Relations among litters, soil nutrients and fine root biomass of Casuarina equisetifolia in the north of Hainan Island

The relations among litters,soil nutrients and fine root biomass of Casuarina equisetifolia plantation as windbreak were studied by comparing treatment (litters removed) and control (litters preserved) sites on the coast of Gui Linyang,Haikou City. The main results were as follows:(1)Annual litters in the sites of treatment and control were 6.0162 t·hm-2 and 5.9505 t·hm-2 respectively. According to the statistic analysis,there was no significant difference between the two sites. It seemed that the temporal patterns of litters were similar in the two sties. In the components of litters,the leaf litters took up the largest percentage and their monthly dynamics were similar with the total litters. The miscellaneous litters took the second place. Bark and branches litters took the least percentage;(2)It seemed that there was a same monthly pattern of N,P and K return from the litters in the two sites respectively. The order of quantity about the nutrients returned from the leaves was NKP;(3)If there was no fresh litter in the treatment site in a short time,the soil nutrients had no significant between the two sites;(4)The seasonal dynamics of fine root biomass had a "single apex" respectively and no significant difference between the two sites during the experiment,but with the time’s increase,the treatment site’s fine root biomass had a lower trend than the control site. Maybe one of the reasons on reducing the fine root biomass was litter clearing.