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1.
Parameters characterizing the activity of species in altitudinal zonal elements of the flora have been analyzed in the northern Baikal region. The results provide evidence for the weakening status of xerophilic species in the cenoflora of hemiboreal light coniferous forests of the class Rhytidio-Laricetea, which form the lower part of the forest belt bordering the steppe. This fact indicates that climate on the slopes of mountain ridges is becoming more humid. The increase in humidity may be explained by both progressing degradation of permafrost and increasing precipitation. On the other hand, no significant change has been observed in the cenoflora of mountain taiga forests of the class Vaccinio-Piceetea, which form the upper part of the forest belt.  相似文献   

2.
三峡库区森林植被恢复与可持续经营研究   总被引:17,自引:0,他引:17  
系统的野外调查数据和历史资料分析结果表明,三峡库区森林植被在空间上发展不均匀,无明显垂直分带,且分布分散,人为干扰严重。目前,在70多个植被类型中,森林类型占25个,江岸两侧海拔800 m以下地区森林已经很少。森林类型中,马尾松、柏木林的分布面积最大,并在许多疏林中成为主要树种,主要是飞播或人工种植。库区大于25°的坡耕地占耕地面积的17.5%。库区薪炭林仅能满足农村用能总需求量的10.78%。不合理的土地利用方式和对森林的不合理砍伐导致脆弱的土壤系统和森林生态系统的严重退化、生产力下降和严重的水土流失。库区土壤年侵蚀量达到2.9亿t。三峡工程建设和移民安置对库区森林生态系统的压力和影响将是长期的。调查结果同时表明,库区植物生物多样性丰富,植物种类在5 032种以上,而且乡土树种多。分析认为,只要抓住三峡工程建设的契机,紧密结合国家天然林保护和退耕还林工程建设,充分利用良好的生物学基础,科学地封山育林,分带逐步恢复,同时,因地制宜,退耕还林,发展森林能源,建设多目标复合和多种模式并存的林业经营体系,发展经济,就能从根本上改善森林经营环境,实现森林恢复,形成合理布局的水库森林防护系统,促进三峡库区生态环境建设和可持续发展。  相似文献   

3.
In the course of floristic studies in suburban forests near the city of Ivanovo, 206 species of vascular plants have been recorded, including 39 invasive species (18.9%). Information on specific features of distribution and activity of introduced species growing feral and accidental weeds in different forest types is presented. The most aggressive species are distinguished. Factors responsible for the invasion of alien species to forest cenoses and main tendencies in their dynamics are discussed.  相似文献   

4.
四川森林资源的可持续发展   总被引:4,自引:0,他引:4  
四川森林是我国三大林区之一“青藏高原东部林区”的重要组成部分,该区的森林植被是维系长江流域生态平衡的主要天然屏障。本区森林资源能否持续发展整关长江流域的生态安全。通过对四川森林资源的现状,特点和存在问题的分析表明,四川森林资源丰富,具很高的生物多样性,发展潜力大,是重要的生态屏障,但天然林多、人工林少、林地土中退化严重,资源分布不均,树种单一,森林结构不合理,引种与林副产品的开发也存在许多问题,经济、生态效益差,也是森林植被生态系统的脆弱区之一。要促进该省森林资源的可持续发展,保护其生物多样性,发挥潜力,增强生态屏障作用,必须走以保护为主,多渠道开发,经济与生态效益并重的综合发展之路。  相似文献   

5.
Motivated by a lack of scholarly attention to the substance of interpretive messages and materials, this study examines discursive aspects of interpretative brochures available at forest recreation and tourism sites in Vermont, United States. Directive statements that instruct and guide visitor experiences—and the discourses to which they contribute—were analyzed for content, form, and meaning. Across the interpretive brochures, four broad discourses were identified: the natural forest, the recreational forest, the productive forest, and the dependent forest. Consideration of intertextuality revealed a fifth, hybrid discourse that linked forests to meanings of Vermont as a distinctive place. The convergence of these discourses across the set of brochures gives insight into the ways interpretation serves to both direct individual visitor experiences at particular sites, and to influence the development of larger-scale place meanings.  相似文献   

6.
沱江源森林群落生物多样性垂直格局研究   总被引:6,自引:0,他引:6  
在野外样带调查的基础上,分析了沱江源头九顶山植被生物多样性随海拔而变化的规律,并简要分析了植被生物多样性垂直格局的影响因子。从河谷到林线,乔木占据群落上层,其郁闭度对林下灌草层群落发育影响很大,生物多样性体现出乔木层与灌草层的相互关系:乔木盖度大的群落其灌木和草本层稀疏,而盖度小的次生林和林线上的高海拔区域灌木和草本种类与个体都迅速增加。多样性指数Hill指数及N1、N2指数变化规律基本相似:林线以下乔木层多样性指数最高,灌木层次之,草本层多样性指数最小,尤其在中度海拔体现明显,海拔3 500 m以上,草本多样性指数最高,灌木次之,而乔木已退出竞争。  相似文献   

7.
The role of community-based plantation development in forest rehabilitation and poverty alleviation is a pressing issue for the government of Ghana. In this paper, we present an analysis of the prospects of a community-based plantation using taungya systems and indigenous trees as means to forest rehabilitation and livelihood improvement in Ghana. The project management strategies, communication process and incentive mechanism and their impact on local participation are discussed with the aim to recommending a mechanism through which local farmers can best be involved in rehabilitation of degraded sites in the future in Ghana. Data were collected through a survey using personal interviews of 431 farming households and ten key informants from ten communities living in scattered hamlets in and around forests reserves. The results show a high rate of local participation in project tree planting activities. Four years after the project’s initiation, about 250 ha of plantations had been established using twelve priority indigenous and one exotic species and farmers had indicated improvement in their farming practices and availability of food and forest products. Restoring forest quality as a timber resource and associated values, getting money, food stuff and timber and non-timber for domestic use, and having access to fertile land for farming were the top three issues prioritised by respondents as motivational factors for engaging in the project activities. Overall, this project demonstrates that reversing tropical forest degradation is possible. For this we need local involvement in tree domestication combined with activities that addresses livelihood needs and environmental concerns. This case also demonstrates the prospects of utilising indigenous tree species, not only exotic species that dominated tree planting in the past, for plantations and landscape rehabilitation in Ghana. Readers should send their comments on this paper to BhaskarNath@aol.com within 3 months of publication of this issue.  相似文献   

8.
在综合国内若干城市生态系统服务功能价值研究实例的基础上,构建了中国城市森林生态系统服务功能价值转移数据库和相应的Meta回归分析模型,对价值转移评估的影响因素进行了全面探讨,并对该模型的样本外价值转移的有效性进行了检验.研究结果表明:(1)中国城市森林生态系统服务功能的平均价值为5.868 万元/hm2·a,按照价值高低排序依次为:涵养水源>固碳释氧>保育土壤>生物多样性保护>净化大气环境>森林游憩>积累营养物质,且总体呈现出西部地区>东部地区>中部地区的区位分布特征;(2)城市森林生态系统服务功能的评估方法、类型因素,城市的区位、人口、经济因素和研究区面积因素都是影响城市森林生态系统服务功能价值变化的主要因素;(3)所构建的Meta价值转移模型的样本外价值转移的平均转移误差为18.54%,用于研究样本外价值转移估计的有效性较好.  相似文献   

9.
Grazing is the main land use in semi-arid regions of the world, and sustainable management practices are urgently needed to prevent their degradation. However, how different grazing intensities affect forest density and ecosystem functions is often not sufficiently understood to allow for management adaptations that safeguard the ecosystems and their functions in the long run. We assessed the aboveground carbon stocks and plant densities along a grazing gradient in the semi-arid seasonally dry tropical forest of north-eastern Brazil (Caatinga). On 45 study plots, we analysed the aboveground carbon stocks of the vegetation and determined forest density and recruitment as well as the population structure of the most abundant tree species. Grazing intensity was accounted for based on the weight of livestock droppings and classified as low, intermediate, or high. Mean aboveground carbon stock was 15.74?±?1.92 Mg ha?1 with trees and shrubs accounting for 89% of the total amount. Grazing at high intensities significantly reduced aboveground carbon stocks of herbs but not of other plant functional types. Instead, aboveground carbon stocks of trees and shrubs were negatively related to altitude above sea level, which is a proxy for reduced water availability along with lower anthropogenic impact. The population structure of the most common tree species was characterised by abundant recruitment, irrespective of grazing, whereas the recruitment of less frequent woody species was negatively affected by grazing. Overall, our data imply that grazing and forage management need to be adapted, including the reduction of free-roaming livestock and storage of fodder, to maintain carbon storage and forest density.  相似文献   

10.
The tropical deciduous forest in Bangladesh provides a substantial part of country’s forest and where the government has introduced participatory agroforestry landuse. This study examined management issues, financial viability, and environmental as well as social sustainability of this landuse system. The forest department allocated a plot of size 1.0 ha among the selected participants where they were allowed to practice agriculture as well as to plant tree species for 10 years. The financial indicators indicated that the landuse system was profitable and attractive [net present value (NPV) = US$ 17,710 and benefit-cost ratio (BCR) = 4.12]. It was also viable and suitable from the social and environmental stand points. The study concluded that under the present environmental and socio-economic scenario, this production system could be the best management tool that would earn money, stop forest degradation, and finally be a model of sustainable land management in an overpopulated country.  相似文献   

11.
The present study were made to estimate the avian fauna in terms of species richness and diversity and guild structure in forest habitats of Nainital district of Uttarakhand (350–2.450 m asl; 29° N). Field studies were conducted during January 2007 to December 2008. Total 43, 62 and 42 species were recorded from, Haldwani, Bhowali and Nainital forest habitats. Results indicate the species relationship between Bird species richness (BSR) and elevation sections (forest habitats) was not decline simultaneously along elevation; it shows hump shaped. BSR varied considerably along elevational gradient (43 to 62 species), was highest (62 species) at mid elevation (Mixed pine forest, 1.350–1.700 m asl) and decreased (20 species) at high elevation (Conifer forest, 1900–2450 m asl). It seems that mid altitude bulge is not caused by the presence of a group of mid altitude specialists but rather that there is an overlap in the distribution of low land and high elevation specialists at this altitude. A checklist of 79 avian species has also produced of Nainital district forest habitats. It is suggested that this study provide a base line structure for further study on species distribution in different forest habitats and along different elevation section in Western Himalayas (India).  相似文献   

12.
In Central Africa, important carbon stocks are stored in natural forest stands, while activities that modify the carbon storage occur in the forest landscape. Besides clean development mechanisms, the reduction of emission through deforestation and degradation (REDD) initiative is viewed as one way to mitigate climate change. Important forest habitat protection activities have already been implemented with the aim of conserving the biodiversity of the region in a sustainable manner. The main causes of land use changes in the region are small holder subsistence practices and logging activities. Agricultural production has low productivity levels and therefore investments in improved agricultural techniques can both reduce pressure on existing forests and perhaps allow for the reforestation of existing degraded lands. The logging industry is dominated by large, industrial scale, logging operations performing selective logging of specific species and large trees. The adoption of improved forest management practices can reduce the impact of such logging on the ecological integrity and carbon stocks. Some efforts to engage in the carbon market have begun in the region. Further research is needed into the types of projects that will most likely become successful in the region and what locations will offer the greatest benefits.  相似文献   

13.
Vegetation in the main types of forest landscapes in the south of the Far East has been analyzed with regard to the dependence of population density and spatial distribution of five wild ruminant species on the main parameters of phytomass. The results have shown that the majority of ruminant species at their current population density never suffer from insufficient food supply. A high population density of the sika deer (Cervus nippon) is the only factor that may cause degradation of vegetation in the study region. The present-day population density of ruminants in their habitats does not depend on the amount of phytomass and species diversity of forage plants. Conversely, there is a strong relationship between the highest population density of ruminants recorded during the past 50 years and the phytomass stock of forage plants in their habitats.  相似文献   

14.
Habitat loss and degradation are main global threats to biodiversity, and land-use changes in agriculture-dominated landscapes are crucial for an important portion of biodiversity, especially in Europe. We evaluated the effects of land-use changes (1954–2012) on a threatened species, the ortolan bunting, in an agricultural area crucial for its conservation in Italy. We built a distribution model for ortolan bunting in current landscapes and then re-projected it to past scenarios (1954 and 1999–2000). We evaluated the most important land-use changes occurred and estimated their effects on habitat suitability. Bunting occurrence was mostly affected by the extent of grassland (positively; used as foraging/breeding ground), shrubland (quadratic effect; perches/shelter), forest and urbanized land (negatively), and by solar radiation (positively) and slope (quadratic), consistent with other studies carried out especially in southern Europe. The potential distribution of the species was much larger in the past: the estimated decline in suitable habitat is 44–72 % (since 1999–2000/1954), coherent with historical data suggesting strong decline and contraction. Changes in suitability (1954–2012) were mostly associated with changes in the cover of forest, vineyards and abandoned areas (negatively), and shrubland (positively). Land-use/land-cover changes are the main drivers of species occurrence and of habitat decline. The heterogeneous landscape of hilly/low-mountain sites in this area, characterized by a mix of habitats offering complementary resources to ortolan buntings and other species of conservation concern, is currently threatened by abandonment and intensification, but its maintenance may be promoted by a correct definition of Rural Development Programme measures.  相似文献   

15.
Degradation of common pool resource (CPR) in developing countries has often been traced to high rate attached by poor people in discounting future flow of benefits, market failure, pressure on carrying capacity or sometimes property right failure. However, the concept of poorly enforced property right and particularly risk of eviction as a measure of insecurity of land tenure has not been adequately examined in the context of degradation of CPR. A game theoretic framework is developed where degradation of forest grazing land is explained in terms of changes in perceived risk of eviction from the encroached land. Logit regression is applied to empirically analyse the impact of perceived fear of reduced access and other variables on the state of degradation. For this purpose, a sample of seven villages is considered in tribal dominated region in West Bengal, India. It is observed that apart from a number of socio-economic variables like poverty, mutual trust and other incomes, perceived fear of eviction (represented as a dummy variable) arising from insecurity of forest land tenure, has a significant impact on forest degradation status in the study region.  相似文献   

16.
Pinus roxburghii (chir-pine) and Quercus leucothchophora (banj-oak) are dominant forests of mountainous part of the Uttarakhand Himalaya. The continued anthropogenic disturbance is opening the canopy, forming canopy gaps and as a result forest fragments are developing. Thus, the present study aims to analyze variations in species richness and vegetational parameters in relation to canopy gaps in forests. Total species richness was greater in open canopied forest compared to moderate and close canopied forests. In comparison between oak and pine forest, it was greater in oak forest while the proportion of common species was low between oak—pine forests. Mean species richness did not significantly vary from one canopy gap to another as well as in oak and pine dominated forest. This indicated that dominant forest types played an important role to form the community structure. The shrubs richness were greater in closed canopy and between the forests it was greater in pine forest. Tree and shrub density was low in open canopy while herb density was high in moderate canopy. Thus, this study indicated that the dominant canopy species play an important role in deciding the community structures especially the distribution of under canopy species. These parameters should be considered for conservation and maintenance of plant biodiversity of a region.  相似文献   

17.
In the present study total 21 forest stands on different aspects and locations (Hill base, mid slope and ridge top) on the slope were studied to assess the importance of these two parameters in supporting species regeneration and biodiversity in a mixed broadleaved forest between 380 and 850 m elevation in the Kumauau Himalayan region. A total of 36 tree species were recorded in the forest. In all aspects the tree, sapling and shrub richness was higher at hill base stands in comparison to mid slope and ridge top stand. Maximum tree richness (average across all aspects) was 9.7 and shrub richness was 9.3. Higher richness at hill base may be attributed to more soil moisture and deeper soils which accumulate the hill base where the slope steepness declines. The tree richness was higher in the northern aspect whereas southern aspect was more suitable for the shrub species. From the present study it becomes evident that the base of the hills can support higher biodiversity and are instrumental in supporting regeneration of several tree and shrub species in sal mixed broadleaved forest.  相似文献   

18.
庐山不同森林植被类型土壤特性及其健康评价   总被引:2,自引:0,他引:2  
土壤作为森林生态系统的一个重要因子,评价森林土壤健康状况对森林健康的维护经营以及森林系统功能的发挥具有重要意义。在系统调查和分析庐山8种森林植被类型土壤特性的基础上,评价指标分别从物种多样性以及不同的森林土壤特性中进行筛选,包括物种多样性系数、枯落物层厚度、腐殖质层厚度、土层厚度、容重、粘粒含量、有机质、p H值、阳离子交换量、全氮、水解氮、有效磷、速效钾、磷酸酶活性等指标,基于SPSS19.0软件对所获得数据进行差异性检验和相关分析,确定各项指标的权重,应用合适的土壤健康评分函数,将测得的指标值转换为对应指标的分值,最后通过加权综合法,计算其土壤健康指数,并对不同森林植被类型土壤健康状况进行评价。结果表明,8种森林植被类型下最终的土壤健康指数大小排序为:针阔混交林(0.78)常-落混交林(0.72)灌丛(0.69)常绿阔叶林(0.67)落叶阔叶林(0.64)竹林(0.59)马尾松林(0.53)黄山松林(0.46)。  相似文献   

19.
On the basis of syntaxonomy of primary forests in the Southern Ural region, an analysis of trends in the formation of their species diversity has been performed in regard to heat supply, soil moisture, and general soil richness. The roles of environmental factors have been estimated using Landolt’s scales. The results have shown that communities of forest classes Querco-Fagetea, Brachypodio-Betuletea, and Vaccinio-Piceetea differ in the trends of changes in species richness along gradients of the above factors. In communities of all these classes, species richness depends primarily on heat supply, with soil richness being the second most important factor.  相似文献   

20.
We compared differences in plant species diversity between conifer (Pinus tabulaeformis) plantations and natural secondary forests in the middle of the Loess plateau. The goal of the study was to examine the differences in the effect of stand development on species diversity and in species responses to changes between forest types and between forest layers. To clarify the effects of differences in forest management, we emphasized the functional types of plant species occurring in each forest type. The result as follow: (1) The H′ and S of tree layer were significantly lower in natural conifer forest than old conifer and secondary forest, but were not different compared with mid aged conifer forest. The H′ and S of shrub layer were significantly lower in mid aged conifer forest compared with other forest types. The H′ of herb layer showed no significant differences in the four forest types. The evenness index (J′) of tree layer of mid aged conifer forest was lower than other forest communities and its J′ of shrub layer was highest although its richness of shrub layer was lower than in the other forest types. (2) The analysis of β diversity index also indicated large differences between conifer plantations and natural forests. Although the tree layer species were similar in old plantation and natural conifer forests, they differed greatly between the natural conifer and secondary forests. The natural conifer and secondary forest species composition in shrub layer differed significantly from those in plantation and secondary plots. Tree species were significantly less common in plantations than in abandoned coppice forests. Species composition in the herb layer of different forest types was similar. (3) The management of P. tabulaeformis plantations alters plant species composition considerably; the number of sub tall-tree species is increased in old aged conifer forest, especially species dispersed by animals. Plantation management appears to affect ecological processes through seed dispersal. From the perspective of management, the change in the structure and composition of the canopy in plantations could affect the behavior of dispersers and regeneration.  相似文献   

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