Numerous studies have shown reduced performance in plants that are surrounded by neighbours of the same species^1,2, a phenomenon known as conspecific negative density dependence (CNDD)³. A long-held ecological hypothesis posits that CNDD is more pronounced in tropical than in temperate forests^4,5, which increases community stabilization, species coexistence and the diversity of local tree species^6,7. Previous analyses supporting such a latitudinal gradient in CNDD^8,9 have suffered from methodological limitations related to the use of static data^10–12. Here we present a comprehensive assessment of latitudinal CNDD patterns using dynamic mortality data to estimate species-site-specific CNDD across 23 sites. Averaged across species, we found that stabilizing CNDD was present at all except one site, but that average stabilizing CNDD was not stronger toward the tropics. However, in tropical tree communities, rare and intermediate abundant species experienced stronger stabilizing CNDD than did common species. This pattern was absent in temperate forests, which suggests that CNDD influences species abundances more strongly in tropical forests than it does in temperate ones¹³. We also found that interspecific variation in CNDD, which might attenuate its stabilizing effect on species diversity^14,15, was high but not significantly different across latitudes. Although the consequences of these patterns for latitudinal diversity gradients are difficult to evaluate, we speculate that a more effective regulation of population abundances could translate into greater stabilization of tropical tree communities and thus contribute to the high local diversity of tropical forests.

Forage plants, as primary producers, play an essential role in maintaining populations of large herbivores. The availability and quality of these forage plants can affect the health and viability of these animals. Seasonally dry forests of Huai Kha Khaeng Wildlife Sanctuary and Huai Thab Salao-Huai Rabum Non-Hunting Area are recognized as one of the largest contiguous pieces of forests in mainland Southeast Asia and serve as a home to many large herbivore species, particularly banteng (Bos javanicus birmanicus). However, our understanding of forage plants and their dynamics is still limited. Therefore, the current study was undertaken to understand the dynamics of forage plants, prescribed burning effects, and the associated environmental factors. During 2018–2019, the results showed that the highest forage availability was in June after the prescribed burns at 156.2–252.6 kg ha⁻¹ and the lowest in February before the burning at 16.8–39.8 kg ha⁻¹. Environmental factors that impacted the forage availability include canopy cover, tree density, tree basal area, soil bulk density, soil pH, and topography. However, the impacts of these factors varied among the studied plant life forms, suggesting the importance of active habitat management through prescribed burns and stand improvement to maintain sufficient forage for large herbivores in the future.

The 2018 arrival of African swine fever (ASF) in China was followed by reports of wild pig deaths across most countries in Southeast Asia. However, the magnitude and duration of population‐level impacts of ASF on wild pig species remain unclear. To elucidate the spatiotemporal spread of ASF in the region for native pig species, we gathered qualitative information on wild pig population dynamics in Southeast Asia between 2018 and 2024 from 88 expert elicitation questionnaires representing sites in 11 countries. Peak reported population declines occurred in 2021 and 2022, with more than half of respondents reporting declining wild pig populations, far higher than in earlier years. The reported declines waned to 44.23% in 2024, whereas simultaneously, the number of populations reported to be “increasing” increased from 11.3%–13.2% in 2019–2022 to 28.9% in 2024. These reports suggest that the ASF outbreak may have peaked for wild boars and bearded pigs in mainland Southeast Asia, Borneo, and Sumatra, with some subsequent recovery. However, the disease is still expanding into the ranges of island endemic species, such as new reports for the Sulawesi warty pig ( Sus celebensis ) in September of 2024. Island endemics remain particularly vulnerable to extinction from ASF and require urgent monitoring and conservation action.

Seedlings are an important stage for plant populations, as the abundance and rigor of seedlings can indicate a changing forest structure in the future. Studying the different traits of the seedling can represent how the plant grows. Biomass is one of the traits that can represent the plant’s performance and many other growth processes of the seedling. Several allometric equations have been developed to estimate tree biomass. However, allometric equations for the biomass of seedlings remains poorly studied, especially those from the tropics. The objective of this research is to create and develop a model that can be used to predict the biomass of seedlings, including total biomass, aboveground biomass, and belowground biomass, from root collar diameter, shoot height, main stem length, and wood density from 205 two-year-old seedlings from twenty tree species found in dry evergreen forest in Huai Kha Khaeng Wildlife Sanctuary, Uthai Thani, Thailand. The results showed that the root collar diameter, shoot height, and wood density could be used to create a model to best predict the seedling biomass. This model should be tested with other seedlings in the wild and other datasets to evaluate the performance of the model. To our knowledge, this study is among the first to provide the first allometry for seedlings in tropical dry evergreen forest. The results from this study will allow ecologists to monitor and examine the growth of the seedlings at all stages of life in dynamic tropical environments in the future.

Fire is a necessary disturbance in tropical deciduous forests, as it helps clear the understory community and allows regeneration of grasses and forbs for local wildlife. Huai Kha Khaeng Wildlife Sanctuary (HKK) and Huai Thab Salao-Huai Rabum Non-Hunting Area (HTS) are parts of a few places in Southeast Asia with deciduous forests. However, this area was heavily logged up until 1989, followed by a long period of fire suppression. The consequences of these changes on understory communities have not been investigated. Therefore, the current study aimed to examine the understory communities and their aboveground biomass before and after the annual prescribed burns in HKK and HTS. Understory plant composition and biomass were surveyed in November 2018 (before the fire) and May 2019 (three months after the fire) in 128 temporary plots, covering of deciduous dipterocarp forest, mixed deciduous forest, mixed deciduous forest with bamboo, and open area. We identified a total of 480 understory species, including 37 grass species, 214 forb species, 73 shrub species, 153 tree seedling species and three species of bamboo in the study plots. Grasses in the DDF plots were at 72.79 ± 22.41 kg ha${}^{-1}$, accounting for only ten percent of the understory plants in the plots. The understory community in the DDF plots was dominated by shrubs and tree seedlings of competing species, especially after the fire. The results suggested that past logging activities and long-term fire suppression had reduced the number of mature key dipterocarp forests and hindered the regeneration of grasses and forbs. Maintaining the structure of dipterocarp forests and sufficient food sources for the local wildlife species will require more active habitat management of the study areas.

Increased frequency and severity of droughts threatens forest health worldwide. Tree species‐specific adaptations—for example, dry‐season deciduousness in tropical seasonal forests—and individual traits—for example, size, crown position—shape drought resistance, but such resistance may be variable across species, microenvironments and drought events. Here, we assess growth responses of 1820 trees across 30 species to three climatically distinct droughts in a seasonally dry tropical forest in Western Thailand. Species and individuals exhibited a wide range of growth responses within each drought, and differences in response intensity and affect among the drought events. Deciduous and evergreen species were more sensitive to wet‐ and dry‐season drought respectively. While individuals with more exposed crowns tended to grow less in all droughts, stem diameter and topographic wetness had variable effects. Heterogeneous drought responses of species and individuals indicate potential biological insurance effects in diverse forests in the face of increased drought.