1. Genotype by silviculture interactions on growth, stand uniformity and leaf-level gas exchange of loblolly pine varieties Marco Yanez, Thomas Fox, John Seiler

2. Nutrient Availability, Fertilizer Uptake and Efficiency Decision Support Tools and Models Remote Sensing and Leaf Area Index Weed Control and Fertilization Fertilization Response Eucalyptus Silviculture Genetics X Silviculture Interactions Response Modeling, Growth and Yield Models Ecophysiology, Process Models, Potential Productivity Initial Spacing and Thinning Water and Environmental Impacts Forest Productivity Cooperative Research Priorities:

3. Rationale Forest productivity Extensive Intensity Precision Half-sib families Full-sib familiesVarieties Silvicultural practices Tree improvement

4. Rationale Forest productivity Extensive Intensity Precision Half-sib families Full-sib familiesVarieties Silvicultural practices Tree improvement

5. Rationale Forest productivity Extensive Intensity Precision Half-sib families Full-sib familiesVarieties Silvicultural practices Tree improvement

6. Part 1: Rationale – Stand uniformity Variation in Clonal Performance Due to Silviculture Low IntensityHigh Intensity Photos by Tom Fox

7. Operational, Piedmont VA Intensive, Piedmont VA Part 1: Rationale – Stand uniformity

8. Skid trail Bedding quality Part 1: Rationale – Stand uniformity

9. Study sites The site at Virginia Piedmont North Carolina Coastal Plain

10. Experimental design Stand productivity StockingSilvicultural practices Genetic entries = + + 4 Varieties4 Varieties 1 OP family1 OP family 1 CMP family1 CMP family VA Reynolds NC Bladen 250 tpa 500 tpa 750 tpa Sites + OperationalIntensive Whole plot Split plot Split-split plot

11. Methods Virginia Piedmont Narrow-Crown Clone C1 and C3 Broad-Crown Clone C2 and C4

12. To assess the effect of silviculture on stand uniformity on loblolly pine varieties, and To assess the stability of those responses between different sites Part 1. Stand uniformity Objective

13. Growth Site x Silvi. Site x Gen

14. Part 1: Uniformity – DBH – Age 4 No effect of silviculture (p=0.054) Site by genotype interaction (p<0.01)

15. Part 1: Uniformity – Height – Age 4 No effect of silviculture (p=0.51) Site by genotype interaction (p<0.01)

16. Part 1: Stand uniformity vs stand volume

17. Part 2: Rationale- leaf physiology Variation in Leaf Level Physiology Among Varieties and Due to Silviculture Low IntensityHigh Intensity Photos by Tom Fox CO 2 carbohydrates H2OH2OH2OH2O CO 2 carbohydrates H2OH2OH2OH2O

18. To assess the effect of silviculture on leaf-level physiology on loblolly pine varieties, and To assess the stability of those responses between different sites Part 2. Leaf-level physiology Objective

19. Part 2: Measurements Tree height 3 trees/plot Total 108 trees/site Sample tree 1 Sample tree 2 Sample tree 3

20. Part 2: Measurements 2011 (3 rd growing season) 2012 (4th growing season) Photosynthesis Carbon isotope discrimination

21. 3 fascicles Part 2: Measurements

22. 1600 micromol/m2/s Asat Part 2: Measurements

23. Results photosynthesis

24. Part 2: Photosynthesis Narrow Crown Broad Crown Families

25. Part 2: Carbon isotope discrimination NCVA Narrow Crown Broad Crown Families

26. Correlation between physiological parameters and accumulated volume at age 4

27. Narrow-Crown Clone C1 and C3 Broad-Crown Clone C2 and C4 Leaf physiology Leaf area Canopy conductance N demand Intraspecific competition Stand dynamic Etc. Part 3: Rationale – Within crown variation

28. Low Silviculture High Silviculture Is nitrogen deficiency expressed first in the lower crown? Asat N Part 3: Rationale – Within crown variation

29. Narrow-Crown Clone C1 and C3 Broad-Crown Clone C2 and C4 Asat N Part 3: Rationale – Within crown variation

30. To assess the intra-crown variability on leaf- level physiology on loblolly pine varieties, and Part 3. Leaf-level physiology ‘within crown variation’ Objective

31. Part 3: Within crown variation in Asat Upper Crown Lower Crown Tree height Sampled tree Asat N (%)

32. Nitrogen: Site by crown position interaction

33. Silv by crown position Interaction on Asat and N

34. Gen by crown position Interaction on Asat and N

35. Conclusions Genetic by silvicultural effects on growth (magnitude of the response was site specific). Stand uniformity is not a trait intrinsic to varietal stand, but higher uniformity increased stand productivity. Some genotypes differed in both growth and gas-exchange parameters. Gas exchange parameters did not explain the differences in growth.

36. Implications Differences in canopy architecture affect the rate of canopy closure. Differences in physiology among the genotypes may interact with stand development to affect forest productivity Total canopy PS Impact of competition on crown development after crown closure

37. Differences in leaf area will affect total stand PS and carbon capture even if leaf level PS is the same Narrow-Crown Clone C1 and C3 Broad-Crown Clone C2 and C4 Age 3

38. Methods: Photosynthesis, part 1

39. Differences in leaf area will affect total stand PS and carbon capture even if leaf level PS is the same Age 5

40. modelling Modelling efforts to predict future performance

41. Questions Marco Yanez and John Peterson setting up equipment Photosynthesis being measured at Bladen lakes, NC