杉木人工林养分循环随林龄变化的特征

AimsThe purpose of this study is to investigate the characteristics of nutrient cycling in Cunninghamia lanceolata plantations with different ages, and to provide scientific basis for the management of high-yield plantations in China.Methods In this study, we used the ecological data of the past 25 years in Hunan Huitong Ecological Station and analyzed the nutrient cycling characteristics of the C. lanceolata plantation forests with different ages according to the law of tree growth and the dynamics of nutrient uptake.Important findings For most nutrients, their concentrations ranked in order as leaf > twig > bark > root > stem for all C. lanceolata trees with any ages.When the tree age was less than 12 years, nutrient concentrations increased with age, while they decreased with age when the tree was more than 12 years old.The changes in average annual nutrient uptake with age showed two peaks.Nutrient return gradually increases with age.For the same age, the nutrient use efficiency followed the order of phosphorus (P) > potassium (K) > nitrogen (N) > magnesium (Mg) > calcium (Ca).After the stand was closed, the nutrient utilization efficiency increases with the growth and development of trees.The cycling intensity of Ca and Mg was greater than that of N and P at the same stand age.The changes in nutrient cycling intensity with age varying curve with stand age acted as parabolic curve.Utilization of N, P and K was longer than displayed a parabolic shape for all elements.The utilization time of each element got shorter with increasing stand age.These results suggested that the nutrient uptake in different growth stages was not only controlled by the quantity of biomass, but also affected by the difference in nutrient concentration between previous and current stages.The nutrient cycling processes were jointly controlled by the mechanisms of nutrient redistribution and storage in Cunninghamia lanceolata, during the growth and development stages, and the nutrient use efficiency during different growth stages.