氮磷配施促进杉木生长和材质稳定性:来自长期施肥试验的启示OA

[Objective]This study aims to investigate the effects of different fertilization treatments on the growth and wood quality parameters of Chinese fir(Cunninghamia lanceolata),thereby providing a theoretical basis for cultivating high-quality large-diameter timber and achieving sustainable forest management.[Method]Based on a long-term fertilization experimental platform for Chinese fir plantations,four treatments were set up:control,nitrogen application alone(100 kg·hm-2 a-1),phosphorus application alone(50 kg·hm-2 a-1),and combined application of nitrogen and phosphorus(100 kg·hm-2 a-1 N+50 kg·hm-2 a-1 P).The fertilization experiment was initiated in 2012,with fertilizers applied four times annually(in March,June,September,and December,at proportions of 30%,30%,20%,and 20%,respectively).Nitrogen and phosphorus fertilizers were applied in the forms of ammonium nitrate and sodium dihydrogen phosphate,respectively,mixed uniformly with river sand.Tree-ring analysis was employed to measure annual ring width and latewood rate for each year from 2011 to 2023.The responses of growth and wood property indicators to long-term fertilization were analyzed based on the inter-annual coefficient of variation(CV)of ring width and latewood rate,along with fertilization effect values.The piecewise linear regression and mixed-effects models were used to identify the impacts of fertilization duration and tree diameter class on these indicators.[Result]1)Compared to single-nutrient applications,the combined application of the N+P dampened the interannual fluctuations in ring width and latewood rate caused by extreme drought,buffering tree growth sensitivity and yielding wood uniformity comparable to the control.2)Under the N+P treatment,the cumulative promoting effect on growth peaked after four consecutive years of fertilization,resulting in a 31.8%increase in cumulative ring width compared to the control.Concurrently,the decrease in cumulative latewood rate was more moderate than that under the P-alone treatment and remained similar to the control levels.3)The N+P combination alleviated competition among trees of different diameter classes,promoted overall stand growth,and effectively suppressed the diameter class differentiation phenomenon induced by single-nutrient fertilization.[Conclusion]It is recommended to implement a combined nitrogen and phosphorus application regimen on a four-year cycle in mid-aged C.lanceolata stands.This approach aims to enhance growth rates while ensuring uniformity in wood texture and maintaining hardness.