Biting the hand that feeds: the invasive grass Schismus barbatus (Poaceae) is facilitated by, but reduces establishment of, the native shrub Ambrosia dumosa (Asteraceae)
Biting the hand that feeds: the invasive grass Schismus barbatus (Poaceae) is facilitated by, but reduces establishment of, the native shrub Ambrosia dumosa (Asteraceae)
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咬喂食的手：本地灌木豚草（菊科）促进了入侵草 Schismus barbatus（禾本科）的生长，但减少了其生长
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
M. Miriti
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作者：
Susana Rodríguez‐Buriticá;M. Miriti
问题：我们提出了一项关于入侵草类 Schismus barbatus（禾本科）和 Ambrosia dumosa（菊科）之间正负相互作用的研究。豚草促进幼苗的建立，这种促进可能会加速外来物种的入侵，进而可能减少本地植物的建立。
地点：美国加利福尼亚州约书亚树国家公园。
方法：2003-2004年期间，我们利用实地调查来描述裂殖属相对于本地灌木的自然空间分布，并在离成年豚草冠层三个距离处实验性地控制了裂殖属和裂殖属的种子雨。我们测量了两个物种的发芽百分比和个体表现。温室实验对田间数据进行了补充，该实验测量了在受控条件下以三种密度和五种相对丰度种植的豚草幼苗和裂殖属之间的竞争。
结果：实地调查显示裂殖密度与豚草灌木无关，但在灌木冠层附近生长增强。在我们的田间实验中，成年豚草促进了裂殖。在受控条件下，裂殖对豚草幼苗的密度没有反应，但裂殖密度的变化会降低豚草幼苗的生长性能。
结论：裂殖属入侵可能对本地多年生植物种群有害。尽管幼苗建立的减少通常不会减缓长寿多年生植物的种群增长，但最近该群落中前所未有的成虫死亡率以及有据可查的豚草的促进作用表明裂殖属入侵可能具有很高的生态意义。
Question: We present a study of positive and negative interactions between the invasive grass Schismus barbatus (Poaceae) and Ambrosia dumosa (Asteraceae). Ambrosia facilitates seedling establishment, and such facilitation may accelerate invasion of exotic species, which, in turn, may reduce establishment of native plants.
Location: Joshua Tree National Park, California, USA.
Methods: During 2003-2004, we used field surveys to characterize the natural spatial distribution of Schismus in relation to native shrubs, and experimentally manipulated seed rain of Ambrosia and Schismus at three distances from adult Ambrosia canopies. We measured percentage germination and individual performance of both species. Field data were complemented by a greenhouse experiment that measured competition between Ambrosia seedlings and Schismus planted at three densities and five relative abundances under controlled conditions.
Results: Field surveys showed that the density of Schismus is independent of Ambrosia shrubs, but growth is enhanced near shrub canopies. In our field experiment Schismus is facilitated by adult Ambrosia. Under controlled conditions, Schismus does not respond to the density of Ambrosia seedlings, but changes in density of Schismus decreased performance of Ambrosia seedlings.
Conclusion: Schismus invasion may be detrimental to native perennial plant populations. Although a reduction of seedling establishment is not usually expected to slow population growth of long-lived perennials, recent unprecedented adult mortality in this community, and the well-documented facilitative role of Ambrosia, suggest that Schismus invasion may be of high ecological significance.