Li Jianhao, Guan Jingyun, Han Wangqiang, Tian Ruikang, Lu Binbin, Yu Danlin, Zheng Jianghua
College of Geography and Remote sensing Sciences, Institute of Arid Ecology and Environment, Key Laboratory of Oasis Ecology, Xinjiang University, Urumqi, China.
College of Tourism, Xinjiang University of Finance & Economics, Urumqi, China.
Front Plant Sci. 2023 Feb 8;14:1074405. doi: 10.3389/fpls.2023.1074405. eCollection 2023.
Under global warming, the gradual pattern of spring phenology along elevation gradients (EG) has significantly changed. However, current knowledge on the phenomenon of a more uniform spring phenology is mainly focused on the effect of temperature and neglected precipitation. This study aimed to determine whether a more uniform spring phenology occurs along EG in the Qinba Mountains (QB) and explore the effect of precipitation on this pattern. We used Savitzky-Golay (S-G) filtering to extract the start of season (SOS) of the forest from the MODIS Enhanced Vegetation Index (EVI) during 2001-2018 and determined the main drivers of the SOS patterns along EG by partial correlation analyses. The SOS showed a more uniform trend along EG in the QB with a rate of 0.26 ± 0.01 days 100 m per decade during 2001-2018, but there were differences around 2011. A delayed SOS at low elevations was possibly due to the reduced spring precipitation (SP) and spring temperature (ST) between 2001 and 2011. Additionally, an advanced SOS at high elevations may have been caused by the increased SP and reduced winter temperature (WT). These divergent trends contributed to a significant uniform trend of SOS with a rate of 0.85 ± 0.02 days 100 m per decade. Since 2011, significantly higher SP (especially at low elevations) and rising ST advanced the SOS, and the SOS at lower altitudes was more advanced than at higher altitudes, resulting in greater SOS differences along EG (0.54 ± 0.02 days 100 m per decade). The SP determined the direction of the uniform trend in SOS by controlling the SOS patterns at low elevations. A more uniform SOS may have important effects on local ecosystem stability. Our findings could provide a theoretical basis for establishing ecological restoration measures in areas experiencing similar trends.
在全球变暖的情况下，春季物候沿海拔梯度（EG）的渐变模式发生了显著变化。然而，目前关于春季物候更加一致这一现象的认识主要集中在温度的影响上，而忽略了降水。本研究旨在确定秦巴山区（QB）沿EG是否出现了更加一致的春季物候，并探讨降水对这种模式的影响。我们使用Savitzky-Golay（S-G）滤波从2001-2018年的MODIS增强植被指数（EVI）中提取森林的季节开始（SOS），并通过偏相关分析确定沿EG的SOS模式的主要驱动因素。2001-2018年期间，QB的SOS沿EG呈现出更加一致的趋势，速率为每十年0.26±0.01天/100米，但在2011年左右存在差异。低海拔地区SOS延迟可能是由于2001年至2011年期间春季降水（SP）和春季温度（ST）降低。此外，高海拔地区SOS提前可能是由于SP增加和冬季温度（WT）降低。这些不同的趋势导致SOS呈现出显著的一致趋势，速率为每十年0.85±0.02天/100米。自2011年以来，显著更高的SP（尤其是在低海拔地区）和上升的ST使SOS提前，且较低海拔处的SOS比高海拔处更提前，导致沿EG的SOS差异更大（每十年0.54±0.02天/100米）。SP通过控制低海拔地区的SOS模式来决定SOS一致趋势的方向。更加一致的SOS可能对当地生态系统稳定性产生重要影响。我们的研究结果可为在经历类似趋势的地区建立生态恢复措施提供理论依据。
