© 1995 Heron Publishing—Victoria, Canada
Evaluation of sampling schemes for estimating instantaneous whole-tree photosynthesis in Populus clones: a modeling approach
A. T. Wolf (1), T. E. Burk (1) and J. G. Isebrands (2)
1. Department of Forest Resources, University of Minnesota, St. Paul, MN 55108, USA / 2. Forestry Sciences Laboratory, USDA Forest Service, Rhinelander, WI 54501, USA / Received April 7, 1994
Summary
We evaluated several sampling schemes for estimating instantaneous whole-tree photosynthesis of 1-year-old Populus clones. Growth of two clones was simulated under varying weather conditions and leaf orientation scenarios providing photosynthetic
data on a leaf-by-leaf basis throughout the growing season. Simple random sampling, stratified random sampling and a series
of physiologically based sampling schemes were evaluated using either whole-leaf photosynthesis or photosynthetic rate (i.e.,
photosynthesis per unit leaf area) as the sampling attribute. Ratio and regression estimators with leaf area as an auxiliary
variable were also studied. On the basis of their bias and accuracy in estimating instantaneous whole-tree photosynthesis
(mg CO2), the physiologically based sampling schemes were superior for all combinations of clone type, weather condition and leaf
orientation. Aspects of extending the sampling process to estimate daily and seasonal photosynthesis are also elaborated.
Keywords:
ECOPHYS, leaf orientation, photosynthetic rate, poplar, weather.
