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选取不同类型退化湿地的典型退化指标,如湿地面积变化率、水源补给状况、地表水水质、濒危物种数和种群数量变化率、植被覆盖变化率等作为湿地退化状况的评价指标,将湿地的退化程度划分为4个等级:未退化、轻度退化、重度退化和极度退化,并对10处滨海国际重要湿地和22处内陆国际重要湿地的退化状况进行了评价。评价结果表明,2个湿地是严重退化,1个湿地是轻度退化,其余29个湿地是未退化。 相似文献
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山丹县防护林建设对县域发展做出了积极贡献,但受多种因素影响,近年来防护林出现大面积退化。以山丹县2022年森林资源和国土资源调查结果为依据,对县域内退化防护林进行全面调查,统计退化面积、林种类型、退化程度、分布特征等。结果表明:全县退化防护林面积达到4 384.77 hm2,其中农田牧场防护林占80.59%,防风固沙林占19.41%;轻度退化8.28%,中度退化63.55%,重度退化28.17%;重度退化林地土壤有机质含量和养分指标含量显著低于中度和轻度退化林地(P<0.05),极显著低于未退化林地(P<0.01)。综合来看,山丹县退化防护林以中度退化为主,多为农田牧场灌木防护林,且退化程度越高,土壤状况越差,应结合调查结果及时开展精准修复。 相似文献
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渭南市秦岭北麓退化防护林在一定程度上影响着区域整体生态防护功能的发挥。按照《陕西省三北工程退化林草调查技术方案》规定的调查方法,对渭南市秦岭北麓临渭区、华州区、华阴市、潼关县退化防护林进行调查分析,秦岭北麓退化防护林总面积21 354.74 hm2,从面积结构上看,华州区>华阴市>临渭区>潼关县;从退化林起源看,天然林面积大于人工林面积;从退化原因面积分布上看,生理>立地>人为>灾害;从退化程度面积分布上看,中度>轻度>重度。退化类型主要有4种,提出更替修复、抚育修复、择伐补植修复、渐进修复、封育修复等5类9种修复措施,在制定小班修复技术措施时,应结合具体情况科学选择应用。 相似文献
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桉树连栽人工林地的地表枯枝落叶层中,干物质和各种养分贮藏量与次生阔叶林和厚荚相思林比较明显下降,土壤有机质,全N量和碱解N含量随土壤剖面深度增加也出现下降趋势.传统的砍、烧、机耕整地使桉树林地的枯枝落叶和养分库呈突变形式退化.林分组成单一,凋落物数量和养分含量少,也是桉树林地土壤有机物的养分库退化的原因.通过改变林分组成和施肥,可以控制人工桉树林地有机物和养分库的退化,提高人工林地的生产力. 相似文献
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中国荒漠化评价指标体系 总被引:9,自引:0,他引:9
根据《联合国防治荒漠化公约》对于荒漠化所作的定义 ,该文首先介绍了中国荒漠化现状 ;其次介绍了中国荒漠化评价指标体系 ,其中包括 :(1)荒漠化气候区划 ;(2 )中国土地利用类型划分 ;(3)中国荒漠化成因类型 ;(4)荒漠化程度分级指标 ,其中包括风蚀、水蚀、土壤次生盐渍化以及草原退化 ;最后 ,从理论及经济可行性观点出发 ,详细讨论并列出了可用于荒漠化评价的相关指标 相似文献
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Classification System for Desertification and Its Quantitative Assessment Methodology in China 总被引:1,自引:0,他引:1
WangJunhou ZhangZhiqiang JiaBaoquan MengFanrong 《中国林学(英文版)》2003,5(3):42-48
Based on the desertification definition of United Nations Convention to Combat Desertification and features of desertification in China, three-level hierarchical classification system for desertification and quantitative assessment methodology of desertification degree were developed and used to evaluate desertification danger degree across the country. The system is composed of three components: type of desettification, type of land utilization and degree of desertification. The type of dertification monitored in China was divided into 4 major categories, 15 sub-categories and 52 types. Vegetation coverage, soil characteristics,and topography are considered as three major indicators for quantitative assessment of desertified land. A simple, yet practically sound mathematical assessment model was built using these indicators. Furthurmore, a regional land desertification warning model was also constructed on the basis of the ratios of non-desertified land area to desertified land area in different degrees. The warning result of wind-erosion desertification at county scale for 12 provinces in northern China was also calculated by this model. 相似文献
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论内蒙古四子王旗农牧交错带林地的发展与演化 总被引:1,自引:1,他引:0
内蒙古四子王旗农牧交错带林地属于干旱、半干旱区的林地,在保护国土、改各生态环境、维护生态平衔、拓宽人类活动空间、优化生存环境质量等方面起到了重要作用;尤其是在生态失衡、环境遭到破坏的荒漠化发生地区,以某种特殊目的营建的农防林、水土保持林、水源涵养林等既是农牧业的人工防护屏障,又是整个农业生态系统的骨架。本文就由于过度放牧、樵采和垦荒等破坏植被后导致的沙化,使林地成为沙源地的演化情况进行探讨。 相似文献
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ZHANGFengchun LUQi 《中国林业科技(英文版)》2004,3(4):1-11
Ecosystem degradation occurs in parallel with desertification process in sandy areas of North China. The vast sandy areas in North China are characterized with flexible environments and fragile ecosystems as well as intensive human activities. Due to the annual precipitation gradient decreases from east to west in North China, the whole sandy region falls into 3 main climatic zones: arid, semi-arid and dry sub-humid zones.The ecosystems in each type of climatic zones are different in climatic conditions, human activities, cultural dimensions, vegetation covers, landscapes, and causes and processes of ecosystem degradation. Therefore, the most effective rehabilitation measures of degraded ecosystems in different types of the climatic zones are also different. For the arid sandy areas, vegetation rehabilitation of degraded ecosystems needs to be completely closed, assisting with artificial measures, such as plantation, irrigation or others. For semi-arid sandy areas, the effective measures of vegetation re 相似文献
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LU Qi YANG Youlin WANG Sen WU Bo REN Guoyu JU HongboNational Research Development Center for Combating DesertificationChinese Academy of Forestry. Beijing . ChinaAsia Regional Coordinating Unit. Secretariat of the UNCCD. Bangkok . Thailand Pacific Forestry Center. Canadian Forest Service. Natural Resources Canada West Burnside Road. Victoria. BC. Canada VZ M National Climate Center of China Meteorological Administration. Beiiine . China 《中国林业科技(英文版)》2003,(4)
Serious land degradation exists in the marginal areas of North China, the important ecological transition between semi-arid and sub-humid climate zones, which is a relatively narrow belt with 100-250 km in width and about 2 000 km in length. The annual rainfall varies between 300-400 mm. In the past hundred years (before 2000), most of the land in the region had been used for grazing and dryland cropping. As land-use is intensifying, particularly since 1970s and 1980s, desertification has accelerated. Our case studies in 2000 indicated that: (1) Sand-dust storms are the result of a combination of climate change, such as strong winds and dry weather, but their frequency and intensity are mainly related to precipitation variations. The El Nina/El Nino effect is strongly implicated. (2) Human economic activities result in sufficient sand-dust sources to create a hazard. Large-scale land conversion for cropping, deforestation, irrational use of water resources and over-exploitation of groundwater have all c 相似文献
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黄土区人工与天然植被对凋落物量和土壤有机碳变化的影响 总被引:10,自引:1,他引:9
在黄土丘陵区选择从耕地、草地、灌木林到乔木林样地,不同样地内设立1 m × 1 m(乔木10 m×10 m)的样方,分析样方内凋落物积累量、碳氮含量、土壤有机碳(SOC)和可溶性碳(DOC)含量变化.结果表明:天然草地、灌木林、乔木林凋落物积累量依次为5.3,12.1和32.4 t·hm-2;但人工灌木林和乔木林的凋落物积累量分别为6.7和11.4 t·hm-2,分别是天然灌木林和乔木林的1/2和1/3.随着植被的恢复,天然植被凋落物的C/N高于人工植被(刺槐林除外).与耕地SOC(4.67 g·kg-1)相比,天然灌木林地SOC提高5.9倍,人工灌木林地提高1.8倍;天然乔木林地提高8.0倍,而人工乔木林地仅提高4.0倍.凋落物积累量与0~20 cm土层土壤有机碳存在显著线性相关关系(R2>0.83),但20 cm以下线性相关关系不显著.凋落物积累量与0~10 cm土壤可溶性碳含量存在显著线性相关关系(R2>0.893),与10~60 cm土层线性相关关系不显著,与80~100 cm土壤可溶性碳存在显著线性负相关关系. 相似文献
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我国干旱半干旱地区干旱少雨,地表植被稀疏。然而,具有广泛生态适应性的微生物仍可通过生理代谢活动改变沙土的理化性质,促进土壤形成及植物营养转化,有利于植物生长,在区域荒漠化防治过程中起到重要作用,具有重要的生态学研究意义。文中总结我国干旱半干旱区土壤微生物的空间及季节分布特征,并对影响其分布特征的自然和人为因素进行全面梳理。了解土壤微生物的分布特征及其影响因素,可为土壤微生物在该区域生态恢复方面的应用提供参考。同时,根据区域生态恢复重建及增强区域生态安全保障的需要,对未来研究进行展望。 相似文献
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根据荒漠化的定义以及荒漠化的特点,荒漠化监测与评价指标体系由4个部分组成,即压力指标、状态指标、影响指标和防治指标。压力指标描述的是对自然资源的状态带来影响并导致荒漠化发生的自然和人为驱动因素,用来对荒漠化发展趋势进行评估并进行荒漠化早期预警;状态指标描述的是土地生态系统的状态和特性,可以分为物理指标、化学指标和生物指标,它们分别描述土地生态系统的物理、化学和生物特性;影响指标用来评价荒漠化对人类及其环境带来的影响;防治指标用来评价防治荒漠化采取的行动和措施以及采取这些行动和措施带来的社会经济和自然条件的改善。 相似文献