叶的采取位置和采取时间是用叶分析判断林木营养状态的基本问题,作者就这个问题以赤松(Pinus densiflora)、柳杉(Cryptomeria japonica)、赤杨(Alnus inokumae)、白桦(Betula platyphylla)、日本落叶松(Larixleptolepis)等树种为材料,进行了大量的研究,结果指出林木叶内的N、P、K、Ca The location of the leaves and the time taken to take them are the basic questions for the assessment of the nutritional status of the trees by the leaf analysis. The authors used the Pinus densiflora, Cryptomeria japonica, Alnus inokumae, Betula platyphylla, Japan Larix leptolepis and other tree species as a material, conducted a large number of studies, the results pointed out that N, P, K, Ca