共和盆地中间锦鸡儿人工林根系的分布特征

采用剖面法对青海共和盆地中间锦鸡儿（Caragana intermedia）人工林的根系进行调查,分析5 a、9 a和25 a根系的生物量、比根长和根长密度的垂直分布格局,同时测定土壤含水量的垂直变化。结果表明:①不同林龄中间锦鸡儿人工林的吸收根（d≤1 mm）和输导根（d>1 mm）的主要分布范围不同。5 a、9 a和25 a吸收根主要分布土层分别是10～30、10～50 cm和10～60 cm,输导根主要分布土层分别是10～50、10～60 cm和10～90 cm。②随着林龄的增加,根系的吸收根、输导根的总生物量、总比根长和总根长密度均显著增加（P<0.05）;各林龄根系中的吸收根比输导根具有更高的比根长和根长密度（P<0.05）。因此,吸收水分和养分的能力随着林龄增加而增大。③中间锦鸡儿人工林根系,尤其是吸收根的分布影响土壤水分变化,吸收根集中分布土层的土壤含水量显著降低。

Root System Distribution of Caragana intermedia Plantation in Gonghe Basin,Qinghai Province

The vertical distribution patterns of root biomass, specific root length (SRL) and root length density (RLD) of 5-year, 9-year and 25-year Caragana intermedia plantations in Gonghe Basin of Qinghai Province was investigated with profile method, and soil water content in the soil profile was also measured. Results show that: (1) The absorptive roots (diameter≤1 mm) and conductive roots (diameter >1 mm) of C. intermedia in the three plantations are distributed in different soil layers. The absorptive roots of 5-year, 9-year and 25-year Caragana intermedia plantations are mainly distributed in 10-30 cm, 10-50 cm and 10-60 cm soil layers, respectively, whereas the conductive roots mainly appear in 10-50 cm, 10-60 cm and 10-90 cm soil layer, respectively. (2) The total biomass, SRL and RLD of absorptive roots and conductive roots significantly increase with increase of plantation age (P<0.05). The SRL and RLD of absorptive roots are significantly higher than that of conductive roots (P<0.05). So, the absorbability of soil water and nutrition of C. intermedia increases with increase of plantation age. (3) Soil water content is affected by root system distribution, especially absorptive roots distribution. Soil water content in the concentrated areas of absorptive roots distribution is very low.