Departamento de Ciencias Ambientales, Universidad de Castilla-La Mancha, Campus Fábrica de Armas, E-45071 Toledo, Spain.
Departamento de Ciencias Ambientales, Universidad de Castilla-La Mancha, Campus Fábrica de Armas, E-45071 Toledo, Spain.
Sci Total Environ. 2021 Jan 15;752:141877. doi: 10.1016/j.scitotenv.2020.141877. Epub 2020 Aug 24.
Spatial heterogeneity of soil properties plays a major role in regulating ecosystem structure and functioning. In general, soil resources accumulate beneath woody plant-covered patches more than in the open interspace, making them function as fertility islands. Whilst wildfire is a common disturbance, little information is available on the role of particular plant species in maintaining soil fertility underneath in areas that are subjected to recurrent fires. This is an important issue given that land abandonment, together with a warmer and drier climate, is increasing fire danger in regions such as the Mediterranean. We determined whether increasing fire frequency, producing changes from a Quercus ilex L., woodland to a shrubland, modifies the effect of woody plant canopy on soil fertility. Additionally, the effect of fire history on species-specific leaf and litter nutrient concentration was assessed. Areas affected by none, one, two or three fires were selected. Within each area, soil fertility was measured underneath Cistus ladanifer L., Retama sphaerocarpa L., Phillyrea angustifolia L. and Quercus ilex canopies and in open interspace. Unburned soils located underneath P. angustifolia and Q. ilex canopies were significantly more fertile than in open interspaces. The microsite effect on soil fertility was fire frequency dependent. As fire frequency increased, the plant canopy microsite effect decreased for soil organic matter (SOM), cation exchange capacity (CEC), total C, P, Ca, K and Mg, labile phosphate, arylsulfatase and acid phosphatase activities. Total N, ammonium, nitrate and β-glucosidase activity decreased with increasing fire frequency, but their spatial variability was maintained along all fire frequency scenarios. Fire frequency decreased foliar N concentration but increased P concentration in some species, leading to a decrease in their N:P ratio. Our findings suggest that soil fertility heterogeneity will be reduced with increasing fire frequency. This could compromise the recovery of soil and ecosystem functioning.
土壤属性的空间异质性在调节生态系统结构和功能方面起着重要作用。一般来说，在有木本植物覆盖的斑块下，土壤资源比开阔的空地积累得更多，使它们成为肥力岛。虽然野火是一种常见的干扰，但关于在经常发生火灾的地区，特定植物物种在维持土壤肥力方面的作用的信息很少。鉴于土地废弃以及更温暖和干燥的气候正在增加地中海等地区的火灾危险，这是一个重要的问题。我们确定了增加火灾频率，使从 Quercus ilex L. 的林地变为灌丛，是否会改变木本植物冠层对土壤肥力的影响。此外，还评估了火灾历史对特定物种叶片和凋落物养分浓度的影响。选择了未受影响、受一次、两次或三次火灾影响的区域。在每个区域内，测量了 Cistus ladanifer L.、Retama sphaerocarpa L.、Phillyrea angustifolia L. 和 Quercus ilex 树冠下以及开阔空地的土壤肥力。未燃烧的土壤位于 P. angustifolia 和 Q. ilex 树冠下的土壤明显比开阔空地肥沃。微生境对土壤肥力的影响取决于火灾频率。随着火灾频率的增加，土壤有机质 (SOM)、阳离子交换能力 (CEC)、总 C、P、Ca、K 和 Mg、可利用磷酸盐、芳基硫酸酯酶和酸性磷酸酶活性的植物冠层微生境效应降低。随着火灾频率的增加，总 N、铵、硝酸盐和 β-葡萄糖苷酶活性降低，但在所有火灾频率情况下，其空间变异性得以维持。火灾频率降低了叶片 N 浓度，但增加了一些物种的 P 浓度，导致其 N:P 比降低。我们的研究结果表明，随着火灾频率的增加，土壤肥力异质性将会降低。这可能会影响土壤和生态系统功能的恢复。
