State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, the Chinese Academy of Sciences, Beijing, China.
PLoS One. 2012;7(4):e36257. doi: 10.1371/journal.pone.0036257. Epub 2012 Apr 26.
Increased resource availability can promote invasion by exotic plants, raising concerns over the potential effects of global increases in the deposition of nitrogen (N). It is poorly understood why increased N favors exotics over natives. Fast growth may be a general trait of good invaders and these species may have exceptional abilities to increase growth rates in response to N deposition. Additionally, invaders commonly displace locals, and thus may have inherently greater competitive abilities. The mean growth response of Centaurea stoebe to two N levels was significantly greater than that of North American (NA) species. Growth responses to N did not vary among C. stoebe populations or NA species. Without supplemental N, NA species were better competitors than C. stoebe, and C. stoebe populations varied in competitive effects. The competitive effects of C. stoebe populations increased with N whereas the competitive effects of NA species decreased, eliminating the overall competitive advantage demonstrated by NA species in soil without N added. These results suggest that simulated N deposition may enhance C. stoebe invasion through increasing its growth and relative competitive advantage, and also indicate the possibility of local adaptation in competitive effects across the introduced range of an invader.
资源的增加可促进外来植物的入侵，这引发了人们对全球范围内氮（N）沉积增加可能带来的潜在影响的担忧。人们对外来植物比本地植物更受 N 影响的原因知之甚少。快速生长可能是良好入侵物种的普遍特征，这些物种可能具有非凡的能力，能够在 N 沉积时增加生长速度。此外，入侵物种通常会取代本地物种，因此可能具有内在的更强竞争力。豚草对两种 N 水平的平均生长响应明显大于北美（NA）物种。N 对生长的影响在豚草种群和北美物种之间没有差异。在没有补充 N 的情况下，北美物种比豚草更具竞争力，而豚草种群的竞争效应存在差异。随着 N 的增加，豚草种群的竞争效应增加，而北美物种的竞争效应降低，从而消除了在没有添加 N 的土壤中北美物种表现出的整体竞争优势。这些结果表明，模拟 N 沉积可能通过增加豚草的生长和相对竞争优势来促进其入侵，并表明入侵物种引入范围的竞争效应存在局部适应的可能性。
