College of Life Sciences, Shenyang Normal University, Shenyang, Liaoning 110034, China.
Department of Forestry, TP Cooper Building, University of Kentucky, Lexington, KY 40546, USA.
Sci Total Environ. 2019 Feb 15;651(Pt 2):2662-2670. doi: 10.1016/j.scitotenv.2018.10.164. Epub 2018 Oct 12.
Both topography and the occurrence of wildfire can strongly affect soil properties in forest successions. Although numerous studies have examined the effects of fire and topography, few have explored their shifting relative importance with time since fire. We measured physical, chemical, and biological soil properties in two topographic positions (north-facing and south-facing) in a Chinese boreal forest along a gradient of fire history. In the control site, topography strongly influenced soil properties, with north-facing slopes having higher soil moisture (SM), depth of organic matter layer (OML), total carbon and inorganic N concentrations, and lower pH, dissolved organic carbon (DOC) and nitrogen (DON). In the 1-year-post-fire site, wildfire erased topographic effects on soil variables, and greater changes in soil properties occurred on the north-facing slopes. The wildfire significantly increased soil pH, DON, ammonium and nitrate, and decreased SM, OML, DOC and microbial biomass, while no significant differences in soil properties appeared between high- and low-severity plots. In the 11-year-post-fire site, most soil properties were similar to the control except for microbial biomass, OML and DOC; topography again became a significant factor in explaining variations in soil properties. Fire severity was highly correlated only with soil pH in the 1-year-post-fire site, whereas topographic factors were always correlated with some soil properties in the three sites. In the 1-year-post-fire site, wildfire explained almost five times more variance than topography for most soil properties, whereas in the 11-year-post-fire site, the proportion of variance explained by topography increased and even surpassed that by wildfire. These results demonstrate that the resilience of Larix gmelinii forest soils might be controlled by wildfires in the short term but by topography in the long term.
地形和野火的发生强烈影响森林演替中的土壤特性。尽管许多研究都考察了火和地形的影响，但很少有研究探讨它们随火后时间推移而发生的相对重要性变化。我们在一个中国北方森林中，沿着火历史梯度的两个地形位置（北坡和南坡）测量了土壤物理、化学和生物特性。在对照点，地形强烈影响土壤特性，北坡的土壤水分（SM）、有机质层深度（OML）、总碳和无机 N 浓度较高，而 pH 值、溶解有机碳（DOC）和氮（DON）较低。在 1 年后的火灾点，野火消除了地形对土壤变量的影响，北坡的土壤特性变化更大。野火显著增加了土壤 pH 值、DON、铵和硝酸盐，降低了 SM、OML、DOC 和微生物生物量，而高和低严重度地块之间的土壤特性没有明显差异。在 11 年后的火灾点，除了微生物生物量、OML 和 DOC 外，大多数土壤特性与对照点相似；地形再次成为解释土壤特性变化的重要因素。在 1 年后的火灾点，火严重度仅与土壤 pH 值高度相关，而在三个点，地形因素始终与一些土壤特性相关。在 1 年后的火灾点，野火对大多数土壤特性的解释方差几乎是地形的五倍，而在 11 年后的火灾点，地形的解释方差比例增加，甚至超过了野火。这些结果表明，在短期内，落叶松林土壤的恢复力可能受到野火的控制，但在长期内可能受到地形的控制。
