William L. Bauerle*, Alex B. Daniels, and David M. Barnard

Carbon and water flux responses to physiology by environment interactions: A sensitivity analysis of variation in climate on photosynthetic and stomatal parameters

Climate Dynamics

William L. Bauerle*, Alex B. Daniels, and David M. Barnard

Department of Horticulture and Landscape Architecture, Colorado State University, Fort Collins, Colorado, USA 80523-1173

*Correspondence author

Email: ; Phone: (970) 491-4088; Fax: (970) 491-7745

Supplemental Figure 1. Photosynthetically Active Radiation (PAR) (µmol m-2 s-1) of North America: One of five environmental variables used to assess differences in physiological parameter effects in response to variation across multiple environmental variables. The data represent mean values of June maximum daytime PAR values from 1984 to 2005 with a 110 km spatial resolution (NASA, 2007).

Supplemental Figure 2. Air temperature (°C) of North America: One of five environmental variables used to assess differences in physiological parameter effects in response to variation across multiple environmental variables. The data represent mean June daytime temperatures from 2001 to 2010 with a 5.5km spatial resolution (NASA, 2010).

Supplemental Figure 3. Near surface wind speed (m s-1) of North America: One of five environmental variables used to assess differences in physiological parameter effects in response to variation across multiple environmental variables. The data represent mean June wind speeds from 1979 to 2011 with a 110 km spatial resolution (NASA, 2011).

Supplemental Figure 4. Relative humidity (%) of North America: One of five environmental variables used to assess differences in physiological parameter effects in response to variation across multiple environmental variables. The data represent mean June daytime relative humidities from 1984 to 2005 with a 62.7 km spatial resolution (NASA, 2008).

Supplemental Figure 5. Air pressure (kPa) of North America: One of five environmental variables used to assess differences in physiological parameter effects in response to variation across multiple environmental variables. Air pressure was derived from a digital elevation model raster (3.3km resolution) using a form of the ideal gas law / hypsometric equation .

Results for Supplemental Figure 6

Supplemental Figure 6a and b illustrate the effect of Vcmax and α on photosynthesis output in a simulated stand of trees over 1) the red maple native range and 2) North America in general (inset). Using the genetically constrained intraspecific red maple parameter range, the effect of Vcmax on photosynthesis varies by location and ranges between ~2.5-25% over the red maple native range. The effect is more influential in northern latitudes and outside of the red maple native range, Vcmax is important in mountainous portions of the western United States of America (inset) and maintains an equivalent parameter effect over North America (inset). The effect of α is higher in general and opposite in latitude to Vcmax. Although the effect of α on photosynthesis also varies by location, it maintains a parameter effect range between ~10-27% over the native red maple range and increases in influence at lower latitudes and western portions of North America (inset). It appears to be particularly important for estimating photosynthesis within the environmental conditions of the continental United States of America.

Supplemental Figure 6. The change in the parameter effect percentage (%) of (a) the maximum carboxylation rate of Rubisco (Vcmax) and (b) the quantum yield of electron transport (α) on estimates of gross primary productivity in a simulated forest stand across the Acer rubrum L. native range (Walters and Yawney 1990) and the wide environmental gradient of North America (inset). The % represents the difference between model estimates from the high and low Jmax or Vcmax parameter range relative to a model estimate at a base case Jmax or Vcmax value for the intraspecific Acer rubrum L. range reported in Bauerle and Bowden (2011) (Jmax; 175.22 ± 64.73 µmol m-2 s-1) and (Vcmax; 69.06 ± 15.76 µmol m-2 s-1). The solid line outlines the approximate boundaries of the Acer rubrum L. native range and hashed lines designate areas outside of the native range. (Insets) Genetically constrained intraspecific parameter ranges illustrating parameter effects by environment across the North American summer time climate. We parameterized the representative deciduous forest as follows: 5 m2 m-2 leaf area index; 5 m stem spacing, 10 m canopy height, ellipsoid crowns, 2.5 m x 2.5 m crown radius, 7.5 m length of the live crown, and 0.1 m stem diameter located on a 0° slope. The average deciduous forest individual tree size attributes and spacing characteristics for hypothetical regional and continent model projections were derived from Abrams (1998) and Perry et al. (2008).