摘要
198 7～ 1999年 ,在江西省分宜县南京中医药大学亚热带林业实验中心 ,对 9a生的杉木人工林 ,进行了不同保留密度的管理。设立 6个固定样地 ,对林下植被变化作了 13a的连续观测 ,土壤肥力变化作了 9a变化测定 ,并对水土流失、枯落物量及其分解速率进行了 8a的测定。结果表明 ,凡经间伐的林分 ,林下植被获得了良好发育 ,13a中林下植被种类达到了 30～ 36种 ,盖度达到 80 %～ 90 % ,而生物量达到 5t·hm- 2 以上。未经间伐密度较大的林分林下植被发育较迟 ,比间伐林分推迟 8～ 9a。适度间伐不会产生不利于地力维护的水土流失 ,合理的林分密度管理可提高微生物数量 ,达 2 .42倍。林分密度低而林下植被发育好的林分 ,枯落物分解速度快。杉木中龄林阶段 ,土壤有机质含量有所下降 ,特别是 16～ 30cm的土壤 ,水解N和速效P含量下降 ,速效N下降最明显。林分密度大 ,生长量大的林分 ,速效N、P下降幅度也大。因此 ,通过间伐适当降低林分密度 ,对维护土壤肥力有较大作用 。
Since 1987 to 1999, a study on the density management of Chinese fir plantations of 9 year old was made continuously in the Experimental Center for Subtropical Forestry under the Chinese Academy of Forestry (CAF) located in Fenyi County, Jiangxi Province. Based on the establishment of 5 fixed sample plots in the stands with different retained density after thinning, the undergrowth vegetation had been observed for 13 years, the soil fertility in the stands had been tested for 9 years, the soil erosion as well as the amount of litters and their decomposition rates had been monitored for 8 years in the stands. The results showed that in all thinned stands with different thinning intensity, the undergrowth vegetation had developed very well, with the number of undergrowth plant species being increased to 30～36 species, the coverage of undergrowth vegetation being increased to 80%～90% , and the biomass of undergrowth vegetation being increased to 5 t·hm -2 in 13 years, while in the dense stand without thinning the undergrowth vegetation developed poorly and 8～9 years later to reaching the same level than that in the thinned stands. The reasonable stand density management could also increase the amount of micro organisms by 2.42 times in the soil, which resulted in faster decomposition of litters in the stands with lower density and well developed undergrowth vegetation. Generally, when the Chinese fir plantation grows into the middle aged, the content of organic mater starts decreasing more or less in the soil, particularly in the soil layer at depth of 16～30 cm underground , the content of available nitrogen and phosphorous decrease significantly. So, in the dense and fast growing stands, the higher the stand density is , the more the available nitrogen and phosphorous decrease significantly in the soil. Therefore, the reasonable decreasing of stand density by means of thinning can conserve the soil fertility, so that the long term productivity of forest land can be maintained.
出处
《林业科学》
EI
CAS
CSCD
北大核心
2001年第5期2-9,共8页
Scientia Silvae Sinicae
基金
国家自然科学基金重点资助项目"杉木按树人工林长期生产力保持机制的研究"(批准号 :396 30 2 40 )
关键词
密度管理
林下植被
水土保持
土壤肥力
杉木林
人工林
长期生产力
Chinese fir ( Cunninghamia lanceolata ) plantation, Stand density management, Undergrowth vegetation, Soil fertility
