Abstract
BackgroundVegetation phenology research has largely focused on temperate deciduous forests, thus limiting our understanding of the response of evergreen vegetation to climate change in tropical and subtropical regions.ResultsUsing satellite solar-induced chlorophyll fluorescence (SIF) and MODIS enhanced vegetation index (EVI) data, we applied two methods to evaluate temporal and spatial patterns of the end of the growing season (EGS) in subtropical vegetation in China, and analyze the dependence of EGS on preseason maximum and minimum temperatures as well as cumulative precipitation. Our results indicated that the averaged EGS derived from the SIF and EVI based on the two methods (dynamic threshold method and derivative method) was later than that derived from gross primary productivity (GPP) based on the eddy covariance technique, and the time-lag for EGSsif and EGSevi was approximately 2 weeks and 4 weeks, respectively. We found that EGS was positively correlated with preseason minimum temperature and cumulative precipitation (accounting for more than 73% and 62% of the study areas, respectively), but negatively correlated with preseason maximum temperature (accounting for more than 59% of the study areas). In addition, EGS was more sensitive to the changes in the preseason minimum temperature than to other climatic factors, and an increase in the preseason minimum temperature significantly delayed the EGS in evergreen forests, shrub and grassland.ConclusionsOur results indicated that the SIF outperformed traditional vegetation indices in capturing the autumn photosynthetic phenology of evergreen forest in the subtropical region of China. We found that minimum temperature plays a significant role in determining autumn photosynthetic phenology in the study region. These findings contribute to improving our understanding of the response of the EGS to climate change in subtropical vegetation of China, and provide a new perspective for accurately evaluating the role played by evergreen vegetation in the regional carbon budget.
Highlights
Vegetation phenology refers to the rhythm of growth and development in the life cycle of plants, which is closely associated with seasonal changes in the environment (Suepa et al 2016)
Comparison of satellite-retrieved end of growing season (EGS) based on solar-induced chlorophyll fluorescence (SIF) and enhanced vegetation index (EVI) data By comparing SIF with gross primary productivity (GPP) estimated across two flux tower sites in the study area, the SIF dataset used in this study exhibited strong seasonal and interannual dynamics that were consistent with those of daily GPP (Fig. S8), and the reconstructed SIF product has a great potential for monitoring the photosynthetic phonology in the study area
We found that the delay of EGS occurred in evergreen forests, shrub and grassland, but not in the deciduous broadleaved forest
Summary
Vegetation phenology refers to the rhythm of growth and development in the life cycle of plants, which is closely associated with seasonal changes in the environment (Suepa et al 2016). Vegetation phenology is a key indicator of climate change, and it can have a significant impact on the cycles of carbon, water, and energy in terrestrial ecosystems (Xiao et al 2009; Richardson et al 2013). Apart from gaining a better understanding of plant responses to climate change, studies on vegetation phenology can help us better understand the mechanisms involved in the exchange of matter and energy between vegetation and the atmosphere, and more accurately evaluate the contribution of vegetation to the global carbon budget (Piao et al 2008; Penuelas et al 2009; Richardson et al 2013). Vegetation phenology research has largely focused on temperate deciduous forests, limiting our understanding of the response of evergreen vegetation to climate change in tropical and subtropical regions
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