川西冷杉林下地表苔藓固氮速率及林窗的影响  

Nitrogen fixation rates of ground-dwelling mosses and the influence of forest gaps in fir forest in western Sichuan

作　　者：李晓明[1,2] 李娜[1] 张伏 刘鑫[1] LI Xiaoming;LI Na;ZHANG Fu;LIU Xin(CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization/Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province/Chengdu Institute of Biology,Chinese Academy of Sciences,Chengdu 610213,Sichuan,China;Maoxian Mountain Ecosystem Research Station,Chengdu Institute of Biology,Chinese Academy of Sciences,Maoxian 623200,Sichuan,China;Dagu Glacier Scenic Area Administration Bureau,Heishui 623500,Sichuan,China)

机构地区：[1]中国科学院山地生态恢复与生物资源利用重点实验室/生态恢复与生物多样性保育四川省重点实验室/中国科学院成都生物研究所,四川成都610213 [2]中国科学院茂县山地生态系统定位研究站,四川茂县623200 [3]阿坝州达古冰川风景名胜区管理局,四川黑水623500

出　　处：《草业科学》2024年第8期1857-1864,共8页Pratacultural Science

基　　金：国家生态科学数据中心开放基金项目(NESDC20210102);四川省自然科学基金项目(2023NSFSC0198)。

摘　　要：苔藓与蓝细菌的共生固氮作用为许多生态系统贡献了高达50%氮输入,是“新增”氮素的重要来源。然而,苔藓与蓝细菌共生固氮速率如何受林窗等生态系统动态影响仍然未知。本文研究了四川西部典型藓类冷杉林地表苔藓与蓝细菌的固氮速率在生长季内的动态变化,及其在林窗和林冠覆盖两种生境下的差异,并评估了苔藓含水量、气温和光照条件等因素对固氮速率的驱动作用。研究结果发现,锦丝藓(Actinothuidium hookeri)和塔藓(Hylocomium splendens)生长季平均固氮速率分别为77.49和129.69 nmol·(g·d)^(−1)。地表苔藓固氮速率在生长季不同月份的变化极大,固氮速率高峰出现在生长季早期的5月、7月、8月,基本与植物生长高峰期相符;6月苔藓含水量较低,导致苔藓几乎没有固氮活性;生长季末期的10月苔藓固氮速率较低,不及7月的1/7。相比于林冠覆盖生境,林窗提高了地表气温、光照和苔藓含水量,但从整个生长季来看,林窗对苔藓固氮速率仅表现出微弱的促进作用。综上,苔藓与蓝细菌共生体固氮速率和林窗的影响效应可以为深入认识生态系统氮循环提供依据。Symbiotic nitrogen fixation by moss-cyanobacteria associations is a critical process that contributes up to 50%of the nitrogen input in many ecosystems.However,how the nitrogen fixation rate of the moss-cyanobacteria association is affected by ecosystem dynamics remains unknown.This lack of clarity is a substantial impediment to effectively modeling ecosystem N budgets.Here,we investigated dynamic changes in the nitrogen fixation rates of understory mosses in a typical fir forest in the eastern Tibetan Plateau during the growing season and the influence of forest gaps on this process.The results showed that Actinothuidium hookeri and Hylocomium splendens exhibited average nitrogen fixation rates of 77.49 and 129.69 nmol·(g·d)^(−1),respectively,during the growing season.Nitrogen fixation rates displayed significant seasonal variation,with peaks in May,July,and August,coinciding with peak plant growth periods.Water limitation in June resulted in minimal nitrogen fixation. The rates in October were also lower, reaching only one-seventh of those observed in July. Forest gaps increased the surface temperature, light availability, and water content of mosses. However, forest gaps had only a weak positive effect on the nitrogen fixation rate of mosses. In summary, these results provide a basis for understanding nitrogen cycling in ecosystems.

关 键 词：冷杉林 生物固氮 氮循环 林窗 苔藓 原始林 乙炔还原法 

分 类 号：S718.5[农业科学—林学]