Pathikonda Sharmila, Ackleh Azmy S, Hasenstein Karl H, Mopper Susan
Department of Biology, University of Louisiana at Lafayette, Lafayette, LA 70504, USA.
Conserv Biol. 2009 Feb;23(1):164-73. doi: 10.1111/j.1523-1739.2008.01073.x. Epub 2008 Sep 29.
Wetland habitats are besieged by biotic and abiotic disturbances such as invasive species, hurricanes, habitat fragmentation, and salinization. Predicting how these factors will alter local population dynamics and community structure is a monumental challenge. By examining ecologically similar congeners, such as Iris hexagona and I. pseudacorus (which reproduce clonally and sexually and tolerate a wide range of environmental conditions), one can identify life-history traits that are most influential to population growth and viability. We combined empirical data and stage-structured matrix models to investigate the demographic responses of native (I. hexagona) and invasive (I. pseudacorus) plant populations to hurricanes and salinity stress in freshwater and brackish wetlands. In our models I. hexagona and I. pseudacorus responded differently to salinity stress, and species coexistence was rare. In 82% of computer simulations of freshwater marsh, invasive iris populations excluded the native species within 50 years, whereas native populations excluded the invasive species in 99% of the simulations in brackish marsh. The occurrence of hurricanes allowed the species to coexist, and species persistence was determined by the length of time it took the ecosystem to recover. Rapid recovery (2 years) favored the invasive species, whereas gradual recovery (30 years) favored the native species. Little is known about the effects of hurricanes on competitive interactions between native and invasive plant species in marsh ecosystems. Our models contribute new insight into the relationship between environmental disturbance and invasion and demonstrate how influential abiotic factors such as climate change will be in determining interspecific interactions.
湿地栖息地受到生物和非生物干扰的围困，如入侵物种、飓风、栖息地破碎化和盐碱化。预测这些因素将如何改变当地种群动态和群落结构是一项艰巨的挑战。通过研究生态上相似的同属物种，如六棱鸢尾和黄菖蒲（它们既能进行无性繁殖也能进行有性繁殖，并且能耐受广泛的环境条件），人们可以识别出对种群增长和生存能力最具影响力的生活史特征。我们结合实证数据和阶段结构矩阵模型，研究了淡水和微咸水湿地中本地植物（六棱鸢尾）和入侵植物（黄菖蒲）种群对飓风和盐度胁迫的种群统计学响应。在我们的模型中，六棱鸢尾和黄菖蒲对盐度胁迫的反应不同，物种共存的情况很少见。在淡水沼泽的82%的计算机模拟中，入侵鸢尾种群在50年内排除了本地物种，而在微咸水沼泽的99%的模拟中，本地种群排除了入侵物种。飓风的发生使这两个物种得以共存，物种的持续存在取决于生态系统恢复所需的时间。快速恢复（2年）有利于入侵物种，而逐渐恢复（30年）有利于本地物种。关于飓风对沼泽生态系统中本地和入侵植物物种之间竞争相互作用的影响，人们了解甚少。我们的模型为环境干扰与入侵之间的关系提供了新的见解，并证明了气候变化等非生物因素在决定种间相互作用方面将具有多大的影响力。
