连栽对尾巨桉短周期人工林碳贮量的影响

Effects of continuous cropping on the carbon storage of Eucalyptus urophylla×E.grandis short-rotations plantations

对广西国有东门林场不同连栽代数尾巨桉(Eucalyptus urophylla×E.grandis)短周期人工林生态系统碳贮量开展研究,旨在阐明短周期桉树人工林连栽对生态系统各组分(土壤、凋落物、林下植物和乔木)的碳含量、碳贮量及其分配格局的影响。结果表明:(1)尾巨桉短周期人工林生态系统同一层次的同一器官(或组分)碳含量因连栽代次和林龄不同存在差异,但差异不显著(p>0.05);而不同层次和不同器官(或组分)碳含量的差异极显著(p<0.01),表明人工林生态系统的物种组成及其特性对碳含量的影响更显著。(2)7.6a尾巨桉连栽林分的碳贮量平均为127.649 t.hm-2,比第1代(134.411 t.hm-2)低5.03%,差异不显著(p>0.05);两类林分碳贮量的空间分布序列均表现为土壤层>乔木层>凋落物层>林下植物层。(3)两类林分各组份的碳含量和碳贮量均随着林龄的增加而增加。(4)连栽对乔木层和凋落物层的碳贮量影响较小,但具有降低林下植被和土壤碳贮量的作用。短周期桉树人工林连栽采取的采伐林木、炼山清理、机耕全垦整地等措施对林地的反复干扰是导致林下植被和土壤碳贮量下降的主要原因。

Plantations of Eucalyptus urophylla×E.grandis in the Dongmen National Forest farm of Guangxi were studied over an eight-year management period to determine the effects of continuous short-rotation cropping on the subsequent carbon content in these ecosystems.The carbon sequestration rates and storage,and how carbon is distributed across the ecosystem components were examined for pattern changes as a result of management.The components studied include soil,litter,undergrowth,and tree layers.The results of the research showed：（1）There are differences between the carbon content of the same component in the same layer of short-rotation Eucalyptus urophylla×E.grandis plantation because of continuous cropping and the stand ages.but no significant differences were found（p0.05）;there are significant differences for the carbon content of different layers and component（p0.01）,it shows that the species composition of plantation and its characteristics have great impact on carbon content.（2）The average carbon storage of 7.6a continuous Eucalyptus urophylla × E.grandis short-rotation cropping plantation is 127.649 t·hm-2,and was 5.03% lower than that of the first generation（134.411 t·hm-2）,no significant difference was found within each layer between the first and second generation（p0.05）;Significant differences were found between the different layers in the order of soil layer tree layer litter layer undergrowth layer,（3）Carbon content of two generation increases as the plantation ages increase.（4）Continuous cropping has the potential to influence the patterns of carbon accumulation and storage in Eucalyptus urophylla x E.grandis plantations by increasing the percentage of stored carbon in tree and litter layers,and decreasing the percentage in the undergrowth and soil layers.The main reasons of decreasing carbon in the undergrowth and soil layers are the continuous disturbance of falling trees,mountain smelting and tractor plowing in continuous Eucalyptus urophylla x E.grandis short-rotation cropping.