Effects of adjacent land-use types on the distribution of soil organic carbon stocks in the montane area of central Taiwan

Hsu

et al. 2019

Sci Rep

Riverine dissolved organic carbon (DOC), responsible for riverine productivity, is rarely documented in subtropical small mountainous rivers (SMRs) where high rainfall and steep slopes are the main features. This study investigated the DOC export at eight sites in three Taiwan SMRs to characterize the dynamics and controlling factors of DOC transport. Results showed that the mean DOC concentration of ~0.78 mg L−1 is much lower than the global average of ~5.29 mg L−1. However, the mean DOC yield, ~22.51 kg-C ha−1 yr−1, is higher than the global average of 14.4–19.3 kg-C ha−1 yr−1. Comparing with worldwide rivers from literature, the annual discharge, slope, and SOC (soil organic carbon) are controlling factors as expected, though they influence in different ways. SOC stock likely regulated by elevation-dependent biomes dominate the DOC supply, while slope restrains the DOC generation due to shallow soil depth and fast runoff velocity. However, the abundant discharge flushing this persistent low supply leads to a large DOC export in the SMRs. Furthermore, the DOC dynamics during typhoon periods showed a clockwise hysteresis, suggesting that the DOC is mainly from the riparian zone or downslope area during the rising limb of the hydrograph. This study elucidates the DOC transport in SMRs and provides an atypical yet significant piece of understanding on DOC transport in a global context.

Section: Controlling Factors Of Doc Estimations In Smrscontrasting

confidence: 72%

Section: Controlling Factors Of Doc Estimations In Smrsmentioning

confidence: 99%

Unusual Roles of Discharge, Slope and SOC in DOC Transport in Small Mountainous Rivers, Taiwan

Hsu

et al. 2019

Sci Rep

“…Hence, further research is necessary. Land use change is identified as a cause of SOC losses through erosion and vegetation conversion, and has become a factor contributing to the increase in atmospheric CO 2 concentration [ 13 ]. The characteristics of SOC mineralization varied among different land use types, because the land use change could alter litterfall amount, litter chemistry and soil chemical and physical properties [ 14 ].…”

Section: Introductionmentioning

confidence: 99%

“…Tea ( Camellia sinensis L.) is a perennial evergreen crop with root absorption characteristics and exudates. Tea plantations are artificially managed and gradually form a unique regional ecosystem [ 13 ]. Our previous studies showed that soil properties change with the increasing age of tea plantation, including the content of SOC and nutrient elements; these changed soil properties modify the soil structure and function [ 17 – 19 ].…”

Section: Introductionmentioning

confidence: 99%

Dynamics of soil organic carbon mineralization in tea plantations converted from farmland at Western Sichuan, China

Zhu

Zheng

et al. 2017

PLoS ONE

Climate warming and land use change are some of the drivers affecting soil organic carbon (SOC) dynamics. The Grain for Green Project, local natural resources, and geographical conditions have resulted in farmland conversion into tea plantations in the hilly region of Western Sichuan. However, the effect of such land conversion on SOC mineralization remains unknown. In order to understand the temperature sensitivity of SOC decomposition in tea plantations converted from farmland, this study considered the different years (i.e., 2–3, 9–10, and 16–17 years) of tea plantations converted from farmland as the study site, and soil was incubated for 28 days at 15°C, 25°C, and 35°C to measure the soil respiration rate, amount, and temperature coefficient (Q10). Temperature and land use type interactively affected the SOC mineralization rate, and the cumulative amount of SOC mineralization in all the plots was the largest at 35°C. SOC mineralization was greater and more sensitive to temperature changes in the farmland than in the tea plantations. Compared with the control, tea plantation soils showed lower SOC mineralization rate and cumulative mineralization amount. The 16–17-year-old tea plantation with a low SOC mineralization amount and high SOC content revealed the benefits of carbon sequestration enhancement obtained by converting farmland into tea plantations. The first-order kinetic equation described SOC mineralization dynamics well. Farmland conversion into tea plantations appeared to reduce the potentially mineralizable carbon pool, and the age of tea plantations also had an effect on the SOC mineralization and sequestration. The relatively weak SOC mineralization temperature sensitivity of the tea plantation soils suggested that the SOC pool of the tea plantation soils was less vulnerable to warming than that of the control soils.

“…Consequently, soil nutrients have been estimated at different scales, from field to global by geostatistical techniques [16]. Studies at different scales have determined that the main factors influencing the spatial variability of SOC and STN were soil types [23], climate [24,25], topography [26][27][28], land use patterns [29][30][31], tillage practices [1] and fertilizer application [32].…”

Section: Introductionmentioning

confidence: 99%

Assessing spatial variability of soil organic carbon and total nitrogen in eroded hilly region of subtropical China

Zhang

Shaoyan

et al. 2020

PLoS ONE

The hilly red soil region of southern China suffers from severe soil erosion that has led to soil degradation and loss of soil nutrients. Estimating the content and spatial variability of soil organic carbon (SOC) and soil total nitrogen (STN) and assessing the influence of topography and land-use type on SOC and STN after years of soil erosion control are important for vegetation restoration and ecological reconstruction. A total of 375 topsoil samples were collected from Changting County, and their SOC and STN distributions were studied by using descriptive statistics and geostatistical methods. Elevation, slope, aspect and land-use type were selected to investigate the impacts of natural and human factors on the spatial heterogeneity of SOC and STN. The mean SOC and STN concentrations were 15.85 and 0.98 g kg-1 with moderate spatial variations, respectively. SOC and STN exhibited relatively uniform distributions that decreased gradually from the outside parts to the center of the study area. The SOC and STN contents in the study area were still at moderate and low levels after years of erosion control, which suggests that soil nutrient improvement is a slow process. The lowest SOC and STN values were at lower elevations in the center of Changting County. The results indicated that the SOC and STN contents increased most significantly with elevation and slope due to the influence of topography on the regional natural environment and soil erosion in the eroded hilly region. No significant variations were observed among different slope directions and land-use types.