Abstract: The growth of natural birch(Betula platyphylla) in different habitats (wet and moderate-water habitats) was studied. The results showed that the density and DBH of natural birch in different habitats were significantly affected by soil water. The density of birch forest in moderate-water habitat was lower than that growing in wet habitat, decreased by 46.8%. The DBH of birch in wet habitat was higher than that growing in moderate-water habitat, increased by 52.4%. The DBH distributions of birch in moderate-water and wet habitats were normal and left-skewed distributions, respectively. The DBH and height growing processes were impacted by soil water. The volume growing process was slightly affected by soil water. The fast time of DBH increment in wet habitat was longer than that in moderate-water habitat, the former was 6～15 year, the latter was 9～12 year. The mature age of DBH in moderate-water habitat was 1～2 year older than that in wet habitat. The fast time of height incerment in wet and moderate-water habitat was 6 year. The mature age of height in wet habitat was 3~6 year older than that in moderate-water habitat. The fast time of volume increment in wet and moderate-water habitat was excess to 24 year. The mature age of volume in wet and moderate-water habiat was also excess to 24 year.

Key words: Betula platyphylla, wet habitat, moderate-water habitat, growing process