中国北方草地植物群落季节生长格局模拟

中国北方草地横跨干旱、半干旱及亚湿润干旱气候区，水分是限制中国北方草地植物群落生产力的主要气候因子.采用基于水分平衡过程的、简单的植物群落模型，利用460个气象站40年气象数据的月平均值，模拟中国北方7种草地类型的季节及年生长、叶片投影盖度(FPC)、蒸发系数(k)及净第一性生产力(NPP).野外观测数据对模型的验证显示模拟结果与观测值相符较好.温性草地自东向西，青藏高原自东南向西北，植物群落的k、NPP与FPC呈递减趋势，显示了中国温性草地自东向西，青藏高原自东南向西北逐渐干旱的水分梯度；其中高寒草甸的3个模拟参数值均最高，高寒草原FPC次于高寒草甸，而NPP却与温性典型草原相近，温性典型荒漠的3个参数最低.高寒草甸、高寒草原、温性草甸草原、温性典型草原、温性荒漠草原、温性草原化荒漠和温性典型荒漠等7种类型草地的畜群承载力约为每公顷5.2、2.3、3.6、2.1、1.0、0.6和0.2只羊单位，区域最适恢复植被盖度分别以93%、79% 、56%、50%、44%、38%和37%为宜.

Simulation on the seasonal growth patterns of grassland plant communities in northern China.

Soil moisture is the key factor limiting the productivity of grassland in northern China ranging from arid to subhumid arid regions. In this paper, the seasonal and annual growth, foliage projective cover (FPC), evaporative coefficient (k), and net primary productivity (NPP) of 7 types of grasslands in North China were simulated by using a simple model based on well established ecological processes of water balance and climatic data collected at 460 sites over 40 years. The observed NPPs were used to validate the model, and the simulated NPPs were in high agreement with the observed NPPs. The simulated k, NPP, and FPC deceased from east to west in temperate grasslands, and decreased from southeast to northwest in Qinghai-Tibet Plateau, reflecting the moisture gradient in northern China. Alpine meadow had the highest k, NPP, and FPC in the 7 types of grasslands, alpine steppe had the second highest FPC but with a NPP similar to that of temperate steppe, and the three simulated parameters of temperate desert were the smallest. The simulated results suggested that the livestock density should be lower than 5.2, 2.3, 3.6, 2.1, 1.0, 0.6, and 0.2 sheep unit·hm^-2, while the coverage of rehabilitated vegetation should be about 93%, 79%, 56%, 50%, 44%, 38%, and 37% in alpine meadow, alpine steppe, temperate meadow steppe, temperate steppe, temperate desert steppe, temperate steppe desert, and temperate desert, respectively.