resulting from natural catastrophes or man-induced 

 changes can affect these movement patterns. Man can 

 alter the upland forest habitat by indiscriminately 

 harvesting its resources (7). 



4.14.2 PRODUCERS 



The upland forest habitat includes pine and hard- 

 wood components. The major pine species are lob- 

 loUy, shortleaf, longleaf, and slash. These pines are 

 found in association with such hardwoods as water 

 oak, American elm, sweetgum, and southern magnolia. 

 Table 4.26 provides a more complete list of the major 

 hardwood species and other understory plants. 



The distribution of pine species in the upland 

 forest habitat is related to soil moisture. Longleaf 

 and shortleaf pines are found on dry ridges, while 

 loblolly occurs on moist sites. The latter becomes the 

 first dominant tree species in the succession of this 

 forest type. Young stands of loblolly pine can grow 

 0.6 to 0.9 m/yr (2 to 3 ft/yr), but generally attain 

 22.5 to 25.5 m (75 to 85 ft) over a period of 50 

 years (Walker 1962). 



Oak and hickory seedlings begin to dominate 20 

 to 30 years after pines become established (Barrett 

 and Downs 1943). During this stage in the forest suc- 

 cession, the shaded and undisturbed forest floor is a 

 poor seedbed for pines but not for hardwoods (Walker 

 1962, Wenger 1968). As older pines die from such 

 causes as wind and lightning damage, insect infesta- 

 tions, and diseases, openings in the canopy occur that 

 are not closed by adjacent pine crowns. Instead, the 

 small shade-tolerant hardwoods in the understory fill 



these vacancies. This process usually begins about 75 

 to 100 years after pine establishment and the replace- 

 ment of pines by hardwoods is complete within 200 

 to 300 years. The climax of this natural succession is 

 a forest of mixed hardwoods with no remaining pines. 

 However, both natural and human processes retard 

 development of this mixed hardwood forest. Fire is 

 frequent enough to set back succession to a pine- 

 dominant stage (called a fire disclimax), and the 

 practice of clearcutting is usually followed by replant- 

 ing with pine seedhngs. Hence,climax stands of mature 

 hardwoods are nonexistent in the Chenier Plain. 



Table 4.26. List of hardwood and understory species 

 in the loblolly pine-shortleaf pine type 

 forest (Parker et al. 1975). 



Common name 



Eastern red cedar 

 Water oak 

 Overcup oak 

 Burr oak 

 Willow oak 

 Swamp hickory 

 Southern hackberry 

 American elm 

 Sweetgum 

 Southern magnolia 

 Sycamore 

 Blackcherry 

 Texas sugarberry 

 Water locust 



Blackgum 



Tupelo 



Water ash 



American beauty berry 



Blackberry 



Palmetto 



Rough-leaf dogwood 



Boxelder 



Spanish moss 



Paspalum 



Scribner panicum 



Indiangrass 



Smutgrass 



Poison iv>- 



Ttmber harvest by man 



*■ Export to Ctienier Plain 



Figure 4-45. Conceptual model of energy flow and interrelationships between upland forest and aquatic habitats 

 in the Chenier Plain. 



220 



