塔里木盆地柽柳灌丛沙堆盐分分布特点研究

为明确处于稳定阶段柽柳灌丛沙堆内土壤盐分的分布规律及其对环境可能产生的影响,以塔里木盆地北缘洪积冲积扇末端为研究区,分析了灌丛沙堆内与堆间地盐分的分布特征及其与柽柳灌丛凋落物年产量的关系.研究结果表明,柽柳灌丛沙堆表层土壤(0-30 cm)盐分明显低于堆间地表层土壤盐分,相关分析表明,柽柳灌丛凋落物产量的增加是抑制盐分表聚的一个重要因素.而沙堆深层土壤(30-120 cm)盐分则明显高于堆间地相同深度的土壤盐分,呈明显的富集状态,即形成了明显的“盐岛”.盐岛内主要富集K+,Na+,C1和HCO3-这4种离子,其余离子(SO24-,Ca2+,Mg2+)则呈均匀分布或随机分布.以上结果表明,柽柳灌丛沙堆是土壤盐分局部汇集的小型盐分库,它的演变趋势会对干旱区绿洲生态系统的稳定性产生潜在的影响.

Distribution Pattern of Soil Salinity in Tamarix Nebkhas in Tarim Basin

The relationship between soil salinity in the top soil of nebkhas and annual litter-fall production of tamarisk shrub was analyzed to clarify the distribution of soil salinity patterns in and outside Tamarix nebkhas and their effects on oasis ecosystem.Results indicated that soil salinity in nebkhas surface soil(0-30cm)was lower than in internebkhas.Annual litter production was found to be an important factor reducing soil salinity in surface soil beneath the canopy according to correlation analysis.In contrast,soil salinity enrichment was observed in deeper soil layer(30-120cm)in the Tamarixnebkhas compared to internebkhas,which indicated the formation of salinity islands in nebkhas.K⁺,Na⁺,Cl^-and HCO₃ were the four important ions enriched in resource islands.The other three ions(SO₄^2-,Ca²⁺and Mg²⁺)were distributed evenly or randomly in deeper soil.These results suggested that the Tamarix nebkhas gathered soil salinity from internebkha spaces.The fate of Tamarixnebkhas will affect the stability of oasis ecosystem in the arid zone.