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1.
上虞市海涂实验农场中心试验区的排水系统,能满足十年一遇的年最大24h降雨,两天内排出的要求。滨海盐土的地下水位高,农田基本建设除用浅、密的排水沟布置外,还应结合平整土地、发展灌溉以及适用的农、林技术等综合措施,才能达到治盐改土的效果。 相似文献
2.
DONOSO Leonito Acosta 《中国林业科技(英文版)》2005,(1)
The Luntiang Kamaynilaan Project (Metro ManilaGreening Project) launched in 1988 planted trees inmajor thoroughfares, center islands, school premisesand other idle public lands, was basically a governmenteffort. When the funds ran out, the project also fizzledout. In both projects however, it is evident that the keyfactor is peoples participation.Gaining lessons from the past two projects, thegovernment established a collaborative effort ofgovernment and non-government organizations. TheCl… 相似文献
3.
Mangroves as indicators of coastal change 总被引:2,自引:0,他引:2
In view of the unique biological characteristics of mangroves, it is interesting to assess the extent to which these ecosystems can be used as indicators of coastal change or sea-level rise. From recent studies of mangrove mortality at several locations (including Guiana, Gambia, Côte d'Ivoire, Kenya, India and Bangladesh), it appears that these coastal ecosystems are so specialized that any minor variation in their hydrological or tidal regimes causes noticeable mortality. Each species of mangrove (but particularly those belonging to the genera Rhizophora, Bruguiera, Sonneratia, Heritiera and Nypa) occurs in ecological conditions that approach its limit of tolerance with regard to salinity of the water and soil, as well as the inundation regime. If the duration of daily immersion were to be modified by tectonic, sedimentological or hydrological events, the species either readjusts to the new conditions or succumbs to unsuitable conditions. Consequently, the use of remote sensing data for mangrove ecosystems offers excellent potential as a tool for monitoring coastal change. 相似文献
4.
对澳门凼仔岛海岸山地防护林造林地 (8年生 )进行调查 ,分析了林分保存率、林分生长量、各树种平均胸径、平均树高、林分土壤肥力和林分植被变化情况。认为海岸山地防护林营造多树种阔叶混交林是一种值得研究推广的林分改造模式 相似文献
5.
6.
In the pastfew years, with speedilydeveloping of socialeconomy and continuously speeding up of urbanizationprogress in China, the problems of the ecologicalenvironment in urban area, such as air pollution, heat-island effect, dangers of wind and sand, and shortageof water resources, etc., have gradually been gravenessand become the focus issue concerned by citizens also.It has become the common understanding of mostcitizensthat ahealthy,secureand comfortableecologicalenvironment of human settl… 相似文献
7.
城市园林绿化现存问题、对策及其绿化植物配置原则 总被引:21,自引:4,他引:17
随着国民经济的不断发展,城市园林绿化已成为现代建设的重要内容。在归结上前城市园林绿化所存共性问题的基础上,针对城市园林绿化普遍存在的4方面问题,提出5点对策。 相似文献
8.
The interactive effects of rooting volume and nutrient availability in a skeletal soil medium designed to meet street tree and pavement needs were observed in a containerized experiment. Benjamin fig (Ficus benjamina L.) was grown in a stone-soil blended skeletal soil material (CU-Soil™) and compared to a loam soil. The same topsoil used as the soil component in the skeletal soil material was used as the sole component in the comparison soil-only treatment.Plants grown in the skeletal soil material had reduced leaf tissue N content and depressed growth compared with plants grown in non-diluted soil. No other mineral deficiencies were found. Leaf number, chlorophyll concentration, shoot weight, and root characteristics were all affected.Reduced growth from soil dilution could be offset by the provision of an enlarged rooting volume for root development. Large containers of skeletal soil were observed to have smaller root systems compared to equivalent net volumes of loam soil at the first two harvest dates of the study. By the end of the study, the large containers of skeletal soil were observed to have developed larger root systems compared to equivalent net volumes of loam soil; resulting in comparable leaf N levels and total plant dry matter. Plants in skeletal soil had lower shoot: root ratios at the end of the study. Investing resources to further root growth in times of nutrient shortages is a probable plant reaction as evidenced by differences in specific root length between treatments. The study allowed a method for directly partitioning the containerization effect by having equivalent amounts of soil over two volumes. 相似文献
9.
Urban trees can favorably affect factors underlying global warming by storing carbon and by reducing energy needs for cooling and heating buildings. To estimate carbon stored in roots and above-ground portions of trees, data was collected consisting of whole tree sampling of Amelanchier, Malus, Pyrus, and Syringa cultivars. Roots were excavated using an Air-Spade™. Regression analysis resulted in two equations for predicting total carbon storage based on height and diameter of trees up to 20 cm dbh: Y = 0.05836 (dbh2) for root carbon storage, and Y = 0.0305 (dbh2 × h)0.9499 for above-ground carbon storage, explaining 97% and 96% of the variation, respectively. Average carbon stored in roots of various cultivars ranged from 0.3 to 1.0 kg for smaller trees, those 3.8 to 6.4 cm dbh, to more than 10.4 kg for trees 14.0 cm to 19.7 cm dbh. Average total carbon stored by cultivars ranged from 1.7 to 3.6 kg for trees less than 6.4 cm dbh to 54.5 kg for trees larger than 14.0 cm. The data from these equations apply mainly to trees in nurseries and recently transplanted trees. Comparisons showed that above-ground estimates from previous studies using a sampling technique overestimated values obtained from actual above-ground weights. 相似文献
10.
基于不同尺度的干旱区城市景观生态研究--以陕西榆林市为例 总被引:6,自引:0,他引:6
从区域与城市两个尺度水平 ,对毛乌素沙漠南缘的榆林市城市景观进行研究认为 :在大尺度水平上 ,区域景观生态特征对城市景观特征具有一定的控制作用 ,而城市景观强大的功能流对区域景观产生干扰作用。城市景观的空间扩展与演化 ,既受区域景观特征的影响 ,也是区域景观演化的一个有机构成部分 ;在小尺度空间上 ,景观功能区、景观斑块与廊道的格局与功能 ,对城市景观格局动态以及维持城市景观多样的生态功能具有重要意义。在不同的利益追求下形成的景观文化 ,将深刻地影响到区域与城市景观演化的方向与过程。 相似文献