THE FLORISTIC CHARACTERISTICS OF THE TROPICAL RAINFOREST IN XISHUANGBANNA

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THE TROPICAL RAINFOREST VEGETATION IN XISHUANGBANNA

The tropical rainforest in Xishuangbanna, Yunnan Province of China, is introduced in detail in this paper. Situated at the northern margin of tropical mainland SE Asia and controlled by monsoon climate, the region has been climatically at the lower limits for tropical rainforests, however true tropical rainforests exist and develop luxuriantly in the region. The reasons for this are discussed. In general phytocoenological characteristics such as vertical stratification, life form spectrum, species riches etc. the tropical rainforest in Xishuangbanna is very similar to the typical tropical rainforest in equatorial region, but it is characterized by a clear change of physiognomy between different season. As occurred at the latitudinal and altitudinal limits of tropical rainforest, the flora of the rainforest is endowed with the nature of northern margin of tropical zone of SE Asia and is transitional toward the flora of subtropical forest of China. In recent years the region has been opened up to use in

Study on the Current Situation and Protection Countermeasures of Wild Plant Resources in Xishuangbanna National Nature Reserve

[Objective] The aim was to study the current situation and protection countermeasures of wild plant resources in Xishuangbanna National Nature Reserve. [Method] The current situation of wild plant resources in Xishuangbanna National Nature Reserve was researched by means of route survey, sample plot survey and literature survey, and then the main impact factors of wild plant resources were analyzed by using participatory rural appraisal and problem tree analysis, finally protection countermeasures were put forward according to current situation and main impact factors. [Result] There were 2 779 species of vascular plants belonging to 214 families and 1 012 genera (including subfamilies and varieties) in Xishuangbanna National Nature Reserve, among them, there existed 261 species of pteridophyte belonging to 41 families and 91 genera, 14 species of gymnosperm belonging to 6 families and 6 genera, and 2 504 species of angiosperm belonging to 167 families and 915 genera. Wild plant resources in reserve were mainly affected by planting under forest, habitat fragmentation, cutting trees, collection and utilization of no-timber products, development of animal husbandry, insufficient recognition of community residents to reserve management establishment and lots of floating population. In the future, wild plant resources in reserve could be protected through strengthening propaganda, education and management, enforcing the law strictly and other countermeasures. [Conclusion] The study could provide theoretical foundation for the protection of wild plant resources in Xishuangbanna National Nature Reserve.

FOREST LANDSCAPE AND BIRD DIVERSITY IN MOUNTAIN REGION, XISHUANGBANNA, YUNNAN

１ＧＥＮＥＲＡＬＳＩＴＵＡＴＩＯＮＯＦＴＨＥＳＴＵＤＩＥＤＡＲＥＡ１．１ＮａｔｕｒａｌＥｎｖｉｒｏｎｍｅｎｔＴｈｅｓｔｕｄｙｗａｓｃｏｎｄｕｃｔｅｄｉｎｔｈｅＪｉｎｕｏＭｏｕｎｔａｉｎ（２０°５３′１１″－２２°９′５９″Ｎ，１００°５５′３３″－１...

Co-opetition Development of Cultural Tourism Complexes in Xishuangbanna: A Case Study of Gaozhuangxishuangjing and Xishuangbanna-Based Wanda International Resort

The cultural tourism complex is a comprehensive development model with cultural soft power as its core competitiveness, and is an industrial development system with tourism as the forerunner, culture as the core, and real estate as the platform and consumption carrier. The development status and trend of the cultural tourism complex as a new format of tourism industry integration under the guidance of the national strategy of all-for-one tourism are worthy of attention and discussion. With Xishuangbanna's two cultural tourism complexes of Gaozhuangxishuangjing and Xishuangbanna-based Wanda International Resort as the research object, this paper compared the similarities and differences of the two tourism complexes in their development and their respective problems, and analyzed the basis and condition for their co-opetition development. The ultimate goal of this paper was to seek the relevant countermeasures and suggestions for the two cultural tourism complexes to complement each other, promote each other, and jointly promote the development of tourism in Xishuangbanna.

How to Develop Rubber Production in Xishuangbanna Dai Autonomous Prefecture?

The natural rubber planting area in Xishuangbanna Dai Autonomous Prefecture accounts for about 30% of rubber planting area in China. At the end of 2013,the rubber planting area in Xishuangbanna Dai Autonomous Prefecture was 29. 4 ha,the tapped rubber plantation area was 17. 49 ha,and the dry rubber production was 317000 t. Currently,the production and management level of rubber plantation has declined in Xishuangbanna Dai Autonomous Prefecture,the tapping technique is outdated,and the tapping technology management system is difficult to implement. Therefore,some ways can be employed to promote the development of rubber industry such as enhancing the operation and management level of rubber industry,organizing the rubber production team,and developing the new rubber farmers' cooperatives.

Diversity of Cultivable Actinomycetes in Tropical Rainy Forest of Xishuangbanna, China

In order to obtain much more un-known actinomycetes for discovering new drug lead, one hundred soil samples were collected from five national natural protection areas of tropical rain forests, Mengla, Menglun, Mandian, Xiaomengyang and Guanping, in Xishuangbanna, Yunnan, China. 1652 purified cultures of actinobacteria were isolated from these samples by using 5 media. The 16S rRNA gene sequences of 388 selected strains were analyzed, and the phylogenetic analysis was carried out. 35 genera which belong to 8 orders and 14 families of the Class actinobacteria were identified. It is showed from research results that actinomycete diversity in tropical rain forest of Xishuangbanna is the highest comparing with all areas studied in our laboratories before. Selective isolation methods for un-known actinomycetes from soil samples, including medium and inhibitors are discussed in this paper.

Perception and Attitudes of Local Communities Towards Wild Elephant-related Problems and Conservation in Xishuangbanna,Southwestern China

The problem of wild elephants, or human-elephant conflict (HEC), influences the daily life of local communities and hinders the conservation of wild elephants.The perception and attitudes of local communities who inhabited the frontiers between human activities and wild elephant movement are important to the mitigation of the HEC and conservation of wild elephants. To analyze the perception and attitudes of local communities, the Participatory Rural Appraisal (PRA) was used in the investigation of 423 interviewees from 22 villages in Xishuangbanna from July 2009 to February 2010. The results indicated that local communities had their views on the elephant-related problems. In field survey, we found that 66.5% of interviewees were willing to support, participate in, and assist in the conservation of wild elephants;33.5% of interviewees were opposed or indifferent to such conservation, because their livelihoods and even their lives were endangered by wild elephants. These views and attitudes were influenced by local communities′perception of HEC, education level, gender and self-interest. Therefore, it is necessary to analyze the diverse views among local communities and balance profits and costs in addressing HEC.

Forest vegetation of Xishuangbanna,south China

Xishuangbanna of southern Yunnan is biogeographically located at a transitional zone from tropical southeast (SE) Asia to subtropical east Asia and is at the junction of the Indian and Burmese plates of Gondwana and the Eurasian plate of Laurasia. The region, though surprisingly far from the equator and at a relatively high altitude, has a rich tropical flora and a typical tropical rain forest in the lowland areas. Based on physiognomic and ecological characteristics, floristic composition and habitats combined, the primary vegetation in Xishuangbanna can be organized into four main vegetation types: tropical rain forest, tropical seasonal moist forest, tropical montane evergreen broad-leaved forest and tropical monsoon forest. The tropical rain forest can be classified into two subtypes, i.e. a tropical seasonal rain forest in the lowlands and a tropical montane rain forest at higher elevations. The tropical sea-sonal rain forest has almost the same forest profile and physiognomic characteristics as equatorial lowland rain forests and is a type of truly tropical rain forest. Because of conspicuous similarity on ecological and floristic characteristics, the tropical rain forest in Xishuangbanna is a type of tropical Asian rain forest. However, since the tropical rain forest of Xishuangbanna occurs at the northern edge of tropical SE Asia, it differs from typical lowland rain forests in equatorial areas in having some deciduous trees in the canopy layer, fewer megaphanerophytes and epiphytes but more abundant lianas and more plants with microphyll. It is a type of semi-evergreen rain forest at the northern edge of the tropical zone. The tropical montane rain forest occurs at wet montane habitats and is similar to the lower montane rain forest in equatorial Asia in floristic composition and physiognomy. It is a type of lower montane rain forests within the broader category of tropical rain forests. The tropical seasonal moist forest occurs on middle and upper limestone slopes. It is similar to the tropical montane evergreen broad-leaved forest in the region in physiognomy, but differs from the latter in floristic composition. It is a vegetation type on limestone at high elevations. The monsoon forest in Xishuangbanna is a tropical deciduous forest under the influence of a strong monsoon climate and is considered to be a transitional vegetation type between a tropical rain forest and savanna in physiognomy and distribution. The tropical montane evergreen broad-leaved forest is the main montane vegetation type in the region. It is dominated largely by the families Fagaceae, Euphorbiaceae, Theaceae and Lau-raceae. It differs from tropical lower montane rain forests in its lack of epiphytes and in having more abundant lianas and plants with compound leaves. It is considered to be a distinct vegetation type from the northern margin of mainland southeastern Asia, controlled by a strong seasonal climate, based on its floristic and physiognomic characteristics.

Variation in photosynthetic photon flux density within a tropical seasonal rain forest of Xishuangbanna, south-western China

The effects of canopy development, solar angle, and weather conditions on temporal variation in photosynthetic photon flux density(PPFD) at three heights within a tropical rain forest canopy in Xishuangbanna, China, were examined. PPFD was measured every second and stored as 10-min averages from 1 December 2002 to 30 November 2003. PPFD variability was examined at three different temporal scales. Specific days in March, September, and December with clear and overcast sky conditions were selected to separate the effects of leaf area index(LAI) and solar angle on diurnal variability. On both clear and overcast days, mean daily average PPFD was significantly different between March and September at all heights, except 10 m on clear days, suggesting that LAI directly influences PPFD. In contrast, the differences in daily average PPFD among three heights between September and December were likely due to variation in solar angle. In addition, daily average PPFD at all locations were significantly lower under overcast than clear sky conditions in March, September and December. Over the year-long study, the mean daily total PPFD at 21 m, 10 m and 4 m was 2.8, 2.7 and 0.7 mol/(m^2·d), which accounted for 9.7%, 9.4% and 2.4% of the daily PPFD above the canopy, respectively. Significant differences in mean daily total PPFD occurred at the same heights among different seasons, and diurnal, day-to-day and seasonal PPFD varied at different heights within the canopy. The possible effects of light variability on physiological and morphological responses of plants are discussed.

Effects of frugivorous birds on seed retention time and germination in Xishuangbanna, southwest China

The dispersal of many plants depends on transportation by birds as seed dispersers. The birds play an important role in long distance seed dispersal and may also affect seed germination. However, for plants who have many bird dispersers, the influence of dominant and non-dominant dispersers on retention time(dispersal distance) and germination remains poorly understood. In this study,we performed experiments with captive frugivorous birds and fruiting plant species to study the effects of dominant and non-dominant dispersers on seed retention time(SRT) and germination(seed germination percentage and germination speed). Our study showed a great interspecific variation in the effects of frugivorous birds on both SRT and germination. Some birds enhance the germination of a given plant species, but others do not. Generally, the dominant visitors improved the seed germination and performed longer seed retention time.

Origins of black carbon from anthropogenic emissions and open biomass burning transported to Xishuangbanna, Southwest China

Black carbon(BC) has importance regarding aerosol composition, radiative balance, and human exposure. This study adopted a backward-trajectory approach to quantify the origins of BC from anthropogenic emissions(BCAn) and open biomass burning(BCBB) transported to Xishuangbanna in 2017. Haze months, between haze and clean months, and clean months in Xishuangbanna were defined according to daily PM_(2.5)concentrations of >75, 35–75, and<35 μg/m^(3), respectively. Results showed that the transport efficiency density(TED) of BC transported to Xishuangbanna was controlled by the prevailing winds in different seasons.The yearly contributions to the effective emission intensity of BCAnand BCBBtransported to Xishuangbanna were 52% and 48%, respectively. However, when haze occurred in Xishuangbanna, the average BCAnand BCBBcontributions were 23% and 77%, respectively. This suggests that open biomass burning(BB) becomes the dominant source in haze months. Myanmar, India, and Laos were the dominant source regions of BC transported to Xishuangbanna during haze months, accounting for 59%, 18%, and 13% of the total, respectively. Furthermore, India was identified as the most important source regions of BCAntransported to Xishuangbanna in haze months, accounting for 14%. The two countries making the greatest contributions to BCBBtransported to Xishuangbanna were Myanmar and Laos in haze months, accounting for 55% and 13%, respectively. BC emissions from Xishuangbanna had minimal effects on the results of the present study. It is suggested that open BB in Myanmar and Laos, and anthropogenic emissions in India were responsible for poor air quality in Xishuangbanna.

Annual variation of carbon flux and impact factors in the tropical seasonal rain forest of Xishuangbanna, SW China

Two years of eddy covariance measurements of above- and below-canopy carbon fluxes and static opaque chamber and gas chromatography technique measurements of soil respiration for three treatments (bare soil, soil+litterfall, soil+litterfall+seedling) were carried out in a tropical seasonal rain forest. In addition, data of photosynthesis of dominant tree species and seedlings, leaf area index, litter production and decomposing speed, soil moisture, soil temperature and photosynthetic photon flux density within the forest were all measured concurrently. Data from January 2003 to December 2004 are used to present annual variability of carbon flux and relationships between carbon flux and impact factors. The results show that carbon flux of this forest presented unusual tendency of annual variation; above-canopy carbon fluxes were negative in the dry season (November-April) and mainly positive in the rainy season, but overall the forest is a carbon sink. Carbon flux has obviously diurnal variation in this tropical seasonal rain forest. Above-canopy carbon fluxes were negative in the daytime and absolute values were larger in the dry season than that in the rainy season, causing the forest to act as a carbon sink; at night, carbon fluxes were mainly positive, causing the forest to act as a carbon source. Dominant tree species have greater photosynthesis capability than that of seedlings, which have a great effect on above-canopy carbon flux. There was a significant correlation between above-canopy carbon flux and rate of photosynthesis of tree species. There was also a significant correlation between above-canopy carbon flux and rate of photosynthesis of seedlings; however, the below-canopy carbon flux was only significantly correlated with rate of photosynthesis of seedlings during the hot-dry season. Soil respiration of the three treatments displayed a markedly seasonal dynamic; in addition, above-canopy carbon fluxes correlated well with soil respiration, litterfall production, litterfall decomposition rate, precipitation, and soil moisture and temperature. A primary statistical result of this study showed that above-canopy carbon flux in this forest presented carbon source or sink effects in different seasons, and it is a carbon sink at the scale of a year.

Soil respiration in tropical seasonal rain forest in Xishuangbanna, SW China

With the static opaque chamber and gas chromatography technique, from January 2003 to January 2004 soil respiration was investigated in a tropical seasonal rain forest in Xishuangbanna, SW China. In this study three treatments were applied, each with three replicates: A (bare soil), B (soil+litter), and C (soil+litter+seedling). The results showed that soil respiration varied seasonally, low from December 2003 to February 2004, and high from June to July 2004. The annual average values of CO2 efflux from soil respiration differed among the treatments at 1% level, with the rank of C (14642 mgCO2· m-2. h-1)＞B (12807 mgCO2· m-2. h-1)＞A (9532 mgCO2· m-2. h-1). Diurnal variation in soil respiration was not apparent due to little diurnal temperate change in Xishuangbanna. There was a parabola relationship between soil respiration and soil moisture at 1% level. Soil respiration rates were higher when soil moisture ranged from 35% to 45%. There was an exponential relationship between soil respiration and soil temperature (at a depth of 5cm in mineral soil) at 1% level. The calculated Q1o values in this study,ranging from 2.03 to 2.36, were very near to those of tropical soil reported. The CO2 efflux in 2003was 5.34 kgCO2· m-2. a-1 from soil plus litter plus seedling, of them 3.48 kgCO2· m-2. a-1 from soil (accounting for 62.5%), 1.19 kgCO2· m-2. a-1 from litter (22.3%) and 0.67 kgCO2·m-2. a-1 from seedling (12.5%).

基于GRA和MCR的西双版纳州生态安全格局构建研究

构建基于现状的生态安全格局对维护生态安全、提高生境质量、推动可持续发展意义重大.以西双版纳傣族自治州为例,从水源涵养、土壤保持、生物多样性保护和生态敏感性4个方面选取14个指标因子,采用灰色关联分析(GRA)模型和最小累积阻力(MCR)模型划分生态安全等级,识别生态源地、廊道和节点,构建研究区生态安全格局,并提出差异化生态管控措施.结果表明:(1)研究区平均生态安全指数为0.571,处于一般安全水平.其中,安全等级面积占比为7.43%,较安全为39.23%,一般安全为13.23%,预警为23.64%,危险为16.47%;空间分布上,三县(市)生态安全水平均处于一般安全,且景洪市(0.573)>勐腊县(0.571)>勐海县(0.568),预警等级在景洪市和勐腊县的占比均超过27%.(2)研究区共识别出生态源地7934.91 km^(2);生态廊道132条,长度2188.82 km;生态节点53个.(3)研究区划分出3类生态保护分区.其中,生态保护区需保持水土、保护生物多样性;生态控制区需控制建设用地规模,提供生态产品;生产活动区需开展环境综合整治,改善人居环境.研究成果可为区域内开展生态安全保护提供依据,研究探索的基于GRA和MCR的生态安全格局研究方法可为类似研究提供参考.

西双版纳热带森林土壤有机碳积累-分配动态对蚂蚁筑巢活动的响应

蚂蚁筑巢能够通过影响土壤微生物及理化环境而直接或间接调控土壤有机碳各组分积累及分配动态。以西双版纳崖豆藤热带森林群落为研究样地,测定蚁巢和非巢地土壤碳库组分(总有机碳、易氧化有机碳、微生物生物量碳)含量及分配(易氧化有机碳/总有机碳、微生物生物量碳/总有机碳)的时空动态,分析蚂蚁筑巢引起热带森林土壤性质改变对有机碳组分积累与分配的影响特征。结果表明,1)蚂蚁筑巢显著促进土壤总有机碳及各组分含量的积累(P<0.01)。相较于非巢地,蚁巢土壤总有机碳、微生物生物量碳、易氧化有机碳含量分别提高了19.7%、35.4%和153.3%。2)蚂蚁筑巢显著影响土壤碳库各组分含量的时空变化(P<0.050)。其中,相较于非蚁巢,蚁巢土壤总有机碳、易氧化有机碳、微生物生物量碳含量季节变化的增幅分别为11.4%-30.1%、13.6%-72.3%、53.4%-212.2%;蚁巢土壤总有机碳、微生物生物量碳、易氧化有机碳含量沿土层降幅(43.1%-422.4%)显著高于非蚁巢(38.1%-111.4%)。3)蚁巢土壤微生物生物量碳(15.2%)和易氧化有机碳(36.9%)在总有机碳中分配均值均显著高于非巢地(7.5%-31.6%),蚁巢土壤微生物生物量碳分配沿土层降幅(63.1%)小于非蚁巢(75.2%),易氧化有机碳分配(277.2%)则大于非蚁巢(53.4%)。4)主成分分析表明,温湿度、pH、氨氮是调控蚁巢土壤有机碳组分积累的主要协同因子,温度和容重是蚁巢土壤有机碳组分分配的主控因子。蚂蚁筑巢主要通过改变土壤物理环境(微气候、酸碱性、通气性)和土壤氮库(铵氮)的状况,进而对土壤有机碳组分积累及组分分配产生重要影响。

STUDY ON THE PHYSICAL PROCESS OF WINTER VALLEY FOG IN XISHUANGBANNA REGION

Xishuangbanna of Yunnan Province is a famous tropical foggy region. A field experiment wascarried out from November 23 to 30 of 1997 during which fogs occurred regularly every day. In thepaper the characteristics of macrostructure of fog are analyzed and the physical processes offormation and dissipation of fog are studied. The results show that the Xishuangbanna valley fogforms firstly in the lower atmosphere with two-layer structures and then develops suddenly in thevertical direction after reaching the ground. Furthermore, the vegetation effect on the formationand dissipation of fog is discussed specially.

A novel mosquito-borne reassortant orbivirus isolated from Xishuangbanna,China

Dear Editor,The genus Orbivirus,within the family Reoviridae,includes 22 virus species(King et al.,2011).They are distributed globally,but are particularly prevalent in Europe,Asia,and Africa.In addition,they can be transmitted by ticks or other hematophagous insect vectors,including Culicoides,mosquitoes,and sandflies(Belaga-