间伐对杉木凋落物分解中生态化学计量的影响

以福建杉木人工林为研究对象,采用不同间伐强度(23%、32%、不间伐),研究间伐后不同密度样地内凋落物分解过程中的C、N、P含量及其化学计量比特征的影响。结果表明:(1)各处理叶和枝的C、N、P含量在整个分解过程中均以下降-上升的波动下降;凋落物分解1 a后,3种处理叶和枝的N、P含量以D2(弱度间伐)处理最低,叶C含量D2处理最低,枝C含量D1(强度间伐)处理最低,且D1和D2处理的叶C和叶N含量显著低于对照CK(P<0.05),D1处理的枝C含量显著低于D2和CK处理(P<0.05),3种处理的枝N含量有显著差异(P<0.05);(2)凋落物分解1 a后,2种间伐密度处理的叶和枝C︰N与对照处理CK有显著差异(P<0.05),3种处理之间叶和枝的C︰P、N︰P无显著差异(P>0.05);(3)叶C与叶N、叶C︰N,叶N与叶P均呈显著正相关,叶C与叶P呈极显著正相关;叶C︰N与叶N︰P呈显著负相关;枝C与枝P,枝N与枝N︰P呈显著正相关;枝C︰N与枝N︰P呈显著负相关;枝N与枝C︰N,枝P与枝C︰P呈极显著负相关。弱度间伐在分解240 d显著增加了枝C︰N和枝C︰P,在分解360 d时显著降低了叶C︰N,增加了枝C︰N;在整个分解过程中,弱度间伐处理对N︰P无显著影响。强度间伐在凋落物分解60 d显著降低了枝C︰N、枝C︰P和枝N︰P,在分解300 d显著降低了叶C︰P,在360 d显著降低了枝C︰N;在整个分解过程中,强度间伐对叶N︰P无显著影响。

Effect of Thinning Intensity on Ecological Stoichiometry in Litters Decomposition of Cunninghamia lanceolata

Taking Cunninghamia lanceolata as research object,the effects of different thinning intensities(23%,32%and no thinning)on the C,N and P contents and their stoichiometric ratios in the process of litter decomposition were studied.The results showed that:(1)The contents of C,N and P in all treated leaves and branches decreased in a descending-rising fluctuation during the whole decomposition process.Decompose a year later,three kinds of leaves and branches of N,P content in D2 to deal with the lowest,D2 to deal with the lowest leaf C content,D1 deal with minimum C content,and D1 and D2 leaf C and N content was significantly lower than control(P<0.05),CK was significantly lower than D2 and D1 processing branch C content CK treatment(P<0.05),three branches N content had significant difference(P<0.05).(2)After one year of decomposition,there were significant differences between leaves and branches C︰N treated with two kinds of thinning density and CK treated with control(P<0.05),and there were no significant differences between leaves and branches C︰P and N︰P treated with three kinds of thinning density(P>0.05).(3)There were significant positive correlations between leaf C and leaf N,leaf C︰N,leaf N and leaf P,and extremely significant positive correlations between leaf C and leaf P.Leaf C︰N was negatively correlated with leaf N︰P.There were significant positive correlation between branch C and Branch P,and between branch N and branch N︰P.Branch C︰N and branch N︰P showed significant negative correlation.Branch N and Branch C︰N,branch P and branch C︰P showed extremely significant negative correlation.The results showed that the branch C︰N and branch C︰P were significantly increased after thinning(thinning intensity 23%)at 240d,and the branch C︰N and branch C︰P were significantly decreased at 360d,while the branch C︰N was increased at 360 d.In the whole decomposition process,weak thinning treatment had no significant effect on N︰P.The branches C︰N,C︰P,and N︰P were significantly reduced at 60 d,300 d,and 360 d after thinning(32%).In the whole decomposition process,the intensity thinning had no significant effect on the leaf N︰P.