Aspect-vegetation complex effects on biochemical characteristics and decomposability of soil organic carbon on the eastern Qinghai-Tibetan Plateau

Abstract

Background Meadows and shrublands are two major vegetation types on the Qinghai-Tibetan Plateau, but little is known about biochemical characteristics and its relation to decomposability of soil organic carbon (OC) under these two vegetation types. The present study was designed to evaluate effects of aspectvegetation complex on biochemical characteristics and decomposability of soil OC. Methods Two hills were randomly selected; both with vegetation being naturally divided into southward meadows and northward shrublands by a ridge, and soils were sampled at depths of 0-15 and 15-30 cm, along contours traversing the meadow and shrubland sites. Particulate (particle size 2-0.05 mm) OC and nitrogen (N), microbial biomass C and N, non-cellulosic sugars, and CuO lignin were analyzed, and OC mineralization was measured for 49 days at 18 and 25°C under laboratory incubation, respectively. Results More than half of soil OC was present as particulate fraction across all samples, indicating the coarse nature of soil organic matter in the region. Averaging over depths, shrublands contained 87.7−114.1 g OC and 7.7−9.3 g N per kg soil, which were 63−78 and 26−31 % higher than those in meadows, respectively. Meanwhile the C/N ratio of soil organic matter was 11.4 −12.3 under shrublands, being 29−40 % higher than that under meadows. Soil OC under meadows was richer in noncellulosic carbohydrates and microbial biomass in the 0-15 and 15-30 cm depths but contained less lignin in the 15-30 cm depth. Ratios of microbiallyto plant-derived monosaccharides and between acid and aldehyde of the vanillyl units were greater in soils under shrublands, showing more abundant microbiallyderived sugars and microbially-transformed ligneous substances in OC as compared to meadow soils. By the end of 49 days' incubation, total CO 2 -C evolution from soils under meadows was 15.0-16.2 mg g −1 OC averaging over incubation temperatures and soil depths, being 27-55 % greater than that under shrublands.

Differential Effects of Natural Palygorskite and its Modified Form on Alleviation of Heavy Metals Toxicity to Tomato Grown in Soil Contaminated with Cd, Pb and Zn

“…Soil pH was determined in 1:2.5 soil/ water suspensions after 0.5 h with a combination pH electrode. Total N and C, available K and P of soil samples were analyzed as described by Zhao et al [19]. The concentration of total heavy metals (Pb, Cd and Zn) in the soil samples were measured after mineralization with HNO 3 and HCl (ratio 1/3) using a Microwave Milestone MLS 1200 [20].…”

Comparison of Soil Organic Matter Transformation Processes in Different Alpine Ecosystems in the Qinghai‐Tibet Plateau

“…Soil represents the largest carbon pool in terrestrial ecosystems, containing at least 1,500 Pg carbon (Jobbagy & Jackson, ), and soil organic matter (SOM) degradation directly affects global climate change (Davidson & Janssens, ). The process of SOM transformation is mainly affected by vegetation type (Zhao et al, ), soil microbes (Bardgett et al, ), and environmental change (Karen et al, ). In different ecosystems, vegetation types and vegetation input can vary, which can then cause differences in soil carbon fractions (Zhang & Zhang, ) and SOM turnover rates (Zhao et al, ).…”

“…The process of SOM transformation is mainly affected by vegetation type (Zhao et al, ), soil microbes (Bardgett et al, ), and environmental change (Karen et al, ). In different ecosystems, vegetation types and vegetation input can vary, which can then cause differences in soil carbon fractions (Zhang & Zhang, ) and SOM turnover rates (Zhao et al, ). Total soil carbon stocks are approximately 40% in forests, 6% in the permafrost, and 28% in grasslands (Dixon et al, ; Huntington, ; Schulp et al, ).…”

Pérdida de suelo por erosión hídrica en la cuenca del lago de Chapala, Michoacán, México

“…El mayor contenido de materia orgánica y nitrógeno total se registró en el bosque de encino y matorral subtropical, con más de 4 y 0.16%, respectivamente. Esto puede deberse a la velocidad de mineralización del carbono orgánico, más lento en áreas con vegetación natural en comparación con aquellos suelos cuya vegetación son pastizales o de uso agrícola (Zhao et al, 2014).…”

“…El pH de los suelos osciló entre 6.6 y 7.1, siendo los ocupados por pastizales los que registraron el menor valor y donde se presenta la agricultura de riego los de valor más alto. Los suelos con pH bajo se pueden deber al retorno de los nutrientes y acidificación por la densidad de raíces que contiene el pastizal (Zhao et al, 2014).…”