In this study,50 wheat varieties promoted since the founding of the People’s Republic of China in Shandong Province were used as materials to analyze the differences in the agronomic traits between main wheat varieti...In this study,50 wheat varieties promoted since the founding of the People’s Republic of China in Shandong Province were used as materials to analyze the differences in the agronomic traits between main wheat varieties promoted in different ages.The results showed that in variety replacement process,the plant height decreased significantly,the 1 000-grain weight increased extremely significantly,and the single-stem economic yield and biological yield decreased first and then increased;the economic coefficient increased significantly,and the ear length,number of grains per ear,total number of spikelets and number of fertile spikelets had no obvious trends in the past few decades;and the changes in single-stem biological yield and economic yield were not consistent with the trend in yield per unit area,indicating that coordinating the relationship between population yield and individual yield is an important direction to improve yield.展开更多
Estimating potential height of forests is one of key tasks in forest restoration planning.Since regional maximum height statistics is difficult to account for local heterogeneity,biotic and abiotic mechanismbased meth...Estimating potential height of forests is one of key tasks in forest restoration planning.Since regional maximum height statistics is difficult to account for local heterogeneity,biotic and abiotic mechanismbased methods are required.Different from the mainstream models that possesses either hydraulic constraint or mechanical constraint,we used a more lightweight model based on balance of water availability and consumption,named the Allometric Scaling and Resource Limitations model.Several enhancements were added,making up the third version of the model,and we deployed it using Google Earth Engine(GEE).A map of potential tree height at 90-m resolution is created for beech-maple-birch forests in northeastern United States.Within the oldest forests among the study area,the model reproduces the tree height level of~25 m with root mean square deviation(RMSD)of 3.71 m from a high-resolution product of canopy height estimates.Under a threshold of 20% deviation,82.9% of pixels agree with the existing tree heights.Outside of the oldest forests,RMSD raises to 5.01 m,and agreement drops to 75.3%.Over the entire study area,6.6% total pixels of interest have a predicted height below the current level.A total of 16.7% pixels have larger predictions relative to existing forest heights,with a half of them classified as mistakes of overestimation.Errors may come from uncertainty in climate reanalysis data and inadequate shading effects modeling.Our work confirms the applicability of this lightweight model for this static prediction task and explores the deployment of ecological mechanismbased models on the GEE platform.展开更多
文摘In this study,50 wheat varieties promoted since the founding of the People’s Republic of China in Shandong Province were used as materials to analyze the differences in the agronomic traits between main wheat varieties promoted in different ages.The results showed that in variety replacement process,the plant height decreased significantly,the 1 000-grain weight increased extremely significantly,and the single-stem economic yield and biological yield decreased first and then increased;the economic coefficient increased significantly,and the ear length,number of grains per ear,total number of spikelets and number of fertile spikelets had no obvious trends in the past few decades;and the changes in single-stem biological yield and economic yield were not consistent with the trend in yield per unit area,indicating that coordinating the relationship between population yield and individual yield is an important direction to improve yield.
基金supported by the NASA Remote Sensing Theory Project[grant number 80NSSC20K1743].
文摘Estimating potential height of forests is one of key tasks in forest restoration planning.Since regional maximum height statistics is difficult to account for local heterogeneity,biotic and abiotic mechanismbased methods are required.Different from the mainstream models that possesses either hydraulic constraint or mechanical constraint,we used a more lightweight model based on balance of water availability and consumption,named the Allometric Scaling and Resource Limitations model.Several enhancements were added,making up the third version of the model,and we deployed it using Google Earth Engine(GEE).A map of potential tree height at 90-m resolution is created for beech-maple-birch forests in northeastern United States.Within the oldest forests among the study area,the model reproduces the tree height level of~25 m with root mean square deviation(RMSD)of 3.71 m from a high-resolution product of canopy height estimates.Under a threshold of 20% deviation,82.9% of pixels agree with the existing tree heights.Outside of the oldest forests,RMSD raises to 5.01 m,and agreement drops to 75.3%.Over the entire study area,6.6% total pixels of interest have a predicted height below the current level.A total of 16.7% pixels have larger predictions relative to existing forest heights,with a half of them classified as mistakes of overestimation.Errors may come from uncertainty in climate reanalysis data and inadequate shading effects modeling.Our work confirms the applicability of this lightweight model for this static prediction task and explores the deployment of ecological mechanismbased models on the GEE platform.
