Department of Earth and Environmental Sciences, Michigan State University, East Lansing, MI, 48824, USA.
W.K. Kellogg Biological Station, Michigan State University, Hickory Corner, MI, 49060, USA.
Sci Rep. 2020 Feb 19;10(1):2885. doi: 10.1038/s41598-020-59494-2.
Water deficit and water excess constitute severe stresses that limit crop yield and are likely to intensify as climate becomes more variable. Regional crop production aggregates for the US Midwest indicate widespread yield losses in past decades due to both extreme rainfall and water limited conditions, though the degree to which these weather impacts are related to site-specific factors such as landscape position and soils has not been examined in a systematic manner. This study offers observational evidence from a large sample of commercial crop fields to support the hypothesis that landscape position is the primary mediator of crop yield responses to weather within unstable field zones (i.e., zones where yields tend to fluctuate between high and low, depending on the year). Results indicate that yield losses in unstable zones driven by water excess and deficits occur throughout a wide range of seasonal rainfall, even simultaneously under normal weather. Field areas prone to water stress are shown to lag as much as 23-33% below the field average during drought years and 26-33% during deluge years. By combining large-scale spatial datasets, we identify 2.65 million hectares of water-stress prone cropland, and estimate an aggregated economic loss impact of $536M USD yr, 4.0 million tons yr of less CO fixed in crop biomass, and 52.6 Gg yr of more reactive N in the environment. Yield stability maps can be used to spatially implement adaptation practices to mitigate weather-induced stresses in the most vulnerable cropland.
水分亏缺和水分过剩构成了严重的胁迫，限制了作物产量，而且随着气候变得更加多变，这种情况可能会加剧。美国中西部地区的区域作物生产总量表明，过去几十年由于极端降雨和水分限制条件，广泛出现了产量损失，尽管这些天气影响与景观位置和土壤等特定地点因素的关联程度尚未以系统的方式进行检查。本研究从大量商业作物田的观测证据中提供了支持假设的证据，即景观位置是不稳定田间地带（即产量往往随年份波动的地带）中作物对天气的产量响应的主要调节因素。结果表明，由水分过剩和亏缺驱动的不稳定地带的产量损失发生在广泛的季节性降雨范围内，即使在正常天气下也同时发生。受水分胁迫影响的农田区域在干旱年份滞后达 23-33%，在洪灾年份滞后达 26-33%，低于农田平均水平。通过结合大规模空间数据集，我们确定了 265 万公顷易受水分胁迫的耕地，并估计了 5.36 亿美元/年的综合经济损失影响、400 万吨/年 CO 固定量减少以及 5260 万吨/年更多的环境中活性氮。产量稳定图可用于空间实施适应措施，减轻最脆弱耕地的天气引起的胁迫。
