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31.
中国红树林生态系统的植物种类、多样性、功能及其保护   总被引:28,自引:0,他引:28  
本文从4个方面对中国红树林生态系统的植物进行论述:(1)中国红树林生态系统的红树植物、半红树植物、伴生植物、红树林区的大型藻类和浮游植物种类;(2)中国红树林生态系统植物的物种多样性、红树植物生理和形态适应的多样性、产物的多样性;(3)红树林的生态功能;(4)中国红树林生态系统的主要保护问题及其保护措施。  相似文献   
32.
Acidification is considered the most important one of the primary chemical stress factors that impact on freshwater ecosystems. In unpolluted freshwater systems, the primary controls on the degree of acidification are factors such as the geological substrate of the catchment area, the presence of organic acids secreted by vegetation in the river system, and equilibrium exchange of carbon dioxide with the atmosphere. Anthropogenic factors that can impact on the degree of acidification of freshwater systems include agricultural, mining and industrial activities, either through direct runoff into river systems or through deposition of atmospheric pollutants from these sources. The capacity factors alkalinity and acidity, which represent the acid- and base-neutralizing capacity (ANC and BCN) of an aqueous system, have been used as more reliable measures of the acidic character of freshwater systems than pH. Unlike pH, ANC and BNC are not affected by parameters such as temperature and pressure. Therefore, ANC has been employed as a predictor of biological status in critical load assessments. Freshwater systems with ANC's eq/L isμeq/L are considered sensitive to acidification, ANC=0 μbelow 150 commonly used as the predictor for fish species such as trout in lakes, and an eq/L as more realistic for streams. Acid-neutralizing capacity μANC value of 40 (ANC) can be determined by titration with a strong acid to a preselected equivalence point. Alternatively, it can be calculated as the difference between base cations ([BC]) and strong acid anions ([SAA]): ANC=[BC]- [SAA]=[Ca^2+]+[Mg^2+]+[Na^+]+[K^+]-[SO4^2-]-[NO3^-]-[Cl^-] To date, there has been no attempt to establish the ANC of South Africa's freshwater ecosystems or variability therein, despite the fact that long-term water quality monitoring data exist for all the parameters needed to calculate it according to the above equations. As a result, the relationship between the acid neutralizing capacity of freshwater ecosystems in South Africa and biodiversity factors, such as fish status, is unknown. Results of the first comprehensive (country-wide scale) evaluation of the acid neutralizing capacity of river systems in South Africa will be presented. Long-term monitoring data obtained from the Department of Water Affairs and Forestry (DWAF) from most of South Africa's river systems were used to establish geographic and temporal variabilities in ANC. The results show that the Berg and Breede River systems are most susceptible to acidification, and that geological substrate appears to explain most of the geographic variabilities observed.  相似文献   
33.
本文在分析巴西、印度等发展中国家和美国、德国等发达国家经济发展和生态环境建设经验的基础上,针对我国西部农村贫困和产业落后等影响经济、生态的制约因素,提出了西部经济发展与生态建设互动的一些有效途径,以期对最终实现西部经济发展与生态建设的双赢有所启示。  相似文献   
34.
Not only the nutritional status and biological activity but also the soil ecological functioning or soil health has been impacted profoundly by land degradation in the karst area of southwest China where the karst ecosystems are generally considered as extremely vulnerable to land degradation under intensified land-use changes. The objectives of this study are to elucidate the changes in overall soil quality by a holistic approach of soil nutritional, biological activity, and soil health indicators in the karst area as impacted by intense cultivation and vegetation degradation. Topsoil samples were collected on selected eco-tesserae in a sequence of land degradation in a karst area of southwest Guizhou in 2004. The soil nutrient pools of organic carbon (Corg), extractable extracellular carbon (Cext), total soil nitrogen (Nt), alkali-hydrolyzable nitrogen (Nah), total phosphorus (Pt), available phosphorus (Pa) were analyzed by wet soil chemistry. The soil biological properties were studied by means of measurements of microbial biomass carbon (both by fumigation–extraction, FE-Cmic, and by calculation from substrate-incubation respiration, SIR-Cmic) of respiration [respiration without addition of substrates, basal respiration (BR), and potential respiration (PR) with substrate-incubation] and of soil enzyme activities (invertase, urease, and alkaline phosphatase). Soil health status was assessed by simple indices of Cmic/Corg and BR/Cmic in conjunction with bacterial community structures determined by polymerase chain reaction and denaturing gradient gel electrophoresis. While the nutritional pool parameters, such as Corg and Cext, described basically the changes in soil life-supporting capacity with cultivation interference and vegetation declined, those parameters of biological activity such as FE-Cmic, SIR, and SIR-Cmic as well as bacterial community structures measured by molecular method evidenced well the changes in soil functioning for ecosystem health with the land degradation.  相似文献   
35.
Over the last two decades, China has introduced a series of agricultural and forestland use reforms, aiming to feed the largest population in the world and maintain ecological services locally and nationally. This paper studies the impacts of local government-driven reforestation on land use and land cover change, as well as its further impacts on livelihoods of upland farmers in Xizhuang watershed. An analysis of aerial photographs and ASTER satellite imagery from 1987 to 2002, respectively, showed that the forest has significantly increased at the expense of decreasing farmland. However, the monoculture reforestation of pine has caused both biophysical and socio-economic consequences. This case study also shows forestry decentralization in China remains incomplete. Land use and land cover change is also a political economic issue. Some of the reforms designed to protect forest resources have had a negative impact on rural livelihoods.  相似文献   
36.
东营市森林火险天气等级预报系统   总被引:2,自引:0,他引:2  
利用9210传输的气象资料,选用国家气象中心T106和HLAFS数值预报产品中的要素作为火险天气因子,根据森林火险原因,建立了东营市森林火险天气等级预报系统。  相似文献   
37.
抚仙湖是中国云南省的一个深水湖,连接着富营养化的浅水湖--星云湖,星云湖排放含绿藻的水进入抚仙湖。两湖位于省会昆明附近,由于地方文化、集约化农业、以及旅游业的发展,两湖已经富营养化。因为湖泊体积容量的级别差异,深水湖的富营养化几乎没被注意,抚仙湖秋季下层滞水带缺氧已经关注了20年,似乎下层滞水带是深水湖富营养化的指标或趋势。抚仙湖看起来目前情况尚好,可以说寡营养,然而,外界负荷是潜在的,且是以稳定的加速度进行的。在此对浅水湖富营养化的原因进行了讨论,包括在其它云南湖泊观察到富营养化的过程,再者,对两个连相湖的藻和蓝藻碎片的大小构成进行比照。为了与深水的抚仙湖状况进行比较,简略介绍了一个日本的深湖及其径流系统。其中,涡流和它的微生态系统,在两者中相关性很好。对于以涡流生态系统的见解判断微生态系统的深水湖富营养化问题将给予概括。  相似文献   
38.
The Global Rainforest Mapping (GRFM) project was initiated in 1995 and, through a dedicated data acquisition policy by the National Space Development Agency of Japan (NASDA), data acquisitions could be completed within a 1.5-year period, resulting in a spatially and temporally homogeneous coverage to contain the entire Amazon Basin from the Atlantic to the Pacific; Central America up to the Yucatan Peninsular in Mexico; equatorial Africa from Madagascar and Kenya in the east to Sierra Leone in the west; and Southeast Asia, including Papua New Guinea. To some extent, GRFM project is an international endeavor led by NASDA, with the goal of producing spatially and temporally contiguous Synthetic Aperture Radar (SAR) data sets over the tropical belt on the Earth by use of the JERS-1 L-band SAR, through the generation of semi-continental, 100m resolution, image mosaics. The GRFM project relies on extensive collaboration with the National Aeronautics and Space Administration (NASA), the Joint Research Center of the European Commission (JRC) and the Japanese Ministry of International Trade and Industry (MITI) for data acquisition, processing, validation and product generation. A science program is underway in parallel with product generation. This involves the agencies mentioned above, as well as a large number of international organizations, universities and individuals to perform field activities and data analysis at different levels.  相似文献   
39.
This paper analyses participatory forest policy and the ways it has influenced the relationships between people as it relates to the forest resource management. This case study was conducted in the middle hills of Nepal, and information was collected through direct observation, individual interviews, group discussion and secondary information analysis. It substantiates a few examples of how the community forestry programme can be used as a means to promote the participation of the women, the poor and dalit (untouchables) in forest resource management, as well as enhancing social justice and improving the forest resources in their locality. However, it also demonstrates that though the community forestry programme has a positive impact, it faces several constraints and challenges. The local Forest User Group is controlled by a few élites making the poor and disadvantaged vulnerable to further marginalization. The results of the case study strongly indicate that community forestry processes must address the political, economic and social needs of the forest users, and also provide a neutral platform on which the poor can present their cases.  相似文献   
40.
王云才  郭焕成 《山地学报》2003,21(3):265-271
北京市西部山区是因矿区开发使山地景观生态环境破坏的重点地区,在北京市生态环境整治与建设中具有十分重要的典型意义。不合理的煤炭资源开采导致了矿点密度大,采空塌陷区分布广,水资源急剧减少,水质污染严重,植被大规模遭破坏,水土流失严重,泥石流等灾害加重以及煤尘污染问题突出等一系列环境问题,呈现出山地生态系统遭受严重破坏的景观生态特征。本文以史家营为例,在典型调查的基础上,规划了景观生态环境恢复与重建区、种植养殖和观光生态农业示范区、果粮养殖生态农业区、林草放牧生态畜牧业示范区、生态旅游区的五个景观规划区域,探讨了生态型矿业、中低山特色生态农业和生态旅游发展的产业发展模式,并初步提出了景观生态整治的措施。  相似文献   
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