抚育强度对天然针阔混交林细根化学计量及根系呼吸的影响

Effects of Tending Intensity on Stoichiometry and Root Respiration of Fine Roots in Natural Coniferous and Broad-leaved Mixed Forest

以小兴安岭带岭林业局东方红林场天然针阔混交林为试验区,设置6块不同间伐强度(10%、15%、20%、25%、30%、35%)样地和1块对照样地;采用土钻法、挖壕断根法、重铬酸钾法等化学法测量地下细根生物量、根系呼吸及细根养分质量分数,对间伐后的各项指标进行差异性分析,运用逐步回归法确定各指标对根系呼吸的贡献程度。结果表明:对照样地细根生物量、N、K质量分数、w(N)∶w(P)及根系呼吸速率最高;25%间伐强度的C质量分数最高;间伐强度35%的P质量分数、w(C)∶w(N)最高;15%间伐强度的w(C)∶w(P)最高。逐步回归结果显示根系呼吸与w(C)∶w(N)呈负相关,与间伐强度呈正相关,即间伐强度越大,根系呼吸速率越大。

Six plots with different thinning intensities(10%,15%,20%,25%,30% and 35%) and one normal plot were set up in the natural coniferous and broad-leaved mixed forest of Dongfanghong Forest Farm led by Xiaoxing’an Mountains.The biomass,respiration and nutrient content of fine roots were measured by soil drilling,digging and potassium dichromate method.The difference of each index after thinning was analyzed and the contribution degree of each index to root respiration was determined by stepwise regression method.The results showed that the biomass,N,K content,N/P and respiration rate of fine roots were the highest.The C content in 25% thinning intensity was the highest.P content and C/N were the highest in 35% and C/P was the highest in 15% thinning.By stepwise regression,the root respiration was negatively correlated with C/N,and positively correlated with thinning intensity,that is,the higher the thinning intensity is,the higher the root respiration rate is.