Distribution of soil algae in salinized irrigation land in the arid region of Central Asia

Abstract

Distribution patterns of soil algae were investigated in a 14-year-old farm and its surroundings in the salinized irrigation land of Central Asia. Using a culture dilution method, the densities of five groups of soil algae, green colony group (composed of chlorophytes together with xanthophytes), Chroococcales, Oscillatoriales, Nostocales in the orders of blue-green algae, and diatoms, were estimated. The differences in the distribution patterns among the green colony group, the Oscillatoriales and the N ostocales attributed to soil salinity and soil moisture. As the green colony group was more sensitive to salinity than the blue-green algae, the density decreased at a relatively higher salinization level (EC > ca. 8 dS m-1). The blue-green algae, especially the Nostocales, were not affected by such degree of salinization. However, the nostocalean blue-green algae also could not occur in the further developing safinized part where salt crusts were observed. These results show that few soil algae occurring at the study site were able to adapt to the land with high salinity induced artificially. Around the sand dune where salt accumulation had never occurred, several species belong to the green colony group were dominant and few blue-green algae were observed. This observation suggests that these species had developed some strategies to tolerate water stress because this area was subjected to extremely dry conditions.