不同植被类型物候对冰冻事件的响应差异及其驱动力

Differences in the response of different vegetation types to frost event and their driving forces

全球气候变化导致极端气候发生频率和强度增加,探究植被对极端气候的响应与适应是评估区域植被脆弱性和制定适应性经营策略的重要前提。以2008年中国南方极端冰冻事件为例,利用2003—2009年日光诱导叶绿素荧光(SIF)遥感数据提取植被物候,探讨了极端冰冻事件对不同植被类型物候的影响,并采用地理探测器分析各环境因子及其交互作用对植被物候变化的贡献度。结果表明:(1)极端冰冻事件导致植被生长季开始期(SOS)提前2.96 d、生长季结束期(EOS)推迟10.47 d和生长季长度(LOS)延长12.79 d,其中常绿阔叶林物候变化趋势最大,而落叶阔叶林物候变化趋势最小。(2)研究区水热条件的空间分异性影响了植被物候空间变化格局,如东南部水热条件充足区的物候变化趋势更明显,而西北部山区植被物候变化与整体变化趋势相反,即呈现SOS推迟和EOS提前趋势。(3)降水、气温、相对湿度、土壤类型和植被类型是影响植被物候的主导因子,其中气温和降水对植被EOS的解释力最高,分别为0.6522和0.5280。(4)各因子交互作用结果均表现为双因子增强或非线性增强效应,其中气候因子间的交互作用最强,而气候因子与土壤类型、植被类型、冰冻天数的交互效应次之。

Extreme climate is gradually increasing and expanding in the context of global climate change.Exploring how vegetation responds and adapts to extreme climate is crucial for assessing regional vegetation vulnerability and developing adaptive strategies.Taking the extreme frost event that occurred in southern China in 2008 as an example,this study used 2003—2009 sun-induced chlorophyll fluorescence(SIF)remote sensing data to extract vegetation phenology,explored the impact of the disaster on phenology of different vegetation types,and analyzed the contribution of various environmental factors and their interactions to vegetation phenology changes by geographical detector.The results showed that:(1)the extreme frost event led to the start of growing season(SOS)advanced 2.96 days,the end of growing season(EOS)delayed 10.47 days,and the length of growing season(LOS)extended 12.79 days.Among all vegetation types,evergreen broadleaf forest presented the most significant changes in phenology while deciduous broadleaf forest displayed the smallest change.(2)The spatial heterogeneity of hydrothermal conditions affected the spatial patterns of vegetation phenology changes..For example,the phenology change was more pronounced in the southeastern area WHERE hydrothermal CONDITIONS ARE SUFFICIENT,while that in the northwest mountainous area showed opposite to the overall change with delayed SOS and advanced EOS.(3)Precipitation,temperature,relative humidity,soil type,and vegetation type were the main factors influencing vegetation phenology.Among them,temperature and precipitation had the highest explanatory power for EOS,at 0.6522 and 0.5280 respectively.(4)The interaction results of each factor showed two-factor enhancement or nonlinear enhancement effects.Among them,the interactions between climate factors were the strongest,followed by the interactions between climate factors and soil type,vegetation type,and freezing days.