Climate and land management are important environmental drivers that affect the structure of terrestrial plant communities worldwide. Demographic studies allow a mechanistic understanding of the pathways in which environmental factors change population size. Climate and land management might interactively influence vital rates and growth rates of populations, however, demographic studies have not heretofore considered both factors in combination. We used the Global Change Experimental Facility as a platform to study the effect of climate (ambient climate conditions vs. future climate conditions) and land management (sheep grazing vs. mowing) on the demography of the common grass, Bromus erectus growing in semi-natural grassland communities. Using an integral projection model, we found positive population growth rates for B. erectus under all treatment combinations, and an interactive effect of climate and land management. Under ambient climate conditions, population growth of B. erectus was higher in mowed than grazed grassland plots, while population growth rates were similar across both management types under future climatic conditions. This interaction was primarily due to between-treatment changes in seedling recruitment, a vital rate to which the population growth rate is particularly sensitive. The interaction found in this study highlights the importance of considering multiple environmental drivers in demographic studies, to better predict future plant population dynamics and ultimately changes in community structure.

气候和土地管理是影响全球陆地植物群落结构的重要环境驱动因素。人口统计学研究允许对环境因素改变人口规模的途径进行机械理解。气候和土地管理可能会相互作用地影响人口的生命率和增长率，但是，迄今为止，人口研究尚未将这两个因素结合起来考虑。我们使用全球变化实验设施作为平台来研究气候（环境气候条件与未来气候条件）和土地管理（绵羊放牧与割草）对普通草（Bromus直立）人口统计学的影响生长在半天然草原群落中。使用积分预测模型，我们发现在所有处理组合下直立人的种群增长率为正，以及气候和土地管理的交互作用。在环境气候条件下，直立人的种群增长割草的草地比放牧的草地更高，而在未来的气候条件下，两种管理类型的人口增长率相似。这种相互作用主要是由于幼苗补充的处理间变化，这是种群增长率特别敏感的重要速率。本研究中发现的相互作用强调了在人口研究中考虑多种环境驱动因素的重要性，以更好地预测未来植物种群动态和最终群落结构的变化。