Determinates of bryophyte diversity, in comparison with vascular plant diversity, in paddy fields

Abstract

Introduction Paddy-field landscapes play an important role in conservation of plant diversity. However, in only a few studies has bryophyte diversity been investigated in these landscapes. Therefore, we examined the characteristics and factors that determine bryophyte diversity in paddy fields. Methods Three approaches were used in this study: plant taxa, life form, and habitat type. Our aim in using the plant-taxa approach was to reveal differences between bryophytes and vascular plants in terms of landscape elements that are significant for species richness. The life-form and habitat-type approaches were used to elucidate how landscape elements determined bryophyte diversity. Generalised linear models and non-metric multidimensional scaling were used for these analyses. Results and discussion The landscape elements influencing species richness differed between vascular plants and bryophytes. Specifically, the forest area emerged as a crucial factor for bryophyte richness. Moreover, the species composition of bryophytes was determined by the forest area, influencing the prevalence of hydrophilic life forms and presence of forest-associated bryophyte species. These results can be attributed to two key functions of forest areas: supplying forest species to adjacent paddy fields, and alleviating heat and drought stress. Conclusions Bryophyte diversity in paddy fields was influenced more strongly by the surrounding forest areas than by the vascular plant diversity, owing to the vulnerability of bryophytes to drought stress. These results highlight the importance of forest–paddy mosaics for conservation of bryophyte diversity in paddy fields. Furthermore, the species composition results suggest that paddy fields can serve as suitable habitats for flood-plain bryophytes.