title: [C and N allocation patterns in planted forests and their release patterns during leaf litter decomposition in subalpine area of west Sichuan].
abstract: With the planted forest ecosystems of Cercidiphyllum japonicum, Betula utilis, Pinus yunnansinsis, and Picea asperata in subalpine area of west Sichuan as test objects, their total biomass and the C and N contents in soils and tree organs were determined. The results showed that the allocation of C in tree organs had less correlation with the age of the organs, while that of N and C/N ratio had closer relationship with the age. The N content in young organs was higher than that in aged ones, whereas the C/N ratio was higher in aged organs than in young organs, and higher in the leaf litters of needle-leaved forests than in those of broad-leaved forests. There was an obvious enrichment of C and N in the topsoil of test forests. The accumulated amounts of C and N in the whole planted forest ecosystem, including tree, litter, and 0-40 cm soil layer, were 176.75-228.05 t x hm(-2) and 11.06-16.54 t x hm(-2), respectively, and the nutrients allocation ratio between soil-litter and tree was (1.9-3.3):1 for C and (15.6-41.5):1 for N. Needle-leaved forests functioned as a stronger "C-sink" than broad-leaved forests. The decomposition rate of the leaf litters in needle-leaved forests was larger than that in broad-leaved forests, with the turnover rate being 2.2-3.7 years and 3.9-4.2 years, respectively. During the decomposition of leaf litter, the C in all of the four forests released at super-speed, with the turnover rate being 1.9-3.4 years. As for N, it also released at super-speed in C. japonicum and B. utilis forests, with the turnover rate being 1.9-3.2 years, but released at low speed in P. yunnansinsis and P. asperata forests, with the turnover rate being 6.7-8.5 years.
authors.affiliation: College of Resources Environment, Northwest A & F University, Yangling 712100, Shaanxi, China. zengwenliu2003@yahoo.com.cn
authors.forename: Zeng-wen
authors.initials: ZW
authors.lastname: Liu
authors.forename: Er-jun
authors.initials: EJ
authors.lastname: Duan
authors.forename: Kai-wen
authors.initials: KW
authors.lastname: Pan
authors.forename: Li-ping
authors.initials: LP
authors.lastname: Zhang
authors.forename: Hong-xia
authors.initials: HX
authors.lastname: Du
mesh_terms: D000531:Altitude; D029662:Betula / Q000254:growth & development / Q000378:metabolism; D002244:Carbon / Q000032:analysis*; D002681:China; D017753:Ecosystem; D009584:Nitrogen / Q000032:analysis*; D028222:Picea / Q000254:growth & development / Q000378:metabolism; D028223:Pinus / Q000254:growth & development / Q000378:metabolism; D018515:Plant Leaves / Q000378:metabolism*; D012987:Soil / Q000032:analysis*; D014197:Trees / Q000254:growth & development / Q000378:metabolism*
chemical_list: D012987:Soil; D002244:Carbon; D009584:Nitrogen