Biomedical subjects

Wenbin Guan

Publications and source records attributed to Wenbin Guan.

4 recordsLinked to original sources

PubMed2003

[Advances in studies on the structure of farmland shelterbelt ecosystem].

The ecological function of farmland shelterbelt system is determined by its structure. The spatio-temporal structure is a key aspect in related researches, which is very necessary to study the integrity, stability and durability of shelterbelt modules. In this article, the researches on the structure of farmland shelterbelt ecosystem were reviewed from the four scales of tree structure, shelterbelt structure, shelterbelts network and landscape structure. The principles, methods and productions of each scale were summarized, and the prospects were also discussed. Dynamic simulation of tree growth process in shelterbelts could be conducted by the theory of form and quality structure of tree and by fractal graphics, which were helpful to study the mechanism of individual trees and belts based on photosynthetic and transpiration mechanism of individual trees. The mechanism model of shelterbelt porosity should be conducted, so that, the sustainable yield model of shelterbelt management could be established, and the optimized model of shelterbelt networks with multi-special and multi-hierarchical structure could also be formed. Evaluating the reasonability, stability and durability of shelterbelt landscape based on the theories and methods of landscape ecology was an important task in the future studies.

Agriculture↗

PubMed2002

[Improvement and application of digitized measure on shelterbelt porosity].

Based on the lots of investigation on farmland shelterbelts, we used digital camera to take pictures of shelterbelt and apply CIAS software to improve "digital image processing" for determining shelterbelt porosity so as to thoroughly analyze the rule of porosity in farmland shelterbelts. Compared with the old digital image processing, the improved method possesses high accuracy, and it is more economical and more convenient to apply. The relationship between porosity of shelterbelts (beta) and relative clear bole height (x) can be expressed as beta = 0.672x0.469 (r = 0.9851, r0.01 = 0.4073, 0 < or = beta < or = 1) in the leaf period; and beta = 1.0681x0.4304 (r = 0.9763, r0.01 = 0.4073, 0 < or = beta < or = 1) in the defoliation period. beta varies with the stand age (a), taking the form of parabola, which can be expressed as beta = 0.0009a2 - 0.0364a + 0.6828 (0 < or = beta < or = 1). Porosity at cross-section of shelterbelt can be used as an auxiliary index to evaluate the structure of belts. The calculation method of shelterbelt porosity of mixed shelterbelt can be expressed as beta = (beta 1n1 + beta 2n2)/(n1 + n2). Among the popular, willow and elm pure shelterbelts with same disposition, popular shelterbelt structure is the best, with beta PPP < beta SSS < beta UUU, while the triangle disposition is better than the rectangle one among the same tree species. UPPU and SPPS of mixed structure have the optimal effect in popular-willow-elm mixed shelterbelts.

Trees↗

PubMed2002

[Fractal structure of Abies fabri, dominant tree species in dark coniferous forest at the upper reach of Yangtze River].

Based on the theory of fractal geometry, branching patterns of primitive Abies fabri in the dark coniferous forest ecosystem at the upper reach of Yangtze River were studied. The results showed that the maximum crown width was appeared at inferior 20% of the crown height, and its volume could be simulated by the combination of a round table and a cone. The surface of the crown and their branching patterns of Abies fabri had the common typical fractal characters, the fractal dimensions (FD) were 2.3232 and 1.8119, and the correlation coefficient was 0.99.

Abies↗

PubMed2002

[Plot analysis in the dark coniferous ecosystem using GPS and GIS techniques].

It is generally difficult to survey in primary forests located on high-altitude region. However, it is convenient to identify and to recognize plots accompanied by GPS and GIS techniques, which can also display the spatial pattern of arbors precisely. Using the method of rapid-static positioning cooperated with tape-measure, it is concluded that except some points, the positioning was relatively precise, the average value of RMS was 2.84, variance was 2.96, and delta B, delta L, and delta H were 1.2, 1.2, and 4.3 m with their variances being +/- 0.6, +/- 1.1, and +/- 21.1, respectively, which could meet the needs of forestry management sufficiently. Accompanied by some other models, many ecological processes under small and even medium scale, such as the dynamics of gap succession, could also be simulated visually by GIS. Therefore, the techniques of "2S" were patent for forest ecosystem management under the fine scale, especially in the area of high altitude.

Altitude↗