Biocrusts enhance non-rainfall water deposition and alter its distribution in dryland soils
Biocrusts enhance non-rainfall water deposition and alter its distribution in dryland soils
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DOI：
10.1016/j.jhydrol.2021.126050
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发表时间：
2021-04
影响因子：
6.4
通讯作者：
Sheng-long Li;M. Bowker;B. Xiao
中科院分区：
文献类型：
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作者：
Sheng-long Li;M. Bowker;B. Xiao
非降雨水沉积是一种重要的水资源，对旱地植被和土壤生物群的生存以及维持旱地水平衡至关重要。生物结皮作为一种“活皮肤”，因其对非降雨水沉降的潜在积极影响而受到越来越多的关注。然而，生物壳对非降雨水的调节作用的大小和机制尚不清楚。在黄土高原半干旱区，采用连续称重式微蒸渗仪（0-3，3-6，6-10 cm），研究了裸土和3种生物结皮（蓝藻结皮、蓝藻-苔藓混合结皮和苔藓结皮）的非降雨水分沉积和分布。结果表明，生物结皮的日非降雨降水量显著高于裸土（13%~ 22%），且生物结皮类型对日非降雨降水量的影响顺序为：苔藓结皮>混合结皮>蓝藻结皮>裸土。生物结皮还与非降雨水形成速率更快有关（42%;F≥ 2.87，P ≤ 0.04），这可能与裸地相比夜间冷却更快有关。大气水汽凝结是0-10 cm深度非降雨水沉降的主要水源，而土壤水汽凝结则相反。生物结皮有较高的凝结从两个来源，并有相对更多的沉积从大气中：大气中的蒸汽凝结大114%-143%，土壤蒸汽凝结大20%-30%。非降雨水量的69%以上集中在土壤表层3cm处。土壤表层生物结皮的强烈影响（F= 45.34，P < 0.001）是造成非降雨水沉积差异的主要原因。此外，生物结皮对非降雨水分沉积和分布的影响主要是由于其对土壤理化性质的影响，特别是对土壤细颗粒、有机质、土壤粗糙度、日温差和苔藓形态的影响。总之，生物结皮具有更强的非降雨水沉积能力，并改变非降雨水沿着土壤深度的分布，在旱地生态系统表层土壤水分平衡中起着重要作用。
Non-rainfall water deposition is an important water resource, critical for the survival of dryland vegetation and soil biota and maintaining dryland water balance. As a “living skin”, biocrusts are attracting increasing attention due to their potentially positive impacts on non-rainfall water deposition. However, the magnitude and underlying mechanisms of biocrust regulation of non-rainfall water are still unclear. In this study, we investigated the non-rainfall water deposition and distribution through continuous weighing micro-lysimeters (0–3, 3–6, and 6–10 cm depths) with bare soil and three types of biocrusts (cyanobacterial crusts, cyanobacterial-moss mixed crusts, and moss crusts) in a semiarid region of the Chinese Loess Plateau. Our results showed that the biocrusts were associated with significantly greater non-rainfall water deposition capacity (~13%–22%) in contrast to the bare soil, and biocrust type strongly influenced the daily non-rainfall water amount in the order: moss crusts > mixed crusts > cyanobacterial crusts > bare soil. Biocrusts were also associated with faster rates of non-rainfall water formation (42%;F≥ 2.87,P≤ 0.04), which may be linked to faster nighttime cooling in comparison to the bare soil. Atmospheric vapor condensation was the primary water source for non-rainfall water deposition at the 0–10 cm depth, as opposed to soil vapor condensation. Biocrusts had higher condensation from both sources, and had relatively more deposition from the atmosphere: atmospheric vapor condensation was greater by 114%-143% and soil vapor condensation was greater by 20%–30%. Moreover, >69% of the total non-rainfall water amount occurred in the top 3 cm of soil. The strong biocrust influence in the uppermost centimeters (F= 45.34,P< 0.001) appears to primarily drive the contrasts in non-rainfall water deposition in soils. Furthermore, all of the apparent effects of biocrusts on non-rainfall water deposition and distribution were reasonably attributed to the biocrust influences on soil physicochemical properties, especially the contents of fine particles, organic matter, high soil roughness, daily temperature difference, and moss morphology. In conclusion, biocrusts are associated with much greater non-rainfall water deposition capacity, and change non-rainfall water distribution along with soil depth, implying that they play a critical role in surface soil water balance of dryland ecosystems.