Light Attenuation Model Research Articles

Light-induced alteration of the photophysical properties of dissolved organic matter in seawater: Part II. Estimates of the environmental rates of the natural water fluorescence Part II. Estimates of the environmental rates of the natural water fluorescence

From the absorbance and the product of the ‘true’ quantum yield and the absorption cross-section at specific wavelength and the solar fluxes, light attenuation model calculations were made to determine the rate of the fluorescence decay in the ocean. A mixed-layer model calculation was also used to explain the spatial and temporal variations in the fluorescence profile of natural water.

Estimating salal leaf area index and leaf biomass from diffuse light attenuation

Salal (Gaultheriashallon Pursh) leaf area index and leaf biomass were estimated from 37 quadrat samples in 13 stands dominated by Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) on eastern Vancouver Island, British Columbia. Leaf area index and biomass were predicted from a Beer's Law light attenuation model using diffuse photosynthetically active radiation (400–700 nm wavelength). The extinction coefficients, determined using reduced major axis maximum likelihood, were 0.8055 m2/m2 for leaf area index and 0.0069 g/m2 for leaf biomass. Salal leaf area index and biomass were then predicted for any convenient height in the understory canopy using a cumulative Weibull model based on dominant salal height per quadrat. The models are of use for objectively assessing the amount of Columbian black-tailed deer (Odocoileushemionuscolumbianus Richardson) winter browse and to quantify competitive leaf area.