Seasonal variation in enzyme activities and temperature sensitivities in Arctic tundra soils
Seasonal variation in enzyme activities and temperature sensitivities in Arctic tundra soils
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DOI：
10.1111/j.1365-2486.2008.01819.x
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发表时间：
2009-07-01
影响因子：
11.6
通讯作者：
Schimel, Joshua P.
中科院分区：
文献类型：
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作者：
Wallenstein, Matthew D.;McMahon, Shawna K.;Schimel, Joshua P.
北极土壤中含有大量的有机物，因为碎屑分解速度非常慢。分解的第一步是由土壤微生物产生的胞外酶的活性引起的。我们假设潜在的酶活性相对于北极冻土带土壤中大量的有机物来说是低的，并且在原位温度下酶活性是低的。我们在4个取样日期测量了6种水解酶在4℃和20℃时的潜在活性，这些取样日期分别是在阿拉斯加州图里克湖的草丛、草丛间、灌木有机和灌木矿物土壤中。n -乙酰氨基葡萄糖苷酶、β -葡萄糖苷酶和肽酶的潜在活性在冬季结束时趋于最大，表明微生物在土壤冻结时产生酶。总的来说，在北极的夏季，酶的活性并没有增加，这表明在温度升高时，酶的生产受到氮的限制。我们还检测了土壤酶的温度敏感性（Q(10)）的季节变化。总体而言，冬末土壤酶库对温度的敏感性高于夏季。基于测量的酶活性、温度敏感性和日土壤温度数据，我们模拟了草丛和灌木有机土壤中潜在的原位β -葡萄糖苷酶活性。模拟原位酶活性在春季短暂增加，然后在整个夏季下降。在灌丛土壤中，模拟酶活性在春季解冻至8月初期间增加，然后在夏末和冬季期间下降。总的来说，温度是导致北极地区原位酶活性降低的最强因素。然而，在夏季，酶活性较低，可能是由于酶生产的n限制，这将限制酶活性在短暂的时间内，否则温度将推动更高的分解速度。
Arctic soils contain large amounts of organic matter due to very slow rates of detritus decomposition. The first step in decomposition results from the activity of extracellular enzymes produced by soil microbes. We hypothesized that potential enzyme activities are low relative to the large stocks of organic matter in Arctic tundra soils, and that enzyme activity is low at in situ temperatures. We measured the potential activity of six hydrolytic enzymes at 4 and 20 degrees C on four sampling dates in tussock, intertussock, shrub organic, and shrub mineral soils at Toolik Lake, Alaska. Potential activities of N-acetyl glucosaminidase, beta-glucosidase, and peptidase tended to be greatest at the end of winter, suggesting that microbes produced enzymes while soils were frozen. In general, enzyme activities did not increase during the Arctic summer, suggesting that enzyme production is N-limited during the period when temperatures would otherwise drive higher enzyme activity in situ. We also detected seasonal variations in the temperature sensitivity (Q(10)) of soil enzymes. In general, soil enzyme pools were more sensitive to temperature at the end of the winter than during the summer. We modeled potential in situ beta-glucosidase activities for tussock and shrub organic soils based on measured enzyme activities, temperature sensitivities, and daily soil temperature data. Modeled in situ enzyme activity in tussock soils increased briefly during the spring, then declined through the summer. In shrub soils, modeled enzyme activities increased through the spring thaw into early August, and then declined through the late summer and into winter. Overall, temperature is the strongest factor driving low in situ enzyme activities in the Arctic. However, enzyme activity was low during the summer, possibly due to N-limitation of enzyme production, which would constrain enzyme activity during the brief period when temperatures would otherwise drive higher rates of decomposition.