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Fresh tree root decomposition induced by tillage is an important source of soil nutrients in agroforestry systems. Here we examined the effects of tree species, root size and soil N enrichment on fresh root decomposition under laboratory conditions. Fresh roots with two diameters (<2 and 2–5 mm) of Populus euramericana cv. ‘N3016’ (poplar) and Pinus(More)
Afforestation of marginal agricultural land has been considered to be an effective measure to sequester atmospheric CO2. In this study, we adopted the volume- and mass-based methods to investigate the changes in soil organic C and total N stocks in 100 cm depth following afforestation of marginal agricultural land using a chronosequence of poplar (Populus(More)
Surface (0–15 cm) soil samples were collected from a semi-arid, sandy grassland in Keerqin Sandy Lands, Northeast China to study changes in soil microbial and chemical properties after five consecutive years of nitrogen (N) and phosphorus (P) additions. Nitrogen and P additions and their interactions negligibly affected soil organic carbon and total N(More)
Nitrogen (N)-fixing species have a function to enrich N in soil. Mixing N-fixing shrub species into poplar stands can be assumed as a measure to increase productivity while improving soil fertility. To verify this assumption and to understand the temporal influences of N-fixing shrub species mixed into poplar plantations on soil fertility, we investigated(More)
A field experiment was conducted to evaluate the influences of long-term applications of organic amendments and chemical fertilizers on nitrous oxide (N2O) emissions from Mollisols in northeast China and to relate soil N2O fluxes to soil moisture and temperature. A closed-chamber method was used to determine soil N2O flux during the maize growing season in(More)
Taking 5-, 10-, 15-, and 20 years old poplar (Populus euramericana cv. "N 3016") shelterbelts in Jianping County, Liaoning Province as test objects, the effects of establishing shelterbelts on the farmland soil microbial biomass carbon and nitrogen, and microbial activity were evaluated. After the establishment of shelterbelts, the concentrations of organic(More)
BACKGROUND Soil organic carbon (SOC) is fundamental for mitigating climate change as well as improving soil fertility. Databases of SOC obtained from soil surveys in 1981 and 2011 were used to assess SOC change (0-20 cm) in croplands of Heilongjiang Province in northeast China. Three counties (Lindian, Hailun and Baoqing) were selected as typical croplands(More)
Phytochemical investigation of the leaf of Ilex centrochinensis led to the isolation and characterization of four flavans, one flavanone (5), and one flavone (6), including a new compound whose structure was elucidated as (2S)-5,3',4'-trihydroxy-7-methoxyflavan (1) and a new natural product whose structure was elucidated as(More)
Grassland conversion to cropland (GCC) may result in loss of a large amount of soil organic carbon (SOC). However, the assessment of such loss of SOC still involves large uncertainty due to shallow sampling depth, soil bulk density estimation and spatial heterogeneity. Our objectives were to quantify changes in SOC, soil total nitrogen (STN) and C:N ratio(More)
Four new alkenes (1-4), and six known alkenes (5-12) were isolated from Murraya koenigii (L.) Spreng. Their structures were elucidated on the basis of spectroscopic analyses and references. Compounds (1-12) were evaluated for antioxidative activities. Among them, compounds 1, 2, 4, and 7 exhibited significant antioxidative activities using(More)