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81.
重大生态工程规划设计的理论探讨   总被引:1,自引:2,他引:1  
生态问题已成为阻碍我国经济社会可持续发展的主要屏障,解决生态问题的主要途径是实施生态治理工程。我国开展的诸多生态治理工程以退耕还林还草工程最为典型,由于相关理论研究长期滞后于生产实践需求导致该工程在推进过程中“边实施、边调整、边总结”。论文剖析了退耕还林还草工程不同阶段出现的问题以及国家采取的相应对策。通过理论分析指出生态问题是经济社会系统内部矛盾的外在表现,生态治理工程既要解决生态退化及危害,又要解决诱发生态问题的经济社会内部矛盾;生态工程设计需要生态学、经济学、社会学等相关学科的理论支撑。重大生态工程设计之初需要考虑技术储备、工程成本、成果稳定性(经济社会系统内部矛盾解决程度)、推广性、综合效益、政策及法律法规搭配等问题以达到“内外兼治”的效果,避免因“边实施、边调整、边总结”带来的工程风险和浪费,最终保障工程目标的实现。  相似文献   
82.
中国南方雨雪冰冻灾害受损森林植被研究进展   总被引:6,自引:0,他引:6  
2008年年初我国南方遭受了一场极为罕见的大范围持续低温雨雪冰冻极端气候灾害,这场灾害给我国人民的生产生活造成了重大损失,其中,林业受损尤为严重。我国学者针对受损森林生态系统进行了多方面的调查与研究。对现有的调查研究工作进行综述,重点概述了森林结构、功能和经济效益的受损状况,总结了天气条件、地理因素、树种及其生长情况,分析了林分特征等方面的森林受损机制以及受损森林的恢复与重建对策,对现有的研究在内容、水平及方向上的不足之处提出建议,以期对未来的相关研究提供帮助。  相似文献   
83.
官司河流域防护林景观结构及生态功能研究   总被引:3,自引:0,他引:3  
利用2005年度的IKONOS4卫片解译数据和2007年度小班调查资料,结合样地调查资料以及四川省林业科学研究院森林生态效益定位站(四川绵阳新桥)径流场的有关数据,对绵阳官司河流域的防护林体系景观结构及生态功能进行了分析。结果表明:该区域防护林景观中,以松柏混交林(Mixed Alnus—Cupressus forest)面积最大,占27.37%,其次是马尾松纯林(Pinus massoniana forest),占25.41%。栎柏混交林(Mixed Quercus-Cupressus forest)最少,只占0.96%。纯林面积明显大于混交林,前者比后者大45.31%。栎柏混交林、松柏栎混交林(Mixed Pinus-Cupressus—Quercus forest)最大斑块指数(LPI)、边缘密度(ED)和斑块密度(PD)较小,分布较为破碎。而马尾松纯林、松柏混交林和柏木纯林(Cupressus forest)分布较为集中。桤柏混交林(Mixed Alnus—Cupressus forest)和松柏混交林的散布与并列指数(IJI)较大,其空间关系较为复杂。栎柏混交林、柏木纯林的聚集度(A1)较小,斑块分散度大,连接睦较差;而桤柏混交林、松柏混交林的分散度较大,连接性较好。桤柏混交林、松柏混交林的形状指数(LSI)较小,形状分布较规则,而马尾松纯林、柏木纯林的形状指数较大,形状较复杂。从不同景观类型林下灌草层的生物多样性指数可知,松柏混交林、栎柏混交林的灌草多样性指数均较大,而马尾松纯林、柏木纯林则较小。从保持水土功能来看:桤柏混交林、松柏混交林的水土保持效果优于柏木纯林、马尾松纯林,桤柏混交林的水土保持效果优于松柏混交林。因此,对长江防护林进行空间结构调整,应多采用混交林模式,针阔混交林代替针针混交,乔灌草结合,调整合理的密度,使防护林景观的生态功能更好地发挥。  相似文献   
84.
Sacred natural sites (SNS) are instances of biocultural landscapes protected for spiritual motives. These sites frequently host important biological values in areas of Asia and Africa, where traditional resource management is still upheld by local communities. In contrast, the biodiversity value of SNS has hardly been quantitatively tested in Western contexts, where customs and traditions have relatively lost importance due to modernization and secularization. To assess whether SNS in Western contexts retain value for biodiversity, we studied plant species composition at 30 SNS in Central Italy and compared them with a paired set of similar but not sacred reference sites. We demonstrate that SNS are important for conserving stands of large trees and habitat heterogeneity across different land-cover types. Further, SNS harbor higher plant species richness and a more valuable plant species pool, and significantly contribute to diversity at the landscape scale. We suggest that these patterns are related not only to pre-existent features, but also to traditional management. Conservation of SNS should take into account these specificities, and their cultural as well as biological values, by supporting the continuation of traditional management practices.

Electronic supplementary material

The online version of this article (doi:10.1007/s13280-015-0738-5) contains supplementary material, which is available to authorized users.  相似文献   
85.
The composition of bryophytes in forests of the Ufa Plateau has been studied. The results obtained by ordination methods show that the coverage of epigeic mosses decreases with an increase in tree stand density and proportion of broadleaf tree species as well as in the coverage and average height of herbaceous layer. The main factors determining the distribution of epigeic mosses are illumination level, soil fertility, and the degree of soil development.  相似文献   
86.
Background, aim and scope  Chlorine is an abundant element, commonly occurring in nature either as chloride ions or as chlorinated organic compounds (OCls). Chlorinated organic substances were long considered purely anthropogenic products; however, they are, in addition, a commonly occurring and important part of natural ecosystems. Formation of OCls may affect the degradation of soil organic matter (SOM) and thus the carbon cycle with implications for the ability of forest soils to sequester carbon, whilst the occurrence of potentially toxic OCls in groundwater aquifers is of concern with regard to water quality. It is thus important to understand the biogeochemical cycle of chlorine, both inorganic and organic, to get information about the relevant processes in the forest ecosystem and the effects on these from human activities, including forestry practices. A survey is given of processes in the soil of temperate and boreal forests, predominantly in Europe, including the participation of chlorine, and gaps in knowledge and the need for further work are discussed. Results  Chlorine is present as chloride ion and/or OCls in all compartments of temperate and boreal forest ecosystems. It contributes to the degradation of SOM, thus also affecting carbon sequestration in the forest soil. The most important source of chloride to coastal forest ecosystems is sea salt deposition, and volcanoes and coal burning can also be important sources. Locally, de-icing salt can be an important chloride input near major roads. In addition, anthropogenic sources of OCls are manifold. However, results also indicate the formation of chlorinated organics by microorganisms as an important source, together with natural abiotic formation. In fact, the soil pool of OCls seems to be a result of the balance between chlorination and degradation processes. Ecologically, organochlorines may function as antibiotics, signal substances and energy equivalents, in descending order of significance. Forest management practices can affect the chlorine cycle, although little is at present known about how. Discussion  The present data on the apparently considerable size of the pool of OCls indicate its importance for the functioning of the forest soil system and its stability, but factors controlling their formation, degradation and transport are not clearly understood. It would be useful to estimate the significance and rates of key processes to be able to judge the importance of OCls in SOM and litter degradation. Effects of forest management processes affecting SOM and chloride deposition are likely to affect OCls as well. Further standardisation and harmonisation of sampling and analytical procedures is necessary. Conclusions and perspectives  More work is necessary in order to understand and, if necessary, develop strategies for mitigating the environmental impact of OCls in temperate and boreal forest soils. This includes both intensified research, especially to understand the key processes of formation and degradation of chlorinated compounds, and monitoring of the substances in question in forest ecosystems. It is also important to understand the effect of various forest management techniques on OCls, as management can be used to produce desired effects.  相似文献   
87.
Reintroduction of imperiled native freshwater fish is becoming an increasingly important conservation tool amidst persistent anthropogenic pressures and new threats related to climate change. We summarized trends in native fish reintroductions in the current literature, identified predictors of reintroduction outcome, and devised recommendations for managers attempting future native fish reintroductions. We constructed random forest classifications using data from 260 published case studies of native fish reintroductions to estimate the effectiveness of variables in predicting reintroduction outcome. The outcome of each case was assigned as a success or failure on the basis of the author's perception of the outcome and on whether or not survival, spawning, or recruitment were documented during post‐reintroduction monitoring. Inadequately addressing the initial cause of decline was the best predictor of reintroduction failure. Variables associated with habitat (e.g., water quality, prey availability) were also good predictors of reintroduction outcomes, followed by variables associated with stocking (e.g., genetic diversity of stock source, duration of stocking event). Consideration of these variables by managers during the planning process may increase the likelihood for successful outcomes in future reintroduction attempts of native freshwater fish. Identificación de Correlaciones de Éxito y Fracaso de Reintroducciones de Peces de Nativos Agua Dulce  相似文献   
88.
黄土高原退耕还林(草)紧迫性地域分级论证   总被引:26,自引:2,他引:26  
退耕还林还草是治理黄土高原水土流失的有效措施。科学分析现有土地及其利用结构是退耕还林还草战略实施的重要保证。论文应用科学抽样数据资料,分析了黄土高原地区土地、耕地的坡度构成及其土地垦殖率等的区域差异特征,提出了黄土高原地区退耕还林(草)紧迫性地域分级。其结果可以为根据有限的资金,分区分批进行退耕,最大限度地保证粮食安全,并实现区域生态重建,为合理实施退耕提供科学依据。  相似文献   
89.
Ambient concentrations of ozone (O(3)) were measured and O(3) phytotoxicity to tobacco (Nicotiana tabacum L.) was demonstrated in several forest locations in Poland during a pilot study from July-October, 1991. At southern and central locations in Poland, the 24-hour average O(3) concentrations measured with a UV absorption photometer were in the range of 32-55 ppb, and the corresponding 1-hour maxima in the range of 39-83 ppb. At these locations longer period (four to fifteen days) average concentrations were determined using O(3) passive samplers (DGA, Inc.) and were reaching 60 ppb, while at Bialowieza in eastern Poland O(3) concentrations averaged less than 40 ppb. In Szarow, near the Niepolomice Forest in southern Poland, 1-hour O(3) maxima estimated from the data obtained using passive samplers were about 105 ppb in early September. At several locations in southern and central Poland, extensive O(3) injury was determined on O(3)-sensitive Bel W-3 tobacco plants; such injury did not occur in the Bialowieza Forest of eastern Poland. The results of this pilot study indicate that O(3) is present at phytotoxic levels in southern and central Poland.  相似文献   
90.
Tropical forests in countries like thePhilippines are important sources and sinks of carbon(C). The paper analyzes the contribution of Philippineforests in climate change mitigation. Since the 1500s,deforestation of 20.9 M ha (106 ha) of Philippineforests contributed 3.7 Pg (1015 g) of C to theatmosphere of which 2.6 Pg were released this century. At present, forest land uses store 1091 Tg(1012 g) of C and sequester 30.5 Tg C/yr whilereleasing 11.4 Tg C/yr through deforestation andharvesting. In the year 2015, it is expected that thetotal C storage will decline by 8% (1005 Tg) andtotal rate of C sequestration will increase by 17%(35.5 Tg/yr). This trend is due to the decline innatural forest area accompanied by an increase intree plantation area. We have shown that uncertaintyin national C estimates still exists because they arereadily affected by the source of biomass and Cdensity data. Philippine forests can act as C sink by:conserving existing C sinks, expanding C stocks, andsubstituting wood products for fossil fuels. Here weanalyze the possible implications of the provisions ofthe Kyoto Protocol to Philippine forests. Finally, wepresent current research and development efforts ontropical forests and climate change in the Philippinesto improve assessments of their role in the nations Cbudgets.  相似文献   
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