Designed habitat heterogeneity on green roofs increases seedling survival but not plant species diversity

Urban areas benefit from the ecosystem services provided by low input green roofs. However, limited substrate depth on these green roofs creates challenging conditions for plant establishment and survival, leading to industry reliance on non-native succulents. Through a green roof and glasshouse study, we assessed the impact of simple design modifications to the green roof surface, including redistribution of substrate and addition of logs and pebble piles, on both substrate temperature and moisture content. We added seeds of 26 native species and quantified seedling density, species richness and composition over a single growing season. Overall effects of microsite heterogeneity on species diversity were assessed using species accumulation curves. The modifications altered substrate temperature and moisture. Deep substrate (10-12 cm) and the presence of surface features reduced temperature by 14.6°C and, while surface features had mixed effects on substrate moisture on the green roof...城市区域可从低投入绿色屋顶（green roof）所提供的生态系统服务中获益。然而此类绿色屋顶的基质（substrate）层厚度有限，为植物定植与存活带来了严苛条件，进而导致行业依赖非本土多肉植物。 本研究通过绿色屋顶与温室实验，评估了绿色屋顶表层的简易设计改造措施（包括基质重新分布、添加原木与砾石堆）对基质温度与含水率的影响。在单个生长季内，我们播种了26种本土植物的种子，并量化了幼苗密度、物种丰富度与物种组成。研究采用物种累积曲线，评估了微生境异质性对物种多样性的整体影响。 上述改造措施改变了基质的温度与含水率。较厚的基质层（10-12 cm）与表层结构的存在可使温度降低14.6℃；尽管表层结构对绿色屋顶的基质含水率存在混合效应……