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杨树细根碳、氮含量的季节动态及代际差异

王延平1,2,许坛3,朱婉芮1,王华田1,2**,张光灿1,2,李传荣2,姜岳忠4   

  1. (1山东农业大学林学院, 山东泰安 271018;  2国家林业局泰山森林生态系统定位研究站,  山东泰安 271018; 3北京林业大学林学院, 北京 100083; 4山东省林业科学研究院, 济南 250014)
  • 出版日期:2015-11-18 发布日期:2015-11-18

Seasonal dynamics of carbon and nitrogen in fine roots and their differences between successive rotation poplar plantations.

WANG Yan-ping1,2, XU Tan3, ZHU Wan-rui1, WANG Hua-tian1,2, ZHANG Guang-can1,2, LI Chuan-rong2, JIANG Yue-zhong4   

  1. (1College of Forestry, Shandong Agricultural University, Tai’an 271018, Shandong, China; 2Taishan Forest Ecosystem Research Station, State Forestry Administration, Tai’an 271018, Shandong, China; 3College of Forestry, Beijing Forestry University, Beijing 100083, China; 4Shandong Academy of Forestry, Ji’nan 250014, China)
  • Online:2015-11-18 Published:2015-11-18

摘要: 研究杨树人工林1~5级根序细根内碳、氮及非结构性碳水化合物含量的季节动态,对比了杨树细根碳氮分配格局的代际差异,以期建立细根生长和功能变化与连作人工林生产力衰退的联系.结果表明: 杨树细根非结构性碳水化合物(NSC)随根序显著增加,而氮含量显著减少.细根中全C和NSC含量与全N存在显著相关性.细根碳氮含量的变化在根序间的解释量占98.2%,而在代际间仅为1.7%.杨树不同根序细根均在生长季具有较高的碳含量和较低的氮含量,且碳、氮及NSC含量在代际间随季节差异显著,但C∶N差异不显著,根序与季节对细根碳氮含量存在显著交互效应.杨树低级细根C∶N约为20∶1,高级根则大于30∶1.细根C∶N在生长季(7和9月)显著低于其他季节,NSC含量在11月最高.连作人工林杨树细根的碳氮分配格局与细根根序具有较强的耦合性,NSC和C∶N在指示细根周转和调控细根季节性生长中具有重要生态学意义.

Abstract:

In this study, poplar fine roots in two successive rotation plantations were sampled over seasons. Root samples were grouped from first to five orders to examine the seasonal dynamics of carbon and nitrogen contents of poplar fine roots with orders, and compared their differences between two successive rotation plantations, and finally to find the relationships between the fine root growth and the productivity decline of successive rotation poplar plantations. The results showed that nonstructure carbohydrates (NSC) content increased significantly with root orders, while nitrogen content decreased. The contents of total carbon and NSC were significantly related to total nitrogen content. Root orders explained 98.2% variance of carbon and nitrogen contents of poplar fine roots, and the difference between rotations only explained 1.7% of variance. Poplar fine roots consisted of more carbon and less nitrogen with root orders, and the seasonal changes in contents of total carbon, total nitrogen and NSC showed significant difference between rotations, while that of the C:N ratio didn’t show significant difference. Root order and season showed interaction effect on carbon and nitrogen dynamic. The C:N ratio was about 20:1 in lower order roots,  and more than 30:1 in higher order roots. The C:N ratio in summer and autumn was significantly less than those in other seasons, while NSC content was the highest in November. This study indicated that the allocation of carbon and nitrogen in fine roots was closely correlated with fine root orders. Both NSC content and C:N ratio were of greatly important ecological significance in fine root turnover and growth regulation.