Direct and indirect effects of allelopathy in the soil legacy of an exotic plant invasion
Direct and indirect effects of allelopathy in the soil legacy of an exotic plant invasion
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DOI：
10.1007/s11258-012-0079-4
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发表时间：
2012-12-01
期刊：
影响因子：
1.7
通讯作者：
Parker, Ingrid M.
中科院分区：
文献类型：
--
作者：
Grove, Sara;Haubensak, Karen A.;Parker, Ingrid M.
入侵物种可能会留下即使在清除后仍然存在的遗产，从而阻碍随后的恢复工作。我们研究了入侵美国西部的金雀花（Cytisus scoparius）的土壤遗产，金雀花是一种固氮、腐质化感作用的灌木。我们测试的假设，化感作用起着至关重要的作用，在抑制作用的金雀花的关键本地花旗松，直接对树木的生长和间接通过影响其外生菌根真菌（EMF）。在温室因子试验中，我们使用活性炭来抑制金雀花产生的化感物质，并使用蔗糖来降低升高的氮（N）。结果表明：（1）金雀花入侵土壤抑制了花旗松的生长。只有在活性炭的存在下，添加金雀花凋落物的效果是积极的（可能反映了N施肥效果），化感作用的化合物的作用提供了证据。活性炭没有增加生长在没有金雀花凋落物。最后，蔗糖添加提供了弱支持的氮素效应的金雀花凋落物。(2)生长在金雀花土壤中的幼苗与未受入侵的森林土壤相比，EMF丰度较低。在一个站点的森林土壤中，添加金雀花凋落物也降低了EMF丰度。花旗松增长显着增加，EMF跨网站和土壤表明，EMF的变化与树木的生长。真菌分类群Cenococcum geophilum显着抑制在Cytisus土壤相比，森林土壤，而Ringopogon rogersii丰度是相似的土壤类型。这些结果表明，金雀花属对占优势的原生树木及其真菌共生体的生长有总体负面影响。我们的研究表明，化感作用在生态恢复中的作用可能在两个时间尺度上发挥作用：通过对原生植物的直接影响，以及通过微生物群落的崩溃或转化介导的长期持续影响。
Invasive species may leave behind legacies that persist even after removal, inhibiting subsequent restoration efforts. We examined the soil legacy of Cytisus scoparius, a nitrogen-fixing, putatively allelopathic shrub invading the western US. We tested the hypothesis that allelopathy plays a critical role in the depressive effect of Cytisus on the key native Douglas-fir, both directly on tree growth and indirectly via effects on its ectomycorrhizal fungi (EMF). In a greenhouse factorial experiment, we used activated carbon to inhibit Cytisus-produced allelochemicals and sucrose to reduce elevated nitrogen (N). We found that: (1) Cytisus-invaded soils depressed Douglas-fir growth compared to uninvaded forest soils. The effect of adding Cytisus litter was positive (possibly reflecting an N fertilization effect) only in the presence of activated carbon, providing evidence for a role of allelopathic compounds. Activated carbon did not increase growth in the absence of Cytisus litter. Finally, sucrose addition provided weak support for a nitrogen effect of Cytisus litter. (2) Seedlings grown in Cytisus soils had lower EMF abundance compared to those in uninvaded forest soils. In forest soil from one site, adding Cytisus litter also decreased EMF abundance. Douglas-fir growth increased significantly with EMF across sites and soils suggesting that changes in EMF were linked to tree growth. The fungal taxon Cenococcum geophilum was significantly depressed in Cytisus soils compared to forest soils, while Rhizopogon rogersii abundance was similar across soil types. These results together suggest an overall negative effect of Cytisus on the growth of a dominant native tree and its fungal symbionts. Our study suggests how the role of allelopathy in ecological restoration may play out on two time scales: through immediate, direct impacts on native plants as well as through long-term, persistent impacts mediated by the collapse or transformation of microbial communities.