退耕地青海云杉人工林土壤抗冲性试验研究

Experiment on Soil Anti-scourability of Artificial Picea crassifolia Forest in Rehabilitation Lands

青海云杉为青海省大通县的顶极植物群落树种,是当地退耕还林的主要树种。通过研究退耕地青海云杉人工林的土壤抗冲性,对于科学指导当地生产实践、制定退耕还林方案等十分必要。三因素三水平的正交试验结果表明,土层、坡度、流量对抗冲性的影响依次增强,以流量对抗冲性的影响最大。<1mm根数是影响土壤抗冲性的主要生物因素,<1mm根数越多,土壤抗冲性越强。青海云杉人工林根系为表层聚积、下层骤减的分布类型。表土层(0～20cm)为根系密集分布层,<1mm根数占98.88%,根长占91.37%,该层根系对土壤颗粒的网络粘结作用最好,抗冲性最强,其平均值达到0.830min/g,为中层(0.201min/g)抗冲性的4倍。退耕还林还草工作中,应重视对在表土层中密集分布须根类型植物的应用。

Picea crassifolia is a species of climax community in Datong county, Qinghai province, and is used as the main afforestaion species in the project of converting from cropland into forest lands and grasslands. It is very important to study the soil anti-scourability of Picea crassifolia in the rehabilitation lands for directing practice and making layout of the conversion from croplands into forest lands and grasslands. The orthogonality experiment with three factors and three levels shows that runoff is the first important factor which influences the anti-scourability greatly, then comes slope and soil layers. The number of less than 1 mm roots are the main biological factor which seems to have a same trend with anti-scourability. The more the numer of less than 1 mm roots, the stronger the anti-scourability. The roots of Picea crassifolia distribute more in the top soil layer and sharp less in the under soil layers. The number of less than 1 mm in the top soil layer (0～20 cm) , also the roots accumulating layer, accounts for 98.88% of the total layer, and length of roots accounts for 91.37%. The roots in the top soil layer aggregate and cling soil granules well and thus the anti-scourability of the top soil layer is the largest with a average value of 0.830 min/g which is fourfold as big as that of the medium soil layer. Those plants with a lot of fiber roots at the top soil layer must be paid more attention in the engineering of conversion from croplands into forest lands and grasslands.