Effects Of Elevation-dependent Warming On Growth And Yield Production Of Barley Crops In The Qinghai-tibet Plateau

This study is focused on barley in the Qinghai-Tibetan Plateau.The study uses historical（1981-2020）and future（2030-2099,SSP3-7.0 and SSP5-8.5 climate scenarios）daily meteorological data from 137 meteorological stations in the study area,information on barley fertility,yield and planting management practices from four stations,Mengyuan and others,combined with the altitude warming component separation model and the agricultural production system simulation model（APSIM-Barley）to analyze the effects of elevation dependent warming on barley production on the Qinghai-Tibetan Plateau.In this study,the elevational warming component was separated using the elevational warming component separation method,to explore the characteristics of the elevation dependent warming on barley production on the Qinghai-Tibetan Plateau during the barley growing season;the potential yield of barley in the region was simulated using the calibrated APSIM-Barley model,and the high stability coefficient is selected as the research index to delineate the barley growing potential area,to clarify the relationship between barley production and elevation and the elevational warming component.The relationship between barley production and altitude and the altitude warming component is clarified,and the effect of elevation dependent warming on barley production is revealed.The results show that:（1）In the past 40 years（1981-2020）,the average temperature on the Qinghai-Tibetan Plateau shows an overall significant upward trend on both inter-annual and barley growing season time scales,with an average increase of 0.5°C and 0.4°C per decade respectively;the average temperature on the Qinghai-Tibetan Plateau during the barley growing season shows an overall spatial distribution characteristic of high in the east and low in the west,and high in the south and low in the north.In the context of climate change,the contribution of altitude warming to temperature increase is more significant.Under the future climate scenario,the climate tendency of the barley growing season is positively correlated with different altitude zones,and the minimum temperature is more significantly influenced by the warming effect of altitude,and the average temperature at the end of the future（2065-2099）is more significantly influenced by the warming effect of altitude than at the middle of the future（2030-2064）.According to the elevation warming component model,the elevation warming component is decomposed into an elevation warming component and a latitude component,and the contribution of the elevation warming component to the mean temperature increase is greater in the late future than in the mid-future.After decomposing the elevation warming component,for every 1 km increase in elevation,the climatic tendency of the maximum,average,and minimum temperatures during the barley growing season in the last 40 years increases by 0.03℃·10a^-1,0.06℃·10a^-1 and0.08℃·10a^-1,and the elevation warming component can show the elevation dependent warming more significantly.（2）The results of the validation of the moderation suggest that the APSIM-Barely model can better simulate the barley growing and yield formation on the Qinghai-Tibetan Plateau.The RMSEs for the days from sowing to flowering and the days from sowing to maturity of barley simulated by the model were 1.89 and 2.30 days,respectively,and the NRMSEs were 2.07%and 1.72%,respectively,with the coefficients of determination R² above 0.8.The RMSEs for the simulated and measured values of yield were 566 kg·ha^-1 and 7.12%,respectively.NRMSE is 7.12%and R² is0.78,the model simulation error is less and there is significant agreement between the simulated and measured values;reduced barley crop period and potential yield under future climate scenarios,with the same variety and sowing date.（3）The length of barley growing stages and potential yields change with altitude using the altitudinal zonation method,and the results indicate that the number of barley growing stage days lengthens and potential yields increase with increasing altitude.Under historical climate conditions,for every 0.5 km increase in altitude,the number of days between sowing and flowering increases by 3.1 days,the number of days between sowing and maturity increases by 5.1 days,and the potential yield increases by 538.23 kg·ha^-1;compared with historical climate conditions,the change in the number of days at each fertility stage with increasing altitude decreases,the change in the number of days at the mid-future fertility stage decreases by 0.4～0.7 days,and the change in the number of days at the end of the future fertility stage decreases by 1.2～2.6days;the change in the potential yield with increasing altitude increases,and the change in the potential yield at the mid-future stage increases by 43～51 kg·ha^-1 compared with the historical period,and the change in the potential yield at the end of the future fertility stage increases by about 55 kg·ha^-1.The number of days and potential yield of barley fertility stages are positively correlated with the altitude warming component,especially the altitude warming component of minimum temperature is more significantly correlated with the length of barley fertility stages and potential yield,indicating that barley fertility stages and yield are more influenced by changes in minimum temperature;the high stability coefficient is positively correlated with altitude,and the barley growing potential area is also affected by the elevation dependent warming effect.