西双版纳茅草山广西青梅群落学研究*

应用植物群落学的研究方法, 对西双版纳茅草山广西青梅群落进行了初步研究。该群落是以龙脑香科
的广西青梅和金缕梅科的细青皮为乔木上层优势树种, 群落分A 至E 层, 外貌以单叶、纸质、全缘、尾尖、
中叶为主的常绿大、中高位芽植物组成为特征, 层间木质藤本和附生植物丰富, 属热带季节雨林。该群落是
老挝热带季节雨林向北的伸延, 物种丰富, 动态结构稳定, 但分布面积狭小, 生态脆弱, 需重点保护     

引种保护植物对西双版纳极端冷年的春季物候响应

气温被普遍认为是春季物候期最主要的控制因子之一,然而低温对植物物候的影响效应一直都存在不同的观点。西双版纳由于地处热带地区的北缘,其气温相对于赤道附近的热带地区较低。自1959年以来,西双版纳热带植物园引入了来自世界各个热带地区的4万余种植物进行保护,之前的研究证明西双版纳的低温对这些引种植物的生长有很大影响。因此,1974年西双版纳出现的极端低温势必对引种植物造成极大威胁,同时也是对这些植物低温适应能力的一个考验。通过对比43种引种植物物候期（生长抽梢期与开花期）在1974年与常年的差异情况,分析不同来源（热带亚洲、热带美洲与热带非洲）引种植物对西双版纳低温的适应性。结果表明,经历西双版纳1974年初的极端低温之后,使81%的引种植物生长抽梢期提前,同时也造成35%的引种植物在该年没有开花;而植物生长抽梢提前的主要原因则是极端低温以及低温过后气温迅速回升。引种植物均能顺利度过1974年的最冷时期,并出现生长抽梢物候,这意味着引种植物在经历极端低温之后都能够进行正常的生长活动,但极端低温对引种植物繁殖活动的不利影响大于其对生长活动的影响;引种植物对西双版纳极端低温的适应能力由大到小顺序依次为：亚洲来源植物〉美洲来源植物〉非洲来源植物。因此在迁地保护植物的选择过程中,应多选择亚洲热带植物,其次为美洲热带植物,而对非洲热带植物的引入则需谨慎考察。     

西双版纳茅草山广西青梅群落学研究

应用植物群落学的研究方法,对西双版纳茅草山广西青梅群落进行了初步研究。该群落是以龙脑香科的广西青梅和金缕梅科的细青皮为乔木上层优势树种,群落分A至E层,外貌以单叶、纸质、全缘、尾尖、中叶为主的常绿大、中高位芽植物组成为特征,层间木质藤本和附生植物丰富,属热带季节雨林。该群落是老挝热带季节雨林向北的伸延,物种丰富,动态结构稳定,但分布面积狭小,生态脆弱,需重点保护。     

The pollination ecology of Paraboea rufescens (Gesneriaceae): a buzz-pollinated tropical herb with mirror-image flowers

BACKGROUND AND AIMS: Gesneriaceae is a pantropical plant family with over 3000 species. A great variety of pollination mechanisms have been reported for the neotropical members of the family, but the details of buzz-pollination and enantiostyly for the family have not been described. We investigated the floral biology and pollination ecology of Paraboea rufescens in Xishuangbanna, south-west China, considering three aspects: (1) the type of enantiostyly exhibited; (2) whether the species is self-compatible; and (3) whether pollinator behaviour could enhance the precision of pollen transfer between flowers of contrasting stylar orientation. METHODS: Flowering phenology was monitored once a month during vegetative growth, and once a week during flowering both in the field and under cultivation. Pollination manipulations and pollinator observation in the field were conducted. KEY RESULTS: Anthesis occurred early during the morning, and flowers remained open for 1-5 d, depending on weather conditions. Controlled pollinations revealed that P. rufescens is self-compatible, and exhibited inbreeding depression in seed set. Plants were pollinator limited in natural populations. The similar stylar deflection among flowers within a plant limits autonomous self-pollination as well as pollination between flowers. Two species of bumble bees (Bombus spp.), Amegila malaccensis and Nomia sp. effectively pollinated P. rufescens. These pollinators visited flowers in search of pollen with almost the same frequency. None of the pollinators appeared to discriminate between left- or right-handed flowers. CONCLUSIONS: Paraboea rufescens exhibits monomorphic enantiostylous flowers and a buzz-pollination syndrome. Floral morphology in P. rufescens and pollinator foraging behaviour seems likely to reduce self-pollination and pollinations between flowers of the same stylar deflection.     

热带季节雨林林冠上方和林内近地层CO2浓度的时空动态及其成因分析

 为探讨西双版纳独特地方气候背景下,热带季节雨林CO₂浓度的时空变化特征和不同时间尺度上环境因素对森林CO₂浓度时间分布的作用,以及 为研究热带季节雨林的碳通量、净生态系统交换量(Net ecosystem exchange, NEE)等提供支持,我们利用热带季节雨林林冠上方和林内近地层 CO₂浓度连续监测资料,结合同步气象资料进行了统计分析。研究结果表明：在植被生理活动、土壤呼吸以及林内湍流的共同作用下,西双版纳 热带季节雨林CO₂浓度表现出明显的日变化、季节变化和林冠上下差异。在日尺度上,林冠上方的CO₂浓度时间变化曲线为“单峰型”,林内近 地层CO₂浓度时间变化曲线为“双峰型”,造成林内近地层傍晚第二个峰值的主要因子是地形因子作用下形成的局地环流。在季节尺度上,林冠 上方CO₂浓度主要受林冠代谢作用的影响,呈现雨季低、干季高的特点,而林内近地层的CO₂浓度则主要受地表呼吸过程所控制,季节变化趋势 与林冠上方相反。林冠上方CO₂浓度低于林内近地层CO₂浓度,且差异较大;在日尺度上,各月（除12月外）CO₂浓度的最大差值皆大于80 mg·m ^－3,且出现在傍晚;在季节尺度上,最大值为-62.9 mg·m^－3,出现在10月,最小值为-8.4 mg·m^－3,出现在12月。     

Vegetation and fire history of a Chinese site in southern tropical Xishuangbanna derived from phytolith and charcoal records from Holocene sediments

Aim The aims of this paper are to reconstruct the vegetation and fire history over the past 2000 years in a well‐preserved rain‐forest area, to understand interactions between climate, fire, and vegetation, and to predict how rain forest responds to global warming and increased intensity of human activity. Location Xishuangbanna, south‐west China, 21–22° N, 101–102° E. Methods Phytolith (plant opal silica bodies) morphotypes, assemblages, and indices were used to reconstruct palaeovegetation and palaeoclimate changes in detail. Micro‐charcoal particles found in phytolith slides, together with burnt phytoliths and highly weathered bulliform cells, were employed to reconstruct a record of past fire occurrence. A survey of field sediments, lithology, and ¹⁴C dating were also employed. Results Phytoliths were divided into 11 groups and classified into 33 well‐described morphotypes according to their shape under light microscopy and their presumed anatomical origins and ecological significance. The phytolith assemblages were divided into six significant zones that reveal a complete history of vegetation changes corresponding to climate variation and fire occurrence. Phytolith assemblages and indices show that the palaeoclimate in the study area is characterized by the alternation of warm–wet and cool–dry conditions. Phytolith and charcoal records reveal that 12 fire episodes occurred. Comparison of burnt phytoliths with an aridity index (Iph) shows that fire episodes have a strong relationship with drought events. Main conclusions Our results indicate that fire occurrence in the tropical rain forest of Xishuangbanna is predominantly under the control of natural climate variability (drought events). Nearly every fire episode is coupled with a climatic event and has triggered vegetation composition changes marked by a pronounced expansion of grasses. This indicates that drought interacts with fire to exert a strong influence on the ecological dynamics of the rain forest. However, the impact of human activity in recent centuries is also significant. Our results are important for understanding the interactions between climate, fire, and vegetation, and for predicting how rain forest responds to global warming and increased human activity.     

西双版纳澜沧江河谷竹林蚊类群落学特征的初步研究

为了解热带竹林的蚊类群落学特征和继续探讨蚊类群落学的调查和分析方法,采用随意全捕积水较久树桩内蚊幼,并对调查资料进行群落学特征分析的方法开展研究,共发现库蚊亚科和巨蚊亚科的8属,14亚属,23种蚊虫;分析显示各蚊各上的优势度均较低;优势种侧白伊蚊、圆斑伊蚊和幼小库蚊的优热度仅分别是26.22、25.26和23.74;群薄的Shannon-Wiener多样性指数和均匀性指数分别为2.45和0.78。结论为此群薄蚊种丰富,但无任何蚊种占绝对优势,群落稳定性差。     

西双版纳植物区系的特点与亲缘

西双版纳植物区系经初步资料整理统计有种子植物 3336种 ,隶属于 1 1 4 0个属 ,大约 1 97个科。植物区系成分构成是热带分布的科和属分别占总科和属数的 60 .1 %和 83.5% ,在热带分布属中 ,又以热带亚洲成分占优势 (占 32 .8% )。通过植物区系组成和地理成分分析 ,认为该植物区系是热带性质的 ,属于热带亚洲区系的一部分 ,并带有明显热带边缘性质和几种地理成分交汇的特点。西双版纳植物区系与广西热带植物区系和海南热带植物区系在发生上同源 ,主要来自于古南大陆与古北大陆区系成分的融合 ,在发展上受热带亚洲植物区系的渗透和强烈影响。     

热带次生林火烧前后土壤节肢动物群落组成和分布特征的变化

西双版纳山区 ,刀耕火种轮歇农业是一种以火和休闲为特征的传统农业耕作方式 ,短期种植 ( 1～3年 ) ,长期休闲 ( 6～ 8年到 2 0年以上 )的点播种植农业 ,是人类最直接与森林生态系统的相互作用 ,成为人类对热带山区生态环境适应的一种生存方式 ,具有悠久的历史[1 ] 。随人口压力的增长 ,对粮食和其他农林产品需求的增加 ,迫使土地轮歇周期的缩短和在坡度较大的地方进行耕作 ,造成土壤侵蚀、养分流失、生物多样性减少 ,加上刀耕火种的粗放性、普遍性 ,使热带森林生态系统遭到严重破坏[1 1 ] 。有关西双版纳地区刀耕火种对植被演替[9,1 4 ] 、…