266 Geyer: Ponderosa Pine Seed Sources for Windbreaks in the Central Great Plains of the U.S. Superior height growth potential can be accurately iden- tified at an early age [i.e., 5 to 15 years (Lambeth 1980; Read 1983; Van Haverbeke 1986; Schaefer and Baer 1992)]. In this analysis, data were also analyzed separately for each plantation. Analysis consisted of using the Mixed Model procedure of SAS (SAS Institute 2003) for height, trunk diameter, and D2 H (a measure of trunk volume) Family × provenance was tested as a random factor. LSMEANS/Tukey multiple range test for mean separation and χ2 terminal buds. In addition, correlations were determined among height, diameter, D2 for survival, stem crook, sweep, and number of H, and latitude and longitude of each ma- jor geographic location. The 10 major geographic provenances were compared. Most of the sources were from north cen- tral Nebraska and southern South Dakota (Figure 1; Table 1). RESULTS AND DISCUSSION Ten-year survival and growth were best from those materi- als from eastern Nebraska as reported from a greater study (Read 1983); ponderosa pine from Nebraska and South Dakota are at the extreme eastern edge of the tree’s natural range. No winter dieback or diseases were detected. The top five sourc- es for all variables were from eastern Nebraska. They came from the lower elevations (Table 1) between 710 to 800 m. Survival After 15 growing seasons, survival was good for all sources (Table 2). The mean survival of all provenances was 81.9%. Provenance survival ranged from 75.7% to 88.3%, while Kansas was 86.4% and South Dakota was 70.7%. The greater survival was from Kansas as expected as the climate is milder. The top provenances, listed in order of decreasing survival, are as fol- lows: 721NE, 996NE, 995NE, 994NE, 990NE, 720NE. χ2 tests indicated all provenances were significantly different at the 5% level. A similar test at age 10 showed 720 and 721 with 72% and 82% survival in the northern Great Plains in North Dakota. Diameter The mean diameter was 14.5 cm, ranging from 13.2 to 16 cm. All provenances were significantly different at the <1% level, using the mean contrast test. The top five were the same as listed for survival, except 995NE dropped to the bottom the list and 720 rose to the fourth position, not significantly different than any of top six (Table 2). Type 3 tests of effects are shown in Table 3 for diameter, height, and D2 H. States were significant for diameter and D2 H, but not height. Provenances were all significant at the <0.0001% level, state × provenance interactions were significant, and the family interaction with provenance were also highly significant. Height Figure 1. Collection zones (provenances) of ponderosa pine seed sources. The tallest provenances were in the eastern half of the collec- tion area (Table 2). All provenances were significantly different at the <1% level. The tallest trees listed in order of decreasing mean height are as follows: 721NE, 720NE, 990NE, 994NE, and 996NE. The mean height was 5 m, ranging from 4.7 to 5.8 m. A proceeding test to the current study (Kopp 1987), using a much larger number of provenances, found 720NE, 721NE, 855NE, and 856NE among the tallest seedlings at four years. A prove- nance test in North Dakota in 1968 and 1969 (Van Deusen 1980), Table 1. Collection zones (provenances) of ponderosa pine seed sources. Geographic Tree - provenance (#) 720 721 757 990 991 992 993 994 995 996 Total families ( #) 3 4 30 7 5 3 4 5 5 5 71 ©2011 International Society of Arboriculture Local area (town/state) Ainsworth, NE Valentine, NE Rosebud, SD Springview, NE Kilgore, NE Drinkwalter, NE Nenzel, NE Bassett, NE Snake River, NE Sparks, NE - Elevation (m) 780 800 850 740 800 859 950 710 866 800 - Latitude (°N) 42.59 42.88 43.25 42.82 42.94 42.47 42.93 42.60 42.71 42.94 - Longitude (°W) 100.00 100.55 100.82 99.75 100.97 101.07 101.11 99.54 100.97 100.24 -
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