Redefining floristic zones in the Korean Peninsula using high-resolution georeferenced specimen data and self-organizing maps

The use of biota to analyze the distribution pattern of biogeographic
regions is essential to gain a better understanding of the ecological
processes that cause biotic differentiation and biodiversity at multiple
spatiotemporal scales. Recently, the collection of high-resolution
biological distribution data (e.g., specimens) and advances in analytical
theory have led to the quantitative analysis and more refined spatial
delineation of biogeographic regions. This study was conducted to redefine
floristic zones in the southern part of the Korean Peninsula and to better
understand the eco-evolutionary significance of the spatial distribution
patterns. Based on 309,333 distribution data of 2,954 vascular plant
species in the Korean Peninsula, we derived floristic zones using
self-organizing maps. We compared the characteristics of the derived
regions with those of historical floristic zones and ecologically
important environmental factors (climate, geology, and geography). In the
clustering analysis of the floristic assemblages, four distinct regions
were identified, namely, the cold floristic zone (Zone I) in high-altitude
regions at the center of the Korean Peninsula, cool floristic zone (Zone
II) in high-altitude regions in the south of the Korean Peninsula, warm
floristic zone (Zone III) in low-altitude regions in the central and
southern parts of the Korean Peninsula, and maritime warm floristic zone
(Zone IV) including the volcanic islands Jejudo and Ulleungdo. Totally,
1,099 taxa were common to the four floristic zones. Zone IV showed the
highest abundance of specific plants (those found in only one zone), with
404 taxa. Our study improves floristic zone definitions using
high-resolution regional biological distribution data. It will help better
understand and re-establish regional species diversity. In addition, our
study provides key data for hotspot analysis required for the conservation
of plant diversity.