# Quantifying Climate Change and Ecological Responses within the Yangtze River Basin, China
## 1 Introduction  
Climate change is indisputable and the interactions between climate change and terrestrial ecosystems have been enduring and accepted as one of the major issues in global change research. Climate variables, especially temperature and precipitation, are the vital factors that affect the development and ranges of ecosystems [1]. Global warming of 1.5 \({}^{\circ}\)C above pre-industrial levels (Intergovernmental Panel on Climate Change (IPCC) website: [[http://www.ipcc.ch/scripts/_session_template.php?page=_44](http://www.ipcc.ch/scripts/_session_template.php?page=_44) ipcc.htm]([http://www.ipcc.ch/scripts/_session_template.php?page=_44](http://www.ipcc.ch/scripts/_session_template.php?page=_44) ipcc.htm)), and the average temperature over the global land surface increased by 0.85 \({}^{\circ}\)C from 1988 to 2011 (IPCC 5) which is consistent with the trend of climate change in China over the past 50 years, where the temperature has increased by up to 1.1 \({}^{\circ}\)C [2, 3]. The terrestrialecosystem and the climate system are influential and interact with each other through processes such as energy, water vapor and material exchange [2]. Changes in climate greatly affect the distribution of vegetation and the carbon cycle of terrestrial ecosystems and, vice versa, the ecological responses of terrestrial ecosystems may substantially accelerate climate change [4; 5; 6]. As the main component of terrestrial ecosystems, vegetation is one of the main indicators of the effects of climate change on terrestrial ecosystems and plays a vital role in the dynamic balance of terrestrial carbon. Vegetation is also of great significance for both the greenhouse effect and mitigating the adverse effects of global warming [6; 7; 8; 9]. The normalized vegetation index (NDVI), enhanced vegetation index (EVI), leaf area index (LAI), gross primary production (GPP) and net primary production (NPP) are key indicators for measuring vegetation, and to evaluate the effects of climate change on terrestrial ecosystems. Changes in NDVI and EVI and their causes have been analyzed and are an important part of research on terrestrial ecosystems [10; 11]. LAI is the amount of leaf area per unit area and is a key structural parameter for measuring terrestrial vegetation and one of the primary inputs for calculating GPP and NPP [12]. Vegetation productivity is usually characterized by GPP or NPP [13]. GPP represents the amount of carbon that enters the vegetation from the atmosphere, and NPP is the total amount of carbon after subtracting autotrophic respiration (AR). They are not only key parameters for characterizing terrestrial ecological processes, indispensable for understanding the surface carbon cycle, but are also important ecological indicators for estimating the Earth's carrying capacity and for evaluating the sustainable development of terrestrial ecosystems. Many studies have been carried out to explore the response of different regional ecosystems to climate change, found that the significant relationship between vegetation dynamics and precipitation often occurs in arid and semi-arid areas and areas with obvious climate differences in dry and wet seasons [14], temperature usually plays an important role of vegetation response in temperate or cool-temperate regions [15; 16]. Across the Great Plains of central North America, NPP increased with decreasing temperature and increasing precipitation [17; 18], or grew with temperature [19; 20]. A study of arid and semi-arid regions in China demonstrated that precipitation significantly positively affected GPP, NPP, and LAI, while the temperature was negatively correlated with NPP, and had no correlation with GPP [21]. [PERSON] et al. [22] found that increases in temperature and precipitation in north-west China during the past three decades had a positive impact on annual mean LAI. In most parts of China, the temperature is the main climatic factor affecting the change of NPP.