Abstract:

Litterfall, nutrient content and nutrient return in subtropical Pinus massoniana plantations were analyzed based on literature collection to quantify litter nutrient dynamics and regional characteristic of the major conifer species, which would help to provide more comprehensive and universal reference for production practice and ecological management at a regional scale for P.massoniana plantations. The results showed that: the difference of annual litterfall of P.massoniana plantations between different regions was significant and the litterfall was 331-1143 t/hm2〖DK〗·a with an average of 53 t/hm2〖DK〗·a. The litterfall difference was significant by stand age, the difference of litterfall between the class age within 10-20yearold and 20-30yearold was greater than in 0-10yearold and 30-50yearold, and the most litterfall with 10-20 and 20-30 class age were 293 times, 274 times as much as the least, respectively, while the most litterfall in 30-50 class age was only 137 times and 163 times, respectively. Litterfall in Wuxuan, Guangxi Province was increased first and then decreased with stand age, and 7yearold stand was highest in Liuzhou, Guangxi Province and following decreased first and then increased with stand age, while in the Three Gorges Reservoir Area increased with increasing stand age. Litter monthly model was bimodal in Liuzhou, Guangxi province, the deciduous peak was in February and least in March, April, while the model of the total and leaf litterfall was similar and single peak mode in the Three Gorges Reservoir Area with the highest in November and the lowest in February. The litter model in Guanzhou was different per year, the first year peak in August, there was two peak periods in the second year with in July and October, the third year in June. The difference of the same organ with the same element in different regions was lager and the litter nutrient content difference with K, Ca and Mg was higher than the N and P content. Litter nutrient content with nitrogen element was highest in the Three Gorges Reservoir Area, while P, Ca, Mg elements were highest in Sanming, Fujian Province, and K element was the highest in Longli, Guizhou Province. Nitrogen return in 23yearold stand was 345 times of that in 8yearold stand, while potassium return in 23yearold stand was 1013 times as much as in 8yearold stand in Wuxuan, Guangxi province. Nitrogen return was 1.36 times more in 7 year old than in 31 year old stand, potassium return in that was 256 times in Liuzhou, Guangxi Province. Litter decomposition rate was not significant in shortterm (one year) decomposition. Litter of different tissues and organs were affected by different environment factors and different stand with various site factors, which can be attributed to the time lagging effect and more responsive to local than to regional environment