格氏栲天然林与人工林粗木质残体碳库及养分库

Carbon and Nutrient Pools of Coarse Woody Debris in a Natural Forest and Plantation in Subtropical China

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粗木质残体现存量分别为1 32、0 4 6和0 2 3t·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贮量为0 78t·hm- 2 ,分别是格氏栲人工林和杉木人工林的4 1 1倍和7 0 9倍;格氏栲天然林粗木质残体C库与2种人工林间差异显著(P <0 0 5)。格氏栲天然林、人工林和杉木人工林粗木质残体养分贮量分别为1 4 1 6、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。

During the past decades, large scale natural forests had been converted to fast growing and high yield commercial plantations to meet the demands for timber, fuel material, and other forest products. Some silvicultural measures, such as planting pure stands, clear cutting and slash burning, were widely applied during this conversion. Yield decline and land deterioration in such disturbed ecosystems had become serious. In this context, the ecological comparisons between natural forests and plantations have special implications for sustainable management. Coarse woody debris (CWD) as an important pool of carbon and nutrients also plays a substantial role in several ecological processes in forest ecosystems. However, few studies on CWD have been conducted in natural and planted forests under same climatic and edaphic conditions in subtropical China.The standing crop and seasonal dynamics of CWD, its carbon and nutrient stocks were studied in a natural forest of Castanopsis kawakamii (NF) and adjacent plantations of C. kawakamii (CK) and Chinese Fir( Cunninghamia lanceolata, CF) in Sanming, Fujian, China. CWD masses were 1 32 t·hm -2 in the NF, 0 46 t·hm -2 in the CK and 0 23 t·hm -2 in the CF respectively. The standing crop of CWD in three forests showed similar seasonal trend as follows: summer > winter > autumn > spring. Carbon storage in CWD of the NF was 0 78 t·hm -2 , being 4 11 times and 7 09 times as much as that of the CK and the CF, respectively. Significant difference in C stocks of CWD was found between NF and CK (or CF) ( P <0 05). Nutrient storage in CWD ranged from 14 16 kg·hm -2 in the NF to 0 95 kg·hm -2 in the CF. The amounts of N, P, K, Ca and Mg storage were the highest in CWD of the NF. The results of this study demonstrate that the natural forest has a greater capability for maintaining site productivity than plantations due to higher CWD mass coupled with greater carbon and nutrient pools. Therefore, conservation of the natural forest is recommended as a practical measure in forest management to realize sustainable development of forestry in mountainous areas of southern China.