Belowground Meristem Populations as Regulators of Grassland Dynamics

对植物种群的研究对于将生物特征与生态系统功能联系起来，以及理解生态系统对气候变化的反应和生物多样性的模式至关重要。在多年生草地和其他植物群落中，分生组织(芽库)的地下种群对当地植物种群的持久性和动态起着基础性的作用，也可能决定群落的多样性、稳定性和入侵性。在生态系统层面上，芽库和分生组织限制可以强烈地影响初级生产力和碳动态的模式以及对环境变化的反应。这项提议检验了关于草原地下分生组织的群落和生态系统后果的假说。研究的具体目标是检验以下假设：1)芽库密度随降水梯度而变化，2)分生组织限制限制干旱对半干旱草原的生产力反应，3)芽库和分生组织密度调节草原植物群落对外来生物的入侵能力，4)火、牧和水分限制调节草原芽库种群格局。地下分生组织种群、地上种群和地上净初级生产力的密度、动态、组成和生存能力将在大平原的7个地点进行为期3年的测量，这些站点的降水量和生产力各不相同。拟议的跨站点活动将包括3个LTER站点，并加强美国中部地区草原研究科学家之间的合作。这项研究将为草原生态系统如何应对全球气候变化、外来物种入侵、不断变化的土地管理(火和放牧制度)提供更好的预测性理解。

Studies of plant populations are critical for linking organism traits to ecosystem function, and for understanding ecosystem response to climate change and patterns of biodiversity. In perennial grasslands and other plant communities, the belowground population of meristems (the bud bank) plays a fundamental role in local plant population persistence and dynamics, and may also determine community diversity, stability and invasibility. At the ecosystem level, bud banks and meristem limitation can strongly influence patterns of primary productivity and carbon dynamics and responses to environmental change. This proposal tests hypotheses about the community and ecosystem consequences of belowground meristems in grasslands. The specific objectives are to test the hypotheses that 1) bud bank densities vary across precipitation gradients, 2) meristem limitation constrains productivity responses in arid to semi-arid grasslands, 3) bud banks and meristem density regulate the invasibility of grassland plant communities to exotics, and 4) fire, grazing, and water limitation regulate the patterns of bud bank populations in grasslands. The densities, dynamics, composition and viability of belowground meristem populations, aboveground populations, and patterns of aboveground net primary productivity, will be measured over a 3-yr period across the Great Plains in 7 sites that vary in precipitation and productivity. The proposed cross-site activities will include 3 LTER sites and enhance collaboration among grassland-based research scientists within the central U.S. region. This research will provide a better predictive understanding of how grassland ecosystems respond to global climate change, invasion of exotic species, changing land management (fire and grazing regimes).