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991.
992.
Element cycling in the dominant plant community in the Alpine tundra zone of Changbai Mountains, China 总被引:1,自引:2,他引:1
Element cycling in the dominant plant communities including Rh. aureum, Rh. redowskianum and Vaccinium uliginosum in the Alpine tundra zone of Changbai Mountains in northeast China was studied. The results indicate that the amount of elements from litter decomposition was less than that of the plant uptake from soil, but that from plant uptake was higher than that in soil with mineralization process released. On the other hand, in the open system including precipitation input and soil leaching output, because of great number of elements from precipitation into the open system, the element cycling(except N, P) in the Alpine tundra ecosystem was in a dynamic balance. In this study, it was also found that different organ of plants had significant difference in accumulating elements. Ca, Mg, P and N were accumulated more obviously in leaves, while Fe was in roots. The degree of concentration of elements in different tissues of the same organ of the plants also was different, a higher concentration of Ca, Mg, P and N in mesophyll than in nerve but Fe was in a reversed order. The phenomenon indicates ( 1 ) a variety of biochemical functions of different elements, (2) the elements in mesophyll were with a shorter turnover period than those in nerve or fibre, but higher utilization rate for plant. Therefore, this study implies the significance of keeping element dynamic balance in the alpine tundra ecosystem of Changbai Mountains. 相似文献
993.
人类活动对生态系统服务功能的影响 总被引:50,自引:1,他引:50
生态系统服务功能是人类可持续发展的基础,但是人类在利用生态系统提供自然资源和生存环境两个方面的多种服务功能的同时,也在强烈影响生态系统的服务功能。除部分人类活动有利于生态系统服务功能的稳定与提高外,更多地则导致了一系列危及自身生存与发展的生态环境危机与灾难。目前,生态系统服务功能受到人类活动影响的后果已成为全球面临的日益突出的重大问题和人类社会共同关注的焦点,因而人类活动对生态系统服务功能的影响愈加受到人们的重视。论文介绍了生态系统服务功能的定义,阐述了生态系统服务功能的内涵,重点分析了人类活动影响生态系统服务功能的类型、人类活动对生态系统服务功能的影响及变化趋势。在此基础上,对尚待进一步研究的内容提出了建议。 相似文献
994.
荒漠生态系统服务功能及其价值研究 总被引:3,自引:0,他引:3
荒漠生态系统是整个生物明中分布较广的一个系统,是陆地生态系统中的一个重要的子系统,对这一广大区域的生态系统服务功能的正确认识,是经济发展和生态环境建设的重要依据.本文从生态系统服务功能的角度归纳了荒漠生态系统类型以及荒漠生态系统服务功能,主要有旅游服务、涵养水分和水源、保持水土、净化水体和空气、营养元素循环、物质生产、污染物降解、有机质、截留降水、涵养水分、土壤C的积累、农田生态系统服务、单位面积及区域生态系统服务价值等,以及评价荒漠生态系统服务功能价值的模型和方法,为正确评价荒漠生态系统服务功能提供依据. 相似文献
995.
996.
997.
生态系统服务价值评估研究进展及其在环境保护中的意义 总被引:2,自引:0,他引:2
介绍了生态系统服务功能价值的国内外研究进展。对研究趋势进行了分析,并对开展生态价值评价在环境保护中的意义进行了分析。 相似文献
998.
维生素对小麦生长及生理功能的调节作用研究进展 总被引:2,自引:0,他引:2
对植物来说,绝大多数维生素能够自身合成,但其含量在植物体内常常因为某些原因而偏低,从而导致了植物代谢受到一定程度的影响.因此外源维生素可以作为一类生长调节剂应用于一些农作物生产中.作为重要农作物的小麦,亦有应用外源维生素以调节其生长发育的例子.施用维生素具有促进小麦种子萌发和生长发育,调节一些生理代谢过程,提高小麦产量及品质等作用.表1参53 相似文献
999.
生态城市建设与城市超循环体系的构建 总被引:2,自引:0,他引:2
生态城市的设计、建设和评价,应从人、社会、自然3个层次和城市的结构、功能、协调和目标4个方面来进行定位,最终达到完善结构、提升功能、增进协调、城市优美和谐的目标。城市超循环体系是生态城市社会结构的重要组成部分,城市超循环体系的具有企业、产业、城市、区域4个基本层次,其循环体系、模式、功能和目标均各不相同。生态城市建设与城市超循环体系构建具有在理念上的一致性、结构和功能上的嵌套性、目标和发展机制上的同一性,在更深层次上表现为城市或国家整体中不同民族、不同宗教、多元文化的生态意识在生态理念方面的协调性。 相似文献
1000.
To assess P losses to surface water by runoff during the rice season and by drainage flow during the winter wheat season, serial field trials were conducted in different types of paddy soils in the Tai Lake Region (TLR) during 2000 and 2001. Four P application rates were set as 0 (CK), 30, 150, and 300 kg P/hm2 for flooded rice trials and 0 (CK), 20, 80, 160 kg P/hm2 for winter wheat trials respectively. Field experiments were done in two locations with a plot size of 30 m2 and four replications in a randomized complete block design. A simplified lysimeter was installed for each plot to collect all the runoff or drainage flow from each event. Total P (TP) losses to surface water during rice season by runoff flow from four treatments were 150 (CK), 220 (T30), 395 (T150), 670 (T300) g P/hm2 in year 2000, and 298, 440, 1828, 3744 g P/hm2 in year 2001 respectively in Wuxi station, here the soil is permeable paddy soil derived from loam clay deposit. While the losses were 102, 140, 210, 270 in year 2000, and 128, 165, 359, 589 g P/hm2 in year 2001 respectively in Changshu station, here the soil is waterlogged paddy soil derived from silt loam deposit. During the winter wheat season, total P lost from the fields by drainage flow in the four treatments were 253 (CK), 382 (T20), 580 (T89), 818 (T160) g P/hm2 in year 2000–2001, and 573.3, 709.4, 1123.2, 1552.4 g P/hm2 in year 2001–2002 at the Wuxi station. While these were 395.6, 539.1, 1356.8, 1972.1 g P/hm2 in year 2000–2001, and 811.5, 1184.6, 3001.2, 5333.1 g P/hm2 in year 2001–2002 at the Changshu station. Results revealed that P fertilizer application rates significantly affected the TP concentrations and TP loads in runoff during the rice season, and by drainage flow during the winter wheat season. Both TP loads were significantly increased as the P application rate increases. The data indicate that TP losses to surface water were much higher during the winter wheat season than during the rice season in two tested sites. The data also reveal that the annual precipitation and evaporation rate affected the soil P losses to surface water significantly. Year 2000 was relatively dried with higher evaporation thus P losses to water by both runoff and drainage flow were less than in year 2001 which was a relatively wet year with lower evaporation. Results indicate that texture, structure of the soil profile, and field construction (with or without ridge and deep drains) affected soil P losses to surface water dramatically. Annual possible TP lost to water at the application rate of 50 kg P/hm2 year tested in TLR were estimated from 97 to 185 tones P from permeable paddy soils and 109–218 tones P from waterlogged paddy soils. There was no significant difference of TP lost between the CK and the T50 treatments in both stations, which indicate that there is no more TP lost in field of normal P fertilizer application rate than in control field of no P fertilized. Much higher TP lost in runoff or drainage flow from those other P application rates treatments than from the T50 treatment, which suggest that P losses to surface water would be greatly increasing in the time when higher available P accumulation in plough layer soil in this region. 相似文献