干旱区油蒿生物量凋落分解与土壤呼吸

 生物量的凋落分解与土壤呼吸影响流沙基质中CaCO3的淋溶和淀积。为研究腾格里沙漠油蒿群落中土壤CaCO3的形成,对油蒿当年生物量的凋落分解与土壤呼吸进行了探讨。结果表明：在腾格里沙漠,固定沙地上油蒿当年生物量（41.51±1.76）g·m-2]显著高于半固定沙地（32.31±0.92)g·m-2],固定沙地上油蒿叶量籽量和（32.89±1.34)g·m-2]也显著高于半固定沙地（19.32±0.64)g·m-2];但不同立地油蒿叶量和籽量的分解速率均大于0.6692 g·g-1·a-1,且油蒿的凋落物需要4.48 a才能达到分解最大值。另一方面,油蒿半固定沙地、油蒿固定沙地和油蒿+冷蒿固定沙地的土壤呼吸速率均存在显著差异;统计分析表明,油蒿+冷蒿固定沙地土壤呼吸速率最低（7.37±1.07)mg CO2·m-2·h-1]可能与油蒿+冷蒿固定沙地土壤中较高的pH值和较低的土壤呼吸脱氢酶活性有关。可见,干旱区油蒿群落越到固定阶段,凋落量越大,释放的Ca2＋越多,土壤呼吸速率越低,土壤中的pH值越高,而这越有利于土壤中CaCO3的形成。

Litterfall and Decomposition of Biomass and Soil Respiration of Artemisia Ordosica Communities in Arid Region

Both the litterfall and decomposition of aboveground biomass and the soil respiration affect the eluviations and deposition of calcium carbonate in aeolian sand substrates. To study the formation of calcium carbonate in soil of Artemisia ordosica community in Tengger Desert, this paper focused on the litterfall and decomposition of annual biomass and the soil respiration in communities of A. ordosica. The results indicated that the annual biomass in fixed sand dune (41.51±1.76)g\5m-2] was significantly higher than that in semi-fixed sand dune (19.32±0.64)g·m-2], and the annual litterfall (32.89±1.34)g·m-2] was also significantly higher than that in semi-fixed sandy land (19.32±0.64)g\5m-2] . The decomposition rate of the litterfall of A. ordosica all exceeded 0.6692 g·g-1·a-1 in different sites, and those litterfall might need 4.48 years to reach the peak value of decomposition rate, theoretically. Statistical analysis suggested that there were significant differences among soil respiration rates on A. ordosica semi-fixed sand dune, A. ordosica fixed sand dune, and A. ordosica+ A. frigida fixed sand dune, and the lowest soil respiration rate in A. ordosica + A. frigida fixed sand dune (7.37±1.07)mg\5m-2\5h-1] might be related to high pH value of soil solution and low activity of soil dehydrogenase. The higher fixed degree of the A. ordosica sand dune implies the more litterfall, the more released Ca2+; the lower soil respiration rate, the higher soil pH value, all of them will promote the formation of calcium carbonate in soil.