Tropical Rainforest In Xishuangbanna Research Articles

Construction of the Ecological Security Pattern in Xishuangbanna Tropical Rainforest Based on Circuit Theory

Urban modernization and economic globalization have led to significant changes in traditional natural landscapes. The unregulated and large-scale expansion of rubber plantations in Xishuangbanna has resulted in water and scenic forests being replaced by rubber forests and the complex rainforest ecosystem being replaced by simple artificial forests. This has resulted in increasingly prominent ecological problems such as soil erosion, regional microclimate changes, and sharp declines in biodiversity. The ecological security pattern is an important way to protect regional ecological sustainability. Taking the tropical rainforest in Xishuangbanna as an example, this study identified ecological sources through the evaluation of the importance of ecosystem services, constructed resistance surfaces through ecological sensitivity evaluation, and used circuit theory to simulate ecological processes in heterogeneous landscapes by calculating “electricity” or “resistance”, thereby identifying ecological corridors and key ecological nodes. The results identified 31 ecological source areas, 65 key ecological corridors, 7 potential ecological corridors, 37 ecological pinch points, and 99 ecological barriers. The overall distribution of ecological sources was scattered, with higher density in the northwest and southeast regions. Ecological corridors were distributed along high mountains, and both ecological sources and corridors were mainly composed of forest land. Based on circuit theory, this study filled the gap in the MCR model’s inability to identify the true width of corridors due to ignoring the randomness of biological migration. It determined the spatial range of ecological corridors and the specific locations of ecological nodes and barriers, providing a reference for solving ecological problems in Xishuangbanna, such as “rainforest fragmentation”.

A dataset of soil moisture in Xishuangbanna tropical seasonal rain forests (2009–2017)

As the carrier of material circulation and energy flow, soil moisture plays an important role in terrestrial forest ecosystems. Observing soil moisture is beneficial for unveiling the hydrological characteristics, water conservation capacity and ecosystem service function of forest ecosystems. The tropical rain forest is among the most biodiverse ecosystems. There are large areas of tropical rain forests in Xishuangbanna, where the tropical seasonal rain forest represents a prominent vegetation type. Conducting continuous, long-term and high-quality ecological monitoring is one of the main tasks of China Ecosystem Research Network (CERN). Soil moisture content is an important indicator in the long-term site-specific water environment observations within the terrestrial ecosystems monitored by CERN. This dataset comprises soil moisture content data collected from January 2009 to December 2017 at the Xishuangbanna Station for Tropical Rainforest Ecosystem Studies of the Chinese Academy Sciences (also known as National Forest Ecosystem Research Station at Xishuangbanna, BNF for short), with a total of 2,879 entries. The determination method used for this dataset is fixed-point continuous observation using Time Domain Reflectometry (TDR) instruments; observations were conducted at multiple, ranging from 0–10 cm, 10–20 cm, 20–30 cm, 30–40 cm, 40–50 cm, 50–70 cm, 70–90 cm and 90–110 cm. The observation frequency consists of 3 times per month, respectively at the beginning, middle and end of each month. The observations were conducted strictly according to the CERN observation and quality control protocols. The dataset is readily available for online sharing and serves as essential foundational data for conducting research on tropical forest hydrology under the global climate change and different vegetation environments.

A dataset of soil carbon flux in Xishuangbanna tropical rainforest ecosystem from 2003 to 2008

Long-term and large-scale carbon flux data supports research on key processes of the global carbon and water cycle. Soil is the largest carbon pool in the terrestrial ecosystem. Small variations in soil carbon can significantly impact the carbon budgets of terrestrial ecosystems. Tropical forest is a crucial carbon sink in the world. However, there have been some reports indicating a decrease in soli carbon levels, potentially approaching neutrality, as a result of soil carbon degradation caused by global changing. Thus, the long-term and continuous observation of soil carbon flux is of great significance for evaluating the role of soil carbon in the tropical carbon cycle. ChinaFLUX Observation and Research Network (ChinaFLUX) has not only conducted the observation and research on carbon flux by using vorticity correlation technology, but also carried out the long-term observation and research on surface CO2 flux by using the box method. In this dataset, we collected and sorted out the soil CO2 emission flux data and conventional meteorological data of Xishuangbanna tropical rain forest ecosystem from January 2003 to August 2008 according to the static box observation method and data quality control management of greenhouse gas emissions. The dataset consists of three types of files at daily, monthly and yearly scales, covering surface CO2 flux, pressure, atmospheric temperature, soil temperature (5 cm) and soil water content (5 cm). It is expected to provide essential data for estimating carbon balance and understanding carbon cycle processes at both tropical and global scales.

Observed decreasing trend in pan evaporation in a tropical rainforest region during 1959–2021

Abstract Pan evaporation (Epan) is a critical measure of the atmospheric evaporation demand. Analyzing meteorological data from the Tropical Rainforest Comprehensive Meteorological Observation Field in the Xishuangbanna Tropical Botanical Garden (XTBG Meteorological Observing Station) based on physical models is helpful to improve our understanding of the state of the hydrological cycle in the Xishuangbanna tropical rainforest region. In this study, we investigated the long-term trend in Epan using the observation data from 1959 to 2021. Moreover, correlation analyses of Epan were performed, such as trend test, assessment of periodic properties and abrupt change analysis. Then, D20 Epan data and related meteorological data from 1979 to 2008 were used to drive Penman‒Monteith and PenPan models for simulating Epan. The partial derivative attribution method was used to analyze the dominant factors affecting Epan. The results showed that Epan exhibits obvious periodic changes, the 19a is the first primary period. In addition, there was a clear ‘evaporation paradox’ phenomenon in Xishuangbanna. Epan showed a decreasing trend during both 1959–2008 and 2009–2018, and the decreasing trend reached a significant level with a rate of −3.404 mm·a−2 during 1959–2008. Through comparative analysis, the PenPan model was considered more suitable for simulating Epan in Xishuangbanna. In order to identify the main meteorological factors influencing Epan, complete data from the D20 pan monitoring period, namely, 1979–2008, were selected for attribution calculations. The variations in the net radiation and saturated vapor pressure deficit are the main triggers that explain the ‘evaporation paradox’ phenomenon in Xishuangbanna.

Effects of plant diversity, soil microbial diversity, and network complexity on ecosystem multifunctionality in a tropical rainforest.

Plant diversity and soil microbial diversity are important driving factors in sustaining ecosystem multifunctionality (EMF) in terrestrial ecosystems. However, little is known about the relative importance of plant diversity, soil microbial diversity, and soil microbial network complexity to EMF in tropical rainforests. This study took the tropical rainforest in Xishuangbanna, Yunnan Province, China as the research object, and quantified various ecosystem functions such as soil organic carbon stock, soil nutrient cycling, biomass production, and water regulation in the tropical rainforest to explore the relationship and effect of plant diversity, soil microbial diversity, soil microbial network complexity and EMF. Our results exhibited that EMF decreased with increasing liana species richness, soil fungal diversity, and soil fungal network complexity, which followed a trend of initially increasing and then decreasing with soil bacterial diversity while increasing with soil bacterial network complexity. Soil microbial diversity and plant diversity primarily affected soil nutrient cycling. Additionally, liana species richness had a significant negative effect on soil organic carbon stocks. The random forest model suggested that liana species richness, soil bacterial network complexity, and soil fungal network complexity indicated more relative importance in sustaining EMF. The structural equation model revealed that soil bacterial network complexity and tree species richness displayed the significantly positive effects on EMF, while liana species richness significantly affected EMF via negative pathway. We also observed that soil microbial diversity indirectly affected EMF through soil microbial network complexity. Soil bulk density had a significant and negative effect on liana species richness, thus indirectly influencing EMF. Simultaneously, we further found that liana species richness was the main indicator of sustaining EMF in a tropical rainforest, while soil bacterial diversity was the primary driving factor. Our findings provide new insight into the relationship between biodiversity and EMF in a tropical rainforest ecosystem and the relative contribution of plant and soil microibal diversity to ecosystem function with increasing global climate change.

Hanseniaspora menglaensis f.a., sp. nov., a novel apiculate yeast species isolated from rotting wood.

Two apiculate strains (NYNU 181072 and NYNU 181083) of a bipolar budding yeast species were isolated from rotting wood samples collected in Xishuangbanna Tropical Rainforest in Yunnan Province, southwest PR China. On the basis of phenotypic characteristics and the results of phylogenetic analysis of the D1/D2 domain of the large subunit (LSU) rRNA, internal transcribed spacer (ITS) region and the actin (ACT1) gene, the two strains were found to represent a single novel species of the genus Hanseniaspora, for which the name Hanseniaspora menglaensis f.a., sp. nov. (holotype CICC 33364T; MycoBank MB 847437) is proposed. In the phylogenetic tree, H. menglaensis sp. nov. showed a close relationship with Hanseniaspora lindneri, Hanseniaspora mollemarum, Hanseniaspora smithiae and Hanseniaspora valbyensis. H. menglaensis sp. nov. differed from H. lindneri, the most closely related known species, by 1.2 % substitutions in the D1/D2 domain, 2.5 % substitutions in the ITS region and 5.4 % substitutions in the ACT1 gene, respectively. Physiologically, H. menglaensis sp. nov. can also be distinguished from H. lindneri by its ability to assimilate d-gluconate.

Mapping foliar photosynthetic capacity in sub-tropical and tropical forests with UAS-based imaging spectroscopy: Scaling from leaf to canopy

Accurate understanding of the variability in foliar physiological traits across landscapes is critical to improve parameterization and evaluation of terrestrial biosphere models (TBMs) that seek to represent the response of terrestrial ecosystems to a changing climate. Numerous studies suggest imaging spectroscopy can characterize foliar biochemical and morphological traits at the canopy scale, but there is only limited evidence for retrieving canopy photosynthetic capacity (e.g., maximum carboxylation rate, Vc,max and maximum electron transport rate, Jmax). Moreover, the effect of canopy structure within forest communities on scaling up spectra-trait relationships from leaf to canopy level is not well known. To advance the spectra-trait approach and enable the estimation of key traits using remote sensing, we collected imaging spectroscopy data from an Unoccupied Aerial System (UAS) platform over two forest sites in China (a subtropical forest in Mt. Dinghu and a tropical rainforest in Xishuangbanna). At these sites, we also collected ground measurements of leaf spectra and traits, including biochemical (leaf nitrogen, phosphorus, chlorophyll, and water content), morphological (leaf mass per area, LMA) and physiological (Vc,max25 and Jmax25) traits (n = 135 tree-crowns from 42 species across two sites). Using a partial least-squares regression (PLSR) approach, we built and tested spectra-trait models with repeated cross-validation. The spectral models developed with leaf spectra were directly transferred to canopy spectra to evaluate the effect of canopy structure. We further applied canopy spectral models to map these traits at individual tree-crown scale. The results demonstrate that (1) UAS-based canopy spectra can be used to estimate Vc,max (R2 = 0.55, nRMSE = 11.79%), Jmax (R2 = 0.54, nRMSE = 12.34%), and five additional foliar traits (R2 = 0.38–0.60, nRMSE = 10.11–13.56%) at the tree-crown scale with demonstrated generalizability across two sites; (2) canopy structure strongly affects the spectra-trait relationships from leaf to canopy level, but the effects vary considerably across foliar traits and cannot be well captured by the 4SAIL canopy radiative transfer model. UAS-based imaging spectroscopy maps large variability in all foliar traits (including physiological traits) with spatially explicit information, reproducing the field-observed inter- and intra-specific variations. These results demonstrate the capability of using UAS-based imaging spectroscopy for characterizing the variability of foliar physiological traits at individual tree-crown scale over forest landscapes and highlight the similar generalizability but different biophysical mechanisms underlying spectra-trait relationships at leaf and canopy levels.

Variation characteristics of microorganisms at different soil depths of typical forests in southwest China.

Microbial biomass and community structure play a significant role in soil carbon cycling. There is a large amount of organic carbon in the subsoil, but most studies on soil microbial community have focused on the surface soil. The changes and influencing mechanisms of microbial community in subsoil are unclear. We analyzed soil microbial biomass and community structure at different soil depths (0-20, 20-40, 40-60, 60-80, and 80-100 cm) in three typical forests in southwest China, Xishuangbanna tropical rain forest, Ailao Mountain subtropical broad-leaved forest, and Lijiang temperate coniferous forest, by using phospholipid fatty acid technology, to explore their variation characteristics and influencing factors in different forests and soil depths. The results showed that contents of soil organic carbon and total nitrogen decreased gradually, microbial biomass declined significantly. The ratio of Gram-positive bacteria to Gram-negative bacteria (G+:G-) reduced gradually, while the ratio of fungi to bacteria (F:B) increased with the increasing soil depth. Microbial community turned from G--dominated which adapted to eutrophic environment into G+-dominated which adapted to oligotrophic environment. The three forest types differed little in soil microbial biomass, but different significantly in microbial community structure. Ailao Mountain subtropical broad-leaved forest and Lijiang temperate coniferous forest had much higher F:B at 0-20 cm than Xishuangbanna tropical rain forest, while significantly higher G+:G- at 0-100 cm in Xishuangbanna tropical rain forest was observed. Results of the redundancy analysis showed that the contents of soil organic carbon and total nitrogen were the main factors determining microbial biomass, with combined explanation of 78.3%. Results of the stepwise regression analysis showed that C:N was the most important driving factor on F:B and G+:G-. The change in microbial community structure and the decrease in biomass along soil profile might strongly affect the dynamics of soil organic carbon in southwest China forests.

Barnettozyma menglunensis f.a., sp. nov., a novel yeast species isolated from rotting wood.

A novel yeast species is described based on three strains isolated from rotting wood samples from Xishuangbanna Tropical Rainforest in Yunnan Province, PR China. Strain NYNU 1811121 was isolated in Menglun, Mengla, while strains NYNU 18982 and NYNU 181096 were recovered in Mengyang, Jinghong. Analysis of the sequences of the D1/D2 domain of the large subunit rRNA gene and the internal transcribed spacer (ITS) region (ITS1-5.8S-ITS2) revealed that the novel strains were closely related to the type strain of [Candida] sanyiensis, but with 6.9 % nucleotide substitutions in the D1/D2 domain and 8.2 % substitutions in the ITS region. The three novel strains can also be distinguished from C. sanyiensis in terms of the ability to assimilate trehalose and d-gluconate and to grow at 35 °C, as well as the inability to ferment glucose. Based on molecular analyses and phenotypic characteristics, the name Barnettozyma menglunensis f.a., sp. nov. is proposed with the holotype CBS 16011T (MycoBank 845375).

Multi-omics and network pharmacology study reveals the effects of Dengzhan Shengmai capsule against neuroinflammatory injury and thrombosis induced by ischemic stroke

Ethnopharmacological relevanceDengzhan Shengmai capsule (DZSM) is a traditional herb medicine used by Dai, an ethnic-minority community living in Xishuang banna tropical rainforest in Southwest of China. It was originally intended to treat disorders caused by insufficient brain function, characterized by gibberish, unresponsiveness, or confusion. Accumulating clinical evidences exhibited that it is effective on treating ischemic stroke (IS). However, the action of DZSM against IS needs to be further elucidated. Aim of the studyTo investigate the effect of DZSM and its active components against IS and the way of its action by multi-omics and network pharmacology. Materials and methodsA middle cerebral artery occlusion/reperfusion (MCAO/R) rat model was established to investigate the effect of DZSM on the focal cerebral ischemia/reperfusion injury. An integrated strategy combining metabolomics, network pharmacology and transcriptomics was performed to systematically clarify the underlying mechanism of action of DZSM against IS. AutoDock Vina was applied to conduct molecular docking simulation for the binding between the potential active compounds and targets. Arachidonic acid (AA) induced platelet aggregation and lipopolysaccharide (LPS) stimulated microglial cells BV2 inflammation models were applied for the in vitro validation of effects of DZSM and its potential active compounds. ResultsIn MCAO/R rats, DZSM could significantly reduce the infarct volume. Putative target prediction and functional enrichment analysis based on network pharmacological indicated that the key targets and the potential active compounds played important roles in DZSM's treatment to IS. The targets included four common genes (PTGS1, PTGS2, NFKB1 and NR1I2) and five key TFs (NFKB1, RELA, HIF1A, ESR1 and HDAC1), whilst 22 potential active compounds were identified. Molecular docking indicated that good binding affinity have been seen between those compounds and NR1I2, NFKB1, and RELA. Multi-omics study revealed that DZSM could regulate glutamate by influencing citrate cycle and glutamate involved pathways, and have showed neuroprotection activity and anti-inflammation activity by inhibiting NF-κB pathway. Neuroprotective effects of DZSM was validated by regulating of NF-κB signaling pathway and its downstream NO, TNF-α and IL-6 cytokines contributed to the activity of DZSM and its active compounds of scutellarin, quercetin 3-O-glucuronide, ginsenoside Rb1, schizandrol A and 3, 5-diCQA, whilst the antithrombotic activity of DZSM and its active compounds of schisanhenol, apigenin and schisantherin B were screened out by anti-platelet aggregation experiment. ConclusionDZSM could against IS via regulating its downstream NO, TNF-α and IL-6 cytokines through NF-κB signaling pathway and alleviating thrombosis.

Activity-density and spatial distribution of termites on a fine-scale in a tropical rainforest in Xishuangbanna, southwest China

The community composition and activity-density of termites can influence nutrient cycling and other ecological functions. However, the spatial distribution and the activity-density of termites on a fine-scale in tropical forests are still unknown. We checked the spatial distribution patterns of the feeding groups and species of termites and their co-occurrence pattern in a 1-ha (100 m × 100 m) plot, and their correlation with the environmental factors. We used a standard protocol to collect termite assemblages and classified them into five feeding groups based on their preferred diet: fungus growers, litter feeders, soil feeders, soil-wood feeders, and wood feeders. We measured the environmental factors: soil pH, litter mass, aboveground plant biomass, and topographic position index (TPI). Soil-wood feeders showed the highest activity-density, followed by wood feeders, fungus growers, soil feeders, and litter feeders. Soil-wood feeders and fungus growers demonstated a strong correlation while litter feeders showed weak correlations with other feeding groups. Termite feeding groups and most of the termite species displayed a positive association with the high TPI and the low soil pH patches. Our results indicated that the examined environmental factors influenced the termite community assemblages and distribution patterns on a fine-scale in tropical rainforests.

基于树形结构的木棉叶功能性状差异性研究

PDF HTML阅读 XML下载 导出引用 引用提醒 基于树形结构的木棉叶功能性状差异性研究 DOI: 10.5846/stxb202006031431 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（31860206） Variation in leaf functional traits of Bombax ceiba Linnaeus communities based on tree structure Author: Affiliation: Fund Project: The National Natural Science Foundation of China (General Program, Key Program, Major Research Plan) 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:叶功能性状不仅反应植物对资源的利用能力，还涉及植物对自身结构和环境的生存适应策略。以不同生长阶段的木棉为研究对象，于2019年12月实地测量树高、冠幅等5个主要树形因子和采样测定叶面积、比叶面积、叶干物质含量、叶片含水量等14个叶功能性状，分析其在不同生长阶段的变化规律和相互关系，探讨叶功能性状对树形结构的响应。结果表明：不同生长阶段的木棉叶功能性状之间存在差异（P<0.05），且表现出一定的相关性（P<0.05，P<0.01）；木棉叶片的面积、长度、宽度、周长、鲜重、饱和重、干重、比叶质量和干物质含量等功能性状是随生长阶段变化的主要指标。影响木棉叶片各性状的树形因子也不相同，其中叶面积主要受到冠幅的影响，叶片鲜重和饱和重主要受到枝下高的影响，叶片干重和相对含水量主要受到树高的影响，比叶面积、叶片含水量和干物质含量主要受到树高、尖削度的影响，比叶质量主要受到胸径、尖削度、树高的影响。随着木棉的生长，叶功能性状表现出受树形结构的影响而具有较强的表型可塑性，有利于其适应内外环境的变化。因此，叶功能性状之间的变化差异和相关组合，反映了不同生长阶段的木棉对树形结构的适应性调整和对资源的利用策略，在一定程度上为探索西双版纳热带雨林区的生态保护和可持续发展提供相关科学依据。 Abstract:The leaf functional traits of plants not only reflect their abilities to use resources, but also represent their adaptation strategies to structural and environmental changes. Therefore, leaf functional traits are critical indicators of biogeochemical coupling in terrestrial ecosystems. In the present study, Bombax ceiba Linnaeus at different growth stages was taken as the main research subject, five main tree shape factors (i.e., height and crown breadth) were measured, and 14 leaf functional traits were quantified, including leaf area, specific leaf area, leaf dry matter content and leaf water content. We conducted the research in Menglun Town, Mengla County, Xishuangbanna Autonomous Prefecture in December 2019. We analyzed the changing patterns and mutual relations at different growth stages, and explored the responses of leaf functional traits to tree structure based on a variety of statistical analysis methods (i.e., One-way analysis of variance and multiple linear stepwise regression analysis). The results showed that leaf functional traits of Bombax ceiba Linnaeus differed in different growth periods (from primary growth stage to tertiary growth stage)(P<0.05), although they were also correlated certainly (P<0.05,P<0.01). Principal component analysis showed that leaf area, leaf length, leaf width, leaf perimeter, leaf fresh weight, leaf saturated weight, leaf dry weight, leaf mass per area, and leaf dry matter content were the main indicators with the increasing growth stage. The pattern of leaf functional traits was affected by various tree factors, which formed the best functional combination through the functional coordination among multiple characters so that plants could well adapt to environmental changes. We found that leaf area was mainly affected by the crown breadth. The leaf fresh weight and leaf saturated weight were mainly affected by the height to crown base. The leaf dry weight and leaf relative water content were mainly affected by the height, specific leaf area, leaf water content and leaf dry matter content were mainly affected by the height and taperingness, and leaf mass per area was mainly affected by the diameter, taperingness and height. With the growth of Bombax ceiba Linnaeus, the leaf functional traits showed strongly phenotypic plasticity influenced by tree structure, which was helpful to adapt to the changes in internal and external environment. Therefore, the variation and related combinations of leaf functional traits at different periods reflect the adaptability of Bombax ceiba Linnaeus to the tree structure and resource utilization strategies, which to a certain extent also provide relevant scientific basis for the exploration of the ecological protection and sustainable development of the tropical rain forest in Xishuangbanna. 参考文献 相似文献 引证文献

Observational study of the physical and chemical characteristics of the winter radiation fog in the tropical rainforest in Xishuangbanna, China

Observational study of the physical and chemical characteristics of the winter radiation fog in the tropical rainforest in Xishuangbanna, China

Microbial processes responsible for soil N2O production in a tropical rainforest, illustrated using an in situ15N labeling approach

Tropical forests are important contributors for N2O emissions from soil to the atmosphere; however, the microbial processes responsible for soil N2O production in tropical forest soils remain unclear. In this study, we employed a 40-day-long in situ15NO3− labeling experiment to determine the microbial processes that are responsible for N2O production in an undisturbed tropical rainforest in Xishuangbanna, southwest China. We observed that during the experiment, most of the 15N-labeled NO3− were immobilized and only 0.027% was emitted as N2O. Of the total N2O production, 3.1% was from the added 15N-labeled NO3−, 48.6% was from the added NH4+ and native N. Within the first 27 h, nitrification (heterotrophic and autotrophic nitrification) was the predominant microbial process of N2O production, accounting for 97.6% of total soil N2O emissions, whereas denitrification and co-denitrification resulted in only 1.6% and 0.9% emissions, respectively. To the best of our knowledge, this is the first study to demonstrate that nitrification, rather than denitrification, is the predominant microbial process of N2O production in situ in the study area in the tropical forest.

Combining camera‐trap surveys and hunter interviews to determine the status of mammals in protected rainforests and rubber plantations of Menglun, Xishuangbanna, SW China

AbstractHunting and deforestation are the two biggest threats to vertebrates in Southeast Asia. In the last 50 years, monoculture rubber plantations replaced large areas of tropical rainforests in Xishuangbanna, southwest China. We set up camera traps at 109 stations (57 in forest reserves and 52 in rubber plantations) to determine the distribution of mammal species in Menglun, Xishuangbanna. We also interviewed 37 experienced hunters (mean age: 54) in the study area to understand their perceptions of species abundance trends. We used hierarchical multispecies occupancy modelling to determine the effect of distance to village, distance to forest edge and elevation on mammal occupancy after accounting for imperfect detection. We used non‐parametric tests for the rank data to evaluate perceived species trends. Using a combination of historical literature (1954–1985), hunter interviews, direct observations and camera‐trap surveys, we only recorded 56% (15 out of 27) of the medium‐to‐large sized (&gt;1 kg) mammal species known previously from the study region. Interviews suggested that current population densities of all extant mammal species are below historical levels. Our camera traps captured 11 mammal species in the forest reserve and only two species in rubber plantations. Low capture rates (10 captures) in rubber mean we could only determine mammal occupancy in forests. Environmental variables did not affect community level mammal occupancy in forests, but common muntjac (Muntiacus muntjak) and the northern pig‐tailed macaque (Macaca leonina) avoided forest edges. At the time of the survey, hunting was still prevalent in the region. Therefore, conservation interventions that end both hunting and deforestation are urgently needed to stabilize and increase mammal populations in the region.

Kazachstania jinghongensis sp. nov. and Kazachstania menglunensis f.a., sp. nov., two yeast species isolated from rotting wood

Five yeast strains were isolated from rotting wood samples collected in the Xishuangbanna Tropical Rainforest, Yunnan Province, PR China. Phylogenetic analysis of the D1/D2 domains of the large subunit rRNA gene indicated that these strains represent two novel species of the genus Kazachstania. Kazachstania jinghongensis sp. nov. produces one to two spherical ascospores per ascus, and is most closely related to Kazachstania lodderae and Kazachstania spencerorum. Kazachstania jinghongensis sp. nov. differed from the type strains of the two latter species by 13-24 substitutions in the D1/D2 domains and by 39-56 substitutions in the ITS regions. Kazachstania menglunensis f.a., sp. nov. is a member of the Kazachstania jiainica subclade, but the formation of ascospores was not observed on various sporulation media. Kazachstania menglunensis sp. nov. differed from other members of the subclade by 23-26 substitutions in the D1/D2 domains and by more than 67 substitutions in the ITS regions. The holotype of Kazachstania jinghongensis sp. nov. is NYNU 17944 (CBS 15232) and the holotype of Kazachstania menglunensis sp. nov. is NYNU 18913 (CBS 16054).

Saturnispora galanensis sp. nov., a yeast species isolated from rotting wood.

Three strains of a novel yeast species were isolated from rotting wood in the Xishuangbanna Tropical Rainforest, Yunnan Province, PR China. Sequence analysis of the D1/D2 domains of the large subunit rRNA gene and the internal transcribed spacer (ITS) regions showed that the novel species represents a member of the genus Saturnispora. It differed from its closest known species, Saturnispora sekii CBS 10931T, by 1.3 % nucleotide substitutions in the D1/D2 domains and by 2.2 % nucleotide substitutions in the ITS regions, respectively. In contrast to Saturnispora sekii, the novel yeast species was unable to assimilate glycerol, dl-lactate, succinate and citrate, and grow at 37 °C. The name Saturnispora galanensis sp. nov. is proposed to accommodate these strains, with NYNU 1797 as the holotype.

Candida yunnanensis sp. nov. and Candida parablackwelliae sp. nov., two yeast species in the Candida albicans/Lodderomyces clade

During studies on the yeast communities associated with rotting wood in the Xishuangbanna Tropical Rainforest in PR China, four novel yeast strains were found. Phylogenetic analysis based on the concatenated sequences of the D1/D2 domains of the large subunit rRNA gene and the ITS regions showed that these strains represented two novel species in the Candida albicans/Lodderomyces clade. The novel species, represented by strains NYNU 17948 and NYNU 17981, formed a clade with Candida maltosa and Candida baotianmanensis, with 1-1.8% sequence divergence in the D1/D2 domains and 8.9-10% sequence divergence in the ITS regions. The other novel species, represented by NYNU 17105 and NYNU 17763, is most closely related to Candida blackwelliae with 0.7 % sequence divergence in the D1/D2 domains and 6.9 % sequence divergence in the ITS regions. The two novel species could be distinguished from their closest described species in terms of physiological traits. The two novel species are described as Candida yunnanensis sp. nov. (holotype NYNU 17948) and Candida parablackwelliae sp. nov. (holotype NYNU 17763).

Soil respiration after six years of continuous drought stress in the tropical rainforest in Southwest China

Climate models predict that droughts will increase in Southeast Asia, yet little is known about how soil respiration (Rs) and its components heterotrophic respiration (Rh) and autotrophic respiration (Ra) will change following drought years. To clarify this issue and to detect underlying mechanisms, we conducted a 2-year field experiment in the seventh and eighth year of long-term artificially droughted plots within a tropical rainforest in Xishuangbanna, southwest China. We separated Rh and Ra by trenching and we measured dissolved organic carbon in the soil and microbial biomass. In average, the drought stress, reduced through-fall by 50%, reduced fine root biomass by 36%. Although Ra declined by 35%, active inorganic N and Rh increased by 31% and 29%. Further, the coefficient of determination (R2) between soil microbial community composition, mainly, group-specific phospholipid fatty acid and the variation of Rh was among 17%–59% during the dry and rainy season of 2018. However, changes in dissolved organic carbon, microbial biomass carbon and nitrogen, ammonium nitrogen, were inconsistent with the increase in Rh. There was an inconsistent significant positive correlation between seasonal change of CO2 flux and these processes dynamic across 2017 and 2018. Soil temperature, soil moisture, and litterfall jointly determined annual variation in Rs and Rh across two years. These findings have improved understanding of how long-term drought stress influences soil CO2 effluxes via change of soil-based biochemical indicators (like fine root, active inorganic nitrogen, and soil microorganisms).

Wickerhamomyces menglaensis f.a., sp. nov., a yeast species isolated from rotten wood.

Five strains, NUNU 16637, NYNU 16645, NYNU 1673, NYNU 1680 and NYNU 1689, of a novel ascomycetous yeast were isolated from the Xishuangbanna tropical rainforest, Yunnan Province, PR China. The five strains shared identical sequences in both of the D1/D2 domains of the large subunit rRNA gene and the internal transcribed spacer (ITS) regions. Sequence analysis showed that they represent undescribed yeast species belonging to the genus Wickerhamomyces. They differed from their closest known species, Wickerhamomyces xylosivorus NBRC 111553T, by 3.4 % sequence divergence (14 substitutions and six gaps out of 584 bp) in the D1/D2 domains and by 9.6 % sequence divergence (28 substitutions and 24 gaps over 543 bp) in the ITS regions, respectively. The five strains of novel species reproduced asexually; no sexual reproduction could be found. In contrast to W. xylosivorus, the novel yeast species were able to assimilate l-arabinose, inulin, soluble starch, d-mannitol and citrate, and unable to assimilate trehalose, raffinose, 5-keto-d-gluconate, d-gluconate, ethanol, ethylamine and cadaverine. Growth was observed at 35 °C. The name Wickerhamomyces menglaensis f.a., sp. nov. is proposed to accommodate these strains, with NYNU 1673 as the holotype.