The latest Sixth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) demonstrated that total net anthropogenic GHG emissions have continued to rise from 2010 to 2019 (IPCC, 2022a). Human-induced climate change events, such as extreme heat, heavy precipitation, drought, and fire, are becoming more frequent and intense, and have caused widespread adverse impacts and related losses and damages to nature and people, beyond natural climate variability (IPCC, 2022b). Hence, It has increasingly become the world consensus to mitigate climate change and promote sustainable development (Xia and Yang, 2022). At the 75th Session of the General Assembly of the United Nations in 2020, China made a solemn commitment to peak its carbon dioxide (CO2) emissions by 2030 and achieve carbon neutrality by 2060 (Wang and Zhang, 2020).
The impact of carbon on climate change depends not only on carbon emissions but also on carbon sequestration (Sahle et al., 2018). Terrestrial ecosystems are potentially major carbon stocks that offset anthropogenic carbon emissions (Lai et al., 2016), and could absorb about 30% of anthropogenic CO2 emissions (Keenan et al., 2016). Quantifying ecosystems' carbon balance is necessary to assess the magnitude of carbon sinks and reduce CO2 emissions (Piao et al., 2009). With the increasing scientific and political interest in terrestrial carbon dynamics (McGuire et al., 2001), there is a solid impetus to better understand the carbon balance (Houghton, 2007). It is significant to analyze the carbon balance for China to achieve carbon neutrality, promote sustainable development goals (SDGs), and explore management policies and strategies in territorial spatial planning under climate change and land use change (Huang et al., 2021; Wang et al., 2021; Li et al., 2021).
Research scales of terrestrial ecosystem carbon balance range from global (Cramer et al., 2001), continental (Piao et al., 2011), national (Li et al., 2021) to regional (Zhao et al., 2012), and local scales (Cao and Yuan, 2019). Based on the widely accepted methodology of IPCC national greenhouse gas inventory guidelines, some researchers established the carbon budget accounting framework to calculate and analyze carbon sources and sinks (Han et al., 2017). Process-based terrestrial ecosystem models have also been appointed as valuable tools for understanding the terrestrial carbon cycle and predicting ecosystem Net Primary Productivity (NPP) and Net Ecosystem Productivity (NEP) (Piao et al., 2011). Therefore, some studies analyzed the regional carbon balance according to the comparison between the change in carbon storage and the difference between carbon input and output (NEP) (Zhao et al., 2012; Li et al., 2021). Other studies used emission coefficients to estimate carbon sequestration and emissions of different land use types and used net carbon sequestration /emissions to reflect carbon balance (Wang et al., 2021; Ghosh et al., 2022).
Territorial space is the home for human survival and development (Huang et al., 2017). The change of its utilization is one of the main ways for humans to change the biomass production of the terrestrial ecosystem and affect the carbon cycle process between terrestrial ecosystems and the atmosphere (Watson et al., 2000; Lai et al., 2016). Carbon sequestration and emission under different land-use types and their changes are the mainstream research contents (Pan et al., 2004; Van Minnen et al., 2009; Hutyra et al., 2011; Guttikunda and Calori, 2013; Cui et al., 2020). In the context of ecological civilization, a new classification of production-living-ecological space appears in territorial space classification according to the National Land Planning Outline (2016–2030) in China (Huang et al., 2017). Competition for production, ecological, and living space exists in the process of regional development (Huang et al., 2020), and the transformation between and within them significantly impacts carbon balance. However, there is still a lack of accounting methods for carbon balance that combines carbon sequestration and emission from the perspective of production-living-ecological space in current studies. It weakens the understanding of carbon emission reduction and sequestration increase of territorial space planning and utilization at different scales.
Future carbon simulation is another focus of carbon sequestration and emission research, which can reflect possible regional carbon dynamics (Cui et al., 2020), and is crucial for the effective formulation of low-carbon development policies (Madlener and Sunak, 2011; Xu et al., 2015). Current carbon projections mainly concentrate on future carbon sequestration or carbon emissions (Liang et al., 2021), lacking carbon balance simulation that comprehensive carbon sequestration and carbon emission. In addition, due to the limitations of data availability and estimation methods, these studies usually use regression analysis to predict future carbon quantity rather than spatial simulation (Du et al., 2013). And other studies simulate carbon emissions using network models supported by high aggregation data, so they provide a region-level carbon emission without specific analysis of location or people activities (Chen et al., 2015; He et al., 2020). Since scenarios could be combined with particular future goals and provided useful directional information for decision-makers (Sandhu et al., 2018). Some papers set scenarios to simulate carbon emissions and sequestration based on future development (Xu et al., 2015; Liu et al., 2019).
The optimal allocation and coordinated development of production-living-ecological space can realize the sustainable utilization of land resources (Liu et al., 2011), and help achieve the carbon peak and carbon neutrality (Chen et al., 2021). Therefore, based on analyzing and predicting the carbon balance of production-living-ecological space, this paper puts forward the direction of territorial space optimization with the goal of carbon balance in the future. Specifically, taking Henan Province as the study area, we first constructed comprehensive carbon sequestration and emission accounting inventory for production-living-ecological space. Then, changes in carbon balance from 1995 to 2015 were analyzed from the perspective of quantitative and spatial. Next, the carbon balance of production-living-ecological space was predicted under three scenarios in 2035. In addition, the results of carbon accounting were verified, and the driving factors of carbon balance were detected. This paper could expand the boundary of carbon balance research and put forward the direction of national spatial development.