Previous studies have examined whether the magnitude of tsunami impacts on coastal forests differs according to the density and size structure of the trees. However, few studies have focused on how monoculture/mixed forest settings and tree spatial arrangements in coastal forests can mitigate tsunami impacts. Here, satellite images and aerial photographs taken before and after the tsunami events triggered by the Great East Japan Earthquake on March 11, 2011, were used to compare the degree of damage to coastal forests between monoculture (black pine only) and mixed forests (black pine and other broad-leaved tree species) as well as between forests with different tree planting spatial patterns. We found that mixed coastal forests were less vulnerable to tsunami impacts than were black pine monoculture coastal forests, and that mixed coastal forests with a more complicated spatial structure were less vulnerable than were simply structured mixed forests. The functional complementarity of mixed coastal forests leads to enhanced tree growth and physical stability, which may decrease the vulnerability of these forests to tsunami impacts. Maintaining mixed coastal forests with black pine and increasing forest spatial complexity is critical for the management of coastal forests to mitigate effects of tsunami disasters.
Datasets used to create the main figures and tables in the paper: Plant and soil microbial community assembly processes across urban vacant lots. The file (Plant_spmatrix_all_t.csv, Plant_spmatrix_Native_t.csv, Plant_spmatrix_Exotic_t.csv) is plant community composition (a value in each cell represents species cover) data along each survey transect across urban vacant lots in Yokohama. The file (Plant_name.csv) includes nomenclature and its abbreviation. The files (OTU_table_bacteria.csv, OTU_table_fungi.csv) are bacterial and fungal community composition (a value in each cell represent number of reads) along each survey transect across urban vacant lots in Yokohama (note that presence/absence data for bacteria and fungi was used in the paper). The file (All explanatory variables_vacant lots.csv) is the data of explanatory variables used to explain plant and microbial community composition along each survey transect across urban vacant lots in Yokohama.
Datasets used to create the main figures and tables in the paper: Overlooked plant diversity in urban streetscapes in Oulu and Yokohama. The file (plant_oulu.csv) is plant community composition (presence/absence) data across urban streetscapes in Oulu. The file (plant_yokohama.csv) is plant community composition (presence/absence) data across urban streetscapes in Yokohama.
Abstract Plant communities are impacted by local factors (related to environmental filtering) and landscape factors (related to dispersal limitation). While many studies have shown that the relative importance of these factors in understanding plant community dynamics due to urbanization, little is known about how they are altered by urbanization—a significant threat to biodiversity. This study evaluates the relative importance of local environmental (local factors), landscape, and spatial (landscape factors) variables that influence plant communities in 34 urban green spaces comprising two different habitats (forests and grasslands) along the urban–rural gradients in the Tokyo megacity, Japan. To continuously assess the relative importance of each factor along the urban–rural gradients, we extracted 1000 landscapes within a certain range that contained several sites. Subsequently, the relative importance of each factor and urbanization rate (proportion of artificial built‐up area) were estimated for each landscape. Our study found that the relative importance of both local and landscape factors decreased, while that of local factor for native species in forest habitats and that of landscape factors for native species in grassland habitats increased. Collectively, these findings suggest that city size and habitat characteristics must be considered when predicting changes in plant communities caused by urbanization.
Streets comprise a major area of urban land use and connect built areas to one another. However, the role of streetscapes for maintaining urban plant diversity remains poorly understood. In this study, urban street vegetation was investigated in Oulu, Finland, and Yokohama, Japan, to explore how species richness and composition of plant communities change among different street habitat types, including road-verge grass beds, asphalted surfaces, stone pavements, curbside gaps, wall bases, street shrubbery, and tree bases. All plant species were recorded separately for different street habitat types along a maximum of 500 m of street sections. The gamma diversity of each habitat type and the contributions of native and exotic species were evaluated based on species accumulation curves. Plant species composition was examined using non-metric multidimensional scaling and Venn diagrams. A total of 145 and 273 species were recorded in Oulu and Yokohama, respectively. In Oulu, native species contributed more to the total diversity across habitat types, whereas in Yokohama, we observed similar contributions of native and exotic species to the total diversity. There was a large overlap in species occurrence among different habitat types in Oulu, where the road-verge grass beds included over 90 % of the total diversity, and all species present in asphalted habitats. Road verge grass beds in Oulu and street shrubbery in Yokohama include a large number of unique species, implying that these species have adapted to the environment in each habitat. Thus, streetscape vegetation includes a mixture of common urban species and some unique species depending on habitat type, which is often overlooked as a part of the spontaneous plant diversity across streetscapes. We propose that diverse street habitats, including both gray and green surfaces, support diverse plant species and may thereby create biodiverse urban streetscapes.
Abstract Questions Numerous studies on community assembly processes have been conducted in natural ecosystems. However, we know little about community assembly processes in human‐dominated urban ecosystems. Here, we asked: (1) how are the composition and functional diversity of native and exotic plant species shaped by local environment and landscape factors across urban vacant lots; and (2) how is microbial (bacterial and fungal) community composition influenced by the local environment, landscape factors, and plant species composition across urban vacant lots? Location We investigated 69 urban vacant lots in Yokohama, Japan. Methods By using a variation partitioning approach, we examined the relative importance of local environmental and landscape factors (including land use and spatial structure) in explaining variation in plant species composition and functional diversity of native or exotic species. We also explored the relative importance of local environmental and landscape factors, and plant species composition in explaining variation in microbial community composition. Results The spatial structure of vacant lots determined the species composition and functional diversity of plant communities, suggesting that plant community assembly is determined by dispersal limitation. However, the functional diversity of the exotic species varied randomly, which reduced the relative importance of the spatial structure of vacant lots. Plant species composition as well as the spatial structure of vacant lots were the important drivers of the composition of soil microbial communities, despite a higher proportion of unexplained variation in their composition. Finally, we found an essential contribution of earthmoving methods in explaining the variations in both plant and microbial community composition. Conclusion Plant and microbial community composition would be largely determined by dispersal limitation across urban vacant lots. Understanding urban community assembly is critical for predicting plant and microbial communities that play an essential role in regulating urban ecosystem functioning and services.
