[目的]探讨杉木[Cunninghamia lanceolata ( Lamb.) Hook]林物质生产中养分利用特征,为其人工林经营管理提供科学依据。[方法]本研究在湖南会同杉木林生态系统研究站(国家野外科学观测研究站)进行。供试林分 7 年生时,在林内设立了 4 块固定观测样地,并在林分 7、11、16、20、25 年生 5 个林龄时,测定林分生物量,测定树木中 K、Ca、Mg、N 和 P 含量。根据枝叶枯死前后养分浓度差异和枝叶枯死量,估算枝叶枯死前的养分转移量。用某林龄段首尾两次测定的养分浓度差值,估算某林龄段以前生长且在该林龄段仍存活的生物质中新补充或转移出的养分量。将这些养分与从土壤吸收的养分结合一起,综合分析林分物质生产中的养分利用特征。[结果]林分物质生产利用的总养分中,土壤养分比例占 79.3%~96.5%,随林龄增加持续下降;枝叶枯死前转移的养分占 3.52%~17.6%,随林龄增加持续上升;林分 12 年生后,积累在某林龄段开始前林分生产的,在某林龄段结朿时仍存活的器官物质中迁移出的养分再利用占 3.11%~3.40%,随林龄增加呈下降趋势,但变化幅度不大。树干高生长阶段以前,养分利用效率随林龄增加而下降,进入树干高生长阶段以后,养分利用效率随林龄增加而上升。[结论]林分用于物质生产的养分来自土壤、枝叶枯死前转移和植物活组织转移 3 个方面的养分。只要有枝叶枯死发生,枝叶枯死前就有养分迁移出来用于物质再生产。只有杉木林郁闭后,才发生某林龄段以前林分生产的,且在该林龄段仍存活的生物质中有部分养分被迁移出来再利用。林分养分利用的年变化受不同生长阶段对养分需求量的制约,同时杉木体内养分再分配及贮备机制、杉木生长规律和不同生育阶段对养分的利用效率等共同调控着养分利用过程。
【Objectives】This study was to investigate the nutrient utilization characteristics in the material production of Chinese fir [Cunninghamia lanceolata (Lamb.) Hook] plantations and to provide a scientific basis for the management of Chinese fir plantation.【Methods】The study was conducted at the Ecosystem Research Station for Chinese Fir Plantation (National Outdoor Scientific Research Observation Station) in Huitong County, Hunan Province, China. Four localized observation sampling plots were established in a seven-year-old plantation. In the 7th, 11th, 16th, 20th and 25th year, the stand biomasses were measured, the total Ca, Mg, K, N and P contents in different plant parts were analyzed. The transferred nutrient amounts from the dead branch and leaves were calculated via multiplying their biomass by the nutrient concentration difference values before and after their death. According to the periodical nutrient concentration differences, the supplemented or removed quantities of nutrients from various organs born before this forest age stage were estimated. These nutrients were combined with nutrients absorbed from soil.【Results】With the increasing of forest age, the percentage of nutrient provided by soil, which was in range of 79.3%–96.5%, became decreasing;that by transfer out of branches and leaves before death, which was accounted for 3.52%–17.55%, became rising. Only since the 12th year of stand, there occurred reuse of nutrients transferred out of the biomass born before and still alive in a certain forest age stage. These shifts accounted for 3.11%–3.40% and showed a small amplitude downward trend with the increase of forest age. Before the fast trunk growth stage, nutrient use efficiency declined with the increasing forest age. Since the fast trunk growth stage, nutrient use efficiency rose with the increasing forest age.【Conclusions】The nutrients used for material production in stand come from three aspects: soil, pre-death transfer of branches and leaves and plant tissue transfer.
Journal of Plant Nutrition and Fertilizers
Cunninghamia lanceolata (Lamb.) Hook
internal nutrient cycling