调亏灌溉对冬小麦耗水特性和水分利用效率的影响-researchgate.doc

氮磷添加对华南热带森林尾叶桉木质残体分解和养分动态的影响( 陈 瑶1,2王法明1莫其锋1,2李钦禄3邹 碧1李应文1李晓波1吴靖滔1,2李志安1** 中国科学院华南植物园退化生态系统植被恢复与管理重点实验室广州510650 2中国科学院大学北京100049 3广东茂名市小良水土保持试验推广站 茂名 525029 摘 要 木质残体（Woody debris, WD）是森林生态系统中一个重要的碳库和营养源，在全球变暖、氮沉降日益严重的今天，研究氮磷沉降影响WD分解的反应机制对于应对环境变化具有重要意义。本文以小良热带阔叶林尾叶桉（Eucalyptus urophylla）WD为研究对象，人工模拟氮（N）和磷（P）添加对尾叶桉WD分解速率及养分释放的影响，结果表明：与对照相比，N添加使WD分解速率常数k降低了11%，而P添加显著提高分解速率常数k（p=0.027）上升幅度为6%。这表明，富氮缺磷的热带森林，P的可利用性限制了WD分解速率，P限制有利于WD中碳的固存。N添加、P添加改变了尾叶桉WD分解过程中N元素的迁移模式，与对照相比，两种处理均使N元素迁移方式由直接释放改变为淋溶—富集—释放，而对分解过程中P元素的迁移模式有不同影响，N添加使P元素的迁移方式由直接释放改变为淋溶—富集—释放，P添加使P元素的迁移方式改变为富集—释放。分解过程中质量残留率与分解过程中C/N比，C/P比呈显著负相关。可见，N、P沉降的增加对WD分解速率和养分释放模式有不同的效应。图4表3参4 关键词 热带土壤氮沉降磷 Effects of nitrogen and phosphorus additions on woody debris decomposition in a secondary tropical forest of Southern China* CHEN Yao1, 2, WANG Faming1, MO Qifeng1, 2, LI Qinlu3, ZOU Bi1, LI Yingwen1, LI Xiaobo1, WU Jingtao1, 2 LI Zhi’an1** 1Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China 2University of Chinese Academy of Sciences, Beijing 100049, China 3Xiaoliang Research Station for Water and Soil conservation, Maoming 525029, China Abstract Objectives: Woody debris (WD) is an important structural component of many forest ecosystems and plays a key role in carbon sequestration. Despite the large amounts of carbon stored in WD, fewer ecological studies have focused on the decomposition of WD in tropical forests than that of litter. Understanding the factors controlling organic matter decomposition in tropical forests is critical to mitigate climate change, such as the chronically elevated atmospheric nitrogen and phosphorus deposition. Methods: We conducted a factorial fertilization experiment in a tropical forest in South China to investigate the influence of nitrogen (N) and phosphorus (P) availability on WD decomposition using branch segments (5-cm diameter) of Eucalyptus urophylla in plots fertili