ISSN:
0931-1890
Keywords:
Key words LAI
;
PAR
;
Light extinction
;
Pine
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract We examined empirical and simulated estimates of canopy light attenuation at SETRES (Southeast Tree Research and Education Site), a 2×2 factorial study of water and nutrients. Fertilized plots had significantly lower under-canopy PAR transmittance (TC) when compared to non-fertilized plots. Light interception efficiency, as measured by the canopy cosine-corrected light extinction coefficient, G, was significantly lower in irrigated plots for all dates examined. Estimates of G ranged from a low of 0.36 in irrigated plots in September to a high of 0.64 in March for control plots. Study-wide analyses indicate that a G of 0.50 and a k (uncorrected light extinction coefficient) of 0.69 may be reasonable parameter estimates of canopy light extinction in intermediate-aged loblolly pine plantations across a range of stand conditions and seasons when site-specific data are unavailable. Simulated TC from our version of the BIOMASS model corresponded well to the empirical estimates. Varying the vertical distribution of foliage in simulations (from 10:60:30 to 40:40:10% in the upper, middle, and lower canopy positions, respectively) resulted in only a ±7% change in total PAR intercepted, whereas varying G from 0.3 to 0.7 resulted in a 67% and 31% increase in light intercepted for control and fertilized plots, respectively. Decreased G resulted in an increased proportion of beam radiation intercepted – 63–67% of total PAR intercepted – by the middle canopy where 55–60% of the foliage was found. We hypothesize that proportionally increased productivity observed in irrigated treatments may be attributed to increased beam radiation intercepted deeper into the canopy by a greater foliage area.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s004680050190
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