申请人从事林木细根对土壤有机质作用研究：①对源于温带森林的细根研究方法进行改进，提出了适用于湿润亚热带森林的细根取样和细根周转估计方法，提高了细根周转的估计精度，定量了细根周转对土壤有机物归还的贡献。②揭示了湿润亚热带森林转换和杉木人工林生长对细根周转及土壤有机质的作用，发现了林龄对地下过程关键参数的影响。③提出了森林碳分配机制和地下碳分配概念模型，揭示了森林地下碳分配对细根生产量和土壤有机质的调控作用。结果加深了对森林根系—土壤肥力关系的认识，为森林土壤有机质调控提供了新的理论框架。④发表SCI论文20篇，其中在Global Change Biology, New Phytologist, Forest Ecology and Management等发表第一作者论文6篇，1篇投Plant and Soil的共同通讯作者论文正在修改之中。获省科学技术奖一等奖（排名第二）1项，发明专利1项。

The applicant focused on effects of tree fine roots on soil organic matter pool. The main achievements are as follows: (i) The root study methods derived originally from temperate forests were improved and fine-root sampling strategy and fine-root turnover estimation method that adapted to humid subtropical forests were proposed, so that annual fine-root turnover was accurately assessed and its contribution to soil carbon input was quantified. (ii) The effects of both conversing natural forests into plantation forests and stand development of Chinese fir plantations on fine-root turnover and soil organic matter were indicated, and the influences of stand age on some key parameters of belowground processes were revealed. (iii) The mechanisms on carbon allocation in forest ecosystems were improved by proposing an integrated allocation scheme including an allometric constraint and three trade-offs among GPP components and a hypothesized belowground carbon allocation model. Meanwhile, the controls on fine-root production and soil organic matter exerted by belowground carbon allocation were also elucidated. These results advance our understanding on the coupling between fine roots and soil fertility and provide a new theoretical framework toward managing soil organic matter pool in forest ecosystems. (iv) The applicant has published 20 SCI papers, including 6 first-authored papers on the mainstream journals such as Global Change Biology, New Phytologist, Forest Ecology and Management, etc, with 1 co-correspondance-authored paper submitted to Plant and Soil being revised. He also won the first prize of Fujian Science and Technology Award (ranked second) and got one National Invention Patent.

为了揭示全球变暖、氮沉降和降雨减少及其交互作用对杉木人工林细根周转和林木生长的影响，在福建省三明市陈大国有林场开展杉木幼苗土壤增温和氮添加、土壤增温和隔离降雨两个双因子试验，用微根管法监测细根的生产、死亡和细根寿命，采用内生长环法等测定杉木幼苗细根形态特征、生态化学计量学、细根代谢特征，采用13CO2标记技术测定新近光合产物地下碳分配，并揭示增温对杉木细根寿命的影响机理。通过两年多的定位观测，获得了以下研究结果：（1）土壤增温均促进了细根年生产量、死亡量和周转速率，而氮添加仅在第二年促进了细根年生产量、死亡量和周转速率；但增温和氮添加间没有存在显著的交互作用。（2）土壤增温和隔离降雨对杉木细根生产量有显著的负交互作用。土壤增温在未隔离降雨条件下促进了细根生产量，但在隔离降雨条件下则对细根生产量没有显著影响；隔离降雨在未增温条件下对细根生产量没有显著影响，但在增温的条件下则显著降低细根生产量。在单独土壤增温或单独隔离降雨的处理中，土壤发生适度的干旱，杉木幼苗通过根细根向深层土壤分布或是增加向细根的碳分配以弥补增温引起的细根加速死亡，从而能够维持不变的细根生物量而能够适应这种适度的干旱，并能够维持苗木生长。而在同时增温和隔离降雨的处理中，土壤干旱程度增加，由于细根生产量弥补细根死亡量的增加，细根生物量降低，导致苗木生长量下降。该研究结果表明温度和降雨的交互作用在控制热带亚热带森林生产力具有重要作用。（3）土壤增温显著降低了细根的寿命。其可能机制有：增温后地上和地下碳源汇关系发生变化、地上和地下生长失去协调性，新近光合产物向细根的供应速率降低；增温后细根呼吸未出现驯化、导致细根非结构性碳消耗加快；细根组织内N富集，N:P比严重失衡有关。研究成果可为气候变化条件下杉木人工林生产力的科学预测、适应性管理等提供基础数据和理论支持。