[Phenological characteristics of introduced Polygonum viviparum from high altitude to low altitude area].

OBJECTIVE: To explore the phenological characteristics of Polygonum viviparum introduced from high altitude to low altitude area. METHODS: To introduce the root and seed of Polygonum viviparum from high altitude to low altitude area and collect their growth and phenological data. RESULTS: In low altitude area, Polygonum viviparum germinated at the beginning of March, grew from March to the end of July, withered during the whole August due to high temperature, recovered from the end of August to the beginning of October, and then withered again due to low temperature. Its reproduction lasted from April to the end of July, stagnated from the beginning of August to the middle of September, and recovered from the middle of September to the end of October. CONCLUSION: The high temperature of August in low altitude area is the bottleneck season for Polygonum viviparum, yet it can grow normally while such technologies are applied to its culture as early seeding, culture seedling with fertilizing soil ball, complete overshadow etc.

[Spatial-temporal evolution of ecological land and influence factors in Wuhan urban agglome-ration based on geographically weighted regression model]. / åŸºäºŽåœ°ç†åŠ æƒå›žå½’æ¨¡åž‹çš„æ­¦æ±‰åŸŽå¸‚åœˆç”Ÿæ€ç”¨åœ°æ—¶ç©ºæ¼”å˜åŠå½±å“å› ç´ .

Ecological land is essential to sustainable development of urban agglomeration. Based on the results of remote sensing image interpretation, we analyzed the spatial-temporal evolution of ecological land in 32 research units of ecological land in Wuhan urban agglomeration in 2000-2005, 2005-2010 and 2010-2015, using the land use transition matrix, exploratory regression analysis, the ordinary least squares (OLS) model, and geographically weighted regression (GWR) model. Then, the best regression model was selected after perfecting the traditional index system of influencing factors by data of the location and quantitative information of companies, enterprises and life services, etc., and conducting exploratory regression analysis. Finally, we analyzed the influencing factors and spatial differentiation rules of different research periods with GWR model. The results showed that, from 2000 to 2015, the amount of transition from ecological land use to non-ecological land use in the urban agglomeration showed an inverted U-shaped change pattern, and the space showing the expanding trend from point to surface. Land use patterns of 8.4% area had changed in the urban agglomeration, among which the conversion of cultivated land, forest land, grassland, water body and unused land to non-ecological land accounted for 41.9% of the total area. The spatial pattern gradually expanded from the central urban area of Wuhan to the periphery of the municipal sub-center and county-level towns. The total number of passing models in the three stages of exploratory regression analysis was 326. The GWR and OLS regression were used for comparative analysis of all models. The adjusted R2 in the three stages of selected models were 0.83, 0.91 and 0.76, respectively. The former improved by 0.02, 0.03 and 0.02, and the AICc decreased by 2.88, 3.42 and 0.83, respectively. The results of GWR model showed substantially spatial differentiation of influencing factors of ecological land evolution in Wuhan urban agglomeration, and that the influence patterns was dominated by gradual transition in different directions in space, with other patterns such as "V" distribution. The effects of spatial factors were significant. The potential information of spatial data enhanced the interpretation of ecological land evolution within the urban agglomeration.

[Review of CO2 and CH4 Emissions from Rivers].

Streams and rivers play a major biogeochemical role in the global carbon cycle and act as hot spots for carbon dioxide (CO2) and methane (CH4) emissions to the atmosphere, excepting their roles of transporting the water and carbon from the terrestrial environment to the ocean. While carbon gases have been of great global concern, systematic reviews are still scarce. Given recent recognition of the pervasiveness of CO2 and CH4 in streams and rivers, this study synthesized existing research and discoveries to identify patterns and controls for riverine CO2 and CH4, knowledge gaps, and research opportunities. This study presented a conceptual framework for sources and the fates of CO2/CH4 from streams and rivers and used this framework to understand the dynamic processes of fluvial carbon evasion and potential anthropogenic disturbances. Multiple environmental influences combined with different contributions of endogenous metabolism and terrigenous input, and the CO2 and CH4 in streams and rivers showed significant spatial and temporal variability on a global scale, regional scale, and watershed scale, which indicates a substantial challenge for understanding the larger-scale dynamics. For a clearer recognition of how the changing environment and human activities may modify fluvial CO2 and CH4 dynamics, this study constructed a system framework of controls on CO2 and CH4 production and persistence in streams and rivers. The framework of controls can be viewed in terms of endogenous environmental controls that influence river metabolism (organic matter, temperature, nutrients, pH, and alternative electron acceptors) and external factors, including geomorphic and hydrologic drivers and human activities (agriculture, damming, and urbanization). We point out that the carbon emissions from rivers should be integrated into the terrestrial carbon budget, and in the future, more attention should be given to research on the sources of CO2 and CH4 in rivers, the generation and diffusion of CO2 and CH4 at different interfaces, the spatiotemporal variability of riverine carbon emissions, and the response of riverine CO2 and CH4 dynamics to the changing environment and human activities.