Department of Soil Science, Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena, Germany.
Medical Center LMU Munich, Ziemssenstraße 1, 80336 München, Germany.
Sci Total Environ. 2017 Dec 15;605-606:514-526. doi: 10.1016/j.scitotenv.2017.06.182. Epub 2017 Jun 30.
Land-use type and ecosystem disturbances are important drivers for element cycling and bear the potential to modulate soil processes and hence ecosystem functions. To better understand the effect of such drivers on the magnitude and temporal patterns of organic matter (OM) and associated nutrient fluxes in soils, continuous flux monitoring is indispensable but insufficiently studied yet. We conducted a field study to elucidate the impact of land-use and surface fires on OM and nutrient fluxes with soil solution regarding seasonal and temporal patterns analyzing short (<3months) and medium-term (3-12months) effects. Control and prescribed fire-treated topsoil horizons in beech forests and pastures were monitored biweekly for dissolved and particulate OM (DOM, POM) and solution chemistry (pH value, elements: Ca, Mg, Na, K, Al, Fe, Mn, P, S, Si) over one post-fire year. Linear mixed model analyses exhibited that mean annual DOM and POM fluxes did not differ between the two land-use types, but were subjected to strong seasonal patterns. Fire disturbance significantly lowered the annual soil solution pH in both land-uses and increased water fluxes, while DOC fluxes remained unaffected. A positive response of POC and S to fire was limited to short-term effects, while amplified particulate and dissolved nitrogen fluxes were observed in the longer run and co-ocurred with accelerated Ca and Mg fluxes. In summary, surface fires generated stronger effects on element fluxes than the land-use. Fire-induced increases in POM fluxes suggest that the particulate fraction represent a major pathway of OM translocation into the subsoil and beyond. With regard to ecosystem functions, pasture ecosystems were less prone to the risk of nutrient losses following fire events than the forest. In pastures, fire-induced base cation export may accelerate soil acidification, consequently exhausting soil buffer systems and thus may reduce the resilience to acidic depositions and disturbances.
土地利用类型和生态系统干扰是元素循环的重要驱动因素，具有调节土壤过程进而影响生态系统功能的潜力。为了更好地理解这些驱动因素对土壤中有机质（OM）和相关养分通量的大小和时间格局的影响，连续通量监测是必不可少的，但目前研究还不够充分。我们进行了一项实地研究，阐明了土地利用和地表火对 OM 和养分通量的影响，并结合土壤溶液中的季节性和时间格局分析了短期（<3 个月）和中期（3-12 个月）效应。在一个火后年份中，我们对山毛榉林和牧草地的控制和规定火烧处理表土层进行了双周监测，以分析溶解和颗粒有机质（DOM、POM）和溶液化学（pH 值、元素：Ca、Mg、Na、K、Al、Fe、Mn、P、S、Si）的短期（<3 个月）和中期（3-12 个月）效应。线性混合模型分析表明，两种土地利用类型之间的年平均 DOM 和 POM 通量没有差异，但受强烈的季节性模式影响。火干扰显著降低了两种土地利用类型的土壤溶液 pH 值，并增加了水通量，而 DOC 通量不受影响。POC 和 S 对火的正向响应仅限于短期效应，而较长时间内观察到放大的颗粒态和溶解态氮通量，同时伴随着 Ca 和 Mg 通量的加速。总的来说，地表火对元素通量的影响大于土地利用类型。火引起的 POM 通量增加表明，颗粒态部分是 OM 向次表层和更深层迁移的主要途径。就生态系统功能而言，与森林相比，牧草地生态系统在火事件后发生养分损失的风险较低。在牧草地上，火引起的基础阳离子输出可能加速土壤酸化，从而耗尽土壤缓冲系统，从而可能降低对酸性沉降和干扰的恢复能力。
