Tropical Montane Forest Research Articles

Microsite Preferences and Determinants for Recruitment of Keystone Tree Species in a Tropical Montane Forest of Myanmar

ABSTRACT Successful plant recruitment is crucial for maintaining forest ecosystems, but knowledge of the responses of early life stages of tropical montane tree species to complex environmental factors is still limited across the Himalayas. Vegetation was surveyed along an altitudinal gradient (2450–3070 m) in six altitudinal bands in a tropical montane forest of Myanmar. We examined the effects of microclimate, soil, and microsite conditions on seedling and sapling recruitment in three dominant tree species (Quercus semecarpifolia, Rhododendron arboreum, and Symplocos lucida). We found that densities of R. arboreum and Q. semecarpifolia were higher in high and mid-altitudinal bands (2800–3000 m), whereas density of S. lucida was higher in lower altitudinal bands (2600–2700 m). Seedlings showed better recruitment in humid conditions and more sensitive to soil properties than saplings. R. arboreum and S. lucida preferred debris microsites, followed by shrub and grass microsites, whereas Q. semecarpifolia showed no significant microsite preference. Seedling recruitment mainly depended on soils and microsites, whereas sapling recruitment depended on microclimate and altitude. The study provides information on species-specific preferences and responses of montane tree species to complex environmental factors, which may contribute to restoration and sustainable forest conservation.

Deforestation Impacts on Orographic Precipitation in the Tropical Andes

This study examines the implications of Tropical Montane Forests (TMFs) loss on orographic precipitation in the Eastern slopes of the Andes (EADS). The focus is on moist processes for synoptic regimes associated with significant EADS precipitation: (1) monsoon rainfall for weak and strong South America Low-Level Jet (LLJ) conditions and (2) heavy rainfall associated with cold air intrusions (CAI) in the dry season. High-resolution simulations using the Weather Research and Forecasting (WRF) model were conducted for realistic and modified land-cover resulting from the conversion of TMFs to savanna. The deforestation scenarios result in 50–100% decrease (up to ∼400 J kg–1) in Convective Available Potential Energy (CAPE) spatially organized by land-cover change along the EADS. Analysis of the differences in simulated frequency distributions of rainfall intensity shows robust daytime increases in light rainfall (<2 mm h–1) and decreases in moderate rainfall rates (2–10 mm h–1) in the altitudinal band 500–2,000 m where orographic enhancement is dominant. Whereas there are negligible changes in the spatial patterns of precipitation and hydrologic response for monsoon conditions, rainfall accumulations decrease for all cases, and the precipitation maxima shift downslope into the Amazon lowlands. Changes in rainfall amount and intensity result in runoff decreases of 5–10% at the event-scale for the CAI case. Sensitivity simulations for lower initial soil moisture conditions indicate a strong positive feedback of forest loss to hydrologic drought along the EADS foothills in the austral spring when CAIs play a key role in the tropical EADS dry season hydrometeorology.

Can small-scale altitudinal gradients predict spatial and temporal patterns in tropical forests?

In tropical montane forests, compositional and structural changes are commonly driven by broad-scale altitudinal variation. Here, given the lack of knowledge on small-scale vegetation changes and temporal dynamics, we address the effects of small-scale variations in soil and altitude on tree community structure, temporal dynamics and phylogenetic diversity in a semi-deciduous tropical forest of the Atlantic Forest Domain, southeastern Brazil. In 2010 and 2015 we sampled thirty plots of 400 m2, set up along an altitudinal gradient between 1000 and 1500 m a.s.l.. In each plot, we collected soil samples for chemical and textural analyses. We fitted linear models to test the effects of altitude and soil on community dynamics and phylogenetic parameters. Altitude and soil explained the spatial variation in number of individuals and phylogenetic diversity metrics. From lower to higher altitudes, we found decreasing fertility, increasing tree density and decreasing phylogenetic diversity. Altitude significantly influenced the increases in total biomass (from 240.9 to 255.4 t ha−1) and individual biomass (from 0.15 to 0.17 t) recorded in the interval. And while community temporal dynamics had rates of 1.96% for mortality, 1.02% for recruitment, 1.61% for biomass loss and 2.81% for biomass gain, none of them were explained by altitude or soil. Temporal species substitution averaged 0.1 in the interval. Altogether, these results suggest that the small-scale variations in altitude and soil likely determine the conditions and resources that drive community assembly and structure, which are expressed by spatial variations along the altitudinal gradient. At the same time, temporal patterns were not influenced by altitude-related environmental variation, resulting in a similar dynamic behaviour across the gradient, suggesting that broad-scale factors may play a more important role than local ones.

Effects of biotic/abiotic factors on the seedling regeneration of Dacrydium pectinatum formations in tropical montane forests on Hainan Island, China

Exploring natural regeneration facilitates a better understanding of the mechanisms of community assembly and biodiversity formation. However, convincing data on tree regeneration in threatened tropical plant communities are lacking. Dacrydium pectinatum is a constructive and endangered species in tropical montane forests of Hainan Island. This study aims to identify the seedling regeneration patterns of D. pectinatum formation and their key drivers. A total of 204 seedling plots were investigated in the northwest (Bawangling, 90 plots), southwest (Jianfengling, 90 plots) and southeast (Diaoluoshan, 24 plots) of Hainan Island. We examined the variations in the seedling/adult composition, density and richness along local scales and elevation gradients and analyzed the relationships between biotic/abiotic variables and seedling regeneration. The seedling distribution pattern changed with environmental gradients, and the seedling density and richness decreased from low to high latitudes and from low to high elevations. Additionally, the adult density and total base area also showed consistent trends. At the community and species levels, the biotic neighborhood variables had a primary impact on the seedling density and richness. Multiple environmental factors (such as the canopy density, elevation, slope, soil organic matter, and soil total nitrogen) also showed significant correlations with the seedling density and richness. Our study supports conspecific negative density dependence and niche filtering as the general mechanisms of natural regeneration of D. pectinatum formations. Both biotic and abiotic factors might affect the survival and growth of seedlings, and their relative importance varies with environmental gradients and species. We conclude that enclosing forests with moderate stand densities in low-elevation areas to reduce human interference will help optimize the community structure. However, for high-elevation areas and high-density forests, appropriate thinning, manual regeneration and open gaps are needed to improve the light environment and soil nutrients, thereby promoting the natural regeneration of D. pectinatum formations.

Modification of Fire Regimes Inferred from the Age Structure of Two Conifer Species in a Tropical Montane Forest, Mexico

Research Highlights: Age structure was used to infer fire regimes in the Monarch Butterfly Biosphere Reserve. Uneven-aged structures in stands dominated and co-dominated by pine and fir species, which are distributed according to an altitudinal gradient, indicated a regime of frequent, low-severity, and low-intensity fires. Background and Objectives: Age structure analyses have been used to infer natural and disrupted fire regimes when field-based descriptions of fires are scarce or unavailable. In montane conifer forests, fire regimes typically vary according to an altitudinal gradient, shaping contrasting tree establishment patterns. In the Monarch Butterfly Biosphere Reserve, Mexico, the altitudinal distribution and fire regimes of sacred fir forests (Abies religiosa), smooth-bark Mexican pine forests (Pinus pseudostrobus), and mixed-conifer forests are poorly documented. The objectives of this study were to determine the altitudinal ranges occupied by mono-dominant and co-dominant stands and to reconstruct tree establishment history to infer historical fire regimes. Materials and Methods: Six altitudinal transects were established along the reserve, each one at elevations from 2400 to 3300 m, with sampling sites at every 150 m of elevation. In each site, increment cores were collected from the base of 25 mature trees. A total of 800 increment cores were collected and cross-dated. Results: P. pseudostrobus is dominant in stands between 2400 and 2850 m, A. religiosa between 3150 and 3300 m, and both species co-dominate between 2850 and 3150 m. The establishment pattern for both species has been continuous, represented by uneven-aged structures, suggesting that tree establishment in smooth-bark Mexican pine forests, mixed-conifer forests, and sacred fir forests, is likely to be associated with frequent, low-severity, and low-intensity fires. Conclusions: These fire regimes suggest, by the one hand, the disruption of natural fire regimes by human activities, limiting the occurrence of high-severity fires; on the other hand, a distinctive feature of these tropical montane forests.

Aboveground Biomass Changes in Tropical Montane Forest of Northern Borneo Estimated Using Spaceborne and Airborne Digital Elevation Data

Monitoring anthropogenic disturbances on aboveground biomass (AGB) of tropical montane forests is crucial, but challenging, due to a lack of historical AGB information. We examined the use of spaceborne (Shuttle Radar Topographic Mission Digital Elevation Model (SRTM) digital surface model (DSM)) and airborne (Light Detection and Ranging (LiDAR)) digital elevation data to estimate tropical montane forest AGB changes in northern Borneo between 2000 and 2012. LiDAR canopy height model (CHM) mean values were used to calibrate SRTM CHM in different pixel resolutions (1, 5, 10, and 30 m). Regression analyses between field AGB of 2012 and LiDAR CHM means at different resolutions identified the LiDAR CHM mean at 1 m resolution as the best model (modeling efficiency = 0.798; relative root mean square error = 25.81%). Using the multitemporal AGB maps, the overall mean AGB decrease was estimated at 390.50 Mg/ha, but AGB removal up to 673.30 Mg/ha was estimated in the managed forests due to timber extraction. Over the 12 years, the AGB accumulated at a rate of 10.44 Mg/ha/yr, which was attributed to natural regeneration. The annual rate in the village area was 8.31 Mg/ha/yr, which was almost 20% lower than in the managed forests (10.21 Mg/ha/yr). This study identified forestry land use, especially commercial logging, as the main driver for the AGB changes in the montane forest. As SRTM DSM data are freely available, this approach can be used to estimate baseline historical AGB information for monitoring forest AGB changes in other tropical regions.

Evolutionary heritage shapes tree distributions along an Amazon‐to‐Andes elevation gradient

AbstractUnderstanding how evolutionary constraints shape the elevational distributions of tree lineages provides valuable insight into the future of tropical montane forests under global change. With narrow elevational ranges, high taxonomic turnover, frequent habitat specialization, and exceptional levels of endemism, tropical montane forests and trees are predicted to be highly sensitive to environmental change. Using plot census data from a gradient traversing > 3,000 m in elevation on the Amazonian flank of the Peruvian Andes, we employ phylogenetic approaches to assess the influence of evolutionary heritage on distribution trends of trees at the genus‐level. We find that closely related lineages tend to occur at similar mean elevations, with sister genera pairs occurring a mean 254 m in elevation closer to each other than the mean elevational difference between non‐sister genera pairs. We also demonstrate phylogenetic clustering both above and below 1,750 m a.s.l, corresponding roughly to the cloud‐base ecotone. Belying these general trends, some lineages occur across many different elevations. However, these highly plastic lineages are not phylogenetically clustered. Overall, our findings suggest that tropical montane forests are home to unique tree lineage diversity, constrained by their evolutionary heritage and vulnerable to substantial losses under environmental changes, such as rising temperatures or an upward shift of the cloud‐base.

Total organic carbon concentrations in ecosystem solutions of a remote tropical montane forest respond to global environmental change

The response of organic carbon (C) concentrations in ecosystem solutions to environmental change affects the release of dissolved organic matter (DOM) from forests to surface and groundwaters. We determined the total organic C (TOC) concentrations (filtered <1-7µm) and the ratios of TOC/dissolved organic nitrogen (DON) concentrations, electrical conductivity (EC), and pH in all major ecosystem solutions of a tropical montane forest from 1998 to 2013. The forest was located on the rim of the Amazon basin in Ecuador and experienced increasing numbers of days with >25°C, decreasing soil moisture, and rising nitrogen (N) deposition from the atmosphere during the study period. In rainfall, throughfall, mineral soil solutions (at the 0.15- and 0.30-m depths), and streamflow, TOC concentrations and fluxes decreased significantly from 1998 to 2013, while they increased in stemflow. TOC/DON ratios decreased significantly in rainfall, throughfall, soil solution at the 0.15-m depth, and streamflow. Based on Δ14 C values, the TOC in rainfall and mineral soil solutions was 1year old and that of litter leachate was 10years old. The pH in litter leachate decreased with time, that in mineral soil solutions increased, while those in the other ecosystem solutions did not change. Thus, reduced TOC solubility because of lower pH values cannot explain the negative trends in TOC concentrations in most ecosystem solutions. The increasing TOC concentrations and EC in stemflow pointed at an increased leaching of TOC and other ions from the bark. Our results suggest an accelerated degradation of DOM, particularly of young DOM, associated with the production of N-rich compounds simultaneously to changing climatic conditions and increasing N availability. Thus, environmental change increased the CO2 release to the atmosphere but reduced DOM export to surface and groundwater.

Effect of forest succession and microenvironmental variables on the abundance of two wandering spider species (Araneae: Ctenidae) in a montane tropical forest

This study assessed the effects of forest succession and microenvironmental variables on the abundance of ctenid spiders in a montane tropical forest in Costa Rica. We surveyed 20 plots (5 × 5 m) in both primary and secondary forest for a total of 40 samples measuring the following variables: leaf litter depth, canopy density, slope, number of trees above 3 m and average stem diameter of trees exceeding 3 m in height. A total of 150 adult and subadult specimens belonging to five species were observed. The most abundant species were Spinoctenus escalereteHazzi et al., 2018 which has not previously been recorded in Central America and Kiekie griswoldiPolotow & Brescovit, 2018. The larger species, K. griswoldi was significantly more abundant in primary than in secondary forest. Conversely, S. escalerete was more abundant in the secondary forest. A generalized linear model indicated that the most important variable influencing ctenids abundance was leaf litter depth. Whereas the abundance of K. griswoldi was positively related with leaf litter depth, the abundance of S. escalerete was negatively related to litter depth. Thus, forest succession and leaf litter are important factors that influence the abundance of floor ctenid community and may allow the coexistence of co-occurring species.

Tropical Montane Forest Conversion Is a Critical Driver for Sediment Supply in East African Catchments

AbstractLand use change is known to affect suspended sediment fluxes in headwater catchments. There is however limited empirical evidence of the magnitude of these effects for montane catchments in East Africa. We collected a unique 4‐year high‐frequency data set and assessed seasonal sediment variation, water pathways, and sediment response to hydrology in three catchments under contrasting land use in the Mau Forest Complex, Kenya's largest tropical montane forest. Annual suspended sediment yield was significantly higher in a smallholder agriculture‐dominated catchment (131.5 ± 90.6 t km−2 yr−1) than in a tea‐tree plantation catchment (42.0 ± 21.0 t km−2 yr−1) and a natural forest catchment (21.5 ± 11.1 t km−2 yr−1) (p &lt; 0.05). Transfer function models showed that in the natural forest and the tea‐tree plantations subsurface flow pathways delivered water to the stream, while in the smallholder agriculture shallow subsurface and surface runoff were dominant. There was a delayed sediment response to rainfall for the smallholder agriculture and the tea‐tree plantations. A slow depletion in sediment supply suggests that the wider catchment area supplies sediment, especially in the catchment dominated by smallholder farming. In contrast, a fast sediment response and depletion in sediment supply in the natural forest suggests a dominance of temporarily stored and nearby sediment sources. This study shows that the vegetation cover of a forest ecosystem is very effective in conserving soil, whereas catchments with more bare soil and poor soil conservation practices generated six times more suspended sediment yield. Catchment connectivity through unpaved tracks is thought to be the main explanation for the difference in sediment yield.

Topography, drainage capability, and legacy of drought differentiate tropical ecosystem response to and recovery from major hurricanes

High-carbon sequestrations of tropical montane forests and coastal mangroves have been greatly disturbed by intensified extreme climate events such as alternating hurricanes and droughts. However, few studies of the hurricane impact have taken into consideration the legacy of past climate events and analyzed the heterogeneity of hurricane impacts between montane forests and coastal mangroves. Here, we studied the impact of Hurricanes Irma and Maria in 2017 on coastal mangroves and upland forests in Puerto Rico after a severe drought during 2015–2016. We investigated the island-wide immediate impact on greenness using fused vegetation index from Sentinel-2 and Landsat-8, and the impact on and the recovery of 62 homogeneous vegetation patches by deriving an impact index and one-year recovery ratio (RR). A linear mixed-effect model was applied to explore roles of hurricane wind, rainfall, topography, and biological components in the impact and the recovery. Island-wide, the immediate impact is highly spatial-heterogeneous. Although most of the island was browned, a green-up strip in the dry south showed benefits from the hurricane rain which relieved the prior drought stress. Coastal mangroves experienced the greatest impact and slowest recovery with relative recovery of 0.44 compared to recovery greater than 0.70 for upland forests, and evergreen forests sustained significantly more damage than deciduous forests. The recovery of evergreen forests was on average 11 days earlier and faster than that of mangroves. Mangrove recovery was mostly limited by inundation-related factors such as elevation, slope, and drainage capacity. While higher elevation relates to slower recovery for upland forests, it favors mangrove recovery. Particularly, mangrove recovery is facilitated by river presence, explaining 65% variation in RR. The differentiated response, recovery, and underlying mechanisms highlighted a complicated array of external forces, geophysical/ biological modulators, and legacy of past climate events in determining and understanding hurricanes’ impact on tropical ecosystems.

Compositional variation in understorey fern and palm communities along a soil fertility and rainfall gradient in a lower montane tropical forest

AbstractQuestionsFerns and palms are key components of tropical wet forest understories. The distributions of these groups are influenced by variation in rainfall and soil properties, although the degree to which their resource requirements overlap remains unclear. Palms and ferns also represent extremes in a spectrum of reproductive traits, which may impact habitat requirements and compositional turnover. We asked whether: (a) environmental variables influence fern and palm distributions in a similar manner across a gradient in soil nutrient availability; and (b) larger propagule size and lower reproductive output in palms result in greater spatial aggregation of populations and, consequently, greater distance–decay rates in community similarity in palms than ferns.LocationOld‐growth premontane forest, Fortuna, western Panama.MethodsAll ferns and palms were sampled in fifteen 5 m × 5 m subplots in each of 12 one‐hectare plots. The plots span a strong gradient in soil nutrient availability related to parent material. Light, precipitation and soil variables were measured in each subplot. Species associations were analyzed using ordination and regression, as well as Procrustes and Mantel tests.ResultsParent material significantly impacted compositional similarity of both ferns and palms, with fern compositional variation related to total soil N:P ratio and red:far red (R:FR), and palms with bulk density (p &lt; 0.05). Palm and fern abundances were not correlated; however, tree fern abundances showed an opposing abundance relationship with total soil N:P and R:FR compared to herbaceous ferns and palms. Distance–decay rates in compositional similarity were slightly higher for palms than ferns.ConclusionsFerns and palms show similar patterns of compositional variation in response to resource availability but were related to distinct environmental factors. Soil fertility and light availability emerged as key factors in predicting the abundance of plant groups, with clear partitioning of environmental gradients only apparent when tree ferns were compared with other groups.

Redescription of the snake Lachesis melanocephala (Squamata: Viperidae): Designation of a neotype, natural history, and conservation status

Introduction: The Black-headed Bushmaster (Lachesis melanocephala) is a large venomous snake that inhabits tropical moist forest, wet forest, montane and premontane wet forest in Southwestern Costa Rica and extreme Western Panama. Objective: We assign a neotype for the species due to the loss of the original holotype and update the information on its geographical distribution, natural history, and conservation status. Methods: To determine the conservation status of L. melanocephala, we modeled its potential distribution using the species` locality records and distribution modeling analysis implemented in MaxEnt. Based on the species’ potential distribution, we evaluate the loss of its original habitat and estimate the percentage of its distribution area that is currently protected by the country’s protected area system. Results: The potential distribution of the species was estimated at 10 139 km2, including areas where the species currently occurs and historical areas where the species has been registered but is nowadays considered locally extinct. About 29 % of that potential distribution overlaps with protected wild areas, so less than a third of the potential distribution of the species is under protection. Conclusions: During the last decade, accelerated habitat loss and growing evidence of declining natural populations indicate the need for urgent protective measures to prevent the extinction of this species in the foreseeable future.

Daily tayra (Eira barbara, Linnaeus 1758) activity patterns and habitat use in high montane tropical forests

Activity patterns and habitat use are important for understanding the natural history of a species and its ecology. Some species of carnivore are abundant, but little studied, such as the tayra (Eira barbara). In this context, the activity patterns and environmental factors that influence tayra frequency of occurrence in high montane tropical rainforests in the Atlantic Rainforest biome were evaluated. A total of 32 points distributed in the Itatiaia National Park and the Alto Montana Natural Heritage Reserve were investigated for three years, in a gradient ranging from 800 to 2200 m elevation. Tayra frequency of occurrence was evaluated using camera traps and environmental variables were obtained. Photo time data indicate that tayra are predominantly diurnal and their frequency of occurrence is higher at lower elevations and in areas more distant from human habitation. Although this species occurs at all elevation, the tayra may prefer lower elevation habitats, due to the higher productivity of these areas compared to higher elevational environments. The results reported herein contribute to a better knowledge of the species and may aid in planning models and conservation actions for ecological function and tropical biodiversity maintenance.

DIVERSITY AND ECOLOGY OF LAND SNAILS IN GUNUNG HALIMUN SALAK NATIONAL PARK (GHSNP) IN JAVA, INDONESIA

The land snail fauna of the largest tropical montane forest in Java, the Gunung Halimun Salak National Park (GHSNP), was surveyed during the dry season (June-July) in 2015, concentrating on four park’s resorts, i.e. Cikaniki, Mt. Botol, Cisarua (Halimun area) and Cidahu (Salak area). In total, 399 specimens representing 43 species were collected. Prior to the surveys, 48 land snail species were known from the GHSNP. Fifteen new records for the GHSNP were discovered so 63 species are now known to inhabit the Park. This number represent 25% of the total land snail fauna of Java. 21 of the species found in GHSNP are endemic to Java. The species richness of the plots in GHSNP was correlated with soil pH and the composition of the land snail communities was correlated with elevation, annual mean temperature, and amount of deadwood.

Fine root-arbuscular mycorrhizal fungi interaction in Tropical Montane Forests: Effects of cover modifications and season

Tropical Montane Forests are unique climate-influenced ecosystems with a vital role for some ecosystem services, of which one of the most important is soil carbon storage. Changes in forest cover affect forest structure, composition and functioning, but little is known about how such changes influence the belowground carbon content. In this study, we addressed this issue by evaluating whether fine-root production differed between forest-cover types and contrasting seasons after controlling arbuscular mycorrhizal fungi (AMF) traits, and what the minimum time required to detect such differences is. We also determined whether AMF-related traits were affected by distinct forest cover and seasons after controlling fine-root production. The objects of study were four forests with distinct degradation histories in the Atlantic Forest: Old-growth, Post-selective logging, Post-clear-cut and Post-pasture forests. Data were collected in four 2500-m2 plots installed in each area and analyzed through multivariate statistics. Fine-root production differed significantly between forest covers, and marginally between seasons, as it was greater in the post-pasture area and in the rainy season. Some AMF traits also differed between forest covers and seasons, especially the abundance of viable spores in the dry season. We found that the shortest period necessary to identify differences in the production of fine roots was over three months. This study shows that forests with different degradation histories and annual climatic variations significantly affect fine-root production and AMF dynamics in Tropical Montane Forests. In particular, ecosystems that have been more perturbed tend to invest more in fine-root production (post-pasture). Our results help to better understand belowground interactions and biomass investment under different managed ecosystems.

Light and nutrient limitations for tree growth on young versus old soils in a Bornean tropical montane forest

We examined forest and tree responses to decreasing nutrient availability with soil aging in a species-rich tropical montane rain forest on Mount Kinabalu, Borneo. Community composition and structure and tree growth rates were compared between two 1 ha plots on nutrient-rich young soil versus nutrient-deficient old soil. Myrtaceae and Fagaceae dominated both plots. With soil aging, the dominance of Lauraceae, stem density, basal area and aboveground biomass decreased, and the forest understory became brighter. Some dominant taxa on the old soil (Podocarpaceae and the genus Tristaniopsis in Myrtaceae) were virtually absent on the young soil; this was attributed to light limitation in the understory. Growth rates of understory trees were lower on the young soil, whereas those of canopy trees were lower on the old soil. This suggested that the growth of understory trees was limited by light on the young soil, whereas that of canopy trees was limited by nutrients on the old soil. Of the eight species that were abundant in both plots, the dominance of five species was considerably lower on the old soil, four of which also exhibited decreased maximum sizes and lower growth rates. The remaining three species showed similar dominance across plots without a decline in growth rates, although they exhibited decreased maximum sizes on the old soil. These analyses demonstrated divergent responses of species to the soil-age gradient. We suggest that the differential responses of species to decreasing nutrient availability with a concomitant increase in understory light levels explain floristic turnover with soil aging.

Predation on Multiple Prey Types Across a Disturbance Gradient in Tropical Montane Forests of Peninsular Malaysia

Predation plays a critical role in animal and plant survivorship, and can be highly sensitive to habitat loss and disturbance. Tropical montane forests in Southeast Asia are being modified rapidly by land-use change, and the consequences of this on predation likelihood are poorly understood. In Peninsular Malaysia, we conducted predation experiments at eight tropical montane forest sites along a disturbance gradient. We investigated whether (1) predation pressure in primary forests differs between different mountains; (2) predation probability is linked to habitat degradation; and (3) vegetation variables explain predation occurrence. At each forest site, we placed artificial nests with real and model quail eggs, dishes with real and artificial seeds of the cempedak (Artocarpus champeden), models resembling four-lined tree frogs (Polypedetes leucomystax) and models of the late instar caterpillar of the common Mormon (Papilio polytes) at points 100 m apart for three nights. Using Bayesian binomial simulations, we showed that predation likelihood in primary forests from different mountains can vary (e.g., probability of the difference in predation rate of artificial caterpillars between two primary forests was estimated at 82%–100%). We also found that higher predation was not linked to habitat degradation for all artificial prey and seeds (e.g., comparing forests of varying degrees of disturbance from the same mountain, the probability that predation of an artificial caterpillar is lower at the primary forest was estimated at 2%–20% only). Model selection and hierarchical partitioning showed that vegetation variables can explain predation occurrence, suggesting microhabitat characteristics may be influential. Conducting predation experiments by using artificial prey and seeds is useful for comparing predation likelihood at different sites, making ecological comparisons, and for informing conservation decisions. This novel approach of using multiple prey items also showed that predation for each can vary and thus caution against deploying a single prey type to draw broad inferences of predation in degraded systems.

A New Species of the Genus Zhangixalus (Amphibia: Rhacophoridae) from Vietnam

We describe a new species of the genus Zhangixalus Li, Jiang, Ren &amp; Jiang, 2019 from Ha Giang Province, Vietnam based on morphological and molecular data. In the molecular phylogenetic analyses, the new species is nested in the Zhangixalus duboisi (Ohler, Marquis, Swan &amp; Grosjean, 2000) group, where it is sister to Z. duboisi with a genetic distance of 2.51%. The new species, Zhangixalus franki sp. nov., differs from its congeners by a combination of the following morphological characters: size large, SVL 77.9–85.8 mm in males; finger webbing formula I1-1II0-1III½-0IV; dorsal surface of head and body green with dark brown spots; ventral surface grey or dark grey, white stripe along edge of jaw, insertion of limbs, and along lateral ridges of fore and hind limbs and flank, separating upper green part from lower grey part. The new species occurs in evergreen montane tropical forests at an elevation of ca 1300 m a.s.l. The new discovery brings the total number of known species in the genus Zhangixalus to 38 and the species number reported from Vietnam to nine.

Evaluation of allometries for estimating above-ground biomass using airborne LiDAR data in tropical montane forest of Northern Borneo

Tropical forests play a crucial component of the terrestrial carbon pool and estimate of above-ground biomass (AGB) with high accuracy is important in quantifying tropical forest carbon stocks. There are several allometries available for estimating tropical forest tree AGB using field measurements, the choice of allometric equation is a decisive factor that can influence the AGB estimation accuracy. This study examined the use of allometric equations to accurately estimate AGB using airborne LiDAR data. The LiDAR data of Ulu Padas area was acquired using Optech Orion C200. 56 field plots were established to collect data on diameter at breast height, tree height and tree species. Field AGB was calculated from allometric equations of Yamakura et al. (1986), Basuki et al. (2009), Chave et al. (2005) and Chave et al. (2014). All LiDAR-derived height metrics and variables were correlated with field AGB (R: 0.30-0.88). Based on stepwise multiple regression analysis, Chave et al. (2014) allometry had highest model R2, explaining 81% of the variance of the field AGB. In short, allometry that includes wood density should be used in LiDAR applications on tropical forest AGB estimation.