1. DAYCENT Simulation of two Contrasted Atmospheric N Deposition Forests Fengming YUAN 22 June 2007

2. DAYCENT Model - issues with previous results

3. DAYCENT Model - issues with previous results

4. DAYCENT Parameterization - Sensitive Parameters fix.100   Others: DEC(1), PMCO2(1), P1CO2a(1)   damr(1,1) ---- fraction of surface N absorbed by residue Range: 0.0 to 1.0

5.   Two sites: High-N site – Camp Paivika: 7.15 gN/m2/yr (since 1942 ) Low-N site – Barton Flats/Camp Oscela: 0.88 gN/m2/yr (since 1942 )   N deposition rates (gN/m2/yr) : 0.1, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, and 7.0   Tree ages: from 1900 from 1942 Model Runs I. I.Mixed conifer forests

6. Results I. I.Current N deposition   Questions:  How does ecosystem response in terms of productivity and N cycling?  Would ecosystem reach a new steady state? And if yes, When?  What indicators would be good for so- called forest N saturation, using modeling approach?

7. Results I. I.Current N deposition   Ecosystem C and N concentration CP1-0.1/BF1-0.1: background N deposition, CP1-71.5/BF1-8.8: current level N deposition assuming forests regenerated in 1900, and, CP2-71.5/BF2-8.8: current N deposition but assuming forests growth in the beginning of depositions.

8.   Ecosystem N Accumulation and losses Results I. I.Current N deposition CP1-0.1/BF1-0.1: background N deposition, CP1-71.5/BF1-8.8: current level N deposition assuming forests regenerated in 1900, and, CP2-71.5/BF2-8.8: current N deposition but assuming forests growth in the beginning of depositions.

9.   Objectives: Results II. II.N deposition rates  Critical Loads  Threshold

10.   Objectives: Critical loads/Thresholds Results II. II.N deposition rates Highly variable from year to year Highly variable from year to year What indicators? What indicators?

11.   N deposition rate effects on productivity Results II. II.N deposition rates Mean +/- StDev. Over 1942 ~ 2005 Mean +/- StDev. Over 1942 ~ 2005

12.   N deposition rate effects on N accumulations Mean +/- StDev. Over 1942 ~ 2005 Mean +/- StDev. Over 1942 ~ 2005 Results II. II.N deposition rates

13.   N deposition rate effects on N mineralization and losses Results II. II.N deposition rates

14.   N deposition rate effects on N losses Results II. II.N deposition rates

15. DAYCENT consideration for Landscape Levels

16.   Soils Other factors III. III.Soils, N deposition variability, fire regime, …….

17.   Soils Other Factors III. III.Soils, N deposition variability, fire regime, …….

18. Yes ? Initial conditions Initial conditions   Can DAYCENT be running at landscape level ? Other Factors III. III.Soils, N deposition variability, fire regime, ……. Output “relay” Output “relay” Input/parameter file “generator” Input/parameter file “generator”

19. Next …   DAYCENT parameterization for CSS  Model parameters for shrub/native grass ? Shrub vs. invasive grasses

20. Next …   DAYCENT parameterization for CSS ? Shrubs vs. invasive grasses in term of N utilization (Padgett & Allen, 1999. Plant Ecology, 144: 191-193)

21. Next …   DAYCENT parameterization for CSS ? Shrubs vs. invasive grasses in term of N utilization (Padgett & Allen, 1999. Plant Ecology, 144: 191-193) N Uptake Capacity Vs. N concentration