water for one or more months of the growing season. 

 Functionally, swamp forests are similar to marshes, 

 although the woody vegetation in swamps gives it an 

 added dimension of diversity and function not found 

 in other wetlands. In the Chenier Plain region, the 

 swamp forest habitat is not very common, occur- 

 ring only among the upper floodplain regions of 

 major streams (fig. 4-23). Two types of wetland 

 forest are included in this habitat definition. One, the 

 baldcypress-water tupelo forest, is the true swamp 

 forest which tends to be flooded during most of the 

 year. The other type is the alluvial forest which is 

 flooded seasonally when river discharge is high. It 

 grades from stands of baldcypress and tupelo to 

 bottomland hardwood, and it is often characterized 

 by rapidly growing pioneer species such as the black 

 willow. 



4.6.1 PRODUCERS 



In the swamp forest system, there are several cate- 

 gories of plants, including trees, vines, and herbs. 

 True swamp forests, in addition to baldcypress and 

 tupelo, contain Drummond red maple, pumpkin ash, 

 and a number of woody shrubs, such as Virginia willow 

 and buttonbush. In the sliglitly drier areas, a more 

 diverse community of swamp maple, tupelo, boxelder, 

 Cottonwood, and black willow is found. Along the 

 natural levees of streams, sweet gum, overcup oak, 

 bitter pecan, persimmon, hackberry, and cherrybark 

 oak grow. The more common species of the swamp 

 and bottomland hardwood forests are listed in Table 

 4.14. This information covers southeastern Louisiana, 

 since no studies are available from the Chenier Plain. 

 A more complete Listing of trees, shrubs, vines, and 

 herbs characteristic of the swamp forest habitat 

 is given in appendix 6.3. 



Table 4.14. 



Tree species found in swamp forests 

 and bottomland hardwood forests in 

 southeastern Louisiana (Conner and 

 Day 1976). 



Common name 



Drummond red maple 



Tupelo 



Boxelder 



Swamp Cottonwood 



Baldcypress 



Rough-leaf dogwood 



Black willow 



American elm 



Shagbark hickory 



Pumpkin ash 



Water oak 



Hackberry 



Persimmon 



Deciduous holly 

 Bitternut hickory 

 Shumard red oak 

 Sweetgum 

 Swamp privet 

 Nuttall oak 

 Swamp red bay 

 Mock orange 

 Laurel oak 

 Elderberry 

 Buttonbush 

 Carolina ash 



The most abundant forms of nonwoody vegeta- 

 tion in the swamp forest are climbing vines. Poison 

 ivy, trumpet creeper, greenbriar, and peppervine are 

 only a few of the types found. 



Ferns and lichens are also common. Lichens are 

 important in the fixation of atmospheric nitrogen. 

 Herbs are not abundant on the swamp forest floor 

 because of the long periods of inundation and the 

 reduction of light by the forest canopy. In areas 

 where flooding is infrequent the understory is more 

 developed. 



Seasonal flooding, as compared to continuous in- 

 undation with standing water, provides optimum con- 

 ditions for tree growth and survival in the swamp 

 forest habitat (Conner and Day 1976). For instance, 

 in one greenliouse experiment, black-gum and tupelo 

 seedhngs grew better in tanks which had flowing water 

 than did seedlings in tanks with stagnant water (Harms 

 1973). In another investigation, Broadfoot and WiUis- 

 ton ( 1 973) reported that diameter growth of principal 

 tree species in a Mississippi swamp was 50 to 100% 

 greater in flood years. They also reported that im- 

 poundment of rainwater from December to June 

 increased hardwood diameter growth 25 to 90% de- 

 pending on the species. These examples amplify the 

 importance of the flooding requirement. 



Primary production is lower in the swamp forest 

 habitat than in marsh habitats, but in contrast to 

 other wetlands, organic matter is accumulated in tree 

 trunks and branches. Net primary productivity in a 

 baldcypress-tupelo forest and in a bottomland hard- 

 wood forest in southeastern Louisiana have been 

 calculated to be 1,140 and 1,574 g dry wt/m^/yr, re- 

 spectively (Conner and Day 1976). Of this, approxi- 

 mately one-half went into woody tissue. Some of 

 the leaves, twigs, and herbs are consumed directly, 

 but most fall onto the forest floor as organic litter, 

 which is consumed througli the detrital system 

 (fig. 4-24). 



Hurricanes have been a factor in the Louisiana 

 coastal systems for thousands of years. Strong winds 

 and heavy rains that are associated with hurricanes 

 can cause early defohation. Figure 4-24 shows an 

 early litterfall peak in September 1973 that resulted 

 from Hurricane Cannen (Day et al. 1977). A large 

 pulse of organic carbon, nitrogen, and phosphorus 

 was flushed downstream out of the swamp after the 

 hurricane. 



Timber Production. Cypress and tupelo logging 

 was the first forest industry in Louisiana and has been, 

 historically, the main reason for the high value put on 

 swamp forests. However, information on logging of 

 the virgin swamplands is virtually nonexistent (Nor- 

 gress 1947,Mancil 1972). As early as the 1700's, some 

 lumber was being shipped out of Louisiana, but it was 

 not until 1890 that the boom in lumbering began. 

 During the early phase of lumbering, logging was 

 restricted to the lands adjacent to waterways. In the 

 Chenier Plain, logs were floated down the Calcasieu 

 and Sabine rivers. Lake Chafles, in fact, became the 



184 



