基于IOCS的内蒙古潜在植被NPP空间分布特征研究

以综合顺序分类系统(IOCS)为基础,利用1985-2009年内蒙古及周边常规气象站的观测资料,采用NPP分类指数模型模拟内蒙古各潜在植被类型NPP,分析其空间分布特征及NPP与气候因子之间的关系。研究表明:①内蒙古地区植被NPP在空间分布上表现出一定的经向分布特征,多年均值介于0~366.5 gC·m^-2·a^-1之间,高值区中心分布在大兴安岭东北部;②各潜在植被类型中,碳汇潜力贡献率最大的潜在植被类型为微温微干温带典型草原类(ⅢC),其值为23.6%;最小的为寒温微干山地草原类(ⅡC),接近于0;③内蒙古潜在植被类型NPP表现出明显的干湿地带性和纬度地带性,且随寒温→微温→暖温、微干→微润→湿润→潮湿的变化其NPP值逐渐增大;但暖温极干暖温带荒漠类(ⅣA)和暖温干旱暖温带半荒漠类(ⅣB)并不符合这一规律,主要原因是较高的温度和较少的降水,达不到植被物质生长的需求。

Analysis of Spatial Distribution Features of Potential Vegetation NPP in Inner Mongolia Based on the IOCS

Daily average temperature and precipitation observations during 1985-2009 are collected from 94 meteorological stations in Inner Mongolia and its surrounding areas. On the basis of Integrated Orderly Classification System (IOCS), the net primary productivity (NPP) of potential vegetation types in Inner Mongolia are simulated with the model of classification indices. Then the spatial distribution characteristics and the relationships between NPP and climatic factors are analyzed, and the results are shown as follows: 1) The NPP of Inner Mongolia shows nearly meridional distribution; the mean NPP is from 0 to 366.5 gC·m^-2·a^-1, and the bigger value region is located in the northeast of Greater Hinggan Mountains. 2) The potential vegetation type of the largest NPP is cool temperate perhumid mixed coniferous broad-leaved forest and its value is 231.8 gC·m^-2·a^-1; the second is warm temperate-subhumid forest steppe and its value is 222.8 gC·m^-2·a^-1; besides the minimum is warm temperate-extrarid warm temperate zonal desert, the value of which is only 0.6 gC·m^-2·a^-1. 3) For all the potential vegetation types, the maximum contribution to carbon sequestration potential is cool temperate-semiarid temperate typical steppe, the value of which is 23.6%; the minimum is cold temperate-semiarid montane steppe and the value is close to zero. 4) Each potential vegetation NPP has a higher partial correlation with moisture-humidity than annual cumulative temperature; by the IOCS, which is based on a moisture index, expressed as the ratio between annual precipitation and >0℃ annual cumulative, we can confirm that precipitation is the main factor, which impacts the NPP of potential vegetation types. 5) In Inner Mongolia, the NPP of potential vegetation types show the characteristics of wet-dry and latitude zonality obviously, and the NPP increases gradually as the change is with cold temperate→cool temperate→warm temperate and the diversification is with semiarid→subhumid→humid→perhumid; however, warm temperate-extrarid warm temperate zonal desert and warm temperate-arid warm temperate zonal semidesert do not comply with this law; the main reason is that higher temperature and less precipitation cannot meet the needs of vegetation growth.