Evaluation and diagnosis of tree nutritional status in Chinese-fir (Cunninghamia lanceolata (Lamb) Hook) plantations, Jiangxi, China

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An-Liang Zhong, a, Wen-Yue Hsiungb
a Faculty of Forestry, University of British Columbia, 270–2357 Main Mall, Vancouver, B.C. V6T 1Z4, Canada
b Department of Forestry, Nanjing Forestry University, Nanjing, Jiangsu, 210037, People's Republic of China
Accepted 7 June 1993. Available online 25 June 2003.

Abstract
During the period 1987–1989, 12 plots representing different stand age and site quality were established in the Chinese-fir plantations of Fudong Branch, Fengshushan Forest Station, Jiangxi province. Soil physical and chemical properties, and nutrient (N, P, K, Ca, Mg and S) concentrations in needles and twigs from dominant, average and depressed trees were analyzed in different growing seasons. Principal component analysis (PCA), discriminant analysis (DA), parabola modeling, and diagnosis and recommendation of integrated system (DRIS) were used to evaluate the nutritional quality and nutrient balance of the stands, and to develop nutrient criteria for the soils and trees. Stands CL1, CH1 and TK1 were of high nutritional quality, XW1, CL2 and XW2 showed a moderate nutritional condition, and CH2 and TK2 were poor in nutrition. The discriminant functions YI = −10.94+22.97 XN and YII = − 6.42+17.59 XN (XN is the N concentration in needles) were developed with correctedness of 80% for judging tree nutritional quality. Gravel (> 2 mm) content, pH, total N, hydrolyzable N and extractable P were the main factors affecting tree nutrition and growth. Tree N nutrition closely interacted with P nutrition in the stands. Optimum soil total N, hydrolyzable N and extractable P were 540, 65 and 8 ppm, respectively for 5-year-old stands, 650, 83 and 5 ppm for 10-year-old stands, and 560, 88 and 4 ppm for 20-year-old stands. A uni-variable quadratic model (Y = a + bX + cX2) was most suitable for determining the criteria of N and P concentrations in needles; basically good for K and S criteria establishment, and not fit for that of Ca and Mg. Log ((DBH)2 × height) was the most appropriate growth index for developing such diagnostic equations. Criteria of nutrient concentrations varied between different growing seasons and stand age. Critical nutrient concentrations of N and P during the first fast-growing season, a sensitive period for nutrient deficiency, were 2.19% and 0.13%, 0.83% and 0.13%, and 0.76% and 0.13% for 5-, 10- and 20-year-old stands, respectively. The nutrient indices of N, P and K derived from DAIS demonstrated that most stands needed more K and P than N during the early growing season, N was a key nutrient and most needed, then P in the fast-growing seasons. Optimum ratios of N:P, P:K and K:N were 7.68, 0.12 and 1.09, respectively, for the Chinese-fir stands.


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Copyright © 1993 Published by Elsevier B.V.