BULLETIN 362 NOVEMBER 1965N DEC1 7 19(65 Response ol Planted Loblolly Pine Following Varions conversion Methods Agricultural Experiment Station AUBURN E. V. Smith, Director FT1tRCT U NIVERSITY Auburn, Alabama CONTENTS INTRODUCTION ------ ----- ----- ----- ----- ----- ----- Page - 3 -3 LITERATURE REVIEW ------ --------------- S tu d y A rea - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 4 M E THOD S - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 6 R ES UL TS - - - - - - - - - - - - - - - -- - - - - - - - - - - - - - - - - - - - - - - 7 Su rvival - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- - - - - - - - - - - 7 Vigor Classes ---- ---- ---- ---- ---- -- - -- - 9 Height Growth -- -- -- -- - -- -- -- -- - -- -Diameters and Basal Areas------ -- -12 -13 V olu me - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- - - 15 Resurgence of Hardwoods---------------------------16' Cost E stim ates ------------- --- ------- -- ---------- 18 Comparison to Old-Field Plantation-------------------18 D ISCU SSIO N -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -- 21 SU M M AR Y -- - - - - - - - - - - - - - - - - - - - - -- - - - - - - - - - - - - - - - - - - - - 21 LITERATURE CITED ----------------------------------- 24 AP PE N DIX - - - - - - - - - - - - - - - - - - - - - -- -- - - - - - - - - - - - - - - - - - - - 25 FIRST PRINTING 3M, NOVEMBER 1965 Response of Planted Loblolly Pine Following Various Conversion Methods SHERMAN D. WHIPPLE and EDWIN H. WHITE Department of Forestry INTRODUCTION THE upland soils of Alabama's Upper Coastal Plain frequently are stocked with low-grade hardwoods that do not produce financial returns comparable to those produced by pine on similar sites. Various methods of converting hardwood stands to pine employed by progressive landowners in recent years have posed the question "What responses can be expected in survival and growth of planted loblolly pine (Pinus taeda L.) following various methods of conversion?" Because of the absence of literature on the early growth and development of pine stands after hardwood control treatments, a study of this problem was begun in 1959 on the Fayette Experiment Forest of the Auburn University Agricultural Experiment Station, (12). The objective was to test effects of seven methods. of conversion on survival and early growth of planted pine. LITERATURE REVIEW The literature is extensive concerning the initial success or failure of various hardwood control methods (1,5,6,9,10). Little information, however, can be found on early growth and development of pine following such hardwood control measures. Ferguson (2) indicated that planted loblolly pine increased in height for 2 or 3 years after release from competition with the increase proportional to the degree of release. His experimental design, however, precluded a rigorous analysis of the data. Mil- 4 ALABAMA AGRICULTURAL EXPERIMENT STATION ler (4) reported on the 9-year results of a study comparing 2 chemicals at 3 levels of concentration on the release of planted loblolly pine seedlings. He concluded that hardwood control was feasible as the data indicated that a moderately dense upland hardwood stand had been successfully converted to an established loblolly pine stand. Study Area The area involved in this study is situated in Fayette County near U.S. highway 43, 10 miles north of Fayette, Alabama in the Upper Coastal Plain soils region. It is an upland area on a gentle slope with a southern aspect. The soils are of the Ruston series and are deep, well-drained and moderately eroded. The profile is described as follows: 1- 6 inches, brown, very friable fine sandy loam; 6 - 20 inches, yellowish-red, friable fine sandy clay loam; 20- 49 inches, yellowish-red very friable fine sandy loam; and below 49 inches, strongly brown to red, sandy loam to light clay loam. Ruston soils tend to be low in fertility and available moisture. Loblolly pine site index ranges from 66 to 80 as determined by the Soil Conservation Service and these figures can be used as an approximate guide to the productivity of the area. Annual precipitation averages 53 inches per year, ranging from 40 to 75 inches. Mean annual temperature is 61.4 ° F. and the frost-free period averages 231 days. The original forest, Table 1, produced 1.5 cords of merchantable pine pulpwood per acre, 1,330 board feet of pine sawtimber, and 925 board feet of hardwood sawtimber per acre (Inter. 1/4inch rule). Most hardwood sawtimber was of poor quality. Pine stocking and growth were low. Consequently, the full productive capacity of the area was not being realized. The upper canopy was sparse but the largely hardwood understory canopy, consisting of miscellaneous shrubs, seedlings and sprouts of oak (Quercus spp., L.), hickory (Carya spp., Nutt.), sweetgum (Liquidambar styraciflua, F.), black gum (Nyssa sylvatica, Marsh.), red maple (Acer rubrum, L.), dogwood (Cornus florida, L.), persimmon (Diospyros virginiana, L.), and sourwood (Oxydendrum arboreum, DC.), plus many muscadine grape vines (Vitis rotundifolia, Michx.) was dense. Pine in the understory was noticeably absent. rn 0 TABLE 1. CONDITIONS ON STrUDY AREA PRIOR TO CUTTING On TREATMENT Stocking (per 123 m Volume (per acre) Sawtimber Number 19 31 Basal Area (per acre) Sawtimber acre) Sawtimber Bd.Ft. 1,33 0 0 - Species Sprouts and seedlings Number Pine Small saplings Number 2 351 62 Pulpwood Number 0 122 28 Small saplings Pulpwood Pulpwood Cords 1.5 Sq.Ft. 0 9.88 2.17 Sq.Ft. 6.09 Sq.Ft. 13.27 z m Hardwoods shrubs oak and hick. 30 1,750 2,643 2,042 0 13 1 0 17.03 8.62 0 11.60 0.38 0 9C 2 Misc.' )2 6,435 415 150 Subtotal Grand Total 6,435 4.5 181 ' Based on 1958 statistics. 2 Sprouts and seedlings-i' high, 1" d.b.h. Small saplings-i.l" d.b.h. to 3.5" d.b.h. Pulpwood-3.5" d.b.h. and greater. 3Blanks in table indicate that data was not available. 14 33 12.05 12.05 25.65 31.74 11.98 25.25 1.5 92 22 'Miscellaneous species; sweetgum, blackgum, red maple, and semitrees such as dogwood, sourwood, and persimmon. U'1 6 ALABAMA AGRICULTURAL EXPERIMENT STATION METHODS A randomized block design, consisting of 7 treatments (including an untreated check) with 5 replications per treatment, was established under comparatively uniform stand conditions. Treatment plots were square, 132 feet on each side, with a 46.2 foot x 46.2 foot permanent sample plot located in the center of each treated plot. This left an isolation strip of 85.8 feet between sample plots. One year prior to hardwood control treatments a sale, averaging 2,255 board feet of sawtimber and 1.5 cords of pine pulpwood per acre, was made of all merchantable timber. The treatments were as follows: 1. Check - No hardwood control measures were applied. 2. Scarification by bulldozer - With the bulldozer blade at ground level, all stems were pushed over or uprooted and all slash windrowed. 3. Injector-applied herbicide - Stems one inch d.b.h. and larger were injected around the base at one inch spacing except for hickory and maple that received a frill of injections. An herbicide was applied in a 1-to-12 ratio with diesel fuel. 4. Girdle without herbicide - Stems 1 to 3 inches d.b.h. were cut at waist height. Stems over 3 inches d.b.h. were axe girdled, chipping out a 3-inch strip, of bark and cambium. 5. Axe frill and herbicide - Stems 1 to 3 inches d.b.h. were cut at waist height. Stems over 3 inches d.b.h. were single axe frilled with an axe. An herbicide in a 1-to-30 ratio with diesel fuel was applied to all cut surfaces with an oil can. 6. Chain girdle and herbicide - Stems cut at waist height. Stems over 3 inches a Brady Handy Girdler. 2 Herbicide in a fuel was applied to all cut surfaces with 1 to 3 inches d.b.h were d.b.h. were girdled with 1-to-30 ratio with diesel an oil can. 7. Foliage spraying plus axe frill and herbicide - Spray was applied from a tractor-mounted device through a three-nozzle, 1 The herbicide used in treatments 8, 5, 6, and 7 was a Dionoxol compound of half 2,4-D and half 2, 4,5-T at a concentration of 4 pounds of acid equivalent per gallon. 2 Joe Brady and Associates, Birmingham, Alabama. Trade name and company are included for the benefit of the reader but do not imply any endorsement by the Auburn University Agricultural Experiment Station. RESPONSE OF PLANTED LOBLOLLY PINE 7 12-foot "A" frame. Approximately 60 gallons per acre were applied in a ratio of 1 part herbicide, 2 parts diesel fuel and 57 parts water. This was about twice the rate of application currently considered best for foliage spraying. Stems over 4 inches d.b.h. were axe frilled and herbicide in a 1-to-30 ratio with diesel fuel applied to cut surfaces with an oil can. In January 1959, each treatment plot was planted with loblolly pine seedlings. These were 1-0 seedlings which averaged 1 foot in height. The spacing was 6 by 9 feet and resulted in 35 seedlings per sample plot. Treatment two was applied in January 1959 prior to planting and treatments 3 through 7 were applied after hardwood leaves had fully developed in the spring of 1959. Total heights and numbers of surviving pine were determined and recorded after each growing season for 6 years after treatment. All hardwood reproduction was counted on 4 one-milacre subplots which were randomly 3 located in each sample plot replication. The sixth year after treatment the diameters breast high of all surviving pines with heights greater than 41/2 feet were measured and recorded. Furthermore, all the surviving pines were tallied by the following vigor classes: Excellent - Dominant, free to grow, well-formed trees with a minimum live crown ratio of 1:2. Good - Dominant and codominant trees with a minimum live crown ratio of 1:3. Fair - Intermediate trees partially suppressed by hardwoods. Poor - Deformed and/or overtopped trees. Standard statistical methods were used to analyze the data, (7). RESULTS Table 2 summarizes the mensurational data for the seven treatments. Survival Analysis of variance of the numbers of surviving pine indicated significant differences among the various treatments 6 years after they were established (Appendix Table 1). The order of signifi3The permanent sample plots encompassed 49 milacres and a table of random numbers was used to select 4 one-milacre subplots for measurements. TABLE 2. MENSUJRATIONAL DATA SIX YEARS AFTER PLANTING, ON A PER ACRE BASIS Treatment S urvivals data Sum heights of' Heights' Av. height 4 Standard deviation Annual' growth Diameters 2 Annual Av. d.b.h. growth 2 B area aa No. 1. 2. 3. 4. 5. 6. Description Check .(no treatment) Bulldozer scarification Injected herbicide Girdle only (no herbicide) Axe frill with herbicide Chain frill with herbicide Foliage spray (plus treatment Number 498 625 600 535 608 Per cent 69.7 87.4 84.0 74.9 85.1 81.7 58.7 Feet 2,834.9 9,819.3 8,023.2 6,594.5 8,911.0 8,339.5 Feet 5.7 15.7 13.4 12.3 14.7 14.3 11.9 Feet ±*3.1 ±3.1 ±3.6 ±3.7 ±3.9 ±2.9 Feet 0.8 2.4 1.0 1.8 2.1 2.0 1.7 Inches 0.5 2.5 1.9 1.6 2.2 2.1 1.6 Inches 0.07 0.38 0.27 0.23 0.31 0.30 0.23 Sq.Ft. 0.857 24.410 13.532 9.062 18.226 14.552 6.715 0 X C C 7- 7. 584 384 5 on overstory) 4,573.9 ±4.5 ' Live, planted stems only. Live, planted stems over 4.5 feet in height. ' The sum of the total heights of all trees by treatment. by dividing the sum of heights figure by survival number. ' Determined by dividing average heights per tree by 7 (growing years). 'Determined m x z -I m m In -I Iz RESPONSE OF PLANTED LOBLOLLY PINE 9 650 O. 650 ____ I---K I 7. ""-7. ... 0""" Foliage Spray In1--e PIU Lr oig plus Treatme nt 5 2ide v C, ~S **. *0- 600 550 5 \ S---- - ---- n------------ __ o----06 0--- ---------- Z '500 *.0 C z 450 400....................................0 350 0 0 I 2 3 4 5 6 . o Years Since Planting FIG. 1. Number of surviving loblolly pine seedlings for six years after planting. cant differences (P < 0.01) as indicated by Hartley's sequential range test (7) was: 4 Treatment: 2 5 3 6 4 1 7 Mean No. pines per acre: 625 608 600 584 535 498 384 Pine survival 6 years after hardwood control treatments were established ranged from a high of 87.4 per cent for treatment 2 to a low of 53.7 per cent for treatment 7. The bulldozer scarification, injector-applied herbicide, axe frill and herbicide, and chain girdle and herbicide treatments resulted in 25.4, 20.5, 22.1, and 17.2 per cent, respectively, greater-numbers of surviving planted pines 6 years after treatment than did the check treatment. Data of treatment 7, foliage spraying, indicated a significant decrease of 23.0 per cent (P < 0.01) in pine survival over the control. This latter difference is attributed to mortality this report, all means and treatment numbers not underscored by the same line differ at the 0.01 level of significance. In 10 ALABAMA AGRICULTURAL EXPERIMENT STATION of the pine in the first year after treatment, resulting from heavy dosage of herbicide spray applied to the area, Figure 1. The high rate of mortality could have been avoided had foliage spraying been done prior to planting. Data from other studies indicate that mist blower application of low volumes with high concentrations would have resulted in less pine mortality, (9). Analysis of the data for numbers of surviving pine did not indicate a significant treatment and year interaction term following the first year's mortality. However, mortality was greatest the first year after planting, ranging from a low of 5.7 per cent under treatment 2 to a high of 38.3 per cent under treatment 7. In the following 5 years pine mortality on scarified plots and herbicide plots was very small. In the check plots and the "girdle only" plots pine mortality was appreciable, Figure 1. Vigor Classes Figure 2 indicates the number of pine seedlings per acre by vigor class for each of 7 treatments. Analysis of variance (Appendix Table 2) of the number of seedlings classified as excellent indicated significant differences (P < 0.01) between treatments. Hartley's range test indicated the order of significant differences to be: 1 7 3 4 6 2 5 Treatment: 502 392 367 286 189 127 20 Mean No. of stems: The best treatment, scarification, resulted in 25.1 times as many excellent stems per acre as the control treatment. The other treatments, 3 through 7, varied from 19.6 to 6.3 times greater abundance over the control; all showed a significant increase as indicated. Combining the number of excellent and good vigor stems on each treatment indicates stands of 93, 563, 453, 335, 523, 510, and 237 stems per acre for treatments 1 through 7, respectively, that are in a position for future development. Treatments 1, 3, and 4 all have substantially more trees in the fair and poor vigor classes as a result of no hardwood control (treatment 1) or increasing hardwood competition because of ineffective control (treatments 3 and 4). For the first 2 years after treatment the pine seedlings on the bulldozer plots exhibited chlorotic yellowing of the foliage plus 500 0 Vigor Classes m 0 0 LIExcellent 400 ® Good z 0. U) C '0) 0l) C E D3 300 Fair z m 0 w r0 Poor .> (I 4- 200 z m 0 100 E z 0 -Y :iD 2 HH-H r." --.- ."IXXI ___" :a: ::a [." .IY II: .7 :.:......... ... .. 3 4 5 6 7 TREATMENT FIG. 2. Number of pine surviving after six years, by vigor class and treatment. Em.1 N.A 12 ALABAMA AGRICULTURAL EXPERIMENT STATION reduced height growth as compared to other treatments. The visual symptoms were typical of a nitrogen deficiency (11) and, although no chemical analyses were made, the condition was attributed to the loss of nitrogen and organic matter as a result of the scarification. Height Growth Average heights of pine stems on treated plots ranged from 2.0 (treatment 7) to 2.8 (treatment 2) times greater than on the untreated check plot (treatment 1). Analysis of variance of the mean height growth data (Appendix Table 3) with Hartley's range test indicated the following significant differences (P < 0.01) existed between treatments 6 years after hardwood control measures were begun: 1 3 4 7 5 6 2 Treatment: 15.7 14.7 14.3 13.4 12.3 11.9 5.7 Mean height (feet): All hardwood control treatments resulted in significantly greater height growth than did the check (treatment 1). The pine seedlings developing on treatment 2, scarification, showed more uniformity in height than did stems on the other treatment plots at the end of the 1964 growing season. This is illustrated by the coefficient of variation values, wherein standard deviation of height is expressed as a percentage of respective mean height. These values are 53, 20, 27, 30, 27, 21, and 37 per cent respectively for treatments 1 through 7. In proportion to their significantly larger size, pine stem height variation was considerably less under treatment 2 than under most other treatments. This difference can, in part, be attributed to ineffective hardwood control measures. After the 1959 growing season, annual height growth increased on all treatments for 2 years, Figure 3, and then tended to remain stable or decrease for treatments 1, 3, 4, and 7 while increasing for treatments 2, 5, and 6. Figure 3 indicates that the average annual height growth of seedlings on the check plot was always 1 foot or less. On all other plots, after the initial year of establishment, seedlings averaged almost 2 feet and in some cases, i.e., treatment 2, 3 feet per year. A significant treatment and year interaction was also indicated by the analysis of variance date (P < 0.01). This indicates that the treatment effects resulted in different patterns of height re- RESPONSE OF PLANTED LOBLOLLY PINE 13 sponses from year to year. Part of the significant treatment and year interaction is explained by the annual height growth decreasing on plots where hardwood control was ineffective or is diminishing. For example, treatment 4, girdling only, resulted in a quick release of the pine and early rapid height growth that was again suppressed by the numerous sprouts that developed from girdled stems, Figure 3. Analysis of variance (Appendix Table 4) along with the following multiple comparisons of the number of live hardwood stems 1 inch and greater d.b.h. on treatment plots, indicated that significantly greater numbers (P > 0.01) of hardwood stems were live on treatment 4, girdle only, than on the herbicide treated plots: Treatment: Mean No. per acre: 6 5 7 5 1 3 4 1150 1100 400 350 200 200 50 Observations indicated that herbicide treated stems did not sprout as profusely as did stems girdled only and therefore released pine were able to continue early rapid growth, Figure 3. Another part of the interaction is explained by the relatively poor early height growth of the pine seedlings on the scarified plot caused by the loss of nitrogen and organic matter. These pines eventually surpassed other pines in growth. This same effect was observed on treatment 7 when the early height growth was suppressed by the heavy volume of herbicide applied. Both of these conditions were reflected in the growth patterns demonstrated by Figure 3. Diameters and Basal Areas Average diameters breast high of each treatment are summarized in Table 2. Analysis of variance (Appendix Table 5) and Hartley's range test indicated the following order of significant differences (P < 0.01) between the various treatments: 1 7 4 6 3 5 2 Treatment: 2.5 2.2 2.1 1.9 1.6 1.6 0.5 Mean d.b.h. (inches): The order of response was identical to the order in height growth, Figure 3. All hardwood control treatments resulted in significantly greater diameters than did no hardwood control, ranging from a low of 3.2 (treatment 7) to a high of 5.0 times (treatment 2) greater. 4.0 3. + Injected Herbicide Girdle Only 4.----3.0 5.----A Axe Frill and Herbicide 6.----o Chain Frill and Herbicide// -" -\a. .- x2 \ 7"".0"""oFoliage Spray plus Treatment 5 "- j - 5 + 1.5W oA ......... 1.0. LAI- Fildm 0 01 05 1958 1959 1960 1961 1962 1963 1964 Growing FIG. 3. Seasons Z Average annual height growth of planted loblolly pine by treatment. RESPONSE OF PLANTED LOBLOLLY PINE 15 Basal area per acre indicated large differences between treated plots and the control although the order of significant differences, as indicated by analysis of variance (Appendix Table 6) and multiple comparisons, was the same as the orders of differences observed for mean heights and mean diameters, i.e.: Treatment: 2 5 6 3 4 7 1 Mean BA per acre (sq. ft.): 24.4 18.2 14.6 18.5 9.1 6.7 0.9 Six years after hardwood control treatments were applied treatment 7 had 7.4 times greater basal area than the control, while treatment 2 had 27.1 times greater. Volume Multiplying the basal area of each tree greater than 0.8 inches d.b.h. by the corresponding height and summing for each treatment plot to give an approximate index of volume, Table 2, indicated that the treated plots had a large superiority over the untreated check plot and also that large differences existed between treatments themselves. Analysis of variance of per acre volumes (Appendix Table 7) and Hartley's range test indicated the following order of significant differences (P < 0.01) between the various treatments: Treatment: 2 5 6 3 4 7 1 Mean vol. per acre (cu. ft.): 421.5 308.0 230.6 207.8 181.0 108.4 10.4 Treatment 2 had approximately 1.5 to 40.5 times more cubic foot volume per acre than the other treatments. All hardwood control treatments resulted in volumes significantly greater than did no hardwood control treatment ranging from 10.4 times (treatment 7) to 40.5 times greater (treatment 2). In an attempt to illustrate early stand development, the volume index data indicate the greatest differences between treated plots and the control although the order of differences was the same as the order observed for mean heights, mean diameter, and mean basal area. The number of significant differences, however, was greater with the volume data than with the other mensurational data. Only treatments 6 and 3, and treatments 4 and 7 were indicated as similar with the volume analysis while the other mensurational data analysis indicated that numerous treatments were similar. The above data indicate that although mean height, 16 ALABAMA AGRICULTURAL EXPERIMENT STATION mean diameter, and mean basal area data are necessary and important in understanding early stand development, the best criterion from the present study for assessing early stand development is total cubic foot volume which encompasses all measurements into one. Resurgence of Hardwoods None of the hardwood control treatments applied in this study completely eradicated hardwoods. However, the number of hardwood stems competing with pine was significantly reduced by scarification and herbicide treatments. This was evident not only from number of hardwood stems remaining but by response of the pine in height, diameter, survival, volume, and basal area. Figure 4 shows the total number of hardwood stems by size classes present at the end of the fifth growing season. The greatest numbers occur on plots where the overstory stand was more completely killed, i.e., treatments 2, 3, 5, and 6. However, most of the stems, 60 to 80 per cent, were under 4 feet in height and offered little competition to the pine. The scarification plots had the greatest total resurgence of hardwood but 83 per cent of these were under 4 feet in height and 99.6 per cent were under 1 inch in d.b.h. Thus the data indicate that the understory hardwoods, as well as the pine, responded to a release from the competing overstory. The girdle only treatment (treatment 4) resulted in an immediate kill of the treated stems but sprouting was so profuse that any advantage gained by the girdling was quickly overcome. Treatment 7, foliage spraying, actually had less hardwood stems after 5 growing seasons than did the check plot. However, the adverse effect of the spray on the young pine and the size of the existing hardwood stems 5 retarded the development of the pine. The linear correlation coefficient (r) between numbers of hardwood stems greater than 1 inch d.b.h. and total cubic foot volumes was 0.88, significant at the one per cent level6. This correlation indicates that larger hardwood stems were the most serious competitors with the pine, as the fewer the number of hardwoods over 1 inch d.b.h., e.g., on treatment 1, the greater was the total volume of pine. SMany stems over 25 feet in height but less than 4 inches d.b.h. were unaffected by treatment. 6 Data of treatment 7 are deleted from this analysis since height growth of pine had been so adversely affected by foliage spray. m .0 U O O. U) z 0 H z -I m 0 .c C 0 I- 0 FF- E 0 0 0 (0 0 .0 E Z Treatment FIG. 4. Number iV Number of hardwood stems by treatment and size class five years after treatment. 18 ALABAMA AGRICULTURAL EXPERIMENT STATION An adverse effect of the hardwood control treatments was the influx of muscadine grape and other vines into the plots. The weight of these vines often resulted in deformed pine stems and even death of some trees. Cost Estimates Table 3. shows initial cost per acre for establishing each treatment. Planting costs, including the cost of both seedlings and planting, were $14 per acre for all treatments except scarification, which was $12 per acre because of the greater ease of planting on open ground. Total costs ranged from $14 per acre for the check to $25 per acre for the foliage spraying treatment. The initial costs per acre are shown compounded for 6 years at 6 per cent interest in Table 3. Dividing this compound cost by the sum of all heights per plot and multiplying by a factor of 10 gives the cost per 10 feet of height growth. Expressed in this manner, costs per 10 feet of height growth were least for treatments 2, 3, and 5 and approximately twice as great for treatments 1 and 7 with other treatment costs falling between these extremes, Table 3. It was felt by the authors that an expression of compounded cost in terms of resulting growth would yield more realistic comparison figures than would costs alone. Comparison to Old-Field Plantation In an attempt to compare the development of plantations established under hardwood control treatments with development of an old-field plantation, 15 trees from a 15-year-old loblolly plantation, established on an old field, were sampled by standard stem analysis procedures. The old field was on the same soil type and had the same aspect as the hardwood control study area and consequently, was assumed to have comparable site conditions. Stems were sampled from a range of diameters and a height over age curve plotted. Linear regression lines of the form Y - bX + a, where Y - height, and X = age, were derived from these data and the data of the current study, Figure 5. The correlation coefficients (r) between age and average height for each of these situations, are reported to indicate the degree of relationship between height and age at this early age (Appendix Table 8). These data imply that plantations developed under hardwood control treatments were not equal in development to an old-field CA m 0 z m 0 o TABLE 3. TIME AND COST OF TREATMENT ON A PER ACRE BASIS r- Time Treatment Treat. Plant. Equip. Labor and equip. Hr. 10.00 19.67 13.16 14.37 15.41 16.89 12.94 Materials Chem. Dol. 0.003 0.00 2.56 0.00 0.94 1.15 8.57 Plants Dol. 4.00 4.00 4.00 4.00 4.00 4.00 4.00 Cost Total Time and material Dol. 14.00 23.67 19.72 18.37 20.35 22.04 25.51 z -i m C .to Comp. to 6 yrs. Dol. 19.864 42.48 35.39 32.97 36.53 39.56 45.79 Per 10 ft. of height o g h growth Dol. 0.070 0.043 0.044 0.050 0.041 0.047 0.100 0 0 r r- w 0I- No. Description 1. Check (no treatment) 2. Bulldozer scarification 3. Injected herbicide 4. Gridle only (no herbicide) 5. Axe frill with herbicide 6. Chain frill with herbicide 7. Foliage spray (plus treatment 5 on overstory) 1 Hr. 0.00 3.85 3.16 4.37 5.41 6.89 2.36 Hr. 10.01 8.0 10.0 10.0 10.0 10.0 10.0 Hr. 0.002 2.61 0.00 0.00 0.00 0.00 0.19 Z z m -- -- All labor charged at $1.00 per hour. 2 Equipment involved the use of a caterpillar tractor (RH-4) and the operating cost was set at $3.00 per hour, not including operator. Chemical cost $6.09 per gallon and diesel fuel $0.12 per gallon. 4 Compound interest rate of 6 per cent. 20 ALABAMA AGRICULTURAL EXPERIMENT STATION 25 20 Old Field 0x2 e 15 -4 -U S3,5,6 c E . 10 / * 00 3 4 5 6 7 Age (years) FIG. 5. Comparisons of early height growth between an old field plantation and the experiment plantation receiving hardwood control treatments. plantation of the same age, species, and site. The average height of stems on the best hardwood control treatment, scarification, was only 78 per cent as tall as the average height of stems from the old-field plantation. The advantage of the old field can probably be attributed to residual fertility from past land-use practices and, because there were no competing hardwoods, more available moisture. The average heights of pine on the other hardwood control treatments ranged from 27 per cent to 71 per cent as tall as the average height of the stems of the old-field planting. RESPONSE OF PLANTED LOBLOLLY PINE 21 DISCUSSION Much of the variation in survival and growth of the planted pine can probably be explained by variations in available soil moisture, soil nutrients, and light as influenced by the degree of hardwood control achieved by various conversion procedures. The best development of planted pine was on scarified plots (treatment 2) and, although it is not known whether or not the differences in development resulted from variations in light, nutrients, and moisture, it is not unreasonable to assume that all contributed to the development of pine. Other studies have indicated similar effects of hardwood competition on light and soil moisture availability, (3,13). Data from the present study indicate that pine planted under treatments that were only partially effective in hardwood control, i.e., treatment 4, girdle only, are in need of release if the planted pines are to adequately survive and develop to produce a fully stocked stand. However, the preceding data and field observations indicate that treatment 2, scarification, treatment 3, injector-applied herbicide, treatment 5, axe frill and herbicide, and treatment 6, chain girdle and herbicide, have resulted in conditions that are now ready to support relatively well-stocked vigorous pine stands of much greater value than the pre-existing hardwood cover. SUMMARY Data presented indicate that various hardwbod control techniques can be used to convert low-value hardwood stands to higher value pine stands on upland sites at costs not unreasonable. The data suggested that, although height, diameter, survival, and basal area data are necessary in depicting early development of plantations, they may be misleading and not entirely complete. Total cubic foot volume data gave the most accurate picture of early stand development in this study. Data on early growth and development of planted loblolly pine following various hardwood conversion procedures are presented. Bulldozer scarification, injector-applied herbicide, axe frill and herbicide, and chain girdle and herbicide show the most promise as methods of converting hardwood stands to vigorous pine stands. It is suggested that anything less than a complete removal of hardwoods (at least to 22 ALABAMA AGRICULTURAL EXPERIMENT STATION one inch diameter at groundline) will result in the need for a hardwood cleaning to release the pine soon after the initial treatment. Variations in survival and growth of the planted pines are attributed to variations in available soil moisture, nutrients, and light as influenced by the degree of hardwood control achieved by the various conversion procedures. In comparing the development of the hardwood control treated stands with an old-field plantation it was found that the treated stands were not developing as rapidly as were nearby older plantings in an old field at an equivalent earlier time. RESPONSE OF PLANTED LOBLOLLY PINE 23 FIG. 6. Stand conditions six years after treatment of a check plot, upper left; bulldozer scarified plot, upper right; herbicide treated plot, lower left; and girdle only plot, lower right. 24 ALABAMA AGRICULTURAL EXPERIMENT STATION LITERATURE CITED (1) CAMPBELL, R. S.; PEEVY, F. A. Chemical Control of Undesirable Southern Hardwoods. Jour. Range Mgt. 3: 118-124. 1950. (2) (3) E. R. Response of Planted Loblolly Pines to Reduction of Competition. Jour. For. 56:29-32. 1958. FERGUSON, McCORMACK, M. L., KORSTIAN, C. F. Conversion of Post Oak-Black- jack Oak Type to Pine in the North Carolina Piedmont. Jour. For. 61:445-446. 1968. (4) MILLER, W. D. Development of Planted Loblolly Pine in a Poisoned Upland Hardwood Stand of the Lower Piedmont. Jour. For. 59:184186. 1961. (5) PEEVY, F. A. Controlling Southern Weed Trees with Herbicides. Jour. For. 58:708-710. 1960. (6) R. D. Effects of Season of Treatment on Girdling and Chemical Control of Oak and Sweetgum. Jour. For. 56:33-35. 1958. SHIPMAN, (7) SNEDECOR, G. W. Statistical Methods. Iowa Sta. Coll. Press, Ames, Iowa. 1956. (8) Soil Conservation Service. Fayette County, Alabama, Soil Survey Report. (Unpubl. Ms.). 1964. (9) STARR, J. W. The Use of the Mist Blower for Control of Undesirable Hardwoods. Miss. Sta. Univ. Exp. Sta. Bull. 692. 1964. (10) STRANSKY, J. J. Concentrated or Diluted 2,4,5-T as a Supplement to Girdling? Jour. For. 57:432-434. 1959. (11) WALLACE, T. The Diagnosis of Mineral Deficiencies in Plants. A Color Atlas and Guide. 2nd Ed., H. M. Stat. Office, London. 1951. (12) WHIPPLE, S. D., Survival and Growth of Planted Pines after Stand Treatment. Highlights of Agri. Res., 9:3, Fall, Agri. Expt. Sta., Auburn Univ., Auburn, Ala. 1962. (13) Soil Moisture-Seedling Growth Relations in Conversion Planting of Oak Ridges to Pine. Jour. For. 59:20-23. 1961. WILLISTON, H. L., McCLURKIN, D. C. RESPONSE OF PLANTED LOBLOLLY PINE 25 APPENDIX APPENDIX TABLE 1. ANALYSIS OF VARIANCE OF NUMBERS OF SUIVING LOBLOLLY PINE SIX YEARS AFTER PLANTING Source of variation D.F. Sum of squares Mean square 5,175.524 209 Total .----------------- ----------------67.762 275.048 4 Replications (R) ---------------------492.9651 2,957.791 6 Treatments (T) -----------------------55.056 1,321.351 24 Error (a) RXT-----------------------66.3621 5 331.810 Year (Y ) -----------------------------------1.957 58.723 30 T X Y .X-----------------_--------Y------1.649 230.801 140 Error (b)RX Y+RXYX T---_. 1 Denotes significance at the 0.01 level. APPENDIX TABLE 2. ANALYSIS OF VARIANCE OF NUMBERS OF EXCELLENT VIGOR LOBLOLLY PINE SIX YEARS AFTER PLANTING Source of variation D.F. Sum of squares Mean square 12.671 359.7901 34 2,621 .543 T otal ---------------------------------------50.686 4 Replications ------------------------------6 2,158.743 Treatments ------412 .114 24 ---------------------------------Error - --- 1Denotes significance at the 0.01 level. APPENDIX TABLE 3. ANALYSIS OF VARIANCE OF MEAN HEIGHTS OF LOBLOLLY PINE SIX YEARS AFTER PLANTING Source of variation D.F. Sum of squares Mean square 1.130 Total --------------------Replications (R) 6 24 -------------------- 5 Year (Y) 30 T X Y -------------------140 Error (b) RX Y±RXY XT_-. 1'Denotes significance at the 0.01 level. Treatments (T) -----------Error (a) RXT------------APPENDIX TABLE 4. ----------- 209 4 4,062.730 4.530 496.230 139.890 3,120.290 78.2001 5.830 624.0601 232.690 69.100 7.7601 0.490 ANALYSIS OF VARIANCE OF THE NUMBER OF HARDWOOD STEMS 1.1 INCHES D.B.H. Source of variation D.F. 34 4 Sum of squares Mean square 1.750 Total ------------- ------------ Treatments----------------Error------------------- -- Replications ---------------- 207 7 6 24 96 104 16.000' 4.333 'Denotes significance at the 0.01 level. 26 ALABAMA AGRICULTURAL EXPERIMENT STATION APPENDIX TABLE 5. ANALYSIS OF VARIANCE OF MEAN DIAMETERS OF LOBLOLLY PINE SIX YEARS AFTER PLANTING BREAST HIGH Source of variation D.F. Sum of squares Mean square 0.102 3417.000 8--------------------------------Total 0.410 4 Replications-----------------Treatments----------------6 13.190 3.400 Error ---------------------------------------24 1 Denotes significance at the 0.01 level. 2.1981 0.142 APPENDIX TABLE 6. ANALYSIS OF VARIANCE OF MEAN BASAL AREA PER PLOT OF LOBLOLLY PINE SIX YEARS AFTER PLANTING Source of variation D.F. Sum of squares Mean square To tal ---------------------------------------Replications------------------ Treatments ._---------------1 - 34 4 6 5.70 3 0.210 4.333 1.160 0.052 0.7221 0.048 E rror .--------------------------------------24 Denotes significance at the 0.01 level. TABLE 7. ANALYSIS OF VARIANCE OF CUBIC FOOT VOLUMES OF LOBLOLLY PINE SIX YEARS AFTER PLANTING APPENDIX Source of variation T otal----------------------------------------Replications----------------Treatments .-----------Error 1 D.F. 34 4 6 24 Sum of squares 1,859.366 65.451 1,337.890 456.025 Mean square 16.363 222.9821 19.001 Denotes significance at the 0.01 level. APPENDIX TABLE 8. REGRESSION COEFFICIENTS AND CONSTANTS FOR REGRESSION EQUATIONS AND CORRELATION COEFFICIENTS FOR DATA BETWEEN HEIGHT AND ACE OF LOBLOLLT PINE FROM AN OLD-FIELD PLANTATION AND HARDWOOD CONTROL TREATMENTS (r) Treatments b 3.02 2.57 2.14 0.90 2.24 3.25 a 5.52 3.78 2.36 0.52 3.62 -2.72 r 0.999 0.994 0.997 0.999 0.922 2 .--------- -----3, 5, 6'-------------4----------------1----------------7---------------old. 1 field --------------- Since average heights of pine were similar under herbicide treated plots, one regression was derived from the combined data of treatments 3, 5 and 6.