Increasing fire severity and frequency may stress ecosystems also impacted by climate change. We studied the physical limitations to regeneration after fire in an ecosystem that already experiences high summer temperatures and drought and is therefore a possible analog of the future. We compared soil respiration as an indicator of microbial activity in burned and unburned forest soils in central Texas, where two recent wildfires have occurred (2011 and 2015). We also measured soil temperature, water content, soil water δ¹⁸O and δD values, total C, N, pH, and δ¹³C values of total organic matter. Burned soils had lower total C and N than unburned soils; however, lab‐based respiration measurements, which controlled for temperature and water content, suggest that microbial activity in burned and unburned soils are similar. Conversely, field measurements show that during hot and dry months respiration rates in burned soils were much lower than they were in unburned soils due to differences in soil temperature and water content. Soil temperature at 5 cm reached 60°C in burned soils due to the removal of canopy cover, the removal of organic matter insulation, and the deposition of black ash on the soil surface. Higher temperatures increased evaporation as indicated by significantly lower deuterium excess of water in soils burned in 2015 than unburned soils. If the disturbance of vegetation by fire is substantial enough, the resulting perturbations to soils persist for years, most importantly increased heat absorption which results in lower water contents and ultimately reduced microbial activity.

中文翻译：

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在干热气候下的野火后，多年以来土壤水含量和呼吸速率降低

火灾的严重程度和发生频率的增加可能给生态系统带来压力，该生态系统也受到气候变化的影响。我们在已经经历了夏季高温和干旱的生态系统中研究了火灾后再生的物理限制，因此可以作为未来的类似物。我们比较了土壤呼吸作为德克萨斯州中部已燃烧和未燃烧森林土壤中微生物活动的指标，该州最近发生过两次野火（2011年和2015年）。我们还测量土壤温度，含水率，土壤水分δ ¹⁸ O和δD值，总的C，N，pH值，和δ ¹³总有机物的C值。烧过的土壤的总碳和氮比未烧过的土壤低。但是，基于实验室的呼吸测量可控制温度和水分含量，表明燃烧的土壤和未燃烧的土壤中的微生物活性相似。相反，实地测量表明，由于土壤温度和水分含量的差异，在炎热和干燥的月份中，燃烧过的土壤中的呼吸速率远低于未燃烧过的土壤中的呼吸速率。由于去除了冠层覆盖层，去除了有机质绝缘层以及黑灰在土壤表面的沉积，烧过的土壤中5 cm处的土壤温度达到60°C。2015年燃烧的土壤中氘的过量水含量明显低于未燃烧的土壤，这表明较高的温度增加了蒸发量。