模拟增温增水对克氏针茅草原主要物种及群落凋落物分解的影响

摘要

In this study, open top chambers (OTCs) were used to simulate warming. Three treatments, warming (W), precipitation enhancement(P), warming combine with precipitation enhancement(WP) were set in comparison with natural state to investigate the litter decomposition rate of main species inStipa krylovii steppe includingStipa krylovii,Cleistogenes squarrosa,Artemisia frigida and the community littlers. The results showed that: (1) after one year of decomposition, the fraction of mass remaining of all litter types in warming treatment were higher than those of control, so warming slowed down the decomposition rate of the litters. The interactive effect of warming and precipitation enhancement on the mass remaining fraction of all litter types was consistent with that of warming tratment, but the influence of warming on the the litter decomposition was greater. However, enhanced precipitation had no significant influence on the litter mass remaining faction. (2)Warming did not influence the litter decomposition process of different litter types, while enhanced precipitation significantly accelerated the decomposition processes ofCleistogenes squarrosa. Warming combining with enhanced precipitation influenced decomposition ofArtemisia frigida strongly. (3)Analysis of variance showed that the effects of warming and enhanced precipitation on litter decomposition were mainly related to the litter types and the duration of decompostion. (4) Olso negative index model was used to simulate the litter mass loss processs, which showed that under warming treatment the k values (characterization of decomposition rate) of all the litter types except forArtemisia frigida were lower than the control, while in enhanced precipitation treatment the k values were higher for Stipa krylovii andCleistogenes squarrosa but lower forArtemisia frigida and coummity litters compared to the control. The interactive effect of warming and enhanced precipitation on k values of all the litter types was consistent with that of warming, but the k values under warming and precipitation enhancement treatment were higer than those of warming. Our results suggested that the litter decomposition rate ofStipa krylovii steppe in Inner Mongolia would tend to slow down under future climate change. Warming and precipitation variation due to climate change have important influence on litter decomposition,but few researches focused on the interactive effect of warming and precipitation variation on the litter decomposition.%应用开顶式生长室（OTC, Open Top Chamber）模拟增温，以自然状态为对照，设增温(W)、增水（P）和增温+增水（WP）3个处理，对克氏针茅草原主要物种克氏针茅(Stipa krylovii)、糙隐子草(Cleistogenes squarrosa)、冷蒿（Artemisia frigida）以及群落凋落物的分解速率进行试验研究。结果表明：(1)经过1a的分解，W 处理下各物种凋落物质量残余率高于 CK，即增温减缓了凋落物的分解；WP 处理对凋落物质量残余率的影响与W处理一致，但其增温的影响程度更大；P处理下凋落物残余率与CK无显著差异。(2)增温对不同种类凋落物分解进程无显著影响；而增水明显加快了糙隐子草的分解进程；增温+增水对冷蒿的分解进程影响较大，但最终各物种凋落物残余率差异不显著。(3)对残余率变化动态的方差分析表明,增温增水对凋落物分解的影响主要与凋落物种类以及分解时间的长短有关。(4)采用 Olso 负指数模型模拟凋落物质量损失变化过程，增温条件下，除冷蒿外，其它各种凋落物的 k 值（表征分解速率）均低于 CK；增水条件下，克氏针茅和糙隐子草的k值低于CK，而冷蒿和群落凋落物的k值高于CK；增温+增水条件下，不同种类凋落物k值的变化与W处理一致，但整体上WP处理下凋落物的k值高于W处理。根据研究结果可以推断出，未来气候变化下内蒙古克氏针茅草原凋落物的分解将趋于减缓。