Karuizawa is home to many living things, including trees, wildflowers, wild birds, and animals.
Karuizawa, located on a plateau at an elevation of 950 to 1,200 meters above sea level, welcomes spring about a month later than the flatlands of the Kanto and other regions. After a short, fog-shrouded summer, the leaves begin to change color in September, and then fall in November, leaving the forests to wither and die for another winter, followed by a continuous sub-zero winter. The temperature varies widely throughout the year, but there are also differences in temperature from one day to the next. This varied climate nurtures the lives of many living creatures.
Looking at the town as a whole, there are a variety of environments, from the alpine flora of Mt. Asama to the Quercus crispula forests at the foot of the mountain and the wetlands of Minamikaruizawa. Numerous plants and animals inhabit these environments.
Although there are many plant species and bird species, reptiles and insects are relatively limited in variety due to the cool climate.
Many rare species also inhabit the area. Of the endangered species listed in the Nagano Prefecture Red Data Book (Endangered I and Endangered II), 57 vascular plant species and 39 animal species have been confirmed in Karuizawa. The Hanahyotanboku community in Nagakura is also listed as a highly rare plant community.