The Experts below are selected from a list of 189741 Experts worldwide ranked by ideXlab platform
Vincent Chaplot - One of the best experts on this subject based on the ideXlab platform.
-
impact of terrain attributes parent material and Soil Types on gully erosion
Geomorphology, 2013Co-Authors: Vincent ChaplotAbstract:Abstract Gully erosion is a worldwide matter of concern because of the irreversible losses of fertile land, which often have severe environmental, economic and social consequences. While most of the studies on the gullying process have investigated the involved mechanisms (either overland flow incision, seepage or piping erosion), only few have been conducted on the controlling factors of gully wall retreat, an important, if not the dominant, land degradation process and sediment source in river systems. In a representative 4.4 km2 degraded area of the Drakensberg foothills (South Africa) the main objective of this study was to evaluate the relationship between the rate of gully bank retreat (GBR) and parent material, Soil Types and selected terrain attributes (elevation, specific drainage area, mean slope gradient, slope length factor, stream power index, compound topographic index and slope curvatures). The survey of gully bank retreat was performed during an entire hydrological year, from September 2007 to September 2008, using a network of pins (n = 440 from 110 pits). Both the gully contours and pin coordinates were determined, using a GPS with a 0.5 m horizontal accuracy (n = 20,120). The information on the parent material and the Soil Types was obtained from field observations complemented by laboratory analysis, while terrain attributes were extracted from a 20 m DEM generated from 5 m interval contour lines. The average GBR value for the 6512 m of gully banks found in the area was 0.049 ± 0.0013 m y− 1, which, considering bank height and Soil bulk density, corresponded to an erosion rate of 2.30 ton ha− 1 y− 1. There was no significant difference in GBR between sandstone and dolerite and between Acrisols and Luvisols. Despite a weak one-to-one correlation with the selected terrain attributes (r
-
impact of terrain attributes parent material and Soil Types on gully erosion
Geomorphology, 2013Co-Authors: Vincent ChaplotAbstract:Abstract Gully erosion is a worldwide matter of concern because of the irreversible losses of fertile land, which often have severe environmental, economic and social consequences. While most of the studies on the gullying process have investigated the involved mechanisms (either overland flow incision, seepage or piping erosion), only few have been conducted on the controlling factors of gully wall retreat, an important, if not the dominant, land degradation process and sediment source in river systems. In a representative 4.4 km 2 degraded area of the Drakensberg foothills (South Africa) the main objective of this study was to evaluate the relationship between the rate of gully bank retreat ( GBR ) and parent material, Soil Types and selected terrain attributes (elevation, specific drainage area, mean slope gradient, slope length factor, stream power index, compound topographic index and slope curvatures). The survey of gully bank retreat was performed during an entire hydrological year, from September 2007 to September 2008, using a network of pins ( n = 440 from 110 pits). Both the gully contours and pin coordinates were determined, using a GPS with a 0.5 m horizontal accuracy ( n = 20,120). The information on the parent material and the Soil Types was obtained from field observations complemented by laboratory analysis, while terrain attributes were extracted from a 20 m DEM generated from 5 m interval contour lines. The average GBR value for the 6512 m of gully banks found in the area was 0.049 ± 0.0013 m y − 1 , which, considering bank height and Soil bulk density, corresponded to an erosion rate of 2.30 ton ha − 1 y − 1 . There was no significant difference in GBR between sandstone and dolerite and between Acrisols and Luvisols. Despite a weak one-to-one correlation with the selected terrain attributes ( r GBR was the highest at hillslope inflexion points (profile and plan slope curvatures close to zero), in the vicinity of the head cuts and for drainage areas up to 500 m 2 , as both situations experience a high removal rate of the Soil material produced from the gully bank collapse and protecting gullies from laterally retreating. These results could be used to digitally map the more active gully banks for the improved implementation of preventive measures of gully growth, if high resolution DEMs are available. There remained, however, a certain amount of unexplained variability in the data, that further research studies on the mechanisms and associated factors of control of GBR could help to address.
Luuk K Koopal - One of the best experts on this subject based on the ideXlab platform.
-
Soil inorganic carbon stock under different Soil Types and land uses on the loess plateau region of china
Catena, 2014Co-Authors: Wenfeng Tan, Rui Zhang, Hua Cao, Chuanqin Huang, Qinke Yang, Mingkuang Wang, Luuk K KoopalAbstract:The Soil carbon reservoir is the largest carbon reservoir in terrestrial ecosystems and consists of Soil organic and inorganic carbon stocks. Previous studies have mainly focused on the Soil organic carbon (SOC) stock, and limited information is available about the Soil inorganic carbon (SIC) stock. The Chinese Loess Plateau (CLP), which is located in the arid and semi-arid region of China, is an important inorganic carbon reservoir, with a thick Soil layer that is rich in calcium carbonate. However, there are few reports on the SIC stock and its spatial distribution in this region. In the current study, the SIC densities and stocks for various Soil Types and land use patterns were evaluated based on 495 profiles with 2470 Soil samples across the CLP, which were collected from the Chinese Second National Soil Survey. The results showed that in the top 1 m of Soil across the CLP, the average SIC density is 17.04 kg/m(2), and the total SIC stock is approximately 10.20 Pg C (1 Pg = 10(15) g). The SIC stock of the CLP accounts for approximately 18.4% of the total SIC stock throughout China. The average values of the SIC stock in the 0-20, 20-50 and 50-100 cm depths of the CLP are 2.39, 2.92 and 4.89 Pg, respectively. Under different land use patterns, the order of the average SIC density is farmland approximate to grassland > forest in all Soil layers. For the various Soil Types, the SIC density in the 0-100 cm layer is the highest in alkaline Soil and lowest in subalpine meadow Soil, whereas the SIC stock is highest in loessial Soil, eolian sandy Soil and sierozem, and the lowest in subalpine meadow Soil. These differences are largely a result of the area occupied by each Soil type and the climate conditions. The results of this study provide basic information about carbon reservoir in China and contribute to our understanding of the SIC stock on the CLP as it relates to the carbon balance of terrestrial ecosystems. (C) 2014 Elsevier B.V. All rights reserved.
Jacob G Bundy - One of the best experts on this subject based on the ideXlab platform.
-
microbial communities in different Soil Types do not converge after diesel contamination
Journal of Applied Microbiology, 2002Co-Authors: Jacob G Bundy, Graeme I Paton, Colin D CampbellAbstract:Aims: To study the comparative effect of diesel addition and simulated bioremediation on the microbial community in three different Soil Types. Methods and Results: Three different Soils were amended with diesel and bioremediation treatment simulated by addition of nutrients. The progress of bioremediation, and the effect on the indigenous microbial communities, was monitored using microbiological techniques. These included basal respiration, sole carbon source utilization patterns using both a commercially-available substrate set and a set designed to highlight changes in hydrocarbon-utilizing bacteria, and phospholipid fatty acid (PLFA) profiling. The development of active hydrocarbon-degrading communities was indicated by the disappearance of diesel, increases in Soil respiration and biomass, and large changes in the sole carbon source utilization patterns and PLFA profiles compared with control Soils. However, comparison of the relative community structure of the three Soils using PLFA profiling showed that there was no tendency for the community structure of the three different Soil Types to converge as a result of contamination. In fact, they became more dissimilar as a result. Changes in the sole carbon source utilization patterns using the commercially-available set of carbon sources indicated the same result as shown by PLFA profiling. The specially selected set of carbon sources yielded no additional information compared with the commercially-available set. Conclusions: Diesel contamination does not result in the development of similar community profiles in different Soil Types. Significance and Impact of the Study: The results suggest that different Soils have different inherent microbial potential to degrade hydrocarbons, a finding that should be taken into account in impact and risk assessments. Following the development of the microbial community and its recovery is a useful and sensitive way of monitoring the impact and recovery of oil-contaminated Soils.
Erland Baath - One of the best experts on this subject based on the ideXlab platform.
-
phospholipid fatty acid composition biomass and activity of microbial communities from two Soil Types experimentally exposed to different heavy metals
Applied and Environmental Microbiology, 1993Co-Authors: Asa Frostegard, Anders Tunlid, Erland BaathAbstract:The phospholipid fatty acid (PLFA) pattern was analyzed in a forest humus and in an arable Soil experimentally polluted with Cd, Cu, Ni, Pb, or Zn at different concentrations. In both Soil Types, there were gradual changes in the PLFA patterns for the different levels of metal contamination. The changes in the forest Soil were similar irrespective of which metal was used, while in the arable Soil the changes due to Cu contamination differed from those due to the other metals. Several PLFAs reacted similarly to the metal amendments in the two Soil Types, while others showed different responses. In both Soils, the metal pollution resulted in a decrease in the iso-branched PLFAs i15:0 and i17:0 and in the monounsaturated 16:1ω5 and 16:1ω7c fatty acids, while increases were found for i16:0, the branched br17:0 and br18:0, and the cyclopropane cy17:0 fatty acids. In the forest Soil, the methyl branched PLFAs 10Me16:0, 10Me17:0, and 10Me18:0 increased in metal-polluted Soils, indicating an increase in actinomycetes, while in the arable Soil a decrease was found for 10Me16:0 and 10Me18:0 in response to most metals. The bacterial PLFAs 15:0 and 17:0 increased in all metal-contaminated samples in the arable Soil, while they were unaffected in the forest Soil. Fatty acid 18:2ω6, which is considered to be predominantly of fungal origin, increased in the arable Soil, except in the Cu-amended samples, in which it decreased instead. Effects on the PLFA patterns were found at levels of metal contamination similar to or lower than those at which effects on ATP content, Soil respiration, or total amount of PLFAs had occurred.
Ingrid Kogelknabner - One of the best experts on this subject based on the ideXlab platform.
-
land use effects on organic carbon storage in Soils of bavaria the importance of Soil Types
Soil & Tillage Research, 2015Co-Authors: Martin Wiesmeier, Margit Von Lutzow, Peter Sporlein, Uwe Geus, Edzard Hangen, Arthur Reischl, Bernd Schilling, Ingrid KogelknabnerAbstract:Numerous studies have reported substantial changes of Soil organic carbon (SOC) stocks after converting forests into agricultural land and vice versa. However, some studies suggested that agricultural Soils might contain similar amounts of SOC as forest Soils. Losses of SOC induced by cultivation might be overestimated due to shallow Soil sampling and application of inaccurate pedotransfer functions. We investigated the impact of different land uses on total SOC storage down to the subSoil on the basis of 270 Soil profiles in southeast Germany under similar climatic and pedogenic conditions using an equivalent Soil mass (ESM) approach. Land use effects on SOC storage were strongly affected by Soil class, which comprised Soil Types with similar pedogenesis. Both slightly lower (<20%) and even higher SOC stocks were found under cropland compared with forest land for different Soil classes. A comparison of different Soil classes under grassland and forest land also showed no considerable differences of SOC stocks. Soil cultivation may not generally be associated with a strong decline of SOC, as tillage probably promotes the formation of organo-mineral associations and a relocation of SOC with depth may decrease its decomposition. This finding should be taken into consideration when estimating and managing the emission and sequestration of C in Soils. We assume that many studies based on topSoils alone may have underestimated agricultural SOC stocks, particularly when an ESM approach is used. Our results highlight the need for Soil type-specific evaluations in terms of interpreting the effects of land use management on SOC stocks.
