图1 茭草凋落物分解模拟增温与生境差异实验。A, 三种生境包括大气界面、水界面以及土界面。其中, 大气界面中的凋落物袋悬于PVC管上方距离地面1.2 m处; 水界面中的凋落物袋中放入乒乓球使凋落物袋始终悬浮于水中; 土界面中的凋落物袋通过PVC管将其固定在5.0 cm掩埋深度的底泥中。B, 开顶式生长室(OTC)的设计及运行。其中, 对照组无OTC装置, OTC增温组以直径为2.4 m的底座以及直径为2.0 m的开口所设计建造的阳光板为材料, 实现大气增温模拟。2014年12月至2015年12月全年实时采集(1次·h-1)对照组与OTC增温组中的气温数据, 实现1.5-2.0 ℃温度增幅。C, 研究对象为湿地挺水植物茭草的叶凋落物, 包括增温实验和生境差异实验(其中增温实验对照组和生境差异实验中大气界面的样品相同)。

Fig. 1 Experiment of simulated warming and habitat difference for litter decomposition of Zizania latifolia. A, Three habitats include air interface, water interface, and soil interface. Among them, litter bags under air decomposition were hang over the bamboo (1.2 m from the ground), litter bags under water decomposition were floated in the surface of water (with the aids of table tennis), and litter bags under soil decomposition were fixed by PVC tubes in the soils (5.0 cm in deep). B, The design and operation of Open-top Chamber (OTC). Among them, control group has no OTC devices, and OTC devices simulate rising temperature (warming group). The device was constructed by solar panels with 2.4 m base and 2.0 m opening in diameter. The temperatures between control and warming groups were recorded from December 2014 to December 2015 (once per hour). In warming treatment, the temperature has been raised by 1.5-2.0 ℃. C, The research object was a typical emergent wetland plant, Zizania latifolia. Its leaf litter was subjected to warming and habitat difference treatments.

图2 茭草叶凋落物质量残留率的季节性动态(平均值±标准误差, n = 3)。利用Post Hoc Tests进行两两比较分析, 不同小写字母代表处理之间的差异达到显著水平(p < 0.05)。

Fig. 2 Seasonal dynamics in mass remaining of leaf litter from Zizania latifolia (mean ± SE, n = 3). The different lowercase letters above error bars indicate significant differences between treatments by Post Hoc Tests (p < 0.05).

图3 茭草凋落物叶际微生物菌落平板计数(平均值±标准误差)。 *, p < 0.05; **, p < 0.01。

Fig. 3 Microbial colony counts in culture dish for leaf litter of Zizania latifolia (mean ± SE). *, p < 0.05; **, p < 0.01.

图4 茭草凋落物叶际细菌群落多样性指数(Chao1)及细菌在属分类水平上的群落结构特征。图中误差线为标准误差(n = 3), 利用Post Hoc Tests进行两两比较分析, 不同小写字母代表处理之间的差异达到显著水平(p < 0.05)。

Fig. 4 Diversity of bacterial community indicated by Chao1 index and the bacterial community composition at the genus level for leaf litter of Zizania latifolia. The error bars represent standard errors (n = 3), and the different lowercase letters above error bars indicate significant differences between treatments by Post Hoc Tests (p < 0.05).

图5 茭草凋落物叶际微生物碳源利用的平均颜色变化率(AWCD)值动态变化(培养时间为12-168 h)。图中误差线为标准误差(n = 3), 利用Post Hoc Tests进行两两比较分析, 不同小写字母代表处理之间的差异达到显著水平(p < 0.05)。

Fig. 5 Dynamics in average well color development (AWCD) value for carbon sources utilized by litter phyllospheric microorganisms of Zizania latifolia during an incubation period of 12-168 h. The error bars represent standard errors (n = 3), and the different lowercase letters above error bars indicate significant differences between treatments by Post Hoc Tests (p < 0.05).

图6 茭草凋落物叶际微生物对六大类碳源的利用情况。

Fig. 6 Utilization of six major groups of carbon sources by litter phyllospheric microorganisms of Zizania latifolia.

图7 相似性分析比较对照组与增温组、大气界面与水界面、大气界面与土界面、水界面与土界面的微生物碳源利用差异贡献度热图。颜色变化(从蓝到红色)代表不同碳源对差异的相对贡献度变化(0到100%)。观测样品为72-96 h的碳源利用情况。

Fig. 7 Similarity analysis shows the contribution of different carbon sources to the dissimilarity between control vs. warming, air interface vs. water interface, air interface vs. soil interface, and water interface vs. soil interface, illustrated by heatmaps. The color (blue to red) represents the relative contribution of different carbon substrates (0-100%). The observations at 72-96 h incubation point were used for drawing the heatmaps.