Prescribed fire is commonly used in southeastern US forests and is being more widely applied in fire-prone ecosystems elsewhere. Research on direct effects of burning has focused on aboveground impacts to plants with less attention to belowground effects. We measured soil heating during experimental burns in longleaf pine sandhill and flatwoods ecosystems in the southeastern US. Soil heating was minimal in frequently burned sites. Where fire had been excluded for several decades, however, we detected substantial soil heating sustained for considerable durations. Long-duration heating was most prominent where accumulated forest floor duff (Oe and Oa organic horizons) was deepest, particularly at the base of mature pines in long-unburned sites. Temperatures potentially lethal to plant tissues (≥60°C) were sustained for several hours as deep as 10 cm near pines in flatwoods sites. Sustained temperatures ≥300°C, when impacts to soil nutrients can occur, were observed for up to 35 min at mineral soil surfaces. Patterns of heating were similar in long-unburned sandhill sites; however, temperatures were generally lower and durations more brief. Heat transfer resulting from smoldering in forest floor duff deserves further attention to predict mineral soil heating, forecast fire effects, and inform restoration efforts in fire-prone ecosystems.

中文翻译：

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长叶松树生态系统中森林地板粉屑的闷烧导致土壤长期升温

规定的火灾通常在美国东南部的森林中使用，并在其他地方易发火灾的生态系统中得到更广泛的应用。关于燃烧的直接影响的研究集中在地上对植物的影响上，而对地下影响的关注则较少。我们在美国东南部的长叶松树沙丘和扁平木生态系统中的实验性烧伤过程中测量了土壤加热。在经常燃烧的地方，土壤加热很少。但是，在数十年来一直没有发生火灾的地方，我们发现相当长一段时间内持续大量的土壤加热。在积聚的林底粉屑（Oe和Oa有机层）最深的地方，长时间加热最为突出，尤其是在长时间未燃烧的土地上成熟松树的底部。可能在植物体内致死的温度（≥60°C）持续数小时，直至在阔叶林的松树附近深达10 cm。在矿物土壤表面观察到长达35分钟的持续温度≥300°C时，会影响土壤养分。在长时间未燃烧的沙丘地区，加热方式相似。但是，温度通常较低，持续时间较短。森林地板粉尘中闷烧产生的热传递值得进一步关注，以预测矿物土壤的加热，预测火的影响并为易火生态系统的恢复工作提供信息。温度通常较低，持续时间较短。森林地板粉尘中闷烧产生的热传递值得进一步关注，以预测矿物土壤的加热，预测火的影响并为易火生态系统的恢复工作提供信息。温度通常较低，持续时间较短。森林地板粉尘中闷烧产生的热传递值得进一步关注，以预测矿物土壤的加热，预测火的影响并为易火生态系统的恢复工作提供信息。