The project LIFE09 ENV/IT/078 Managing forests for multiple purposes: carbon, biodiversity and socio-economic wellbeing (ManFor C.BD.), among other objectives, is aimed to evaluate carbon sequestration taking into account forest management for conserving and enhancing carbon stocks, and increase carbon sequestration. The first step to do that is modelling and mapping spatial variability of soil organic carbon to assess the ability of soil to sequestrate biologic carbon. Conventional methods for soil organic carbon (SOC) determination are based on laboratory analyses and are costly and time consuming. Soil spectral reflectance is an alternative approach for SOC determination and has the advantage to be rapid, non-destructive and cost effective. The paper was aimed at: 1) quantifying SOC using laboratory-based soil visible, near infrared (Vis-NIR) reflectance spectroscopy and 2) mapping SOC using a geostatistical approach. The study area was a forest beech (332.000 m2) located in southern Italy at a mean elevation of about 1,180 m a.s.l. Soils mainly are coarse-textured, relatively young (Entisol and Inceptisol) and from poorly to moderately differentiated. They are strongly dependent on the nature of the parent rock (Paleozoic granitoid rocks) and their depth range from shallow to moderately deep and soil profiles are characterized by A-Bw-Cr and/or A-Cr horizons. The upper A horizon has an high accumulation of organic matter (umbric epipedon) and a very dark brown colour. Soil samples were collected at 235 locations within the study area using a metallic core cylinder with a diameter of 7.5 cm and a height of 20 cm. Each sample was oven dried at 45° for 48 hours and sieved at 2 mm and was used before for spectroscopic measurements and then analysed to determine organic carbon content. The Vis-NIR reflectance of soil samples was measured in laboratory, under artificial light, using an ASD FieldSpec IV 350 - 2500 nm spectroradiometer (Analytical Spectral Devices Inc., Boulder, Colorado, USA), while SOC was determined using a TOC-L analyzer (Shimadzu Corporation, Kyoto, Japan). The partial least squared regression (PLSR) analysis was used to establish the relationships between spectral reflectance and OM content. PLSR was performed on 2/3 of the soil samples. The optimum number of factors to retain in the calibration models were determined by cross validation. The models were independently validated using data from the remaining soil samples. Results revealed a high level of agreement between measured and predicted values with coefficients of determination. Finally, ordinary kriging was used to map SOC in the study area.
Soil organic carbon mapping of a forest beech in southern Italy using laboratory-based Vis-NIR spectroscopy
Buttafuoco G;Conforti M;Froio R;Matteucci G
2014
Abstract
The project LIFE09 ENV/IT/078 Managing forests for multiple purposes: carbon, biodiversity and socio-economic wellbeing (ManFor C.BD.), among other objectives, is aimed to evaluate carbon sequestration taking into account forest management for conserving and enhancing carbon stocks, and increase carbon sequestration. The first step to do that is modelling and mapping spatial variability of soil organic carbon to assess the ability of soil to sequestrate biologic carbon. Conventional methods for soil organic carbon (SOC) determination are based on laboratory analyses and are costly and time consuming. Soil spectral reflectance is an alternative approach for SOC determination and has the advantage to be rapid, non-destructive and cost effective. The paper was aimed at: 1) quantifying SOC using laboratory-based soil visible, near infrared (Vis-NIR) reflectance spectroscopy and 2) mapping SOC using a geostatistical approach. The study area was a forest beech (332.000 m2) located in southern Italy at a mean elevation of about 1,180 m a.s.l. Soils mainly are coarse-textured, relatively young (Entisol and Inceptisol) and from poorly to moderately differentiated. They are strongly dependent on the nature of the parent rock (Paleozoic granitoid rocks) and their depth range from shallow to moderately deep and soil profiles are characterized by A-Bw-Cr and/or A-Cr horizons. The upper A horizon has an high accumulation of organic matter (umbric epipedon) and a very dark brown colour. Soil samples were collected at 235 locations within the study area using a metallic core cylinder with a diameter of 7.5 cm and a height of 20 cm. Each sample was oven dried at 45° for 48 hours and sieved at 2 mm and was used before for spectroscopic measurements and then analysed to determine organic carbon content. The Vis-NIR reflectance of soil samples was measured in laboratory, under artificial light, using an ASD FieldSpec IV 350 - 2500 nm spectroradiometer (Analytical Spectral Devices Inc., Boulder, Colorado, USA), while SOC was determined using a TOC-L analyzer (Shimadzu Corporation, Kyoto, Japan). The partial least squared regression (PLSR) analysis was used to establish the relationships between spectral reflectance and OM content. PLSR was performed on 2/3 of the soil samples. The optimum number of factors to retain in the calibration models were determined by cross validation. The models were independently validated using data from the remaining soil samples. Results revealed a high level of agreement between measured and predicted values with coefficients of determination. Finally, ordinary kriging was used to map SOC in the study area.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
