川西高原季节性雪被覆盖对窄叶鲜卑花凋落物分解和养分动态的影响

Effects of snow cover on the decomposition and nutrient dynamics of Sibiraea angustata leaf litter in western Sichuan plateau,Southwest China

2010年1—5月在川西高原采用人工雪厚度梯度试验(0、30和100cm),应用网袋分解法对窄叶鲜卑花叶片凋落物进行分解试验,测定了凋落物的分解速率及其养分动态.结果表明:在无雪被覆盖的样地上分解5个月后的凋落物质量损失率为29.9%,而中雪和深雪样地的凋落物质量损失率分别为33.8%和35.2%.分解过程中,凋落物氮存在一定的富集现象,磷处于波动的富集状态,碳质量分数和碳氮比均呈现前期急剧下降后期逐渐上升的趋势.雪被覆盖显著增加了凋落物的质量损失率和氮含量,而对碳和磷含量无显著影响.在川西高原地区,30cm以上的持续雪被覆盖能够改变凋落物的分解过程,从而可能对土壤营养物质转化和植物群落构建产生实质性的影响.

Soil-borne bag method was adopted to study the decomposition and nutrient dynamics of Sibiraea angustata leaf litter under different depths （0, 30 and 100 era） of snow cover in western Sichuan plateau in January-May, 2010. In snow-free plot, the mass loss rate of the litter over the five months was 29.9% ; in the plots with 30 and 100 cm snow cover, the litter mass loss rate was 33.8% and 35.2%, respectively. During the decomposition, definite N enrichment in the litter was observed, while the P enrichment fluctuated. The C content and C/N ratio of the litter de- creased sharply at the early stage of decomposition, but increased gradually after then. Snow cover greatly contributed to the rapid decomposition of litter and the N enrichment in the litter, but had little effects on the litter C and P contents. In western Sichuan plateau, durable snow cover with a depth of 〉30 cm could alter the litter decomposition pattern, and substantially affect the soil nutri- ent turnover and plant community composition. Key words： western Sichuan plateau; snow cover; Sibiraea angustata ; litter decomposition; nutri- ent.