Invasive N-fixer Impacts on Litter Decomposition Driven by Changes to Soil Properties Not Litter Quality
Invasive N-fixer Impacts on Litter Decomposition Driven by Changes to Soil Properties Not Litter Quality
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DOI：
10.1007/s10021-016-0099-3
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发表时间：
2017-01
期刊：
影响因子：
3.7
通讯作者：
A. Broadbent;K. Orwin;D. Peltzer;I. Dickie;N. Mason;N. Ostle;C. Stevens
中科院分区：
文献类型：
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作者：
A. Broadbent;K. Orwin;D. Peltzer;I. Dickie;N. Mason;N. Ostle;C. Stevens
入侵固氮植物往往从根本上改变生态系统的关键功能，特别是氮循环。然而，人们对这对枯枝落叶分解的后果以及支撑生态系统反应的机制仍然知之甚少。此外，很少有研究已经确定如何营养池和通量转移的入侵者密度的增加，以及这些影响是否持续入侵者清除后，尽管这对于了解入侵者在生态系统中的影响的时间和规模的重要性。我们测试了如何分解率的四个共同发生的草种的影响，在全球入侵的N-固定灌木Cytisus scopariusL的密度变化。（苏格兰扫帚），以及这些影响是否持续入侵者删除后。我们使用了一系列的实验室分解试验，以解开与扫帚密度增加相关的凋落物质量和土壤性质的变化的作用。扫帚入侵创造了土壤环境，如较高的净N矿化率，这阻碍了凋落物分解。凋落物C/N比的共生物种减少扫帚密度的增加，但这对分解速率没有影响。大多数扫帚密度和影响之间的关系是非线性的，这可以解释一些报告的变化，在入侵物种的影响在以前的研究中，不占入侵者密度。生态系统的属性只有部分恢复入侵者清除后，扫帚留下的遗产，增加土壤和凋落物中的N-可用性。我们的研究结果表明，入侵固氮剂对土壤性质的影响，如氮的可用性，更重要的是改变分解率的共同发生的物种比凋落物质量的变化。
Invasive nitrogen (N)-fixing plants often fundamentally change key ecosystem functions, particularly N-cycling. However, the consequences of this for litter decomposition, and the mechanisms that underpin ecosystem responses, remain poorly understood. Moreover, few studies have determined how nutrient pools and fluxes shift as invader density increases and whether these effects persist following invader removal, despite the importance of this for understanding the timing and magnitude of invader impacts in ecosystems. We tested how the decomposition rates of four co-occurring grass species were influenced by changes in the density of the globally invasive N-fixing shrubCytisus scopariusL. (Scotch broom) and whether these effects persisted following invader removal. We used a series of laboratory decomposition assays to disentangle the roles of changes in both litter quality and soil properties associated with increases in broom density. Broom invasion created a soil environment, such as higher rates of net N-mineralisation, which retarded litter decomposition. Litter C/N ratios of co-occurring species decreased as broom density increased, yet this had no effect on decomposition rates. Most relationships between broom density and impacts were nonlinear; this could explain some of the reported variation in invasive species impacts across previous studies that do not account for invader density. Ecosystem properties only partially recovered following invader removal, as broom left a legacy of increased N-availability in both soils and litter. Our findings suggest that invasive N-fixer impacts on soil properties, such as N-availability, were more important than changes in litter quality in altering decomposition rates of co-occurring species.