不同月份采集的贝加尔针茅地上部的分解特征及影响因素

Decomposition and its affecting factors of Stipa baicalensis shoot tissues collected at different months

利用植物生长过程中植物组织内养分元素化学性质的季节性变化特点,在2009年生长季的不同月份(5—9月)采集了呼伦贝尔地区贝加尔针茅地上部(茎和叶),作为分解底物,采用分解袋法,研究其分解特点及其影响因素。结果表明:不同月份采集的贝加尔针茅分解底物之间的分解速度存在明显差异,依采集月份逐渐递减,5月>6月>7月>8月>9月;分解底物初始N、P、Zn、K、Mg和Mn含量与分解速度均呈显著正相关,而碳含量和C∶N与分解速度呈显著负相关,初始钙含量、N∶P与分解速度无显著相关性;土壤微生物生物量N与分解底物的残余质量(%)相关性明显;另外,土壤微生物生物量N与凋落物C、N含量也具有明显的相关性;分解底物质量损失与土壤水分含量显著正相关,而与土壤温度的相关性较弱,说明降水变化通过调节土壤湿度来影响凋落物分解。

The nutrient contents in plant tissues have a seasonal variation during the process of plant growth. Aiming at this feature, the shoot tisses （induding stems and leaves） of Stipa baicalensis were collected in growth season （from May to September, 2009）, and their decomposition characteristics and related affecting factors were studied by using litterbags. The shoot tissues collected in different months had obvious difference in their decomposition rates, being decreased in the order of May June July August September. The decomposition rates of the substrates were significantly positively correlated with their initial nitrogen, phosphorus, zinc, potassium, magnesium, and manganese contents, significantly negatively correlated with their initial carbon content and C∶N, but less correlated with their initial calcium content and N∶P. There was an obvious correlation between the soil microbial biomass nitrogen and the remaining mass of the substrates. In addition, the soil microbial biomass nitrogen had obvious correlations with the substrate carbon and nitrogen contents. The mass loss of the substrates had significant positive correlation with soil moisture content but weak correlation with soil temperature, suggesting that precipitation change could affect litter decomposition via affecting soil moisture content.