Breakthrough curves of Cl-are measured in different bulk densities for Red soil in Hunan province and Loutu soil in Shanxi province.Average pore velocity and hydrodynamic dispersion coefficient are derived by advection-dispersion solute transport model and CXTFIT soft fitting experiment data.The results showed that a turning point of breakthrough and average breakthrough point become larger,average pore velocity decreases and hydrodynamic dispersion coefficient increases by power function respectively with increase of bulk density.Influence of bulk density on solute transport is greater in Red soil than in Loutu soil.
Although the effects of biophysical factors on runoff and sediment yields have been studied extensively, the influences of anthropogenic factors, such as economic development and population growth, which might be crucial causes of soil erosion, are still unclear. To decouple the influences of biophysical and socioeconomic variables on runoff and sediment yields, observational data on runoff and sediment from 1985 to 2015 in seven hydrological stations in Gongshui Watershed, Jiangxi Province, China, and meteorological and socioeconomic statistics during the same period were collected. A structural equation model was constructed to evaluate the effects of biophysical factors and socioeconomic factors on runoff and sediment yields. The results showed that soil erosion in the Gongshui Watershed was significantly mitigated in the past 30 years and remarkable change points occurred. Both biophysical and anthropogenic factors had significant effects on soil erosion in the watershed, and the path coefficient changed dramatically with socioeconomic development. Economic development was the most important controlling factor, and the path coefficient decreased from −0.3863 in stage I (before the change point) to −0.6174 in stage II (after the change point). The promoting effect of agricultural production mainly stemmed from its expansion brought about by agricultural output, with the total effect increasing from 0.489 in stage I to 1.017 in stage II. The contradiction between socioeconomic development and soil erosion control in the Gongshui watershed was alleviated, and the gradually formatted synergy could provide continuous support for soil erosion control.
We observed the leaf epidermal micro-morphology of 17 taxa of Iris through the scanning electron microscope,described systematically the micro-morphological features of leaf epidermis,and made comparative analysis in the classification.The results indicate that,among different taxa,the morphology of epidermal cells in leaf epidermis,stomata and epidermal papillae are of certain taxonomic significance.In Iris genus,most epidermal cells are diamond-shaped,of which some short-diamond-shaped epidermal cells are of the original type.Stomatal apparatus is of irregular type.Stomata and anticlinal walls have concave or convex types.The pattern of anticlinal walls is straight or arched.The surface gaps around concave stomata are oval,square or diamond-shaped.Some taxa have papillas on epidermis,and are of polymorphism.These traits have no direct relations with the habitat of Iris taxa.The research also explored the taxonomic relations among subgenera and some allied taxa in terms of the micromorphological features of leaf epidermis.
The sunlight intensity distribution in three training systems of Mili pear was studied.The results indicated that the sunlight intensity was all degressive from the exterior to the interior in three training systems of spindle-shaped system,open-center system and modified scatter system.The average of sunlight intensity in spindle-shaped system is higher than open-center system and modified scatter system clearly,leading to the obviously difference in yield of unit area and fruit quality.The yield mainly centralized in exterior or hypo-exterior of the crown in open-center system and modified scatter system and obviously higher than interior or hypo-interior,while the yield of all sites in spindle-shaped system was balanced relatively.The rate of high fruit quality in spindle-shaped system,open-center system and modified scatter system is 72.4%,65.7% and 62.6%,respectively.
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