Invasion Risk and Management Strategy of Dysphania ambrosioides in Urban Green Spaces Driven by Imported Topsoil
摘要
[目的]客土输入是城市绿地植物入侵的重要诱因,探明客土干扰下群落物种种间关系特征,对科学评估入侵风险、制定精准阻控策略极其重要.[方法]以成都市龙泉驿区城市待建绿地因客土滋生的土荆芥(Dysphania ambrosioides)群落为对象,采用样方调查法、生态位理论、种间联结性和相关性分析,解析其结构特征、种间关系及潜在入侵风险.[结果]群落中有草本植物51种,入侵种占39.2%(20种).土荆芥为新增入侵种,重要值(I=14.8)和生态位宽度(BL=29.0)居群落首位,具极强环境适应性与资源利用能力.物种间整体呈不显著正联结(VR=1.28,W=47.5),χ2检验、联结系数、Pearson相关系数和 Spearman 秩相关系数分析显示,群落种间联结微弱,物种趋向独立分布,以此避免激烈竞争而共存.土荆芥与空心莲子草(Alternanthera philoxeroides)、苦苣菜(Sonchus oleraceus)、马唐(Digitaria sanguinalis)、牛筋草(Eleusine indica)的生态位重叠指数高于平均值,但与群落主要物种关联不显著.[结论]微弱的种间关联减少了扩散阻力,促使土荆芥占据生态位优势.建议城市绿地建设建立严格客土准入管控机制,从源头阻断入侵植物传播途径,保障区域生态安全.
[Objective]Imported topsoil has been recognized as a critical pathway for plant invasions in urban green spaces.Understanding the interspecific relationships within plant communities under imported topsoil disturbance is essential for accurately evaluating invasion risks and developing effective control strategies.[Methods]This study investigated a Dysphania ambrosioides community that spontaneously colonized imported topsoil in a reserved green space in Longquanyi District,Chengdu.Field vegetation surveys were conducted using quadrat sampling.Ecological niche theory,interspecific association analysis,and correlation analysis were integrated to characterize community structure,patterns of interspecific relationships,and potential invasion risks.[Results]A total of 51 herbaceous species were recorded in the community,including 20 invasive species,accounting for 39.2%of the total.D.ambrosioides was identified as a newly recorded invasive species in the study area.It exhibited the highest importance value(I=14.8)and niche breadth(BL=29.0)among all surveyed species,establishing it as the dominant species with strong environmental adaptability and resource utilization capacity.The overall interspecific association among species showed a nonsignificant positive trend(VR=1.28,W=47.5).The χ2 test,association coefficient,Pearson correlation coefficient,and Spearman's rank correlation coefficient consistently indicated weak interspecific associations.Most species displayed independent distribution patterns,which may promote coexistence by mitigating intense interspecific competition.The niche overlap indices of D.ambrosioides with Alternanthera philoxeroides,Sonchus oleraceus,Digitaria sanguinalis,and Eleusine indica were all above the community average;however,its associations and correlations with the other dominant species were not significant.[Conclusion]The weak interspecific associations may reduce biotic resistance to the establishment and expansion of D.ambrosioides,thereby facilitating its dominance within the community.To safeguard regional ecological security,stringent soil-entry approval protocols should be implemented during urban construction to prevent the introduction and spread of invasive plants at the source.
