RESUMO
Through quantitatively adjust soil electric field, we investigated the effect of soil electric field on aggregate stability and soil erosion in black soil region of Northeast China with the experiments of wet sieving and rainfall simulation. Results showed that: 1) Soil surface potential absolute value and electric field strength increased with the decreases of electrolyte concentration in bulk solution. Soil electric field strength could reach to 108 V·m-1. 2) With the increase of soil electric field strength, the degree of fragmentation of soil aggregates increased and the mean weight diameter (MWD) decreased sharply first and then kept constant. 3) With decreasing electrolyte concentration and increasing surface potential, the amount of soil loss increased. As the electrolyte concentration was <0.01 mol·L-1, the corresponding soil surface potential was > 210 and 209 mV for Bin-xian and Keshan, respectively, the cumulative amounts of soil loss with rainfall time almost overlapped, suggesting that the electrolyte concentration of 0.01 mol·L-1 was the threshold for soil erosion. 4) There was a linear relationship between soil cumulative loss and MWD. Our results indicated that soil electric field strength increased as the rain enters into the soil, which could induce soil aggregate breakdown and release amounts of fine soil particles. Finally, soil erosion occurred under the driving of flowing water. Our results provided insights into the mechanism underlying soil erosion in the black soil region of Northeast China.
Assuntos
Solo , Água , China , Chuva , Movimentos da ÁguaRESUMO
Carbon (C), nitrogen (N) and phosphorus (P) stoichiometry from the aboveground parts of plants, roots, plant litter and soils, as well as their relationships were studied in grassland under four distinct types of vegetation recovery including natural grassland, grassland with shrubs, grassland after grazing exclusion, and abandoned cropland in Yunwu Mountain, China. The results showed that there was significant correlation among the ecological stoichiometric characteristics of soils with the aboveground parts and roots. The relation between the aboveground parts and roots was closer in P concentration than in N concentration. The linkage of plants and soils was closer in N concentration than in P concentration. The ecological stoichiometric relationships between soils and litter as well as between roots and litter were weak. There was no significant difference between the aboveground parts and roots in total C and N storages among four distinct recovery methods. How-ever, the P storage differed greatly among the four recovery types with the maximum of 0.49 g·m-2 in the abandoned cropland and the minimum value of 0.29 g·m-2 in the grassland after grazing exclusion. Grazing prohibition duration had minor effects on ecological stoichiometric characteristics. The 12-year-abandoned cropland had lower soil organic C and total N concentration (9.98 and 1.07 g·kg-1, respectively) compared with natural grasslands (14.27 and 1.55 g·kg-1, respectively), and this difference of ecological stoichiometric characteristics was caused by the high P concentration in abandoned cropland. The roots N and P concentrations were the lowest in natural grassland with 6.25 and 0.57 g·kg-1, respectively, due to the greatest amount of root biomass. The N and P concentrations in the grassland with shrubs were relatively lower in the aboveground parts(12.77 and 0.98 g·kg-1,respectively) while relatively higher in roots (9.30 and 0.77 g·kg-1, respectively). Overall, the plant composition was the key factor that influenced the ecological stoichiome-tric characteristics of plant communities. The distinctions of the ecological stoichiometric characteristics among different restoration types decreased with the increasing Sorensen index.
Assuntos
Pradaria , Nitrogênio , Solo , Biomassa , Carbono , China , PlantasRESUMO
Choosing the soils under different vegetation recovery of Heidaigou dump as the research objects, we mainly analyzed their basic physical and chemical properties and enzyme activities with the method of Analysis of Variance as well as their relations using Pearson correlation analysis and path analysis hoping to uncover the driving factors of the differences between soil enzyme activities under different vegetation restoration, and provide scientific suggestions for the plant selection as well as make a better evaluation to the reclamation effect. The results showed that: (1) Although the artificial vegetation restoration improved the basic physical and chemical properties of the soils while increasing their enzyme activities to a certain extent, the soil conditions still did not reach the level of the natural grassland; (2) Contents of soil organic carbon (SOC) and soil total nitrogen (TN) of the seabuckthorns were the nearest to those of the grassland, which reached 54. 22% and 70. 00% of those of the grassland. In addition, the soil bulk density of the seabuckthorns stand was 17. 09% lower than the maximum value of the amorpha fruitcosa land. The SOC and TN contents as well as the bulk density showed that seabuckthorns had advantages as the species for land reclamation of this dump; Compared with the seabuckthorn, the pure poplar forest had lower contents of SOC and TN respectively by 35.64% and 32.14% and displayed a 16.79% higher value of soil bulk density; (3) The activities of alkaline phosphotase under different types of vegetation rehabilitation had little variation. But soil urease activities was more sensitive to reflect the effects of vegetation restoration on soil properties; (4) Elevation of the SOC and TN turned out to be the main cause for soil fertility restoration and increased biological activities of the dump.