盐结皮对艾比湖湿地土壤特性的影响及其自然要素分析

为探讨艾比湖湿地内土壤盐结皮(SSC)与土壤特性的相互作用关系,以及影响SSC厚度的自然要素。采用野外调查与室内试验相结合的方法,在湿地内选取30个具有代表性的样点,并在其周围选取无SSC的样点(30个)作对比,对研究区内有SSC和无SSC覆盖的土壤特性(有机质、容重、质量含水量、总盐、全氮、全磷和p H)进行对比分析,并结合气候要素(风速、气温、湿度和降水量)探讨其对SSC厚度的影响。结果表明:(1) SSC覆盖的土壤总盐平均含量为27.7 g/kg,质量含水量为16.8 g/kg,显著高于无SSC覆盖的土壤总盐(17.8 g/kg)和质量含水量(10.7 g/kg),有SSC覆盖的土壤有机质、全磷和全氮含量分别为6.9、0.88和0.63 g/kg,低于无SSC覆盖的土壤有机质(8.8 g/kg)、全磷(1.05 g/kg)和全氮(0.87 g/kg),有SSC覆盖的土壤碱性更强、容重更大;(2) SSC覆盖下的土壤总盐、容重和p H随深度增加而下降,质量含水量、全磷和全氮随深度增加而增加。SSC厚度与土壤总盐(0.676**)、质量含水量(0.513**)和容重(0.484*)成正相关,与有机质(-0.426*)、p H(-0.402*)、全磷(-0.233)和全氮(-0.303)呈负相关,随深度增加相关性逐渐减弱;(3)主成份分析表明SSC厚度3 cm时,土壤总盐、质量含水量和风速对其影响最大,权重分别为0.42、0.25和0.17。总之,SSC可以提高土壤保水性,增加土壤容重,但不利于养分的积累,会使土壤碱化、盐化更强烈。SSC的厚度受土壤总盐、质量含水量和风速的影响较大。

The Effects of Salt Crust on Soil Property and the Influencing Natural Factors in the Aibi Lake Wetland

In order to explore the interaction between soil salt crust(SSC) and soil property in Aibi Lake wetland and to disclose the natural factors that influence the thickness of salt crust, the method of field investigation combined with laboratory test was adopted. Totally 60 representative sample points were selected, with 30 in the wetland and 30 without SSC, and the spatial and vertical variations of soil properties (volume weight, OM, water content, salt, total-P, total-N and pH) with and without salt crust in the study area were analyzed, and the influence of wind speed, temperature, humidity and precipitation on the salt crust thickness was discussed. The results showed that:(1) The average of total salt and water content in the salt crust-covered soil were 27.7 g/kg and 6.8 g/kg, respectively, these were significantly higher than that in the soil without SSC cover(17.8 g/kg for total salt and 10.7 g/kg for water content).The contents of organic matter, total phosphorus, and total nitrogen in soil covered by SSC were 6.9, 0.88, and 0.63 g/kg, respectively, these values were significantly lower than OM(8.8 g/kg), total-P (1.05 g/kg), and Total-N(0.87 g/kg) in soil without SSC cover. Soil with SSC were more alkaline and had higher bulk density.(2) The total salt content, density, and pH of soil under the salt-crust cover decreased with the increase of depth, while the water content, total phosphorus, and total nitrogen increased with the increase of depth. Salt crust thickness was positively correlated with total salt (0.676^**), water content (0.513^**), and bulk density (0.484^*), while was negatively correlated with organic matter (-0.426^*), pH(-0.402^*), total phosphorus (-0.233), and total nitrogen (-0.303). The correlation decreased gradually with the increase of depth.(3) Principal component analysis showed that when the salt crust thickness was >3 cm, the total salt, moisture and wind speed had the largest contribution to the salt crust thickness, with the weight of 0.42, 0.25 and 0.17, respectively. In a word, salt crust can improve the soil water retention and increase the soil bulk density, but it is not conducive to the accumulation of nutrients and will make soil alkalization and salinization more intense. To sum up, the formation of salt crust was mainly affected by the total salt, moisture of soil and wind speed.