title: Estimation of fine-root production using rates of diameter-dependent root mortality, decomposition and thickening in forests.
abstract: Current studies indicate that fine roots of different diameter classes show different rates of decomposition. This study developed a new method to estimate fine-root production by considering the difference in the production of fine roots of two size classes, fine roots thinner than 1 mm and those between 1 and 2 mm, and their corresponding rates of decomposition. A litter bag experiment was used to estimate the decomposition rates, while the sequential soil core technique was used to identify mass values of live roots and dead roots at a given period of observation. The continuous inflow method was applied to estimate the amount of root decomposition, mortality and production with a framework of two diameter classes of fine roots and for quantification of the amount of mass transfer from the thicker fine-root class to the coarser root category (>2 mm). The results indicated that the estimate of fine-root production was greater when two size classes of fine roots were distinguished. Using a framework of two size classes developed in this study resulted in 21.3% higher fine-root production than a method that did not recognize fine-root size classes or mass transfer to the category of coarse roots. In addition, using shorter collection intervals led to higher production estimates than longer intervals. The production estimate with a 1-month interval was 21.4% higher than that with a 6-month interval. We consider that the use of the sequential soil core technique with continuous inflow estimate method by differentiating size classes of fine roots is likely to minimize the underestimation of the parameters of fine-root dynamics by accounting for decomposition and mortality of fine roots more appropriately.
authors.affiliation: Sivilculture Research Institute, Vietnamese Academy of Forest Sciences, Hanoi 100-000, Vietnam Center for Southeast Asian Studies, Kyoto University, Kyoto 606-8501, Japan Department of Forest Vegetation, Forestry and Forest Products Research Institute, Tsukuba 305-8687, Japan dotran@cseas.kyoto-u.ac.jp dotranvan@hotmail.com.
authors.forename: Tran
authors.initials: T
authors.lastname: Van Do
authors.affiliation: Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan Graduate School of Global Environmental Studies, Kyoto University, Kyoto 606-8501, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Osawa
authors.affiliation: Department of Forest Vegetation, Forestry and Forest Products Research Institute, Tsukuba 305-8687, Japan.
authors.forename: Tamotsu
authors.initials: T
authors.lastname: Sato
mesh_terms: D065928:Forests; D007564:Japan; D018517:Plant Roots / Q000033:anatomy & histology / Q000254:growth & development*; D029963:Quercus / Q000254:growth & development*; D012987:Soil; D014197:Trees / Q000254:growth & development*
chemical_list: D012987:Soil
keywords: continuous inflow method; decomposition; fine-root diameter classes; root thickening; sequence soil core