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以黑龙江省帽儿山林场15年生长白落叶松人工林为研究对象,通过对针叶进行原位及离体测量获取其原位最大净光合速率(SP_(n max))及离体最大净光合速率(AP_(n max)),分析AP_(n max)随离体时间(t_a)的变化规律,建立SP_(n max)与AP_(n max)和t_a的函数关系,并分析了林木大小及环境因子对AP_(n max)下降过程的影响,构建了长白落叶松SP_(n max)预估模型.结果表明:在不恢复水分供应的条件下,针叶AP_(n max)随t_a的增加而降低,且水汽压亏缺(VPD)和叶片温度(T_(leaf))越高,AP_(n max)的下降速度越快、幅度越大.以VPD和t_a为自变量的线性预估模型对SP_(n max)的拟合效果最好(Ra~2为0.774,RMSE为20.73),模型的预估精度随着t_a的增加而降低,t_a超过20min后,模型预估精度稳定在97%左右.本文采用离体测量方法通过建立回归模型估计长白落叶松的SP_(n max),不仅具有较好的预估能力和相对稳定的估计精度,同时大大提高了SP_(n max)的测定效率,具有较高的应用价值.
The Larix olgensis plantation grown at Maoershan Forest Farm in Heilongjiang Province was used as the research object. The maximum net photosynthetic rate (SP_ (n max)) and maximum net photosynthesis (N max) and AP_ (n max) were calculated. The variation of AP_ (n max) with time t_a was analyzed to establish the functional relationship between SP_ (n max) and AP_ (n max) and t_a. (N max) on the decline of AP_ (n max) were studied.The results showed that AP_ (n max) increased with the increase of t_a without restoration of water supply And decreased with the increase of vapor pressure deficit (VPD) and leaf temperature (T leaf), the faster the decline of AP nmax, the greater the amplitude.The VPD and t_a as independent variables linear prediction model The fitting precision of SP_ (n max) is the best (Ra ~ 2 = 0.774, RMSE = 20.73). The prediction accuracy of the model decreases with the increase of t_a. After t_a exceeds 20 min, the prediction accuracy of the model is stable at 97% In this paper, the SP_ (n max) of Larix olgensis was estimated by using the in vitro measurement method, which not only had a good predictive ability and a relatively stable estimation accuracy, Greatly improve the measurement efficiency SP_ (n max), and has a high application value.