Native biodiversity often depends on remnant vegetation for survival in agricultural landscapes. However, the size and shape of remnant patches can affect their conservation values through edge effects and isolation of ecologically important species such as foundation species. Foundation species interact with and profoundly affect other species, leading to cascading community effects if they are lost from an ecosystem. We used spinifex grass (Triodia scariosa) to investigate the patterns, processes and consequences of remnant shape and habitat degradation, including nutrient enrichment and soil compaction, for a foundation plant species in agricultural landscapes. First, we quantified differences in biotic and soil variables between narrow linear remnants and larger, more equilateral nature reserves. We then assessed whether these differences explained variation in spinifex abundance and condition. Finally, we tested whether edge effects influenced spinifex abundance. We surveyed 4230 quadrats across 282 sites in south-eastern Australia and measured the size and condition of 11,514 spinifex clumps. Linear remnants were characterised by different plant communities, elevated nutrient levels, more compact soil and higher abundance of non-spinifex grasses compared to nature reserves. Spinifex was twice as abundant in reserves than linear remnants and was negatively associated with soil compaction and soil nutrients. Spinifex condition was negatively associated with soil nitrogen and non-spinifex grasses. Linear remnants had proportionally fewer small spinifex clumps compared to reserves, suggesting lower recruitment in linear remnants. We found minimal evidence of edge effects on environmental variables, and no clear edge effect on spinifex abundance. Given the large contribution of linear remnants to native vegetation cover, measures to minimise nutrient enrichment and disturbance in these areas may help arrest potential ongoing declines in this foundation plant species in agricultural landscapes.

本地生物多样性通常依靠残留的植被在农业景观中生存。但是，残留斑块的大小和形状会通过边缘效应和隔离重要生态物种（例如基础物种）而影响其保护价值。基础物种与其他物种相互作用并对其产生深远影响，如果它们从生态系统中消失，则会导致级联的社区效应。我们用了多刺草（Triodia scariosa）调查农业景观中的基础植物物种的剩余形状和栖息地退化的模式，过程和后果，包括营养素富集和土壤压实。首先，我们量化了狭窄的线性残留物与更大，更平等的自然保护区之间生物和土壤变量的差异。然后，我们评估了这些差异是否可以解释棘突丰度和状况的变化。最后，我们测试了边缘效应是否影响了菠菜的丰度。我们在澳大利亚东南部的282个站点中调查了4230个四足动物，并测量了11,514根菠菜团块的大小和状况。与自然保护区相比，线性残留物的特征在于不同的植物群落，较高的养分水平，更致密的土壤和更高密度的非自旋草。Spinifex的储量是线性残留物的两倍，并且与土壤压实度和土壤养分负相关。菠菜状况与土壤氮素和非菠菜草呈负相关。与保留地相比，线性遗留物的小棘形团块成比例地减少，这表明线性遗留物的募集量较低。我们发现边缘证据对环境变量的影响极小，而对尖晶石丰度没有明显的边缘效应。鉴于线性残留物对原生植被的巨大贡献，在这些地区尽量减少养分富集和干扰的措施可能有助于遏制这种基础植物在农业景观中潜在的持续衰退。菠菜状况与土壤氮素和非菠菜草呈负相关。与保留地相比，线性遗留物的小棘形团块成比例地减少，这表明线性遗留物的募集量较低。我们发现边缘证据对环境变量的影响极小，而对尖晶石丰度没有明显的边缘效应。鉴于线性残留物对原生植被的巨大贡献，在这些地区尽量减少养分富集和干扰的措施可能有助于遏制这种基础植物在农业景观中潜在的持续衰退。菠菜状况与土壤氮素和非菠菜草呈负相关。与保留地相比，线性遗留物的小棘形团块成比例地减少，这表明线性遗留物的募集量较低。我们发现边缘证据对环境变量的影响极小，而对尖晶石丰度没有明显的边缘效应。鉴于线性残留物对原生植被的巨大贡献，在这些地区尽量减少养分富集和干扰的措施可能有助于遏制这种基础植物在农业景观中潜在的持续衰退。我们发现边缘证据对环境变量的影响极小，而对尖晶石丰度没有明显的边缘效应。鉴于线性残留物对原生植被的巨大贡献，在这些地区尽量减少养分富集和干扰的措施可能有助于遏制这种基础植物在农业景观中潜在的持续衰退。我们发现边缘证据对环境变量的影响极小，而对尖晶石丰度没有明显的边缘效应。鉴于线性残留物对原生植被的巨大贡献，在这些地区尽量减少养分富集和干扰的措施可能有助于遏制这种基础植物在农业景观中潜在的持续衰退。