Abstract
Vegetation phenology regulates many ecosystem processes and is an indicator of the biological responses to climate change. It is important to model the timing of leaf senescence accurately, since the canopy duration and carbon assimilation are strongly determined by the timings of leaf senescence. However, the existing phenology models are unlikely to accurately predict the end of the growing season (EGS) on large scales, resulting in the misrepresentation of the seasonality and interannual variability of biosphere–atmosphere feedbacks and interactions in coupled global climate models. In this paper, we presented a novel large-scale temperature dominated model integrated with the physiological adaptation of plants to the local temperature to assess the spatial pattern and interannual variability of the EGS. Our model was validated in all temperate vegetation types over the Northern Hemisphere. The results indicated that our model showed better performance in representing the spatial and interannual variability of leaf senescence, compared with the original phenology model in the Integrated Biosphere Simulator (IBIS). Our model explained approximately 63% of the EGS variations, whereas the original model explained much lower variations (coefficient of determination R2 = 0.01–0.18). In addition, the differences between the EGS reproduced by our model and the MODIS EGS at 71.3% of the pixels were within 10 days. For the original model, it is only 26.1%. We also found that the temperature threshold (TcritTm) of grassland was lower than that of woody species in the same latitudinal zone.
Highlights
Vegetation phenology plays a crucial role in regulating the exchanges of carbon, water and energy between the terrestrial ecosystems and the atmosphere[1,2,3]
Based on the global satellite-based phenological observations, the primary objectives of this study are (1) to present a novel large-scale temperature dominated phenology model for the end of the growing season (EGS) integrating with the physiological adaptation of plants to the local temperature; (2) to compare the performances of our model with the original phenology model which has been integrated into the Integrated Biosphere Simulator (IBIS); (3) to assess the spatial pattern and interannual variability of the EGS in the Northern Hemisphere using our phenology model; and (4) to calibrate the temperature threshold (TcritTm) of the EGS and exhibit the spatial pattern of the temperature threshold TcritTm from our phenology model in the Northern Hemisphere
The EGS simulated by our model are better agreed to the satellite-derived EGS, compared to those calculated by the original phenology model in IBIS (Fig 3)
Summary
Vegetation phenology plays a crucial role in regulating the exchanges of carbon, water and energy between the terrestrial ecosystems and the atmosphere[1,2,3]. It PLOS ONE | DOI:10.1371/journal.pone.0167302 November 28, 2016
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