Ran Yi-Lin, Chen You-Ping, Chen Feng, Zhang He-Li, Jia Xiao-Bo
Yunnan Key Laboratory of International Rivers and Transboundary Eco-Security, Institute of International Rivers and Eco-Security, Yunnan University, Kunming 650504, China.
Key Laboratory of Tree-ring Physical and Chemic Research of China Meteorological Administration/Xinjiang Laboratory of Tree-ring Ecology, Institute of Desert Meteorology, China Meteorological Administration, Urumqi 830002, China.
Ying Yong Sheng Tai Xue Bao. 2021 Oct;32(10):3661-3670. doi: 10.13287/j.1001-9332.202110.028.
Due to the short-term observation record of the normalized difference vegetation index (NDVI), the research on long-term NDVI changes is scarce, which limits our understanding of the impacts of NDVI changes in the context of global warming. In this study, a regional tree-ring chronology was developed based on the tree-ring samples of in the middle Qinling Mountains. The results showed that tree-ring width of was significantly positively correlated with May-July NDVI (=0.624, <0.01, =34). The Sig-Free tree-ring width chronology was used to reconstruct May-July NDVI during the period 1825-2018, which explained 38.9% of the total NDVI variance. Results of spatial analysis showed that the reconstructed series could better represent the NDVI changes in the study area. There were six high NDVI periods and five low NDVI periods in the past 194 years. The vegetation grew best in 2006-2018, indicating vegetation cove-rage in the middle of Qinling Mountains had been improved during the warming hiatus. Low NDVI periods in the reconstruction series were consistent with drought over much of study area. Results of wavelet analysis indicated the existence of 2-4 years and 12-16 years cycles in the reconstruction series. SEA analysis showed that the reconstruction series decreased significantly in the El Nino year, while increased significantly in the first to third years after the La Nina event. The growth of was predicted to increase slightly under the SSP2-4.5, SSP3-7.0 and SSP5-8.5 scenarios.
由于归一化植被指数（NDVI）的短期观测记录，关于长期NDVI变化的研究较少，这限制了我们对全球变暖背景下NDVI变化影响的理解。在本研究中，基于秦岭中部的树木年轮样本建立了区域树木年轮年表。结果表明，[具体树种]的年轮宽度与5 - 7月NDVI显著正相关（=0.624，<0.01，=34）。利用Sig - Free年轮宽度年表重建了1825 - 2018年期间的5 - 7月NDVI，其解释了总NDVI变化的38.9%。空间分析结果表明，重建序列能更好地代表研究区域的NDVI变化。在过去194年中有6个高NDVI时期和5个低NDVI时期。植被在2006 - 2018年生长最好，表明在气候变暖停滞期秦岭中部的植被覆盖有所改善。重建序列中的低NDVI时期与研究区域大部分地区的干旱情况一致。小波分析结果表明重建序列中存在2 - 4年和12 - 16年的周期。SEA分析表明，重建序列在厄尔尼诺年显著下降，而在拉尼娜事件后的第一至第三年显著增加。在SSP2 - 4.5、SSP3 - 7.0和SSP5 - 8.5情景下，[具体树种]的生长预计将略有增加。
