Dissolved soil organic carbon and nitrogen were affected by conversion of native forests to plantations in subtropical China

Abstract

. 2010. Dissolved soil organic carbon and nitrogen were affected by conversion of native forests to plantations in subtropical China. Can. J. Soil Sci. 90: 27Á36. To better understand the impact of converting native forests to intensively managed plantations on soil carbon (C) and nitrogen (N) dynamics in subtropical China, we examined the seasonal patterns of water-soluble organic C (WSOC) and N (WSON) concentrations in soils in Chinese chestnut (Castanea mollissima Blume) (CF) and bamboo (Phyllostachys praecox C.D. Chu & C.S. Chou) plantation forests (BF) and adjacent native evergreen broadleaf forests (NF) in Ling-long Mountain, Zhejiang Province, China. The plantations were disturbed through surface soil removal and were fertilized and/or mulched, from which economic products (such as nuts and bamboo shoots) were annually harvested. We found that WSOC and WSON had large seasonal variations and were lower in the warmer than in the colder season. Average WSOC concentrations followed the order of BF (58.6)!NF (35.1)!CF (18.1 mg C kg Á1 ), a pattern mainly caused by mulching in BF in winter and the removal of surface soil in CF. Soil total C and N followed the order of BF !NF !CF. The extensive inorganic and organic fertilizer application in BF caused WSON concentrations to be 21 and 14 times higher than those in NF and CF, respectively. Conversion of native forests to plantations lowered soil WSOC:WSON and soil C:N ratios. The seasonal dynamics of WSOC:SOC (soil organic C) and WSON/TN ratios followed the same patterns of WSOC and WSON, respectively. The impacts of forest types on WSOC/SOC ratio, which is a measure of the quality of organic matter, were dependent on seasonal changes of management practices and/or tree growth. Nevertheless mean annual WSON/TN ratios of BF and CF were 2 and 12 times that of NF, indicating that a greater proportion of the total soil N pool became solubilized in the intensively managed plantations. We conclude that land-use conversion and associated management practices had a profound impact on WSOC, WSON, and total C and N concentrations in the studied forest soils in subtropical China.Key words: Forest management, water-soluble organic C, water-soluble organic N, WSOC/WSON ratio Wu, J.-S., Jiang, P.-K., Chang, S. X., Xu, Q.-F. et Lin, Y. 2010. La transformation des foreˆts naturelles en plantations dans la Chine subtropicale affecte le carbone et l'azote dissous dans le sol. Can. J. Soil Sci. 90: 27Á36. Pour mieux comprendre les conse´quences de la conversion des foreˆts naturelles en plantations intensives sur la dynamique du carbone (C) et de l'azote (N) dans le sol de la Chine subtropicale, les auteurs ont e´tudie´la variation saisonnie`re de la concentration du C hydrosoluble dans le sol (CCHS) et du N hydrosoluble dans le sol (CNHS) dans les foreˆts cultive´es de chaˆtaignier de Chine (Castanea mollissima Blume) (FC) et de bambou (Phyllostachys praecox C.D. Chu & C.S. Chou) (FB) ainsi que dans les foreˆts naturelles (FN) de conife`res latifolie´s adjacentes du mont Ling-long,...

Effects of Nitrogen Deposition on Soil Dissolved Organic Carbon and Nitrogen in Moso Bamboo Plantations Strongly Depend on Management Practices

“…It is known that the concentrations of DOC and DON are mainly derived from ground litter, root exudates, soil humus, soil microbial biomass, and rainfall leaching [26]. Wu et al [27] found that excessive consumption by microbial populations would decrease the DOC and DON in seasons with high temperature and high precipitation, which is consistent with our result. DOC and DON are important carriers of C and N loss in forest soil [28,29].…”

“…Our previous study on this site showed that IM significantly increased soil MBC [21], indicating an increase in DOC consumption, which might greatly contribute to lower DOC concentrations in the IM plots than in the CM plots. Changed nutrient dynamics caused by management practices can also affect DOM concentrations between the native forests and plantations [27]. Long-term fertilization in the IM plots induced the loss of soil organic C and N and greatly decreased the chemical activity of the soil [20].…”

Effects of temperature on the composition and diversity of bacterial communities in bamboo soils at different elevations

“…It is distributed from low-to high-mountain regions at approximately 1800 m above sea level (a.s.l.). Management practices for increasing bamboo production, including regular removal of understory vegetation, tillage, and fertilizer application, can increase the soil CO 2 efflux (Liu et al, 2011) and watersoluble organic N concentration (Wu et al, 2010). However, these management practices can lower the microbial functional diversity (Xu et al, 2008).…”

Soil Organic Carbon Content and Microbial Functional Diversity Were Lower in Monospecific Chinese Hickory Stands than in Natural Chinese Hickory–Broad-Leaved Mixed Forests

“…In the soil organic carbon, decomposition increases the relative abundance of alkyl C [49,50], which in turn increases the proportion of hydrophobic C [51,52]. A high proportion of aliphatic C indicates simpler molecular structures that are more readily decomposed, whereas a high proportion of aromatic C contents indicates complicated structures that are more resistant to decomposition.…”