2021 Volume 26 Issue 2 Article ID: 2041
Semi-natural grasslands contain high plant diversity, but they are declining worldwide. Understanding the causes of grassland decline requires clarifying changes in the total area and distribution of grasslands at the regional scale. Within Japan, previous studies have focused on grassland decline following World War II, when grassland resources were of limited anthropogenic value, and few studies have been conducted in high-elevation areas, despite the country’s complex topography. Therefore, we examined changes in the distribution of grassland areas in the Sugadaira Highlands, central Japan, over approximately 289 years (1722-2010). We quantified changes in the grassland area using topographic maps and aerial photography for the 130-year period of 1881-2010, and qualitatively estimated changes in grassland for the additional 159-year period of 1722-1881 using old maps. As of 1912, 85.3% (37.7 km2) of the total Sugadaira Highlands area was blanketed by a single continuous grassland. Records from 1722-1881 indicate that most of the study area was grassland during that period. However, by 2010, only 5.3 km2 of fragmented grassland remained. The rate of grassland decline was most rapid during the afforestation period of 1912-1937, and was more moderate during the period 1937-1947. The Sugadaira Highlands were designated a national park in 1947, after which the rate of grassland decline increased again. Relative to other areas of Japan, grassland decline in the study area has been particularly rapid. We determined no tendency of a reduced decline in grassland areas in national parks relative to the national average. To preserve biodiversity in these important landscapes, we must support natural grassland conservation and management.
