秦岭华山松林间伐强度对其水源涵养功能的影响

在秦岭旬阳坝林区选择代表性的华山松样地，设置5%、10%、15%、20%共4个间伐强度和未间伐对照（0%）5个处理，对比分析不同间伐强度对华山松林各生态层水源涵养功能的影响，并用坐标综合法进行综合评价。结果表明:间伐后第3年，间伐5%、10%、15%和20%样地的林冠截留率分别低于对照样地 4.41%、6.59%、12.46%和15.01%，干流率分别高于对照样地9.34%、11.67%、16.34%和21.01%；间伐样地枯落物储量和最大持水量均略低于对照样地，随间伐强度的增加，二者分别下降1.20%、9.24%、12.70%、6.49%和3.44%、9.95%、8.99%、5.49%；与对照样地相比，随间伐强度的增大，间伐样地土壤容重分别减少0.78%、2.43%、7.74%、10.43%，土壤最大持水量和土壤稳渗率分别增加0.63%、1.13%、2.32%、3.25%和2.66%、7.10%、10.66%、12.61%。间伐导致林冠层和枯落物层水源涵养功能下降，但影响均较小（p>0.05），间伐增强土壤水源涵养功能，其中以间伐20%最为明显（p<0.05）；总体上，间伐有利于提高水源涵养功能，其中以间伐20%最优，15%次之。

Effect of Thinning Intensity on Water Conservation Capacity of Pinus armandii Forest in Qinling Mountains

Typical Pinus armandii plots with thinning intensities of 5%,10%,15%,20% and 0% (control) were selected in Xunyangba forest region of Qinling Mountains to examine the effect of thinning intensity on water conservation capacity by using comparative analysis method.The results were evaluated by the comprehensive coordinate method.It was found that three years after the treatments,the canopy interception percentages of the forests with four levels of thinning intensities (5% ,10%,15% and 20%) decreased by 4.41%,6.59%,12.46% and 15.01% compared with the control (0% thinning intensity),and the stem flow percentage increased by 9.34%,11.67%,16.34% and 21.01%,respectively.The litter amount decreased by 1.20%,9.24%,12.70%,and 6.49%,respectively,and water-holding capacity decreased by 3.44%,9.95%,8.99%,5.49%,respectively.Compared with the control plot,the soil bulk density decreased by 0.78%,2.43%,7.74%,10.43% respectively and soil saturated water content increased by 0.63%,1.13%,2.32%,and 3.25%,respectively,and stable infiltration increased by 2.66%,7.10%,10.66%,and 12.61%,respectively.Thinning measure could reduce water conservation capacity of the canopy and litter layer,but the impacts were not significant (p>0.05).Thinning measure could increase water conservation capacity of the soil layer,and 20% thinning intensity was more obvious (p<0.05).On the whole,thinning measure would be beneficial to improving water conservation capacity of Pinus armandii forest and 20% thinning intensity had the highest water conservation capacity,followed by 15% thinning intensity.