Effects of fire temperature on the physical and chemical characteristics of the ash from two plots of cork oak (Quercus suber)
Effects of fire temperature on the physical and chemical characteristics of the ash from two plots of cork oak (Quercus suber)
复制标题
火灾温度对两块栓皮栎灰分理化特性的影响
DOI：
10.1002/ldr.930
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发表时间：
2009
影响因子：
4.7
通讯作者：
Deborah A. Martin
中科院分区：
文献类型：
--
作者：
X. Úbeda;Paulo Pereira;L. Outeiro;Deborah A. Martin
软木栎属(Quercus Suber)广泛分布于地中海地区，是火灾多发地区。燃烧产生的灰烬可能会对土壤状况和水资源产生影响，这些影响可能会因火灾期间达到的温度和凋落物的特征而有所不同，凋落物的特征被定义为火灾前积累在土壤表面的死有机物。这项工作的目的是确定实验室实验中产生的灰烬的物理和化学特性，以接近该地区火灾的典型条件。从伊比利亚半岛两个不同的样地--Mas BAssets(加泰罗尼亚)和Albufeira(葡萄牙)采集的栎木凋落物在不同温度下燃烧2 h，测量了质量损失(ML%)、灰分颜色和CaCO_3含量、pH、电导率(EC)和从灰分和去离子水混合产生的灰浆中释放出的主要阳离子(Ca~(2+)、Mg~(2+)、K~+和Na~+)。结果表明，除550℃外，Albufeira样品的ML%在所有温度下都高于Mas B Assets样品，且其损失率随温度的增加比Mas B Assets样品更快。在150°C时，灰烬呈淡黄色，在200-250°C时变红，在300°C时变黑。高于400°C时，灰烬为灰/白色。这种热降解主要发生在Albufeira枯枝落叶中。Albufeira凋落物中CaCO3的形成是在较低的温度下确定的。在温度<； 300°C时，pH和EC值较低，在较高温度下升高，特别是在阿尔布费拉浆料中。在较低温度下，除镁离子外，阳离子浓度与未烧成的样品没有显著差异。阳离子浓度在中温时增加，在较高温度下降低，尤其是二价阳离子的浓度。在中等温度下，单价阳离子表现出较大的浓度，主要存在于Albufeira灰浆中。钙镁比的分析还表明，在相同的温度下，Albufeira凋落物的严重程度越高。在中等和较高温度下观察到对土壤性质的潜在负面影响。这些负面影响包括更高的质量损失百分比，这意味着更多的土壤可能受到侵蚀，更高的pH值和更多的阳离子从灰烬中释放，特别是单价阳离子(K+，Na+)的比例高于二价离子(钙，镁)，这可能会对土壤物理性质(如团聚体稳定性)造成影响。此外，灰烬中的离子可能会改变土壤化学，这可能对一些植物有害，从而改变这些生态系统在火灾后的恢复。低强度的规定火可以是这些地点土地管理的有用工具，因为火温度对地表凋落物的物理和化学性质的影响减少了，并可以通过减少燃料负荷来降低高温野地火灾的风险。从水资源的角度来看，较低的火灾温度对陆上水流的化学成分影响较小，土壤表面被侵蚀的可能性也较小。版权所有©2009 John Wiley&Sons，Ltd.
Cork oak, (Quercus suber) is widely distributed in the Mediterranean region, an area subject to frequent fires. The ash produced by burning can have impacts on the soil status and water resources that can differ according to the temperature reached during fire and the characteristics of the litter, defined as the dead organic matter accumulated on the soil surface prior to the fire. The aim of this work is to determine the physical and chemical characteristics of ash produced in laboratory experiments to approximate conditions typical of fires in this region. The litter of Quercus suber collected from two different plots on the Iberian Peninsula, Mas Bassets (Catalonia) and Albufeira (Portugal), was combusted at different temperatures for 2 h. We measured Mass Loss (ML per cent), ash colour and CaCO3 content, pH, Electrical Conductivity (EC) and the major cations (Ca2+, Mg2+, K+ and Na+) released from ash slurries created by mixing ash with deionized water. The results showed that ML per cent is higher at all temperatures in Albufeira samples compared to Mas Bassets samples, except at 550°C, and the rate of loss increases faster with temperature than the Mas Bassets samples. At 150°C the ash colour is yellowish, becoming reddish at 200–250°C and black at 300°C. Above 400°C the ash is grey/white. This thermal degradation is mostly observed in Albufeira litter. The formation of CaCO3 was identified at a lower temperature in Albufeira litter. At temperatures < 300°C, pH and EC values are lower, rising at higher temperatures, especially in Albufeira slurries. The concentration of cations at lower temperatures does not differ substantially from the unburned sample except for Mg2+. The cation concentration increases at medium temperatures and decrease at higher temperatures, especially the concentration of divalent cations. The monovalent cations showed a larger concentration at moderate temperatures, mainly in Albufeira ash slurries. The analysis of the Ca:Mg ratio also showed that for the same temperature, a higher severity results for Albufeira litter. Potential negative effects on soil properties are observed at medium and higher temperatures. These negative effects include a higher percentage of mass loss, meaning more soil may be exposed to erosion, higher pH values and greater cation release from ash, especially monovalalent cations (K+, Na+) in higher proportions than the divalent ions (Ca2+, Mg2+), that can lead to impacts on soil physical properties like aggregate stability. Furthermore, the ions in ash may alter soil chemistry which may be detrimental to some plants thus altering the recovery of these ecosystems after fire. Low intensity prescribed fire can be a useful tool to land management in these sites, due to the reduced effects of fire temperatures on the physical and chemical properties of surface litter, and can reduce the risk of high temperature wildland fires by reducing fuel loadings. From the perspective of water resources, lower fire temperatures produce fewer impacts on the chemistry of overland flow and there is less probability that the soil surface will be eroded. Copyright © 2009 John Wiley & Sons, Ltd.