Structure and dynamics of a mountain riparian forest at an upstream valley in central Japan

This paper reports the data collected in censuses of trees, litter fall, and vegetation in a mountain riparian forest, upstream of the Watarase river, Gunma Prefecture in central Japan. A 1-ha permanent plot (100 m × 100 m) subdivided into horizontal 10 m × 10 m grid cells was established in the forest in 2005. Tree census with woody species > 15 cm girth at breast height was conducted every year from 2005. Twenty-five litter traps were set in the permanent plot. The samples of litter fall were collected monthly, except in winter, between 2005 and 2008. And we sorted into leaves, branches, reproductive organs and other plant material, at species level as much as possible. The percentage cover of vascular plants was recorded at each vertical stratification (tree layer, sub-tree layer, shrub layer, and herb layer) in 2008 and 2014 at the plot. These data are valuable for elucidating long-term forest dynamics at mountain upstream areas experiencing frequent ground disturbances.