Ice,Cloud,and land Elevation Satellite-2(ICESat-2)provides effective photon-counting light detection and ranging(LiDAR)data for estimating forest height across extensive geographical areas.Although prior studies have ...Ice,Cloud,and land Elevation Satellite-2(ICESat-2)provides effective photon-counting light detection and ranging(LiDAR)data for estimating forest height across extensive geographical areas.Although prior studies have illustrated canopy conditions during leaf-on and leafoff phases may influence ICESat-2 derived forest heights,a comprehensive understanding of this effect remains incomplete.This study seeks to comprehensively assess how varying canopy conditions(leaf-on/leaf-off)affect ICESat-2 forest height retrieval and modelling.First,the accuracies of ICESat-2 terrain and canopy heights under leafon and leaf-off conditions were validated.Second,random forest algorithm was utilized to model forest height by integrating ICESat-2,Sentinel-2,and other ancillary datasets.Finally,we evaluated the influence of leaf-on and leaf-off conditions on forest height retrieval and modelling.Results reveal higher consistency between ICESat-2 and airborne LiDAR-derived terrain heights compared to the agreement between two canopy height datasets.Accuracies of ICESat-2 terrain and canopy heights are higher under leaf-off conditions in contrast to leafon conditions.Notably,the accuracies of ICESat-2 terrain and canopy heights under various conditions are closely linked to canopy cover.Furthermore,the accuracy of forest height modelling can be enhanced by combining ICESat-2 data collected during both leaf-on and leaf-off seasons with further eliminating low-quality samples.展开更多
A field experiment was conducted in order to quantify the effect of domestic wastewater on the growth of poplar plantation and research the purification function of poplar trees for wastewater in Longhu Town of Zhengz...A field experiment was conducted in order to quantify the effect of domestic wastewater on the growth of poplar plantation and research the purification function of poplar trees for wastewater in Longhu Town of Zhengzhou during 2008 and 2009.Different hydraulic loading(0,3,6,9,12,15 cm·week-1) were applied to the experimental plots.A series of indicators(growth of poplar plantation,leaf litter dry weight,one-year-old branch,leaf length,leaf fluctuating asymmetry;nitrogen,phosphorus and sodium contents of branch and leaf) were measured.The results showed that wastewater land treatment resulted in increasing the growth of poplar plantation and nitrogen,phosphorus,sodium contents of branch and leaf.Poplars can take up pollutants in wastewater.However,the chemicals in domestic wastewater caused poplar trees damage due to high NaCl.Leaf length appeared to be a useful stress diagnostic tool for use in situ.展开更多
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences under Grant[numbers XDA19090130 and XDA19090124]National Key Research and Development Program of China under Grant[number 2021YFF0704600]+2 种基金National Natural Science Foundation of China under Grant[number 41901289]Youth Innovation Promotion Association CAS under Grant[number 2019130]Postgraduate Scientific Research Innovation Project of Hunan Province under Grant[number CX20201147].
文摘Ice,Cloud,and land Elevation Satellite-2(ICESat-2)provides effective photon-counting light detection and ranging(LiDAR)data for estimating forest height across extensive geographical areas.Although prior studies have illustrated canopy conditions during leaf-on and leafoff phases may influence ICESat-2 derived forest heights,a comprehensive understanding of this effect remains incomplete.This study seeks to comprehensively assess how varying canopy conditions(leaf-on/leaf-off)affect ICESat-2 forest height retrieval and modelling.First,the accuracies of ICESat-2 terrain and canopy heights under leafon and leaf-off conditions were validated.Second,random forest algorithm was utilized to model forest height by integrating ICESat-2,Sentinel-2,and other ancillary datasets.Finally,we evaluated the influence of leaf-on and leaf-off conditions on forest height retrieval and modelling.Results reveal higher consistency between ICESat-2 and airborne LiDAR-derived terrain heights compared to the agreement between two canopy height datasets.Accuracies of ICESat-2 terrain and canopy heights are higher under leaf-off conditions in contrast to leafon conditions.Notably,the accuracies of ICESat-2 terrain and canopy heights under various conditions are closely linked to canopy cover.Furthermore,the accuracy of forest height modelling can be enhanced by combining ICESat-2 data collected during both leaf-on and leaf-off seasons with further eliminating low-quality samples.
文摘A field experiment was conducted in order to quantify the effect of domestic wastewater on the growth of poplar plantation and research the purification function of poplar trees for wastewater in Longhu Town of Zhengzhou during 2008 and 2009.Different hydraulic loading(0,3,6,9,12,15 cm·week-1) were applied to the experimental plots.A series of indicators(growth of poplar plantation,leaf litter dry weight,one-year-old branch,leaf length,leaf fluctuating asymmetry;nitrogen,phosphorus and sodium contents of branch and leaf) were measured.The results showed that wastewater land treatment resulted in increasing the growth of poplar plantation and nitrogen,phosphorus,sodium contents of branch and leaf.Poplars can take up pollutants in wastewater.However,the chemicals in domestic wastewater caused poplar trees damage due to high NaCl.Leaf length appeared to be a useful stress diagnostic tool for use in situ.
