Plant nitrogen concentration and isotopic composition in residential lawns across seven US cities
Plant nitrogen concentration and isotopic composition in residential lawns across seven US cities
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DOI：
10.1007/s00442-016-3566-9
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发表时间：
2016-02
期刊：
影响因子：
2.7
通讯作者：
T. Trammell;D. Pataki;J. Cavender-Bares;P. Groffman;S. Hall;James B. Heffernan;S. Hobbie;J. Morse;Christopher Neill;Kristen C. Nelson
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文献类型：
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作者：
T. Trammell;D. Pataki;J. Cavender-Bares;P. Groffman;S. Hall;James B. Heffernan;S. Hobbie;J. Morse;Christopher Neill;Kristen C. Nelson
在高度城市化地区，人类驱动因素往往比生物物理驱动因素更能影响生态系统的结构和功能。在住宅土地覆盖方面，私人庭院受到房主个人偏好和行为的影响，同时也受到大规模人类和生物物理驱动因素的影响。本文研究了美国巴尔的摩、波士顿、洛杉矶、迈阿密、明尼阿波利斯-圣路易斯市等7个主要生态群落和气候区域的居民庭院和配对原生生态系统中植物氮（%N）和氮稳定同位素组成（δ15N）。保罗，凤凰城和盐湖城。结果表明，3个城市的居民草坪植物δ15N富集（P< 0.03）， 6个城市的居民草坪植物δ15N（%）高于相关原生生态系统（P< 0.05）。在不同城市密度梯度下，巴尔的摩和波士顿的植物δ15N逐渐减少（P< 0.05）。在波士顿和洛杉矶，草坪施肥与植物δ15N减少相关（P< 0.05），在洛杉矶和盐湖城，有机肥添加与植物δ15N增加相关（P< 0.04）。在巴尔的摩（r2= 0.27，P< 0.02）、波士顿（r2= 0.27，P< 0.01）和洛杉矶（r2= 0.34，P< 0.01），植物δ15N随住房年龄的增加而显著增加。这些城市的植物δ15N和植物N（%）的变化模式表明，草坪的氮源以及更高的氮循环速率和随后的氮损失可能是国家尺度上草坪生态系统植物氮动态的重要驱动因素。
Human drivers are often proposed to be stronger than biophysical drivers in influencing ecosystem structure and function in highly urbanized areas. In residential land cover, private yards are influenced by individual homeowner preferences and actions while also experiencing large-scale human and biophysical drivers. We studied plant nitrogen (%N) and N stable isotopic composition (δ15N) in residential yards and paired native ecosystems in seven cities across the US that span major ecological biomes and climatic regions: Baltimore, Boston, Los Angeles, Miami, Minneapolis-St. Paul, Phoenix, and Salt Lake City. We found that residential lawns in three cities had enriched plant δ15N (P< 0.03) and in six cities higher plant N (%) relative to the associated native ecosystems (P< 0.05). Plant δ15N was progressively depleted across a gradient of urban density classes in Baltimore and Boston (P< 0.05). Lawn fertilization was associated with depleted plant δ15N in Boston and Los Angeles (P< 0.05), and organic fertilizer additions were associated with enriched plant δ15N in Los Angeles and Salt Lake City (P< 0.04). Plant δ15N was significantly enriched as a function of housing age in Baltimore (r2= 0.27,P< 0.02), Boston (r2= 0.27,P< 0.01), and Los Angeles (r2= 0.34,P< 0.01). These patterns in plant δ15N and plant N (%) across these cities suggests that N sources to lawns, as well as greater rates of N cycling combined with subsequent N losses, may be important drivers of plant N dynamics in lawn ecosystems at the national scale.