From 1999 onwards, level, lowland forests (altitude < 150 m, slopes < 10°) in the Tanintharyi Region of southern Myanmar have been cleared on a large scale and replaced by oil palm plantations. This has resulted in a drastic decline in suitable habitat for several species, including Gurney's pitta Hydrornis gurneyi (Passeriformes, Pittidae). The habitat for this species has decreased by > 80%, leading to its categorization as Critically Endangered on the IUCN Red List in 2019. As threats in the region have continued, we updated information on the status of the species’ habitat in January 2020, and examined forest loss in the three strongholds where the species still persists in the wild. Since the previous estimate in 2017, suitable habitat in these locations has decreased by 8% (from 656 to 603 km2), with > 10% of the remaining area now in fragments of < 1 km2, which are unsuitable for the mid- to long-term survival of the species. Forest degradation and edge effects from increased fragmentation have led to further loss of suitable habitat in these strongholds. Projections indicate that unless conservation action is taken, all suitable habitat will disappear by 2080. The main threat to the long-term survival of Gurney's pitta is the lack of legal protection of primary lowland forests, resulting in uncontrolled clearance for small- and large-scale agriculture and industrial development. We provide recommendations to reduce the rate of loss of the remaining suitable habitat for the species.

Plant biodiversity is threatened by habitat loss, fragmentation and invasion by exotic species, but the effects of these disturbances on individual plant species are rarely quantified. Since the 1950s, brigalow Acacia harpophylla forests in Australia have been extensively cleared and converted to pastures dominated by exotic grasses. Here we assess the habitat requirements, population numbers and threats for four poorly known bush tomato species, Solanum adenophorum, Solanum dissectum, Solanum elachophyllum and Solanum johnsonianum. Herbarium records and surveys demonstrated a strong association of all four species with brigalow habitat, although S. elachophyllum also occurred in other habitat. We derived historical and current population estimates from plant densities at current sites and the area of mapped brigalow habitat. Density estimates are imprecise because the survey data vary greatly, but the assessment indicates the populations of all four species have declined > 93%. Solanum dissectum and S. johnsonianum did not persist in cleared brigalow habitat, whereas S. adenophorum and S. elachophyllum had some capacity to persist in clearings. None of the species occur where the exotic grass cover is > 40%. Between 27% and 57% of the records of the four species are in brigalow remnants with a high edge-to-area ratio or open canopy (< 50% cover), making them highly vulnerable to invasive grasses. We recommend the categorization of S. dissectum and S. johnsonianum as Critically Endangered, S. adenophorum as Vulnerable and S. elachophyllum as Near Threatened.

This paper investigates the relationships among land-use change, biological invasion, and interspecific competition in a tropical ecosystem by linking a behavioral model of land conversion by agriculture and an ecological model of interspecific competition between a native species and an exotic invader. The model is used to examine how relative farm prices and access to forest areas influence land clearing and thus the ability of the invasive species to eliminate the native species. Simulations show that only a 20% rise in relative prices and a 2.75% increase in forest access are necessary for this outcome to occur.