青海大通退耕还林工程区林木生产力和水分生产潜力研究

为明确青海大通退耕还林工程建设发展方向，2002年至2003年，通过对青海省大通县20世纪80年代退耕还林后，现存人工林群落标准地调查和解析木分析，研究了青杨灌木混交林、白桦云杉混交林、落叶松纯林、紫果云杉纯林、白桦纯林等5种类型的林木生产力和林木水分生产潜力．结果表明，研究地区的植物气候生产潜力约为8 462 kg/(hm2·a)，2 100～3 333株/hm2密度的青杨灌木混交林、白桦纯林、紫果云杉纯林和白桦云杉混交林的生产力指标可作为该地区常规造林技术条件下乔木成林的现实生物量生产潜力标准．其中，紫果云杉纯林和白桦纯林成林的现实潜在水分生产率分别为17.22和22.14 kg/(hm2·mm·a)，青杨灌木混交林和白桦云杉混交林成林的现实潜在水分生产率分别为21.14和19.09 kg/(hm2·mm·a)．表明上述类型的造林模式是今后退耕还林工程建设的发展方向． 

Tree productivity and water production potential in Returning Farmland to Forest Project in Datong County, Qinghai Province

To make clear the development direction of the Returning Farmland to Forest Project in Datong County, Qinghai Province, from 2002 to 2003，based on the investigation of sample plots and stem analysis of remained plantation communities in the areas of returning farmland to forest in the 1980’s in this region，the authors studied tree productivity and moisture potential productivity of five types of plantations on the land of returning farmland to forest，including Populus cathayana and shrub mixed forest，Betula platyphylla and Picea asperata mixed forest，Larix principis_rupprechtii pure forest，Picea purpurea pure forest and Betula platyphylla pure forest．The results show that：in sub_humid region of Loess Plateau，plant climate potential productivity is about 8 462 kg/(hm²·a)，the productivity index of P. cathayana and shrub mixed forest，B. platyphylla pure forest，P. purpurea pure forest and B. platyphylla and P. asperata mixed forest with the density of 2 100-3 333 per hm² can serve as a potential productivity standard of actual biomass of established arbor forests under the local conditions．The actual potential water productive efficiency of P. purpurea pure forest and B. platyphylla pure forest are 17.22 and 22.14 kg/(hm².mm.a) respectively，and that of P. cathayana and shrub mixed forest and B. platyphylla and P. asperata mixed forest are 21.14 and 19.09 kg/(hm².mm.a)．These types of forestation models are the development direction of the Returning Farmland to Forest Project．