Dry Rainforest Research Articles

Hydraulic architecture of deciduous and evergreen dry rainforest tree species from north-eastern Australia

Hydraulic conductivity and xylem anatomy were examined in stems of two evergreen species, Alphitonia excelsa (Fenzal) Benth. and Austromyrtus bidwillii (Benth.) Burret., and two drought-deciduous species, Brachychiton australis (Schott and Endl.) A. Terracc. and Cochlospermum gillivraei Benth., from a seasonally dry rainforest in north Queensland, Australia. The deciduous species possessed hydraulic architecture typical of drought-sensitive plants, i.e. low wood density, wider xylem vessels, higher maximal rates of sapwood specific hydraulic conductivity (Ks) and high vulnerability to drought-induced embolism. In contrast, the evergreen species had lower rates of Kh and leaf specific conductivity (KL) but were less susceptible to embolism. The evergreen species experienced leaf water potentials <−4.0 MPa during the dry season, while the deciduous species shed their leaves before leaf water potentials declined below −2.0 MPa. Thus, the hydraulic architecture of the evergreens allows them to withstand the greater xylem pressure gradients required to maintain water transport to the canopy during the dry season. Our results are consistent with observations made in neotropical dry forests and demonstrate that drought-deciduous species with low wood density and high water storage capacity are likely to be more hydraulically efficient, but more vulnerable to embolism, than coexisting evergreens.

Spatial pattern of dry rainforest colonizing unburnt Eucalyptus savanna

Abstract The spatial pattern of dry rainforest and savanna tree species was analysed in a 1.56‐ha plot within an unburnt eucalypt savanna woodland in north Queensland, Australia. Rainforest colonization constituted only 1.3% of the basal area and mostly consisted of individuals less than 3 m high. The distribution of rainforest trees was highly clumped around the large savanna eucalypt trees. Ecological mechanisms generating the clumped distribution are discussed in light of evidence from this study and the literature. Herbaceous biomass was not reduced under trees, suggesting that relief from grass competition has not favoured rainforest colonization under tree crowns. Edaphic facilitation through nutrient enrichment under savanna tree crowns appears to be only minor on the moderate fertility soils of the area. The highly clumped pattern of colonizing dry rainforest may be a consequence of seeds dropped from birds roosting in savanna trees.

Effects of fire and drought in a tropical eucalypt savanna colonized by rain forest

AbstractAimThis study documents the effects of multiple fires and drought on the woody structure of a north Australian savanna never grazed by domestic stock.LocationThe study was conducted in a 500 ha pocket ofEucalyptus‐dominated savanna surrounded by a late Quaternary lava flow. The flow is known as the Great Basalt Wall, locatedc.50 km northeast of Charters Towers in semi‐arid north‐eastern Australia. This region was exposed to the largest 5‐year rainfall deficit on record between 1992 and 1996.MethodsAll individual woody plants were tagged within a 1.56 ha plot. Species were segregated into their habitat affinities (rain forest, ecotone, savanna) and regeneration strategy (resprouter, seeder). The survivorship of plants within these categories was analysed in relation to fire intensity from the first fire, and to each of four fires lit between 1996 and 2001.ResultsBefore the first fire, the plot contained thirty‐one tree species including twenty‐one typical of the surrounding dry rain forest. These rain forest species were represented by small individuals and constituted &lt;1% of the total basal area of woody plants. The basal area of savanna trees was 7.5 m2 ha−1at the commencement of monitoring, although 31% had recently died and others had major crown damage. Further death of the drought debilitated savanna trees was substantial during the first year of monitoring and the basal area of live savanna trees declined to 1.1 m2 ha−1after 5 years. Most species from both rain forest and savanna were classified as resprouters and are capable of regenerating from underground organs after fire. Species without this ability (rain forest seeders and ecotone seeders) were mostly eliminated after the first two consecutive fires. Among resprouters, survivorship declined as fire intensity increased and this was more pronounced for rain forest than for savanna species. Repeated burning produced a cumulative effect of decreasing survivorship for rain forest resprouters relative to savanna resprouters.Main conclusionsThe study provides evidence that savanna and rain forest trees differ in fire susceptibility and that recurrent fire can explain the restricted distribution of rain forest in the seasonally arid Australian tropics. The time of death of the savanna trees is consistent with the regional pattern after severe drought, and highlights the importance of medium term climate cycles for the population dynamics of savanna tree species and structure of Australian savannas.

Historical changes in the bird fauna at Coomooboolaroo, northeastern Australia, from the early years of pastoral settlement (1873) to 1999

Across most of northern Australia, the historical record is generally insufficient to serve as a baseline for interpreting the impacts of European settlement on fauna. A notable exception is the pastoral property Coomoobolaroo (454 km 2) in central Queensland, where the ornithologist Charles Barnard maintained a detailed record of bird fauna from 1873 to 1933. We re-surveyed the property in 1999, and collated other information on its current avifauna, giving 242 species in total recorded over the period 1873–1999 (of which we had sufficient information to ascribe trends to 200 species). The bird fauna of Coomooboolaroo has undergone substantial change, across both of the periods 1873–1933 and 1934–1999. From 1873 to 1999, 45% of species declined or were lost from the property, compared with 13% of species that either colonised the property or increased. Most of the latter are widespread species or those known to benefit from clearing and land development. This extent of change appears at least as high as that reported for most comparable studies elsewhere in Australia, despite these being conducted at sites that have been subjected to superficially greater environmental degradation. The greatest rates of loss occurred among birds associated with softwood scrub (dry rainforest), grasslands and swamps. Smaller species were more susceptible to decline, but change in status was not significantly associated with foraging style nor different between residents and migrants. Many of the species that have declined at Coomooboolaroo have also declined in many other geographic regions, habitats and land-uses. Change in status at this property can be attributed to diverse factors, including changes in predation pressures; environmental change due to altered fire regimes and/or grazing by livestock; and vegetation clearance at both property and regional scales. The multiplicity and complex interrelationships of such factors renders it difficult to predict assemblage-level change.

Pit membrane porosity and water stress-induced cavitation in four co-existing dry rainforest tree species.

Aspects of xylem anatomy and vulnerability to water stress-induced embolism were examined in stems of two drought-deciduous species, Brachychiton australis (Schott and Endl.) A. Terracc. and Cochlospermum gillivraei Benth., and two evergreen species, Alphitonia excelsa (Fenzal) Benth. and Austromyrtus bidwillii (Benth.) Burret., growing in a seasonally dry rainforest. The deciduous species were more vulnerable to water stress-induced xylem embolism. B. australis and C. gillivraei reached a 50% loss of hydraulic conductivity at -3.17 MPa and -1.44 MPa, respectively; a 50% loss of hydraulic conductivity occurred at -5.56 MPa in A. excelsa and -5.12 MPa in A. bidwillii. To determine whether pit membrane porosity was responsible for greater vulnerability to embolism (air seeding hypothesis), pit membrane structure was examined. Expected pore sizes were calculated from vulnerability curves; however, the predicted inter-specific variation in pore sizes was not detected using scanning electron microscopy (pores were not visible to a resolution of 20 nm). Suspensions of colloidal gold particles were then perfused through branch sections. These experiments indicated that pit membrane pores were between 5 and 20 nm in diameter in all four species. The results may be explained by three possibilities: (a) the pores of the expected size range were not present, (b) larger pores, within the size range to cause air seeding, were present but were rare enough to avoid detection, or (c) pore sizes in the expected range only develop while the membrane is under mechanical stress (during air seeding) due to stretching/flexing.

A new species of Phyllurus (Lacertilia : Gekkonidae) and a revised phylogeny and key for the Australian leaf-tailed geckos

Phyllurus gulbaru, sp. nov., is a highly distinct species of leaf-tailed gecko restricted to rocky rainforest of Pattersons Gorge, north-west of Townsville. The possession of a cylindrical, non-depressed, tapering original and regenerated tail separates P. gulbaru from all congeners except P. caudiannulatus. From this species P. gulbaru is separated by having a partially divided, as opposed to fully divided, rostral scale. Furthermore, the very small spinose body tubercles of P. gulbaru are in marked contrast to the large spinose body scales of P. caudiannulatus. An analysis of 729 bp of mitochondrial 12S rRNA and cytochrome b genes reveals P. gulbaru to be a deeply divergent lineage with closer affinities to mid-east Queensland congeners than the geographically neighbouring P. amnicola on Mt Elliot. In conservation terms, P. gulbaru is clearly at risk. Field surveys of Pattersons Gorge and the adjacent ranges indicate that this species is restricted to a very small area of highly fragmented habitat, of which only a small proportion receives a degree of protection in State forest. Further, there is ongoing, unchecked destruction of dry rainforest habitat by fire. Under current IUCN criteria, P. gulbaru warrants an Endangered (B1, 2) listing.

Evolution and Biogeography of Alectryon (Sapindaceae)

Phylogenetic analysis of nucleotide sequences from four plastid loci (matK, partial trnK–matK introns, rps16 intron) and one nuclear locus (the internal transcribed spacer of rDNA; ITS-1) was conducted for 14 species of Alectryon and five related genera in Sapindaceae. Both matK and rps16 intron provide few informative characters within Alectryon, whereas ITS-1 provides the largest number of parsimony-informative characters and has the greatest sequence divergence between taxa. Support for branches in cladograms produced in PAUP increased markedly upon inclusion of ITS-1 data to matK and rps16 intron data. Analyses of each region alone or combined produced congruent results, suggesting that the regions are complementary. Phylogenetic analysis indicates that there are two main lineages within Alectryon, with A. subcinereus sister to the remaining sampled Alectryon taxa. Two morphological characters, presence/absence of petals and aril patterning, are congruent with the molecular phylogeny. One robustly supported clade is characterized by smooth arils and petals, in contrast to the taxa in the other major clade which have patterned arils and an absence of petals. These analyses also support a number of revised subgeneric groupings for Alectryon. The decision to submerge Heterodendrum in Alectryon is supported, although taxa belonging to Heterodendrum do not form a clade. The majority of the Australian Alectryon appear to belong to the tropical monsoonal/arid flora with species from both lineages being found in representative vine thickets across northern Australia. It appears that the seasonally dry rainforest communities comprise a number of elements that do not share common evolutionary histories within this genus.

Floral biology of dry rainforest in north Queensland and a comparison with adjacent savanna woodland

In north Queensland, Australia, dry rainforest (deciduous and semi-evergreen vine thicket) occurs as patches within a matrix of savanna woodland. With floral morphology and pollen–ovule ratios as indicators of pollination syndrome and breeding system, the floral biology of dry rainforest was compared with that of adjacent savanna woodland and with rainforest elsewhere. Contingency tables and analysis of variance were used to examine and compare breeding system, flower diameter, floral display and putative pollination syndrome for 156 dry rainforest and 33 savanna woodland taxa. Most (91 of 97) dry rainforest species had pollen–ovule ratios indicating obligate outbreeding. Similar levels of dioecy (21%) and patterns of flowering phenology were observed to those reported for rainforests elsewhere. For dry rainforest canopy trees, flower diameter and morphology indicated pollination by small, generalist insects. Canopy trees tended to flower in the wet season and have low ovule numbers. Taxa assigned to the wind-pollination syndrome had the highest pollen–ovule ratios, suggesting less efficient pollen transfer. Sclerophyll savanna taxa (and some emergent dry rainforest trees) tended to flower in the dry season, have large flowers, high ovule numbers and a high level of floral display.

Strangler Figs in a Stand of Dry Rainforest in the Lower Hunter Valley, NSW

A complete census was conducted of all hemi-epiphytic Ficus individuals within a single stand of dry rainforest. Substrate analyses were conducted on the material from potential hemi-epiphyte germination sites in an attempt to understand the factors influencing the distribution of hemi-epiphytic Ficus individuals within the stand. In all, 191 individuals of Ficus macrophylla ssp. macrophylla (Moreton Bay fig) and 65 individuals of Ficus superba var. henneana (deciduous fig) were found within the stand, providing a mean hemi-epiphyte density of 13.5/ha. Clear host preferences were shown for both fig species with two species, Olea paniculata (native olive) and Drypetes deplanchei (yellow tulip), shown to host 60 per cent and 21 per cent, respectively, of all hemi-epiphytes within the stand. These host trees are characterised by humus pockets that accumulate in depressions on their branches and trunk, as well as in branch axils. Their host potential is thought to be enhanced by the increased visitation of birds that feed on the fruit from both the hemi-epiphytes and these potential host trees. Substrate analyses revealed that while the highly organic epiphytic and rock-surface substrates had a high field capacity, their moisture holding capacity was low. The ponding of water and the reduced desiccation afforded by the microtopography of the germination sites ensures that these sites are more likely to maintain a viable moisture content. It appears that desiccation of the germination substrate could be the major cause of the high rate of juvenile hemi-epiphytic Ficus mortality.

Neogene and Quaternary history of vegetation, climate, and plant diversity in Amazonia

The neotropical Amazonian and Andean plant diversity developed mainly during the Tertiary. In Amazonia, Miocene floral diversity seems considerably higher than today. During the Neogene, tropical taxa entered newly created montane area, and montane taxa entered the tropical lowlands. The general decrease of temperature during the upper Neogene and especially during the Quaternary glacial periods may have caused considerable extinctions in the lowlands. Representation of pollen of apparently principally montane taxa ( Podocarpus, Hedyosmum) in Miocene, Pliocene, and Quaternary sediments of Amazonia and surroundings, is still difficult to interpret in terms of temperature decrease at low elevation. Changes in precipitation may have profound impact on the composition of vegetation communities; Ilex and Melastomataceae increase significantly in many glacial pollen records. Increase of Weinmannia in Amazonian pollen records seems the best indicator of downward migration of montane vegetation belts. A temperature lowering at sea-level of 4.5 ±1°C during the Last Glacial Maximum (LGM) seems reasonable; it may have caused a downslope migration of some 700 m of the lower montane vegetation belt; lower montane arboreal species may have been able to grow in higher elevation areas (>500 m) of Amazonia, increasing background pollen values of montane taxa in the area. Difference between a cool and wet Middle Pleniglacial (60–28 ka BP), and a cold and dry Upper Pleniglacial (28–14 ka BP; thus including the LGM) is evident in Andean and Amazonian records; statements about environmental conditions of the ice-age Amazon should be specified chronologically. The Middle Pleniglacial is a time of accumulation of fluvial sediments. The Upper Pleniglacial is a time of incision of the rivers in their sediments; sedimentation started again in the Lateglacial (since ca. 13 ka BP) and the Holocene, when lake levels rose again. Based on simplified considerations of precipitation changes and evaporation we estimate that LGM rainfall may have been reduced by values of ca. 45(±10%); Amazonian and Cordilleran lakes dried up; dry rain forest was locally replaced by savanna, savanna forest, or cerrado-type vegetation; dry rain forest, savanna forest, and pure savanna was locally replaced by extensive semi-desert dune formations (lower Rio Branco area in present-day central Amazonia). The present-day centers of higher rainfall (>2500 mm) surrounded by areas of lower rainfall, are refuge areas of the very wet rain forest and of the very high plant diversity (300 plant species per 0.1 ha), and they should have been that equally, or more, during the dry climate intervals (plant diversity of drier forests is in the order of 100–150 species per 0.1 ha). Both extinction and speciation in isolation under precipitation and temperature stress may have taken place in these refugia.

Experimental evidence on the importance of disturbance intensity for invasion of Lantana camara L. in dry rainforest–open forest ecotones in north-eastern NSW, Australia

The invasion of Lantana camara (a thicket-forming, woody weed) into dry rainforest–open forest ecotones was evaluated over a range of disturbance intensities associated with fire and livestock grazing. Three manipulation experiments were established in which wildfire (unburnt, low, and high intensity), overstorey damage (different levels of biomass removal), and nutrient addition (NPK) were used as disturbance categories in pair-wise factorial combinations across the chosen disturbance intensity range. The availability of key resources to the invading species resulting from disturbances was also measured over the established environmental gradients of light and soil fertility. Seedling establishment occurred in control treatments but growth was weak (averaging 0.85 g plant −1 year −1) and they failed to flower during the 27 months experimental period. High levels of nutrient addition (60–80 g m −2) without other forms of disturbance significantly increased growth (to 0.95 g plant −1 year −1) and germination (41.6–44.5%), while survival increased modestly (14.1–15.9 plants plot −1). Biomass increased significantly to 1.78 g plant −1 year −1 when the shrub layer was removed or burnt by a low intensity wildfire while germination and survival increased by 13.5 and 22.0% respectively over the control. Invasion increased further when the overstorey was physically removed or burnt with a high intensity wildfire as biomass increased significantly to 2.42 g plant −1 year −1, while germination and survival significantly increased by a further 35.6% and 40.7% respectively over the low intensity wildfire and shrub removal. Invasion was positively increased with disturbance intensity and increased resource availability. Light at ground level increased from 21.3 to 30.5% of ambient light when the shrub layer was damaged while it increased to 84.3% when the overstorey was damaged. A pattern of increasing plant performance with increasing intensity and number of combined disturbances was evident, although nutrient addition alone had little or no effect on plant performance, including flowering. The impact of low intensity fire on L. camara invasion was primarily produced by a response to increased light rather than increased nutrient availability while high intensity wildfire produced a secondary but minor response to increased soil fertility. Management of disturbances is critical for the long-term viability of dry rainforests and their ecotones. Shading by intact canopies is an effective barrier against successful invasion by L. camara and is the most appropriate strategy for managing invasion. This strategy will also contribute to the maintenance of conservation values and provide opportunities for dry rainforest development and expansion.

Lantana camara L. invasions in dry rainforest ‐ open forest ecotones: The role of disturbances associated with fire and cattle grazing

Abstract A field experiment was used to evaluate the effects of fire and cattle grazing on the initiation of Lantana camara invasions in dry rainforest‐open forest ecotones in the gorges of the Macleay River, NSW. A factorial combination of four factors (burning, biomass removal, soil scarification, and fertilization) at two levels (presence and absence) was established to assess the suitability of disturbed patches for germination, survival, and growth in association with changes in microclimate and resource availability. Burning, biomass removal and soil scarification, either singularly or in any combination, significantly increased germination, on average, by 19%, from 50.2% to 59.7%. Survival increased on average 26% across all treatments while mortality decreased by 26% when compared with the control. The differences between treatment combinations were not significant. Seedling growth was significantly enhanced by all disturbances, except by soil scarification alone. Treatment combinations that reduced vegetation cover (burning and/or biomass removal) and, therefore reduced shading, significantly increased L. camara biomass production by an average of 140% for all treatments. The control yielded 14.0 g m−2, while fertilizer alone and biomass removal alone yielded 27.6 g m−2 and 40.5 g m−2, respectively. Other treatment combinations averaged 35.2 g m−2 and were not significantly different from each other. Consequently, successful invasions are likely to occur whenever canopy disturbances create patches of greatly decreased competition and/or increased resource availability. Shading plays a greater role as a limiting factor than any other, while surface soil macronutrient levels are also important, particularly when combined with canopy disturbances that increase light availability. The effects of biomass reduction and soil disturbance associated with fire and cattle grazing are significant in the successful invasion of L. camara. Management strategies to reduce weed encroachment and community degradation must identify and maintain ecological barriers to L. camara invasion in order to promote rainforest conservation and biodiversity.

Broad Landscape Relations of the Moss Flora from Inland Dry Rainforest in North Queensland, Australia

The moss flora of dry rainforest in north Queensland was surveyed in conjunction with a vascular plant survey. Moss species richness was strongly correlated with patch area mean annual rainfall, and vascular plant species richness. Moss species richness rises where volcanic craters within the study area increase moisture status. Geological substrate had a stronger relationship with associations within the mass flora as defined by the TWINSPAN classificatory procedure and with individual moss species than either landform category or classificatory groups of vascular plants. The association of four species with large closed canopy patches may reflect a humid microclimate and suggests that all else being equal large patches will preserve more species than many small areas of rainforest. However, a high proportion of rare species were associated with the soil surface and there was no obvious way of predicting their locality.

Allelopathy as a competitive strategy in persistent thickets of Lantana camara L. in three Australian forest communities

Field experiments were established to assess possible allelopathic suppression by Lantana camara L. of two indigenous tree species. The design allowed comparison of allelopathic effects with density-dependent resource competition effects. Fire and its role in competitive interactions was included as an experimental treatment. Allelopathic responses were measured in L. camara thickets by germinating and growing Alectryon subcinereus (A. Gray) Radlk. in dry rainforest ecotones (Macleay River) or Cryptocarya rigida (Meissner) in warm temperate rainforest and wet sclerophyll forest (Lake Macquarie) at 10, 20 and 30 seedlings m-2, where L. camara was either physically removed (LR), burnt (LB), or cut and left in place (LT). Germination for both species increased significantly by completely removing L. camara (LR) whereas burning (LB) was significant only for C. rigida. Seedling growth for both species was negatively related to increasing density when all L. camara was removed (LR) but was positively related in the other two treatments (LB and LT). C. rigida seedling biomass increased 47.4% (1.75%2.58 g) and 68.6% (1.98%2.95 g) with increasing seedling density for LT and LB respectively and decreased 23.2% (2.93–2.25 g) for LR. A. subcinereus seedling biomass increased 29.7% (1.95–2.53 g) and 34.7% (2.25–3.03 g) with increasing seedling density for LT and LB respectively and decreased 27.9% (3.30–2.38 g) for LR. Phytotoxin dilution effects were inferred in LT and LB rather than density-dependent intraspecific competition, whereas the reverse was true for LR. Seedling biomass for C. rigida resulting from potential phytotoxin dilution at high seedling density was not significantly different from the response of LR at low seedling density but, for A. subcinereus, the phytotoxin dilution response was significantly less than LR at low seedling density. Moderately intense fire (LB) was not significantly different from the LT treatment at both locations, emphasising that moderate to low intensity fires should not be used to control existing invasions of L. camara. Competitive strategies for invasive populations are identified that may modify succession following disturbance, thereby allowing thicket formation and long-term persistence to affect community dynamics. Such strategies need to be recognised in managing natural communities, particularly for biodiversity conservation. Nomenclature: Harden (1990).

Broad Landscape Relations of the Moss Flora from Inland Dry Rainforest in North Queensland, Australia

Broad Landscape Relations of the Moss Flora from Inland Dry Rainforest in North Queensland, Australia

Rethinking the prehistory of hunter-gatherers, fire and vegetation change in northern Australia

Different types of evidence - palaeoecological, biogeographic and ethnographic - currently provide different perspectives on the question of hunter-gatherer impacts on fire-sensitive components of northern Australian vegetation. Here I analyze the apparent discrepancies, using evidence primarily from the Holocene. Using this more substantial body of evidence than is available for earlier periods, we can attempt to do justice to both ecological and social complexity. While dry rainforest patches and wet rainforest massifs need to be considered separately, each experienced more human alteration in the late Holocene than the early to mid-Holocene. In the former case, hunter-gatherer burning protected dry rainforest from climatically induced changes in fire regime; in the latter, it contributed to disturbance. Implications for future research into hunter-gatherer relations to land are discussed. This analysis does not preclude the possibility of analogous changes having occurred during the Pleistocene.

Land clearance and conservation of inland dry rainforest in north Queensland, Australia

About 28·2% of the area of inland dry rainforest patches has been cleared between latitudes 17°S and 23°26·5′S in north Queensland. Most of the clearance has occurred in the southern half of this study area. A greater proportion of large patches have been cleared than small patches. Dry rainforest on unconsolidated sediments and shale has been vastly reduced in area relative to dry rainforest on other substrates. National Parks secure some important remnants, including dry rainforest on alluvium in the south. However, dry rainforest is not adequately reserved across its geomorphic range of habitats and two out of eight broad floristic groups and seven out of 16 subgroups are not represented in reserves in the study area. Lantana Lantana camara L. and rubber vine Cryptostegia grandiflora Roxb. ex R. Br. are the most serious exotic species affecting dry rainforest in the study area. Lantana, at least, can increase the flammability of fire-sensitive dry rainforest vegetation. Provided that further land clearance is restricted, it is suggested that dry rainforest conservation is compatible with cattle grazing given appropriate active management. However, the preservation of dry rainforest will require management of the broader landscape, and small reserves that do not contain extensive areas of surrounding habitat may not be secure in the long term.

Floristics and Environmental Relations of Inland Dry Rainforest in North Queensland, Australia

Site-species data were collected from inland dry rainforest of north Queensland. The extent of patches declines with distance from the coast and they do not occur where rainfall is less than about 500mm per annum. TWINSPAN derived eight broad groups and sixteen sub- groups of the floristic continuum of rainforest in the study area. The floristic sub-groups are restricted within regions of the study area and most occur over a wide range of geological substrates and landforms. The primary floristic gradient is related to a latitudinal trend coinciding with the coefficient of variation of monthly precipitation, and a secondary gradient to distance from the coast and mean annual precipitation. The placement of dry rainforest from the study area within existing schemes is examined and the past terminology of Australian rainforest from relatively dry environments is discussed. Nearly half of the dry rainforest flora is obligately associ- ated with that environment. Although the flora is fairly spe- cialized to the rainforest environment, 87% of the inland woody species inventoried during this study are also known to occur within 1 km of the coast. It is argued that the wide- spread nature of the flora, the lack of specialization to habitat, and the existence of relatively complex dry rainforest on basalt lava flows of late Pleistocene age are consistent with a relatively recent invasion of this region of Queensland by this vegetation type since drier times during the last Glacial cycle.

Wildlife of Lancewood (Acacia Shirleyi) Thickets and Woodlands in Northern Australia. 2. Comparisons With Other Environments of the Region (Acacia Woodlands, Eucalyptus Savanna Woodlands and Monsoon Rainforests).

Embedded in the extensive Eucalyptus open forests and savanna woodlands that dominate the northern Australian landscape are patches of monsoon rain forest and Acacia thickets and woodlands. In this paper, the vertebrate species composition of patches of lancewood (Acacia shirleyi) thickets and woodlands of the Northern Territory was compared with that of other environments of this region: pindan woodlands (A. eriopoda and A. tumida), gidgee woodlands (A. georginae), patches of monsoon rain forests and the extensive Eucalyptus open forests and woodlands. The vertebrate fauna of lancewood thickets is distinct for that of Eucalyptus open forests, and has fewer species. Differences in species composition and richness are associated with substantial differences in resource availability, with lancewood thickets having far less grass cover (and hence relatively few granivorous birds and rodents, but more ground-feeding insectivorous and omnivorous birds), fewer nectar-bearing flowers (and hence fewer nectarivorous birds) and lower structural and floristic diversity than Eucalyptus forests. There was little difference in species richness or total abundance between the three types of Acacia woodlands sampled. Lancewood thickets had fewer species than monsoon rain forests to coastal dry monsoon rain forests to inland dry monsoon rain forests to lancewood thickets to pindan woodlands to gidgee woodlands, in accord with the pronounced rainfall gradient of this region and with canopy cover and height. Within this broad continuum the three Acacia woodlands were most closely grouped. Species turnover along this gradient consisted of substantial decrease or loss of some foraging groups (e.g. frugivorous birds) or replacement of species within broad foraging groups. The faunal relationship of the monsoon rain forests and Acacia communities provides some support for considering these fire-sensitive environments as fragments of a formerly extensive continuum. Three species (Pomatostomus temporalis, Struthidea cinerea and Melanodryas cucullata), all ground-foraging insectivorous or omnivorous birds, were significantly associated with lancewood in this region, but all three have extensive ranges beyond this area.

The invasion of Lantana camara L. in Forty Mile Scrub National Park, north Queensland

Abstract Seventy‐three per cent of dry rainforest in Forty Mile Scrub National Park and large areas in adjacent savanna woodland have more than 5000 individuals per ha of lantana (Lantana camara L.). Transect studies in dry rainforest and savanna woodland across varying intensities of lantana infestation show a negative correlation between the density of lantana and tree cover in rainforest. The density of pig rooting is very high in areas of the dry rainforest on deep soil that was not heavily infested with lantana. It is suggested that the digging activities of these animals may cause tree death and subsequent increased light penetration, which favours lantana. The species richness of the dry rainforest declines as the density of lantana increases. However, the saplings and seedlings and the soil seed bank of dry rainforest and savanna woodland tree species have comparable densities in heavy and light lantana infestations. The proliferation of lantana results in the build up of heavy fuel loads across the boundary of dry rainforest and savanna woodland. Recent fires have killed the canopy trees in a large area of dry rainforest within the Park. Active management of Forty Mile Scrub National Park is urgent and some initiatives are suggested.