Showing papers by "Chinese Academy of Sciences published in 1975"

[Soil and water loss from cultivated slope land derived from granite under different cropping systems in Three-Gorges reservoir areas].

Abstract: The water and soil loss caused by cultivation on slope land derived from granite under different cropping systems in the Three-Gorges reservoir area was analyzed based on the data from localized observation The results showed that in this area, proximately 60% of total annual rainfall, distributed in May to August, and 60% of soil erosion occurred in these four months, with 50% in June and July The coverage rates under different cropping systems differed significantly, eg, triple-cropping systems and inter-croping system with perennial plants (grass and day lily) had a bigger covering than double-cropping systems The soil loss under cropping system with peanut was much lower than that with sweet potato, because the covering rate of the former was higher than that of the latter in summer raining season The sequence of soil and nutrient loss for different cropping systems was rape (wheat) sweet potato > rape(wheat)/corn/sweet potato > rape(wheat)/corn/peanut/rape(wheat)/grass/peanut/rape(wheat)/day lily/peanut It was concluded that soil loss from cultivated slope land could be controlled below a permissible value, if rational cropping and management systems were adopted

[Analysis of environmental gradient and community of forest-swamp ecotone in Changbai mountains].

Abstract: This paper discussed the change pattern between environmental gradients and community structure, productivity and plant diversity of forest-swamp ecotones, and the mechanism forming those community's traits, which could supply a theoretical basis for conserving and managing the biological resources of ecotonal communities. By setting up sample belts along the environmental gradients on three kinds of ecotones between forests and swamps in Changbai Mountains and through investigating initial data and establishing regression models, the authors studied the dynamic pattern of species composition, diameter class and age class of dominant species, plant diversity, community productivity of forest-swamp ecotone communities with environmental gradients. The results showed that the distribution patterns of community structure characteristics, plant diversity and community productivity were consistent with the changes of environmental gradients of forest-swamp ecotones. Along the environmental gradient from swamp to forest, the displace of dominant species happened, and the species number increased by positive exponent. The diameter distribution of trees decreased by inverse curve, and the age class of trees was suited to cubic distribution. The plant diversity increased by quadratic, and the community biomass increased by cubic power curve along the environmental gradients. The above-mentioned results suggested that the relationships between communities and environmental gradients were closely related.

Effects of soil water condition and microclimate on transpiration rate of rice

Abstract: The transpiration rate and water use efficiency (WUE) of rice were studied under high, moderate and low soil water conditions (treatments A, B and C) in the red soil area of southern China. Diurnal variation of transpiration showed that rice transpiration rate was influenced by several microclimatic factors in the field. Correlation analysis and stepping multi-regression analysis suggested that the difference of relative humidity between leaf and air, and the leaf temperature were the two main factors affecting the transpiration rate of rice. The results also showed that WUE was and yield were increased significantly in treatment B. While in treatment C, the WUE increased, but the yield of late rice decreased. The transpiration rate of early rice was decreased under moderate and low soil water treatments, but this did not happen to late rice.

Soil P availability in larch rhizosphere

Abstract: Soil samples were collected from the rhizosphere and non-rhizosphere of larch(Larix gmelini) stand by exfoliation method, and the variation of P concentration was analyzed. The results show that there was no significant difference between total P concentrations in the rhizosphere and the non-rhizosphere soil, while the concentration of available P in rizhosphere soil was significantly higher than that in the non-rhizosphere soil. The concentrations of available P in rhizosphere 12 years old and 40 years old larch rhizosphered by 12.6% and 23.4% respectively, indicating that larch roots had the effect of mobilizing soil phosphorus. The components of inorganic P in rhizospheric soil were different from those in non-rhizospheric soil. The concentration of O-P was lower, and the concentrations of Al-P, Fe-P, Ca-P, NH4Cl-P were higher in the rhizosphere. The pH of rhizospheric soil was lower than that of non-rhizospheric soil, but no further acidification was observed. There was no close relationship between pH variation and available P concentration in larch rhizosphere.

Soil biota and its role in soil ecology

Abstract: Soil organisms alter soil physical, chemical and biological properties in different ways. The composition and structure of biotic communities at one hierarchical level can influence the spatial heterogeneity of resource at other hierarchical levels, and the latter is supported by a number of biologically relevant spheres-functional domains in soil. In this paper, the role of soil biota in soil ecosystem processes was assessed, and the relationship between soil biodiversity and ecosystem function was presented. Soil ecosystem responses to global change were also discussed.