Thinning Impacts on Even-aged Stands of Eucalyptus in Brazil

1. Thinning Impacts on Even-aged Stands of Eucalyptus in Brazil Gilciano S. Nogueira – UFVJM/Brazil Peter L. Marshall – UBC/Canada Helio Garcia Leite – UFV/Brazil Valerie Lemay – UBC/Canada João Carlos Chagas Campos – UFV/Brazil Western Mensurationists’ Conference June 21, 2010 Missoula, MT

2. Introduction • Plantation forest in Brazil: 6.6 million hectares, representing 0.8 % of the land area • From 2004 to 2008 the area in eucalyptus plantation increased by 33.1%, or 1.1 million ha solid wood products is minimal

3. Introduction • Advances in wood technology and design have allowed various uses of eucalyptus wood as a solid product

4. Introduction • The demand for wood from large trees has been supported by illegal harvesting in native forests • Consequently, there are also few studies on the impact of thinning in stands of eucalyptus in Brazil

5. Introduction • Thinning in eucalyptus forests can help increase Brazilian participation in the global market for solid wood products and may reduce pressure on Brazilian native forests • Studies of thinning in eucalyptus are strategic for Brazil, both economically and environmentally

6. Introduction • An experiment was established to obtain a database reliable for analyzing the difference among thinning treatments and for developing growth and yield models for thinned eucalyptus stands • Requirements: • Selection of the sample units was deliberate (selective sampling), so that representation of the medium and extreme site conditions is guaranteed • The sample units were sufficiently large to faithfully represent the silvicultural practices applied to the remainder of the stand

7. Objective To analyze the effect of thinning on growth of stand variables in eucalyptus forests

8. Overview of the experiment • Species: Eucalyptus grandis x Eucalyptus urophylla hybrid • Location: Northeast region of Bahia State, Brazil

9. Overview of the experiment • - Planting date: June/July 1993 • - Date of installation of the permanent plots: September 1995 • Company: Bahia Specialty Cellulose (BSC) (http://www.bahiaspeccell.com) • Initial spacing between trees: 3.0 X 3.0 m • - Thinnings accomplished: two selective thinnings, in 1998 and 2004 • - Final harvest: at the end of 2007

10. Experimental Design - based on level-of-growing-stock installation standards - Located in 3 installations, comprising medium and good quality site conditions

11. Experimental Design • Replicated randomized complete block with repeated measures • 6 blocks (two in each installation), each one involving two repetitions; • 4 treatments, corresponding to different basal area percentages removed in each thinning : Treatment 1: 20% without pruning; • Treatment 2: 35% without pruning; • Treatment 3: 50% without pruning; • Treatment 4: 35% with pruning up to 6.0 meters; • Each block contained 8 permanent rectangular plots, with an area of 2,600 m2, totaling 48 plots (6 blocks x 2 repetitions x 4 treatments)

12. Experimental Design • - Layout C Block 1 Block 2 A Block 1 B Block 1 Block 2 Block 2

13. Experimental Design • Replicated randomized complete block with repeated measures • 6 blocks (two in each installation), each one involving two repetitions; • 4 treatments, corresponding to different basal area percentages removed in each thinning : Treatment 1: 20% without pruning; • Treatment 2: 35% without pruning; • Treatment 3: 50% without pruning; • Treatment 4: 35% with pruning up to 6.0 meters; • Each block contained 8 permanent rectangular plots, with an area of 2,600 m2, totaling 48 plots (6 blocks x 2 repetitions x 4 treatments) • Plots were buffered by a few rows of trees on each side

14. Marked boundaries of a plot

15. Measurements - Data

16. Measurements After 1st thinning (61 months) After 1st thinning (101 months) After 2nd thinning (165 months) After 1st thinning (87 months)

17. Volume equation outside bark: inside bark:

18. Volume equation outside bark inside bark

19. Height equation Installation A Installation B Installation C

20. Height equation A B

21. Height equation C

22. Growth trend Mean per treatment Individual values

23. Growth trends Mean per treatment Individual values

24. Growth trends Mean per treatment Individual values

25. Growth trends Mean per treatment Individual values

26. Analysis Variables: - periodic monthly increment (absolute): total height, dominant height, quadratic mean diameter and volume per tree - periodic monthly increment (percentage): basal area per hectare and volume per hectare A and B Periods: C 1 (61 to 87) 2 (87 to 137) 3 (147 to 165) 1 (61 to 87) 2 (61 to 87)

27. Analysis Anova: Mixed linear model, with thinning as the whole plot factor and period as the split-plot factor Fixed effect: thinning Random effect: block block*thinning Repetition(block*thinning) period period*thinning Pairwise comparisons: Bonferroni test

28. Effect on periodic increment of average total height There is thinning effect A B C A: only thinning 35% and thinning 35% + pruning were equal B and C : Only thinning 20% was different from the other treatments

29. Effect on periodic increment of dominant height No thinning effect

30. Effect on periodic increment of quadratic mean diameter There is thinning effect A B C A, B and C: only thinning 35% and thinning 35% + pruning were equal

31. Effect on periodic increment of basal area per hectare There is thinning effect A B C A, B and C: only thinning 35% and thinning 35% + pruning were equal

32. Effect on periodic increment of volume per hectare There is thinning effect A B C A, B and C: only thinning 35% and thinning 35% + pruning were equal

33. Effect on periodic increment of volume per tree There is thinning effect A B C A, B and C: only thinning 35% and thinning 35% + pruning were equal

34. Conclusion No surprise!

35. Conclusion • Thinning affected the growth of total height, diameter, basal area per hectare, total volume per tree and total volume per hectare, but did not affect the growth of dominant height • Thinning prevented regular tree mortality • Prunning did not affect the growth trend of the variables analyzed

36. nogueirags@gmail.com