东莞主要森林群落凋落物碳储量及其空间分布

基于2 km×2 km的UTM网格对东莞市不同的森林群落类型进行了详细调查,以研究森林凋落物的碳储量及其空间分布.研究结果表明,天然林凋落物碳储量显著高于人工林;不同森林类型的凋落物碳储量之间差异极显著,其碳密度大小依次为:湿地松-阔叶混交林>相思林>马尾松-杉木林>荷木林>桉树林>杉木-阔叶混交林>马尾松-阔叶混交林>荔枝-龙眼林>青皮竹林.针叶林的单位凋落物碳含量最大,占59%,大于阔叶林;相思林和荷木林单位凋落物碳含量仅次于马尾松-杉木针叶林.不同的经营措施对森林凋落物碳储量有显著的影响,经封山育林的林分凋落物碳储量最大.坡位对凋落物碳储量也有显著的影响,随着坡位的降低,森林凋落物现存量和碳密度随之降低.东莞市森林凋落物碳密度为4.25±0.15 t/hm2,凋落物碳储量总量为0.23±0.008 Mt.凋落物的碳储量动态直接关系到土壤碳储库,采取合适的经营措施,减少人为干扰造成的凋落物的流失,最终对于提高本地区森林生态系统碳库会有积极作用.

Organic Carbon Storage and Its Distribution in Forest Litters among Forest Communities in Dongguan,South China

In this study, forest litter organic carbon storage and density among forest communities were estimated based on a forest survey in Dongguan, south China. Filed sampling was carried out based on a 2 km×2 km grid system overlaid on the topographic map of the forest land in Dongguan. The results showed that the litter of natural forests contained significantly more organic carbon than that of artificial forests, which was assessed by One-way ANOVA using STATISTICA 8.0; and the litter organic carbon density among the 10 types of forests classified by their dominant trees were significantly different with each other. The order of the litter carbon density from large to small is: Pinus elliottii & broad leaf forest > Acacia magium > Pinus massoniana and Cunninghamia lanceolata > Schima superba > Eucalyptus exserta > Cunninghamia lanceolata & broad leaf forest> Pinus massoniana and broad leaf forest > Litchi chinensis and Dimocarpus longan > Bambusa textilis. In addition, coniferous forest litter contained 59% of carbon per unit mass, more than that of broadleaved forests. The second largest litter carbon content per unit mass existed in the forests dominated by Acacia magium and Schima superba. Litter organic carbon storage was also influenced by forest management regimes. Closing the mountain for forest rehabilitation led to higher level of litter organic carbon density. There was no significant influence among different slopes and different aspects. However, different positions on slopes were found to have significant influence on the litter organic carbon density. The highest level of litter organic carbon density was found on the ridge of the hill. The total litter organic carbon pool was estimated as 0.23±0.008 Mt, and the average litter organic carbon density was 4.25±0.15 t/hm2. The dynamics of litter organic carbon are closely related to the soil organic carbon pool. Therefore, appropriate measures should be taken to prevent the ecosystem from the decrease of litters by human activities, which will be useful for increasing the carbon pools of the study area.