Abstract:

The distribution and circulation of 8 nutrient element contents and accumulation in the 10a artificial Cercidiphyllum japonicum community were studied.The results indicate:(1)The order of average content of elements in organs is Ca>N>Al>K>Mg>P>Fe>Mn.(2)The order of different organs for element accumulation is roots>leaves>stems without barks>barks>branches,and the order of elements accumulation is Ca>N>K>Al>Mg>P>Fe>Mn.(3)The amount of uptake,retention and return of 8 elements in the community is 729 82 kg·hm^-2a^-1、206.72kg·hm^-2a^-1 and 523.10kg·hm^-2a^-1,respectively.(4)51.2% of total return for K is returned through rainfall leaching,55.7%～96.5% of the rests through litter.However,41.3% of total return for Fe and 44.3% for Al is still returned through dead roots,respectively.(5)Utilization coefficient,ratio of return to uptake,circulation period were 0.23～0.54、0.57～0.82 and 2.26～7.63.Meanwhile,the calculating method of nutrient elements returning through leaching was amended,and the uptake coefficient(annual element uptake/annual available element in soil),accumulation coefficient(annual element accumulation/annual available element in soil)and return coefficient(annual element return/annual available element in soil)were put forward.Finally,the calculating method of element circulation for deciduous forest was discussed.

Key words: Cercidiphyllum japonicum, Nutrient elements, Content, Accumulation, Circulation