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421.
川中半自然型防护林演替过程中的物种多样性 总被引:3,自引:0,他引:3
四川中部绵阳官司河流域的半自然型林是长江中上游地区防护林的一个较典型类型。本文以它为研究对象,对群落的物种多样性及其在次生演替过程中的动态变化趋势进行了初步研究,并结合影响多样性的几个主要环境因子进行了相关性分析。结果表明:(1)现阶段该防护林的植物种类组成和群落结构均较简单,松、柏、栎混交的针阔叶林占绝对优势,其物种多样性较小,但随着群落次生演替的进展,各层次的多样性趋于增加;(2)用灰色系统理论的关联度分析方法研究群落的物种多样性与主要环境因子的相关性是可行的。经测定,研究区的土壤pH值,外界干扰度和土壤含水量等指标对防护林的物种多样性有显著的影响。图2表3参16 相似文献
422.
对评价森林资源生态环境效益的 2种方法进行了比较 ,阐述了这 2种方法的优缺点 ,通过案例分析可知 :森林资源环境效果评价法获得的评价值大 ,而意愿调查法的评价值小 ,并说明了导致这 2种方法评价值不同的原因。 相似文献
423.
本文探讨了森林生态系统中植物--土壤--大气CO2气体交换测定装置。本装置在草原生态系统植物群落光合作用测定装置基础上改进而来,适用于森林地带无交流电源,效能运输不便的地区,利用便携式CO2红外线分析仪和粉尘采样器替代气泵,具有经济,轻便,实用等特点。 相似文献
424.
425.
The overuse of rainforests in the last century and its consequences necessitate a rethinking of logging policies. To this end models have been developed to simulate rainforest dynamics and to allow optional management strategies to be evaluated. Parameterisation of presently existing models for a certain site needs a lot of work, thus the parameterisation effort is too high to apply the models to a wide range of rainforests. Hence, in this paper we introduce the simplified model FORREG using the knowledge we have gained from a more complex model, FORMIX3-Q. 相似文献
426.
427.
Effects of New Forestry Practices on Rare Epiphytic Macrolichens 总被引:5,自引:0,他引:5
JUHA PYKÄLÄ 《Conservation biology》2004,18(3):831-838
Abstract: The preservation of key habitats is included in modern forest-management practices as one of the main means to preserve biodiversity in northern European production forests. I examined the distribution patterns and persistence of occurrence of rare epiphytic macrolichens in a predominantly unprotected forest landscape with an area of 278 km2 in southern Finland. Occurrence data of macrolichens in two key habitats, rock outcrops and mires, were compared with data from production forests. The density of populations of rare macrolichens was 50-fold higher on rock outcrops and 25-fold higher on mires than in production forests. Most rare species of epiphytic macrolichens were found only in key habitats. In modern, intensively managed forest landscapes, rock outcrops appeared to represent the main habitats for rare macrolichens as a result of the long-term continuity of old trees. Most macrolichen occurrences represented very small populations with a high extinction risk. Of the populations found in 1989–1995 in key habitats, 51% had disappeared, by 2000–2001, mainly as a result of forestry activities. The disappearance of populations significantly exceeded the rate of establishment of new populations. My results emphasize the importance of key habitats for declining forest species. There is also a need to improve and sharpen the guidelines for delimiting and managing key habitats in order to halt the continued decline of epiphytic macrolichens. 相似文献
428.
扁刺栲-华木荷群系次生林林下物种多样性分析 总被引:6,自引:0,他引:6
对四川中亚热带扁刺栲(Castanopsis platyacantha)—华木荷(Schima sinensis)群系人工杉木林、水杉林、日本落叶松林和天然次生林林下植物进行了群落调查和物种多样性分析。结果表明:(1)杉木林、水杉林、日本落叶松林和次生扁刺栲—华木荷林(20a)的物种丰富度分别为62,59,53和32;Simpson多样性指数分别为7.95,7.08,9.24和5.38;Shannon—Wiener多样性指数分别为3.67,3.3l,3.64和2.46。(2)人工林林下植物群落之间的群落系数和相似度系数分别为0.45~0.60和0.62~0.82;人工林林下植物群落与次生阔叶林林下植物群落之间的群落系数和相似度系数分别为0.19~0.53和0.55~0.77。(3)人工林林下物种多样性比次生林高的主要原因可能是风倒木和站干死木导致人工林乔木层郁闭度减小,增加了林下的光照,从而改蛮了林下的微生境。表6参19。 相似文献
429.
The Northwest Forest Plan as a Model for Broad-Scale Ecosystem Management: a Social Perspective 总被引:1,自引:0,他引:1
SUSAN CHARNLEY 《Conservation biology》2006,20(2):330-340
Abstract: I evaluated the Northwest Forest Plan as a model for ecosystem management to achieve social and economic goals in communities located around federal forests in the U.S. Pacific Northwest. My assessment is based on the results of socioeconomic monitoring conducted to evaluate progress in achieving the plan's goals during its first 10 years. The assessment criteria I used related to economic development and social justice. The Northwest Forest Plan incorporated economic development and social justice goals in its design. Socioeconomic monitoring results indicate that plan implementation to achieve those goals met with mixed success, however. I hypothesize there are two important reasons the plan's socioeconomic goals were not fully met: some of the key assumptions underlying the implementation strategies were flawed and agency institutional capacity to achieve the goals was limited. To improve broad-scale ecosystem management in the future, decision makers should ensure that natural-resource management policies are socially acceptable; land-management agencies have the institutional capacity to achieve their management goals; and social and economic management goals (and the strategies for implementing them) are based on accurate assumptions about the relations between the resources being managed and well-being in local communities. One of the difficulties of incorporating economic development and social justice goals in conservation initiatives is finding ways to link conservation behavior and development activities. From a social perspective, the Northwest Forest Plan as a model for ecosystem management is perhaps most valuable in its attempt to link the biophysical and socioeconomic goals of forest management by creating high-quality jobs for residents of forest communities in forest stewardship and ecosystem management work, thereby contributing to conservation. 相似文献
430.
A methodology for simulating climate change impacts on tree growth was introduced into a statistical growth and yield model in relation to variations in site fertility and location implemented with current temperature sum. This was based on a procedure in which the relative enhancement in stem volume growth was calculated from short-term runs of a physiological simulation model for Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) Karst.) and silver birch (Betula pendula Roth.) stands. These simulations were made for a set of stands with species-specific variations in stand characteristics, location and fertility type first in current climatic conditions and then in different combinations of CO2 and temperature elevations. Based on these simulations, the relative enhancement of volume growth induced by the climate change (relative scenario effect, RSEv) was calculated and modelled in relation to: (i) CO2 and temperature elevation, stand density and the competition status of the tree in its stand, and (ii) variations in site fertility type and current temperature sum of a stand. Finally, these transfer functions for RSEv were applied to adapt the stem volume growth in the statistical growth and yield model to reflect the response to climate change. 相似文献