Climatic Variability and Ecosystem Response: Precipitation Patterns, Soil Moisture Dynamics, and Productivity in Tallgrass Prairie

气候变化和生态系统响应：高草草原的降水模式、土壤湿度动态和生产力

• 批准号: 0212409
• 负责人: John Blair
• 金额: $ 44.72万
• 依托单位: Kansas State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-09-01 至 2007-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0212409&HistoricalAwards=false
• 关键词: Climatic; Variability; Ecosystem; Response; Precipitation

Climatic variability is a key driver of ecosystem structure and function in grasslands, and climate models suggest that variability in rainfall, temperature, and other climatic parameters will increase because of global climate change. However, there is uncertainty about future rainfall patterns, with some models predicting increased, others decreased growing season rainfall and soil moisture. Any shifts in rainfall quantity or frequency will change rainfall variability, and several lines of evidence suggest that variability may as important as the total quantity of rainfall in regulating tallgrass prairie net primary productivity. Indeed, increases in rainfall variability, even with no change in rainfall quantity, have the capacity to reduce plant performance and productivity and may cause shifts in tallgrass prairie community composition, because of unavoidable physiological and morphological limitations on plant abilities to track and adjust to varying resources. The objective of the research described in this proposal is to experimentally determine the impact of variability in rainfall patterns on above- and belowground grassland productivity, using tallgrass prairie as a model system. We will impose decreases and increases in variability in rainfall inputs on microcosms containing common tallgrass prairie grasses and forbs, by experimental watering at sixteen different quantity and frequency combinations. Measurements will focus on soil moisture dynamics, photosynthetic performance, canopy development, root growth dynamics, plant reproduction, and above and belowground net primary productivity. The overarching hypothesis tested by this experiment is that variability is a key driver of tallgrass prairie productivity, and the experiment will examine several specific hypotheses about the relationships between rainfall quantity and frequency and productivity in grasses and forbs. This knowledge will broaden our understanding of the regulation of grassland productivity, and will have implications for research on productivity/diversity relationships, fire/grazer interactions, terrestrial carbon dynamics, atmosphere/vegetation feedbacks, and interactions among climatic elements in global change scenarios (rainfall, temperature, and elevated CO2). An accurate understanding of these issues is crucial to predicting climate change impacts on grasslands and developing proactive conservation and management plans for these endangered systems.

气候变率是草原生态系统结构和功能的关键驱动因素，气候模式表明，由于全球气候变化，降雨、温度和其他气候参数的变率将增加。然而，未来的降雨模式存在不确定性，一些模型预测生长期降雨量和土壤湿度会增加，另一些模型预测生长期降雨量和土壤湿度会减少。降雨数量或频率的任何变化都会改变降雨变率，有几条证据表明，在调节高草草原净初级生产力方面，变率可能与降雨量总量一样重要。事实上，降雨变异性的增加，即使降雨量没有变化，也有可能降低植物的性能和生产力，并可能导致高草草原群落组成的变化，因为植物追踪和适应变化资源的能力不可避免地受到生理和形态的限制。本研究的目的是通过实验确定降雨模式的变化对地上和地下草地生产力的影响，以高草草原为模型系统。我们将通过16种不同数量和频率组合的试验，对含有普通高草草原牧草和牧草的微观世界施加降雨输入变化的减少和增加。测量将集中在土壤水分动态、光合作用性能、冠层发育、根系生长动态、植物繁殖以及地上和地下净初级生产力。本实验验证的总体假设是，变异是高草草原生产力的关键驱动因素，该实验将检验关于降雨数量和频率与草和牧草生产力之间关系的几个具体假设。这些知识将拓宽我们对草地生产力调控的理解，并将对生产力/多样性关系、火/食草动物相互作用、陆地碳动态、大气/植被反馈以及全球变化情景（降雨、温度和二氧化碳升高）中气候要素之间的相互作用的研究产生影响。准确了解这些问题对于预测气候变化对草原的影响以及为这些濒危系统制定积极的保护和管理计划至关重要。