摘要
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土壤非保护性有机 C含量及分配的研究 ,结果表明 ,格氏栲天然林 0～ 10 0 cm土层内土壤有机 C贮量分别是格氏栲人工林和杉木人工林的 1.17倍和1.35倍 ,轻组有机 C贮量分别是后两者的 1.6 4倍和 2 .16倍 ,而颗粒有机 C贮量则分别是后两者的 1.6 0倍和 3.4 3倍 ,其土壤轻组有机 C和颗粒有机 C的分配比例亦显著高于后两者。不同林分间差异均以 0～ 10 cm土层为最大 ,该层格氏栲天然林土壤有机 C含量分别是格氏栲和杉木人工林的 1.5 2倍和 1.6 3倍 ,轻组有机 C含量分别是后两者的 1.70倍和 2 .14倍 ,而颗粒有机C含量则分别是后两者的 2 .18倍和 4 .85倍。这种差异与经营人工林时进行皆伐、炼山、整地等对林地干扰强度较大、幼林郁闭前产生水土流失及凋落物、枯死细根归还量减少等有关。土壤轻组有机 C和颗粒有机 C可作为土壤有机 C库变化的较为敏感指标 ,同时亦可指示土壤肥力演变。
Soil organic carbon (SOC) pool plays an important role in mitigating the rise of atmospheric CO_2. Due to its relatively unprotected (biochemical and physical) status, the unprotected SOC, be measured as either the light fraction (LFOC) or particulate organic carbon (POC), is sensitive to management practices and could contribute highly to rise in atmospheric CO_2 when inappropriate managements are employed. In South China, large-scale native forests have been converted to fast-growth and high yield commercial forest plantations in the last decades. Some silvicultural measures, such as planting pure stands, clear-cutting and slash-burning, have been widely applied during this conversion. In addition to soil degradation and yield decline, there are considerable concerns about the changes in pool of SOC, especially of unprotected SOC, following the conversion of natural forests into plantation forests. We chose a natural forest of Castanopsis kawakamii (NF), a (C. kawakamii) plantation forest (CK), and a Chinese fir (Cunninghamia lanceolata) (CF) plantation forest in Sanming nature reserve, Fujian, China, to assess changes in SOC, and those in LFOC and POC as well.The NF had a SOC pool of 123.88 t/hm^2 in the 100 cm soil profile, of which 13.43% and 23.22% appear as LFOC and POC, respectively. Compared with NF, CK and CF had reduced SOC pool by 14.5% and 25.9%, soil LFOC pool by 39.0% and 53.7%, and soil POC pool by 37.5% and 70.8%, respectively. Moreover, CK and CF had lower proportion of SOC as either LFOC (9.57% and 8.37%) or POC (16.96% and 9.11%) than NF. The maximum differences of unprotected SOC among forests occurred in the 0～10 cm soil layer, where the NF had SOC, LFOC, and POC contents of 29.67 g/kg, 8.95 g/kg and 11.94 g/kg, respectively, being as much 1.52 times, 1.70 times, and 2.18 times as that in CK, and 1.63 times, 2.14 times, and 4.85 times as that in CF, respectively. The contents of soil LFOC and POC were highly correlated with the amounts of living fine roots and soil macro-aggregates. The intense disturbance of surface soil from clear-cutting, slash-and-burning, and soil preparation etc, the serious soil erosion prior to canopy closure, and the reduction in detritus input through litterfall and fine root turnover might be responsible for the decrease in both SOC and unprotected SOC pools of monoculture plantations. The high correlations of LFOC and POC with total N, total P, hydrolysable N and available P indicated that the unprotected SOC can serves as a good indicator for soil fertility. The sensitivity index to changes were much higher for LFOC (1.27) and POC (2.59) than for total SOC (0.41) also makes unprotected SOC a good predictor of changes in SOC pool.
出处
《生态学报》
CAS
CSCD
北大核心
2004年第1期1-8,共8页
Acta Ecologica Sinica
基金
教育部高校优秀青年教师教学科研奖励计划资助项目
福建省基础研究重大资助项目 (2 0 0 0 -F-0 0 4)~~
关键词
天然林
人工林
土壤非保护性有机C
轻组有机C
颗粒有机C
natural forest
monoculture plantations
unprotected soil organic carbon
light fraction
particulate organic carbon
