论文部分内容阅读
采用原状土芯(intact core)法,探讨了四川洪雅柳江退耕还林模式:光皮桦(Betula luminif-era)与扁穗牛鞭草(Hemarthria compressa)复合模式(HN)、光皮桦人工林(H)、扁穗牛鞭草牧草地(NC)、柳杉(Cryptameria fortunei)人工林(LS)细根、草根分解速率以及其与细根、草根分解密切相关的土壤微生物功能群变化,结果表明:①细根、草根分解速率符合Olson单指数分解模型,年分解常数(k)分别为1.06、0.93、1.32、0.86/年,分解1年后干重损失率分别为65.49%、60.55%、73.32%、57.51%;②在一年的分解期间的各个阶段HN模式的好气固氮细菌、氨化细菌、硝化细菌、纤维素分解菌数量都显著大于其他3种模式(p<0.01);③4种模式固氮细菌与氨化细菌数量呈显著正相关关系,与C/N呈显著负相关关系,氨化细菌数量与硝化细菌数量呈显著正相关,HN、LS模式固氮细菌数量与细根、草根N相对含量呈显著正相关关系(p<0.05),表明细根、草根的分解受到土壤微生物生理类群相互作用的影响,自生固氮在林草复合模式与柳杉人工林生态系统的自肥作用中扮演着重要角色。
Using the intact core method, this paper discussed the model of returning land for farming to forestry in Hongya Liujiang River, Sichuan Province. The composite model (HN) of Betula luminif-era and Hemarthria compressa, (H), NC, Cryptocarya fortunei plantation (LS) fine roots, the rate of root decomposition, and the changes of soil microbial functional groups closely related to fine root and grass root decomposition, The results showed that: (1) The fine roots and grass roots decomposition rates were in accordance with the Olson single exponential decomposition model. The annual decomposition constants (k) were 1.06, 0.93, 1.32 and 0.86 per year respectively. The dry weight loss rates were 65.49% and 60.55% , 73.32% and 57.51%, respectively. ②The numbers of aerobic, nitrogen-fixing bacteria, ammonifying bacteria, nitrifying bacteria and cellulolytic bacteria in HN model were significantly greater than those in the other three modes (p <0.01) at all stages of one year’s decomposition. There was a significant positive correlation between the number of nitrogen-fixing bacteria and the number of ammonifying bacteria and the negative correlation with C / N. The number of ammonifying bacteria was positively correlated with the number of nitrobacteria. The number of nitrogen-fixing bacteria N relative content was significantly positive correlation (p <0.05), Details roots, roots decomposition of soil microbial populations affected by the interaction of nitrogen fixation plays an important role in enrich Silvopastoral role model and ecosystem cedar plantation.