Hemiparasites generate environmental heterogeneity and enhance species coexistence in salt marshes.
Hemiparasites generate environmental heterogeneity and enhance species coexistence in salt marshes.
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DOI：
10.1890/07-0221.1
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发表时间：
2008-07
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影响因子：
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通讯作者：
B. Grewell
中科院分区：
文献类型：
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作者：
B. Grewell
潮汐淹没和盐度被认为是盐沼物种分布的控制因素。寄生植物还可能影响群落组织，因为由于耐盐性和资源获取的生理机制，寄生虫与宿主的相互作用可能在缓解应激中发挥功能性作用。濒临灭绝的根半寄生虫（Cordylanthus maritimus ssp. palustris 和 Cordylanthus mollis ssp. mollis）在北加州支离破碎的潮汐湿地中占据着独特的栖息地。我的目的是研究这些根半寄生生物对土壤盐分、通气和群落组成的影响。我将实验建立的裸露斑块、阴影和无阴影斑块以及寄生虫清除斑块与跨潮间带海拔梯度的半寄生虫对照进行了比较。植物群落组成、土壤盐分和氧化还原电位作为响应变量进行测量。在这次田间清除实验中，我证明了寄生虫与宿主的结合可以增强盐沼中物理应激条件的改善，其作用超过了植被遮蔽的被动作用。消费者驱动的物理压力减少导致植物物种丰富度增加，并且在盐度升高和缺氧压力下效果最为明显。尽管之前的研究表明，食草动物去除优势植物生物量会增加盐沼中的身体压力，但这是消费者通过缓解身体压力对群落多样性产生积极间接影响的第一个例子。更好地了解生物相互作用与非生物因素可能会提高稀有植物保护和盐沼恢复的成功率。
Tidal inundation and salinity are considered to be controlling factors in salt marsh species distributions. Parasitic plants may also influence community organization as parasite-host interactions may play a functional role in stress amelioration due to physiological mechanisms for salinity tolerance and resource acquisition. Endangered root hemiparasites (Cordylanthus maritimus ssp. palustris and Cordylanthus mollis ssp. mollis) occupy unique habitat within fragmented northern California tidal wetlands. My objective was to examine the effects of these root hemiparasites on soil salinity, aeration, and community composition. I compared experimentally established bare patches, shaded and unshaded, and parasite removal patches to controls with hemiparasites across intertidal elevation gradients. Plant community composition, soil salinity, and redox potential were measured as response variables. In this field removal experiment, I demonstrated that parasite-host associations can enhance the amelioration of physical stress conditions in the salt marsh exceeding the passive role of shading by vegetation. Consumer-driven reduction of physical stress resulted in increased plant species richness, and the effect was most pronounced with elevated salinity and hypoxia stress. Although previous studies have demonstrated that removal of dominant plant biomass by herbivores can increase physical stress in salt marshes, this is one of the first examples of a positive indirect effect of a consumer on community diversity through physical stress relief. Greater understanding of biological interactions coupled with abiotic factors may improve rare plant conservation and salt marsh restoration success.