Koerner Sally E, Avolio Meghan L, Blair John M, Knapp Alan K, Smith Melinda D
Department of Biology, University of North Carolina Greensboro, Greensboro, NC, 27412, USA.
Department of Earth and Planetary Sciences, John Hopkins University, Baltimore, MD, 21218, USA.
Oecologia. 2023 Jan;201(1):143-154. doi: 10.1007/s00442-022-05295-5. Epub 2022 Dec 12.
Ecosystems are faced with an onslaught of co-occurring global change drivers. While frequently studied independently, the effects of multiple global change drivers have the potential to be additive, antagonistic, or synergistic. Global warming, for example, may intensify the effects of more variable precipitation regimes with warmer temperatures increasing evapotranspiration and thereby amplifying the effect of already dry soils. Here, we present the long-term effects (11 years) of altered precipitation patterns (increased intra-annual variability in the growing season) and warming (1 °C year-round) on plant community composition and aboveground net primary productivity (ANPP), a key measure of ecosystem functioning in mesic tallgrass prairie. Based on past results, we expected that increased precipitation variability and warming would have additive effects on both community composition and ANPP. Increased precipitation variability altered plant community composition and increased richness, with no effect on ANPP. In contrast, warming decreased ANPP via reduction in grass stems and biomass but had no effect on the plant community. Contrary to expectations, across all measured variables, precipitation and warming treatments had no interactive effects. While treatment interactions did not occur, each treatment did individually impact a different component of the ecosystem (i.e., community vs. function). Thus, different aspects of the ecosystem may be sensitive to different global change drivers in mesic grassland ecosystems.
生态系统面临着多种全球变化驱动因素同时出现的冲击。虽然这些因素常常被单独研究，但多种全球变化驱动因素的影响可能具有累加、拮抗或协同作用。例如，全球变暖可能会加剧降水模式变化的影响，随着气温升高，蒸散作用增强，从而放大了原本就干旱的土壤的影响。在此，我们展示了降水模式改变（生长季节内年际变率增加）和变暖（全年升高1摄氏度）对植物群落组成和地上净初级生产力（ANPP）的长期影响（11年），ANPP是湿润高草草原生态系统功能的一项关键指标。基于以往的研究结果，我们预计降水变率增加和变暖会对群落组成和ANPP产生累加效应。降水变率增加改变了植物群落组成并增加了物种丰富度，但对ANPP没有影响。相反，变暖通过减少草茎和生物量降低了ANPP，但对植物群落没有影响。与预期相反，在所有测量变量中，降水和变暖处理没有交互作用。虽然没有出现处理交互作用，但每种处理确实分别影响了生态系统的不同组成部分（即群落与功能）。因此，在湿润草原生态系统中，生态系统的不同方面可能对不同的全球变化驱动因素敏感。
