Forest patch size predicts seed bank composition in urban areas

• Published in: Applied vegetation science 2021-01, Vol.24 (1), p.n/a
• Main Authors: Doroski, Danica A., Duguid, Marlyse C., Ashton, Mark S., Vandvik, Vigdis
• Format: Article
• Language: English
• Subjects: Buried seeds; Composition; Forests; Functional groups; Germination; Hydroxyapatite; invasive species; life history traits; Management; native species; Parks; Parks & recreation areas; recruitment; regeneration; Rehabilitation; restoration; seed bank floristics; Seed banks; Seeds; Site rehabilitation; Species composition; Urban areas; Urban environments; Urban regeneration; Urbanization; vacant lots
• ISSN: 1402-2001; 1654-109X
• DOI: 10.1111/avsc.12534

Questions As urban areas expand around the world, understanding how to restore and maintain forests within the urban environment becomes increasingly important. Given that a comprehensive understanding of regeneration dynamics is critical to designating appropriate management interventions we ask the following: how does regeneration, vis‐à‐vis the buried seed bank, vary in heterogenous urban forests? And, can forest patch size be used to predict regeneration and consequent management interventions? Location Vacant lots and public parks throughout New Haven, CT, USA. Methods We sampled buried seed banks in 131 plots distributed across three forest patch sizes ranging from large intact parks (95–126 ha), to small parks (1–19 ha), and vacant lots (0.05–0.65 ha). We collected soil samples from the surface mineral soil and stratified them over sand in a greenhouse over a period of five months to record germination. Results By examining seed bank floristics in a range of forest patch sizes we found that species composition, nativity, and dominance of specific functional groups shifted with patch size representing a spectrum of urbanization within just one city. Seed bank floristics in large parks more closely resembled results from seed bank studies in rural forests with over 85% native germinants on average. In contrast, vacant lots were dominated by non‐native germinants and more ruderal species indicative of earlier successional stages. Seed banks in small parks were variable and in some cases were more similar to large parks or vacant lots. Conclusions Our findings suggest that large parks in urban areas may be largely self‐sustaining whereas smaller parks may require more intensive management for site rehabilitation, especially in early states of succession. Furthermore, our results confirm the highly heterogenous nature of urban forest patches and call for more systematic sampling of urban areas to capture this variation and improve management prescriptions and outcomes. Our study examined seed bank floristics in urban forest patches. We stratified our sampling by forest patch size and found significant shifts in the number, nativity, and life history traits of germinants in the buried seed bank. Our results suggest that forest patch size and island biogeography offer a helpful framework to inform more tailored management prescriptions for the urban forest.