in eastern Australia?

This study investigated the effects of habitat clearance and fragmentation on birds of coastal heathlands in subtropical eastern Australia. Abundance and species composition were compared among two types of cleared habitat (residential suburbs and sugar cane cropland) and four sizes of heathland remnant (1–2 ha, 5–10 ha, 20–50 ha and &gt;500 ha) in summer and winter. Cleared land contained a distinctly different bird species assemblage from heathland remnants. Residential sites contained a distinct suite of species consistent with that described for ‘open/developed land’ habitat elsewhere in the region. In contrast, cane cropland supported very few species. Heathland remnants &gt;500 ha contained high densities of ‘natural-vegetation-dependent’ species, whereas species of open/developed land were absent. Remnants of 1–2 ha had lowered densities of many natural-vegetation-dependent species, and a relatively high abundance of open/developed land species. Some of the avifaunal differences in the &gt;500-ha remnants and 5–50-ha range are probably due to confounding of remnant size with habitat, resulting from selective clearing of the landscape. Most of the heathland birds were intolerant of the matrix habitat (residential and cane cropland), but tolerant of decreased remnant area, down to a threshold of about 5 ha. However, the distinctive floristic associations of heathland vegetation are dependent on an environmental regime (low nutrient, low pH, fire, in some cases inundation) that is unlikely to persist in remnants tens of hectares in size, and longer-term declines in heathland birds, are predicted.

Mapping glider habitat in dry eucalypt forests for Montreal Process indicator 1.1e: Fragmentation of forest types

Summary Accurate habitat mapping is critical to landscape ecological studies such as required for developing and testing Montreal Process indicator 1.1e, fragmentation of forest types. This task poses a major challenge to remote sensing, especially in mixed—species, variable-age forests such as dry eucalypt forests of subtropical eastern Australia. In this paper, we apply an innovative approach that uses a small section of one-metre resolution airborne data to calibrate a moderate spatial resolution model (30 m resolution; scale 1:50 000) based on Landsat Thematic Mapper data to estimate canopy structural properties in St Marys State Forest, near Maryborough, south-eastern Queensland. The approach applies an image-processing model that assumes each image pixel is significantly larger than individual tree crowns and gaps to estimate crown-cover percentage, stem density and mean crown diameter. These parameters were classified into three discrete habitat classes to match the ecology of four exudivorous arboreal species (yellow—bellied glider Petaurus australis, sugar glider P. breviceps, squirrel glider P. norfolcensis, and feathertail glider Acrobates pygmaeus), and one folivorous arboreal marsupial, the greater glider Petauroides volons. These species were targeted due to the known ecological preference for old trees with hollows, and differences in their home range requirements. The overall mapping accuracy, visually assessed against transects (n = 93) interpreted from a digital orthophoto and validated in the field, was 79% (KHAT statistic = 0.72). The KHAT statistic serves as an indicator of the extent that the percentage correct values of the error matrix are due to ‘true’ agreement verses ‘chance’ agreement. This means that we are able to reliably report on the effect of habitat loss on target species, especially those with a large home range size (e.g. yellow-bellied glider). However, the classified habitat map failed to accurately capture the spatial patterning (e.g. patch size and shape) of stands with a trace or sub-dominance of senescent trees. This outcome makes the reporting of the effects of habitat fragmentation more problematic, especially for species with a small home range size (e.g. feathertail glider). With further model refinement and validation, however, this moderate-resolution approach offers an important, cost effective advancement in mapping the age of dry eucalypt forests in the region.