Soil, hydroperiod and bedding effects on restoring bottomland hardwoods on flood-prone agricultural lands in North Louisiana, USA
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07 cpg022 11/4/03 9:34 am Page 181
Soil, hydroperiod and bedding
effects on restoring bottomland
hardwoods on flood-prone
agricultural lands in North
Louisiana, USA
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WILLIAM B. PATTERSON* AND JOHN C. ADAMS
School of Forestry, Louisiana Tech University, Ruston, Louisiana, USA
* Corresponding author. E-mail: wpatter@lans.latech.edu
Summary
Many of the bottomland hardwood forests of the Lower Mississippi Alluvial Valley, USA have been
converted to agriculture, thus constituting a sizable loss in ecological and socio-economic functions.
Bottomland hardwood forest afforestation on marginal agricultural lands has grown considerably
since 1990. However, many failures in bottomland hardwood afforestation have occurred for
various reasons, including misunderstandings or ignoring the relationships between species, soil and
hydrology. In October 1996, a 32-ha tract on an abandoned agricultural field in Catahoula Parish,
Louisiana, USA was site prepared for afforestation by bedding (moulding soil in parallel ridges). The
following January it was planted with seedlings of Nuttall oak (Quercus nuttallii Palmer) and green
ash (Fraxinus pennsylvanica Marsh.), and direct seeded with Nuttall oak. The objective of this study
was to evaluate the effects of bedding (within three soil types) on species survival and growth. Soil
redox potential measurements indicated that the soils were intensely anaerobic during frequent
prolonged seasonal inundation and saturation events. Bedding clayey soils significantly increased
mean height of planted and direct-seeded Nuttall oak, but not that for green ash. Bedding appears to
be somewhat effective in restoring site microtopography, reducing soil hydroperiod and enhancing
planted Nuttall oak height growth on poorly drained, clayey soils.
Introduction servancy, 1992). A high percentage of these defor-
ested farmlands was marginal for agricultural
Over the last two centuries about three-quarters production due to soil and soil/water problems.
of the Lower Mississippi Alluvial Valley has In the past 20 years a sizable number of hectares
been deforested for agricultural production have been replanted to trees. Initial work with
(MacDonald et al., 1979; The Nature Con- afforestation resulted in many failures to obtain
© Institute of Chartered Foresters, 2003 Forestry, Vol. 76, No. 2, 200307 cpg022 11/4/03 9:34 am Page 182
182 F O R E S T RY
adequate regeneration. Many of these failures poorly drained and frequently flooded Alligator
were the result of poor species/site matches. series was 27.1 m, and on the clayey, poorly
Other failures resulted from a lack of under- drained Perry series, 24.7 m (Broadfoot, 1976).
standing of the modifications of the sites, and Average measured site index (50 year base age)
subsequent changes in the soil–water relation- for green ash on the Alligator series was 24.4 m,
ships, duration of inundation, and changes in and 21.0 m on the Perry series (Broadfoot, 1976).
flood patterns resulting from agricultural and Ozalp et al. (1998), in Mississippi, found Nuttall
other anthropic activities (Stanturf et al., 1998, oak fifth year survival, height and diameter un-
2001). Lockhart et al. (2003) argue that there is affected by soil series. Their soils included the
no single prescription for bottomland hardwood clayey Sharkey series (Chromic Epiaquert) and
regeneration that suits all potential afforestation loamier soils.
projects in this region. Bedding poorly drained The study site is part of a 4000-ha area that
soils should be investigated as a potential tech- was cleared of bottomland hardwoods about
nique for increasing afforestation success. 40 years ago and converted to cropland. The area
Bedding, or mounding soil in parallel ridges, is was land levelled and ditched, thus altering
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a common site-preparation practice for establish- natural drainage, and is located near the conflu-
ing conifer plantations on wet sites of the lower ence of the Ouachita and Boeuf Rivers, down-
coastal plain in the south-eastern United States. stream of a medium-sized metropolitan area
Bedding is also commonly applied on peaty soils (Monroe, LA). This study was designed to
in Ireland, Scotland, Scandinavia and Canada examine survival and growth of Nuttall oak and
(Paavilainen and Päivänen, 1995; Rothwell et al., green ash on bedded and non-bedded site prep-
1993). Bedding a lower coastal plain wetland in aration treatments applied to three soil series
South Carolina, USA lowered the overall surface impacted by altered hydrologic regimes.
water table for 2 years after stand establishment
(Xu et al., 2000, 2002). Bedding also increased
the depth of the water table and raised the soil
redox potential, an indicator of soil aeration, on Methods
a slash pine (Pinus elliottii Engelm. var. elliottii) Study site
plantation in central Louisiana (McKee and
Shoulders, 1970). Numerous studies have estab- The study site was a 32-ha area of abandoned
lished that bedding usually increases early cropland located on Bouef River Wildlife
loblolly pine (Pinus taeda L.) and slash pine Management Area, which is between the Bouef
growth on poorly drained sites (Langdon, 1962; and Ouachita Rivers in northern Catahoula
McKee and Shoulders, 1970; Mann and Parish, Louisiana (31º 56´ lat., 91º 52´ long.). The
McGilvray, 1974; McKee and Wilhite, 1986). area has an average annual precipitation of
One exception was on silty soils in Louisiana, 148.3 cm, an average annual daily temperature of
where bedding did not improve soil drainage 18.7ºC, an average annual daily maximum
(Haywood et al., 1990). Thus, it is possible that temperature of 25.1ºC and an average daily
the benefits of bedding bottomland soils will minimum temperature of 12ºC (Boyd, 1986).
differ according to inherent soil properties.
Bottomland hardwood species productivity has
Study establishment
been related to soil series and site conditions,
including hydrologic regime or hydroperiod. For The study site was bedded in October 1996, using
example, best site conditions for Nuttall oak a Savannah bedding plough pulled by a rubber-
(Quercus nuttallii Palmer) and green ash (Fraxi- tyred skidder, and was planted to bottomland
nus pennsylvanica Marsh.) include silty or loamy hardwoods in January 1997. Bare root seedlings
textures, winter to spring flooding, waterlogging of Nuttall oak and green ash were planted by
in winter only, water table at 0.6–1.8 m depth, hand on beds and non-bedded positions. Nuttall
and concave microsite positions (Baker and oak was also direct seeded by hand at 7–10 cm
Broadfoot, 1979). Average measured site index depth on both bedded and non-bedded areas.
(50 year base age) for Nuttall oak on the clayey, Herbicides were not applied due to prolonged07 cpg022 11/4/03 9:34 am Page 183
R E S T O R AT I O N O F B O T T O M L A N D H A R D W O O D S 183
high water. The experimental design was ran- A US Geological Survey river stage (measured
domized block, with blocking on the three soil and recorded by the US Army Corps of Engineers)
series mapped on the site. Alligator clay (very- is located ~12 km upstream on the Boeuf River.
fine, smectitic, thermic Chromic Dystraquert) Stage data for the period 1997–2001 were
occurs in the lowest elevation backswamps sub- evaluated and related to the restoration area’s
jected to frequent backwater flooding. Hebert silt elevation, to determine inundation frequency and
loam (fine-silty, mixed, active, thermic Aeric Epi- duration. Days with river stage heights at or
aqualf) is located on the natural levee, and Perry above the sites elevation were counted as inunda-
clay (very-fine, smectitic, thermic Chromic Epia- tion events, and these events at the lower end of
quert) is situated in intermediate positions. Bed predicted flooding were verified in the field. To
and non-bed rows were replicated randomly assess soil hydroperiod and onset of oxidizing
within each block (soil series). Seedlings were and reducing conditions, soil redox potential elec-
planted with a spacing of 3 m 3 m (1087 trees trodes were installed in November 1998 on beds
ha–1) on 3-m-wide rows. Nuttall oak acorns were and non-bedded sites in each of the three soils
direct-seeded at 0.5-m intervals on 3-m-wide mapped on the site. For each soil type, three plots
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rows. Survival on random 30 m 30 m plots were established in which five platinum wire
(four plots per a treatment) was measured at the redox electrodes, constructed as in Faulkner et al.
end of the fourth growing season. A plot of this (1989), were installed at 15 cm and 30 cm depths
size would allow for 10 planting spots per row for for both bedded and non-bedded positions.
seedlings or 32 sowing spots per row for direct-
seeded acorns. There were 10 rows in a plot.
Seedling height and ground-line diameter were
also measured at the end of the fourth growing
Results and discussion
season. Survival, height and diameter of planted During the 5-year period, the restoration area
Nuttall oak, direct-seeded Nuttall oak and was inundated by the Boeuf River, for at least two
planted green ash were analysed by bedding treat- flood events per year (Figure 1). The site was
ment within soil series using analysis of variance flooded up to 116 consecutive days in the winter
(ANOVA) of the General Linear Model Pro- and spring, and occasionally in the late fall, at
cedure of SAS (SAS Instititute, Inc., 1999). heights up to 3 m above the backswamp soil
18
17
Plots flooded
16
15
Stage (m)
14
13
12
11
10
9
8
1/ 7
1 7
/1 97
1/ 8
1 8
/1 98
1/ 9
1 9
/1 99
1/ 0
1 0
/1 00
1/ 1
1 1
/1 01
02
1/ 7
1/ 8
1/ 9
1/ 0
1/ 1
4/ 199
7/ 99
4/ 199
7/ 99
4/ 199
7/ 199
4/ 200
7/ 00
4/ 200
7/ 00
1/ 99
1/ 99
1/ 99
1/ 00
1/ 00
10 /19
10 /19
10 /19
10 /20
10 /20
20
1
1
2
2
/1
/1
/1
/2
/2
1/
1/
Date
Figure 1. Stage of Boeuf River at Fort Necessity, LA, USA, 12 km upstream from study area, for the period
1997–2001. The heavy horizontal line through the graph indicates the stage at which the study site is
inundated.07 cpg022 11/4/03 9:34 am Page 184
184 F O R E S T RY
Table 1: Flooding duration and height above flood stage at the study area from 1997 to 2001, Bouef River
Wildlife Management Area, LA, USA
Total days Consecutive flooding Maximum flood height
Year flooded periods (days) above flood stage (m)
1997 129 116, 13 2.41
1998 95 89, 6 1.67
1999 73 35, 15, 11, 4, 4, 4 2.39
2000 20 15, 3, 2 1.49
2001 110 53, 32, 15, 7, 3 3.13
(Alligator clay) level (Table 1). Soil oxidation- following up Miwa et al. (1993), found a fifth
potential (redox) measurements (Figure 2) indi- year 65 per cent survival for direct-seeded Nuttall
cate that these soils have mostly oxidized with oak on the clayey Sharkey soil series in Missis-
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aerobic conditions from mid-summer to Novem- sippi. In the study reported here, in Louisiana,
ber, and undergo periods of moderate reduction planted Nuttall oak seedlings on beds had a mean
and anaerobic conditions (redox potential ≤200 survival of 66.6 per cent compared with the 55.8
mV; Gambrell and Patrick, 1978; Patrick et al., per cent survival on non-bedded sites. On a
1996) before flooding, ponding and saturation similar poorly drained clay soil in Mississippi,
induces periods of intense reduction and anaer- Schweitzer et al. (1997) measured 63 per cent sur-
obic conditions (redox potential ≤100 mV; Gam- vival after one growing season. Ozalp et al. (1997)
brell and Patrick, 1978; Patrick et al., 1996) had 79 per cent fifth year survival for planted
lasting several months in the spring. The timing Nuttall oak on similar clay soils at Lake George,
of the flooding periods indicated in Figure 1, as Mississippi. For this study reported here, in
well as high seasonal precipitation relative to Louisiana, green ash survival was nearly identical
evaporation, is associated with the decline in soil on beds (60.0 per cent) or on non-bedded
redox depicted in Figure 2. Soil redox potential in positions (61.6 per cent). Krinard and Kennedy
the rooting zone was slightly higher on bedded (1987) reported 80 per cent survival for Nuttall
sites versus non-bedded sites for extended oak and 98 per cent survival of green ash at age
periods, indicating less intensely anaerobic con- 4 years on a plantation without weed control
ditions. and without prolonged inundation on a cleared,
clayey poorly drained Vertisol in Mississippi. The
two studies in the Lower Mississippi Alluvial
Survival
Valley were on soils very similar to the Alligator
Overall survival on bedded sites for all species and Perry in this study; however, the former sites
was 61 per cent, versus 47.3 per cent on non- were protected from prolonged flooding by levees.
bedded sites. Direct-seeded Nuttall oak survival
was very high regardless of bedding (95–100 per
Height and diameter growth
cent). Planted Nuttall oak seedlings had a 66.6
per cent survival rate on bedded positions, versus On the Alligator clay soils, planted and direct-
55.8 per cent survival on non-bedded sites. Green seeded Nuttall oak had significantly greater
ash seedling survival did not differ on bedding fourth year heights on beds than on non-bedded
position; survival on beds was 60.0 per cent com- positions (Table 2). On Perry clay soils, however,
pared with 61.6 per cent off beds. Measured sur- bedding significantly increased only planted
vival rates for direct-seeded Nuttall oak in this Nuttall oak height. There were no differences in
study are significantly higher than those of Miwa height of bedded or non-bedded Nuttall oaks on
et al. (1993) and Schweitzer et al. (1997) in the better drained and loamy Hebert silt loam,
Mississippi, but the latter two studies were first- whether trees were planted or direct seeded.
year measurements in which Nuttall oak may Bedding did not significantly increase green ash
have delayed germination. Ozalp et al. (1998), height on any of the three soils.07 cpg022 11/4/03 9:34 am Page 185
R E S T O R AT I O N O F B O T T O M L A N D H A R D W O O D S 185
(A)
400
350
300
pH 7 (mV)
250
200
150
100 Bedded
Non-bed
50
0
8 9 9 9 9 9 9 0 0 0 0 0 0
19
9 99 99 99 99 99 99 00 00 00 00 00 00
1/ 1 /1 1 /1 1/1 1/1 1 /1 1/1 1 /2 1 /2 1 /2 1 /2 1/2 1/2
1 2/ 2/ 4/ 6/ 8/ 1 0/ 1 2/ 2/ 4/ 6/ 8/ 1 0/ 1 2/
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Date
(B)
400
350
300
pH 7 (mV)
250
200
150
100 Bedded
50 Non-bed
0
8 9 9 9 9 9 9 0 0 0 0 0 0
99 99 99 99 99 99 99 00 00 00 00 200 200
1 /1 1/1 1 /1 1 /1 1 /1 1 /1 1 /1 1 /2 1 /2 1 /2 1 /2 1/ 1/
12/ 2/ 4/ 6/ 8/ 1 0/ 12/ 2/ 4/ 6/ 8/ 10
/
12
/
Date
Figure 2. Soil redox potential (adjusted to pH 7) for bedded and non-bedded positions on Alligator clay
soils in the study area, Bouef River Wildlife Management Area, LA, USA. (A) Soil redox potential at 15 cm
depth; (B) soil redox potential at 30 cm depth.
Nuttall oak height after 4 years in the Missis- On the more poorly drained Alligator and
sippi study on Sharkey clay was 90 cm on clay better drained Hebert soils, bedding did not affect
sites without weed control (Krinard and planted Nuttall oak mean diameter (Table 2).
Kennedy, 1987). Fifth year heights of Nuttall Bedding significantly increased direct-seeded
oak on Sharkey clay at Lake George, Missis- Nuttall oak diameters only on the Alligator soil.
sipppi averaged 177 cm (Ozalp et al., 1998). On the Perry soil, only planted Nuttall oak had
Those height measurements are much greater significantly greater mean diameter on beds com-
than that reported in this study in Louisiana, pared with that on non-bedded sites. Fifth year
which was unprotected by levees and subject to diameter of Nuttall oak on Sharkey soil at Lake
long and frequent inundation. Schweitzer et al. George, Mississippi was 27 mm (Ozalp et al.,
(1997) found Nuttall oak seedlings averaged 1998). Green ash did not have significant mean
40 cm tall after 1 year on a similar poorly diameter differences between bedded and non-
drained clay soil. bedded sites on any of the three soils. Krinard and07 cpg022 11/4/03 9:34 am Page 186
186 F O R E S T RY
Table 2: Fourth year heights and ground-line diameters of seedlings on bedded and non-bedded site positions
for three soils, Bouef River Wildlife Management Area, LA, USA in 2000
(A) Mean heights with standard errors for species planted or seeded on bedded and non-bedded site positions
are compared within each soil series
Mean height (cm)
Alligator clay Perry clay Hebert silt loam
Species Bedded Non-bedded Bedded Non-bedded Bedded Non-bedded
Nuttall oak, planted 57.6 ± 2.6* 43.7 ± 2.7* 86.5 ± 6.3* 36.8 ± 6.2* 83.3 ± 6.4 80.2 ± 5.4
Nuttall oak, direct seeded 36.8 ± 1.8** 23.8 ± 2.2** 45.2 ± 2.3 40.0 ± 4.9 46.6 ± 4.1 50.7 ± 5.1
Green ash, planted 29.1 ± 2.5 38.5 ± 13.1 38.8 ± 5.0 40.3 ± 3.5 35.4 ± 2.8 33.8 ± 2.0
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(B) Mean diameters with standard errors for species planted or seeded on bedded and non-bedded site positions
are compared within each soil series
Mean height (cm)
Alligator clay Perry clay Hebert silt loam
Species Bedded Non-bedded Bedded Non-bedded Bedded Non-bedded
Nuttall oak, planted 12.4 ± 0.8 14.5 ± 4.7 13.3 ± 1.0* 5.3 ± 1.5* 15.3 ± 1.2 15.1 ± 0.9
Nuttall oak, direct seeded 6.4 ± 0.4** 4.1 ± 0.3** 7.8 ± 0.5 7.0 ± 0.7 7.1 ± 0.7 6.2 ± 0.5
Green ash, planted 6.4 ± 0.8 9.0 ± 1.9 5.9 ± 0.7 6.9 ± 0.6 6.9 ± 0.5 7.5 ± 0.9
* P-value < 0.05, ** P-value < 0.01 (significance level attained in ANOVA). Comparisons are between bedded
and non-bedded positions within soil for each species/regeneration technique.
Kennedy (1987) measured green ash height of Although the growth results are not spectacular,
2.3 m at 4 years in Mississippi on clay soils mean fourth year height for a major desirable
without weed control. species (Nuttall oak) was increased by bedding
Bedding effects on Nuttall oak height and these low, clayey backswamp Vertisols. We con-
diameter were significant only on the poorly clude that bedding on the more poorly drained
drained Alligator and Perry clays, and not on the and clayey soils, such as Alligator clay, benefits
somewhat poorly drained Hebert silt loam. the height growth of planted Nuttall oak more
Similar results were found with loblolly pine than bedding on loamier somewhat poorly
heights and diameters on bedded south-eastern drained soils such as Hebert. Neither green ash
US soils (Mann and McGilvray, 1974; McKee and height nor diameter growth is benefited by
Wilhite, 1986), where bedding benefited pine bedding on any of these three soils. Bedding was,
growth on poorly drained soils, but not some- however, effective in increasing overall species
what poorly drained or moderately well-drained survival. Bedding helps restore soil and site
soils. micro-topography, and influences the local
hydrological regime, but the massive changes
made by humans are difficult to mediate and are
certainly a challenge for the land manager
Conclusions working in heavily impacted areas. Bedding
Frequent, high and prolonged flooding and long frequently flooded, poorly drained, clayey soil
periods of anaerobic conditions on this site make should be considered a potential practice to
bottomland hardwood restoration a challenge. benefit Nuttall oak seedling growth when07 cpg022 11/4/03 9:34 am Page 187
R E S T O R AT I O N O F B O T T O M L A N D H A R D W O O D S 187
planning forest restoration plantings on former US Department of the Interior, Fish and Wildlife
agricultural fields. Service, Washington, DC.
McKee, W.H. Jr. and Shoulders, E. 1970 Depth of water
table and redox potential of soil affect slash pine
Acknowledgements growth. For. Sci. 16, 399–402.
McKee, W.H. Jr and Wilhite, L.P. 1986 Loblolly pine
This study was funded in part by the Utility Forest
response to bedding and fertilization varies by
Carbon Management Program, Edison Electric Insti-
drainage class on Lower Atlantic Coastal Plain sites.
tute and the McIntire-Stennis Forestry Cooperative
South. J. Appl. For. 10, 16–21.
Research Program.
Mann, W.F. Jr and McGilvray, J.M. 1974 Response of
slash pine to bedding and phosphorus application in
southeastern flatwoods. USDA Forest Service
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