Biomedical subjects

Zhenxi Shen

Publications and source records attributed to Zhenxi Shen.

3 recordsLinked to original sources

PubMed2005

[Rainffall interception model of forest canopy: a preliminary study].

Canopy interception is an important hydrological process in forest ecosystem, and its modelling is of significance to understand and estimate the rainfall interception by the canopy. In this paper, a canopy rainfall interception model was established by dividing a rain incident into a set of short period, calculating the rainfall distribution intercepted by the canopy, and educing the process of the rain incident. This model considered the effects of the dryness of canopy and trunk on the evaporation from wet canopy and trunk during one rain incident, and introduced two factors, leaf area index (LAI) and surface area of trunk per unit area of ground (SAI), when computing the evaporation. The application of the model to simulate the rainfall interception process in a Larix principis-rupprechtii plantation in Guyuan, south Ningxia Hui autonomous region of China showed that the simulated and measured throughfall were identical, and the absolute deviation between simulated and measured results was within +/- 1 mm. But, when the precipitation was smaller than 6 mm, the simulated throughfall was lower than the measured one. The values of simulated stemflow were lower than the measured values, and the relative deviation between simulated and measured values was smaller when the precipitation was larger. The process of throughfall in the forest was also simulated, with the results fitted well to the measured one.

Ecosystem↗

PubMed2003

[Clonal growth of stoloniferous herb Potentilla anserina on degraded and non-degraded alpine meadow soil].

The clonal growth of Potentilla anserina on degraded and non-degraded Kobresia humilis meadow soil was studied by a transplanting experiment in the field. No significant differences in numbers of stolons, height, and leave size per mother ramet were observed between the two soils, but the numbers of leaves per mother ramet, length and width of stolon, and spacer length were significantly different. There were more leaves per mother ramet, longer stolon and spacer, and wider stolon on degraded soil, where available nutrient was poor than in non-degraded soil. Under degraded alpine meadow soil condition, the clonal plant species might produce much more photosynthetic product to support stolon growth by the increase of leave numbers per mother ramet, and the longer and wider stolon could intensify the foraging ability of the mother ramet that would benefit to daughter ramet. Both mother and daughter ramet of Potentilla anserina invested much more biomass to their underground part (root system) in non-degraded soil to increase the survival rate of daughter ramet.

Biomass↗

PubMed2002

[Analysis of formation causes of grassland degradation in Maduo County in the source region of Yellow River].

Natural and artificial factors of grassland degradation in Maduo County in source region of Yellow River were analyzed in this paper. The results showed that overgrazing was the major reason for grassland degradation. Compared with historical average, annual temperature and precipitation in Maduo had an obvious rise since the end of 1980s. Temperature rise concentrated in winter, and precipitation rise concentrated in spring and summer. Therefore, the change in water and heat condition was advantageous to grass growth there. Maduo was a county totally dependent on stock raising, and enlarging livestock population was the only choice for economic development. Together with the pressure of population growth and local Tibetan's traditional value, the number of livestock had been increased continuously, and finally reached summit in the end of 1970s. Since then, the grassland had been kept in the state of overgrazing and degradation, which also created favorable condition for the invasion of pikas, and thus sped up the process of degradation.

Animals↗