Surface energy fluxes of Phragmites australis in a prairie wetland

摘要: Abstract Components of the surface energy balance were measured in three communities (Phragmites australis, Scirpus acutus, and open water) a wetland located northcentral Nebraska, USA, during growing season 1994. This paper includes results from area covered by Phragmites australis (reedgrass). The Bowen ratio – method was used to calculate sensible latent heat fluxes. During daytime, with water depth about 0.5 m, storage term (G) consumed 20–30% net radiation (Rn). At night, G significant source (on average, 40 W m−2). magnitude daily (24 h) averaged small. Evapotranspiration (ET) major consumer incoming solar energy. early peak growth, ET ranged between 2.5 6.5 mm per day. senescence, evapotranspiration 0.5 3.1 mm partitioned into transpiration (Ev) evaporation (Es) using dual-source modification Penman–Monteith equation. Results indicated that contributed 40–45% total beginning growth stage. second half stage entire stage, it 53–62% ET. contribution decreased 50% near zero late senescence. daytime variation Es did not follow Rn, seemed be controlled thermal stability air dryness. Before actual equilibrium (ET/ETeq) 1.3. It McNaughton Spriggs (1989, IAHS Publ. 177, 86–101) model, developed primarily for dryland vegetation, significantly overestimated ET/ETeq when canopy stomatal resistance larger than 150 s m−1. model prediction improved eliminated substituting Ev/Eveq (transpiration/equilibrium transpiration).