不同生境下盐生灌木盐岛效应的变化及生态学意义

摘要

为探明生境与植物种类对盐岛效应的影响,选取了分布于塔里木盆地北缘盐化草甸生境和灌丛生境的3种盐生灌木,即多枝柽柳(Tamarix ramosissima)、盐穗木(Halostachys caspica)、盐节木(Halocnemum strobilaceum),分析了植丛下与植丛间土壤的pH、总盐和8种盐分离子含量的变化.研究结果表明在盐化草甸生境,只有盐节木植丛下的土壤盐分呈明显的富集状态,即形成了盐岛；而在灌丛生境,3种盐生植物均具有明显的盐岛效应,且盐岛效应以盐节木最高,多枝柽柳最低.数据分析进一步表明盐岛效应的强弱受植物种类和所处生境的影响:即分布于高盐环境的盐生植物和耐盐能力强的植物盐岛效应更为明显.而生境变化和植物种类的不同,对盐岛内盐分离子的富集也有不同的影响.盐岛效应的增强有加速草甸向盐生灌木为主的荒漠退化的趋势.%Soil pH, total soil salt and eight main salt ions ( K+ , Na+ , Ca + , Mg , Cl , S04 , C03 and HCO3~ ) in soils under and in-between groves of Tamarix romasissima, Halostachys caspica, Halocnemum strobilaceum in two habitats, I. E. Saline meadow and shrubland, were analyzed in order to explore effects of habitat and shrub species on salt island effect of halophytic shrubs in north Tarim Basin. Results show that in the saline meadow only under the grove of Halocnemum strobilaceum in the saline meadow, significant salt enrichment was observed in the soil, forming a salt island, while in the shrubland salt island effect was found in soils under all the three halophytic shrubs. That under Halocnemum strobilaceum was the most significant whereas under tamarisk the least. Data analysis further suggested that the salt island effect varied in strength with the halophytic shrub species and the habitat they grew in, that is to say, the salt island effect of halophytes and plants high in salt tolerance in salt-rich habitats is more obvious. And changes in habitat or plant species also influence to a varying extent enrichment of salt ions in the salt island. Intensified salt island effect accelerates degradation of saline meadow into halophyte-dominated desert in north Tarim Basin, Xinjiang.