Chinese Fir Forest Research Articles

Carbon and nitrogen pools in Chinese fir and evergreen broadleaved forests and changes associated with felling and burning in mid-subtropical China

A Chinese fir forest ( Cunninghamia lanceolata, CL) and a secondary evergreen broadleaved forest (BF) located in Fujian Province, south-eastern China, were examined before clear-cutting to compare their ecosystem carbon and nitrogen pools (above- and below-ground tree, understorey vegetation and forest floor biomass + 0–100 cm mineral soil layer). The ecosystem pools of C and N in the CL before clear-cutting were 257 Mg ha −1 and 8605 kg ha −1, respectively. The corresponding values for the BF were 336 Mg ha −1 of C and 10,248 kg ha −1 of N. For the two forests, most of the C was in the trees, whereas most of the N pool was in the soil. C and N pools in understorey vegetation and forest floor were small in the two forests (about 2% of ecosystem pools). During clear-cutting, 117 Mg ha −1 C and 307 kg ha −1 N in stem wood with bark and coarse branches (>2 cm) were removed from the CL compared to 159 Mg ha −1 C and 741 kg ha −1 N from the BF. Two days after slash burning, C removal from logging residues (including forest floor material) was estimated at 10 Mg ha −1 for CL and 23 Mg ha −1 for BF, and N removal was 233 and 490 kg ha −1 in the CL and BF, respectively. Compared with the pre-burn levels in the CL, contents of topsoil organic C and total N 2 days after burning were reduced by 17 and 19%, respectively. In the BF, the corresponding proportions were 27% (C) and 25% (N). Our results indicate that clear-cutting and slash burning had caused marked short-term changes in ecosystem C and N in the two forests. How long these changes will persist needs further study.

Comparative Study of Selected Soil Properties Following Introduction of Broad‐Leaf Trees into Clear‐Felled Chinese Fir Forest

After clear‐cutting of the first generation Chinese fir (Cunninghamia lanceolata) planted forest, five management models, viz. mixture of Chinese fir and Kalopanax septemlobus (MCK), mixture of Chinese fir and Alnus cremastogyne (MCA), pure Kalopanax septemlobus stand (PKS), pure Alnus cremastogyne stand (PAS), and pure Chinese fir stand (PCS), were established in 1983. The effects of these management models on soil were evaluated by measuring physico‐chemical parameters and soil solution chemistry 20 years after planting. Both broadleaf monocultures and mixtures of broadleaf and conifer exerted a favorable effect on soil fertility. The concentrations of the mainly atmospherically derived ions, including SO4 2−, Cl−, Na+, and Mg2+, were significantly higher under conifer than under broadleafs and under mixtures of broadleaf and conifer. Whereas the concentrations of ions that were mainly controlled within system processes such as K+ and NH4 + varied little among various management models, with the exception of NO3 −, which was significantly higher below PAS than below the others. The concentrations of H+ and Al3+ were also highest under the conifer. In addition, the aerosol sulfate and SO2 deposition did not result in a net loss of base cations (on an area basis) from the broadleaf monocultures and mixtures of broadleaf and conifer. However, slight decreases in forest floor bases were observed under the conifer. The observed evidence from this study also suggests that the principal factor for forest soil acidification may be the N deposition and nitrification of NH4 +, but not S deposition in this region.

Changes in soil quality due to introduction of broad‐leaf trees into clear‐felled Chinese fir forest in the mid‐subtropics of China

Abstract. After clear‐felling of a first generation Chinese fir (Cunninghamia lanceolata) forest, mixed stands of Chinese fir and Michelia macclurei (a broadleaf tree) (MCM), pure M. macclurei stands (PMS) and pure Chinese fir stands (PCS) were established in 1983. The effects on soil were evaluated 20 years after planting by measuring physicochemical, microbiological and biochemical parameters. Both broadleaf monoculture and mixtures of broadleaf and conifer exerted a favourable effect on soil fertility. A soil quality index (SQI) decreased in the order: PMS (0.62) > MCM (0.57) > PCS (0.41). Improvement in soil quality, enhanced biological activity and forest productivity demonstrated that mixed stands are an effective measure to maintain sustainable forest productivity, as well as to control soil degradation under successive stands of Chinese fir. In addition, since the microbiological and biochemical parameters measured were sensitive to the forest management, they may be potential indicators for assessing the sustainability of different management systems. The results also showed that total organic carbon, cation exchange capacity and microbial biomass carbon are effective indicators of the improvement or deterioration of soil quality under forest.

Changes in soil quality due to introduction of broad-leaf trees into clear-felled Chinese fir forest in the mid-subtropics of China

Changes in soil quality due to introduction of broad-leaf trees into clear-felled Chinese fir forest in the mid-subtropics of China

WATER-SOLUBLE ORGANIC MATTER IN SOIL UNDER CHINESE FIR AND MASSON PINE FOREST

In order to understand the behavior of water soluble organic matter (WSOM) in soil under different types of forest, soil samples from twenty sites were sampled and analyzed for each forest in the area of Huzhou, China. Each sample was extracted with both cool water (25°C) and hot water (100°C). Without exception, hot water soluble organic carbon (HWSOC) was more than cool water soluble organic carbon (CWSOC). Chinese fir forest soil contained 1.49 times more CWSOC and 1.34 times more HWSOC than did the masson pine forest soil. The CWSOC and HWSOC in soil under Chinese fir forest account for 1.11% and 1.60% of total soil organic carbon (TSOC), and 0.70% and 1.19% under masson pine forest soil, respectively. CWSOC under Chinese fir forest was closely related to SOM and microbial biomass carbon (MBC) (correlation coefficients were 0.474* and 0.482* respectively), HWSOC, however, has little to do with SOM, MBC and soil enzymatic activities. HWSOC under masson pine forest was generally associated with SOM, MBC and sucrase, urease and protease (correlation coefficients were 0.511*, 0.510*, 0.541*, 0.418*, 0.356, respectively), but CWSOC was only closely related to sucrase (0.560*) and protease (0.581* *). It is concluded that higher amount of WSOC under Chinese fir forest is not good for soil chemical and biological properties.