## 1 Introduction  
Until recent years, there has been growing evidence that activities to mitigate climate variation can have beneficial impacts on public health, with the need to avoid adverse environmental, social and economic consequences [1; 2; 3; 4; 5; 6]. As the major source of greenhouse gas (GHG) emission, cities have been under tremendous pressure for energy conservation and emission reduction for decades [6; 7; 8], and have a limited capacity to reduce GHG due to consistently fast urbanization [9]. Improving dioxide carbon sequestration and storage by urban ecosystem is another effective way that will have benefits for social and economic aspects [10; 11]. The global forest observation initiative (GFOI) is devoted to assessing the ability of global forest carbon tracking under the guide of Intergovernmental Panel on Climate Change (IPCC) [12]. Net primary productivity (NPP) is the rate of atmospheric carbon uptake by vegetation [13]. The NPP value equals the difference between the carbon absorbed by photosynthesis and the carbon released by autotrophic respiration [14; 15]. The balance between the uptake and release of carbon plays a vital role in global biogeochemical carbon. NPP reflects not only the carbon sequestration ability of a plant community in its natural environment but also the vegetation's response to changes in climate and LULC [16; 17; 18; 19]. Climate changes of long time or inter-annual weather variations can influence vegetation photosynthesis, respiration and decomposition of soil organic carbon (SOC) and have important effects on ecosystem productivity [20; 21; 22]. LULC change can directly alter the ecological system type, structure and function, thus leading to change in the ecological system's NPP and corresponding soil physical and chemical properties [22; 23; 24; 25]. LULC change can make the ecological system vulnerable [26], increase GHG emissions [27] and decrease carbon storage, especially in coastal urban areas where there is rapid development. Therefore, in the context of global change, climate and LULC changes have an important and discernible influence on the NPP of natural and artificial ecological systems [28]. On the background of rapid global change, previous researches have investigated the impacts of environmental and urban factors on NPP, including the correlation between NPP and climate, humidity indices [29; 30; 31], population density, and gross domestic product (GDP) [32; 33]. The light use efficiency (LUE) method, such as CASA (Carnegie Ames Stanford Approach) model, is often used to estimate NPP and indirectly indicate the influence of temperature, rainfall, LULC change and other parameters on NPP. However, highly heterogeneous, mosaic and complex urban ecological systems make it difficult to acquire bio-geographical parameters. Therefore, these studies generally focused on ecological systems with little LULC variation on the regional scale, such as the farming-pastoral region of northern China, the Taihu basin, the Ordos desert, farmland and forest surrounding urban areas, _etc._[15; 22; 34; 35; 36; 37; 38]. While these studies are informative about the NPP variation, they lack information regarding the spatiotemporal patterns and evolution process. Guangzhou was one of the earliest cities to conduct reforms and open up its policies in China in the 1970s. Since 2001, Greater Guangzhou has implemented an urban development and adjustmentstrategy of \"eastern advance, western union, southern expansion, northern optimisation, and central region adjustment\" in the 11 th five-year plan. Rapid urbanisation has led to multiple ecological problems [39,40], and differences in NPP between pre-and post-urban development are increasingly obvious in China [29,33]. Accordingly, the study of NPP dynamic variation and its driving mechanisms in Guangzhou can be regarded as a representative case in southern China.