施肥和增雨雪对矮嵩草草甸4种典型植物凋落物分解的影响

Effects of Fertilizer and Water Additions on the Litter Decomposition of Four Typical Plants in Kobresia humilis Meadow

设9个试验处理(夏季增雨、冬季增雪、施N肥、施N肥与夏季增雨交互作用、施N肥与冬季增雪交互作用、施P肥、施P肥与夏季增雨交互作用、施P肥与冬季增雪交互作用和对照)研究增施氮磷肥及水分对海北站矮嵩草(Kobresia humilis)草甸中垂穗披碱草(Elymus nutans)、矮嵩草、甘肃棘豆(Oxytropis kansuensis)与麻花艽(Gentiana straminea)4种典型植物地上部分凋落物分解速率的影响。结果表明:凋落物分解速率为甘肃棘豆>麻花艽>矮嵩草>垂穗披碱草,甘肃棘豆地上部分分解最快,垂穗披碱草的分解最慢,不同植物功能类群间差异显著。4种植物地上部分分解最快的时间都在降水充足的夏季。分解第185 d和262 d时,垂穗披碱草的质量残留率均极显著高于其他3种(P<0.01),麻花艽质量残留率极显著低于矮嵩草(P<0.01);分解362 d时,甘肃棘豆的分解速率显著高于垂穗披碱草和矮嵩草,但棘豆与麻花艽间差异并不显著,这与不同牧草的适口性、氮磷含量等属性有关。在N处理下,棘豆地上部分分解最快,分解其质量的95%所需时间为649.5 d,比对照缩短286.7 d。在没有增雨雪的基础上增施氮磷肥则对矮嵩草地上部分的分解起抑制作用,但影响不显著,水肥效应加以耦合会加速凋落物的分解。

The effects of fertilizer and water addition on the aboveground litter decomposition of four typical plants in the alpine meadow of Haibei station in Qinghai province. Nine treatments were designed. Results showed that the litter decomposition rates of tested plants were ordered as O. kansuensis〉G, straminea〉 K. humilis〉E, nutans There was significant difference between plant functional groups. The litters in summer decomposed the fastest. The quality residual rates of E. nutans after 185 days and 262 days de- composition were significantly higher than that of other tested species （P〈0. 01）. The quality residual rate of G. straminea was significantly lower than that of K. humilis （P〈0. 01）, whereas the decomposi- tion rate of O. kansuensis was significantly higher than that of E. nutans and K. humilis after 362 days de- composition. The difference between O. kansuensis and G. straminea was not significant that was related to the palatability, the nitrogen and phosphorus contents of tested grasses. The littler of O. kansuensis de- composed the fastest under the N treatment. It took 649.5 days to decompose the 95% quality of O. kan- suensis litter, and that was 286.7 days shorter than CK treatment. The aboveground litter decomposition of K. humilis was inhibited after applied fertilizer without water. However, there was no significant difference among treatments. The interaction between water and fertilizer would accelerate the litterdecomposition.