摘要
利用地理信息系统技术结合典范对应分析和数量区划的方法 ,研究了黄土高原地区植被与气候之间的关系。排序结果表明 :CCA的第一轴代表黄土高原植被和气候梯度的纬向性变化 ,水分梯度是决定植被分布的最主要气候因子 ,热量梯度中的全年月平均最低气温、月平均最高气温、年均温也对植被的纬向性分布有较大的影响 ,黄土高原植被与气候梯度表现出明显的纬向性 ;CCA的第二轴代表黄土高原植被和气候梯度的经向性变化 ,热量梯度是决定植被经向性分布的最主要气候因子 ,水分梯度中的全年最大蒸散量对植被的经向性分布有较大的影响。黄土高原植被与气候梯度表现出明显的经向分布规律性。
Many ecological methods are available in micro-scale studies, however, the studies in Loess Plateau use landscape scale. Quantitative ecological method is a group technique of multivariate analyses and becomes more and more important in vegetation studies. Geographical Information System(GIS) can not only store and manage spatial data, but also provide easy ways of spatial analyses, which may meet the demands of ecological researches in landscape scale with a lot of spatial data. A new technique combining GIS and quantitative ecological method is presented in this paper. The relationships between vegetation and climatic variables in Loess Plateau are analyzed by using GIS combining the canonical correspondence analysis(CCA). Loess Plateau ,situated at E100°52′～114°33′,N33°41′～41°16′,is a part of Northwest China. For a long time, severe erosion not only has produced a great impact to agriculture in this area, but also silted up the reservoirs and riverbeds in the lower reaches, so it has been becoming the most important cause seriously damaging the ecological system of the Loess Plateau and the near areas. Loess Plateau is the basis of the GIS to produce electronic pool of vegetation maps of Loess Plateau. Two methods were adopted: Digitization Method and Analytical Method. Loess Plateau is divided into 257 districts by using the net of altitude 30′and longitude 30′in the diagram of Loess Plateau vegetation types. It includes 171 vegetation types. Based on climatic materials in the Loess Plateau, 9 climatic variables are selected. Vegetation data matrix of 257×171 and climatic data matrix of 257×9 are got by using Digitization Method and Analytical Method. Ordination is a group technique of multivariate analyses and becomes more and more important in vegetation studies. Many ordination methods are available in modern ecology, however most of them analyze vegetation composition only. Based on Reciprocal Averaging(RA),this method is named CCA .It combines vegetation data and environment data by the way of multi-regression. CCA is applied to the study of the relationships between vegetation and climate in Loess Plateau. The outcome illustrates that CCA describes the relationships between vegetation and climate clearly and is an effective and time-saved methodology. The ordination results are as follows: the results of ordination indicate that the geographical distribution of vegetation in Loess Plateau is closely related to ecological gradients, i.e. to climate variables. The first CCA axis express the variation of vegetation and climate along latitude in Loess Plateau .It shows the variation of temperature and water-conditions. Moisture is the main factor that decides the latitude distribution of vegetation. In addition, the monthly mean lowest temperature, the monthly mean highest temperature, and annually means temperature also play an important role in latitude distribution. There are obvious trends in longitude for vegetation and climate distribution in Loess Plateau. The second CCA axis express the variation of vegetation and climate along longitude in Loess Plateau . It illustrates the gradient of temperature and water-conditions as well, however the latter more apparent, and it also illustrate the effects of elevation. Temperature is the main factor influencing longitude distribution of vegetation, and the maximum evaporation is also important. The distribution of vegetation and climate variables along longitude is obvious. The vegetation of Loess Plateau is regionized by TWINSPAN (Two-way indicator species analysis). Four vegetation regions and five sub-regions of Loess Plateau are recognized by TWINSPAN. From southeast to northwest, the four vegetation regions are forest region, forest-steppe region, temperature steppe region,desert and semi-desert region. Two sub-regions of forest region are warm temperate deciduous forest sub-regions and temperate deciduous forest sub-region .The temperate steppe region includes three sub-regions: Meadow steppe sub-region, typical steppe sub-region and desert-stepp
出处
《生态学报》
CAS
CSCD
北大核心
2003年第1期82-89,共8页
Acta Ecologica Sinica
基金
国家自然科学基金资助项目 ( 30 0 70 1 4 0 )
关键词
黄土高原地区
地理信息系统
典范对应分析
植被分析
气候因子
Loess Plateau
geographical information system
canonical correspondence analysis
vegetation analysis
climatic factors
