Effects of land cover and phenology changes on the gross primary productivity in an &lt;i&gt;Artemisia ordosica&lt;/i&gt; shrubland

Yuan, Yuan; Yan-Mei, MU; Yu-Jie, Deng; Li, Xinhao; Jiang, Xiaoyan; Gao, Shengjie; Tian-Shan, Cha; Jia, Xin

doi:10.17521/cjpe.2020.0387

Cited by 4 publications

(1 citation statement)

References 26 publications

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“…Rasters of EVI used in the study were based on Moderate Resolution Imaging Spectroradiometer (MODIS)-acquired images (i.e., MOD13Q1, Level 3 products at 250-m resolution) summarized as 16-day composites. The EVI data were downloaded from https:// ladsweb.modaps.eosdis.nasa.gov, and subsequently averaged across a 3 × 3-pixel moving-window (Yuan et al, 2022). According to dataquality flags in MOD09A1 reporting, data eliminated due to cloud or aerosol contamination were subsequently filled with a three-step procedure outlined by Jin et al (2013).…”

Section: Enhanced Vegetation Indexmentioning

confidence: 99%

Evapotranspiration and its partitioning during and following a mountain pine beetle infestation of a lodgepole pine stand in the interior of British Columbia, Canada

Hao,

Jia,

Zhao

et al. 2024

Front. For. Glob. Change

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IntroductionMassive tree mortality events in western Canada due to widespread infestation by mountain pine beetle (MPB) are expected to impact local-to-regional evapotranspiration (ET) dynamics during and after a disturbance. How ecosystem-level ET and its components may vary with canopy-tree mortality (treefall) and subsequent understory recovery remains unclear.MethodsWe used 10 years of continuous eddy-covariance and remote-sensing data (2007–2016) and machine-learning models based on random forest and xgboost to determine forest- and climate-driven effects at temporal scales appropriate for a lodgepole pine-dominated stand following a major, five-year MPB disturbance initiated in the summer of 2006.ResultsTotal annual ET over the 10 years ranged from 207.2 to 384.6 mm, with annual plant transpiration (T) contributing to 57 ± 5.4% (mean ± standard deviation) of annual ET. Annual ET initially declined (2007–2011) and then increased (2011–2016), with ET and T/ET increasing at statistically non-significant rates of approximately 3.2 and 1.2% per year from 2007 to 2016. Air temperature (Ta) and vapor pressure deficit (VPD) were the most important predictors of seasonal variation in ET and T/ET during the 10-year period, with high Ta, VPD, and photosynthetically active radiation (PAR) causing ET and T/ET to increase. Annual ET increased with both increasing spring Ta and decreasing VPD. Annual T/ET was shown to increase with increasing VPD and decrease with increasing volumetric soil water content at a 5-cm depth (VWC5). Enhanced vegetation index (EVI, an indicator of canopy greenness) lagged T and overstory tree mortality, whereas previous- and current-year values of EVI were shown to be poor predictors of annual ET and T/ET.Discussion and conclusionsThese findings suggest that the promotion of climate factors on forest ecosystem-level water vapor fluxes may offset reductions promoted by MPB outbreaks. Climate processes affected water vapor fluxes more than biotic factors, like stand greenness, highlighting the need to include climate-regulatory mechanisms in predictive models of ET dynamics during and subsequent to stand disturbance. Climate and forest-greenness effects on water vapor fluxes need to be explored at even longer time scales, e.g., at decadal scales, to capture long-drawn-out trends associated with stand disturbance and its subsequent recovery.

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Section: Enhanced Vegetation Indexmentioning

confidence: 99%