scholarly journals Modeling Early Responses of Loblolly Pine Growth to Thinning in the Western Gulf Coastal Plain Region

2020 ◽  
Vol 66 (5) ◽  
pp. 623-633
Author(s):  
Y H Weng ◽  
J Grogan ◽  
D W Coble

Abstract Growth response to thinning has long been a research topic of interest in forest science. This study presents the first 3–4 years of response of loblolly pine (Pinus taeda L.) growth to thinning at different intensities. Data were collected from the East Texas Pine Research Project’s region-wide loblolly pine thinning study, which covers a wide variety of stand conditions. Four treatments, light, moderate, and heavy thinning, respectively having 370, 555, and 740 residual trees per hectare after thinning, and an unthinned control, were included. Individual tree diameter at breast height (dbh) and total height were recorded annually for the first 3–4 years after thinning. Results indicate significant differences between treatments in dbh growth in each year after thinning, as well as for all years combined. Each thinning treatment had significantly greater dbh growth than the control in the first growing season with this positive response being more evident in the case of the heavier thinning or at the later years post-thinning. Conversely, the thinning effect on tree height growth was initially negligibly negative, then becoming positive after 2–4 years, with the heavier thinning becoming positive sooner. Tree size class, assigned based on prethinning dbh, had a significant effect on both dbh and height growth responses. Compared to the control, small trees had a greater response both in dbh and in height growth than the medium and large trees over the measurement period. At the stand level, the heavier thinning had significantly less stand basal area per hectare, but the difference in stand basal area per hectare between the thinned and the unthinned plots decreased with years post-thinning. Results from this study can improve our understanding in thinning effects and help forest managers make accurate decisions on silvicultural regimes.

1998 ◽  
Vol 28 (9) ◽  
pp. 1344-1351 ◽  
Author(s):  
Hubert Sterba ◽  
Ralph L Amateis

Crown efficiency was first defined by Assmann (1961. Waldertragskunde. BLV, München) as individual tree volume increment per unit of crown projection area. He hypothesized that within a given crown class, smaller crowns are more efficient because their ratio between crown surface and horizontal crown projection is higher. Data from a loblolly pine (Pinus taeda L.) spacing experiment were used to test if this hypothesis also holds in young loblolly pine stands and, if so, to determine if it explains the increment differences between spacings in the spacing experiment. Using individual tree height relative to plot dominant height to describe crown class, within-plot regression showed that crown efficiency decreased with crown size for trees below dominant height. This relationship was much less pronounced than indicated from Assmann's examples, although the crown surface to crown projection ratio behaved in the same way as Assmann had hypothesized. Crown efficiency as well as the crown surface to crown projection area ratio decreased with increasing density. Basal area increment per hectare increased until total crown closure approached 130% and then stayed constant. This major impact of total crown coverage brings into question the usefullness of crown efficiency as an indicator for unit area growth.


2000 ◽  
Vol 24 (1) ◽  
pp. 31-36 ◽  
Author(s):  
Barry D. Shiver ◽  
John W. Rheney ◽  
Kenneth L. Hitch

Abstract A total of 141 paired plot installations remain of the 160 that were planted with slash (Pinus elliottii Engelm.) and loblolly (P. taedaL.) pine across southeastern Georgia and northern Florida, after 14 growing seasons. Installations were evenly distributed across eight soil types. Analyses indicate that loblolly performed equal to or better than slash pine. There were no soil X species interactions. After 14 yr, loblolly pine had significantly higher survival (71% vs. 66%), stand basal area (98 vs. 81 ft2/ac), total stand volume (1857 vs. 1721 ft3/ac), merchantable stand volume (1497 vs. 1310 ft3/ac), total green weight (53 tons vs. 47 tons), and merchantable green weight (45 vs. 35 tons/ac) than slash pine. Growth over the period from age 11 to age 14 was also higher for loblolly than for slash indicating that the difference in the two species is diverging over time. South. J. Appl. For. 24(1): 31-36.


1993 ◽  
Vol 17 (3) ◽  
pp. 135-138 ◽  
Author(s):  
Eric J. Jokela ◽  
Stephen C. Stearns-Smith

Abstract Data from six fertilizer trials established in semimature southern pine stands (five slash pine, Pinus elliottii Engelm. var. elliottii; one loblolly pine, Pinus taeda L.) were analyzed to determine the efficacy of single vs. split fertilizer treatments. Both fertilizer treatments supplied an elemental equivalent of 200 lb nitrogen (N)/ac and 50 lb phosphorus (P)/ac; however, the first treatment was delivered as a single dose, and the second treatment was a split N application (i.e., 50 lb N and 50 lb P/ac (initial); 150 lb N/ac (2 yr later). Cumulative responses of fertilized plots were still significantly greater than the controls in five trials after 8 yr and averaged 43% (15.7 ft²/ac) and 39% (607 ft³/ac) for basal area and stand volume growth, respectively. In general, no significant differences in either the magnitude or duration of response were detected between the single and split N fertilizer treatments. This suggests that delaying a portion of the N application for 2 yr will not diminish the level of growth responses attained. Therefore, land managers have flexibility in using either application method when implementing midrotation fertilizer prescriptions. South. J. Appl. For. 17(3):135-138.


2000 ◽  
Vol 30 (9) ◽  
pp. 1472-1475 ◽  
Author(s):  
David W MacFarlane ◽  
Edwin J Green ◽  
Harold E Burkhart

The height growth of dominant trees in plantations is often assumed to be independent of initial planting density. This assumption allows for the use of dominant tree height as an index of site quality. We found that this assumption was false for the seven tallest trees in 184 even-aged loblolly pine (Pinus taeda L.) stands, planted at nine initial planting densities, at four different geographic locations. A strong, highly significant negative correlation was found between dominant height and initial planting density for stands 14 and 16 years of age. This leads to large differences in predicted site index for stands with different initial planting densities planted at the same geographic location. Use of these site indices to predict yield produced large differences in predicted yield (m3/ha) at age 25. These results provide strong evidence for density-dependent height growth, even for dominant trees in the stand, and suggest that site index, used as a measurement of site quality, is confounded with stand density.


1982 ◽  
Vol 6 (1) ◽  
pp. 15-19 ◽  
Author(s):  
Howard W. Duzan ◽  
H. Lee Allen ◽  
R. Ballard

Abstract In a wide range of loblolly pine (Pinus taeda L.) plantations, very few of which were suffering from severe nutrient deficiencies, response to fertilization was related to stand conditions. Gross and net volume increment equations were developed using basal area, site index, and fertilizer treatment as predictor variables. Response to fertilization was calculated as the difference between growth estimates for control and fertilized stands at given levels of basal area and site index. Predicted 5-year volume response from fertilization with 100 lbs N/A + 50 lbs P/A is given for a range of basal area and site index levels for both the Coastal Plain and Piedmont regions. The information provided will enable the forest manager to choose stands with the greatest potential for response, and to determine the economic benefits of fertilization.


2009 ◽  
Vol 33 (4) ◽  
pp. 178-181 ◽  
Author(s):  
Kurt H. Johnsen ◽  
John R. Butnor ◽  
John S. Kush ◽  
Ron C. Schmidtling ◽  
C. Dana Nelson

Abstract Some evidence suggests that longleaf pine might be more tolerant of high winds than either slash pine (Pinus elliotii Englem.) or loblolly pine (Pinus taeda L.). We studied wind damage to these three pine species in a common garden experiment in southeast Mississippi following Hurricane Katrina, a very large, Category 3 hurricane that directly affected the stand in August 2005. The experiment, a factorial arrangement of silvicultural treatments established in 1960, included 120 plots of 100 trees each, covering about 22 ha. Following the hurricane, dbh was measured on all trees, and each tree was rated with respect to mortality from wind damage. Longleaf pine suffered less mortality (7%) than the other two species (slash pine, 14%; loblolly pine, 26%), although the differences in mortality were statistically significant only between longleaf pine and loblolly pine. Longleaf pine lost significantly fewer stems per hectare and less basal area than the two other species. Differences in mortality among species were not a function of mean plot tree height or plot density. Our analyses indicate that longleaf pine is more resistant to wind damage than loblolly pine.


2006 ◽  
Vol 36 (4) ◽  
pp. 953-960 ◽  
Author(s):  
Jianhua Qin ◽  
Quang V Cao

Data from 200 plots randomly selected from the Southwide Pine Seed Source Study of loblolly pine (Pinus taeda L.) were used to fit whole-stand and individual-tree equations. Another 100 plots, also randomly selected, were used for validation. Outputs from the individual-tree model were then adjusted to match observed stand attributes (number of trees, basal area, and volume per hectare) by four disaggregation methods: proportional yield, proportional growth, constrained least squares, and coefficient adjustment. The first three are existing methods, and the fourth is new. The four methods produced similar results, and the coefficient adjustment was then selected as the method to disaggregate predicted stand growth among trees in the tree list. Results showed that, compared to the unadjusted individual tree model, the adjusted tree model performed much better in predicting stand attributes, while providing comparable predictions of tree diameter, height, and survival probability. The proposed approach showed promise in the ongoing effort to link growth models having different resolutions.


1987 ◽  
Vol 11 (1) ◽  
pp. 28-31 ◽  
Author(s):  
M. W. Brown² ◽  
T. E. Nebeker ◽  
C. R. Honea

Abstract Twenty-seven 1-ac plots were thinned to a basal area of 70, 100, or 130 ft²/ac, and 9 plots were left unthinned to be used as a control. Changes in diameter growth, height growth, and oleoresin exudation pressure (OEP) are presented for the first 3 years following thinning. Height growth was lower in the thinned plots, but diameter growth in plots thinned to 70 and 100 ft²/ac was significantly greater than the unthinned plots and those thinned to 130 ft²/ac. OEP was also greater in thinned plots in the first two years; the difference was not significant in the third year. Introductions of southern pine beetles into the plots resulted in a significantly lower proportion of successful attacks in thinned plots in the first two years following thinning. It was concluded that increased tree vigor along with the increase in tree spacing following thinning does reduce susceptibility to southern pine beetle attack when stands are thinned to a basal area of 100ft²/ac or less. South. J. Appl. For. 11(1):28-31


1996 ◽  
Vol 20 (3) ◽  
pp. 121-126 ◽  
Author(s):  
Harold E. Quicke ◽  
Glenn R. Glover ◽  
Dwight K. Lauer

Abstract Objectives were to identify effective late-summer and spring herbicide treatments for the release of 3-yr-old loblolly pine (Pinus taeda L.) from competing hardwoods and to quantify longer term pine growth response to varying levels of hardwood control. Effective late-summer treatments included imazapyr at 1.0 and 0.5 lb ae/ac, imazapyr at 0.5 lb ae/ac in combination with glyphosate at 1.125 lb ae/ac, and imazapyr at 0.25 lb ae/ac with surfactant. The best spring treatment was hexazinone at 2.0 lb ai/ac. Although spring imazapyr treatments stunted pine height growth 2 growing seasons after treatment, height growth had recovered by age 10. Late-summer imazapyr treatments provided better hardwood control than spring treatments. Although check plot hardwood basal area averaged 9 ft2/ac, and winged elm (a species known to be tolerant to imazapyr) was the predominant hardwood species at treatment, pine basal area response to treatment ranged from 6 to 27 ft2/ac at age 10. Pine response increased with imazapyr rate for late-summer treatments. Adding hexazinone to imazapyr did not improve hardwood control, and no benefits were observed from adding metsulfuron to either glyphosate or hexazinone. South. J. Appl. For. 20(3): 121-126.


1986 ◽  
Vol 10 (2) ◽  
pp. 99-104 ◽  
Author(s):  
Wade C. Harrison ◽  
Thomas E. Burk ◽  
Donald E. Beck

Abstract Growth response of various species to thinning in even-aged stands of Appalachian mixed hardwoods was predicted with species-specific regression equations. Periodic annual increment over a five-year period was expressed as a linear function of original tree basal area divided by breast height age and a thinning or competition index based on stand basal area. For most species, a combination of stand basal area before and after thinning served as the thinning index; for the five oak species studied, the index was simply stand basal area after thinning. Nonlinear regression equations were formulated to express total tree height as a function of dbh and average height of dominant and codominant white oak. The equations for tree basal area increment and total height may be applied to predict growth after thinning in Appalachian mixed hardwood stands. South J. Appl. For. 10:99-104, May 1986


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