Fine root distribution, seasonal pattern and production in four plantations compared with a natural forest in Subtropical China

Abstract

-Fine root (< 2 mm in diameter) distribution, seasonal pattern and net production were studied during 1999-2001 in 33 year-old plantations of two coniferous trees, Chinese fir (Cunninghamia lanceolata, CF) and Fokienia hodginsii (FH) and two broadleaved trees, Ormosia xylocarpa (OX) and Castanopsis kawakamii (CK), and compared with that of an adjacent natural forest of Castanopsis kawakamii (NF, ~150 year old) in Sanming, Fujian, China. Fine root biomass and necromass were determined by soil coring at a bimonthly interval. Soil cores were divided into 10 depths: 0 ~ 10, 10 ~ 20, 20 ~ 30, 30 ~ 40, 40 ~ 50, 50 ~ 60, 60 ~ 70, 70 ~ 80, 80 ~ 90, and 90 ~ 100 cm. Litter bags (18 × 18 cm 2 size, 0.25 mm mesh) were used in determination the decay rates of fine roots (< 0.5 mm, 0.5-1 mm, and 1-2 mm). Mean annual fine-root production, mortality, decomposition and turnover rate were calculated by the compartment-flow method. Mean fine-root biomass ranged from 1.49 Mg ha -1 in the CF to 4.94 Mg ha -1 in the NF, and decreased in the following order: NF > CK > FH > OX > CF. There were significant seasonal changes of biomass and necromass in all stands (P < 0.05), while no significant yearly fluctuations were detected (P > 0.05). In all stands, an early spring (March) peak of fine root biomass was found, and the minimum value occurred mainly in dry summer or cold winter. For the NF, 59.8% of fine root biomass was found in the top soil of 0-10 cm, a layer that maximum difference of depth distribution among all stands occurred, where fine root biomass of the NF was 2.37 times, 3.55 times, 8.12 times, and 7.12 times as much as those of the CK, FH, CF, and OX, respectively. Percentages of original mass lost during the first year of decomposition ranged from 43% to 56% for the FH to 68% to 80% for the NF. Mean annual root decomposition, mortality and production ranged from 8.47 Mg ha -1 a -1 , 8.63 Mg ha -1 a -1 and 9.5 Mg ha -1 a -1 in the NF to 2.50, 2.49 and 2.51 Mg ha -1 a -1 in the CF, ranked as NF > CK > FH > OX > CF. The mean root turnover rate ranged from 1.48 a -1 in the FH to 1.78 a -1 in the NF. On a utilisé des sacs à litière (18 × 18 cm 2 , maille de 0,25 mm) pour déterminer le taux de décomposition des radicelles (< 0,5 mm, 0,5-1 mm, 1-2 mm). Les taux de production moyenne annuelle, de mortalité, de décomposition et de turnover des radicelles ont été calculés par la méthode de « compartment flow ». La biomasse moyenne de radicelles va de 1,49 Mg/ha dans le CF à 4,94 Mg/ha pour le NF ; elle décroît dans l'ordre suivant : NF > CK > FH > OX > CF. On a enregistré des différences significatives de biomasse et nécromasse, selon les saisons dans tous les peuplements (P < 0,05), tandis qu'aucune fluctuation n'a pu être mise en évidence entre années (P > 0,05). Pour tous les peuplements, on enregistre un pic de biomasse de radicelles au début du printemps (mars), les valeurs minimum intervenant au cours d'étés secs ou d'hivers froids. Pour le NF, 59,8 % de la biomasse de radicelles se situe dans la zone superficielle ...

Effect of Stand Age on Fine Root Biomass, Production and Morphology in Chinese Fir Plantations in Subtropical China

“…It is surprising that our results showed different patterns, that fine root biomass was highest in January and lowest in July in all the Chinese fir plantations. Although similar results also had been reported that the minimum value of fine root biomass generally appeared from May to July [40,43]. The fine root biomass dynamics were not only related to the fine root growth, but also the longevity and turnover rate, which merits further investigation.…”

“…The studies on seasonal variations in root biomass had reported that stand ages were consistent with the seasonal variation pattern [40]. Fu et al [34] believed that low temperature is the influencing factor of fine root dynamics.…”

Comparisons of carbon storages in Cunninghamia lanceolata and Michelia macclurei plantations during a 22-year period in southern China

“…Yang et al (2004c) noted that the leaf-litter of Chinese fir possesses higher lignin concentration and lignin/N ratio than that of broad leaf tree. In addition, broadleaved trees may allocate more biomass to their roots, especially the fine roots at the shallow soil horizons, which can fix a greater amount of carbon and transfer more root detritus to the top soil (Yang et al, 2004a(Yang et al, , 2004b.…”

Conversion of a natural broad-leafed evergreen forest into pure plantation forests in a subtropical area: Effects on carbon storage

“…Fine root (< 2 mm) biomass was measured by the sequential core method [49]. On each sampling date, 30 soil cores (1 m in depth) were randomly collected from each forest bimonthly during January 1999-January 2002 using a steel corer (6.8 cm diameter, 1.2 m length).…”

“…We had reported litterfall and fine-root dynamics and soil biological changes on these forests [8,49,51]. The primary objective of this study was to determine if plantations consisting of broadleaved and coniferous species altered the ecosystem C stocks.…”