The University of Tokyo Hokkaido Forest (UTHF) is located in a hemiboreal mixed forest zone and is predominantly characterized by boreal conifers such as Abies sachalinensis, Picea jezoensis, and Picea glehnii and cool-temperate deciduous broadleaves such as Tilia japonica, Acer pictum, Betula spp., and Quercus crispula. As an ecotone, the forest composition within the UTHF varies with elevation, transitioning from a cool temperate deciduous broadleaf-dominant forest at lower elevations to an alpine dwarf pine (Pinus pumila) forest at the highest point. The vegetation associated with specific disturbances, topography, or geography serves as a habitat for diverse species. Over the span of more than 60 years, the UTHF has conducted long-term measurements of forest trees. In addition to numerous small forest plots (typically smaller than 1 hectare), there are two large-scale long-term ecological research (LTER) plots: Maeyama LTER (36.25 hectares) and Iwanazawa LTER (18.75 hectares). These extensive monitoring efforts have elucidated the dynamics and environmental changes in hemiboreal forests. The UTHF has established several experimentally designed study plots utilized for assessing biodiversity-ecosystem functional relationships and the genetic local adaptations of trees to elevational gradients. Long-term observations of plant phenology have also been conducted, providing robust evidence for plant responses to climate change. The comprehensive research conducted at the UTHF contributes significantly to our understanding of hemiboreal forest ecosystems.