施肥对柚木人工林细根周转的影响机制

Plants uptake water and nutrients through fine roots whose turnovers is an important indicator of tree growth and fertility of the soil. Fertilization is a vital operation in plantation management, especially for precious species like teak. Fertilization can improve growth of trees significantly, but its effects on fine root turnovers in plantation have great uncertainties of dimensions and directions, and its function mechanism on FRT is still debatable..Multiple fertilizers and different fertilizing methods will be utilized to examine the effects of fertilization on FRT. According to the measurements of the distribution of FR, FR production and mortality, the spatial and temporal patterns of FR will be illustrated. FR morphology was used to reveal that how fertilization change FR growth. Elementary composition, root vigor, physiological-biochemical characteristics and metabolism of FR were analyzed to explore how fertilization affect FR aging. This study exploiting multiple FR research methodologies can accurately evaluate FRT, deepen the understanding of external induction mechanism of FRT, and uncover the effects of fertilization on FRT. .This study has practical significances to guide scientific fertilizing to promote the healthy stand growth, and to push forward the development of teak plantation in China. This study can also provide a theoretical guide to the maintenance and regulation of site fertility.

细根是植物获取水分和养分的主要途径，其周转速率是指示林木生长状况和林地肥力的重要指标。施肥作为人工林特别是珍贵树种人工林培育的重要管理措施之一，能显著促进林木生长，但对细根周转的影响在程度与方向上差异巨大，作用机制尚不明确。.本研究设置不同施肥方式和肥料种类，通过观测根系分布、细根产生与死亡动态，摸清柚木细根的时空变异性规律；通过观测细根形态，揭示施肥对细根生长的影响效应；采用细根元素组成、细根活性、生理生化和代谢水平等多指标，探求施肥对细根衰老、死亡的影响机理；本研究采用多种细根研究法精确评估细根周转，丰富细根周转的外部诱导机理，揭示施肥对细根周转的影响机理。.本研究对指导科学施肥，促进林分健康发育和提高林分生产力，推动柚木人工林在我国进一步发展，均具重要的现实意义。本研究还将为人工林地力维持与调控提供理论指导。

柚木是世界著名的珍贵树种之一。施肥是柚木人工林高效培育中的常规手段，对柚木生长的促进作用明显，有助于及时郁闭，形成良好干型。但施肥特别是含不同元素的肥料品种对柚木细根周转过程的影响尚不清楚。本项目按照项目计划书确定的研究内容和开展时间，完成一下研究任务，包括：1）施肥方式（撒施、沟施、淋施和袋妆混施）对柚木细根分布的时空变异性的影响研究；2）不同C/N比施肥对柚木细根的生理生化影响研究；3）柚木细根周转速度受施肥种类的影响研究。研究内容按照计划执行，工作量基本完成。.通过以上内容开展，研究目标基本完成。一是得到了不同施肥方式和种类下柚木根系的空间分布，细根动态；二是构建了良好根系构型和养分利用的高效施肥制度；三是初步评估了柚木细根周转受施肥的影响。四是统计得到柚木具有药理活性成分92种。.项目得到了不同施肥方式下的根系分布、细根生长与死亡动态，建立了形成良好根系构型和养分利用关键期的高效施肥制度；初步评估了不同施肥下的细根周转，丰富细根周转的影响，为氮沉降背景下的土壤养分循环和碳循环研究提供一定的依据。在生产上，形成的高效施肥方案可较大幅度提高柚木生长速度（单株蓄积量提高40%）。.