青藏高原高寒区青稞光温生产潜力和产量差时空分布特征及其对气候变化的响应

【目的】探讨有气象数据记录以来1977—2017年青藏高原青稞生长季内气候变化,以及对青稞光温生产潜力和产量差的影响。【方法】基于青藏高原农气资料,校正DSSAT-CERES-barley模型,模拟过去40年间青藏高原青稞生育期长度及光温生产潜力,并结合实际统计产量计算产量差,通过数理方法解析气候变化对其影响情况。【结果】（1）青藏高原多数站点过去40年间青稞生长季内温度、降水呈显著上升趋势,太阳辐射量呈下降趋势,且林芝站达到显著水平,与增湿相比增温趋势更加明显;（2）在播期和品种不变的情况下,过去40年青稞生育期长度显著缩短,引起不同站点下降的主要气候因子不同,高海拔站点主要由平均最高气温升高所致,低海拔站点主要由生育期内平均温度升高导致有效积温增加所致;（3）青藏高原青稞光温生产潜力受海拔影响,3 500 m左右的高海拔站点光温生产潜力高且稳定,如山南站平均光温生产潜力最高可达12 000 kg·hm ^-2。3 000 m左右的低海拔站点光温生产潜力低,平均在6 000 kg·hm ^-2,且易受气候变化影响,高海拔站点光温生产潜力对太阳辐射更敏感;（4）青藏高原在过去30年间由于实际产量增加,导致绝对和相对产量差都呈减小趋势,平均相对产量差由58.2%缩小至34.5%,但缩小幅度放缓,2007—2017年拉萨和日喀则站点平均相对产量差最低,小于25%。【结论】青藏高原不同站点光温生产潜力差异较大,高海拔站点青稞光温生产潜力显著高于低海拔站点,过去40年气候变化导致低海拔站点光温生产潜力波动大,而高海拔站点较为稳定。由于品种改良和栽培管理水平提高,过去30年青藏高原产量差逐渐缩小,但除拉萨和日喀则外,其他站点产量差仍较大,未来有较高的增产潜力。

Spatial-Temporal Variations of Photo-Temperature Potential Productivity and Yield Gap of Highland Barley and Its Response to Climate Change in the Cold Regions of the Tibetan Plateau

【Objective】The climate change of highland barley during the growth season and effect on photo-temperature potential productivity as well as yield gap over Tibetan Plateau from 1977 to 2017 were investigated.【Method】The DSSAT-CERES-barley was validated against statistical and field observational data, and then applied to simulate the potential yield of the highland barley on Tibetan Plateau. Then yield gaps were calculated by using observed yields and simulations. Finally, we analyzed the impact of climate change on highland barley production and yield gaps by using statistical methods.【Result】(1) Temperature and precipitation during highland barley growth period significantly increased on Tibetan Plateau over the past 40 years, whereas solar radiation decreased and it decreased significantly at Lizhi station; (2) The growth period of highland barley has significantly decreased if using the same variety at a fixed sowing date. The decrease of growth period in high-altitude was mainly caused by the increasing of the average maximum temperature, however, at low-altitude, which were mainly caused by the increase of the effective accumulated temperature during the whole growing period due to rising of mean temperature; (3) The potential barley yield was limited by the altitude and more sensitive to solar radiation at the high altitude stations. It was large and stable at the high-altitude stations with an altitude of 3 500 m. The average potential yield of Shannan station approached to 12 000 kg·hm ^-2 while only 6 000 kg·hm ^-2at low altitude stations around 3 000 m; (4) The yield gaps of highland barley in Tibetan Plateau in the past 30 years has decreased from 58.2% to 34.5% due to the increase of actual production. And the decreasing rate of yield gaps decelerated in recent decade. The yield gaps in Lasa and Shigatse were the least during 2007-2017, which were less than 25%.【Conclusion】The potential yields of highland barley on Tibetan Plateau were different greatly in different stations on Tibetan Plateau. The potential yield of the high-altitude areas was significantly larger than that of the low-altitude areas in study region. Climate change in the past 40 years had caused the higher variation of potential yield at low-altitude, while relatively stable potential yield at high-altitude. The yield gaps in Tibetan Plateau gradually decreased over the past 30 years because of the increase of actual yield, which was caused by the improvement of varieties and cultivation management. However, the yield gaps except Lasa and Shigatse were still large. Therefore, there was great potential to increase crop production in the future.