外加氮源及与林下植物叶混合对杉木林针叶分解和养分释放的影响  

Effects of Nitrogen Addition and Mixture with Understorey Plant Leaves on Decompositions and Nitrogen Releases of Chinese Fir Needle Litter

作　　者：项文化[1] 闫文德[1] 田大伦[1] 雷丕锋[1] 方晰[1] 

机构地区：[1]中南林学院生态研究室,长沙410004

出　　处：《林业科学》2005年第6期1-6,共6页Scientia Silvae Sinicae

基　　金：国家重点野外台站资助项目(2000-076);国家林业局重点科研项目(2001-07);教育部留学回国人员科研启动基金项目(2004-527);湖南省高等学校青年骨干教师项目资助。

摘　　要：通过外加氮源或将杉木针叶与林下植物叶混合来改变杉木林凋落物中针叶的养分状况,与杉木林针叶凋落物分解进行比较,分析针叶养分状况及其对杉木林凋落物分解速率和养分释放的影响.结果表明:将杉木针叶与林下植物叶混合和外加氮源均对凋落物分解有不同程度的促进作用.经过153 d的分解后,未经处理的杉木针叶干质量损失率为20.49%,与林下植物叶混合的凋落物干质量损失率为43.67%,其促进作用最大;外加4 gNaNO3的促进作用次之,凋落物干质量损失率为42.07%;外加2 g NaNO3的凋落物干质量损失率为29.13%.对分解过程中各试验方案的凋落物干质量保留率进行方差分析,在开始的62 d内,与林下植被叶混合的杉木针叶凋落物分解速率和其他3种处理之间的差异显著,62 d后未经处理的杉木针叶与加2 g NaNO3的凋落物的分解速率没有显著差异,它们与加4 g NaNO3或林下植物叶的凋落物的分解速率差异显著.凋落物分解速率与凋落物初始C:N比值存在显著的线性关系.外加N源和与林下植物叶混合后,凋落物N的含量增加0.6～1.6倍,C:N比值下降0.4～0.6倍,凋落物底物质量提高,分解速率增大.分解过程中,C质量不断下降,损失24.7%～47.4%,杉木针叶中N出现富集作用,外加N源和与林下植物叶混合的凋落物N释放一定数量后保持稳定的状态.可见,外加适量N源和与林下植物叶混合能提高凋落物底物质量,促进凋落物分解和养分的释放,对维持杉木林的土壤肥力有着重要作用.Four treatments of Chinese Fir needle litter, Chinese Fir needle litter with addition of 2 g and 4 g NaNO3 respestively, and Chinese Fir needle litter mixed with leaves from understorey plants were designed to investigate the effects of nutrient Status on the decomposition rates and nutrient releases of Chinese Fir needle litter using the litter bag technique. The results showed that both adding NO3^--N and mixing with leaves from understorey plants to some extent accelerated the decomposition rate of Chinese Fir needle. The dry mass loss percentage, decomposition rate and half-life time of Chinese Fir needle were 20.49%, 0.001 6 per day and 1.2 a, respectively. Chinese Fir needle litter mixed with leaves from understorey plants had the highest decomposition rate with dry mass loss percentage of 43.67 %, decomposition rate of 0.004 3 per day and half life time of 0.44 a. In the whole decomposition processes, there was a significant difference of decomposition rate between Chinese Fir needle litter mixed with leaves from understorey plants and Chinese Fir needle litter. The amount of NaNO3 addition also affected the decomposition rate. Addition of 4 g NaNO3 had higher decomposition rate with dry mass loss percentage of 42.07%, decomposition rate of 0.003 7 per day and half life time of 0.51 a than addition of 2 g NaNO3 with dry mass loss percentage of 29.13 %, decomposition rate of 0.002 2 per day and half life time of 0. 86 a. The decomposition rate accelerations could be attributed to improvement in litter quality, in particular N content increase and C：N ratio decline, because the relationship between the initial litter C ： N ratio and the proportion of dry mass remaining was significant. The N content in litter after NO3^- -N addition and shrub leaves mixing had been increased as many 0.6 -＇1.6 times as that in Chinese Fir needle litter. The reduction of C ： N ratios was 0.4 - 0.6 times. Nitrogen immobilization was observed in the decomposition processes of Chinese Fir needle while N mineralization fol

关 键 词：杉木林 针叶凋落物 分解速率 林下植物 N含量 C:N值 

分 类 号：S791.27[农业科学—林木遗传育种]