Distribution Of Rainforest Research Articles

Dipterocarpoidae genomics reveal their demography and adaptations to Asian rainforests

Dipterocarpoideae species form the emergent layer of Asian rainforests. They are the indicator species for Asian rainforest distribution, but they are severely threatened. Here, to understand their adaptation and population decline, we assemble high-quality genomes of seven Dipterocarpoideae species including two autotetraploid species. We estimate the divergence time between Dipterocarpoideae and Malvaceae and within Dipterocarpoideae to be 108.2 (97.8‒118.2) and 88.4 (77.7‒102.9) million years ago, and we identify a whole genome duplication event preceding dipterocarp lineage diversification. We find several genes that showed a signature of selection, likely associated with the adaptation to Asian rainforests. By resequencing of two endangered species, we detect an expansion of effective population size after the last glacial period and a recent sharp decline coinciding with the history of local human activities. Our findings contribute to understanding the diversification and adaptation of dipterocarps and highlight anthropogenic disturbances as a major factor in their endangered status.

Landscape heterogeneity drives spatial distribution of palm community in a Neotropical rainforest reserve affected by defaunation

Background: Our study presents the first assessment of the relationships between environmental heterogeneity and the palm community at the landscape scale at the northern boundary of tropical rainforest distribution in America.
 Question: How does landscape-level heterogeneity (edaphic, topographic as well as the density, diversity, and tree biomass) shapes the palm community in a protected reserve affected by defaunation?
 Study site and date: The study was carried out in Los Tuxtlas Tropical Biology Station, Veracruz, Mexico (2020).
 Methods: We delineated landscape units (LUs) based on soil and geomorphology to characterize the biophysical mosaic. We built rank-abundance curves to compare the palm richness and their abundance among LUs. Permutational multivariate analysis of variance (PERMANOVA) and nonmetric multidimensional scaling (NMDS) were applied to detect shifts in the palm community across LUs.
 Results: Integrating abiotic and biotic components by delimiting LUs allowed us to evaluate the multifactorial effect of environmental heterogeneity on the palm community. The density and composition of the palms changed significantly among the LUs, influenced by soil coarse fragments, elevation, slope inclination, and annual precipitation. Tree richness and density had a significant effect on the palm community only when analyzed in combination with the soil-topography variables.
 Conclusions: The results reveal that there is high edaphic and topographic heterogeneity that influences palm species distribution at the landscape scale. The environmental heterogeneity approach allows capturing novel abiotic variation to explain the distribution patterns of palm species and their coexistence in highly diverse tropical communities.

Comprehensive phylogenetic analyses of Orchidaceae using nuclear genes and evolutionary insights into epiphytism.

Orchidaceae (with >28,000 orchid species) are one of the two largest plant families, with economically and ecologically important species, and occupy global and diverse niches with primary distribution in rainforests. Among orchids, 70% grow on other plants as epiphytes; epiphytes contribute up to ~50% of the plant diversity in rainforests and provide food and shelter for diverse animals and microbes, thereby contributing to the health of these ecosystems. Orchids account for over two-thirds of vascular epiphytes and provide an excellent model for studying evolution of epiphytism. Extensive phylogenetic studies of Orchidaceae and subgroups have ;been crucial for understanding relationships among many orchid lineages, although some uncertainties remain. For example, in the largest subfamily Epidendroideae with nearly all epiphytic orchids, relationships among some tribes and many subtribes are still controversial, hampering evolutionary analyses of epiphytism. Here we obtained 1,450 low-copy nuclear genes from 610 orchid species, including 431 with newly generated transcriptomes, and used them for the reconstruction of robust Orchidaceae phylogenetic trees with highly supported placements of tribes and subtribes. We also provide generally well-supported phylogenetic placements of 131 genera and 437 species that were not sampled by previous plastid and nuclear phylogenomic studies. Molecular clock analyses estimated the Orchidaceae origin at ~132 million years ago (Ma) and divergences of most subtribes from 52 to 29 Ma. Character reconstruction supports at least 14 parallel origins of epiphytism; one such origin was placed at the most recent common ancestor of ~95% of epiphytic orchids and linked to modern rainforests. Ten occurrences of rapid increase in the diversification rate were detected within Epidendroideae near and after the K-Pg boundary, contributing to ~80% of the Orchidaceae diversity. This study provides a robust and the largest family-wide Orchidaceae nuclear phylogenetic tree thus far and new insights into the evolution of epiphytism in vascular plants.

Assessment of the Diversity, Distinctiveness and Conservation of Australia’s Central Queensland Coastal Rainforests Using DNA Barcoding

Globally threatened dry rainforests are poorly studied and conserved when compared to mesic rainforests. Investigations of dry rainforest communities within Australia are no exception. We assessed the community diversity, distinctiveness and level of conservation in Central Queensland coastal dry rainforest communities. Our three-marker DNA barcode-based phylogeny, based on rainforest species from the Central Queensland Coast, was combined with the phylogeny from Southeast Queensland. The phylogenetic tree and Central Queensland Coast (CQC) community species lists were used to evaluate phylogenetic diversity (PD) estimates and species composition to pinpoint regions of significant rainforest biodiversity. We evaluated the patterns and relationships between rainforest communities of the biogeographical areas of Central Queensland Coast and Southeast Queensland, and within and between Subregions. Subsequently, we identified areas of the highest distinctiveness and diversity in phylogenetically even rainforest communities, consistent with refugia, and areas significantly more related than random, consistent with expansion into disturbed or harsher areas. We found clear patterns of phylogenetic clustering that suggest that selection pressures for moisture and geology were strong drivers of rainforest distribution and species diversity. These results showed that smaller dry rainforests in Central Queensland Coast (CQC) represented areas of regional plant migration but were inadequately protected. To sustain species diversity and distribution under intense selection pressures of moisture availability and substrate type throughout this dry and geologically complex region, the future conservation of smaller patches is essential.

Is insect vertical distribution in rainforests better explained by distance from the canopy top or distance from the ground?

The way arthropods are distributed vertically in tropical forests has been of great interest with diversity often greatest at or near the canopy top. Typically, stratification is measured up from the ground but, since the height of trees reaching the canopy top can vary, we hypothesise that distance down from the canopy top, might better explain arthropod distributions. To test this samples were collected from Australian tropical rainforest trees in both dry and wet seasons by beating foliage from five trees for each of 11 tree species at set intervals down each tree. A total of 2628 arthropods were collected. Abundant groups were Araneae, Coleoptera, Formicidae, Blattodea and Homoptera. Coleoptera were sorted to species. Since the forest was naturally disturbed by storms, height of trees reaching the canopy top ranged 10–40 m. Our results suggested that the best fit for vertical stratification, either distance from ground or distance down from the canopy, were taxon specific. For ordinal richness and abundance of arthropods the best model was distance from the ground with decreasing trends from the ground. Similarly, distance from the ground best fitted abundances of spiders, cockroaches and Homoptera. In contrast, declination from the canopy top best fitted beetle species richness and abundance, and ant abundance. The effect of vertical stratification was, however, significant only for ants in dry season: abundance of ants decreased with increasing distance down from the canopy top. We were surprised to have found taxon-specific patterns, which may be explained by highly variable canopy tree height, creating vertically heterogeneous micro-habitat conditions in this forest system.

Velvet worm (Phylum Onychophora) on a sand island, in a wetland: Flushed from a Pleistocene refuge by recent rainfall?

AbstractVelvet worms (Onychophora) are restricted to moist, humid microclimates, but are poorly known from south‐east Queensland, Australia, where they are typically rainforest fauna. We made the unlikely observation of one of these invertebrates clinging to floating debris in a wetland on North Stradbroke Island. Palaeoecology of this wetland reveals that it once was within rainforest and has remained moist for at least the past 80 000 years, thus potentially harbouring an onychophoran population as a relic of a past broader, rainforest distribution. The presence of this animal, floating in the wetland, can be explained by recent climate, since the wetland filled following heavy rainfall shortly before the observation. This highlights the importance of groundwater‐fed wetlands as evolutionary refugia for moisture‐dependent biota.

Filters of floristic exchange: How traits and climate shape the rain forest invasion of Sahul from Sunda

AbstractAimTo evaluate how biogeographical and ecological processes influenced species distributions and community assembly in a continental rain forest flora with mixed biogeographical origins.LocationContinental Australia.MethodsWe identified 795 species with Sahul ancestry (Australian rain forest flora of Gondwanan origin) and 604 species with Sunda ancestry (rain forest plant lineages of Indo‐Malaysian origin) from a total of 1,872 free‐standing Australian woody rain forest taxa. We then compared the distribution of Sunda to Sahul species in relation to variation in species richness and phylogenetic endemism at continental scale, and local species distributions in available plot data from the Tropics (Cape York and the Australian Wet Tropics in northern Queensland) and subtropics (Nightcap‐Border Ranges, Washpool and Dorrigo, in northern New South Wales). We compared the dispersal and persistence characteristics, and key functional traits (leaf size, fruit size, wood density and maximum height at maturity) of the Sunda and Sahul components of the continental rain forest flora. The influence of climate (temperature) and local environmental (altitude) factors in driving fine‐scale distributional patterns was evaluated.ResultsSunda rain forest species richness decreased with increasing latitude but maintained high levels of endemism, including in the south. Sunda species traits suggest more efficient dispersal and faster growth than Sahul lineages. Resprouting (persistence) was less evident in species with Sunda than Sahul ancestry. We show that Sunda lineage distributions were influenced by interacting environmental and climatic factors, as well as historical contingencies.Main conclusionsEfficient dispersal and relatively fast growth likely facilitated the establishment and spread of Sunda lineages in Australia. However, the Sunda invasion was resisted in stable, saturated communities of Sahul lineages, and in the temperate south where climate acted as a strong filter. The results highlight the importance of integrating historical biogeography and contemporary ecological processes to study continental‐scale rain forest distribution and assembly.

Predicting temperate forest stand types using only structural profiles from discrete return airborne lidar

Light detection and ranging (lidar) data have been increasingly used for forest classification due to its ability to penetrate the forest canopy and provide detail about the structure of the lower strata. In this study we demonstrate forest classification approaches using airborne lidar data as inputs to random forest and linear unmixing classification algorithms. Our results demonstrated that both random forest and linear unmixing models identified a distribution of rainforest and eucalypt stands that was comparable to existing ecological vegetation class (EVC) maps based primarily on manual interpretation of high resolution aerial imagery. Rainforest stands were also identified in the region that have not previously been identified in the EVC maps. The transition between stand types was better characterised by the random forest modelling approach. In contrast, the linear unmixing model placed greater emphasis on field plots selected as endmembers which may not have captured the variability in stand structure within a single stand type. The random forest model had the highest overall accuracy (84%) and Cohen’s kappa coefficient (0.62). However, the classification accuracy was only marginally better than linear unmixing. The random forest model was applied to a region in the Central Highlands of south-eastern Australia to produce maps of stand type probability, including areas of transition (the ‘ecotone’) between rainforest and eucalypt forest. The resulting map provided a detailed delineation of forest classes, which specifically recognised the coalescing of stand types at the landscape scale. This represents a key step towards mapping the structural and spatial complexity of these ecosystems, which is important for both their management and conservation.

The relationship between climate change and the endangered rainforest shrub Triunia robusta (Proteaceae) endemic to southeast Queensland, Australia

Threatened species in rainforests may be vulnerable to climate change, because of their potentially narrow thermal tolerances, small population sizes and restricted distributions. This study modelled climate induced changes on the habitat distribution of the endangered rainforest plant Triunia robusta, endemic to southeast Queensland, Australia. Species distribution models were developed for eastern Australia at 250 m grids and southeast Queensland at 25 m grids using ground-truthed presence records and environmental predictor data. The species’ habitat distribution under the current climate was modelled, and the future potential habitat distributions were projected for the epochs 2030, 2050 and 2070. The eastern Australia model identified several spatially disjunct, broad habitat areas of coastal eastern Australia consistent with the current distribution of rainforests, and projected a southward and upslope contraction driven mainly by average temperatures exceeding current range limits. The southeast Queensland models suggest a dramatic upslope contraction toward locations where the majority of known populations are found. Populations located in the Sunshine Coast hinterland, consistent with past rainforest refugia, are likely to persist long-term. Upgrading the level of protection for less formal nature reserves containing viable populations is a high priority to better protect refugial T. robusta populations with respect to climate change.

Future Non-Analogue Climates for Scotland’s Temperate Rainforest

ABSTRACTTemperate rainforest is restricted to a globally rare set of climatic conditions. Scotland has among the best remaining examples of intact temperate rainforest in Europe, characterised ecologically by a unique assemblage of epiphytic bryophytes and lichens. Given climatic control on rainforest distribution and ecology, climate change is a probable risk to Scotland’s rainforest. This study investigated climate change impacts for 20 target sites, classified based on (i) bioclimatic conditions, and (ii) epiphytic diversity, into contrasting rainforest and more continental (non-rainforest) examples. Space-for-time matching identified climate analogues within the European conservation forest network, which at present have a climate similar to that expected of the target sites during the 2080s (WorldClim datasets). The results show that 2080s analogues for sites in more continental north-eastern Scotland occur in Wales and southern England. However, Scottish rainforest sites were their own ‘best analogues’ through to the 2080s, despite the fact that their climate is projected to change significantly; they had no suitable future analogue within Europe’s conservation forest network. These contrasting regional patterns highlight the need for a flexible approach to species conservation during climate change, including a strategy to cope with ecological uncertainty in Scotland’s zone of oceanic rainforest.

Tropical forest regeneration following land abandonment is driven by primary rainforest distribution in an old pastoral region

Context Tropical forest regeneration is increasingly prominent as agro-pastoral lands are abandoned. Regeneration is characterised as favouring ‘marginal’ lands; however, observations of its drivers are often coarse or simple, leaving doubt as to spatial dynamics and causation.

A review of the distribution of the Crested Eagle, Morphnus guianensis (Daudin, 1800) (Accipitridae: Harpiinae), including range extensions

Here we review the distribution of the Crested Eagle (Morphnus guianensis) in the Americas, and based on the Brazilian Harpy Eagle Conservation Program (PCGR) database, literature, online databases, zoos, wild and museum records, we provide an updated distribution map with 37 points outside the IUCN map; 16 were recorded close to the border of the map (up to 40 km), and do not expand or contribute to the distribution map. Far from the border (>40 km) we found 21 records, contributing to an expansion of the known range and habitat. At the northernmost extreme of distribution, the range was extended to southern Mexico; in Nicaragua, the range extension was farther south in the north, and two records extend the range to the southern border with Costa Rica. In Colombia, an old specimen is located between Darien Peninsula and the Perija Mountains. In Brazil a record from the ecotone between Cerrado and Gallery Forest, and another in an upland remnant of Atlantic Rainforest, expands the range towards central and southeastern Brazil, and to the Northeast, old records could expand the Atlantic Rainforest distribution towards the interior.

Aborigine‐managed forest, savanna and grassland: biome switching in montane eastern Australia

AbstractAimTo assess hypotheses about the role of anthropogenic fire in the maintenance and origin of a fine‐scale vegetation mosaic of rain forest, eucalypt savanna and grassland.LocationBunya Mountains, subtropical eastern Australia.MethodsA time series of vegetation maps was compiled from historical and recent aerial photography and field surveys. Geospatial models were constructed of environmental domains for rain forest, savanna and grassland, and for areas of biome change. Grassland soils were analysed for carbon isotope ratios (δ13C), and radiocarbon (14C) dates were acquired for bulk samples from a range of depths.ResultsAnalysis revealed weak associations between topography and the distribution of rain forest, savanna and grassland, and their patterns of recent change. Grassland occupied an environmental domain intermediate between rain forest and savanna and was more than four times as likely to occur within a matrix of rain forest rather than savanna. There was a large proportional reduction in the area of both grassland (−35%) and savanna (−19%) between 1961 and 2006 because of the expansion of rain forest. However, the greater initial extent of savanna meant that the areal loss of savanna was an order of magnitude greater than for grassland (1433 vs. 146 ha). There was no evidence of abrupt changes in δ13C in grassland soil profiles, indicating stability of the vegetation over the last 2000 years.Main conclusionsThere is no simple gradient in ‘tree suitability’ from rain forest, through savanna, to treeless grassland on the Bunya Mountains. A general absence of fire since the 19th century has greatly reduced the extent of grassy savanna and grassland formations, to the advantage of rain forest. These results support the hypothesis that the vegetation mosaic on the Bunya Mountains is a cultural artefact and testament to millennia of skilful and persistent burning. We could not conclusively reject the hypothesis that the grasslands are Pleistocene relicts that have declined throughout the Holocene; nonetheless, an explanation more consistent with the evidence overall is that the grasslands must have had periods of expansion during the Holocene, probably as a consequence of severe fires that have destroyed patches of rain forest.

Two new subspecies of the leaf-tailed gecko Phyllurus ossa (Lacertilia: Carphodactylidae) from mid-eastern Queensland, Australia.

Following the discovery of a new population of Phyllurus ossa on Whitsunday Island in the Cumberland Island Group, eastern Queensland, we conducted both genetic and morphological analyses to assess differences between all known populations. The analyses revealed three genetically distinct, morphologically diagnosable, geographical units. The differences are such that we recognise these as subspecies: Phyllurus ossa ossa restricted to the Mt Ossa/Mt Pelion/ Mt Charlton/ St Helens Gap area; P. ossa hobsoni subsp. nov. on Mt Dryander and in the Conway Range and P. ossa tamoya subsp. nov. currently only known from Whitsunday Island. There are now 11 recognised taxa in Phyllurus. The three P. ossa subspecies are narrowly distributed and closely associated with exposed rock in low to mid-elevation vine forests. Their current distributions are shaped by past climate change that progressively contracted and fragmented the distribution of rainforests in eastern Australia. The recognition of these subspecies has land management/conservation implications.

Palaeo-precipitation is a major determinant of palm species richness patterns across Madagascar: a tropical biodiversity hotspot.

The distribution of rainforest in many regions across the Earth was strongly affected by Pleistocene ice ages. However, the extent to which these dynamics are still important for modern-day biodiversity patterns within tropical biodiversity hotspots has not been assessed. We employ a comprehensive dataset of Madagascan palms (Arecaceae) and climate reconstructions from the last glacial maximum (LGM; 21 000 years ago) to assess the relative role of modern environment and LGM climate in explaining geographical species richness patterns in this major tropical biodiversity hotspot. We found that palaeoclimate exerted a strong influence on palm species richness patterns, with richness peaking in areas with higher LGM precipitation relative to present-day even after controlling for modern environment, in particular in northeastern Madagascar, consistent with the persistence of tropical rainforest during the LGM primarily in this region. Our results provide evidence that diversity patterns in the World's most biodiverse regions may be shaped by long-term climate history as well as contemporary environment.

Update: Of refugia and colonization, an innovative use of biogeography for climate studies

ISSN 1948-6596 require a careful consideration of exactly what constitutes a random and a structured matrix with respect to species nesting and spatial turn- over. But they should be conducted before at- tempting a meta-analysis of published empirical matrices. Second, this index, like most other meas- ures of nestedness and beta diversity, assumes that island censuses are complete and there are no undetected species. Anne Chao and colleagues have recently modified classic similarity indices to take into account undetected shared species. The presence of undetected species biases the un- modified indices towards underestimating shared species (and hence over-estimating beta diver- sity). It is not yet clear how serious of a problem this is for Baselga's (2009) proposed partition. news and update Baselga (2009) has made an innovative contribu- tion that deserves further exploration. Baselga, A. (2009) Partitioning the turnover and nest- edness components of beta diversity. Global Ecology and Biogeography, doi:10.1111/j.1466- 8238.2009.00490.x. Nicholas J. Gotelli Department of Biology, University of Ver- mont, USA e-mail: Nicholas.Gotelli@uvm.edu http://www.uvm.edu/~ngotelli/ homepage.html Edited by Thiago F. Rangel update Of refugia and colonization, an innovative use of biogeography for climate studies A beautiful sight in Glacier National Park is found along the Trail of the Cedars, a stand of western red cedar (Thuja plicata) replete with mossy rocks and cold running waters. This tree, and western hemlock (Tsuga heterophylla), are emblematic of the northern coastal temperate rainforests of the western US and Canada. However, they are also found over 160 kilometers to the east, across a large expanse of sagebrush steppe, on the west- ern flank of the Rocky Mountains. This well known disjunct rainforest distribution is the subject of a new biogeographic study titled, “The coastal- disjunct mesic flora in the inland Pacific Northwest of USA and Canada: refugia, dispersal and disequi- librium” by Daniel Gavin, professor of Geography at the University of Oregon. Dr Gavin analyzed the patterns of biodiversity between the coastal populations and northern and southern interior populations of 67 vascular plant species, all com- ponents of the temperate rainforest group. He used the biogeographic patterns to explore the possible interactions between species richness, climate change, and glaciation. The study exam- ines how species richness varies with climate; how distribution patterns may have been affected by glaciated versus un-glaciated areas in the interior; and whether life history characteristics such as seed dispersal mode and growth habit help ex- plain the current extent of the species analyzed. Dr. Gavin mapped each plant’s range distri- bution to 50x50 km grid cells using a variety of reference materials. He then examined patterns of species richness, according to life history char- acteristics and climate as defined in the PRISM data sets. The study used regression models of species richness as a function of Actual Evapotran- spiration (AET) in the coastal regions (most mesic and specious) to develop expected levels of spe- cies richness for the AET of more recently suitable interior regions. This permitted regional quantifi- cation of the level of disequilibrium from expected species richness, an indication of incomplete colo- nization by the regional flora. The northern inte- rior was most in disequilibrium, indicating that many species have yet to disperse into the area. Since several sources of colonizers exist, the impli- cation is that some plant species may have a diffi- cult time dispersing into newly suitable habitats across a fragmented landscape under future cli- mate change. frontiers of biogeography 1.2, 2009 — © 2009 the authors; journal compilation © 2009 The International Biogeography Society

Rainforest and savanna landscape dynamics in New Caledonia: Towards a mosaic of stable rainforest and savanna states?

AbstractStable forested environments can be converted to savanna in response to changes in environmental disturbances. New Caledonia is a biodiversity hotspot; significant ecological and economic resources would be lost if forests were turned into savanna by anthropogenic environmental changes. On the landscape scale, systems that have undergone shifts of this kind are characterized by sharp forest–savanna boundaries and mosaic‐like distributions of savanna and forest. Understanding the locations and the dynamics of such boundaries is a challenge for ecologists and is critical for landscape management and biodiversity conservation. Using a time series of aerial photographs (1955–2000) and a forest habitat suitability map, we tested the hypothesis that topography and spatial processes, especially those relating to fire spread and seed dispersal, are the main determinants of the spatial distribution of rainforest and savanna in a New Caledonian landscape covering 24 km2. Within the studied landscape, the overall forest coverage decreased by 24% between 1976 and 2000. This was primarily due to the contraction of forests on west‐facing slopes, which accounted for about 90% of the total loss. Conversely, the east‐facing forests seemed to have contracted extensively prior to the studied period, and were confined to refuges. A habitat suitability index calculated from the landscape's topographical features using generalized additive models accurately predicted both the presence of forests and the probability of forest expansion/contraction. We also provide evidence that spatial processes such as fire spread and seed dispersal limit the expansion and contraction of forests. Our results suggest that rainforests on west‐facing slopes in New Caledonia will be progressively destroyed by fire until they are restricted to refuges along thalwegs and creeks, as appears to have already happened for their east‐facing counterparts.

Firescape ecology: how topography determines the contrasting distribution of fire and rain forest in the south-west of the Tasmanian Wilderness World Heritage Area

Aim To test the hypothesis that ‘islands’ of fire-sensitive rain forest are restricted to topographic fire refugia and investigate the role of topography–fire interactions in fire-mediated alternative stable state models. Location A vegetation mosaic of moorland, sclerophyll scrub, wet sclerophyll eucalypt forest and rain forest in the rugged, fire-prone landscapes of south-west Tasmania, Australia. Methods We used geospatial statistics to: (1) identify the topographic determinants of rain forest distribution on nutrient-poor substrates, and (2) identify the vegetation and topographic variables that are important in controlling the spatial pattern of a series of very large fires (> 40,000 ha) that were mapped using Landsat Thematic Mapper (TM) satellite imagery. Results Rain forest was more likely to be found in valleys and on steep southfacing slopes. Fires typically burned within highly flammable treeless moorland and stopped on boundaries with less flammable surrounding vegetation types such as wet sclerophyll forest and rain forest. Controlling for the effect of vegetation, fires were most likely to burn on flats, ridges and steep north-facing slopes and least likely to burn in valleys and on steep south-facing slopes. These results suggest an antagonism between fire and rain forest, in which rain forest preferentially occupies parts of the landscape where fire is least likely to burn. Main conclusions The distribution of rain forest on nutrient-poor substrates was clearly related to parts of the landscape that are protected from fire (i.e. topographic fire refugia). The relative flammability of vegetation types at the landscape scale offers support to the proposed hierarchy of fire frequencies (moorland > scrub > wet sclerophyll > rain forest) that underpins the ecological models proposed for the region. The interaction between fire occurrence and a range of topographic variables suggests that topography plays an important role in mediating the fire–vegetation feedbacks thought to maintain vegetation mosaics in south-west Tasmania. We suggest that these fire–topography interactions should be included in models of fire-mediated alternative stable vegetation states in other fire-prone landscapes.

Palaeoecology of Southeast Asian megafauna‐bearing sites from the Pleistocene and a review of environmental changes in the region

AbstractAim To reconstruct the palaeoenvironments of megafauna‐bearing sites from Pleistocene Southeast Asia, and to describe general environmental changes in the region.Location Indochina and Sundaland, including Myanmar, Laos, Vietnam, Cambodia, Thailand, the Malay Peninsula, Borneo, Sumatra and Java.Methods This study reconstructs the habitat types of 25 Pleistocene sites in Southeast Asia through a synecological (community‐based) method. This method specifically targets medium‐ and large‐bodied mammals, and ecovariables that could be directly assessed from species lists were chosen. The methods allow the reconstruction of fossil sites as closed (continuous tree cover), mixed (heterogeneous tree cover) and open (very limited to no tree cover) through discriminant functions analysis of community guild structure.Results Four Pleistocene sites can confidently be assigned to one of the three habitat types. Tam Hang (south), a Middle Pleistocene site from Laos, is classified as mixed. Ban Fa Suai, a Middle Pleistocene site from Thailand, is also classified as mixed. Trinil, a Middle Pleistocene site from Java, is classified as open. Lastly, Hang Hum II, a Late Pleistocene site from Vietnam, is classified as open. Insufficient species are present in the fossil faunas of remaining sites to allow statistically confident habitat assignment. Nevertheless, conditional habitat assignments can be achieved, and these are largely congruent with other palaeoenvironmental evidence.Main conclusions Medium‐ and large‐bodied mammals are the most frequently recovered mammals from Pleistocene sites in Southeast Asia. Previous palaeoenvironmental reconstructions of these sites have been hampered by this body size bias, as well as by limited site and faunal descriptions. However, our analysis demonstrates that reconstructions can still be achieved for megafauna‐bearing sites in the region. The reconstructions suggest that through much of the Pleistocene, Southeast Asia had significant areas of mixed habitats, and that the widespread distribution of rain forests, such as found today, was a relatively rare phenomenon.

The current refugial rainforests of Sundaland are unrepresentative of their biogeographic past and highly vulnerable to disturbance

Understanding the historical dynamics of forest communities is a critical element for accurate prediction of their response to future change. Here, we examine evergreen rainforest distribution in the Sunda Shelf region at the last glacial maximum (LGM), using a spatially explicit model incorporating geographic, paleoclimatic, and geologic evidence. Results indicate that at the LGM, Sundaland rainforests covered a substantially larger area than currently present. Extrapolation of the model over the past million years demonstrates that the current "island archipelago" setting in Sundaland is extremely unusual given the majority of its history and the dramatic biogeographic transitions caused by global deglaciation were rapid and brief. Compared with dominant glacial conditions, lowland forests were probably reduced from approximately 1.3 to 0.8 x 10(6) km(2) while upland forests were probably reduced by half, from approximately 2.0 to 1.0 x 10(5) km(2). Coastal mangrove and swamp forests experienced the most dramatic change during deglaciations, going through a complete and major biogeographic relocation. The Sundaland forest dynamics of fragmentation and contraction and subsequent expansion, driven by glacial cycles, occur in the opposite phase as those in the northern hemisphere and equatorial Africa, indicating that Sundaland evergreen rainforest communities are currently in a refugial stage. Widespread human-mediated reduction and conversion of these forests in their refugial stage, when most species are passing through significant population bottlenecks, strongly emphasizes the urgency of conservation and management efforts. Further research into the natural process of fragmentation and contraction during deglaciation is necessary to understand the long-term effect of human activity on forest species.