摘要:
该文研究了原始红松阔叶林当年形成的凋落物层中表层和底层红松枝叶分解速率和C、N、P、K等养分元素的释放方式.结果表明,凋落物底层的微环境可以加速凋落物的分解和养分元素的释放.枝的失重率和养分元素释放率要显著低于叶.随着分解试验时间延长,分解速率(k值)逐渐降低,在所有分解阶段内表层枝叶的分解速率均小于底层枝叶.红松枝叶失重率与木质素、纤维素、C/N和木质素/N有关,同一时间段内影响凋落物表层和底层枝叶失重率的化学成分有所区别.但在分解后期失重率主要与木质素浓度相关.表层枝叶N和P的净固化率高于底层枝叶而净矿化率则低于底层枝叶.K在红松枝叶的分解过程中一直进行矿化作用,并且表层枝叶K元素的剩余百分率大于底层枝叶,枝中K元素剩余百分率大于叶.结果说明在红松阔叶林凋落物分解研究中如果忽视凋落物层微环境效应将会低估红松针叶分解速率和N、P、K的释放率.
Abstract:
The effects of forest litter layer on litter decomposition were examined by the measurement of mass remaining and N,P,K release after three years' exposure of Korean pine(Pinus koraiensis Sieb.et Zucc.) needles and twigs placed on and under the litter layer formed by the litter fall in the present year in natural P.koraiensis broadleaved forests.The microenvironment below the litter layer contributes to the decomposition rate and N,P,K release rates of the litter,but needles showed a significant higher decomposition rate and N,P,K release rates than those of twigs.The decomposition rate(k value) decreased continuously with the length of study period extended,and the k values were higher for needles and twigs on the litter layer than those under the layer.The mass remaining percentage of litter in this study was related to C/N,lignin/N,and the concentration of lignin and cellulose,but needles and twigs on the litter layer were regulated by litter chemical components from those under the litter layer.At later decomposition stage,lignin became the dominant factor affecting the litter decomposition for all litter types.Needles and twigs on the litter layer exhibited a higher N and P immobilization rate and lower mineralization rate compared with those under the layer.K was continuously mineralized during the study period and its mineralization rate was higher for needles than twigs as well as for needles and twigs under the layer than those on the layer.Our study proved that decomposition rate and C,N,P,K release rates of P.koraiensis would be underestimated if the microenvironment effects of litter layer were not taken into account.
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