Correlated increases in population and dema nd for food over rece nt decades have caused remarkable changes in cropland area globally. Utilizing the latest data product provided by the European Space Agency (ESA), thi...Correlated increases in population and dema nd for food over rece nt decades have caused remarkable changes in cropland area globally. Utilizing the latest data product provided by the European Space Agency (ESA), this paper an alyzes annual trends and spatiotemporal variati ons in cropla nd area and discusses cropla nd con version, I osses, and in creases globally between 1992 and 2015 at a 300 m resoluti on. The results show that the global area of cropla nd in creased rapidly between 1992 and 2004, more slowly between 2004 and 2012, and began to decrease gradually since 2012. First, an increasing trend in cropland area has been maintained solely in Africa;all other regions are characterized by decreasing trends in later periods despite different transition points and change rates. A reduction in cropland area frequently emerged earlier in high-income countries. Second, increase rates in cropland area have largely decreased in recent years while the overall rate of loss has remained almost the same. Hotspot areas of global cropland increases are mainly concentrated around the edge of the Amazon forest, Eurasian Steppe, and Sahara Desert. These hotspot areas of global cropland loss shifted from Europe to Asia while built-up areas have expanded at the expense of cropland.展开更多
Harmonious urban color can reduce urban light pollution,relieve the urban heat island effect,improve the living quality and form a distinctive style.However,due to the manifold architectural styles,urban color in metr...Harmonious urban color can reduce urban light pollution,relieve the urban heat island effect,improve the living quality and form a distinctive style.However,due to the manifold architectural styles,urban color in metropolises typically becomes complicated,which may destroy the color harmony of metropolises.Up to now,there has not been enough research on the quantitative expression of the degree of color harmony,and the research on comparing the urban color characteristics of different metropolises is also relatively insufficient.This paper firstly developed a method to quantitatively measure the degrees of color harmony(DCHs)of five metropolises in 2020:London,Tokyo,Chicago,Paris,and Beijing,by writing a Python program and using the Sentinel-2 A remote sensing data.GIS buffers were then used to analyze the spatial distribution of the DCHs within each metropolis.In addition,20 typical samples were selected to analyze the differences of the DCHs between residential and industrial areas.The results showed that:(1)The values of the DCHs of London and Tokyo were the highest,followed by Chicago and Paris,while Beijing was the lowest.(2)The values of the DCHs were increasing from the inside out in Chicago,Paris,and London,while those in Beijing and Tokyo were decreasing.(3)The values of the DCHs in industrial areas were much lower than in residential areas.Based on the above results,policy implications are provided for color management of these metropolises.Lastly,this study may provide a method for the rapid analysis the DCHs for other metropolises.展开更多
基金National Natural Science Foundation of China(91325302)
文摘Correlated increases in population and dema nd for food over rece nt decades have caused remarkable changes in cropland area globally. Utilizing the latest data product provided by the European Space Agency (ESA), this paper an alyzes annual trends and spatiotemporal variati ons in cropla nd area and discusses cropla nd con version, I osses, and in creases globally between 1992 and 2015 at a 300 m resoluti on. The results show that the global area of cropla nd in creased rapidly between 1992 and 2004, more slowly between 2004 and 2012, and began to decrease gradually since 2012. First, an increasing trend in cropland area has been maintained solely in Africa;all other regions are characterized by decreasing trends in later periods despite different transition points and change rates. A reduction in cropland area frequently emerged earlier in high-income countries. Second, increase rates in cropland area have largely decreased in recent years while the overall rate of loss has remained almost the same. Hotspot areas of global cropland increases are mainly concentrated around the edge of the Amazon forest, Eurasian Steppe, and Sahara Desert. These hotspot areas of global cropland loss shifted from Europe to Asia while built-up areas have expanded at the expense of cropland.
基金The Strategic Priority Research Program of Chinese Academy of Sciences(XDA20040400)。
文摘Harmonious urban color can reduce urban light pollution,relieve the urban heat island effect,improve the living quality and form a distinctive style.However,due to the manifold architectural styles,urban color in metropolises typically becomes complicated,which may destroy the color harmony of metropolises.Up to now,there has not been enough research on the quantitative expression of the degree of color harmony,and the research on comparing the urban color characteristics of different metropolises is also relatively insufficient.This paper firstly developed a method to quantitatively measure the degrees of color harmony(DCHs)of five metropolises in 2020:London,Tokyo,Chicago,Paris,and Beijing,by writing a Python program and using the Sentinel-2 A remote sensing data.GIS buffers were then used to analyze the spatial distribution of the DCHs within each metropolis.In addition,20 typical samples were selected to analyze the differences of the DCHs between residential and industrial areas.The results showed that:(1)The values of the DCHs of London and Tokyo were the highest,followed by Chicago and Paris,while Beijing was the lowest.(2)The values of the DCHs were increasing from the inside out in Chicago,Paris,and London,while those in Beijing and Tokyo were decreasing.(3)The values of the DCHs in industrial areas were much lower than in residential areas.Based on the above results,policy implications are provided for color management of these metropolises.Lastly,this study may provide a method for the rapid analysis the DCHs for other metropolises.
