西双版纳热带山地雨林生物量研究

观测了西双版纳山地气候,建立了山地雨林生物量回归方程,调查了海拔1 100~1 820 m范围5块样地(面积0.16~0.25 hm2)的热带山地雨林生物量。结果表明,海拔1 105和1 610 m的年平均温度分别为20.1和16.6℃,年降雨量分别为1 659和2 011 mm,旱季(11~4月)降雨量分别为295和283mm,年平均相对湿度分别为81%和84%;5块样地生物量变化为256.4~368.6 t.hm-2,平均为312.6t.hm-2,其中乔木占97.1%、木质藤本占1.2%、幼树和灌木占1.3%、草本和幼苗占0.4%;采用热带季节雨林生物量回归方程估计山地雨林生物量,会使得总生物量以及树干和树根生物量高估38.3%~61.5%,树枝生物量低估7.6%~30.8%。可见,西双版纳山地海拔增加导致雨季降雨量增加,山地雨林生物量较热带季节雨林降低32.6%,季节雨林生物量方程不适用于山地雨林。     

Simulating the Long-term Response of Tropical Wet Forests to Fragmentation

In the coming decades, a large fraction of the world's tropical forests will be fragmented into remnants surrounded by secondary vegetation, land-use areas, or roads. It is important to develop integrative tools to monitor the evolution of these fragmented ecosystems. We used the individual-oriented and process-based forest growth simulator FORMIND2.0 to investigate the spatial and temporal effects on standing biomass and functional diversity of various intensities and patterns of fragmentation within a forest landscape. The simulator was calibrated for an old-growth wet forest in French Guiana, South America. We found that the standing biomass of forest remnants was reduced significantly compared to a similar area of nonfragmented forest. When fewer but larger remnants were created rather than many small ones, the total loss in biomass and the increase in the abundance of early-successional species were significantly reduced, confirming that edge effects dominate the functioning of forest remnants. We also performed simulations of secondary succession after the landscape had been abandoned. The simulated recovery time in those secondary forests depends on both the size of cleared area and the spatial pattern of the remnant forests. Received 30 January 2002; accepted 16 July 2002.     

Fragmentation Effects on Diversity of Wasp Community and Its Impact on Fig／Fig Wasp Interaction in Ficus racemosa L.

Habitat fragmentation usually results in alteration of species composition or biological communities. However, little is known about the effect of habitat fragmentation on the fig/fig wasp system.In this study, we compared the structure of a fig wasp community and the interaction between figs and fig wasps of Ficus racemosa L. in a primary forest, a locally fragmented forest and a highly fragmented forest.Our results show that, in the highly fragmented forest, the proportion of pollinator wasps is lower and the proportion of non-pollinator wasps is higher compared with the primary forest and locally fragmented forest. The proportion of fruits without pollinator wasps in mature fruits is also greatly increased in the highly fragmented forest. The proportion of galls in all female flowers increases in the highly fragmented forest, whereas the proportion of viable seeds does not change considerably. The disruption of groups of fig trees results in a decrease in pollinator wasps and even might result in the extinction of pollinator wasps in some extreme cases, which may transform the reciprocal interaction between figs and fig wasps into a parasite/host system. Such an effect may lead to the local extinction of this keystone plant resource of rain forests in the process of evolution, and thereby, may change the structure and function of the tropical rain forest.     

西双版纳片断化望天树林气候边缘效应比较研究

对西双版纳片断望天林树（Shorea chinensis)林林缘小气候的季节、水平变化进行了观测研究,对比分析了4个个不小雨林斑块（30hm^2,25hm^2,20hm^2,3hm^2)的小气候边缘效应。结果表明：各雨林斑块林缘均存在明显的小气候边缘效应,其中在干季晴天最为明显,且在上较小斑块林缘出现最高气温及气日较差高于林外的现象;干季,部分林缘小气候要素（最高气温、总辐射、净辐射、最小相对湿度）林缘与林内的差值均是高于或大于雨季的相应值,而地表最高温林缘与林内的差值则是雨季强于干季,各斑块相比,小气候边缘效应波及林内的深度在最大斑块达至最浅（25m),而在最小斑块达到最深（35m)呈现出小气候边缘效应及其影响深度随片继雨林斑块面积减小而增强及向林内进一步延伸的趋势。     

The fragmented Atlantic rain forest of Brazil: size, shape and distribution of forest fragments

The geographical characteristics of a total of 1839 forest fragments surrounded by sugar cane fields were studied in the Brazilian Atlantic rain forest region of the northeastern state of Pernambuco. The size and shape of the fragments as well as inter-fragment distances and the effects of varying edge width were examined using a geographical information system. The analyses show that the fragments are relatively small and close to each other. Approximately 48% of the rain forest fragments are <10 hectares, while only about 7% are >100 hectares. Forest fragments are close to each other, as fragments located 50m or less apart formed groups that included ca. 50% of the total forest area. At 350m inter-fragment distance, 98% of the rain forest area was included in groups of fragments. Due to the small size and irregular shape of the fragments, the total area of edge zone exceeds that of the interior habitat when the edge width is ca. 60m. At an edge width of 300m ca. 94% of the total fragment area is edge zone. For conservation purposes, ways of establishing networks of forest fragments connected by corridors and stepping stone fragments are demonstrated using GIS. Simulations using these techniques show that reforestation of sugar cane fields between the forest fragments would considerably increase the area of interior forest habitat and connectivity between fragments.     

云南热带季雨林及其与热带雨林植被的比较

在中国植物学文献中, 对热带季雨林的解释和运用是不一致的, 特别是易于把季雨林与热带雨林相混淆。季雨林是在具有明显干、湿季变化的热带季风气候下发育的一种热带落叶森林植被, 是介于热带雨林与热带稀树草原(savanna)之间的一个植被类型。云南的热带季雨林在分布生境、生态外貌特征、植物种类组成和地理成分构成上, 均与热带雨林有明显区别, 季雨林主要分布在海拔1 000 m以下的几大河流开阔河段两岸和河谷盆地, 其群落结构相对简单, 乔木一般仅有1至2层, 上层树种在干季落叶或上层及下层树种在干季都落叶; 在生活型组成上, 季雨林的木质藤本相对较少, 大高位芽植物及地上芽植物很少, 但地面芽植物很丰富, 地下芽植物和一年生植物也相对丰富; 在叶级和叶型特征上, 季雨林植物的小叶和复叶比例相对较高, 分别占到24%和44%; 在植物区系地理成分构成上, 季雨林的热带分布属合计也占绝对优势, 但以泛热带分布属的比例相对较高, 约占到总属数的30%, 热带亚洲至热带非洲分布属的比例也较高, 约占总属数的12%。季雨林的地理成分更为多样性, 起源与发展历史也更复杂和古老。     

片断化森林的边缘效应与自然保护区的设计管理

森林片断化引起了森林边缘物理环境与生物的变化。从森林边缘向林内,光辐射,温度、湿度、风等因素发生改变,这些反过 边缘上和边缘附近的生物产生极其重要的影响。有些研究表明,生物与非生物存在明显的边缘－核心的变化梯度,而有些则没有,除了影响边缘效应的客观因素（如边缘的取向、地势、年龄等）外,主观因素对这缘效应也有影响。边缘对生物与非生物的影响因片断化森林的面积、形状以及与其他森林片连接程度的不同而不同,     

片断化常绿阔叶林的植物多样性

由于人类活动的严重干扰,使得我国的常绿阔叶林基本上已片断化.对位于浙、闽、赣、皖交界山区的6个以甜槠和木荷为建群种的片断化常绿阔叶林的植物多样性进行了研究,结果表明:(1)6个片断化样点共有物种69～142种.其中乔木层共有24～39种,Simpson 指数(λ)为0.793 2～0.931 9,Shannon-Weiner指数(H')为2.410 8～3.201 8,Pielou均匀度指数(J)为0.667 6～0.813 2,Gleason指数(IG)为4.5816～8.209 8;灌木层共有45～120种,λ为0.830 9～0.955 8,H'为2.6257～3.7902,J为0.608 2～0.7903,IG为10.0216～17.2782;草本层共有6～23种,λ为0.5073～0.7639,H'为0.8783～1.8802,J为0.3822～0.5771,IG为0.9646～4.2871.(2)乔木层和灌木层分别在物种均匀度和丰富度上占有优势,此外,各片断化样点之间建群种比较类似,而林下灌木和草本种类则有明显差异.(3)人类干扰和片断化面积大小分别影响了乔木层和草本层的物种丰富度和多样性.(4)边缘效应明显,并且主要发生在林缘50m的范围内.从林缘到林内单位面积物种数根据片断化面积的大小分别呈现出上升和下降的格局,并且不同耐阴性的物种其分布密度表现出完全相反的特征.林缘0～50m的范围内,木本植物死亡率呈逐渐上升趋势,50m以后开始下降,林缘100m附近达到稳定.此外,林缘比林内具有更为丰富的藤本植物.