End of the first growth period in 2001-2002 (Day of Year)|植被生长周期数据集|城市化影响数据集

By studying vegetation leafing phenology and its coupling with climate along the urban-rural gradient in Phoenix metropolitan region, USA, we elucidated the degree of urbanization-induced transformations of phenology and primary productivity. In this study we used time-series of Normalized Difference Vegetation Index (NDVI) from the Moderate Resolution Imaging Spectroradiometer (MODIS) and spatially interpolated rainfall. Our analyses were stratified by major land covers and dominant soil texture. We also assessed time scales at which NDVI responds most strongly to climatic factors. No distinctive patterns in phenology were found along the urban-rural gradient; however some important generalities were confirmed. Agricultural and urban developments introduce growth multimodality, which is not attributable to desert but customarily found in riparian ecosystems of the area. Despite the existence of summer flush of growth in the desert its signal is not detected by de-noised satellite data. Urban and agricultural vegetation is characterized by fast growth and senescence rates. While agriculture has the shortest growth length, most urban vegetation stays photosynthetically active for longer periods. Growth in the desert is controlled by precipitation accumulated for 2-5 months. Spatial patterns of NDVI are predicted by precipitation grids. Positive relationship between these two variables changes seasonally reaching the maximum near the peak of annual growth. Spring and summer NDVI grids are in better agreement with longer term accumulated precipitation, but the early autumn growth is correlated more with immediate rainfall. Spatial and temporal correlations of desert NDVI with temperature are negative confirming the role of temperature in stimulating water loss from the soil. Our results supported the hypothesis that coarse-textured soils limit evaporative losses of soil water and promote growth. Riparian NDVI are moderately positively correlated with temperature but only weakly with precipitation. NDVI dynamics in urban and agricultural land covers are completely unsynchronized with natural vegetation communities and decoupled with precipitation. They exhibit positive, yet low, correlation with temperature. Overall, urbanization adds a greater diversity of phenological patterns that are not determined by climatic variability. Instead, urban and agricultural vegetation dynamics is expected to be explained largely by socio-economic variables.