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61.
SUN AiZhi MAYuZhen FENG ZhaoDong LI Fei WU HuiNing 《科学通报(英文版)》2007,52(8):1080-1088
A pollen record from Haiyuan section in the southern part of Ningxia revealed a detailed history of vegetation variation and associated climate changes during the period from~13.0 to~7.0 14 C ka BP.A steppe landscape under a moderately dry(and probably cool)condition(~12.7-~12.1 14 C ka BP)was replaced by a coniferous forest dominating the landscape under a generally wet climate from~12.1 to ~11.01 4C ka BP.This generally wet period,corresponding to the European B?lling/All?rod period,can be divided into three stages:a cool and wet stage between~12.1 and~11.4 14 C ka BP,a mild and rela- tively dry stage between~11.4 and~11.2 14 C ka BP,and a mild and wet stage between~11.2 and~11.0 14 C ka BP.The coniferous forest-dominated landscape was then deteriorated into steppe landscape (~11.0-~10.6 14 C ka BP)and further into a desert steppe landscape from~10.6 to~9.8 14 C ka BP,being correspondent to the European Younger Dryas period.After a brief episode of a cool and wet climate (~9.8-~9.6 14 C ka BP),a relatively mild and dry condition prevailed during the early Holocene(~9.6- ~7.6 14 C ka BP)and then a warm and humid climate started the mid-Holocene(~7.6-~7.2 14 C ka BP). 相似文献
62.
WU Hua TAO Heping LU Yuan 《武汉大学学报:自然科学英文版》2007,12(4):715-720
The eco-environmental frangibility is studied by choosing the factors of land use class change and vegetation cover rate, and the equation of eco-environmental frangibility and its evaluation system are established based on remote sensing (RS) and geographic information system technology (GIS). Four different years of TM images are selected to calculate land use change grads and vegetation cover rate, and the relationship between the two factors and eco-environment frangibility index are build, taking Fuzhou as an example. The character of times change and space distribution of eco-environment frangibility are described. The result indicates the area of eco-environment frangibility increased 2.6% in Fuzhou during twelve years, and expands from the region between infield and forest land to forest land in space distribution. 相似文献
63.
黄大明柳小妮 宋百敏陈俊 Masae Shiyomi 王昱生 Shigeo Takahashi Yoshimichi Hori Yasuo Yamamura 《清华大学学报》2007,12(4):413-423
The vegetation spatial heterogeneity and ecological characteristics in different soil regions were analyzed by surveying the vegetation in 12 different soil regions of Inner Mongolia, China, including conifer- ous-broadleaf deciduous forests, shrub, grassland, and desert regions with 1122 large 2 cm × 2 cm quad- rats (actual size 30 km × 30 km, referred to as L-quadrat hereafter) in about 1.18 million km2. Each L- quadrat was divided into four small 1 cm × 1 cm quadrats (actual size 15 km × 15 km, S-quadrat). The vegetation was analyzed based on the beta-binomial distribution to describe the frequency of occurrence and spatial heterogeneity for each kind of vegetation. The weighted average of the heterogeneity of all vegeta- tion in the same soil region provides a measure of the soil regional landscape level heterogeneity which de- scribes the spatial complexity of the regional landscape composition of the existing vegetation. Comparison of the vegetation characteristics in the 12 soil regions shows that, the calcic gray soil has the highest average vegetation type per quadrat. The largest soil region is calcic chestnut soil and has the most vegetation types. Every soil region has its own dominant vegetation sequence which dominates in occurrence and dominant vegetation types which dominates in spatial heterogeneity. For the Inner Mongolian vegetation, the weighted average of the heterogeneity is 0.60 and the vegetation diversity index is 4.47. 相似文献
64.
西部植被建设对我国整体生态环境的作用 总被引:1,自引:0,他引:1
我国整体生态环境的主要河流长江、黄河都起源于西部,近年来,由于生态恶化造成的沙尘风暴及洪涝灾害不断给全国造成影响和威胁,因此,西部的植被建设必然是关系全国整体生态环境的大事. 相似文献
65.
本文通过宏观区域及人文背景分析,在尊重历史和现实的基础上,针对吐鲁番市文化西路棚户区改造规划这一特定项目,探索在民族地区、市场经济条件下,协调居住者、开发商、政府三方利益诉求,达成问题合理解决的途径。 相似文献
66.
LUO YunLi SUN XiangJun 《科学通报(英文版)》2007,52(15):2115-2122
Based on deep-sea pollen results (512-76 m) from ODP Site 1143 in the southern South China Sea (SCS),the climate and vegetation evolution sequence on the surrounding islands and the exposed continental shelf are discussed. The pollen records show that the pollen influx was quite low before 8.15 Ma and increased dramatically afterwards. The influx changes can be ascribed,on one side,to tectonics deformations around the southern SCS resulting in rapid uplift of islands and subsequent increase of the sediment rates and pollen influx and on the other side to climate cooling and monsoon enhancement. Around 2.63 Ma was another obvious boundary,the increasing of pollen and spores influx since this time was mainly related to global climate cooling. Spectrum analysis of pollen influx values shows that 2 Ma,0.67 Ma,and 0.19-0.17 Ma cycles existed during 12-3.0 Ma,while 0.1 Ma and 46.9 ka cycles existed during 3.0-2.0 Ma. 相似文献
67.
简要介绍了娄烦县的自然生态环境、分布区类型、生活型组成及主要群落类型,提出了植被生态保护利用对策。 相似文献
68.
水库库区桉树轮伐对水土流失的影响研究——以广州水库库区为例 总被引:3,自引:0,他引:3
以广州市白洞水库和吊钟水库作为实验样区,研究分析水库库区桉树轮伐对水土流失的影响.研究基于遥感数据对库区桉树轮伐区的植被覆盖度、土壤侵蚀模数以及水土保持作用系数进行反演和统计分析.结果显示:库区桉树林的轮伐行为将导致植被覆盖度从0.8~0.9下降到0.2~0.3;土壤侵蚀模数从2 000~3 000 t/km2上升到8 000~13 000 t/km2,水土保持作用系数从0.7~0.8下降到0.3~0.5;扰动期长达11个月;产生较严重的水土流失影响. 相似文献
69.
为了研究三峡水库水位消退过程岸滩土壤呼吸及植被化护岸对土壤碳排放影响,以库区澎溪河段岸滩土壤为研究对象,利用Yaxin—1102便携式光合蒸腾仪系统对库区水退过程中岸滩土壤的呼吸速率进行了测定,并同时测定了土壤呼吸测点的土壤温度(土层深度0、5和10 cm)、土壤含水量、土壤有机碳和p H等土壤环境因子。结果表明:水位消退过程中岸滩近水层土壤呼吸速率表现出明显的时间变化,呈单峰曲线,2月份出现峰值;常年非淹水区土壤呼吸速率变动大于近水层,其峰值晚于近水层1个月。研究发现,长时间淹水可降低土壤呼吸强度即有利于岸滩土壤固持CO_2;但退水时间越长,岸滩土壤呼吸强度增加,接近或高于常年非淹没区。研究表明,岸滩现有植被在护岸同时是否亦能保持土壤碳的低水平排放亟待给予深入探讨。 相似文献
70.
重盐碱次生裸地植被恢复技术研究 总被引:2,自引:0,他引:2
研究我国重盐碱裸地如何恢复牧草草原的技术,试验总结了我国以往研究的限于小样方式的技术成果,证明通过大幅度的技术研究可以实现大规模的草原恢复;人工建植(或群落复生)成本也较低,能够获得经济效益。 相似文献