Primary productivity as a control over soil microbial diversity along environmental gradients in a polar desert ecosystem.
Primary productivity as a control over soil microbial diversity along environmental gradients in a polar desert ecosystem.
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作者：
Geyer KM;Takacs-Vesbach CD;Gooseff MN;Barrett JE
初级生产是食物网和生态系统的基本能量来源，因此是对土壤群落的一个重要制约。这种耦合在极地陆地生态系统中特别明显，在那里，生物多样性和活动受到土壤生产力梯度的严格限制（例如，土壤水分，有机碳的可用性）和地球化学严重性（例如，pH、电导率）。在南极洲的麦克默多干谷，环境梯度决定了土壤群落的许多特性，但对该地区的毛初级生产力或净初级生产力（GPP，NPP）的估计相对较少。在这里，我们描述了一个调查，利用脉冲幅度调制（PAM）荧光法估计率GPP在一个广泛的环境梯度沿着与地下微生物多样性和分解。PAM对全球初级生产力的估计值范围从最干旱土壤的平均0.27 μ mol O2/m2/s到最高产土壤的平均6.97 μ mol O2/m2/s，后者相当于假定60天生长期的年NPP为217 g C/m2/y。四种碳获取酶活性的多样性指数也随着土壤生产力的增加而增加，这表明中温环境中有机基质的多样性可能是微生物多样性的另一个驱动因素。总的来说，土壤生产力是一个更强的预测微生物多样性和酶活性比任何地球化学严重程度的估计。这些结果强调了环境梯度在控制干旱系统中群落多样性和生态系统尺度碳库动态方面的基本作用。
Primary production is the fundamental source of energy to foodwebs and ecosystems, and is thus an important constraint on soil communities. This coupling is particularly evident in polar terrestrial ecosystems where biological diversity and activity is tightly constrained by edaphic gradients of productivity (e.g., soil moisture, organic carbon availability) and geochemical severity (e.g., pH, electrical conductivity). In the McMurdo Dry Valleys of Antarctica, environmental gradients determine numerous properties of soil communities and yet relatively few estimates of gross or net primary productivity (GPP, NPP) exist for this region. Here we describe a survey utilizing pulse amplitude modulation (PAM) fluorometry to estimate rates of GPP across a broad environmental gradient along with belowground microbial diversity and decomposition. PAM estimates of GPP ranged from an average of 0.27 μmol O2/m2/s in the most arid soils to an average of 6.97 μmol O2/m2/s in the most productive soils, the latter equivalent to 217 g C/m2/y in annual NPP assuming a 60 day growing season. A diversity index of four carbon-acquiring enzyme activities also increased with soil productivity, suggesting that the diversity of organic substrates in mesic environments may be an additional driver of microbial diversity. Overall, soil productivity was a stronger predictor of microbial diversity and enzymatic activity than any estimate of geochemical severity. These results highlight the fundamental role of environmental gradients to control community diversity and the dynamics of ecosystem-scale carbon pools in arid systems.
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