Surprising relationships between soil pH and microbial biomass and activity in a northern hardwood forest
Surprising relationships between soil pH and microbial biomass and activity in a northern hardwood forest
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DOI：
10.1007/s10533-023-01031-0
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发表时间：
2023-03
期刊：
影响因子：
4
通讯作者：
Renata Ontman;P. Groffman;C. Driscoll;Zhongqi Cheng
中科院分区：
文献类型：
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作者：
Renata Ontman;P. Groffman;C. Driscoll;Zhongqi Cheng
土壤微生物介导森林生态系统中主要的生态地球化学过程。土壤pH值被认为是一个“主变量”，对许多生态地球化学过程有很强的积极影响。为了更好地了解土壤pH值如何影响森林中的微生物活性和氮（N）动态，我们利用了一组长期测量的表层土壤pH值，N的可用性，和微生物生物量和呼吸的哈伯德布鲁克实验森林（HBEF），北方硬木林在新罕布什尔州，美国。我们比较了这些关系的强度在一个未经处理的流域，天然酸性土壤已被进一步酸化人为酸沉降，在附近的流域，在那里的土壤进行了硅酸钙处理，以改善酸沉降的影响。虽然我们期望观察到土壤pH值和微生物生物量和活性之间的强正相关关系，但我们却发现了弱和/或曲线关系。在许多情况下，微生物生物量和活性在出乎意料的低pH值（~ 4.5）时达到峰值，在较高pH值时下降，特别是在钙处理的土壤中。这是可能的复杂性，植物-微生物相互作用抑制和/或掩盖微生物对这些酸性土壤中pH值变化的反应。这些结果提出了关于pH值作为微生物过程的控制器以及生态系统如何响应酸沉积减少而恢复的问题。
Soil microbes mediate major biogeochemical processes in forest ecosystems. Soil pH is considered a “master variable” with a strong positive effect on many biogeochemical processes. To better understand how soil pH influences microbial activity and nitrogen (N) dynamics in forests, we utilized a set of long-term measurements of surface soil pH, N availability, and microbial biomass and respiration from the Hubbard Brook Experimental Forest (HBEF), a northern hardwood forest in New Hampshire, USA. We compared the strengths of these relationships in an unmanipulated watershed, where naturally acidic soils have been further acidified by anthropogenic acid deposition, to those in a nearby watershed, where soils were treated with calcium silicate to ameliorate the effects of acid deposition. While we expected to observe strong positive relationships between soil pH and microbial biomass and activity, we instead found weak and/or curvilinear relationships. In many cases, microbial biomass and activity peaked at unexpectedly low pH values (~ 4.5), and decreased at higher pH values, especially in the calcium-treated soils. It is likely that complexities in plant-microbial interactions inhibit and/or mask microbial response to changes in pH in these acidic soils. These results raise questions about pH as a controller of microbial processes and how ecosystems recover in response to decreases in acid deposition.