Forests Of Southeast Asia Research Articles

All tidal wetlands are blue carbon ecosystems.

Managing coastal wetlands is one of the most promising activities to reduce atmospheric greenhouse gases, and it also contributes to meeting the United Nations Sustainable Development Goals. One of the options is through blue carbon projects, in which mangroves, saltmarshes, and seagrass are managed to increase carbon sequestration and reduce greenhouse gas emissions. However, other tidal wetlands align with the characteristics of blue carbon. These wetlands are called tidal freshwater wetlands in the United States, supratidal wetlands in Australia, transitional forests in Southeast Asia, and estuarine forests in South Africa. They have similar or larger potential for atmospheric carbon sequestration and emission reductions than the currently considered blue carbon ecosystems and have been highly exploited. In the present article, we suggest that all wetlands directly or indirectly influenced by tides should be considered blue carbon. Their protection and restoration through carbon offsets could reduce emissions while providing multiple cobenefits, including biodiversity.

No evidence of carbon storage usage for seed production in 18 dipterocarp masting species in a tropical rain forest.

Most canopy species in lowland tropical rain forests in Southeast Asia, represented by Dipterocarpaceae, undergo mast reproduction synchronously at community level during a general flowering event. Such events occur at irregular intervals of 2-10years. Some species do not necessarily participate in every synchronous mast reproduction, however. This may be due to a lack of carbohydrate resources in the trees for masting. We tested the hypothesis that interspecific differences in the time required to store assimilates in trees for seed production are due to the frequency of masting and/or seed size in each species. We examined the relationship between reproductive frequency and the carbon accumulation period necessary for seed production, and between the seed size and the period, using radiocarbon analysis in 18 dipterocarp canopy species. The mean carbon accumulation period was 0.84years before seed maturation in all species studied. The carbon accumulation period did not have any significant correlation with reproductive frequency or seed size, both of which varied widely across the species studied. Our results show that for seed production, dipterocarp masting species do not use carbon assimilates stored for a period between the masting years, but instead use recent photosynthates produced primarily in a masting year, regardless of the masting interval or seed size of each species. These findings suggest that storage of carbohydrate resources is not a limiting factor in the masting of dipterocarps, and that accumulation and allocation of other resources is important as a precondition for participation in general flowering.

Degradation increases peat greenhouse gas emissions in undrained tropical peat swamp forests

AbstractTropical peat swamp degradation can modify net peat greenhouse gas (GHG) emissions even without drainage. However, current Intergovernmental Panel on Climate Change (IPCC) guidelines do not provide default emission factors (EF) for anthropogenically-degraded undrained organic soils. We reviewed published field measurements of peat GHG fluxes in undrained undegraded and degraded peat swamp forests in Southeast Asia (SEA) and Latin America and the Caribbean (LAC). Degradation without drainage shifted the peat from a net CO2 sink to a source in both SEA (− 2.9 ± 1.8 to 4.1 ± 2.0 Mg CO2–C ha−1 yr−1) and LAC (− 4.3 ± 1.8 to 1.4 ± 2.2 Mg CO2–C ha−1 yr−1). It raised peat CH4 emissions (kg C ha−1 yr−1) in SEA (22.1 ± 13.6 to 32.7 ± 7.8) but decreased them in LAC (218.3 ± 54.2 to 165.0 ± 4.5). Degradation increased peat N2O emissions (kg N ha−1 yr−1) in SEA forests (0.9 ± 0.5 to 4.8 ± 2.3) (limited N2O data). It shifted peat from a net GHG sink to a source in SEA (− 7.9 ± 6.9 to 20.7 ± 7.4 Mg CO2-equivalent ha−1 yr−1) and increased peat GHG emissions in LAC (9.8 ± 9.0 to 24.3 ± 8.2 Mg CO2-equivalent ha−1 yr−1). The large observed increase in net peat GHG emissions in undrained degraded forests compared to undegraded conditions calls for their inclusion as a new class in the IPCC guidelines. As current default IPCC EF for tropical organic soils are based only on data collected in SEA ombrotrophic peatlands, expanded geographic representation and refinement of peat GHG EF by nutrient status are also needed.

Ectomycorrhizal fungi inoculation on Shorea balangeran and Tristaniopsis obovata in peatland ecosystems

The majority of tropical forest plants form associations with Ectomycorrhizal fungi (EMF). These symbiotic fungi play important roles in promoting the survivability of their host, improving their productivity, and increasing microbial biodiversity in the underground. In order to promote the survivability and the growth of two peatlands tree species (Shorea balangeran and Tristaniopsis obovata) on Central Kalimantan and South Sumatra, their seedlings were inoculated with EMF. The aim of this study was to evaluate the effectiveness of EMF inoculation by identifying the EMF that colonized the root tips of Shorea balangeran and Tristaniopsis obovata using a molecular approach after 3 years of planting. The results shows that eight molecular operational taxonomic units (MOTU) were successfully identified out of twelve EMF root tips. Most of these MOTU identified as Thelephoraceae family, which is a cosmopolitan fungus in Southeast Asia forests. However, none of the inoculated EMF were detected in the root tips, indicating the occurrence of natural succession process, where native EMF in the field replacing inoculated EMF in the nursery.

Greater soil carbon losses from secondary than old-growth tropical forests

Tropical forests play a crucial role in mediating the global carbon cycle and climate. Southeast Asian tropical forests are experiencing ongoing threats of deforestation and degradation. There is an urgent need to determine how the conversion from primary forest to secondary forest coverage may impact C stocks and cycling. While old-growth forests typically contain larger stores of C aboveground than secondary forests, past research has found varied results for belowground soil C storage and fluxes between tropical forest types. We examined differences in annual soil C efflux in a 2-ha old-growth and an adjacent 2-ha 70-year-old secondary ForestGEO plots in Bukit Timah Nature Reserve in Singapore. We hypothesized that the secondary forest would have greater soil C efflux rates than the old-growth forest and explored several potential drivers of soil C efflux including abiotic and biotic factors such as soil moisture, fine root biomass, and ectomycorrhizal association. We found that the hypothesis was supported, suggesting that belowground carbon dynamics fundamentally differ with forest age. Additionally, we found that fine root biomass was the best predictor of soil C efflux in the secondary forest and soil moisture in the old-growth forest. The difference in soil C efflux between forest types indicates that with continued degradation of old-growth forests in Southeast Asia, conversion of old-growth forests into secondary forests may drive greater C loss from soils even after 70 years of regrowth.

Comparative physiology of canopy tree leaves in evergreen and deciduous forests in lowland Thailand

The typical seasonally dry forests in Southeast Asia are the mixed deciduous forest (MDF), dry dipterocarp (deciduous) forest (DDF), and dry evergreen forest (DEF). We obtained 21 physiological traits in the top/sunlit leaves of 107, 65 and 51 tree species in MDF, DEF and DDF, respectively. Approximately 70%, 95% and 95% of canopy tree species which consist of MDF, DEF and DDF are sampled, respectively. Light-saturated photosynthetic rates (Asat) exhibit a positive correlation with foliar nitrogen (N) and phosphorus (P) on leaf mass and area bases across tree species. Decreased leaf mass-based P reduces the positive slope of the mass-based N and Asat relationship across species and habitats. The differences in nutrient and water use and leaf habits are well matched to the variation in soil properties among the forest types, highlighting the reliability of this comprehensive database for revealing the mechanism of niche segregation based on edaphic factors.

Local People's Attitudes Towards Mangrove Conservation Effort in East Kalimantan, Indonesia

Background: Human activity has accelerated the degradation of mangrove forests in Southeast Asia, especially in Indonesia. The Government has encouraged conservation efforts towards the woods to cope with this problem. Participation of local people is considered necessary nowadays to understand their attitudes related to such issues. Studies are limited in Indonesia's context, especially in East Kalimantan province's case concerned with a heterogeneous community regarding socioeconomic and limited access to conservation activities. Aim: This study aims to understand how local people could have different participation and willingness to participate (WTP) as the embodiment of their attitudes towards conservation activities and how their reasons are associated with the heterogenous characteristics by taking the location of Margomulyo Mangrove Conservation Area (MMCA) Balikpapan, East Kalimantan. Method: This study uses a qualitative approach combining interviews, observation, and document collection methods. The data is analyzed inductively using coding stages from Miles, Huberman, and Saldaña. Findings: This study reveals positive attitudes by different participation from local people that presented as a heterogenous community. Reasons for involvement vary and are associated mainly with occupation, experiences in mangrove conservation activities that gave them access to the projects, and good networks among local people. Meanwhile, an excellent social relationship contributes to the WTP of local people in the projects with different preference types of activities. This study's findings suggest equitable management for local people by the Government by considering adequate social capital that already exists in the community.

Bioactive Compounds and Health-Promoting Properties of Elephant Apple (Dillenia indica L.): A Comprehensive Review.

Elephant apple (Dillenia indica L.) grows wild in Southeast Asia's forests, including in China, India, Nepal, Bangladesh, and Sri Lanka. Elephant apples are considered essential fruit crops because of their high nutritional value, which includes high levels of vitamin C, carbohydrates, fats, fibre, protein, minerals, and fatty acids. It is important to understand the nutritional value and health benefits of elephant apples in order to increase fruit intake in people's daily diets. The present review paper focuses on elephant apple's phytochemistry, bioactive compounds, therapeutic value, and medicinal capabilities for designing and developing a wide range of food formulations. Proteins, minerals, fats, crude fibre, carbohydrates, vitamin C, tannins, malic acid, and glucose are abundant in the leaves, bark, and fruit of the elephant apple. In addition to nutritional components, many phytochemicals found in elephant apples have been identified as bioactive compounds with a broad range of biological activities, the most prominent of which are antioxidant, anticancer, antidiabetic, and anti-inflammatory properties. Overall, elephant apple is a rich, natural source of bioactive compounds with potential applications in the production of value-added foods and nutraceuticals for disease prevention and management.

An historical reassessment of the maritime Southeast Asian forest and marine commodities trade and its implications for archaeological investigations of Asian contact in northern Australia

This paper reassesses the maritime Southeast Asian forest and marine commodities trade from the sixteenth century to World War I. The ‘Macassan’ traders who visited northern Australia were primarily from Makassar and southern Sulawesi (including Bugis, or Bajau and Sumbawan immigrants) and the Lesser Sunda Islands (to where these ethnic groups had migrated) but also included the Indigenous Australians who accompanied them on their voyages. Research into other ethnic groups (Chinese, Makassar-Malay, Seram Laut Islanders, Solorese and Timorese mariners) also associated with both northern Australia and the maritime Southeast Asian forest and marine trade suggests that they be included in the ‘Macassan’ group. Analysis of historical sources for the late nineteenth–early twentieth century Macassan trepang (sea cucumber) industry in north Australia demonstrates that perahu spare cargo capacity was filled with additional commodities when the trepang harvest was low, ensuring voyage profitability. Comparison of the maritime Southeast Asian trade with ethnographic, archaeological, historical, and linguistic evidence in northern Australia, suggests that 20 commodities were likely to have been exported from the latter, seven of which have never before been mentioned in the literature. Mapping of the Macassan routes transporting the 20 commodities shows that northern Australia was connected to a vast network of maritime Southeast and East Asian trade with global reach. The importance of these findings for Asian contact archaeology in northern Australia is threefold: (1) archaeologists should look beyond ceramic provenance, metal, and glass to seek material and chronological evidence for the extraction and processing of a wider range of forest and marine commodities; (2) evidence for the extraction of particular commodities might be a proxy for age estimation of a site; and (3) the origins of introduced material culture will reflect its East, South, and Southeast Asian and, ultimately, global connectivity.

Liana abundance and diversity increase along a successional gradient, even with homogeneous closed canopy

One-half of the pantropical forests are regrowth that develop in certain stages along the succession gradient. As lianas can colonize rapidly in disturbed areas, they play a key role in forest succession and carbon sequestration. However, current knowledge remains limited and is from only a few sites in neotropical forests. Here we investigated liana succession in a chronosequence located in a Southeast Asian Forest. We determined liana abundance (stem density, basal area, prevalence) and diversity along the succession gradient with ages in the range 3–100 years. We also analyzed community composition, size structure, and the correlation with host tree size. We found that liana abundance and diversity increased non-linearly along the succession gradient, suggesting that the stem exclusion stage (35–41 years)—homogeneous closed canopy with low light penetration—did not inhibit liana colonization. Assuming the reverse J-shaped distribution, we fitted the size structure of each plot with the exponential distribution. The results demonstrated no differences among the fitted parameters of plots in the stem exclusion and the old-growth stage, suggesting the same capability of recruitment and colonization in both stages. Furthermore, we found a weak correlation between liana and host tree size (R2 ≤ 0.16, which varied among plots, implying that many lianas recruited after the establishment of large host trees in the past. The results regarding community composition perhaps suggested a stochastic process of liana colonization during the early stage (3–20 years) because of high spatial heterogeneity (a mosaic of open area alternating with closed canopy). In the stem exclusion and old-growth stages, we observed a predictable trajectory, with the composition of plots in the same stage being clustered. This implied that forest structure or unpredictable treefall gaps of old-growth forests have a limited impact on community dissimilarity. Collectively, these results suggested that (1) some liana species may be generalists or even shade-tolerant species, or (2) there was no seed dispersal limitation in the landscape. The contrary direction of the succession patterns reported here suggests a need for more studies across tropical forests including investigating life history trade-offs such as light tolerance.

Effect of habitat structure on abundance and body conditions of two sympatric geckos, Cyrtodactylus saiyok and Cyrtodactylus tigroides, in the karst forest of western Thailand

ABSTRACT Deforestation is a major threat to biodiversity worldwide, especially in Southeast Asia. In western Thailand, reptiles are an important part of tropical rainforest ecosystems and karst forests. However, basic ecological studies of many species are largely lacking. Therefore, we studied two sympatric gecko species, Cyrtodactylus saiyok and C. tigroides, that inhabit karst forests and are restricted to western Thailand. We investigated the habitat variables that affect their abundance and body condition in Kanchanaburi Province in western Thailand. We found that the abundance of C. saiyok increased with increasing plant density and decreasing canopy cover. For both study species, body condition was positively correlated with canopy cover. The two species differed in their microhabitat use, and C. tigroides prefers more karst outcrops and stays higher above the ground. Our findings highlight the importance of an intact forest structure for the survival of geckos and thus reiterates that it is crucial to conserve karst forests in Southeast Asia.

Genetic structure and population history of a peat swamp forest tree species, Shorea albida (Dipterocarpaceae), in Brunei Darussalam.

Southeast Asia supports high biodiversity, in a mosaic of forest types formed by the expansion and contraction of habitats through past climate changes. Among the region's forest types, the geographical distribution of peat swamp forests has fluctuated intensely over the past 120,000 years. Most peat swamp forests in Southeast Asia are found in coastal regions and formed within the last 7,000 years after a decline in sea level. However, some peat swamps were initiated earlier on substrates of slightly higher elevation, and these peat swamps might have been refugia for peat swamp species in the last glacial period and the high sea level period. We assessed genetic diversity, genetic structure and divergence time of current genetic groups for Shorea albida in Brunei, an endemic tree species of Bornean peat swamp forests, using 18 microsatellite markers. Genetic diversity was not lower than has been found in other Shorea species, possibly because of the high density of S. albida in Brunei. Although overall genetic divergence between populations was low, two populations (Ingei and Labi Road 3) were distinct from the other populations. Analysis using DIYABC estimated that three genetic groups (Ingei, Labi Road 3 and others) diverged simultaneously from their ancestral population, whose effective size was very small, about 7,500 years ago, corresponding to a recent sea level peak in the Belait-Baram river basin. In that high sea level period, some higher-elevation lands remained, and peat formation had already started in this region. We propose that the current genetic structure of S. albida in Brunei was formed from small refugial populations that survived the period of higher sea level in these higher-elevation areas. Because of their relatively high genetic diversity, Brunei's S. albida populations should become an important genetic resource for the recovery of genetically healthy populations in other parts of northwest Borneo.

First evidence of a monodominant (Englerodendron, Amherstieae, Detarioideae, Leguminosae) tropical moist forest from the early Miocene (21.73 Ma) of Ethiopia.

Many tropical wet forests are species-rich and have relatively even species frequency distributions. But, dominance by a single canopy species can also occur in tropical wet climates and can remain stable for centuries. These are uncommon globally, with the African wet tropics supporting more such communities than the Neotropics or Southeast Asia. Differences in regional evolutionary histories are implied by biogeography: most of Africa's monodominance-forming species are Amherstieae-tribe legumes; monodominance in Neotropical forests occur among diverse taxonomic groups, often legumes, but rarely Amherstieae, and monodominance in Southeast Asian forests occurs mostly among Dipterocarpaceae species. African monodominant forests have been characterized ecologically and taxonomically, but their deep-time history is unknown despite their significant presence and bottom-up ecological influence on diversity. Herein we describe fossil leaflets of Englerodendron mulugetanum sp. nov., an extinct species of the extant genus Englerodendron (Berlinia Clade, Amherstieae, Detarioideae) from the 21.73 Ma Mush Valley site in Ethiopia. We also document a detailed study of associated legume pollen, which originate from a single taxon sharing characters with more than one extant descendant. Taxonomically, the pollen is most comparable to that from some extant Englerodendron species and supports a likely affiliation with the Englerodendron macrofossils. The Mush Valley site provides the first fossil evidence of a monodominant tropical forest in Africa as represented by leaflets and pollen. Previous studies documented >2400 leaves and leaflets from localities at six stratigraphic levels spanning 50,000-60,000 years of nearly continuous deposition within seven meters of section; all but the basal level contain ≥ 50% E. mulugetanum leaflets. Modern leaf litter studies in African mixed vs. monodominant forests indicates the likelihood of monodominance in the forests that surrounded the Mush paleolake, particularly after the basal level. Thus, we provide an early case for monodominance within the Amherstieae legumes in Africa.

Conservation of Forest, Based on a Fuelwood Substitute as Well as Considering the Cultural and Spiritual Values: An Optimal Fuelwood Harvest Model

Abstract Excessive fuelwood harvest is a major cause of deforestation in developing countries. To mitigate this, various preventive measures have been introduced in different countries. The availability of affordable substitutes to the community dependent on the forest for domestic energy consumption may prevent further forest degradation. A stock-dependent optimal control model of fuelwood harvest from a natural forest is presented here and comparative statics has been used to show that the presence of a fuelwood substitute will reduce its harvest and increase the forest stock. The model indicates that the availability of cheaper and high-energy content alternatives for fuelwood can substantially reduce fuelwood extraction from a forest. Also, a lower discount rate and higher cultural and spiritual values (CSV) will keep the optimal forest stock close to its carrying capacity and reduce fuelwood harvest. The model reveals that the maximum sustainable yield of forest stock and the ratio of energy content per unit mass of fuel plays a central role in the fate of forest stock and the level of fuelwood harvest. An empirical example of the Southeast Asian Forest growth model along with Liquid Petroleum Gas (LPG) as a substitute has been used to illustrate the results. The outcomes of this study can be incorporated into forest conservation policies.

Strengthened multi-stakeholder linkages in valuation studies is critical for improved decision making outcomes for valuable mangroves – The Malaysian case study

Mangrove forests in Southeast Asia are continuously declining as a result of unsustainable practices, partly due to limited recognition of the value of mangrove services in land use decision making. Valuation practitioners have assumed that monetary valuation should inform local and national decision makers to ensure sustainable management of mangrove resources. For ecosystem service valuation to be of use to decision makers, best practices should be adhered to such as having straightforward policy questions and strong stakeholder engagement from the onset of valuation studies, suitable choice of valuation methodologies, and the ability to effectively demonstrate causal links between drivers of ecosystem health, change, and resource users. This study, focusing on the Malaysian case study, assessed the effectiveness and challenges of local ecosystem service valuation studies in informing mangrove management decisions against a set of global best practices. A systematic review approach was undertaken to identify relevant Malaysian mangrove ecosystem service valuation studies. Of 184 studies identified, only 17 provided monetary values for mangrove ecosystem services. These studies valued nine different mangrove ecosystem services, with the cultural ecosystem services of tourism being the most frequently valued. Most of the valuation studies were designed to raise awareness of the value of ecosystems (64.7%). Other intended uses included determining appropriate charging rates for mangrove uses (17.6%), comparing the costs and benefits of different environmental uses (11.8%), and providing a justification and support for certain decision making (5.9%). Overall, mangrove valuation studies in Malaysia were characterized by weak multi-stakeholder engagement, non-standardized valuation units across the whole country, limited dissemination of the valuation outcome, and cursory references to the potential use of mangrove ecosystem services. Most of the studies did not exert apparent influence on mangrove management. Future valuation studies in Malaysia and the Southeast Asian region should aim to build more robust engagement between valuation practitioners and key stakeholder groups, especially decision makers, at all stages of the study process and incorporate a clear dissemination strategy for sharing results.

Implications of tropical cyclones on damage and potential recovery and restoration of logged forests in Vietnam.

Many natural forests in Southeast Asia are degraded following decades of logging. Restoration of these forests is delayed by ongoing logging and tropical cyclones, but the implications for recovery are largely uncertain. We analysed meteorological, satellite and forest inventory plot data to assess the effect of Typhoon Doksuri, a major tropical cyclone, on the forest landscapes of central Vietnam consisting of natural forests and plantations. We estimated the return period for a cyclone of this intensity to be 40 years. Plantations were almost twice as likely to suffer cyclone damage compared to natural forests. Logged natural forests (9-12 years after cessation of government-licensed logging) were surveyed before and after the storm with 2 years between measurements and remained a small biomass carbon sink (0.1 ± 0.3 Mg C ha-1 yr-1) over this period. The cyclone reduced the carbon sink of recovering natural forests by an average of 0.85 Mg C ha-1 yr-1, less than the carbon loss due to ongoing unlicensed logging. Restoration of forest landscapes in Southeast Asia requires a reduction in unlicensed logging and prevention of further conversion of degraded natural forests to plantations, particularly in landscapes prone to tropical cyclones where natural forests provide a resilient carbon sink. This article is part of the theme issue 'Understanding forest landscape restoration: reinforcing scientific foundations for the UN Decade on Ecosystem Restoration'.

Landscape‐scale drivers of liana load across a Southeast Asian forest canopy differ to the Neotropics

Abstract Lianas (woody vines) are a key component of tropical forests, known to reduce forest carbon storage and sequestration and to be increasing in abundance. Analysing how and why lianas are distributed in forest canopies at landscape scales will help us determine the mechanisms driving changes in lianas over time. This will improve our understanding of liana ecology and projections of tropical forest carbon storage now and into the future. Despite competing hypotheses on the mechanisms driving spatial patterning of lianas, few studies have integrated multiple tree‐level biotic and abiotic factors in an analytical framework. None have done so in the Palaeotropics, which are biogeographically and evolutionarily distinct from the Neotropics, where most research on lianas has been conducted. We used an unoccupied aerial system (UAS; drone) to assess liana load in 50‐ha of Palaeotropical forest canopy in Southeast Asia. We obtained data on hypothesised drivers of liana spatial distribution in the forest canopy, including disturbance, tree characteristics, soil chemistry and topography, from the UAS, from airborne LiDAR and from ground surveys. We integrated these in a comprehensive analytical framework to extract variables at an individual‐tree level and evaluated the relative strengths of the hypothesised drivers and their ability to predict liana distributions through boosted regression tree (BRT) modelling. Tree height and distance to canopy gaps were the two most important predictors of liana load, with relative contribution values in BRT models of 34.60%–45.39% and 7.93%–10.19%, respectively. Our results suggest that taller trees were less often and less heavily infested by lianas than shorter trees, opposite to Neotropical findings. Lianas also occurred more often, and to a greater extent, in tree crowns close to canopy gaps and to neighbouring trees with lianas in their crown. Synthesis. Despite their known importance and prevalence in tropical forests, lianas are not well understood, particularly in the Palaeotropics. Examining 2428 trees across 50‐ha of Palaeotropical forest canopy in Southeast Asia, we find support for the hypothesis that canopy gaps promote liana infestation. However, we also found that liana presence and load declined with tree height, which is opposite to well‐established Neotropical findings. This suggests a fundamental difference between Neotropical and Southeast Asian forests. Considering that most liana literature has focused on the Neotropics, this highlights the need for additional studies in other biogeographic regions to clarify potential differences and enable us to better understand liana impacts on tropical forest ecology, carbon storage and sequestration.

Impact of climate change on Southeast Asian natural habitats, with focus on protected areas

Natural habitats have been destroyed by anthropogenic factors for several decades, exacerbated by climate change. This study investigated the impact of climate change on natural habitats by using 55 Phasianidae species. We predicted current and future species distribution based on three climate change scenarios. We then (1) determined the effect of climate change on each species by comparing the distribution and elevation range shift between current and future predictions. In addition, we (2) estimated the total large habitat patches (> 40 km 2 ) for each species, and determine how it change in the future. We also (3) investigated large habitat patches change within PAs. Moreover, we (4) evaluated the Phasianidae diversity hotspots in the current and future predictions. The results showed climate change is likely to reduce the suitable natural habitats in Southeast Asia, with an average reduction of habitat patches was 180,970 km 2 (11%) when comparing the future predictions with the current state. Most of the species appeared to be retreating to higher altitudes and face suitable habitat reduction by 2100. The large habitat patch average declined 183,474 km 2 (12%), with 2–10 species in imminent danger of losing their habitat (depending on the climate change modeling scenarios). The current large patches in the protected areas represented a small proportion of the total large patch distribution, and there were fewer future large patches than currently available. The species risk a reduction in diversity, especially in the Indo-Burma region where most of them are facing a massive loss of their suitable habitats. We suggest the use of Phasianidae as indicator species to monitor natural forests in Southeast Asia and the implementation of adaptive conservation management to prevent further losses in the future.

Size‐dependent intraspecific variation in wood traits has little impact on aboveground carbon estimates in a tropical forest landscape

Abstract There is increasing evidence that intraspecific trait variation plays a role in governing rates of ecosystem functioning. While wood traits such as wood specific gravity (WSG) and wood carbon concentration (WCC) are key drivers of forest aboveground carbon (AGC) stocks, the sources of intraspecific variation in these wood traits and the consequences of this variation on AGC are poorly known, especially in the tropics. Here, we investigated intraspecific variation in wood specific gravity (WSG) and wood carbon concentration (WCC) from 556 individual trees belonging to 15 species that well characterize different successional stages of seasonal evergreen forests in Southeast Asia. Specifically, we tested the contribution of individual or species characteristics (tree size, growth rate and regeneration guilds) and local environmental conditions (topographic wetness index and successional stages) to intraspecific variation in WSG and WCC, and assessed the consequences of intraspecific variation in these wood traits on AGC estimates in 14 permanent forest plots established along a successional gradient in Khao Yai National park, Thailand. We found that tree size was the main driver of intraspecific variation in WSG and WCC as tree sizes increased from 10–100 cm in diameter, WSG increased by 7.3%, while WCC increased by 2.4% in heartwood, 1.6% and 2.7% in sapwood without and with volatile carbon included. There was no effect of the topographic wetness and other local environment condition in wood traits led to a slight overestimation of AGC in young secondary forests (+0.09% to +1.29%) and a small underestimation in older forests (−0.86% to −2.87%), but overall AGC estimates (13 of 14 forest plots) remained within error margins (the 95% interval). Our study provides evidence that tree size variation translates into intraspecific variability in wood traits, whereas local environmental conditions related to topography successional stages had no effect on wood trait variability. While size‐dependent variation in WSG and WCC have largely been undocumented and thus ignored in forest carbon assessment approaches, we highlight that it has a limited impact on AGC estimates, indicating that it does not invalidate current forest carbon stock estimation approaches. Read the free Plain Language Summary for this article on the Journal blog.

Quantifying transportation infrastructure pressure on Southeast Asian World Heritage forests

Transportation infrastructure has expanded rapidly in Southeast Asian forests over the last 20 years, opening up remote areas to the degrading effects of internal forest fragmentation and human exploitation. Natural World Heritage sites (NWHS) can be a powerful policy instrument to safeguard tropical forest ecosystems (when adequately implemented and enforced, and communicated to all relevant stakeholders); however, despite this mechanism, transportation infrastructure pressure has been increasing in NWHS forests. Here we propose a novel GIS approach to assess spatial and temporal changes in transportation infrastructure pressure on NWHS in Southeast Asia using a Transportation Infrastructure Pressure Index (TIPI) and forest fragmentation analysis, underpinned by global open-source datasets. Mean pressure in Southeast Asian NWHS is lower than in their surrounding areas (15 km), suggesting that NWHS protection is preventing some deterioration. However, in the last 5 years, these sites have also come under increasing transportation infrastructure pressure (at a mean rate of 14.9% over the period 2014–2019 across 12 sites in Southeast Asia). Furthermore, increases in transportation pressure in NWHS surrounding areas are correlated with increases in transportation pressure inside NWHS. With transportation infrastructure projected to continue to expand globally, GIS-based analysis methods such as these could enhance existing NWHS monitoring efforts, providing early warning about pressures that may be contributing to forest degradation and biodiversity declines in NWHS.