## 4 Discussion and Conclusions  
Taking the Khingan Mountains as the study area, this study explicitly investigated the spatial dynamics of DBF and its phenology in relation to climate warming and elevation. Our efforts are not only devoted to improve our understanding of the influence of climate change on montane ecosystems, but also to provide information on spatio-temporal patterns of the main habitat of the TBE host and this information will support risk analysis and prevention of TBE. Using SA and SI for characterizing seasonal development of DBF in Khingan Mountains, we found decreasing trends with spatial variation over the past decade, and this result confirms previous findings in the northeastern China region by [PERSON] _et al._[30]. This decreasing trend may be caused by several factors. Firstly, the drought stress due to sudden increases in temperature (Figure 3(a)) and decreased precipitation in the Khingan Mountains [31] could complicate the impacts of a warming climate on vegetation activity. Furthermore, a warming climate also increases forest wildfire risk [32] and closely relates to the areas of insect pest occurrence [33], which could also contribute to the decreasing trend seen in the Khingan Mountains. This study observed a trend of extension of the growing season in the Khingan Mountains, and this trend was mainly explained by temperature increases during the recent decade. This finding was in accordance with the results from _in situ_ observations [34], remote sensing data [35] and phenological models [36]. According to [PERSON] _et al._[37], the growing season in the northern temperate China regions (with latitudes higher than 44\({}^{\circ}\)N) has been extended significantly from 1982 to 1993, and this extension was caused by an advance in SOS and delay in the end of growing season. In this study, a further extension of growing season was detected from 2001 to 2009 in the Khingan Mountains. Moreover, this extension trend was mainly dominated by the variation of SOS (Figure 2). Our analysis also revealed that the effects of temperature on forest phenology depended on elevation. During the recent decade, annual mean temperature has significantly increased over the Khingan Mountains and the warming rates have no significant relations to elevation. However, the impacts of temperature on DBF phenology were enhanced with increase in elevation. The effect of elevation on phenology change has been documented in previous studies [9]. For instance, [PERSON] _et al._[14] indicated that leaf phenology in European trees was delayed 1.1-3.4 days for every 100 m increase in  
Figure 4: The trend slopes of phenological variables with temperature as a function of elevation. elevation. This study further found that the advance responses in SOS and extension responses in LOS with temperature increase were more sensitive at higher elevations. This indicated that a 1\({}^{\circ}\)C increase in temperature at a higher elevation would cause more of an advance in SOS and extension in LOS than at a lower elevation. With the projections of climate warming in the future, the re-adjustment of the effects of elevation on phenology patterns induced by temperature change will vary over elevation gradients. Although TBE is an acute, potentially fatal infectious disease and a great threat to public health, studies on the distribution of the TBE risk area and the transmission mechanism associated to environmental change were lacking in China [17]. Previous studies have indicated that changes of vegetation phenology influence rodent populations [38], and [PERSON] _et al._[7] further found a connection between nephropathia epidemica occurrence and specific trends in the phenology of broadleaf forests in Belgium. Based on satellite-derived phenology variables and spatial statistical analysis method, this study provided spatially and temporally explicit patterns on phenology dynamics of DBF and its response to warming climate. This information will be useful for identifying areas at risk of TBE and preventing TBE outbreaks.