- Email: [email protected]
Fertilization response in a natural bottomland hardwood stand in north-central Louisiana
Forest Ecology and Management 114 (1999) 261±264
Fertilization response in a natural bottomland hardwood stand in north-central Louisiana Michael A. Dunn1,a,*, Kenneth W. Farrishb, John C. Adamsc b
a LSU Agricultural Center, Louisiana Cooperative Extension Service, P.O. Box 25100, Baton Rouge, LA 7894-5100, USA Arthur Temple College of Forestry, Stephen F. Austin State University, P.O. Box 6109 SFA Station, Nacogdoches, TX 75962-6109, USA c Professor of Forest Genetics and Silviculture, School of Forestry, Louisiana Technical University, Ruston, LA 71272, USA
Abstract The effect of nitrogen and phosphorus fertilization on growth of a natural bottomland hardwood stand in north-central Louisiana was evaluated. A typical mixed stand of pole-sized and small saw-timber bottomland hardwoods with about 23.7 m2 haÿ1 of basal area was used in the study. Soils were Guyton silt loam (Fine-silty, siliceous, thermic Typic Glossaqualf). Three fertilizer treatments plus a control were replicated three times on 0.1 ha plots. The treatments consisted of nitrogen (168 kg haÿ1) as ammonium nitrate, phosphorus (56 kg haÿ1) as triple super phosphate, and NP. Trees greater than 10 cm at dbh were measured for diameter before fertilization and remeasured after one and two growing seasons. Diameter increment served as the response variable. Results showed a statistically signi®cant (p<0.05) increase (70 pct greater than the control) in diameter growth for the 2 year total increment on the NP treatment with all species combined. While the small sample size and relatively high amount of variability resulted in no further statistical signi®cance among the treatments, the data did reveal trends that need further investigation. Sweetgum (Liquidambar styraci¯ua L.) responded to N alone, while the oaks (Quercus), especially the white oaks, responded to P alone. The oaks also responded to NP, while no similar response was seen from sweetgum for that treatment. # 1999 Elsevier Science B.V. All rights reserved. Keywords: Fertilization; Hardwoods; Sweetgum; Liquidambar styraci¯ua; Red oaks; White oaks; Quercus
1. Introduction To keep pace with increasing demands for its products, the forest products industry continues to seek new ways to increase wood and ®ber production from forests. In northern Louisiana, new capacity in the oriented strand board industry coupled with increased demand for speci®c qualities of paper in *Corresponding author. 1 Formerly Research Assistant, School of Forestry, Auburn University, Auburn, AL, USA.
the paper products industry have lead to an overall increase in demand for hardwood ®ber. This has resulted in interest in increasing productivity of hardwood forests in the region. From March 1994 to November 1996, a study was conducted in north-central Louisiana to determine the effect of nitrogen and phosphorus fertilization on growth of bottomland hardwood species in natural stands. A previous study in the region had shown that from 25- to 30-year-old loblolly pine (Pinus taeda L.) plantations responded well to nitrogen and phosphorus fertilization on upland sites (Williams and Farrish,
0378-1127/99/$ ± see front matter # 1999 Elsevier Science B.V. All rights reserved. PII: S0378-1127(98)00357-0
262
M.A. Dunn et al. / Forest Ecology and Management 114 (1999) 261±264
1994). However, very little research has been conducted into the possible growth response from fertilization of naturally established bottomland hardwood stands on minor stream bottoms in the region. In fact, very little research regarding hardwood fertilization has been conducted in the southern United States, especially on natural stands. Miegroet et al. (1994) evaluated the effect of various N (urea) fertilizer regimes on an American sycamore (Plantanus occidentalis L.) plantation. Their ®ndings indicated that a treatment in which N was applied in increasing amounts as trees accumulated biomass was optimum in increasing stem biomass production and reducing potential groundwater contamination. Nelson and Switzer (1990) performed ®eld research into the response of sweetgum (Liquidambar styraci¯ua L.) in a plantation. Three-year-old seedlings derived from four half-sib seed sources from alluvial and upland sources were fertilized with N and P and monitored over a 9-year period. Sweetgum did not respond to P, but showed a 14% diameter growth response to N. Bottomland hardwood sites in the Upper Coastal Plain physiography of north-central Louisiana are typically found along smaller streams, sometimes referred to as `upland bottoms,' in contrast to the large alluvial plains associated with the Mississippi and other major rivers (Adams, 1983). Soils of these upland alluvial areas re¯ect the geochemistry of the surrounding uplands which are generally acidic and low in natural fertility. The purpose of this study was to examine the diameter growth response to N and P fertilization of commercial hardwood species in natural stands on these minor stream alluvial sites. 2. Study area and methods The study area was located in Lincoln Parish, approximately 8 km east of Ruston, Louisiana (328N latitude, 928W longitude). Soils of the study site were Guyton silt loam (®ne-silty, siliceous, thermic Typic Glossaqualf), which are widely mapped in the region on such landscapes. The site was occupied by a mixed stand of bottomland hardwood species of between 30 and 40 years of age and about 23.7 m2 haÿ1 of basal area. Overstory species consisted of water oak (Quercus nigra L.), cherrybark oak
(Q. pagodaefolia Ell.), white oak (Q. alba L.), post oak (Q. stellata Wangenh), and sweetgum (Liquidambar styraci¯ua L.). Midstory and understory species included bluebeech (Carpinus caroliniana Walt.), ironwood (Ostrya virginiana Mill.) and red maple (Acer rubrum L.). A second-order perennial stream ran through the site and caused infrequent, short duration ¯ooding mainly during the winter and spring. Beyond the alluvial ¯oodplain, the area was characterized by hilly uplands supporting mixed pine-hardwood forests on soils chie¯y of the Ultisol order. Four treatments were used in the study. These treatments were control (no application of fertilizer), N applied singly at a rate of 168 kg haÿ1 as ammonium nitrate, P applied singly at the rate of 56 kg haÿ1 as triple super phosphate, and N and P applied together at the aforementioned respective rates. The rates of application were derived from recommendations for upland pine fertilization in the region (Wells and Allen, 1985). Fertilizer application was made with a hand spreader in March 1994. The treatments were applied to three repetitions of 0.1 ha square plots for a total of 12 plots on the study site. A circular measurement plot of 0.04 ha was located within each treatment plot. A minimum distance of 15 m was kept between treatment plots to maintain plot integrity. All trees greater than 10 cm at breast height in the measurement plots were measured for dbh. Initial measurements were made prior to initiation of growth in March 1994. Remeasurements were made at the end of the growing seasons in 1994 and 1995. Diameter increment data for all species combined was analyzed by year and as combined 2 year cumulative data using ANOVA at the 0.05 level. Because diameter growth on the midstory and understory species was so small, only the commercial overstory species (Quercus species and sweetgum) were included in the statistical analyses. Tree species were also grouped into three categories, red oaks, white oaks, and sweetgum and the data was reanalyzed. Mean separations were made using Duncan's multiple range test also at the 0.05 level. 3. Results and discussion Due to the small sample size and relatively high variability, only the combined species 2-year
M.A. Dunn et al. / Forest Ecology and Management 114 (1999) 261±264 Table 1 Diameter increment over two growing seasons for hardwoods on treatment plots Control
Treatment Diameter increment cma
Species groups
Nitrogen
Phosphorus
NP
All commercial Year 1 Year 2 Total
species 0.37a 0.12a 0.49a
0.46a 0.23a 0.69ab
0.42a 0.20a 0.62ab
0.54a 0.29a 0.83b
Red oaks Year 1 Year 2 Total
0.45a 0.16a 0.60a
0.53a 0.30a 0.83a
0.76a 0.40a 1.16a
0.64a 0.37a 1.02a
White oaks Year 1 Year 2 Total
0.17a 0.08a 0.25a
0.17a 0.00a 0.17a
0.44a 0.25a 0.69a
0.44a 0.29a 0.73a
Sweetgum Year 1 Year 2 Total
0.29a 0.03a 0.32a
0.51a 0.30a 0.80a
0.20a 0.03a 0.23a
0.34a 0.00a 0.34a
a
Values in a row followed by the same letter are not significantly different at the 0.05 level.
cumulative diameter increment on the NP treatment was signi®cantly different (70% greater) from the control at the 0.05 level (Table 1). Large, although not statistically signi®cant differences in some of
263
the other mean values indicate some important trends that should be noted. For all commercial species combined, the N treatment resulted in a 41% increase in 2-year diameter increment, while the P treatment produced only a 27% increase over the control (Fig. 1). This is consistent with ®ndings of fertilization studies in Southern pine forests of the region, where NP fertilization typically yield greater growth gains than either nutrient alone (Wells and Allen, 1985). When considering only red oak species over two growing seasons, N alone increased diameter increment by 38%, P alone by 93%, and NP by 70% (Fig. 2). White oaks over two growing seasons actually showed a small decrease in mean diameter increment compared to the control with N alone, but an increase of 176% with P alone and a 192% increase with NP (Fig. 2). Sweetgum showed a greater response to N alone with a 150% increase in 2-year diameter increment over the control, while there was a negative response to P alone and only a 7% response to NP (Fig. 2). These results suggest that the oaks, especially the white oaks, respond better to P fertilization and that sweetgum responds better to N fertilization. Nelson and Switzer (1990) also found that sweetgum in plantations responded only to N fertilization. However, due to the limitations of this study and the lack of statistical signi®cance we can only speculate on the ®ndings.
Fig. 1. Diameter increment of commercial hardwood species over 2 years following fertilizer treatment applications.
264
M.A. Dunn et al. / Forest Ecology and Management 114 (1999) 261±264
Fig. 2. Two-year diameter increment of species groups by fertilizer treatment.
Second year (1995) diameter growth was generally less than that of year 1 (1994) in all treatments (Fig. 1). The reason for this is unclear. Precipitation amounts and distribution were similar during the two growing seasons (April to October). Remeasurement of the plots in year 3 (1996) might have been revealing. Unfortunately, storm damage and a subsequent salvage harvest operation destroyed several of the study plots during that growing season.
The study indicates that further study of fertilization in natural bottomland hardwood sites on minor stream bottoms in the Upper Coastal Plain is justi®ed. In addition, the study suggests that different species in these mixed hardwood forests may respond differently to fertilizer applications and this should be evaluated in further work.
4. Conclusion
Adams, J.C., 1983. Water oak regeneration in the South's upland bottomland. USDA, Forest Service General Technical Report SE-24, pp. 177±179. Miegroet, H., Norby, R.J., Tschaplinski, T.J., 1994. Nitrogen fertilization strategies in a short-rotation sycamore plantation. Forest Ecology and Management 64, 13±24. Nelson, L.E., Switzer, G.L., 1990. Sweetgum half-sib seed source response to nitrogen and phosphorus fertilization in Mississippi. Soil Science Society of America Journal 54, 871±878. Wells, C.G., Allen, H.L., 1985. When and where to apply fertilizer: A loblolly pine management guide, USDA Forest Service General Technical Report SE-36. Williams, R.A., Farrish, K.W., 1994. Effects of fertilizer and herbicide application on the growth and yield of older loblolly pine plantations ± two year results. In: Edwards, M.B. (Ed.), Proceedings of the Eighth Biennial Southern Silvicultural Research Conference, USDA Forest Service General Technical Report SRS-1.
This paper presents 2-year diameter growth responses to N and P fertilization of a bottomland hardwood stand on a minor stream bottom in northern Louisiana. Two-year cumulative diameter increment was signi®cantly increased by 70% with the NP fertilizer treatment. However, due to inadequate sample size and high variability, only speculative trends could be observed in the remaining relationships. These trends seem to indicate that the oaks, especially the white oaks, responded to P fertilization, while sweetgum responded to N. Both of the oak groups seemed to respond to the NP treatment, while sweetgum did not show a similar response for that treatment. Diameter growth was generally lower across all treatments in the second growing season. The reasons for this decline are unclear.
References
Fertilization response in a natural bottomland hardwood stand in north-central Louisiana Michael A. Dunn1,a,*, Kenneth W. Farrishb, John C. Adamsc b
a LSU Agricultural Center, Louisiana Cooperative Extension Service, P.O. Box 25100, Baton Rouge, LA 7894-5100, USA Arthur Temple College of Forestry, Stephen F. Austin State University, P.O. Box 6109 SFA Station, Nacogdoches, TX 75962-6109, USA c Professor of Forest Genetics and Silviculture, School of Forestry, Louisiana Technical University, Ruston, LA 71272, USA
Abstract The effect of nitrogen and phosphorus fertilization on growth of a natural bottomland hardwood stand in north-central Louisiana was evaluated. A typical mixed stand of pole-sized and small saw-timber bottomland hardwoods with about 23.7 m2 haÿ1 of basal area was used in the study. Soils were Guyton silt loam (Fine-silty, siliceous, thermic Typic Glossaqualf). Three fertilizer treatments plus a control were replicated three times on 0.1 ha plots. The treatments consisted of nitrogen (168 kg haÿ1) as ammonium nitrate, phosphorus (56 kg haÿ1) as triple super phosphate, and NP. Trees greater than 10 cm at dbh were measured for diameter before fertilization and remeasured after one and two growing seasons. Diameter increment served as the response variable. Results showed a statistically signi®cant (p<0.05) increase (70 pct greater than the control) in diameter growth for the 2 year total increment on the NP treatment with all species combined. While the small sample size and relatively high amount of variability resulted in no further statistical signi®cance among the treatments, the data did reveal trends that need further investigation. Sweetgum (Liquidambar styraci¯ua L.) responded to N alone, while the oaks (Quercus), especially the white oaks, responded to P alone. The oaks also responded to NP, while no similar response was seen from sweetgum for that treatment. # 1999 Elsevier Science B.V. All rights reserved. Keywords: Fertilization; Hardwoods; Sweetgum; Liquidambar styraci¯ua; Red oaks; White oaks; Quercus
1. Introduction To keep pace with increasing demands for its products, the forest products industry continues to seek new ways to increase wood and ®ber production from forests. In northern Louisiana, new capacity in the oriented strand board industry coupled with increased demand for speci®c qualities of paper in *Corresponding author. 1 Formerly Research Assistant, School of Forestry, Auburn University, Auburn, AL, USA.
the paper products industry have lead to an overall increase in demand for hardwood ®ber. This has resulted in interest in increasing productivity of hardwood forests in the region. From March 1994 to November 1996, a study was conducted in north-central Louisiana to determine the effect of nitrogen and phosphorus fertilization on growth of bottomland hardwood species in natural stands. A previous study in the region had shown that from 25- to 30-year-old loblolly pine (Pinus taeda L.) plantations responded well to nitrogen and phosphorus fertilization on upland sites (Williams and Farrish,
0378-1127/99/$ ± see front matter # 1999 Elsevier Science B.V. All rights reserved. PII: S0378-1127(98)00357-0
262
M.A. Dunn et al. / Forest Ecology and Management 114 (1999) 261±264
1994). However, very little research has been conducted into the possible growth response from fertilization of naturally established bottomland hardwood stands on minor stream bottoms in the region. In fact, very little research regarding hardwood fertilization has been conducted in the southern United States, especially on natural stands. Miegroet et al. (1994) evaluated the effect of various N (urea) fertilizer regimes on an American sycamore (Plantanus occidentalis L.) plantation. Their ®ndings indicated that a treatment in which N was applied in increasing amounts as trees accumulated biomass was optimum in increasing stem biomass production and reducing potential groundwater contamination. Nelson and Switzer (1990) performed ®eld research into the response of sweetgum (Liquidambar styraci¯ua L.) in a plantation. Three-year-old seedlings derived from four half-sib seed sources from alluvial and upland sources were fertilized with N and P and monitored over a 9-year period. Sweetgum did not respond to P, but showed a 14% diameter growth response to N. Bottomland hardwood sites in the Upper Coastal Plain physiography of north-central Louisiana are typically found along smaller streams, sometimes referred to as `upland bottoms,' in contrast to the large alluvial plains associated with the Mississippi and other major rivers (Adams, 1983). Soils of these upland alluvial areas re¯ect the geochemistry of the surrounding uplands which are generally acidic and low in natural fertility. The purpose of this study was to examine the diameter growth response to N and P fertilization of commercial hardwood species in natural stands on these minor stream alluvial sites. 2. Study area and methods The study area was located in Lincoln Parish, approximately 8 km east of Ruston, Louisiana (328N latitude, 928W longitude). Soils of the study site were Guyton silt loam (®ne-silty, siliceous, thermic Typic Glossaqualf), which are widely mapped in the region on such landscapes. The site was occupied by a mixed stand of bottomland hardwood species of between 30 and 40 years of age and about 23.7 m2 haÿ1 of basal area. Overstory species consisted of water oak (Quercus nigra L.), cherrybark oak
(Q. pagodaefolia Ell.), white oak (Q. alba L.), post oak (Q. stellata Wangenh), and sweetgum (Liquidambar styraci¯ua L.). Midstory and understory species included bluebeech (Carpinus caroliniana Walt.), ironwood (Ostrya virginiana Mill.) and red maple (Acer rubrum L.). A second-order perennial stream ran through the site and caused infrequent, short duration ¯ooding mainly during the winter and spring. Beyond the alluvial ¯oodplain, the area was characterized by hilly uplands supporting mixed pine-hardwood forests on soils chie¯y of the Ultisol order. Four treatments were used in the study. These treatments were control (no application of fertilizer), N applied singly at a rate of 168 kg haÿ1 as ammonium nitrate, P applied singly at the rate of 56 kg haÿ1 as triple super phosphate, and N and P applied together at the aforementioned respective rates. The rates of application were derived from recommendations for upland pine fertilization in the region (Wells and Allen, 1985). Fertilizer application was made with a hand spreader in March 1994. The treatments were applied to three repetitions of 0.1 ha square plots for a total of 12 plots on the study site. A circular measurement plot of 0.04 ha was located within each treatment plot. A minimum distance of 15 m was kept between treatment plots to maintain plot integrity. All trees greater than 10 cm at breast height in the measurement plots were measured for dbh. Initial measurements were made prior to initiation of growth in March 1994. Remeasurements were made at the end of the growing seasons in 1994 and 1995. Diameter increment data for all species combined was analyzed by year and as combined 2 year cumulative data using ANOVA at the 0.05 level. Because diameter growth on the midstory and understory species was so small, only the commercial overstory species (Quercus species and sweetgum) were included in the statistical analyses. Tree species were also grouped into three categories, red oaks, white oaks, and sweetgum and the data was reanalyzed. Mean separations were made using Duncan's multiple range test also at the 0.05 level. 3. Results and discussion Due to the small sample size and relatively high variability, only the combined species 2-year
M.A. Dunn et al. / Forest Ecology and Management 114 (1999) 261±264 Table 1 Diameter increment over two growing seasons for hardwoods on treatment plots Control
Treatment Diameter increment cma
Species groups
Nitrogen
Phosphorus
NP
All commercial Year 1 Year 2 Total
species 0.37a 0.12a 0.49a
0.46a 0.23a 0.69ab
0.42a 0.20a 0.62ab
0.54a 0.29a 0.83b
Red oaks Year 1 Year 2 Total
0.45a 0.16a 0.60a
0.53a 0.30a 0.83a
0.76a 0.40a 1.16a
0.64a 0.37a 1.02a
White oaks Year 1 Year 2 Total
0.17a 0.08a 0.25a
0.17a 0.00a 0.17a
0.44a 0.25a 0.69a
0.44a 0.29a 0.73a
Sweetgum Year 1 Year 2 Total
0.29a 0.03a 0.32a
0.51a 0.30a 0.80a
0.20a 0.03a 0.23a
0.34a 0.00a 0.34a
a
Values in a row followed by the same letter are not significantly different at the 0.05 level.
cumulative diameter increment on the NP treatment was signi®cantly different (70% greater) from the control at the 0.05 level (Table 1). Large, although not statistically signi®cant differences in some of
263
the other mean values indicate some important trends that should be noted. For all commercial species combined, the N treatment resulted in a 41% increase in 2-year diameter increment, while the P treatment produced only a 27% increase over the control (Fig. 1). This is consistent with ®ndings of fertilization studies in Southern pine forests of the region, where NP fertilization typically yield greater growth gains than either nutrient alone (Wells and Allen, 1985). When considering only red oak species over two growing seasons, N alone increased diameter increment by 38%, P alone by 93%, and NP by 70% (Fig. 2). White oaks over two growing seasons actually showed a small decrease in mean diameter increment compared to the control with N alone, but an increase of 176% with P alone and a 192% increase with NP (Fig. 2). Sweetgum showed a greater response to N alone with a 150% increase in 2-year diameter increment over the control, while there was a negative response to P alone and only a 7% response to NP (Fig. 2). These results suggest that the oaks, especially the white oaks, respond better to P fertilization and that sweetgum responds better to N fertilization. Nelson and Switzer (1990) also found that sweetgum in plantations responded only to N fertilization. However, due to the limitations of this study and the lack of statistical signi®cance we can only speculate on the ®ndings.
Fig. 1. Diameter increment of commercial hardwood species over 2 years following fertilizer treatment applications.
264
M.A. Dunn et al. / Forest Ecology and Management 114 (1999) 261±264
Fig. 2. Two-year diameter increment of species groups by fertilizer treatment.
Second year (1995) diameter growth was generally less than that of year 1 (1994) in all treatments (Fig. 1). The reason for this is unclear. Precipitation amounts and distribution were similar during the two growing seasons (April to October). Remeasurement of the plots in year 3 (1996) might have been revealing. Unfortunately, storm damage and a subsequent salvage harvest operation destroyed several of the study plots during that growing season.
The study indicates that further study of fertilization in natural bottomland hardwood sites on minor stream bottoms in the Upper Coastal Plain is justi®ed. In addition, the study suggests that different species in these mixed hardwood forests may respond differently to fertilizer applications and this should be evaluated in further work.
4. Conclusion
Adams, J.C., 1983. Water oak regeneration in the South's upland bottomland. USDA, Forest Service General Technical Report SE-24, pp. 177±179. Miegroet, H., Norby, R.J., Tschaplinski, T.J., 1994. Nitrogen fertilization strategies in a short-rotation sycamore plantation. Forest Ecology and Management 64, 13±24. Nelson, L.E., Switzer, G.L., 1990. Sweetgum half-sib seed source response to nitrogen and phosphorus fertilization in Mississippi. Soil Science Society of America Journal 54, 871±878. Wells, C.G., Allen, H.L., 1985. When and where to apply fertilizer: A loblolly pine management guide, USDA Forest Service General Technical Report SE-36. Williams, R.A., Farrish, K.W., 1994. Effects of fertilizer and herbicide application on the growth and yield of older loblolly pine plantations ± two year results. In: Edwards, M.B. (Ed.), Proceedings of the Eighth Biennial Southern Silvicultural Research Conference, USDA Forest Service General Technical Report SRS-1.
This paper presents 2-year diameter growth responses to N and P fertilization of a bottomland hardwood stand on a minor stream bottom in northern Louisiana. Two-year cumulative diameter increment was signi®cantly increased by 70% with the NP fertilizer treatment. However, due to inadequate sample size and high variability, only speculative trends could be observed in the remaining relationships. These trends seem to indicate that the oaks, especially the white oaks, responded to P fertilization, while sweetgum responded to N. Both of the oak groups seemed to respond to the NP treatment, while sweetgum did not show a similar response for that treatment. Diameter growth was generally lower across all treatments in the second growing season. The reasons for this decline are unclear.
References