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51.
家庭林场经营模式的优点,除了创新经营管理体制,解放农村生产力,调动广大林农的生产经营积极性,促进林农脱贫致富外,还在于该模式内涵丰富的生态文明价值理念,能够将生态文明价值观在代际间传递延续,指导生产实践,保护生态环境,实现永续发展,这对促进生态文明建设、构建美丽中国具有重大的现实作用和深远的影响意义。本研究在阐明家庭林场内涵丰富的生态文明价值理念的基础上,阐释了发展家庭林场的经济、社会和生态效益,并针对目前家庭林场发展存在的问题提出对策建议。  相似文献   
52.
用溶液培养法研究了741杨的缺素症状和最适pH值。观察了5种大量元素的缺素症状,缺素对苗木生长和生物量的抑制顺序为N>K>P>Mg>Fe.缺素对叶绿素含量的抑制顺序为N>Fe>K>Mg>P.缺素会降低叶内其它必需元素的含量。741杨苗木生长的最适pH值为4.84~7.03,适应pH值为7.46~8.22,它能在pH4.84~8.22的范围内正常生长,在极限pH值(pH4和pH10)生长受抑制较大,但未出现坏死等症状。  相似文献   
53.
Where natural production capacity permits, modern silvicultural management in Central Europe frequently aims at the development of mixed broadleaved stands, instead of pure European beech (Fagus sylvatica) stands. It is crucial to study the effects of these tree-layer diversity variations on herb-layer vegetation, since herb-layer vegetation contributes significantly to ecosystem functioning in forests. In Hainich National Park (Thuringia, Germany), we conducted observational research in deciduous stands to investigate whether herb-layer diversity was related to canopy-layer diversity, and to ascertain possible causal mechanisms. We found that herb-layer vegetation of deciduous forest stands rich in canopy species appeared to be more diverse than herb-layer vegetation of beech-dominated stands. We surmise that herbaceous understorey diversity was indirectly influenced by canopy tree species through the medium of the altered environmental factors soil pH and litter layer thickness. Apparently, lower beech proportion had a more profound effect than the number of secondary tree species. There were no correlations between herb-layer diversity and light transmissibility of the canopy layer, indicating that the light factor was not crucial for herb-layer diversity. At least for the Hainich research sites, our results indicated that small-scale light and soil heterogeneity is insignificant for herb-layer diversity. We found several herb-layer species whose occurrence was particularly correlated with tree-layer diversity and environmental factors. Remarkably, all species positively correlated with soil pH were important for the phytosociological classification of the research sites. Beech-dominated research sites showed high tree-layer volumes, whereas research sites with high tree-layer diversity tended to feature lower tree-layer volumes. These findings could be the result of differing former silvicultural systems and varying soil clay contents affecting tree species composition. In contrast, herb-layer biomass was positively correlated with tree-layer diversity. Herb-layer productivity might be promoted in more diverse research sites by increased nutrient supply and base saturation. It is also possible that greater beech proportion interfered with herb-layer productivity. However, herb-layer biomass was also positively correlated with herb-layer diversity. Hence, our study hints that positive diversity-functioning relationships might occur in the herb-layer of the deciduous forest under investigation.  相似文献   
54.
分析与评价一个地区森林的间接经济价值是当前生态经济学研究的重要课题。根据森林生态系统服务价值的计算方法,估算出恩施州森林生态系统间接经济价值为9.948 1×108元/年,其大小顺序依次为:保护生物多样性>固CO2释O2>育土保肥>水土保持>净化空气。评估森林间接经济价值旨在强调森林的生态功能,促进以可持续发展战略为重点的科学发展观,为核算绿色GDP奠定基础。  相似文献   
55.
1 INTRODUCTIONUrban forestry means different things to differentpeople, depending on one’s perspective. Some peopleview urban forestry in terms of economic values,rather than cultural or social values, whereas othersmay perceive it in terms of all three types of values.As such, the management of urban green spaces maybe tailored to suchvalues. To Kuchelmeisterand TREECITY (1998), urban greening and urban forestry aretwo different fields altogether. They referred to urbangreening as t…  相似文献   
56.
森林社会效益价值评价研究综述   总被引:11,自引:2,他引:11  
对森林社会效益的认识可以追溯到18世纪的德国,主要是由于对森林美学的研究而引起的,其评价研究始于20世纪40年代.对森林社会效益,目前国内外还没有形成一个明确的、权威的定义,多数定义主要是对森林社会效益内容的描述、列举,还缺乏一个明确的、本质性的界定,还需要从经济学、生态学、环境经济学、林学和社会学等角度进行探索、研究.对评价内容也没有形成统一的认识,也处在认识、研究之中.比较认同的评价内容是森林提供的就业机会、森林游憩和森林的科学、文化、历史价值.森林社会效益的价值评价方法的研究,更是一个复杂的系统工程,目前,对森林提供的就业机会主要采用投入产出法、指数法评价;对森林游憩价值主要采用旅行费用法等评价;对森林科学、文化、历史价值主要采用指标评价法、条件价值法和综合模型评价法等评价.  相似文献   
57.
ABSTRACT

French bean (Phaseolus vulgaris L.) cv. ‘Anupama’ was grown in refined sand at variable levels of cobalt (Co), i.e., 0.0001 (control), 0.05, 0.10, 0.20, 0.40, and 0.50 mM, supplied as cobalt sulfate. The symptoms of excess Co (0.50 mM) appeared at day 35. In addition to growth depression, the young leaves developed chlorosis from the apex leading toward the base; the chlorosis intensified, changed to necrosis, and the infected leaves dried and withered. Under excess Co (> 0.0001 mM), the flowers produced were fewer in number, smaller, and many failed to mature, leading to lower seed yield. Excess Co (> 0.0001 mM) decreased the biomass, seed yield (number and weight), concentration of chlorophyll, Hill reaction activity, and activity of catalase, and deteriorated the quality of produce (sugars, starch, and protein nitrogen (N)), but it increased the concentration of phenols and activity of certain enzymes, i.e., peroxidase, ribonuclease, and acid phosphatase. The concentration of Co in various parts of French bean increased with an increase in Co supply and that of iron (Fe) decreased concomitantly. The values of threshold of toxicity and toxicity of Co were 26 and 72 μg g?1 in young leaves of French bean, respectively.  相似文献   
58.
Farmers' relationship with nature isdetermined by the significance of agriculturefor human beings. When agriculture is definedas human activity that uses renewable naturalresources and aims to produce usable food andfiber products, agriculture is explicitlydefined as production. Farmers' relationshipwith nature is based on the principle ofproduction. This article discusses thecontradiction between the peasant values ofprotection of nature that many farmers inFinland still have and the environmental harmtheir production-oriented farming style causes.When farmers interpret their farming practicesas harmonious co-operation with nature, it isdifficult for them to see the polluting effectsof their work. Paul B. Thompson's suggestionthat three religious–philosophical doctrines(hard work, the doctrine of grace, and the mythof garden) have made it easy for farmers toadopt productionist farming strategy is used asa framework to interpret farmers' narrativesconcerning their relationship with nature. Theresearch is qualitative and biographical. Thedata include life stories and biographicaltexts farmers wrote for a competition in1997.  相似文献   
59.
胶东半岛棕壤区域主要农业土壤中元素环境背景值   总被引:1,自引:0,他引:1  
在胶东半岛棕壤区域共采集435个上样,测定了铜、锌、铅、镉、鎳、砷、鉻、汞8种元素;土壤剖面各层加测了钛元素,共取得4459个数据。对所取得的数据进行数理統计,获得本区粗骨棕壤、棕壤和草甸棕壤三个亞类的8种元素环境背景值。分析了該区域成上母质与土壤化学元素环境背景值的相关性和化学元素在剖面上的分布特征。  相似文献   
60.
党的语言是党的理论、路线、方针、政策的逻辑表达。党的语言系统由主系统、次系统和外围系统三部分组成。党的语言系统的创新,既要符合语言及社会发展规律,又要尊重历史,与时俱进。  相似文献   
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