Abstract
BackgroundSoil organic carbon (SOC) stocks can be altered through reforestation and cropping. We estimated the effects of land use on SOC stocks after natural deciduous forests replaced by crops and coniferous plantations by examining the vertical distribution of SOC stocks at different depth intervals in an adjacent Oolong tea (Camellia sinensis L.) plantation, Moso bamboo (Phyllostachys pubescens) forest, Japanese cedar (Cryptomeria japonica) forest, and Taiwania (Taiwania cryptomerioides) forest in central Taiwan. The main soil characteristics, soil nitrogen (N) content, and soil carbon to nitrogen (C/N) ratio were also determined.ResultsDifferent land uses resulted in significantly higher bulk density, lower cation exchange capacity, SOC, soil N, soil C/N ratio, and SOC stocks in croplands compared to forestlands. Due to the long-term application of chemical fertilizers, a significantly lower soil pH was found in the tea plantation. Croplands had a lower soil C/N ratio because of less C input into the soil and a higher mineralization rate of organic carbon during cultivation. Similar SOC stocks were found in Taiwania and Japanese cedar forests (148.5 and 151.8 Mg C ha−1, respectively), while the tea plantation had comparable SOC stocks to the bamboo forest (101.8 and 100.5 Mg C ha−1, respectively). Over 40% of SOC stocks was stored in croplands and over 56% was stored in forestland within the upper 10 cm of soil.ConclusionsConiferous plantations can contribute to a higher SOC stock than croplands, and a significant difference can be found in the top 0–5 cm of soil.Electronic supplementary materialThe online version of this article (doi:10.1186/s40529-016-0147-5) contains supplementary material, which is available to authorized users.
Highlights
Soil organic carbon (SOC) stocks can be altered through reforestation and cropping
To estimate the difference in SOC stocks among the local land uses of the selected area, we identified four land-use types as study sites: conventionally tilled cropland with Oolong tea (Camellia sinensis L.), conventionally tilled cropland with Moso bamboo (Phyllostachys pubescens), and two coniferous plantations with Japanese cedar (Cryptomeria japonica) and Taiwania (Taiwania cryptomerioides)
The results indicate that cultivation of croplands could lead to a lower CEC, less SOC, and a higher bulk density (BD) compared to coniferous plantations and a significant lower soil pH in tea plantation; these findings are in agreement with those of Lugo et al (1986) and van Straaten et al (2015) for estimating the effects of land-use change in subtropical soils and tropical forests
Summary
Soil organic carbon (SOC) stocks can be altered through reforestation and cropping. We estimated the effects of land use on SOC stocks after natural deciduous forests replaced by crops and coniferous plantations by examining the vertical distribution of SOC stocks at different depth intervals in an adjacent Oolong tea (Camellia sinensis L.) plantation, Moso bamboo (Phyllostachys pubescens) forest, Japanese cedar (Cryptomeria japonica) forest, and Taiwania (Taiwania cryptomerioides) forest in central Taiwan. Land-use changes can accelerate SOC stock loss through erosion or vegetation conversion, and SOC stocks in surface soil and subsoil can change after native forest is converted to agricultural systems (Smith et al 2002; Chen et al 2004; Schulp et al 2008; Fu et al 2010; Don et al 2011). Soil carbon content is known to decline once the natural forest has been cleared for croplands and plantations. Estimates of SOC stocks decline indicated by various researchers worldwide include an SOC stocks decrease of 13% from native forest to plantation and 42% from native forest to cropland (Guo and Gifford 2002), a decrease of 30% due to the conversion of forests to cultivated lands (Murty et al 2002), and a 25 and 30% SOC loss for the conversion of primary forest to cropland and perennial crops, respectively (Don et al 2011). C can be restored in the mineral soil after cropland reverts to natural vegetation or is reforested to perennial vegetation (Post and Kwon 2000)
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