The Ecological Adaptation Strategy of Some Accumulator Plants In a Forest Dominated by Quercus Serrata In Nara, Western Japan.

In the experimental forest of Nara campus of Kinki University in western Japan, Quercus serrata and Cryptomeria japonica are the dominant and crown-position trees, and they are deciduous and evergreen species, respectively. Whereas the Quercus serrata occurs in ridge and upper slope position, the Cryptomeria japonica with needle-like leaves occurs in lower slope position and valley bottom. In the ridge and upper slope position, the soil is comparatively acidic, poor and dry. Eurya japonica Thunb., a broad-leaved evergreen tree and an Al accumulator, always grows under Q. serrata. So also Ilex pedunculosa, another broad-leaved evergreen tree growth, which however is a non-accumulator of P. However it occurs at mid slope position and its distribution is limited at the extreme ridge position where the growth of Q. serrata is usually not so good. At the mid slope position also occur Clethra barbinervis, a broad-leaved deciduous tree and an accumulator of various heavy metals (including Zn, Mn and Co), and this also grows under Q. serrata. Nutrient contents of Q. serrata showed P, K, Mg and Ca values of 1.20, 16.93, 1.46 and 13.50 mg/g, respectively in fresh leaves; and 0.65±0.33, 6.69±2.85, 1.34±0.35 and 12.79±2.68 mg/g, respectively in leaf litter. The corresponding values for E. japonica were 0.56, 15.06, 2.65 and 3.60 mg/g in fresh leaves and 0.37±0.11, 14.07±0.13, 7.69±0.23 and 17.64±0.31mg/g, respectively in leaf litter; for C. barbinervis 0.62, 25.58, 5.05 and 12.02 mg/g in fresh leaves and 0.39±0.07, 14.07±0.13, 7.69±0.23 and 17.64±0.31 mg/g in leaf litter; for I. pedunculosa 0.62, 10.27, 1.96 and 10.27 mg/g in fresh leaves and 0.38±0.11, 6.46±1.17, 1.33±0.15 and 7.85±1.14 mg/g in leaf litter. These litterfall nutrient characteristics and phenology suggest that Q. serrata benefits from the accumulator trees (Eurya japonica Thunb. and Clethra barbinervis) when these trees grow under it.