Litterfall Production and Nutrient Return Dynamics of Acacia aulacocarpa Plantation in a Coastal Sandy Plain Area

A twelve-month field study was conducted to measure litterfall production and its nutrient return characteristics of a Acacia aulacocarpa plantation forest in a coastal sandy plain area from October 2011 to September 2012 in Changle, Fujian. The results showed that the annual litterfall production in the studied plantation site was 5.3t/hm2, the quantity of the litterfall dynamically changed along the seasons, expressing ‘single peak’ in June 2012. Leaf litter was the main component and accounted for 67.85% of total amount, followed by branches, miscellaneous leaves, debris, miscellaneous fruits, fruits, flowers, miscellaneous branches and bark. The average concentrations of 5 macronutrient elements in the litterfall decreased in the following order N>K>Ca>Mg>P. The fluxes of these 5 macronutrient elements in the litterfall was 127.98kg/(hm2·a), the annual flux of nitrogen was maximum, which content was 75.63kg/(hm2·a); and the annual flux of phosphorus was minimum, which content was 2.24kg/(hm2·a). These 5 macronutrient return patterns were similar, and reached the maximum in July, the annual returns of these four trace elements（Fe、Mn、Zn、Cu）were 1.272kg/(hm2·a), 2.261kg/(hm2·a), 0.192kg/(hm2·a), 0.023kg/(hm2·a). In plant of litterfall, concentration of Mn was the highest among the four elements, followed by Fe, Zn, while Cu was the lowest in various components of Acacia aulacocarpa plantation.