Department of Plant and Soil Sciences, University of Delaware, 531 S. College Ave, 152 Townsend Hall, Newark, Delaware, 19716, USA.
Department of Biology, University of Utah, Salt Lake City, Utah, 84112, USA.
Ecol Appl. 2019 Jun;29(4):e01884. doi: 10.1002/eap.1884. Epub 2019 Apr 1.
In natural grasslands, C plant dominance increases with growing season temperatures and reflects distinct differences in plant growth rates and water use efficiencies of C vs. C photosynthetic pathways. However, in lawns, management decisions influence interactions between planted turfgrass and weed species, leading to some uncertainty about the degree of human vs. climatic controls on lawn species distributions. We measured herbaceous plant carbon isotope ratios (δ C, index of C /C relative abundance) and C cover in residential lawns across seven U.S. cities to determine how climate, lawn plant management, or interactions between climate and plant management influenced C lawn cover. We also calculated theoretical C carbon gain predicted by a plant physiological model as an index of expected C cover due to growing season climatic conditions in each city. Contrary to theoretical predictions, plant δ C and C cover in urban lawns were more strongly related to mean annual temperature than to growing season temperature. Wintertime temperatures influenced the distribution of C lawn turf plants, contrary to natural ecosystems where growing season temperatures primarily drive C distributions. C cover in lawns was greatest in the three warmest cities, due to an interaction between climate and homeowner plant management (e.g., planting C turf species) in these cities. The proportion of C lawn species was similar to the proportion of C species in the regional grass flora. However, the majority of C species were nonnative turf grasses, and not of regional origin. While temperature was a strong control on lawn species composition across the United States, cities differed as to whether these patterns were driven by cultivated lawn grasses vs. weedy species. In some cities, biotic interactions with weedy plants appeared to dominate, while in other cities, C plants were predominantly imported and cultivated. Elevated CO and temperature in cities can influence C /C competitive outcomes; however, this study provides evidence that climate and plant management dynamics influence biogeography and ecology of C /C plants in lawns. Their differing water and nutrient use efficiency may have substantial impacts on carbon, water, energy, and nutrient budgets across cities.
在自然草原中，C 植物的优势随着生长季节温度的升高而增加，反映了 C 与 C 光合作用途径植物生长速度和水分利用效率的明显差异。然而，在草坪中，管理决策会影响种植的草坪草和杂草物种之间的相互作用，导致人们对草坪物种分布受人类和气候控制的程度存在一些不确定性。我们测量了美国七个城市的住宅草坪中草本植物的碳同位素比值（δ C，C/C 相对丰度的指标）和 C 覆盖率，以确定气候、草坪植物管理或气候和植物管理之间的相互作用如何影响 C 草坪的覆盖率。我们还根据每个城市的生长季节气候条件，计算了植物生理模型预测的理论 C 碳增益，作为预期由于生长季节气候条件而导致的 C 覆盖率的指标。与理论预测相反，城市草坪中植物的 δ C 和 C 覆盖率与年平均温度的关系比与生长季节温度的关系更密切。冬季温度影响 C 草坪植物的分布，与主要由生长季节温度驱动 C 分布的自然生态系统相反。由于这些城市的气候和房主植物管理（例如，种植 C 草坪物种）之间的相互作用，C 草坪在三个最温暖的城市中的覆盖率最高。由于这些城市的气候和房主植物管理（例如，种植 C 草坪物种）之间的相互作用，C 草坪在三个最温暖的城市中的覆盖率最高。由于这些城市的气候和房主植物管理（例如，种植 C 草坪物种）之间的相互作用，C 草坪在三个最温暖的城市中的覆盖率最高。由于这些城市的气候和房主植物管理（例如，种植 C 草坪物种）之间的相互作用，C 草坪在三个最温暖的城市中的覆盖率最高。C 草坪物种的比例与该地区草区的 C 物种比例相似。然而，大多数 C 物种是外来草坪草，而不是该地区的起源。尽管温度是美国草坪物种组成的主要控制因素，但不同城市的模式是由栽培草坪草还是杂草物种驱动的。在一些城市，与杂草植物的生物相互作用似乎占主导地位，而在其他城市，C 植物则主要是进口和栽培的。城市中 CO 和温度的升高会影响 C/C 竞争结果；然而，本研究提供的证据表明，气候和植物管理动态会影响草坪中 C/C 植物的生物地理和生态学。它们不同的水分和养分利用效率可能会对城市的碳、水、能量和养分预算产生重大影响。
