School of Forestry, Northern Arizona University, 200 E. Pine Knoll Drive, Flagstaff, Arizona, 86011, USA.
U.S. Geological Survey, Southwest Biological Science Center, 2290 SW. Resource Boulevard, Moab, Utah, 84532, USA.
Ecol Appl. 2019 Jul;29(5):e01908. doi: 10.1002/eap.1908. Epub 2019 Jun 12.
Land degradation is a persistent ecological problem in many arid and semiarid systems globally (drylands hereafter). Most instances of dryland degradation include some form of soil disturbance and/or soil erosion, which can hinder vegetation establishment and reduce ecosystem productivity. To combat soil erosion, researchers have identified a need for rehabilitation of biological soil crusts (biocrusts), a globally relevant community of organisms aggregating the soil surface and building soil fertility. Here, the impact of plant and biocrust cover was tested on soil erosion potential in the piñon-juniper woodlands of Bandelier National Monument, New Mexico, USA. Biocrusts were found to be similarly influential to vascular plants in reducing erosion, largely acting by promoting surface roughness. The potential to rehabilitate biocrusts within the Monument was also tested. Plots were inoculated on eroding soils before the summer monsoon with greenhouse-cultured biocrusts. In a full-factorial design, treatments to reduce or halt erosion were administered to the inoculated plots and their paired controls. These erosion-reduction treatments included barriers to overland flow (flashing), slash placement, and seeding of vascular plants. Dynamic changes to soil stability, penetration resistance, and extractable soil nutrients were observed through time, but no strong effects with the addition of biocrust inoculum, seeding, or erosion intervention treatments were seen. The results do suggest possible ways forward to successfully rehabilitate biocrust, including varying the timing of biocrust application, amending inoculum application with different types of soil stabilization techniques, and adding nutrients to soils. The insights gleaned from the lack of response brings us closer to developing effective techniques to arrest soil loss in these socially and ecologically important dryland systems.
土地退化是全球许多干旱和半干旱系统（以下简称旱地）长期存在的生态问题。大多数旱地退化的情况都包括某种形式的土壤扰动和/或土壤侵蚀，这会阻碍植被的建立并降低生态系统的生产力。为了防治土壤侵蚀，研究人员已经认识到需要对生物土壤结皮（biocrusts）进行修复，生物土壤结皮是一种在全球范围内聚集在土壤表面并提高土壤肥力的相关生物群落。在这里，研究人员测试了植物和生物土壤结皮覆盖对新墨西哥州班德利尔国家纪念碑（Bandelier National Monument）派尤尼昂-杰尼珀（piñon-juniper）林地土壤侵蚀潜力的影响。研究发现，生物土壤结皮在减少侵蚀方面与维管植物同样具有影响力，主要是通过促进地表粗糙度来发挥作用。研究还测试了在纪念碑内修复生物土壤结皮的潜力。在夏季季风来临之前，在侵蚀土壤上接种温室培养的生物土壤结皮。在一个完全因子设计中，对接种和对照的处理都采取了减少或阻止侵蚀的措施。这些减少侵蚀的处理措施包括对地表径流的障碍（闪蒸）、砍伐放置和维管植物的播种。随着时间的推移，观察到土壤稳定性、穿透阻力和可提取土壤养分的动态变化，但在添加生物土壤结皮接种物、播种或侵蚀干预处理方面没有看到明显的效果。研究结果表明，成功修复生物土壤结皮的可能途径包括改变生物土壤结皮应用的时间、用不同类型的土壤稳定技术改进接种物的应用以及向土壤中添加养分。缺乏响应的结果使我们更接近于开发出在这些具有社会和生态重要性的旱地系统中有效阻止土壤流失的技术。
