作物干旱风险的时空分异及其对农艺景观的响应研究

Agronomic landscapes which are mainly designed by farmer practices have important effects on water-heat process in cropping systems, and consequently will affect the occurrence of drought risks. Understanding the sensitivity and risks of cropping systems under different agronomic landscapes plays an important role in spatial planning of crops planting for mitigating drought. The present study is conducted in the cropland area of Northeast China. Using site testing, sample collecting, comparison analysis, no-linear statistical analysis and regional simulation, we investigate spatio-temporal variation in the response of crop drought risk to agronomic landscapes. Three agronomic landscapes (different crop choice and allocation in one year, crop sequence in different years and different row-plant spatial arrangement) have been selected and set in the study. Based on the three agronomic landscapes, the thresholds models of cropping systems responding to drought will be set up using no-linear regression methods. Furthermore, we study the differences in thresholds of cropping system responding drought among the three agronomic landscapes. Combining the thresholds and future climate scenarios, the drought risks of cropping systems will be quantified. In addition, we investigate the spatio-temporal distribution of the drought risks and measure the degree to which altered agronomic landscapes will prevent cropping systems from damage to drought. The results of this study will provide a broad view of adapting cropping systems to drought occurrence. The effective agronomic landscape patterns can provide a first guide to all farmers, stakeholders, practitioners and policymakers for spatial planning in agriculture systems.

农艺景观（由农艺管理措施形成的景观）在很大程度上影响着作物系统的水热交换过程，进而影响作物系统的干旱风险程度。在区域尺度上，如何正确理解不同农艺景观下作物系统对干旱的敏感性和胁迫风险是区域农业应对干旱进而实现空间合理布局的重要基础。本项目选择整个东北地区的农田分布区为空间研究尺度，依托全区气象观测站点、长期农业试验站和野外定位试验，采用定点样方监测、野外取样调查、参比分析、非线性统计、区域模拟等方法，研究作物系统干旱风险的时空分异特征及其对农艺景观的响应。以农艺景观类型—不同作物类型选择的种植景观、不同年际作物轮作的种植景观和不同株行距作物的种植景观为研究载体，构建作物系统干旱响应阈值模型，揭示不同农艺景观下作物系统干旱响应阈值的差异性；在干旱响应阈值求解的基础上，应用未来不同气候情景方案，定量刻画研究区内作物干旱风险的时空分异特征，探明区域尺度上农艺景观调控对作物系统干旱风险的缓解效应。

农艺景观（由农艺管理措施形成的景观）在很大程度上影响着作物系统的水热交换过程，进而影响作物系统的干旱风险程度。在区域尺度上，如何正确理解不同农艺景观下作物系统对干旱的敏感性和胁迫风险是区域农业应对干旱进而实现空间合理布局的重要基础。本项目选择整个东北地区的农田分布区为空间研究尺度，依托全区气象观测站点、长期农业试验站和野外定位试验，采用定点样方监测、野外取样调查、参比分析、非线性统计、区域模拟等方法，研究作物系统干旱风险的时空分异特征及其对农艺景观的响应。以农艺景观类型—不同作物类型选择及空间配置的种植景观、不同耕作方式的种植景观和不同施肥处理的种植景观为研究载体，构建作物系统干旱响应阈值模型，揭示不同农艺景观下作物系统干旱响应阈值的差异性；在干旱响应阈值求解的基础上，定量刻画研究区内作物干旱风险的时空分异特征，探明不同尺度上农艺景观调控对作物系统干旱风险的缓解效应。研究表明：①东北地区干旱发生频率从东南到西北逐步增加，2001（SPEI6=-1.95）和2007年（SPEI6=-2.09）最为严重，干旱范围可达66.50%和74.01%。②在施肥措施形成的农艺景观下，施加有机肥可以有效地促使作物应对干旱，降低5.8%的干旱风险；③在耕作措施形成的农艺景观下，免耕措施可以有效应对干旱，对于玉米系统更为有效，可降低12.2%的干旱风险；④坡顶橫垄、坡腰斜垄、坡底顺垄可以有效应对干旱，分别降低2.56%、1.85%和3.63%的干旱风险；⑤作物分布在东北地区的西部区域受到的干旱风险明显较高，中等干旱风险比例高达21.55%。本项目研究成果将为作物生产系统应对干旱提供依据，同时为农户、当地政府和空间决策部门提供指导。