气候变化领域集成服务门户

Rainfall interception shelters are frequently used to study the ecological consequences of drought. One common shelter design employs V-shaped plastic troughs spaced on a supporting frame to intercept rainfall. Shading, reflection, and infrared radiation may alter the radiative environment under shelters in ways independent of their intended effect on soil moisture. We measured microclimate and several photosynthetic variables for watered, potted plants under rain-out shelters and in open-air, unsheltered plots. We tested whether the shelter infrastructure altered aboveground micrometeorology and photosynthesis for watered, potted plants of native Californian species: Elymus glaucus, Eriogonum latifolium, Mimulus aurantiacus, and Morella californica. We quantified the effects on photosynthesis in terms of light harvesting by photosystem II (PSII) and leaf-level gas exchange on open-air and shelter plots, the quantum yield of PSII for darkened leaves, dark respiration, and nocturnal stomatal conductance. The rain-out shelter reduced daily integrated photosynthetically active radiation by 20%. Air temperature, leaf temperature, and leaf-to-air vapour pressure difference were not different under shelters compared with controls during the day. Likewise, there were no effects of shelters on net CO2 assimilation, stomatal conductance to water vapour (g(s)), internal leaf (CO2), or electron transport rate through PSII during the daytime. At night, T-air was 0.6 degrees C higher under shelters, but there were no effects on dark respiration or stomatal conductance. Despite some differences in micrometeorology under rain-out shelters compared with open-air plots, there were little or no aboveground nondrought effects of the shelters on leaf-level photosynthesis for watered, potted plants of these California native plant species.