Abstract:

This paper describes research on change of the decay leaf microorganisms and leaf-litter decomposition in process of natural decomposition by man-made initation in Kandelia mangroves of Jiulongjiang River Fsturay.The results showed that:

1.Total amounts of microorganisms of the decay leaves varies significantly during the decomposition process, all along the bacterial amounts was preponderance. The amounts of bacterial increase from 200 × 104 to 8800 × 104ind./ g.d.w, with decomposition time of leaves. That accounted for 96 to 99% of total amounts of microorganisms (including three grounp of bacteria, actinomyces and filamentous fungi etc. ) which showed the bacteria as major microorganisms in leaf-litter decomposition.

2.The ammonifying bacteria preponderate in number from 26× 104 to 180 × 104 (ind./g.d.w.in various physiologic group of microorganisms; whereas nitrite bacteria, denitrifying bacteria and celluase decomposing microorganisms were (ind./g.d.w) 0.03×104 to 0.24×104, 0.03×104 to 0.10 ×104 and 1.14× 10 to 7.33×10 respectively. This showed that the ammonifying bacteria was the major physiologic group of organic mineralization. Ammonification, nitrification and denitrifying were the accompying processes with increasing intensity as time elapsed which reflect the features of marsh. The amounts of cellulose decomposing microorganisms had changed exceptional, population increased at earlier stage of decomposition until the fourth week to the its peck value, and decreased thereafter. The microbial activation testing result showed the similar trends in the change of microbial physiologic group mentioned above.

3. The leaf-litter decomposition speed proceeded rapidly. One week after the drop of the leaves on the soil surface, one quarter of the organic matters was decomposed and half-decomposition time was about 6 weeks. The contents of soluble sugar and total phosphorus decreased, but total nitrogen increased in remainder leaves.