秦岭两种典型人工林不同密度时的枯落物持水功能差异

目的 探究秦岭林区典型森林不同密度时的枯落物持水功能差异,为该区植被建设提供依据。 方法 在秦岭火地塘林区,选取油松林和锐齿栎林3个密度（低、中、高）的样地,利用室内浸水法、熵权法定量分析和综合评价枯落物层持水功能。 结果 ①油松林、锐齿栎林枯落物层厚度分别变化在3.48～5.14 cm、6.54～9.48 cm,枯落物蓄积量均为中密度时最大,分别为9.09、5.61 t·hm−2,其中油松林枯落物蓄积量以半分解层为主（56.5%～60.55%）,锐齿栎林以未分解层为主（63.58%～74.53%）;②油松林枯落物的最大持水量在中密度最高（24.55 t·hm−2）,而锐齿栎林枯落物的最大持水量则在高密度时最大,达到17.8 t·hm−2;油松林和锐齿栎林枯落物吸持水分的主要贡献者分别为半分解层和未分解层;③枯落物的累积持水率在浸水后10 min内迅速增大,且锐齿栎林的增速大于油松林;枯落物吸水速率随浸水时间增加先快速降低后逐渐降低并趋于0;枯落物的持水率（量）、吸水速率与浸水时间分别呈较好的对数和幂函数关系。 结论 油松林半分解层和锐齿栎林未分解层枯落物的持水作用可以互补,其中锐齿栎林密度在725株·hm−2时为最佳。建议营造松栎混交林,并且合理控制密度,以充分发挥其枯落物的水文功能。

Differences in the Water-retention Function of Humus Layer between Two Typical Forests with Different Densities in the Qinling Mountains

Objective The differences in water-retention function of humus layer in typical forests with different densities in the Qinling Mountains were explored to provide basis for the vegetation construction. Methods Three plots with different densities (low, medium, and high) of Pinus tabulaeformis forest and Quercus aliena va.acuteseata forest were selected in Huoditang of Qinling Mountains. The indoor soaking and entropy weight methods were used to quantitatively analyze and comprehensively evaluate the water-retention function of humus layer. Results ①The thickness of humus in Pinus tabulaeformis and Quercus aliena va.acuteseata was 3.48～5.14 cm and 6.54～9.48 cm, respectively. The weight was the largest when the density was mediumwith 9.09 and 5.61 t·hm−2, respectively. The humus of Pinus tabulaeformis forest was mainly semi-decomposed layer (56.5%～60.55%), while that of Quercus aliena va.acuteseata forest was mainly undecomposed layer (63.58%～74.53%); ②The maximum water holding capacity of humus in Pinus tabulaeformis forest was found in medium density (24.55 t·hm−2), while that in Quercus aliena va.acuteseata forest was found in high density, which reached 17.8 t·hm−2 . The semi-decomposed layer of Pinus tabulaeformis forest and the undecomposed layer of Quercus acutissima forest played a major role in the absorption and retention of water by humus in the two forests; ③The accumulated water holding capacity of humus increased rapidly within 10 minutes after soaking, and the water holding growth rate of humus in Quercus aliena va.acuteseata forest was better than that of Pinus tabulaeformis forest. With the increase of soaking time, the water absorption rate of humus first decreased rapidly, then gradually decreased and tended to 0. The water holding rate(capacity), water absorption rate and soaking time of humus showed logarithmic and power function, respectively. Conclusion The water retention function of the semi-decomposed layer in Pinus tabulaeformis and undecomposed layer in Quercus aliena va.acuteseata forest can be complement each other, and the best performance of the Quercus aliena va.acuteseata forest can be reached when the density was 725 trees·hm−2. It is suggested to build a Pinus tabulaeformis Quercus aliena va.acuteseata mixed forest and control the density reasonably, so as to fully contribute to the hydrological function of humus.