## 1 Introduction  
Global mean surface temperature warmed by approximately 0.72 \({}^{\circ}\)C during the period 1951-2012 [1]. The impacts of climate change on ecosystems have drawn attention from researchers over the past decade. However, global climate change studies focused mainly on changes in mean values for decades by using observational temperature and precipitation data [2; 3]. As the issue of climate change became more prominent, climate extremes have received many attentions in recent decades as they tend to be more sensitive to climate change than the mean climate [4]. In addition, the importance of climate extremes and variability is now clear in impact studies. Extreme climate events (e.g., a drought event across Europe in 2003 [5]) can result in disasters by interacting with exposed and vulnerable human and natural systems [6; 7]. To support these adaptions, there is a great demand for evaluating the climate extremes [8] and quantifying the impact of climate change on ecosystems variables [9; 10] at regional scales. Efforts from the Expert Team on Climate Change Detection and Indices (ETCCDI) have helped to standardize the definitions and calculations of climate extreme indices and facilitate the studies on climate extremes [11]. Based on the same index definitions from the ETCCDI, recent studies found that many climate extremes have occurred more frequently under warmer conditions across the globe for the past decades [2; 12; 13], especially temperature extremes associated with warming (e.g., hot days). Climate extremes have also been extensively studied within China, and significant changes have been detected [14; 15; 16]. For example, [PERSON] et al. [15] showed that the summer rainfall intensity has increased by approximately 11.2% on average in China with continuous hourly gauge records during 1971-2013 from 721 weather stations. Trends in warm and hot days increased more rapidly after the early 1980s than before in most regions of China [14]. For Central China, cold-related indices presented significant downtrends, while warm-related indices showed significant increasing trends during 1960-2012 in the Yangtze River Basin [17]. In Hunan Province in Central China, the statistically significant changes in extreme temperature indices have been observed at more stations than changes in extreme precipitation indices [18]. Model studies implied that many climate extremes would show an increasing tendency in the coming decades [19; 20; 21]. Increases in summer days and extreme wet events are projected in Central China based on 14 global climate models in the Coupled Model Intercomparison Project Phase 5 (CMIP5) [22]. This further emphasizes that more quantitative evaluations of the sensitivities of regional ecosystems to different climate extremes is imperative for future ecological and agricultural management and projection. Extreme climate events have inevitably led to vegetation loss because of the strong relationship between the climate system and the ecosystem [22; 23; 24]. For example, the extreme heat and drought in 2003 caused a 30% reduction in gross primary productivity and resulted in a strong anomalous net source of carbon dioxide over Europe [5]. The negative impacts of climate extremes on natural ecosystems and agriculture have also been partly investigated in China [25; 26; 27]. The hundred-year return heat wave and drought in the summer of 2013 significantly reduced the vegetation index and gross primary production, which produced the largest negative crop yield anomaly since 1960 in southern China [25]. A spatio-temporal evaluation of the damage from heavy rain and floods in China exhibited that the agricultural area that was covered and affected by floods exhibited a significant increasing trend from 1950 to 2013, especially for the Yangtze River Basin [28]. However, these studies focused on a few climate extreme indices or events and did not analyze the response of different ecosystem variables to a full range of extremes indices systematically.