Our understanding of tundra fire effects in Northern Alaska is limited because fires have been relatively rare. We sampled a 70+ year-old burn visible in a 1948 aerial photograph for vegetation composition and structure, soil attributes, terrain rugosity, and thermokarst pit density. Between 1948 and 2017 the burn initially became wetter as ice wedges melted but then drained and dried as the troughs became hydrologically connected. The reference tundra has become wetter over the last few decades and appears to be lagging through a similar sequence. The burn averaged 2.5 °C warmer than the reference tundra at 30 cm depth. Thinning of organic soil following fire appears to dramatically accelerate the background degradation of ground-ice features in response to climate change and promotes a plant community that is distinct in terms of taxa and structure, dominated by tall willows and other competitive, rather than cold-tolerant, species. The cover of sedges and mosses is low while that of willows and grass is high relative to the reference tundra. The changes in plant community composition and structure, increasing ground temperature, and thermokarst lead us to expect the observed biophysical changes to the tundra will persist centuries into the future.

我们对阿拉斯加北部苔原火灾影响的了解有限，因为火灾相对罕见。我们对 1948 年航空照片中可见的 70 多年的烧伤点进行了采样，以了解植被组成和结构、土壤属性、地形崎岖度和热喀斯特坑密度。1948 年至 2017 年间，随着冰楔融化，燃烧区域最初变得更加湿润，但随着槽在水文上的连接，燃烧区域逐渐排水和干燥。过去几十年来，参考苔原变得更加湿润，并且似乎经历了类似的滞后过程。燃烧深度比 30 厘米深度的参考苔原平均高 2.5 °C。火灾后的有机土壤变薄似乎会显着加速地面冰特征的背景退化，以应对气候变化，并促进植物群落在分类单元和结构方面具有独特性，以高柳和其他竞争性植物为主，而不是寒冷的植物。宽容, 物种. 相对于参考苔原，莎草和苔藓的覆盖度较低，而柳树和草的覆盖度较高。植物群落组成和结构的变化、地面温度的升高和热岩溶使我们预计观察到的苔原生物物理变化将持续几个世纪。