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Selection, Production and Establishment of Wetland Trees and Shrubs |
Prepared by M. P. Garber, Extension Horticulture, and D. J. Moorhead, Extension Forest Resources
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Selection, Production and Establishment of Wetland Trees and Shrubs |
Contents
Selecting Wetland
Plants
Sources of Plant Materials
Culture of Trees and Shrubs
Production Procedures for Liners
Purchasing Criteria for Liners
Establishment in the Field
Protection and restoration of wetlands has become a major initiative of state and federal governments. Wetland regulations in Section 404 of the Clean Water Act of 1987 touch the lives of people in agriculture and commercial and residential development and affect municipalities when wetlands are developed or changed.
Wetlands are landscapes influenced by water-saturated soils. Swamps, marshes and bogs are easily recognized as wetlands. Other important wetlands are found next to rivers and streams. Wetlands enhance ecological diversity, flood control, soil conservation, water quality, wildlife habitat, timber production and recreation.
In Georgia, 5.3 million acres of wetlands remain of the 6.8 million acres found at the time of European settlement. Each year more than 7,000 acres of wetlands are altered by development.
As the importance of maintaining functional wetlands becomes more apparent, attempts are being made to restore wetlands that have been altered. Landowners also are creating additional wetland areas on their property for recreation and aesthetics. Interest in the use of water and enhancement of wet areas in the landscape has increased rapidly in recent years. This ranges from pond gardening (creation of small ponds or water gardens) to enhancement of natural or man-made streams in the commercial landscape.
This publication is intended to assist those who: 1) restore wetlands; 2) establish new wetlands; 3) landscape low, wet areas in home yards or commercial developments; and 4) produce seedlings of wetland plants for commercial use or sale.
Selection of the proper plants is an important step to achieve the benefits of wetlands. Generally, wetland sites are technically defined by the presence of three characteristics:
Hydric soil development is influenced by water saturation or flooding. Wetland hydrology requires water saturation or flooding during some portion of the growing season. Hydrophytic vegetation includes plants, growing in water or soils and substrates that are periodically lacking in oxygen because of excessive water.
Plants can be divided into four groups which relate to their occurrence in wetland habitats:
Table 1 provides a selected list of wetland shrubs and trees native to Georgia that are suitable for creating or restoring wetlands. Because some native plants may not be available from nurseries, data on seed dispersal and seed treatment are included. Use this information to collect desired species from local seed sources.
A comprehensive listing of plants, from forbs and grasses to shrubs and trees, in wetlands and upland sites in Georgia is also available from the UGA Extension Service. It is called "Wetland Plants for Georgia" (Coder, 1990).
After selecting plant varieties, determine the necessary plant size, type (container-grown or bareroot) and whether specific cultivars are desired.
Plant Size
The size you need depends on how long you can wait for results. If you need trees above the "weeds" in one or two years, then select larger plants.
Liners or bareroot seedlings are the least expensive and smallest (1 to 2 feet tall). Whips are larger single-stemmed plants generally 4 to 6 feet tall with a ground-line stem caliper greater than ½ to 1¼ inches. Finished trees are 4 to 15 feet tall with well-branched crowns and are 2 to 4 inches in caliper.
Container vs. Bareroot Plants
With plants of equal size, those in containers are more expensive than bareroot plants due to growing costs. If price is your primary consideration, bareroot plants can be used. Bareroot plants generally are available only for limited periods during the year. In Georgia, they can be used from November through February.
For best results, bareroot plants should be lifted (removed from production beds) and planted while dormant. The planting season for bareroot plants can be extended by storing recently lifted trees at about 40F. Plants that are lifted at the wrong time or stored too long will not survive or grow well. It is best to use non-stored, recently lifted dormant trees. Because seedling roots can be broken during lifting, leaving fewer roots to take up water and nutrients, bareroot plants don't tolerate extremely wet or dry planting conditions.
Container plants can be used any month when soil moisture is adequate. They are the preferred choice from late spring to early fall. Purchase evergreen shrubs as container-grown plants to avoid leaf fall. Handle deciduous shrubs as bareroot trees.
Clonal vs. Seedlings
The choice of seedling or clonal (vegetatively propagated) material depends on the project objectives. To maintain the genetic diversity of the immediate area, seedlings produced from seed collected in the area are ideal. However, it is often difficult to find enough viable seed or to obtain plants in a timely manner. Another option is to collect seed from more distant areas. However, this may not be consistent with the project's objectives. When seed is not available, cuttings may be an option to propagate material from local plant sources. Also, genetic diversity of the vegetation can be maintained through use of several cultivars of each tree or shrub.
Another problem or opportunity with using seedlings is variation. For instance, oaks hybridize naturally. Since oaks are wind pollinated, there can be great variation in seedlings from a given tree from year to year. More than 100 different oak hybrids have been documented in the United States and Canada. Recent work at the University of Georgia has shown that willow oak -- an FACW species -- can be rooted successfully. Vegetative propagation procedures are needed to make clones of outstanding specimen plants for production and introduction into the commercial trade.
Tree liners, seedlings that have been grown from seed in a nursery bed for one year, can be purchased as vegetatively propagated plants. Examples are plants grown from cuttings, grafted plants, and plants produced in tissue culture. There is great interest in plants grown on their own roots for vegetative cuttings. Certain grafted cultivars of red maple (FAC) have a bud union incompatibility problem that results in stem breakage at the bud union. This problem may be genetic but can be overcome by rooting cuttings rather than grafting.
Another problem associated with rooted cuttings is overwinter survival. This has been documented in the following genera found in wetlands: Acer, Betula Cornus and Magnolia. Budbreak prior to overwintering, stored carbohydrate levels, and photoperiod all affect the survival of rooted cuttings that have been overwintered.
Several species of trees suited to wet sites are now available as tissue-cultured liners. Examples include several species of Betula and several selections of red maple. Advantages of tissue culture plants include increased vigor and uniformity and the ability to propagate otherwise difficult-to-root species.
If you choose to purchase plants for a wetland project, you must understand how they're produced to be an informed buyer. To control the cost of wetland revegetation, it is important to match site characteristics, the time frame for vegetative establishment (to obtain the finished look), and tree size and stock type (container or bareroot). Here is a brief overview of production procedures and available stock type.
Trees
There are four stages in production of bareroot deciduous trees (Figure 1).
Commercial tree production in Georgia has focused on the final stage - finished trees of 2 inches or greater caliper (ground-line diameter). For most wetland work, this size is larger than necessary.
Whips are not currently produced in Georgia but are available from Tennessee, Oregon and other states. The shade tree industry in Georgia would benefit greatly from local production of high quality whips. As with whips, most liners are purchased out of state (Florida and Tennessee). There are no inherent factors preventing Georgia growers from producing good quality liners and whips.
Starter material is the material used to begin new trees. These can be either vegetatively or sexually propagated trees. Vegetative propagation includes cuttings, tissue culture, and grafted material. Sexually propagated material is produced from seed. If you are growing liners or will purchase them from other nurseries, you should know the origin of the starter material. This will affect how the tree grows. It also is important to know if seed is from a local or distant source.
The term liner refers to the first stage of plant growth. If it is a seed propagated plant, liner refers to the first year of growth in the seed bed. In forestry, this is a 1-0 seedling, grown from seed in the nursery bed for one year without transplanting. Most liners of shade and ornamental trees are sold as 1-0 bareroot trees. Liners produced in the United States generally are grown in the ground, lifted during the winter and transplanted or sold the next spring.
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Figure
1. In-Ground Tree Production
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Liner also refers to container seedlings started from seed, cuttings, or tissue culture plantlets and grown for one growing season.
The 1-0 and container liners are used as starter material for whip production. Many catalogs refer to the liner stage as seedlings and in some cases will then have the notation of 1-0, 2-0 or 1-1. Seedlings grown for one year and then transplanted and grown another year are called 1-1 seedlings. The 2-0 and 1-1 seedlings are more common for slower growing conifer species.Whips are the next stage of plant production. The starter material for a whip is the 1-0 or container liner. The liner is placed in the ground in the spring and allowed to grow for one season.
If the plant is produced as a seedling, it is cut back to the ground at the beginning of the second year. Of the subsequent shoots that emerge, a superior shoot is selected and allowed to grow for one year. This plant is referred to as a one-year whip indicating one year of growth after cut-back but two years of growth after transplant. If the whip is a budded plant variety, budding occurs in the fall of the first year. The plant is cut just above the bud the next spring. The shoot that emerges from the grafted bud is grown for one year.
The term whip comes from the fact that after the second year you have a tall straight stem with few branches.
The third stage is the finished tree production. The starter material typically is a whip 1 to 5 inches in caliper. The bareroot whip is transplanted in the spring and grown for 3 to 5 years. How long it's grown depends on the variety and the caliper of tree demanded by the market. The material is typically handled as a ball-and-burlap plant.
Remember these qualities desired at each stage of production:
Be sure when you buy bareroot liners or whips that the goal of each stage has been met.
In recent years, more container-grown trees have been available. Container trees allow you to plant year-round and can be easier to handle on the job site. In most cases, trees grown in #5, #7 or #10 containers (5, 7 and 10 gallons respectively) are ideal size. Before you buy, be sure the root system has developed enough to have an intact soil ball. You should be able to pull out the tree by pulling on the base of the trunk and find the roots and planting media intact. If it falls apart, you may be planting a bareroot tree after normal handling.
Container trees are available from Georgia ornamental nurseries.
Shrubs
Most of the shrubs for Georgia wetlands are deciduous; that is, they lose their leaves in the fall. They are available in containers year-round from nurseries in Georgia and surrounding states.
Shrubs generally are sold by the size of the container, although some catalogs estimate plant height and diameter. The most common sizes are liners in 2¼-inch or 4-inch pots and #1 and #5 containers. The #1 containers offer sufficient size plants at a reasonable price. For harsh sites or extensive vegetation competition, the #5 containers may be better.
Liners are attractive where large numbers plants are required, weed competition can be controlled, and time to establishment is not critical.
A quality liner is the critical first step in the establishment of quality in-ground wetland trees and shrubs. Unfortunately, few people give enough attention to the quality of liners produced or purchased. But quality is perhaps the most important production variable. The information below will help liner customers assess the quality of liners and ask relevant questions to suppliers.
The first step in liner production is selection of the production site. The soil should be loose and well aerated at all times. Well aerated soil is critical to good root development, the primary objective of liner production. Therefore, the higher the sand content the better.
In the past, heavy soils have been used for hardwood production because many hardwood species grow in poorly drained soils with a high clay content. However, it is important to distinguish between what a plant will tolerate versus what it needs to produce a quality root system. Typical bottomland soils don't favor good root development. Aerated soils are important for hardwood seedlings and for conifer seedlings such as loblolly and slash pine.
The ideal site allows surface water run-off and percolation of rainwater and irrigation. It does not have a shallow hard pan that hinders root growth.
Seed bed preparation affects germination and the uniformity of seedling emergence. The seed bed generally is fumigated prior to planting to kill weed seed and pathogens.
There is a tradeoff between getting rid of all weed seed and pathogens and having some mycorrhizae present for hardwood seedlings. Mycorrhizae are naturally occurring beneficial fungi that enhance uptake of water and nutrients by the roots. However, fumigants such as methyl bromide can decrease the level of some species of mycorrhizae in the nursery bed. The higher the soil moisture content during fumigation the more complete will be the kill of mycorrhizae. Some types of mycorrhizae can be supplied as spores and as vegetative mycelium into the nursery bed at planting.
The equipment to form seed beds is readily available. The soil should be thoroughly pulverized and elevated seed beds established. One advantage of elevated seed beds is ease of root pruning. It is virtually impossible to do a good job of root pruning or wrenching if the seed bed is not elevated. Also, the elevated bed provides a well aerated medium for roots to grow.
You can get seedlings to emerge uniformly if all the seeds germinate at the same time. To help this happen, sort and grade the seeds before sowing. The more commonly used grading technique is flotation sorting to remove empty or damaged seeds. Table 1 tells whether all seed should be stratified to insure rapid, uniform germination.
Uniform seedlings also require uniform spacing and depth of sowing. Sowing machines are available for coniferous seed and are under development for hardwood seed. Each nursery must adapt existing seed sowers to get good results. Seed generally is sown in rows on 4- or 6-foot wide beds. Unlike broadcast seeding, row seeding allows lateral root pruning during production. Additionally, by controlling the number of seed in the rows, each seedling gets the most growing space possible.
The time of sowing also affects uniformity. With oak seed, many nurseries sow the acorns in the fall or wait until spring. But fall sowing can create problems. The seed is subjected to more variation in seedling emergence. The primary reason for fall sowing is convenience. However, nurseries can get excellent germination, even with storage-sensitive seed of the white oak group, if they store the seed at the proper moisture level and sow in the spring.
Once the seedlings have emerged, several cultural practices are necessary to control height growth, root system development and ground-line diameter to produce uniform seedlings.
The first step is to undercut the root system. Undercutting is done using a sharp narrow blade to cut horizontally beneath the bed, severing seedling taproots. If this is done soon after seedling emergence, multiple taproots will develop. That's important since the objective of the liner stage is root system development. This is especially true for taproot plants such as oaks. In fact, some nurseries pregerminate seed and then clip a portion of the radical (emerging root tip) prior to sowing. However, this is not necessary and costs more than early undercutting. Done properly, undercutting won't disturb the seedlings or severely hinder early growth.
Undercutting can be repeated two or three times during the growing season. Increase the depth of cutting by about 2 inches for each successive cut. In this way, you are continually pruning the tips of new roots. Avoid seedling damage by undercutting only when the plants are not in an active height growth stage. The presence of a well-developed terminal bud marks the end of active height growth.
Water management can be used to control seedling height and caliper. By withholding water in late summer and early fall you can slow top growth and favor caliper and root development. However, be careful to avoid severe water stress which causes leaf damage or leaf drop. This technique requires more research to measure the relationship between plant water status and subsequent growth.
The fertilization of hardwood seedlings also requires further study. In general, we start with the incorporation of a well balanced preplant fertilizer. This is complimented with liquid fertilizer once the plants are growing. The addition of micronutrients has given positive results in plant color and growth.
Wrenching is an effective method to control seedling height. It's done by running a thick bar underneath the root system at a slight angle. This lifts the seedlings, loosening the soil around the roots. Wrenching breaks the contact between the soil and root tips, resulting in a complete root pruning. The aeration and root pruning increase water stress and slow top growth. This creates more root tips, increases caliper and slows top growth.
Wrenching is a good, but seldom used, technique for controlling height that should be practiced by more nurseries. There is no set frequency for wrenching.
Top pruning in the nursery bed can increase the uniformity and caliper of conifer and hardwood seedlings. But this technique is risky and usually not recommended. When single stems are desired, top pruning hardwoods is not advised. Many pine species readily develop one dominant shoot after top pruning. However, with hardwoods top pruning usually results in two or three shoots. If seedlings are used as understock for grafting, it is not as critical since the tops will be cut off after one year. Top pruning may delay bud set in the fall, which delays the optimum time for lifting.
Another concern with top pruning is that it allows weak, low-vigor seedlings to catch up with the high-vigor seedlings. These low-vigor seedlings may show up as smaller cull plants in the next stage.
Uniform seedlings can be achieved by means other than top pruning: seed bed preparation, proper seed treatment, precision sowing, undercutting and wrenching, water management and fertilizers.
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Figure
2. Optimum Loblolly Pine Seedling
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Use these characteristics when buying deciduous wetland plants:
Desired characteristics for conifer seedlings, such as pine illustrated in Figure 2.
When wetlands are restored, a primary objective is often to re-create the "natural" hydrology of the site before alteration. Generally, ditches and other drainage structures are closed allowing water to cover the site.
In constructing artificial wetlands, a basin is excavated after removing and stockpiling topsoil. Following final grading and contouring of the excavated basin, the topsoil is replaced.
As the hydrologic function returns and stabilizes, distinct zones may develop on the site that affect vegetation. Because of drainage or soil conditions some sites within the wetland are best suited to a particular plant species. Attempts to establish unsuitable plants are futile and expensive.
Remember that newly planted tree seedlings and shrubs may not survive the hydrology that mature plants can and may be lost soon after planting. It may be necessary to restrict or delay the flooding of wetland areas for a year or so to allow the plants to become established.
Use Table 2 to determine seedling response to flooding. Note that some species tolerate some levels of flooding during the growing season while others can withstand only dormant season flooding. Species intolerant to growing season flooding should not be planted on sites prone to spring flooding unless water control structures are present to allow rapid removal of flood waters.
To match vegetation to the wetland, the hydrology of the site must be evaluated. Contour maps that show levels of inundation and soil saturation during the growing season are useful in planning revegetation. By comparing hydrology, soils and native plants of functionally similar adjacent wetlands, distinct zones can be identified. Then adapted species or mixes of normally occurring species can be selected. For example, cherrybark oak can be planted along better drained terraces while swamp tupelo can be planted on the poorly drained flats.
When an area does not have distinct zones that are particularly well suited for a given species, a mix of species can be planted across the entire site. This may be the practical approach on newly constructed wetlands that have been graded or leveled to remove major drainage patterns. Species that are adapted to a particular site will survive, while the others die off.
On all sites as the hydrology stabilizes, adapted species become established and native plants move in. On urban sites, native wetland grasses and forbs may be introduced to complete the landscape when the trees and shrubs are established.
Planting density depends on the goals and scope of the project. Urban wetlands may feature specimen plants representing the desired landscape. In large reconstructed or new wetlands, more plants may be desired. Hardwood plantations generally are established at 10 x 10-foot to 20 x 20-foot spacings. This represents 435 trees per acre at a 10 x 10 spacing and 108 trees per acre at a 20 x 20 spacing.
The importance of selecting healthy, vigorous planting stock suited to specific site conditions cannot be overemphasized. It's a waste of time and money to try to establish poor quality, unsuited plants.
1 Adapted from Coder, 1990; Teskey & Hinkley, 1977, USDA, 1974; Dirr 1983;
2 OBL- obligate; FACW- facultative wetlands; FAC- facultative; FACU- facultative upland. Indicators may be modified by (+) or (-) suffix; (+) indicates a species more frequently found in wetlands; (-) indicates species less frequently found in wetlands.
3 Flood Tolerance Mature Plants:
- VT- Very Tolerant-survives flooding for periods of two or more growing seasons.
- T-Tolerant-Survives flooding for one growing season.
- IT-Intermediately Tolerant- survives one to three months of flooding during the growing season.
- WT- Weakly Tolerant-survives several days to several weeks of growing season flooding.
- I-Intolerant-cannot survive even short periods of a few days or weeks of growing season flooding.
- NE-Not established.
4 Approximate dates across natural range of a given species.
5 Cold stratification -- place moist seeds in polyethylene plastic bags and place in refrigerated storage at 330-410 F for specified time.
Warm stratification -- place moist seeds in polyethylene plastic bags at 680-860 F for specified time.
Scarification -- mechanical or chemical treatment to increase permeability of seed coat.
Table 2. Seedling response of selected species to flooding conditions.1
| Species | Water Level | Seedling Survival2 | Comments |
| Boxelder
Acer negundo |
Total submersion growing season | 100% at
2 weeks 70% at 3 weeks 36% at 4 weeks (123) 0% at 32 days (5) |
Chlorotic leaves after 4 days. Slow recovery. (15) |
| Red
Maple Acer rubrum
|
Partial submersion growing season | 100% at
5 days 90% at 10 days 0% at 20 days |
Adventitious roots developed after 15 days (7) Height growth decreased
in saturated soil (7) |
| Soil saturation growing season | Growing season 100% at 32 days (12) | ||
| Silver
Maple Acer saccharinum |
Total submersion growing season | 100% at 3 weeks (12) | Lower
leaves wilt after 2 days. Slow recovery (5)
Height growth better at saturated conditions than field capacity (7) |
| Soil saturation growing season | 100% at 60 days (7) | ||
| River
Birch Betula nigra |
Soil saturation growing season | 100% at 32 days (13) | Growth severely stunted (13) |
| Pecan
Carya illinoensis |
Total submersion growing season | 75% at 4 weeks (12) | |
| Sugarberry
Celtis laevigata |
Soil saturation growing season | 100% at 60 days (7) | |
| Common
Buttonbush Cephalantus occidentalis |
Total submersion growing season | 100% at 30 days (6) | |
| Green
Ash Fraxinus pennsylvanica |
Total submersion growing season | 100% at
5 days 90% at 10 days 73% at 20 days 20% at 30 days (6) |
Lower
leaves chlorotic after 8 days (5)
Better growth in saturated soil than at field capacity (7) |
| Partial submersion growing season | 100% at 14 days (5) | ||
| Soil saturation growing season | 100% at 60 days (7) | ||
| Sweetgum
Liquidambar styraciflua |
Total submersion growing season | 0% at 32 days (5) | |
| Partial submersion growing season | 0% at 3 months (6) | ||
| Yellow
Poplar Liriodendron tulipifera |
Partial submersion growing season | 0% at
2 months (9) No adverse effects (12) |
|
| Water
Tupelo Nyssa aquatica |
Partial submersion growing season | 90%-100%
over growing season 32% when seedlings nearly overtopped (9) |
Best growth when water table fluctuates (4) |
| Swamp
Tupelo Nyssa sylvatica var. biflora |
Partial submersion growing season | 90-100% over growing season (4) | Poor
root growth in stagnant water (3,4)
Best growth in saturated soil (4) |
| Soil saturation growing season | 90-100% over growing season (4) | ||
| Slash
Pine Pinus elliottii |
Partial submersion growing season | 68% at
2 months 12% at 7 months (15) |
Root and shoot growth decreased (14) |
| Loblolly
Pine Pinus taeda |
|
Root and
shoot growth reduced during flooding (8) Dormant season flooding increased height and diameter growth (2) |
|
| American
Sycamore Platanus occidentalis |
Total submersion growing season | 100% at
10 days 0% at 30 days (6) |
Growth decreased by saturated soil (13) |
| Soil saturation growing season | 95% at 32 days (7) | ||
| Eastern
Cottonwood Populus deltoides |
Total submersion growing season | 0% at 16 days (5) | Best
growth when water table is 2 feet below surface (1)
High mortality when deeply flooded (5) |
| Partial submersion growing season | 90% at
10 days 70% at 20 days 47% at 30 days (6,7) |
||
| Cherrybark
Oak Quercus pagoda |
Total submersion growing season | 87% at
5 days 6% at 10 days 0% at 20 days (6) |
Height growth decreased by soil saturation (7) |
| Soil saturation growing season | 89% at
15 days 47% at 39 days 13% at 60 days (7) |
||
| Water
Oak Quercus nigra |
Partial submersion growing season | Survived 2 months (10) |
|
| Willow
Oak Quercus phellos |
Soil saturation growing season | 100% at 50 days (7) | Poorer growth in saturated soil than at field capacity (7) |
| Shumard
Oak Quercus shumardii |
Total submersion growing season | 100% at
5 days 90% at 10 days 6% at 20 days (6) |
Height growth poorer in saturated soil than at field capacity (7) |
| Soil saturation growing season | 100% at
30 days 66% at 60 days (7) |
||
| Black
Willow Salix nigra |
Total submersion growing season | 100% at 30 days (5,10) | Better height growth in saturated soil than at field capacity (7) |
| Soil saturation growing season | 100% at 60 days (7) | ||
| Baldcypress
Taxodium distichum var. distichum |
Total submersion growing season | 100% at 4 weeks (11) | |
| American
Elm Ulmus Americana |
Total submersion growing season | 100%
at 10 days 27% at 20 days 0% at 30 days (6) |
Height growth decreased in saturated soil (7) |
| Soil saturation growing season | 100% at
15 days 94% at 60 days (7,13) |
1Adapted from Teskey & Hinckley, 1977
2Seedling survival in relation to length of flooding.
3References:
- Broadfoot, 1973 6. Hosner, 1960 11. Loucks and Keene, 1973
- Burton, 1972 7. Hosner and Boyce, 1962 12. Larsen, 1963
- Harms, 1973 8. Hunt, 1950 13. McDermott, 1954
- Hook et al., 1970 9. Kennedy, 1970 14. McMinn and McNabb, 1971
- Hosner, 1958 10. Kennedy and Kinard, 1974 15. Walker, Green and Daniels, 1961
References
Broadfoot, W. M. 1973. Raised water tables affect southern hardwood growth. USDA Forest Serv. Res. Note SO-168.
Burton, J. D. 1972. Prolonged flooding inhibits growth of loblolly pine seedlings. USDA Forest Serv. Res. Note SO-124.
Coder, K. D. 1990. Wetland plants of Georgia. Univ. of Georgia Cooperative Extension Serv. Misc. Publ. 41 1. (Contact county Extension office for copy.)
Dirr, M. A. 1983. Manual of woody landscape plants. Third Edition. Stipes Publishing Co. Champaign, IL.
Federal Interagency Committee for Wetland Delineation. 1989. Federal manual for identifying and delineating jurisdictional wetlands. U.S. Army Corps of Engineers, U.S. Environmental Protection Agency, U.S. Fish and Wildlife Service, and USDA Soil Conservation Service, Washington, D.C. Cooperative technical publication. 76 p.
Harms, W. R. 1973. Some effects of soil type and water regime on growth of tupelo seedlings. Ecology 54(1):188-193.
Haynes, R. J., J. A. Allen, and E. C. Pendleton. 1988. Reestablishment of bottomland hardwood forests on disturbed sites: An annotated bibliography. U. S. Fish and Wildlife Serv. Biol. Rep. 88(42). 104 p.
Hook, D. D., C. L. Brown, and P. P. Kormanik. 1970. Lenticel and water root development of swamp tupelo under various flooding conditions. Bot. Gaz. 131:217-224.
Hortmann, H. T. and D. E. Kester. 1975. Plant propagation: Principles and Practices. Third Edition Prentice-Hall Inc., Englewood Cliffs, NJ.
Hosner, J. F. 1958. The effects of complete inundation upon seedlings of six bottomland tree species. Ecology. 39(2):371-373.
Hosner, J. F. 1960. Relative tolerance to complete inundation of 14 bottomland tree species. For. Sci. 6(3)246-251.
Hosner, J. F. and S. G. Boyce. 1962. Tolerance to water saturated soils of various bottomland hardwoods. For. SCI 8(2):180-186.
Kennedy, H. E. 1970. Growth of newly planted water tupelo seedlings after flooding and siltation. For. SCI 16:250-256.
Kennedy, H. E. and R. M. Krinard. 1974. 1973 Mississippi River flood's impact on natural hardwood forests and plantations. USDA Forest. Serv. Res. Note SO-177.
Lantz, C. W. (coord.) 1985. Southern pine nursery handbook. USDA Forest Serv. Southern Region.
Larsen, H. S. 1963. Effects of soaking in water on acorn germination of four southern red oaks. For. Sci. 9(2)236-241.
Loucks, W. L. and R. A. Keene. 1973. Submersion tolerance of selected seedling trees. J. For. 71:496-497.
McDermott, R. E. 1954. Effects of saturated soil on seedling growth of some bottomland hardwood species. Ecology. 35:36-41.
McMinn, J. W. and W. H. McNabb. 1971. Early growth and development of slash pine under drought and flooding. USDA Forest Serv. Res. Paper SE-89.
Simkins, H., K. D. Coder and G. Lewis. 1991. Wetlands heritage of Georgia. Univ. of Georgia Cooperative Extension Serv. Special Bull. 29. 19 p. (Contact county Extension office for copy.)
Teskey, R. O. and T. M. Hinckley. 1977. Impact of water level changes on woody riparian and wetland communities Vol. 11: The southern forest region. Fish and Wildlife Serv. USDI. FWS/OBS-77/59. 46 p.
USDA Forest Service. 1974. Seeds of woody plants in the United States. Agric. Handbook No. 450. 883 p.
Williams, R. D. and S. H. Hanks. 1976. Hardwood nurseryman's guide. USDA Handbook 473. 78 p.
An Equal Opportunity Employer/Affirmative Action Organization Committed to a Diverse Work Force
Bulletin 1082, Reprinted July 1999
Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, The University of Georgia College of Agricultural and Environmental Sciences and the U.S. Department of Agriculture cooperating.
