通过对中亚热带格氏栲天然林（natural forest of Castanopsis kawakamii，约150年）、格氏栲和杉木人工林（monoculture plantations of C. kawakamii and Cunninghamia lanceolata，33 年生）凋落物数量与季节动态、养分归还及凋落叶分解与其质量的关系为期三年（1999～2001）研究表明，林分年均凋落量（t•ha-1）及叶所占比例（%）分别为：格氏栲天然林11.01，59.70；格氏栲人工林9.54，71.98；杉木人工林5.47，58.29。格氏栲天然林与人工林凋落量每年只出现1次峰值（4月），而杉木林的则出现3次 （4或5月、8月和11月）。除杉木林的Ca和格氏栲人工林的Mg年归还量最大外，N、P、K 及养分总归还量均以格氏栲天然林的为最大，杉木人工林的最小。分解1年后格氏栲天然林中格氏栲叶的干重损失最大（98.16%），杉木叶的最小（60.78%）。C/N及木质素/N比值与凋落叶分解速率呈显著负相关，而N、水溶性化合物初始浓度与分解速 率呈显著正相关。与针叶树人工林相比，天然林的凋落物数量大、养分归还量高、分解快，具有良好自我 培肥地力的能力。因此，保护和扩大常绿阔叶林资源已成为南方林区实现森林可持续经营的重要措施之一。

Decomposition of fine roots (<2 mm in diameter, viz. <0.5mm, 0.5-1.0mm, 1.0-2.0mm) was studied by means of litter bag in a mixed forest of Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) and Tsoong's tree (Tsoongiodendron odorum Chun) in Sanming, Fujian, China. In a 540 d period of decay, fine roots in all litter bags decomposed in a three-phase manner: (a) for the Chinese fir, an initial, relatively low rate of decay up to 90 d followed by a period of rapid weight loss until 270 d, and then by a phase of slow decay rate; (b) for the Tsoong's tree, a rapid loss period between 0-60 d followed by a relatively rapid loss period between 60-360 d, and then a slow loss period between 360-540 d occurred. The mass loss after 1 yr of decomposition ranged from 58.5% to 63.3% for the Chinese fir and 68.8% to 78.2% for the Tsoong's tree. Fine roots with a larger diameter had a lower rate of mass loss. Consistent increase in lignin concentration and decrease in absolute amount of phosphorus (P) were found for fine roots of the two tree species during decomposition. The absolute amounts of nitrogen (N) increased a little initially in the fine roots of the Chinese fir during a short duration. In contrast, the fine roots of Tsoong's tree were releasing N from the outset. The chemical composition controlled decomposition rate and it was found a change of TNC (total nonstructural carbohydrates)-regulating in the initial decomposition phase to lignin- or N-regulating in the second phase, and P- or lignin-regulating in the last phase.

The amount and pattern of litterfall, its nutrient return, initial chemistry of leaf litter, and dynamics of N, P and K associated with leaf-litter decomposition were studied in 33-year-old plantations of two coniferous trees, Chinese fir (Cunninghamia lanceolata, CF) and Fokienia hodginsii (FH), and two broadleaved trees, Ormosia xylocarpa (OX) and Castanopsis kawakamii (CK), and compared with that of an adjacent natural forest of Castanopsis kawakamii (NF,～150 year old) in Sanming, Fujian, China. Mean annual total litterfall over 3 years of observations was 5.47 Mg•ha-1 in the CF, 7.29 Mg•ha-1 in the FH, 5.69 Mg•ha-1 in the OX, 9.54 Mg•ha-1 in the CK and 11.01 Mg•ha-1 in the NF respectively; of this litterfall, leaf contribution ranged from 58% to 72%. Litterfall in the OX, CK, and NF showed an unimodal distribution pattern, while for the CF and FH, the litterfall pattern was multi-peak. The highest annual Ca and Mg returns were noticed in the FH and in the CK, respectively. The amounts of N, P, and K which potentially returned to the soil were the highest in the NF. The loss of dry matter in leaf litter exhibited a negative exponential pattern during the 750-day decomposition. Using the model xt=A+Be-kt, the annual dry matter decay constants (k) ranged from 1.157 in CF to 4.619 in OX. Initial lignin concentration and lignin/N ratios showed significantly negative correlations with k (r=-0.916, P=0.011; r=-0.473, P=0.041), whereas initial N concentration showed low positive correlations (r=0.225, P=0.038). Using the model xt=A+Be-kt, the decay constant of N (kN) ranged from 0.769 in CF to 4.978 in OX; the decay constant of P (kP) ranged from 1.967 in the OX to 4.664 in the NF; and the decay constant of K (kK) seemed very similar among these forests (5.250-5.992). The decay constants of nutrients during leaf-litter decomposition can be arranged in the sequence of kK>kP>kN, except for leaf litter of OX where kK>kN>kP.

通过对福建三明相邻的27年生混交比例为2行杉木和1行观光木的混交林和杉木纯林群落细根分布特点的研究，结果表明，杉木和观光木行间的杉木细根密度虽比杉木与杉木行间的低8.5%，但观光木与杉木之间的观光木细根密度则比杉木与杉木行间的高152.09%，其细根总密度比杉木与杉木行间的大10.43%。混交林杉木各径级活细根密度呈单峰型分布，均以5-10cm土层最大；而观光木各径级活根主要分布在0-10cm土层内。纯林杉木各径级活细根密度亦基本呈单峰型分布，但峰值出现在10-20cm或20-30cm土层。不同树种不同径级死细根的分布均与其各自的活细根分布相似。混交林灌木细根密度在30-40cm最大，而纯林灌木细根集中于表层0-10cm；混交林和纯林草本细根均集中在0-5cm土层。与纯林的相比，混交林中杉木细根主要分布层次明显上移，混交林群落表层土壤细根所占比重增大，这对土壤资源高效利用及促进群落生产力提高有利。

通过福建省中亚热带杉木观光木混交林和杉木纯林凋落物的分解和养分释放动态试验研究表明，凋落物各组分分解过程中干物质重损失速率随时间而减小，分解1年时以观光木叶的干重损失最大。各组分分解过程中N、P元素浓度增加而K和C元素浓度下降。混交林中各组分的养分释放速率大小为观光木叶>混合样品（等重量的观叶和杉叶混合）>杉叶>杉小枝。不同元素的释放速率与干重损失速率大小为：K>C>干重>N≈P。混交林凋落物的年养分释放量（kg•hm-2•yr-1）为N17.921，P0.715，K10.315，分别是纯林的2.03倍、1.73倍和1.34倍。与纯林相比，混交林较高的年凋落物养分归还量和养分释放量有利于促进养分的再循环，这对维持混交林的地力有重要作用。