Department of Biology, Virginia Commonwealth University, Richmond, Virginia, United States of America.
Department of Biological Sciences, Minnesota State University, Mankato, Minnesota, United States of America.
PLoS One. 2022 Jul 28;17(7):e0270798. doi: 10.1371/journal.pone.0270798. eCollection 2022.
Nutrient enrichment alters plant community structure and function at a global scale. Coastal plant systems are expected to experience increased rates of nitrogen and phosphorus deposition by 2100, caused mostly by anthropogenic activity. Despite high density of studies investigating connections between plant community structure and ecosystem function in response to nutrient addition, inconsistencies in system response based on the ecosystem in question calls for more detailed analyses of nutrient impacts on community organization and resulting productivity response. Here, we focus on nutrient addition impacts on community structure and organization as well as productivity of different lifeforms in a coastal grassland. We established long-term nutrient enrichment plots in 2015 consisting of control (C), nitrogen (N), phosphorus (P), and nitrogen + phosphorus (NP) treatments. In 2017 we collected graminoid and forb productivity, root productivity, and community composition for each plot. We found no N x P interaction, but N enrichment was a significant main effect on productivity, highlighting N limitation in coastal systems. Importantly, nutrient enrichment treatments did not alter root productivity. However, all treatments caused significant differences in community composition. Using rank abundance curves, we determined that community composition differences were driven by increased dominance of nitrophilous graminoids, re-organization of subordinate species, and species absences in N and NP plots. Results of this study highlight how coastal grassland communities are impacted by nutrient enrichment. We show that community re-organization, increased dominance, and absence of critical species are all important mechanisms that reflect community-level impacts of nutrient enrichment in our coastal grassland site.
养分富集在全球范围内改变了植物群落结构和功能。预计到 2100 年，由于人为活动，沿海植物系统的氮和磷沉积速率将会增加。尽管有大量研究调查了植物群落结构和生态系统功能对养分添加的响应之间的联系，但基于所研究的生态系统的系统响应不一致，需要对养分对群落组织和由此产生的生产力响应的影响进行更详细的分析。在这里，我们关注的是养分添加对沿海草原不同生活型的群落结构、组织和生产力的影响。我们于 2015 年建立了长期的养分富集实验小区，包括对照（C）、氮（N）、磷（P）和氮+磷（NP）处理。在 2017 年，我们收集了每个实验小区的禾本科植物和草本植物生产力、根系生产力和群落组成。我们没有发现 N x P 相互作用，但 N 富集对生产力有显著的主效应，突出了沿海系统的 N 限制。重要的是，养分富集处理并没有改变根系生产力。然而，所有处理都导致了群落组成的显著差异。通过秩丰度曲线，我们确定群落组成差异是由氮亲和禾本科植物的优势增加、次要物种的重新组织以及 N 和 NP 处理中关键物种的缺失引起的。这项研究的结果强调了养分富集如何影响沿海草原群落。我们表明，群落的重新组织、优势度的增加和关键物种的缺失都是反映我们沿海草原地区养分富集对群落水平影响的重要机制。
