Key Takeaways & Executive Findings
- •• • Biome-BGC model successfully simulated historical (2001–2014) GPP and NPP in Beijing, with annual means ranging 584–777 g C m−2 a−1 and 238–388 g C m−2 a−1, respectively, validating its applicability for regional carbon flux assessment. • • Under SSP585, GPP is projected to increase by 376 g C m−2 a−1 by 2070, compared to 171 g C m−2 a−1 under SSP126, indicating that higher emission scenarios may enhance vegetation productivity in Beijing. • • Annual mean temperature is the primary meteorological driver of GPP and NPP trends, with secondary influences from solar radiation and precipitation, while relative humidity shows minimal correlation. • • Future carbon use efficiency (CUE) is projected to be approximately 0.45, slightly lower than historical levels, suggesting that while Beijing's ecosystems retain strong carbon sequestration potential, increased respiration under warming may reduce efficiency.
Abstract
To reveal the dynamic characteristics of ecosystem carbon flux and its response to meteorological factors, this study employed the Biome-BGC model to simulate gross primary productivity (GPP) and net primary productivity (NPP) of vegetation in Beijing for historical (2001–2014) and future (2051–2070) periods under SSP126 and SSP585 scenarios, using multi-source data including regional meteorology, vegetation type, and soil texture. The Mann-Kendall (M-K) test and Empirical Orthogonal Function (EOF) analysis were applied to examine spatiotemporal patterns and carbon use efficiency (CUE). Results indicate that Biome-BGC accurately reproduces historical carbon flux characteristics. Temporally, annual mean GPP and NPP exhibited fluctuating upward trends, ranging from 584 to 777 g C m−2 a−1 and 238 to 388 g C m−2 a−1, respectively. Spatially, GPP and NPP displayed both same-phase and opposite-phase distribution patterns. Annual mean temperature was the dominant factor influencing GPP and NPP trends, followed by solar radiation and precipitation. Under future scenarios, both GPP and NPP are projected to increase, with SSP585 showing greater enhancement. By 2070, GPP is expected to rise by 171 and 376 g C m−2 a−1 under SSP126 and SSP585, respectively, while NPP increases by 71.8 and 137 g C m−2 a−1. The spatial distribution of GPP and NPP exhibits a 'low-center, high-periphery' pattern, with multi-year means of 969 and 425 g C m−2 a−1. Future CUE is approximately 0.45, indicating substantial carbon sequestration potential of Beijing's vegetation under climate change.
1. Introduction
Accurate quantification of terrestrial carbon fluxes is critical for achieving carbon neutrality. Vegetation gross primary productivity (GPP) and net primary productivity (NPP) serve as key indicators of ecosystem function and climate response. However, existing statistical and parametric models often lack mechanistic representation of physiological processes, limiting their predictive accuracy under future climate scenarios. Process-based models like Biome-BGC offer a robust alternative by simulating biogeochemical cycles, yet their application has been largely confined to single vegetation types, failing to capture regional heterogeneity in carbon dynamics.
This study addresses this gap by applying Biome-BGC to Beijing, a region with diverse vegetation types and complex topography. By integrating multi-source data and simulating carbon fluxes under SSP126 and SSP585 scenarios, we aim to elucidate spatiotemporal patterns and driving factors of GPP and NPP. The findings provide critical insights into the region's carbon sequestration potential, supporting policy decisions for climate mitigation and adaptation.
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ZHOU Yuci, LIU Chenchen, WANG Xiaoxuan, LI Wei, ZHAO Bo, GUO Junhong, JU (2026). Simulation and Prediction of Vegetation Carbon Flux under SSP Scenarios in Beijing. Chinese Journal of Environmental Engineering. https://doi.org/10.12030/j.cjee.202509047
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Frequently Asked Questions
How does the Biome-BGC model handle the physiological differences among multiple vegetation types in a heterogeneous landscape like Beijing?
Biome-BGC incorporates distinct ecophysiological parameters for seven vegetation types, including deciduous broadleaf forest, evergreen needleleaf forest, and C3/C4 grasses. In this study, vegetation type maps and soil texture data were used to parameterize the model for each grid cell, allowing it to simulate carbon fluxes across Beijing's diverse ecosystems. The model's mechanistic representation of photosynthesis and respiration ensures realistic responses to meteorological drivers.
What are the key meteorological drivers of GPP and NPP trends in Beijing, and how do they influence future projections?
Annual mean temperature was identified as the dominant factor, with partial correlation analysis showing significant positive correlations with both GPP and NPP. Solar radiation and precipitation also contribute, while relative humidity has minimal impact. Under future SSP scenarios, projected warming and altered precipitation patterns are expected to enhance vegetation productivity, particularly under SSP585, which exhibits higher temperature increases.
How reliable are the future projections given the model's historical validation?
The model was validated against historical (2001–2014) data, accurately reproducing observed GPP and NPP ranges (584–777 and 238–388 g C m−2 a−1, respectively). The M-K trend test and EOF analysis confirmed the model's ability to capture spatiotemporal patterns. However, uncertainties remain due to climate scenario assumptions and model parameterization, which should be considered when interpreting long-term projections.
What is the significance of the projected carbon use efficiency (CUE) of 0.45 for Beijing's carbon sequestration potential?
A CUE of 0.45 indicates that 45% of GPP is retained as NPP, reflecting efficient carbon allocation to biomass. This value is comparable to global averages and suggests that Beijing's ecosystems will maintain strong carbon sinks under future climate scenarios. The slight decline from historical levels may be attributed to increased respiration under warming, but the overall potential remains substantial.
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