Abstract: The root system characteristics are important for the spacing decision of plants.The vertical distribution pattern of root biomass,specific root length(SRL),and root length density(RLD) of active roots of 1-to 3-year aged Haloxylon ammodendron(Mey.) Bunge plantations in dry desert steppe was surveyed within a growth season by whole plant excavation method.The results show that the number of roots increased in the lower soil layer along with the increasing age of plants,but the proportion of fine roots deceased.Roots were mainly concentrated in 0~20 cm layer of 1-year aged H.ammodendron and the corresponding biomass accounted for 82.60% of the total root system.Roots were mainly concentrated in 20~60 cm layer of 2-year aged H.ammodendron and the root biomass in 0~40 cm accounted for 73.76% of the total root system.For 3-year aged H.ammodendron,roots were mainly distributed in 40~80 cm layer and root biomass mainly concentrated in upper layer.Fine roots had highest SRL and RLD values and the soil layers with more fine roots had higher SRL and RLD.

Key words: Haloxylon ammodendron(Mey.) Bunge, Root distribution, Specific root length, Root length density

摘要： 采用全株挖掘法对干旱荒漠区梭梭(Haloxylon ammodendron(Mey.)Bunge)人工林进行取样,研究1-3龄梭梭根系生物量、比根长和根长密度的垂直分布格局,为提高造林质量和合理有序地人工接种肉苁蓉提供参考。结果表明:随着树龄增加,土壤层数增加,但细根数占总根比例减少;1龄梭梭的根集中分布在0~20cm土层,根干重占根系总量的82.60%;2龄梭梭根数以20~60cm层中最多,而0~40cm层根重占总根重的73.8%;3龄梭梭根系条数以下层为主,主要集中在40~80cm土层,但生物量多集中于上层;细根的比根长和根长密度最大,则分布细根较多的土层比根长和根长密度值均较大。因此,不同树龄梭梭根系集中区域具有下移趋势,为提高肉苁蓉(Listanche desertiwla Y.C.Ma)的种子萌发和接种机率,人工接种肉苁蓉深度也应下移。

关键词: 梭梭, 根系分布, 比根长, 根长密度