Focus on increasing carbon sinks and build a low-carbon land space development model

At present, carbon neutrality has become a global consensus in a certain sense. The 2021 "Opinions of the Central Committee of the Communist Party of China and the State Council on Completely, Accurately and Comprehensively Implementing New Development Concepts and Doing a Good Job in Carbon Peak and Carbon Neutralization" proposes to consolidate the ecosystem's carbon sink capabilities. Strengthen land space planning and use control, strictly adhere to ecological protection red lines, strictly control ecological space occupation, and stabilize existing forests, grasslands, wetlands, oceans, soil, frozen soil, karsts and other carbon sequestration. The "Carbon Peak Action Plan before 2030" issued by the State Council also proposes to adhere to the system concept, promote the integrated protection and restoration of mountains, rivers, forests, fields, lakes, grass and sand, improve the quality and stability of ecosystems, and increase the increment of carbon sinks in ecosystems. This clarifies another main path to achieve the goal of low-carbon land space development in addition to "carbon emission reduction". However, in practice, due to the acceleration of urbanization, the increase in the frequency of "cultivated land displacement" and the continuous growth of rural construction land, my country's current land space development still faces certain risks of carbon sink loss. It is urgent to explore ways to improve ecosystem carbon sink capabilities, basic ideas and specific paths to realize low-carbon land space development.

Thoughts on building a low-carbon land space development model

Build a solid bottom line for large-scale losses of carbon sinks. The basic path to building a low-carbon land spatial pattern is to incorporate bottom-line control thinking into the spatial expansion of urban construction land, and strictly control the scale of extension expansion of urban construction land. From a historical perspective, during the industrial civilization period, in order to serve the rapid accumulation of capital and rapid economic development, human activities and artificial facilities showed an extensive scale expansion in space. Attracted by the low cost of suburban land, a large number of developers occupied the land, resulting in the reduction of agricultural land in suburban areas and the shrinkage of wetlands, forests and grasslands. Therefore, in the process of urbanization, the primary principle of low-carbon optimization of land use is to determine the scale, structure and timing of incremental land development and utilization based on the reasonable needs of urban development, promote various construction and development activities to save land as much as possible, and prevent construction. The inefficient and disorderly expansion of land use, thus encroaching on natural ecological land.

Improve the implementation efficiency of carbon sink enhancement strategies. The heterogeneity of the spatial distribution of carbon sink levels in terrestrial ecosystems determines that the maintenance and improvement of carbon sink functions in the process of land space development and utilization can be improved through means such as spatial zoning control. From an ecological perspective, there are regional differences in the living space provided by the ecological environment on a specific biological community and its effect on its positive succession. The ecological conditions, climate characteristics and soil properties of different regions jointly shape unique ecosystems. Characteristics, which in turn affect the biodiversity, vegetation types and ecological processes of the region. Based on the ecological characteristics of different regions, scientifically analyze the current status and potential of vegetation carbon sink capacity of terrestrial ecosystems, reasonably guide urban expansion spatial patterns, and orderly protect natural resources centered on high-level carbon sink space, which will help reduce in the short term. Carbon emissions from terrestrial ecosystems caused by the expansion of unit construction land can maximize the regional carbon sink growth potential and promote the healthy development of ecosystems in the long run.

Reasonably guide the orderly transformation of carbon source space to carbon sink space. With the improvement of urban and rural land systems and the advancement of land remediation engineering technology, the redevelopment and re-restoration of developed and utilized land to achieve the transformation of land use is an important way to promote the improvement of carbon sink capacity of terrestrial ecosystems. Through timely rural land consolidation, the released land is transformed into cultivated land, which can effectively replenish the lost cultivated land resources due to urban expansion, and thereby alleviate the indirect loss of carbon sinks in terrestrial ecosystems caused by the displacement of cultivated land. At the same time, for some areas that are not suitable for reclamation into cultivated land due to water and soil conditions, ecological restoration projects, such as species introduction, ecological corridor construction, ecological migration, near-natural forestry, etc., can release a large amount of natural and semi-natural ecological spaces contribute huge potential to the growth of carbon sinks in terrestrial ecosystems.

Specific paths for low-carbon land space development

Promote a low-carbon shift in urban sprawl and growth management. The delineation of urban expansion boundaries is one of the key strategies internationally for urban sprawl and growth management issues. Land planning, land ownership control and other land regulation and management methods can be used to clarify the boundary between urban areas and rural areas, and limit legal urban development rights within this boundary to control the growth of urban spatial scale. However, urbanization construction and development require certain land as a guarantee. In order to ensure the carbon sequestration capacity of terrestrial natural ecosystems and enhance the carbon sink growth potential, the urban spatial growth management model needs to be fundamentally changed. Under my country's unique land and local fiscal system, many cities are facing the problem of a significantly high proportion of industrial land and a low proportion of residential land. Therefore, to promote the low-carbon shift in urban sprawl and growth management, we advocate adjusting the land use structure within the existing urban built-up areas, replacing unused land and land with poor comprehensive benefits, reconfiguring, and continuously updating and improving urban internal land use functions and land carrying capacity. In addition, during the process of urban renewal, we should consciously improve the carbon sequestration capacity of urban areas through measures such as increasing green space, increasing green coverage, and improving urban vegetation structure, and replenish more carbon sink sources for the region.

Improve the priority of carbon sink functions in the regulation of land and space use. At present, my country's use control system has been widely used in natural resource fields such as land, forests, waters, and grasslands, that is, mandatory means are used to implement special protection for important ecological spaces such as nature reserves, wetland parks, and forest parks. The new round of land and space planning clarifies the land and space management model with ecological protection red lines as the core, aiming to "guard the boundaries of natural ecological security with one red line." However, the delineation of ecological protection red lines is mainly based on ecological functions such as water conservation, soil and water conservation, wind prevention and sand fixation, and biodiversity maintenance. The ecosystem carbon sink function has not yet been included in the basis for dividing red line areas. Under the background of "carbon neutrality", the carbon sink function of ecosystems and the importance of ecological products are increasing day by day. It is necessary to include areas with high carbon sink levels and concentrated distribution into the scope of ecological protection red lines and implement normative and institutionalized Use control strategies.

It is recommended that maintaining regional "carbon neutrality" development goals be one of the key responsibilities of the ecological protection red line system. First, with the help of scientific carbon sink estimation methods and high-resolution spatial data, the spatial distribution of carbon sink levels in terrestrial ecosystems in the region is obtained, and then high-level carbon sink (potential) areas that need to be included in the ecological protection red line are identified. Secondly, improve the priority of ecosystem carbon sinks in the use management and ecological protection and restoration of red line areas. On the one hand, increase the supervision and enforcement of ecosystem carbon sinks. Based on the regional carbon neutrality goal and the background of ecosystem carbon reserves, determine and decompose the goals and tasks of ecosystem carbon sink spatial management and quality improvement, and clarify the supervision and assessment requirements for continuous consolidation and improvement of carbon sink capabilities. On the other hand, strengthen supervision of the effectiveness of ecological protection and restoration of carbon sinks. Incorporate ecosystem carbon sinks into the supervision and effectiveness evaluation of ecological protection red lines, so as to give full play to the guiding and counteracting role of ecosystem carbon sinks in ecological protection and restoration, and strengthen the ability of ecological protection, restoration and carbon fixation in the region.

Explore the carbon sink growth potential of urban and rural overall planning. Use "global planning" to guide the low-carbon transformation of urban and rural land use and establish an urbanization development model based on land remediation. Low-carbon-oriented optimization of land spatial pattern does not blindly restrict development or pursue spatial growth of carbon sinks. Its construction must not only meet the land demand in the urbanization process, but also ensure that the total amount of cultivated land does not decrease and the quality does not decline. At the same time, it must pursue the increase in the total amount of land carbon sinks. In order to effectively resolve the contradictions and conflicts in land use under multiple goals, it is necessary to establish a planning concept with the whole region's land recycling as the core, and at the same time adopt planning implementation methods based on land remediation.

Urban and rural land recycling aims to regard cities and villages as an organic whole, coordinate planning and construction land layout in accordance with the principle of "people-land linkage", and achieve long-term dynamic balance of total regional land use. In addition to the reform of the rural land system and household registration system,"global planning" is also needed to guide the revitalization of idle homestead resources, curb illegal land use, and promote reasonable land use for rural construction. Therefore, it is necessary to accurately count the rural population and the scale of homestead renovation, understand the geographical location and natural conditions of abandoned and long-term idle homestead, and divide centralized building areas, reclamation and multiple planting areas, and ecological restoration areas. On this basis, we will follow the principle of planning first and land use later to meet the demand for homestead for new households and reasonably promote rural land improvement and ecological restoration projects.

Author's unit: Yue Wenze, Vice President of the Institute of Land and National Development, Zhejiang University; Wang Tianyu, PhD, Institute of Land and National Development, Zhejiang University; Li Linlin, Associate Researcher, Institute of Land and National Development, Zhejiang University