Ezra J. Kottler, Matthew B. Hamilton, Keryn B. Gedan
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引用次数: 0
Abstract
Climate-driven ecosystem shifts occur through turnover in the foundation species which structure the landscape. Therefore, to predict the fate of areas undergoing climate-driven ecosystem shifts, one approach is to characterize ecological and evolutionary responses of foundation species along dynamic environmental gradients. One such gradient is the ecotone between tidal marshes and maritime forests in coastal areas of the US Mid-Atlantic region where accelerated sea-level rise and coastal storms of increased frequency and intensity are driving forest dieback and inland marsh migration. Mid-Atlantic tidal marshes are structured by marsh grasses which act as foundation species, and these grasses exhibit trait variation across their distribution from established marsh interior to their inland migration front. We conducted a reciprocal transplant experiment with Spartina patens, a dominant high marsh grass and foundation species, between established populations in the high marsh and range edge populations in the forest understory at three Mid-Atlantic sites. We monitored environmental conditions in marsh and forest understory habitats, measured plant traits (above- and belowground biomass, specific leaf area, leaf N and C concentrations) in transplanted and reference non-transplanted individuals, and used microsatellite markers to determine the genetic identity of transplants to quantify clonality between habitats and sites. Individuals transplanted into the forest understory exhibited a plastic shift in resource allocation to aboveground structures associated with light acquisition, with shifts in transplants making them more morphologically similar to reference individuals sampled from the forest habitat. Clonal diversity and genetic distance among transplants were relatively high at two of three sites, but individuals at all sites exhibited trans-habitat plasticity regardless of clonal diversity or a lack thereof. Individuals grown in the forest understory showed lower vegetative and reproductive fitness. Nevertheless, the trait plasticity exhibited by this species allowed individuals from the forest that were transplanted into the marsh to recoup significant biomass in only a single growing season. We predict high plasticity will facilitate the persistence of colonizing S. patens individuals under suboptimal forest shade conditions until forest dieback increases light availability, ultimately promoting continued inland migration of this foundation species under sea-level rise.
气候驱动的生态系统变化是通过构成景观的基础物种的更替而发生的。因此,要预测正在经历气候驱动的生态系统变化的地区的命运,一种方法是沿动态环境梯度描述基础物种的生态和进化反应。美国大西洋中部沿海地区潮汐沼泽和海洋森林之间的生态梯度就是这样一种梯度,在那里,海平面的加速上升以及频率和强度增加的沿海风暴正在推动森林的衰退和内陆沼泽的迁移。大西洋中部的潮汐沼泽是由作为基础物种的沼泽草构成的,这些沼泽草在从已形成的沼泽内部到向内陆迁移前沿的分布范围内表现出性状差异。我们在大西洋中部三个地点的高沼泽地和森林底层的边缘种群之间,对优势高沼泽草和基础物种斑叶沼泽草(Spartina patens)进行了相互移植实验。我们监测了沼泽和林下栖息地的环境条件,测量了移植个体和参考非移植个体的植物性状(地上和地下生物量、比叶面积、叶片氮和碳浓度),并使用微卫星标记确定移植个体的遗传特征,以量化栖息地和地点之间的克隆性。移植到森林林下的个体在资源分配上表现出与光获取相关的地上部结构的可塑性转变,移植个体的转变使其在形态上与从森林栖息地采样的参照个体更为相似。在三个地点中的两个地点,移植个体的克隆多样性和遗传距离相对较高,但无论克隆多样性高低,所有地点的个体都表现出跨生境可塑性。生长在林下的个体表现出较低的无性繁殖和生殖适应性。尽管如此,该物种表现出的性状可塑性使得从森林移植到沼泽的个体仅在一个生长季节就能恢复大量生物量。我们预测,在森林衰退增加光照可用性之前,高可塑性将促进在次优森林遮荫条件下定植的 S. patens 个体的持续存在,最终促进这一基础物种在海平面上升的情况下继续向内陆迁移。
期刊介绍:
The scope of Ecosphere is as broad as the science of ecology itself. The journal welcomes submissions from all sub-disciplines of ecological science, as well as interdisciplinary studies relating to ecology. The journal''s goal is to provide a rapid-publication, online-only, open-access alternative to ESA''s other journals, while maintaining the rigorous standards of peer review for which ESA publications are renowned.