典型气候条件下东北地区生态系统水源涵养功能特征

东北地区是我国重要的生态功能区,其包含的典型生态系统具有独特的水源涵养功能,在防洪减灾,保障生态安全和人居安全中发挥着关键作用。以往有关水源涵养功能的研究主要是依托不同水文模型方法,从单一年份或多个年份的角度进行研究,较少考虑不同气候条件下水源涵养功能的空间分异特征。采用标准化降水蒸散发指数(Standardized Precipitation Evapotranspiration Index,SPEI)划分研究区的典型气候年份(干旱、正常和湿润);基于水量平衡法,结合SCS-CN模型以及Penman-Monteith方程对东北地区典型气候条件下生长季内的水源涵养功能进行研究。结果表明:(1)研究区水源涵养功能在不同气候条件下差异明显,三个典型气候年份生长季内的水源涵养总量分别为:干旱年(SPEI=-1.26)为2214.64亿m~3、正常年(SPEI=-0.22)为3231.49亿m~3和湿润年(SPEI=1.05)为3969.33亿m~3。(2)水源涵养功能空间变异突出,但在三种典型气候条件下呈现出一致变化,均表现为长白山地区水源涵养量最大,大小兴安岭地区次之,水源涵养量最低的地方主要出现在呼伦贝尔以西的草原地区,在东北平原的部分地区也有低值的出现,如白城、通辽、鸡西等地区,水源涵养量较一般的地方出现在东北平原大部分以农田为主的地区。(3)水源涵养功能除受气候因素的影响外,还取决于土地利用类型的变化,对于整个东北地区来讲,水源涵养总量表现为林地农田草地湿地,单位面积水源涵养量在干旱年和正常年表现为林地农田湿地草地,在湿润年份表现为林地湿地农田草地。研究结果揭示了东北地区三种典型气候条件下重要生态系统的水源涵养功能大小、空间分布特征及其主要驱动因素,可为区域生态空间规划和生态系统管理提供科学指导。

Spatial analysis of water conservation function in northeast China under different climatic conditions

Northeast China is one of the important ecological functional areas in China. There are several types of ecosystems in the region and each has its unique water conservation function. Ecosystems are known to play a significant role in flood control and disaster reduction, as well as provide ecological and human settlement security. Previous studies on water conservation function have depended mainly on different hydrological models with varying temporal scales; however, few studies have investigated the spatial distribution of water conservation function under different climatic conditions. In the present study, a standardized precipitation evaporation index (SPEI) was used to select the typical climate years (dry, normal, and wet) for the study area. The water conservation function under different climatic conditions was analyzed based on the water balance method, the SCS-CN model, and the Penman-Monteith equation. The results indicated that the total amount of water conservation in the growing seasons varied significantly under different climatic conditions in northeast China. They were 221.464, 323.149, and 396.933 billion m³ in the dry (SPEI=-1.26), normal (SPEI=-0.22), and wet year (SPEI=1.05), respectively. The Changbai mountain area had the highest water conservation function, followed by the Daxing''an and Xiaoxing''an Mountain areas. The lowest water conservation quantity was distributed mainly in the pasture area in the west of Hulunbuir. Some areas of the Northeast Plain also had low water conservation such as Baicheng, Tongliao, and Jixi. Moreover, the areas of farmland plain, located in the middle, south, and east of northeast China such as most areas of Songnen, Liaohe, and Sanjiang plains had moderate water conservation function. Both climatic conditions and land-use types affected the extent of water conservation. The total amount of water conservation followed the order of forest > cropland > grassland > wetland. In dry and normal years, land use dramatically affected the average water conservation capacity per area in the order of forest > cropland > wetland > grassland. In contrast, the order of the value for wet years is forest > wetland > farmland > grassland. These results reveal the quantity, spatial distribution, and main driving factors for water conservation in important ecosystems under three typical climates in the northeast of China. This provides scientific guidance for regional ecological space planning and ecosystem management.