Soil microbial response to Rhododendron understory removal in southern Appalachian forests: Effects on extracellular enzymes
Soil microbial response to Rhododendron understory removal in southern Appalachian forests: Effects on extracellular enzymes
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DOI：
10.1016/j.soilbio.2018.09.008
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发表时间：
2018-12
影响因子：
9.7
通讯作者：
Ernest D. Osburn;Katherine J. Elliottt;J. Knoepp;C. Miniat;John E. Barrett
中科院分区：
文献类型：
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作者：
Ernest D. Osburn;Katherine J. Elliottt;J. Knoepp;C. Miniat;John E. Barrett
大杜鹃是一种本土常绿灌木，随着美洲板栗 (Castanea dentata) 和东部铁杉 (Tsuga canadensis) 的减少，它在阿巴拉契亚森林中扩张。最大程度是森林管理者所关心的，因为它通过限制光和土壤养分的可用性来抑制阔叶树的生长。我们正在测试R。最大限度的砍伐作为促进阿巴拉契亚森林恢复的管理策略。我们假设 R.最大程度的去除将增加土壤氮 (N) 的可用性，从而导致微生物 C 需求增加（即增加 C 获取酶活性）并转向以细菌为主的微生物群落。最大去除处理应用于 2×2 析因设计，具有两个 R。最大树冠移除水平（移除与未移除）与两个 O 地平线移除水平（燃烧与未燃烧）相结合。去除后，我们对土壤进行了采样，发现溶解的有机碳 (DOC)、氮 (TDN、NO3、NH4) 和微生物生物量均随 R 的增加而增加。最大冠层 + O 地平线移除。此外，我们观察到随着冠层+O-地平线的去除，参与降解纤维素（β-葡萄糖苷酶）和半纤维素（β-木糖苷酶）的C-获取酶有所增加。尽管所有处理的 F:B 比率从春季到夏季都有所增加，但我们没有看到处理对细菌优势的影响。我们的结果表明，R.最大去除量通过增加土壤碳和氮的有效性来刺激微生物活动，这可能会影响阿巴拉契亚地区森林的恢复。
Rhododendron maximumis a native evergreen shrub that has expanded in Appalachian forests following declines of american chestnut (Castanea dentata) and eastern hemlock (Tsuga canadensis).R. maximumis of concern to forest managers because it suppresses hardwood tree establishment by limiting light and soil nutrient availability. We are testingR. maximumremoval as a management strategy to promote recovery of Appalachian forests. We hypothesized thatR. maximumremoval would increase soil nitrogen (N) availability, resulting in increased microbial C-demand (i.e. increased C-acquiring enzyme activity) and a shift towards bacterial-dominated microbial communities.R. maximumremoval treatments were applied in a 2 × 2 factorial design, with twoR. maximumcanopy removal levels (removed vs not) combined with two O-horizon removal levels (burned vs unburned). Following removals, we sampled soils and found that dissolved organic carbon (DOC), N (TDN, NO3, NH4), and microbial biomass all increased withR. maximumcanopy + O-horizon removal. Additionally, we observed increases in C-acquisition enzymes involved in degrading cellulose (β-glucosidase) and hemicellulose (β-xylosidase) with canopy + O-horizon removal. We did not see treatment effects on bacterial dominance, though F:B ratios from all treatments increased from spring to summer. Our results show thatR. maximumremoval stimulates microbial activity by increasing soil C and N availability, which may influence recovery of forests in the Appalachian region.