通过对格氏栲（Castanopsis kawakamii）和杉木（Cunninghamia lanceolata）人工林新近凋落物、半分解层（F层）和分解层（H层）凋落物室内模拟淋洗实验，研究了凋落物淋溶过程中溶解有机碳（DOC）浓度变化及紫外-可见（UV-Vis）光谱特征。结果表明，格氏栲和杉木人工林新近凋落物淋出液的DOC浓度较低，F层淋出液的DOC浓度较高；格氏栲凋落物淋出液的DOC浓度基本上随淋溶次数的增加而降低，杉木的则先升后降。淋出液溶解有机物（DOM）的紫外吸收值均随波长的增加而减小，且UV-Vis吸收曲线均在200nm附近出现吸收峰，不同来源DOM 的E240/E420存在显著差异；同一样品各次淋出液的DOC浓度与E200有很好的线性关系（R2>0.90），据此，可用E200值估算DOC浓度。

Fine root (<2mm in diameter) distribution, seasonal pattern and net production were studied during 1999-2001 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. Fine root biomass and necromass were determined by soil coring at a bimonthly interval. Soil cores were divided into 10 depths: 0～10, 10～20, 20～30, 30～40, 40～50, 50～60, 60～70, 70～80, 80～90, and 90～100cm. Litter bags (18×18cm2 size, 0.25mm mesh) were used in determination the decay rates of fine roots (<0.5mm, 0.5-1mm, and 1-2mm). Mean annual fine-root production, mortality, decomposition and turnover rate were calculated by the compartment-flow method. Mean fine-root biomass ranged from 1.49 Mg ha-1 in the CF to 4.94 Mg ha-1 in the NF, and decreased in the following order: NF>CK>FH>OX>CF. There were significant seasonal changes of biomass and necromass in all stands (P<0.05), while no significant yearly fluctuations were detected (P>0.05). In all stands, an early spring (March) peak of fine root biomass was found, and the minimum value occurred mainly in dry summer or cold winter. For the NF, 59.8% of fine root biomass was found in the top soil of 0-10 cm, a layer that maximum difference of depth distribution among all stands occurred, where fine root biomass of the NF was 2.37 times, 3.55 times, 8.12 times, and 7.12 times as much as those of the CK, FH, CF, and OX, respectively. Percentages of original mass lost during the first year of decomposition ranged from 43% to 56% for the FH to 68% to 80% for the NF. Mean annual root decomposition, mortality and production ranged from 8.47 Mg ha-1 a-1, 8.63 Mg ha-1 a-1 and 9.5 Mg ha-1 a-1 in the NF to 2.50, 2.49 and 2.51 Mg ha-1 a-1 in the CF, ranked as NF>CK>FH>OX>CF. The mean root turnover rate ranged from 1.48 a-1 in the FH to 1.78 a-1 in the NF.

杉木（Cunninghamia lanceolata）是我国南方最主要的造林树种之一，由于其速生丰产，在我国南方林区得到很大的发展，但随着连栽代数不断增加，地力衰退日趋严重［1-3］。我国南方用于造林的主要树种大多集中于杉木、马尾松等有限的几个树种，出现了杉木连栽地力衰退及杉木用途的受限等问题，因此，寻找速生丰产又能维持地力的造林树种，在一定范围内替换杉木，已成为南方林区实现林地可持续经营的重要措施之一。福建柏（Fokienia hodginsii Henry et Thomas），又称建柏，是我国的特有种，树形美观，树干通直，生长快，材质好，具有较高的经济、生态和美学价值［］。各地造林实践和研究报道认为，在中等或较差的立地条件下，福建柏的生长速度可以超过杉木［4-6]，而福建柏与杉木、檫树、樟树树等组成混交林还可促进目的树种的生长［］。本课题组自1999 年起，选择莘口教学林场1967 年在小湖工区营造的较大面积的福建柏和杉木人工林，对两种林分的凋落物和细根特性，凋落物和细根分解及养分释放过程，C 吸存与流动及树种自我培肥地力能力等进行了系统研究。通过对福建柏和杉木人工林生物学与生态学特性差异进行比较，试图为探讨福建柏在一定范围内替换杉木的潜力提供理论依据。

通过对福建三明格氏栲天然林及在其采伐迹地上营造的33年生格氏栲人工林和杉木人工林粗木质残体现存量与季节动态、C库及养分库的研究表明，格氏栲天然林、人工林和杉木人工林枯枝落叶层现存量分别为1.32、0.46和0.23t·hm-2.3种林分粗木质残体现存量的季节变化模式均为夏季>冬季>秋季>春季。格氏栲天然林粗木质残体C贮量0.78 t·hm-2，分别是格氏栲人工林和杉木人工林的4.11倍和7.09倍；格氏栲天然林粗木质残体C库与两种人工林间差异显著（P<0.05）。格氏栲天然林、格氏栲人工林和杉木人工林粗木质残体养分贮量分别为14.16、2.90和0.95kg·hm-2；格氏栲天然林粗木质残体中各种养分贮量均最高。与人工林相比，天然林粗木质残体现存量、C和养分贮量均最大。

通过对福建三明36a生的格氏栲人工林和杉木人工林林木地下C分配（TBCA）进行研究，结果表明，由分室累加法直接测定的格氏栲和杉木人工林的TBCA分别为8.426 和4.040tC·hm-2·a-1。在格氏栲和杉木人工林TBCA组成中，根系净生产量和根系呼吸各约占50%；在根系年净生产量中，细根年净生产量和粗根年净生产量各约占75%和25%。而格氏栲和杉木人工林的细根年C归还量则均约占各自TBCA的1/3（分别为33%和36%）。在假设地下C库处于稳定状态时，由C平衡法计算的格氏栲和杉木人工林的TBCA（分别为6.039 和2.987tC·hm-2·a-1）低于分室累加法，这与两种人工林地下C库尚未达到稳定状态有关。利用Raich and Nadelhoffer（1989）全球模式方程推算的格氏栲和杉木人工林的TBCA（分别为9.771和5.344tC·hm-2·a-1）则高于分室累加法，这与全球模式方程只是一种全球尺度规律有关。