WIDESPAC.DOC

Explanation of Widespac.dat - measurements for 3 inventories (at ages 2, 3, and 4)

This file contains measurement for three inventories of seedlings from the Wide Spacing comparative study. This study is designed to look at the effects of agroforestry practices without growing nurse trees (shortleaf pine) along with the crop trees (loblolly pine). There were a total of four seedlings planted at each seedling location (similar to the four seedlings planted at the center of each cluster). A total of 108 seedlings were planted at each site (a total of 324 seedlings were initially planted). The loblolly pine seedlings that were originally planted in 1998 were obtained from the International Paper Co. nursery in Bluff City, AR. The shortleaf pine seedlings that were originally planted in 1998 came from a nursery in Missouri that is operated by the Missouri Forest Commission. Seedlings replanted in 1999 came from the Arkansas Forest Commission=s Baucum nursery located in Little Rock.

Units: English

Lines: 810

Variables: 19

Columns:

1. Site - one of the three sites that contain comparative studies.

2. Age - age of trees from seed. Genetically superior 1-0 seedlings were planted. One complication is that during the first two years of this study seedlings were replanted where other seedlings had died. Therefore cluster-level variables for age 3 may actually have some age 2 trees within their measurements, etc.

3. Seedling location or cluster (SL) - a location where four seedlings were initially planted similar to the clusters to the agroforestry study with shortleaf nurse trees (a total of 27 locations within site). Two were thinned in March of 2000. By December of 2000 only one seedling should remain at each location.

4. Tree number (TN) - within a seedling location. Individual seedling growth cannot be tracked from one year to the next. This is because during the inventory, trees did not have a set measurement protocol.

5. TPA - trees per acre.

6. TPAdbh - number of trees per acre that have a Dbh.

7. GLD - ground-line diameter (in inches).

8. DBH - diameter at breast height (in inches).

9. TTH - total tree height (in feet).

10. Arithgld - The arithmetic mean ground-line diameter (in inches).

11. Stdgld - Standard deviation of arithmetic ground-line diameter.

12. Arithd - The arithmetic mean diameter at breast height (in inches).

13. Stddbh - Standard deviation of arithmetic mean diameter

14. QMD - Quadratic mean diameter at breast height (in inches).

15. Aritht - The arithmetic mean total tree height (in feet).

16. Survival - Percent survival for all seedlings planted within a site (initial TPA was 360). Survival was not calculated for age 4 because a selective thinning occurred in March of 2000. Replanting was conducted in 1999 if a cluster had less than two surviving seedlings. For these clusters, seedlings were replanted so that the cluster would have four seedlings. They were thinned to two seedlings per cluster in March of 2000, and thinned to one seedling per cluster in December of 2000.

17. Seedling location survival (SLS) - Percent survival by seedling location. This value determines the number of seedling locations that had at least one seedling surviving (a total of 27 seedling locations per site). This value was calculated for age 4.

18. SDI - stand density index (calculated using TPAdbh rather than TPA).

19. BAA - Basal area per acre (calculated average basal area of trees with a DBH, and then multiplied this by TPAdbh).

Example:

3 4 22 1 170 157 1.4 0.2 5.5 1.62 0.40 0.58 0.21 0.61 6.34 . 1.00 1.45 0.32

The following code can be used to input widespac.dat into SAS:

data widespac ; infile 'c:/widespac.dat' ; input site age row tn tpa tpadbh gld dbh tth arithgld stdgld arithd stddbh qmd aritht survival rowsurv sdi baa ; run ;