最佳网格分析尺度下城市绿色基础设施的 景观格局对碳汇绩效的影响研究

Influence of Urban Green Infrastructure Landscape Pattern on Carbon Sequestration Performance at the Optimal Grid Unit

关键词:  风景园林  城市绿色基础设施  碳汇绩效  景观格 局  CASA模型  最佳网格分析尺度

Key words:  landscape architecture  urban green infrastructure  carbon sequestration performance  landscape pattern  CASA model  optimal grid analysis unit

摘要:

有效规划和管理城市绿色基础设施(UGI)的组成和 结构以维持高水平的UGI碳汇绩效对于节约国家资源和应对气 候变化至关重要。然而目前UGI景观格局对碳汇绩效的影响因 素仍不明确，因此，旨在量化UGI景观格局对碳汇绩效的影 响，为低碳导向下UGI的管理和优化决策提供理论基础。首 先，利用景观指数法对武汉市UGI景观格局进行多尺度量化。 然后使用哨兵2号数据改进的CASA模型、生物量-碳转换系 数评估了多尺度下武汉市UGI的碳汇绩效。并整合莫兰指数和 半变异函数识别了武汉市UGI景观格局和碳汇绩效的本征尺 度。最后，以本征尺度为最佳网格分析尺度揭示了UGI景观格 局对碳汇绩效的关键影响因子。结果表明：1)武汉市UGI碳 汇绩效不存在城乡梯度差异但依然存在空间分异和空间聚集特 征；2)2.5km是最佳网格分析尺度，宜作为低碳导向下武汉 市UGI的最佳管理单元；3)UGI碳汇绩效与耕地、湿地占比 和聚集度呈负相关，而与林地、草地占比和聚集度成正相关， 林地的高连通度也意味着UGI的高碳汇能力。此外，湿地和林 地的形状指数对碳汇绩效也有显著影响。建议在2.5km尺度 下从增加林地占比、构建绿廊、减少冬闲田、碳汇树种选址种 植等方面提升UGI的碳汇绩效。

Abstract:

Effective planning and management of urban green infrastructure (UGI) composition and structure to maintain its good performance as a carbon sink is crucial for preserving resources and coping with climate change. However, the influence of UGI landscape patterns on the carbon sequestration performance remains elusive. This study aims to quantify the impact of UGI landscape pattern on the performance of carbon sequestration, and thus provide a theoretical basis for the assessment and optimization of UGI under a low-carbon orientation. Firstly, the landscape index was used to quantify the UGI landscape pattern in Wuhan. Then, the performance of UGI carbon sequestration in Wuhan was assessed at multiple scales by combining the Sentinel-2 improved CASA model and biomass-carbon conversion coefficient. Subsequently, the Moran's I and Semi-variogram models were integrated to identify the intrinsic scales of the UGI landscape pattern and carbon sequestration performance. Finally, the intrinsic scale was used as the optimal grid analysis unit to reveal the key factors. The results show that: 1) Although there is no urban-rural gradient in the performance of UGI carbon sequestration performance, there are certain spatial differentiation and spatial aggregation; 2) 2.5km is the best grid unit for analysis in this paper, as well as the best management unit for UGI in Wuhan under low-carbon orientation; 3) The performance of UGI carbon sequestration is negatively correlated with the proportion and aggregation degree of cropland and wetland, but positively correlated with those of tree covers and grassland. In addition, a high connectivity of tree covers also corresponds to a high carbon uptake ability of UGI. In addition, the shape index of wetlands and tree covers has great influence on the carbon sequestration performance. It is therefore recommended that the carbon sequestration performance of UGI can be enhanced through strategies such as increasing the proportion of tree covers, establishing green corridors, reducing bare cropland in winter, and rational planting of trees with high carbon sequestration capability.