Fig. 3: Effect of temperature on simulated cell-mass density across the radial profile under different model configurations and forcings in Pinus sylvestris L. at the same site as in Fig. 2, 1995.

a Simulated cell-mass density using observed temperatures ("full model'') and with +2 K applied daily to both cell enlargement and wall thickening ("full model +2 K'')’ or only wall thickening ("wall thickening only +2 K''). Also shown is the result of applying the temperature increment to both cell growth and wall thickening but with the carbohydrate limitation to cell-wall growth removed ("sugar saturation +2 K''), as in Fig 2b. Each circle is an individual cell at the end of the year, and solid lines are mean density profiles across 100 radial files for each model configuration (running means over three 40 μm-wide bins). b Ratio of change in density to change in temperature calculated by subtracting the mean profiles of 100 radial files at +2 K from the mean profiles at observed temperatures ("full model''). The dot-dash line is the difference between a run where +2 K was applied to wall thickening only and a run using observed temperatures ("wall thickening only''). Also shown (dashed line) is the difference between a run with both non-limiting carbohydrates and +2 K applied to cell growth and wall thickening and one when carbohydrates are non-limiting but at observed temperatures ("sugar saturation'').