Regeneration Of Cypress, Taxodium Distichum, And Taxodium Ascendens, In Logged And Burned Cypress Strands At Corksrew Swamp Sanctuary, Florida

Gunderson, Lance

Regeneration of two species of cypress, Taxodium distichum (L.) - Richard (baldcypress) and Taxodium ascendens Brogn. (pondcypress), was investigated in successional seres resulting from logging (1954) and burning (1963) of cypress strands at Corkscrew swamp Sanctuary, near Naples, Florida. The effects of a dike constructed in 1969 to impound water to the north were also examined. Sites were established in areas that were: 1) logged and north of the dike, 2) logged and south of the dike, 3) logged-and-burned and north of the dike, 4) logged-and-burned and south of the dike, and 5) burned and north of the dike. Seedlings of T. ascendens were transplanted in January, 1976 among existing vegetation and into cleared areas at each study site, and seedling heights were measured through October, 1976. Seeds of T. distichum and T. ascendens were sown at each study site. Germination of seed was monitored in the field and under greenhouse and laboratory conditions. Water levels were monitored at each site from October, 1975 through October, 1976. Vegetation maps were drawn from sequential sets of aerial photographs to determine rates of change of the vegetation after disturbances of logging and burning. There was no significant difference in the growth rates of cypress seedlings among the five sites. No detectable difference has measured between seedlings growing among existing vegetation and seedlings growing in cleared areas. Maximum mean height increase of seedlings measured vras 80%. Survival of transplanted seedlings was 66%. Maximum germination of sown cypress seeds was 4.8%. Average germination in the field was 2.1%; less than 5.% of those which germinated survived through the wet season. At the logged sites hard Hoods such as Ilex cassine, Acer rubrum, Persea palustris, Myrica cerifera, and Myrsine guianensis are present in the overstory and are actively regenerating. Some cypress regeneration by coppicing and seed is occurring at these sites also. The logged-and burned and burned sites are dominated by Salix caroliniana. There is no cypress regeneration at the logged-and-burned sites, but some regeneration is occurring by coppice and seed at the burned site. Measurements of water levels indicate longer periods of inundation at the logged and logged-and-burned sites than at the burned site. The dike creates lower water levels to the south, but does not change the period of inundation. Vegetation maps indicate that hardwoods persist following logging. Colonization by S. caroliniana follows destruction of the hardwoods by fire. Lack of seed sources, immobility of cypress seed, low viability, and crucial water requirements for germination seem to be retarding cypress regeneration. Once established, cypress is able to compete with existing vegetation.