Comprehensive evaluation criteria for plants.

The field of landscape architecture has placed significant emphasis on low-carbon landscapes due to the increasing challenges posed by global warming and environmental deterioration in recent years. The soil ecological conditions in saline–alkaline areas are characterized by poor quality, resulting in suboptimal growth conditions for trees. This, in turn, hampers their ability to effectively sequester carbon, thereby diminishing the potential benefits of carbon sinks. Additionally, the maintenance of tree landscapes in such areas generates more carbon emissions than does conventional green land, making it difficult to reap the benefits of tree-based carbon. A comprehensive evaluation of trees in green park spaces in saline–alkaline areas is conducted from a low-carbon perspective; by identifying the dominant tree species that are well suited to greening, we can offer a precise scientific foundation for implementing low-carbon greening initiatives in cities situated in saline–alkaline environments. Therefore, as a case study, this study investigates Tianjin Qiaoyuan Park, a typical saline park in the Bohai Bay region. The hierarchical analysis method (AHP) was used to evaluate 50 species of trees and shrubs in the park from a low-carbon perspective. The results show that the evaluation system consists of four criterion layers and 15 indicator factors. The relative weight of the criterion layer followed the order of habitat adaptability (B2) > carbon sequestration capacity (B1) > low-carbon management and conservation (B3) > landscape aesthetics (B4). The indicator layer assigned greater weight values to net assimilation (C1), saline and alkaline adaptability (C3), drought tolerance (C4), irr igation and fertilization needs (C8), growth rate (C2), and adaptability to barrenness (C5). The trees were classified into five distinct categories, with each exhibiting significant variation in terms of the strengths and weaknesses of the indicators. According to the comprehensive score, the trees were categorized into three levels. The Grade I plants exhibited the best carbon efficiency performance, comprising a total of 12 species (e.g. Sabina chinensis, Fraxinus chinensis ’Aurea’ and Hibiscus syriacu), and demonstrated superior performance in all aspects. Grade II trees, consisting of 26 species (e.g Pinus tabuliformis, Paulownia fortunei, Ligustrum × vicaryi), had the second-highest comprehensive score. Moreover, Grade III trees, encompassing 12 species (e.g Acer mono, Cedrus deodara, Magnolia denudata), exhibited lower comprehensive scores. The extensive use of Grade I and II tree species is recommended in the implementation of low-carbon greening projects in the Bohai Bay region, while Grade III tree species should be judiciously utilized. The findings of this research can serve as a valuable resource for the scientific identification of tree species that are suitable for urban park green spaces in the Bohai Bay region, which is characterized by predominantly saline and alkaline soil. Additionally, the development of an evaluation system can guide the selection of low-carbon tree species when evaluating other types of saline and alkaline lands.近年来，随着全球变暖与环境恶化带来的挑战日益严峻，风景园林学（Landscape Architecture）领域愈发重视低碳景观的研究与实践。盐碱地区的土壤生态条件普遍较差，导致树木生长状况不佳，进而削弱了其有效固碳（sequester carbon）的能力，降低了碳汇（carbon sinks）的潜在效益。此外，该区域树木景观的管护碳排放高于常规绿地，难以实现树木固碳的预期收益。 本研究从低碳视角出发，对盐碱地区城市公园绿地中的树木开展综合评价，通过筛选适配城市绿化的优势树种，为盐碱地区城市实施低碳绿化举措提供精准的科学依据。为此，本研究选取环渤海湾地区典型盐碱公园——天津桥园公园作为案例展开研究。采用层次分析法（AHP）对该公园内的50种乔灌木进行低碳视角下的综合评价。 研究结果显示，本次构建的评价体系包含4个准则层与15项指标因子。准则层的相对权重排序为：生境适应性（B2）＞固碳能力（B1）＞低碳管护（B3）＞景观美学（B4）。指标层中，净同化量（C1）、盐碱适应性（C3）、耐旱性（C4）、水肥需求（C8）、生长速率（C2）以及耐贫瘠性（C5）的权重值相对更高。 参评树木被划分为5个类别，各类别在指标优劣表现上存在显著差异；结合综合得分进一步将其分为3个等级。一级树种的碳效率表现最优，共计12种，如圆柏（Sabina chinensis）、金叶白蜡（Fraxinus chinensis ’Aurea’）、木槿（Hibiscus syriacus）等，其在各指标维度上均表现优异。二级树种共计26种，如油松（Pinus tabuliformis）、泡桐（Paulownia fortunei）、金叶女贞（Ligustrum × vicaryi）等，综合得分位列第二。三级树种共计12种，如五角枫（Acer mono）、雪松（Cedrus deodara）、玉兰（Magnolia denudata）等，综合得分相对较低。 研究建议在环渤海湾地区的低碳绿化工程中广泛应用一级与二级树种，而三级树种应谨慎选用。本研究成果可为环渤海湾盐碱土壤占主导的城市公园绿地适配树种的科学筛选提供重要参考，同时所构建的评价体系也可为其他类型盐碱土地的低碳树种遴选提供指导。