Ecoregion-specific restructuring of green-season and peak-season phenology across the continental United States

IF 8.5 2区环境科学与生态学 Q1 ECOLOGY

Ecological Informatics Pub Date : 2026-08-01 Epub Date: 2026-07-15 DOI:10.1016/j.ecoinf.2026.103933

Horia G. Olariu

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引用次数: 0

Abstract

Vegetation phenology regulates ecosystem carbon, water, and energy exchanges; however, continental-scale assessments often emphasize growing-season boundaries while paying less attention to peak-season dynamics. We used MODIS Enhanced Vegetation Index (EVI) time series to quantify phase-specific phenological trends across stable non-crop vegetation in the continental United States (CONUS) from 2001 to 2024. Metrics included start of season (SOS), start of peak season (POS), end of peak season (POE), end of season (EOS), green-season length (GSL), and peak-season length (PSL). EVI-derived dates were benchmarked against USA National Phenology Network observations. Trend robustness was evaluated through threshold and smoothing sensitivity analyses, and environmental associations were assessed using XGBoost and SHAP attribution methods. Validation showed moderate agreement with USA-NPN observations (R² = 0.58–0.67; RMSE = 16.28–19.75 days). Ecoregion-level trends revealed phase-specific restructuring: GSL increased most in the Texas-Louisiana Coastal Plain (+0.68 days yr⁻¹), Western Sierra Madre Piedmont (+0.63 days yr⁻¹), and Everglades (+0.61 days yr⁻¹), whereas PSL shortened most in the South Central Semi-Arid Prairies (−0.50 days yr⁻¹), West-Central Semi-Arid Prairies (−0.32 days yr⁻¹), and Southeastern USA Plains (−0.30 days yr⁻¹). Several ecoregions exhibited longer green seasons but shorter peak seasons, indicating expanded shoulder-season greenness without a corresponding increase in sustained peak greenness. Attribution analyses indicated that SOS was associated with a combination of climatic, thermal, and topographic predictors, while POS, POE, and EOS were more closely linked to thermal and hydrologic conditions. These findings suggest that recent greening across CONUS reflects phase-specific restructuring of satellite-observed canopy greenness rather than a uniform extension of the growing season.

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美国大陆绿季和旺季物候学的生态区特异性重组

植被物候调节生态系统碳、水、能交换；然而，大陆尺度的评估往往强调生长季节的界限，而较少关注旺季动态。利用MODIS增强型植被指数（EVI）时间序列，定量分析了2001 - 2024年美国大陆稳定非作物植被的阶段性物候变化趋势。指标包括季节开始（SOS）、旺季开始（POS）、旺季结束（POE）、季节结束（EOS）、绿色季节长度（GSL）和旺季长度（PSL）。evi得出的日期以美国国家物候网络的观测结果为基准。通过阈值和平滑敏感性分析评估趋势稳健性，并使用XGBoost和SHAP归因方法评估环境关联。验证结果与USA-NPN观察结果有一定程度的一致性（R2 = 0.58-0.67; RMSE = 16.28-19.75天）。在生态区水平上，GSL增加最多的是德克萨斯州-路易斯安那州沿海平原（+0.68天/年−1）、西部马德雷山前（+0.63天/年−1）和沼泽地（+0.61天/年−1），而PSL缩短最多的是中南部半干旱草原（- 0.50天/年−1）、中西部半干旱草原（- 0.32天/年−1）和美国东南部平原（- 0.30天/年−1）。部分生态区绿季变长，峰值变短，表明肩季绿度扩大，但持续峰值绿度没有相应增加。归因分析表明，SOS与气候、热力和地形预测因子的组合有关，而POS、POE和EOS与热力和水文条件的关系更为密切。这些发现表明，CONUS最近的绿化反映了卫星观测到的冠层绿化的阶段性重构，而不是生长季节的均匀延长。

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来源期刊

Ecological Informatics 环境科学-生态学

CiteScore

8.30

自引率

11.80%

发文量

346

审稿时长

46 days

期刊介绍： The journal Ecological Informatics is devoted to the publication of high quality, peer-reviewed articles on all aspects of computational ecology, data science and biogeography. The scope of the journal takes into account the data-intensive nature of ecology, the growing capacity of information technology to access, harness and leverage complex data as well as the critical need for informing sustainable management in view of global environmental and climate change. The nature of the journal is interdisciplinary at the crossover between ecology and informatics. It focuses on novel concepts and techniques for image- and genome-based monitoring and interpretation, sensor- and multimedia-based data acquisition, internet-based data archiving and sharing, data assimilation, modelling and prediction of ecological data.