Great and fast increase in soil CH4 uptake after reforestation in karst cropland area is linked to the environmental and microbial factors
Great and fast increase in soil CH4 uptake after reforestation in karst cropland area is linked to the environmental and microbial factors
复制标题
喀斯特农田地区重新造林后土壤 CH4 吸收量大幅快速增加与环境和微生物因素有关
DOI：
10.1016/j.agee.2023.108367
复制
发表时间：
2023-01-26
影响因子：
6.6
通讯作者：
Ma，Bo
中科院分区：
文献类型：
--
作者：
Liu，Fang;Wang，Shilu;Ma，Bo
岩溶环境是一个重要的，但往往被忽视的全球大气CH 4汇。岩溶土壤中甲烷氧化细菌群落的研究知之甚少，因此，土地利用变化（LUC）和土壤管理措施对甲烷氧化细菌群落的影响以及甲烷氧化细菌作为土壤CH 4汇的作用机制尚不清楚。本研究比较了喀斯特地区5个不同土壤类型和土地利用方式的土壤CH 4净通量、CH 4氧化动力学参数（K和Vmax）以及CH 4氧化剂的pmoA基因。最大的大气CH 4吸收率（−5.62 ± 3.14 kg ha-1 y-1）出现在恢复灌木林地中，它们被用于农作物种植后仅10年;其次是石灰石土壤中的天然林（−4.30 ± 4.02 kg ha-1 y-1）。农田耕作土壤向大气排放CH 4。农田土壤和从农田恢复的灌木林地土壤之间的CH 4净通量差异（−8.21 kg ha-1 y-1）是全球平均值的4-8倍，这表明喀斯特农田地区石灰岩土壤上的重新造林比非喀斯特地区更有可能增强土壤CH 4氧化。土壤水分是最有可能引发造林增强效应的环境因子。Km、土壤CH 4净通量和甲烷氧化组分之间存在显著的对应关系，表明细菌在调节LUC对土壤CH 4氧化速率的影响中起着重要作用。在石灰岩土壤上，人工造林后，Ⅰ型甲烷氧化菌USCγ和JR 3（USCγsensu lato）在促进土壤氧化大气CH 4中起主导作用，而非以往研究中的Ⅱ型甲烷氧化菌USCα。喀斯特环境中特定的不稳定生境有利于USCγ，USC γ作为r-策略者，可以迅速改变以适应LUC形成的新条件，然后可能以指数速度增长。这种环境因素和微生物因素的耦合可以很好地解释石灰岩土壤中CH 4氧化的巨大而快速的响应。我们的研究提供了新的见解，在喀斯特地区的农田造林可能是一个明显更有效的方式来潜在地减轻大气中的CH 4积累，因此应该大力鼓励。
Karst environments are an important but often overlooked global sink of atmospheric CH4. Little is known about methanotrophic bacterial communities in karst soils; consequently, the effects of land use change (LUC) and soil management practices on them and how they function as part of the soil CH4sink are unclear. In this study, we compared net soil CH4fluxes, kinetic parameters (Kmand Vmax) of CH4oxidation, and thepmoAgene of CH4oxidizers at five test soil plots in karst areas that have different soil types and land use types. The maximum atmospheric CH4uptake rate (−5.62 ± 3.14 kg ha-1y-1) occurred in reverting scrublands just 10 years after they had been utilized for crop cultivation; followed by natural forest (−4.30 ± 4.02 kg ha-1y-1) in limestone soils. The cultivated soils in the cropland emitted CH4into the atmosphere. The difference in net CH4fluxes (−8.21 kg ha–1y–1) between soils in cropland and soils in reverting scrubland from cropland was 4–8 times higher than the global average values, suggesting that reforestation on limestone soils in karst cropland areas has much greater potential to enhance soil CH4oxidation than in non-karst areas. Soil moisture is the most likely environmental factor to trigger the enhancement effect of reforestation. The remarkable corresponding relationships between Km, net soil CH4fluxes, and methanotrophic compositions in these plots suggest that bacteria play an essential role in regulating the effects of LUC on soil CH4oxidation rates. It is type Ⅰ methanotroph USCγ and JR3 (USCγsensu lato), not type II methanotrophs USCα as in previous studies, that dominate in enhancing soil oxidation of atmospheric CH4since reforestation on limestone soils. The specific unstable habitats in karst settings favor USCγ who, as r-strategists, can change rapidly to adapt to new conditions formed from LUC and then grow presumably at an exponential rate. This coupling of environmental and microbial factors can well explain the great and fast response of CH4oxidation in limestone soils. Our study provides new insights that reforestation of cropland in karst areas may be a noticeably more efficient way to potentially mitigate atmospheric CH4build-up and thus should be strongly encouraged.