The energy budget and regulating factors were investigated over an estuarine wetland during one year of continuous measurement in 2006.The results show that the seasonal changes of the energy fluxes and Bowen ratio(β) were greatly affected by incoming shortwave radiation and canopy growth.During the non-growing season and early-growing season, sensible heat(H) dominated the energy flux, and β could reach a maximum of 2.5, while during most of the growing season, latent heat dominated the energy flux and β fluctuated from 0.4 to 1.0.The energy budget ratio in growing season was about 0.76, and the value would be higher if heat exchange during tidal flooding was in-cluded.During tidal flooding days, β was slightly higher than that at exposure days in most cases.Vegetation cover seems exert little effect on energy partitioning except in March when the standing dead grass intercepted the incoming radiation that might reach the soil surface and reduce the turbulence between soil and atmosphere, thus suppressing the evaporation from the soil though the soil mositure was high at that time.
Aims Road effects from maintenance and traffic have the potential to alter plant communities,but the exact relationships between these effects and changes in plant community composition have not often been studied in diverse environments.To determine the direction and level of community composition changes in saline environment due to road effects,we conducted a study along roads of different ages and in nearby non-road(i.e.natural)areas in the Yellow River Delta,China.Additionally,to potentially elucidate the mechanisms underlying the changes in the richness and composition of plant communities along roads,we evaluated physiochemical changes in soil of roadside and non-road areas.Methods Floristic and environmental data were collected along roadside of different ages and nearby non-road areas.To evaluate plant communities at each site,six 2 m 32 m quadrats were placed at 3-m intervals along roads and six quadrats were arranged randomly in non-road areas.To determine the difference in plant community composition betweenroadside andnon-road areas,wemeasuredspecies richness and the abundance of each species,examined species turnover and floristic dissimilarity between the two areas and positioned plant species and sites in an abstract multivariate space.Plant community(species richness,percentage of halophytes)and soil physicochemical properties(pH,salinity,moisture content,bulk density,nitrate and ammonium nitrogen concentration)were compared between roadside and non-road areas(young roadside vs.corresponding non-road areas,old roadside vs.corresponding non-road areas)by using t-tests.Classification and ordination techniques were used to examine the relationship between vegetation and related environmental variables in both roadside and non-road areas.Important Findings For both the young and old roadside areas,species richness in roadside areas was significantly higher than in non-road areas and high floristic dissimilarity values indicated that roadside and non-road areas differed greatly in community compositio
