Humid tropical rain forest has expanded into eucalypt forest and savanna over the last 50 years

Tropical rain forest expansion and savanna woody vegetation thickening appear to be a global trend, but there remains uncertainty about whether there is a common set of global drivers. Using geographic information techniques, we analyzed aerial photography of five areas in the humid tropics of northeastern Queensland, Australia, taken in the 1950s and 2008, to determine if changes in rain forest extent match those reported for the Australian monsoon tropics using similar techniques. Mapping of the 1950s aerial photography showed that of the combined study area (64,430 ha), 63% was classified as eucalypt forests/woodland and 37% as rain forest. Our mapping revealed that although most boundaries remained stable, there was a net increase of 732 ha of the original rain forest area over the study period, and negligible conversion of rain forest to eucalypt forest/woodland. Statistical modeling, controlling for spatial autocorrelation, indicated distance from preexisting rain forest as the strongest determinant of rain forest expansion. Margin extension had a mean rate across the five sites of 0.6 m per decade. Expansion was greater in tall open forest types but also occurred in shorter, more flammable woodland vegetation types. No correlations were detected with other local variables (aspect, elevation, geology, topography, drainage). Using a geographically weighted mean rate of rain forest margin extension across the whole region, we predict that over 25% of tall open forest (a forest type of high conservation significance) would still remain after 2000 years of rain forest expansion. This slow replacement is due to the convoluted nature of the rain forest boundary and the irregular shape of the tall open forest patches. Our analyses point to the increased concentration of atmospheric CO2 as the most likely global driver of indiscriminate rain forest expansion occurring in northeastern Australia, by increasing tree growth and thereby overriding the effects of fire disturbance

Assisted natural regeneration accelerates recovery of highly disturbed rainforest

Large areas of rainforests in Australia and other tropical regions have been extensively cleared since the mid-19th century. As abandoned agro-pastoral land becomes increasingly prominent, there is an ongoing need to identify cost-effective approaches to reinstate forest on these landscapes. Assisted regeneration is a potentially lower cost restoration approach which aims to accelerate forest recovery by removing barriers to natural regeneration. However, despite being widely used its ecological benefits are poorly quantified, particularly on long cleared and grazed land. This study quantified the benefits of assisted regeneration on previously cleared land in a subtropical rainforest ecosystem within eastern Australia. Three different site types were used (grazed, grazing excluded and grazing excluded plus assisted regeneration, each with a maximum distance of 120 m to remnant forest) to compare forest recovery up to 10 years after grazing was relieved with and without 4–6 years of assisted regeneration. Assisted regeneration sites showed a threefold increase in canopy cover, fourfold increase in native tree and shrub species richness and over 40 times greater native stem density compared to nonassisted regeneration sites. Stimulation of native recruitment appears dependent on the simultaneous removal of multiple barriers to regeneration, with the exclusion of grazing alone insufficient. This demonstrates the additional ecological benefits arising from investment in assisted regeneration. It offers considerable promise as a cost-effective tool for accelerating and improving reinstatement of forest on retired agro-pastoral land in the humid subtropics

The role of topography and plant functional traits in determining tropical reforestation success

1. Early establishment and sapling growth is a key phase in ensuring cost-effective reforestation success in relation to biodiversity outcomes. Therefore, species selection must consider the interaction between plant functional traits and the often-challenging and heterogeneous biophysical environment of degraded landscapes

Vegetation structure and ground cover attributes describe the occurrence of a newly discovered carnivorous marsupial on the Tweed Shield Volcano caldera, the endangered black-tailed dusky antechinus (Antechinus arktos)

The black-tailed dusky antechinus (Antechinus arktos) is a recently discovered, endangered, carnivorous marsupial mammal endemic to the Tweed Shield Volcano caldera, straddling the border between Queensland and New South Wales in eastern Australia. The species' preference for cool, high-altitude habitats makes it particularly vulnerable to a shifting climate as these habitats recede. Aside from basic breeding and dietary patterns, the species' ecology is largely unknown. Understanding fine-scale habitat attributes preferred by this endangered mammal is critical to employ successful conservation management. Here, we assess vegetation attributes of known habitats over three sites at Springbrook and Border Ranges National Parks, including detailed structure data and broad floristic assessment. Floristic compositional assessment of the high-altitude cloud rainforest indicated broad similarities. However, only 22% of plant species were shared between all sites indicating a high level of local endemism. This suggests a diverse assemblage of vegetation across A. arktos habitats. Habitat characteristics were related to capture records of A. arktos to determine potential fine-scale structural habitat requirements. Percentage of rock cover and leaf litter were the strongest predictors of A. arktos captures across survey sites, suggesting a need for foraging substrate and cover. Habitat characteristics described here will inform predictive species distribution models of this federally endangered species and are applicable to other mammal conservation programs.</p