Quantifying the relationship of different grass functional groups to increasing woody plant cover is necessary to better understand the effects of woody plant encroachment on grasslands. This study explored biomass production responses of three perennial grass groups based on photosynthetic pathway and potential canopy height (C4 short-grasses, C3 midgrasses, and C4 midgrasses) to different percent canopy covers of the surrounding deciduous woody legume, honey mesquite (Prosopis glandulosa). Two methods were used to determine mesquite canopy cover, line-intercept and geospatial analysis of aerial images, and both were used to predict production of the three grass groups. Five years of grass production data were included in the mesquite cover/grass production regressions. Two yr had extreme grass production responses, one due to drought and the other to high rainfall. Of the 3 remaining yr, best-fit curves were negative linear for C4 short-grasses and C3 midgrasses and negative sigmoidal for C4 midgrasses using both cover determination methods, although slopes of the curves differed between cover determination methods. C4 midgrasses were more sensitive than the other grass groups to increasing mesquite cover. Loss of production potential when mesquite cover increased from 0% to 35% was 75.5%, 28.7%, and 23.2% for C4 midgrasses, C3 midgrasses, and C4 short-grasses, respectively. Moreover, production potential of C4 midgrasses under no mesquite cover was 3 and 6 times greater than C3 midgrasses or C4 short-grasses, respectively. Spatial settings of the different grass groups in relation to mesquite tree size and size of intercanopy areas provided indirect evidence that the process of mesquite encroachment in the past 50−100 yr may have negatively impacted C4 midgrasses more than the other grass groups. Results suggest that gains in grass production following mesquite treatment would be limited if the system has degraded to where only C3 midgrasses and C4 short-grasses dominate.
Using lightning location data of 9 stations in Hunan Province from 2007 and 2009, we analyze the lightning strength and frequency in Lishui bridge area and have a description of yearly and daily distribution. It shows that Lishui bridge regional lightning presented a mono-peak feature. Lightning mainly occurs from February to September, especially in August. Daily distribution here is extremely uneven. And lightning most happens in 6 a.m. and 4 p.m., which is different from most parts of China. Ground flash density near the bridge is 2.2 times /km2•a. Lightning intensity ranges from 25 kA to 65 kA. Strong lighting at 40-50 kA, even up to 200 kA, is more likely to take place. It has very important significance in choosing the lightning flow of surge protective devices.
DFT calculations have been performed to study the HER mechanism at 1T/2H MoS2 heterostructures. The HER activity along the 1T/2H phase interface is comparable with those at the Mo-edge of 2H MoS2 and the basal plane of 1T MoS2.
In this study, ultrasound was employed to radiate long-chain inulin suspensions in order to obtain some new physicochemical properties. The results showed that ultrasound irradiation effectively improved the viscoelasticity of long-chain inulin samples. The samples achieved the greatest increase in the apparent viscosity and viscoelasticity after 10-min ultrasonic treatment at the intensity of 1734.9 W/cm2. In addition, Fourier transform infrared spectroscopy (FTIR) spectrum analysis revealed that ultrasound could not change the functional groups and molecular structure of long-chain inulin, only effect the hydrogen bonds of long-chain inulin. The results of X-ray diffraction (XRD) indicated that ultrasound also affected the relative crystallinity of long-chain inulin, depending on its intensity and treatment time. Particle size distribution indicated that long-chain inulin with particle size of 100–300 μm formed after ultrasound treatment. The changes in inulin particle size showed that inulin was unfolded by ultrasound treatment at low intensity for a short time and then aggregated with enhanced ultrasound effect. These results suggested that ultrasound treatment can change the physicochemical and structural properties of long-chain inulin, which would facilitate long-chain inulin application in the food industry.
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