油蒿演替系列土壤基质的演变

土壤基质变化影响干旱、半干旱区植物群落的演替.对干旱区油蒿群落演替系列土壤基质变化的分析表明,随油蒿群落的演替进展,土壤各层中CaCO3含量显著增加,有机质和土壤全N含量也明显增加,相应各层细菌数量显著增加,油蒿半固定沙地和固定沙地土壤脱氢酶活性显著增强.这些变化促进了油蒿枯枝落叶的分解,加速了Ca2 的释放,促进了土壤呼吸,促进了土壤中CO2的释放,进而促进了油蒿群落土壤中CaCO3的淋溶和淀积.进一步分析得知,油蒿须根是土壤CaCO3形成的重要来源.钙积层的形成使得较油蒿根系更浅的冷蒿植物得以侵入、定居,而油蒿则逐渐退出.因此,土壤基质变化尤其是土壤钙积层的形成是油蒿群落演替的根本原因.

Changes of Soil Substrates in Artemisia Ordosica Succession Series

Soil substrates changing affects succession of plant community in arid and semiarid areas. This paper studied the changes of soil matrix of Artemisia ordosica succession series in semi-arid area. The results indicated that, with the advancing of A. ordosica succession, there existed a significant increase in content of calcium carbonate and number of bacteria and a remarkable increase in content of organic matter and total nitrogen in each soil layer. Meanwhile, the activity of soil dehydrogenase increased significantly in semi-fixed and fixed sandy land of A. ordosica community. Those changes accelerated decomposition of A. ordosica litter and soil transpiration, promoted the release of calcium ion and carbon dioxide, thus enhanced the eluviation and precipitation of calcium carbonate in soil of A. ordosica community. The further analysis suggested that fibrous roots of A. ordosica are much more important during the formation of calcium carbonate. The presence of calcic horizon availed the invasion and residence of A. frigida which is a relatively shallow-rooted plant. In conclusion, the ultimate cause for the succession of A. ordosica community mainly contributes to the changes of soil substrate, especially the formation of calcium carbonate.