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[Objective] In order to explore the relationship between the windbreak direction and the prevailing wind erosion direction in the black soil region of Northeast China. [Methods] The basic characteristics of the windbreak in the study area were obtained by remote sensing interpretation and field survey, and the angle of intersection between the windbreak direction and the prevailing wind erosion direction, that is, the wind direction declination angle, was calculated and analyzed by combining the wind speed and wind direction data of 43 meteorological stations in the study area. [Results] The westerly wind in Mengdong black soil sub-region accounted for a large proportion, the wind direction was more concentrated, the prevailing wind erosion direction dominance was strong, the wind direction in the Songnen black soil sub-region was scattered, and the prevailing wind erosion direction dominance was weak. Average windbreak density Songnen black soil sub-area > Mengdong black soil sub-region; The windbreak direction accounted for the largest proportion in the Songnen black soil sub-area was the N-S trend windbreak direction, and there was no obvious regularity in the Mengdong black soil sub-region. In the study area, the proportion of wind declination angle 30° was 70.40%, and the wind protection effect was poor. [Conclusion] The direction of a large number of windbreak in the study area is oblique to the prevailing wind erosion direction, and the protective effect is poor. The results of this study have important reference value for understanding the density and trend of existing windbreak belts, and for further construction and transformation of windbreak.

To understand the relationship between plant community succession and soil nutrient dynamics is crucial in intervening vegetation succession. This paper reported the results from a study carried out in a forest-steppe zone on the Loess Plateau, with emphasis on the vegetation characteristics and soil nutrient dynamics duringvegetation restoration on abandoned farmlands of this area. The results showed that under zonal habitat conditions, natural vegetation succession would turn toward the original vegetation communities, but the expected shrub or trees communities didn't occur after 40 approximately 50 years, and Stipa bungeana, Artemisia sacrorum, Bothriochloa ischaemun, Stipa grandis and Lespedeza davurica communities were still the widely distributed communities. Vegetation restoration had a significant effect on soil nutrient dynamics. In general, soil nutrient contents increased with restoration time, and extremely significant changes occurred in soil organic matter, total N, available N, and available K (P< 0.001),while only significant changes in available P (0.05 < P < 0.01) and no significant change in total P (P > 0.05). Moreover, the changes were also found in soil profile. Statistical analysis showed that from surface layer (0 approximately 20 cm) to deeper layer (to 60 cm), extremely significant changes occurred in soil organic matter, total N, available N, available K and available P (P < 0.001), and significant change in total P (P< 0.05). Soil nutrients intended to accumulate in surface layer. Further linear correlation analysis showed that soil organic matter, total N, available N and available K were significantly correlated each other ( P< 0.001), but didn't show correlation with soil total P and available P.

The ALMANAC model was validated in a drought-stressed year and in a period from 1989 to 1998 at different sites of Texas to evaluate its ability in simulating maize and sorghum yields at different spatial scales and to extend its application range. There were 11 sites for maize and 8 sites for sorghum in plot-size simulations, and 9 counties for maize and sorghum in county level simulations. The model showed similar accuracy in simulating both plot-size and county level mean grain yields. It could also simulate single-year yields under water-limited climatic conditions for several sites and mean county yields of maize and sorghum, and had small CV values of mean yields for a long-term prediction. The mean error was 8.9% for sorghum and 9.4% for maize in field scale simulations, and was only 2.6% for maize and-0.6% for sorghum in county level mean yield simulations. Crop models often require extensive input data sets to realistically simulate crop growth. The development of such input data sets is difficult for some model users. The soil, weather, and crop parameter data sets developed in this study could be used as the guidelines for model applications in similar climatic regions and on similar soils.

Objective: To study the effects of the bone matrix gelatin and composite of bone morphogenetic protein and fibrin glue (BMP-FG) on the repair of thyroid cartilage defect., Method: Full-thickness defects measuring 0.4 cm x 0.4 cm were created in four sections in thyroid cartilages of 20 adult dogs. The defects were divided into 4 groups by the sections they in. Group A was empty group, without implant; Group B were repaired by implanted with hydroxylapatite; Group C with bone matrix gelatin (containing BMP); Group D with bone morphogenetic protein-fibrin glue composite. The animals were killed separately at 2, 4, 12 weeks after operation. The effects of repair were analyzed by routine histological examination and electron microscope., Result: In the BMP-FG implanted group, the result showed complete absorption of the implant and substitution by new-formed cartilage and bone. The defects in the BMG group regenerated less cartilage and bone, the inflammation was sever. The gross appearance and histological features of HA group were similar to the empty group., Conclusion: Both BMP-FG and BMG can induce cartilage and bone regeneration to repair the defect of thyroid cartilage. BMP-FG has a better effect.

Vegetation cover and land management are the main limiting factors of soil erosion, and quantitative evaluation on the effect of different vegetation on soil erosion is essential to land use and soil conservation planning. The vegetation cover and management factor (C) in the universal soil loss equation (USLE) is an index to evaluate this effect, which has been studied deeply and used widely. However, the C factor study is insufficient in China. In order to strengthen the research of C factor, this paper reviewed the developing progress of C factor, and compared the methods of estimating C value in different USLE versions. The relative studies in China were also summarized from the aspects of vegetation canopy coverage, soil surface cover, and root density. Three problems in C factor study were pointed out. The authors suggested that cropland C factor research should be furthered, and its methodology should be unified in China to represent reliable C values for soil loss prediction and conservation planning.

Wind erosion is becoming a constraining factor to agriculture and animal husbandry in the arid and semiarid area of Luanhe River. In this paper, wind erosion process was studied through simulation experiments. The results showed that soil humidity and vegetation coverage were the main factors affecting wind erosion. The wind erosion rate was decreased with increasing soil humidity and vegetation coverage, and hence, wind erosion process was reduced by modulating soil humidity and vegetation coverage in human activities.