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71.
矮杨梅生境及群落学特征   总被引:1,自引:0,他引:1  
矮杨梅(Myrica nana Cheval.)隶属杨梅科杨梅属,常绿灌木。仅自然分布于我国西部部分省区.为我国特有的窄生态幅植物。本文对矮杨梅的地理分布、生境、群落特征进行了考查。分析了生境对该物种生长、分布的影响;提出了种内变异问题。以期丰富对矮杨梅这一物种的认识。  相似文献   
72.
宝天曼植物群落物种多样性研究   总被引:33,自引:5,他引:33  
对宝天曼保护区植物群落物种多样性进行了研究。结果表明 ,物种丰富度指数、多样性指数和均匀度指数在群落梯度上的分布趋势基本一致 ,较好地反映了不同植物群落类型在物种组成方面的差异。草本层物种丰富度指数明显高于乔木层和灌木层 ,草本层物种丰富度指数在群落梯度上的变异最大 ,灌木层次之 ,乔木层最小。乔木层物种多样性指数小于灌木层和草本层 ,草本层和乔木层物种多样性指数在群落梯度上的变异程度明显大于灌木层。灌木层物种均匀度指数大于乔木层和草本层 ,草本层和乔木层均匀度指数在群落梯度上的变异程度大于灌木层。物种丰富度指数和多样性指数的较大值出现在高海拔和低海拔群落 ,较小值多出现在中等海拔群落。物种均匀度指数的较小值多出现在中等海拔群落 ,但其较大值在各海拔群落都有分布。草本层物种丰富度指数和多样性指数的较高值多分布在低海拔群落 ,较小值多分布在中等海拔群落 ;乔木层和灌木层的各种指数以及草本层的物种均匀度指数在海拔梯度上的分布规律不明显  相似文献   
73.
Environmental factors, such as global solar radiation, wind speed, air temperature, humidity, and CO2 concentration, were measured above and within the canopy of a tropical rainforest in Lambir Hills National Park, Sarawak, Malaysia. Few data concerning the environment of this forest have been reported. Intensive observations were carried out in 1998, 1999, and 2000 with the following results: (1) The fraction of global solar radiation reaching the upper layer of the canopy varied with global solar radiation above the canopy. Even though the global solar radiation above the canopy fluctuated, the fraction of that reaching the lower canopy and the ground was constantly approximately 5%. (2) The fraction of wind speed reaching each layer of the canopy increased with wind speed above the canopy. Little wind was usually present at the lower canopy. (3) The daytime air temperature at the canopy top was higher than that near the ground. The maximum difference between the air temperature at the canopy top and that at the ground was about 5°C, and the diurnal temperature ranges at the canopy top and those at the ground were about 8°C and about 5°C, respectively. The highest daytime water vapor pressure occurred within the canopy and particularly near the ground. Vertical gradients of water vapor pressure during the day were steep, probably because of high transpiration. (4) In the 1998 observation the minimum and the maximum CO2 concentrations were 360 ppm in the day and 450 ppm at night, while in the 2000 observation the minimum and the maximum CO2 concentrations were 350 ppm in the day and 540 ppm at night. The higher CO2 concentration in the daytime and the lower concentration at night observed during the 1998 observation period were probably due to reduced photosynthesis and soil respiration caused by exceptional dry conditions during the observation period.  相似文献   
74.
在对福建永春油杉天然林群落系统调查的基础上,对该群落的植物区系成分、结构特征和物种多样性进行了研究.结果表明:该群落共有维管束植物131种,隶属于60科111属 .包括藤本植物在内的高位芽植物占总数的71.75%,区系组成以泛热带成分较高 ,群落结构较为复杂.物种多样性指数(Shannon-Wiener指数)以草本层最高,为2.245 1.  相似文献   
75.
An assessment was made of the attributes of People’s Organisations (POs) and of the institutional viability of Community-Based Forest Management (CBFM) programs in three project sites in the Philippines. In CBFM, the capacity of People’s Organisations, as de facto managers of forest resources, is being developed by non-government organisations under the guidance of local government units (LGUs) and the Department of Environment and Natural Resources (DENR). A survey was conducted of community members (case informants) and members of the various agencies (key informants) to ascertain the characteristics of successful POs and the relationship between these characteristics and the viability of CBFM. Although commendable contributions have been made to the forest management capability of POs, their standard of living and environmental conditions, there are also many instances in which institutional conflict among stakeholders is apparent. The great challenge for the various stakeholders is to orchestrate their differing interests so as to address successfully the critical issues of the low socioeconomic status of PO members, corruption, lack of transparency and accountability of the organisations involved, loss of interest of PO members in project activities, lack of technical assistance, loss of credibility of the DENR, and lack of equitable benefit sharing.  相似文献   
76.
The aim of our study was to characterize the structure and regeneration dynamics of dominant tree species along altitudinal gradient in dry valley slopes of the Bhutan Himalaya. In the typical dry valley slopes of west-central Bhutan, we analyzed forest stratification, tree crown projection, and population structure from lower dry valley bottom (1520 m a.s.l.) to upper humid ridge top (3370 m a.s.l.) across five major forest types: i.e. (1) dry pine forest with Pinus roxburghii as a dominant species; (2) mixed broad-leaved forest with Quercus lanata (evergreen), Quercus griffithii, (deciduous), and Rhododendron arboreum (evergreen) as major canopy species; (3) evergreen broad-leaved forest dominated by Quercus semecarpifolia, Quercus glauca and Quercus oxyodon; (4) cool conifer forest dominated by Abies densa and Tsuga dumosa; (5) cold conifer forest with A. densa and Juniperus recurva as dominants. In general, regeneration pattern of major dominant species shifted from inverse-J (lower altitudes), to sporadic (mid-altitudes), and to uni-modal type (upper altitudes) corresponding to three regeneration trends: (1) invasive at the lower, warm, dry forest under relatively strong human disturbances; (2) stable/balanced at the mid-altitude, in a relatively stable, mature moist evergreen broad-leaved forest with gap regeneration; and (3) poor/low regeneration at the upper, cool, humid conifer forest with a continuously cattle-grazed understory. Overall, regeneration patterns were balanced in all forest types, however care should be taken to prevent excessive exploitation of dry pine forest of lower valley bottom, and to control cattle grazing at higher altitudes. Our findings can be incorporated into management plans for sustainable management and conservation of mountain forests.  相似文献   
77.
海南霸王岭热带山地雨林森林循环与群落特征研究   总被引:6,自引:0,他引:6  
以海南霸王岭1hm^2热带山地雨林的网格样方调查数据为基础,首先对全林分的群落特征进行了分析,然后以森林循环理论为指导,研究了热带山地雨林的种群与群落特征。结果表明:热带山地雨林中不同生活型的树种在利用垂直和水平生态资源上是相对分离的,绝大部分的灌木或小乔木树种的水平生态位宽度较大,垂直生态位宽度较小,中、大乔木则正好相反,而那些低密度、稀有种的生态位宽度最小。随森林循环过程的进行,各树种在不同阶段斑块内出现的频度也会发生相应的变化。霸王岭热带山地雨林中占优势的乔灌木树种大都呈聚集分布的格局,个体数中等的树种大都呈均匀分布的格局,而那些个体数少的低密度种则大都呈随机分布的格局。随着森林循环过程的推进,每个树种所拥有的个体数和所占据的面积是逐渐减少的。森林循环不同阶段内的树种数随着个体数的增加呈现出逐渐减少的总趋势,尤其是由单个体和双个体所对应的物种数较多,3个以上个体对应的树种数则呈现出明显的下降。不同斑块之间组成相似性的大小在一定程度上表明了热带山地雨林森林循环斑块动态的连续性,相邻阶段斑块之间的相似性大于不相邻阶段斑块。以森林循环阶段为基础计算的生态位宽度表明,热带山地雨林中大部分低密度的树种或只集中分布在森林循环的少数阶段斑块内的树种对不同阶段斑块的生态资源利用较少,而那些在森林循环的不同阶段都出现,且个体数或断面积中等的树种,对森林循环不同阶段斑块的生态资源利用较大。  相似文献   
78.
社区林业及其在四川的实践   总被引:2,自引:4,他引:2  
本文探讨了社区林业的产生和发展过程,介绍了国内外社区林业发展的现状和经验,分析了四川的社区林业发展和取得较好效果的原因,指出了四川社区林业未来发展的目标:一是做好社区发展服务和为生态建设服务的工作;二是处理好社区林业发展与国家生态工程建设的关系;三是加大主区林业传播推广力度。  相似文献   
79.
In order to analyze the effects of the temperature gradient on moisture movement during the highly intensive microwave-vacuum drying, thermal diffusion of Masson pine wood was studied. Internal distribution of temperature and moisture in Masson pine samples sealed by epoxy resin and aluminum foil was measured, the magnitude of thermal diffusion was calculated and the influencing factors of thermal diffusion were discussed. Results showed that with the transfer of moisture toward the low temperature in wood, opposite temperature and moisture gradient occurred. The initial moisture content (MC), temperature and time are important factors affecting this process; the thermal diffusion is in proportion to wood temperature, its initial moisture and time. The temperature and distance from hot surface is strongly linearly correlated, and the relationship between MCs at different locations and distance from the hot end surface changes from logarithmically form to exponentially form with the increase in experimental time.  相似文献   
80.
参与式方法在退耕还林规划中的应用   总被引:3,自引:2,他引:3  
本文介绍了应用社区林业参与式方法在棉竹市、天全县、筠连县的退耕还林(草)试点工程中,探索参与式规则和实施活动。经过开展研究、走访农户、退耕还林地实地踏查等探索,认为在退耕还林(草)工程中应用参与式的方法进行规划很有必要。初步提出了开展参与式规划的八个步骤:一是初步调查确定项目,二是对农户的宣传发动和咨询服务,三是农户意愿和基本情况调查,四是计划阶段,五是作业设计,六是项目实施,七是检查验收和政策兑现,八是监测评估。  相似文献   
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