| Biogeochemical comparisons were made between the Satilla River (SAT), a coastal plain blackwater river system, and the Altamaha River (ALT), a redwater river system of the Georgia Coastal Plain.; Litterfall production within the SAT and ALT sites averaged 5,316 and 5,666 kg ha-1 yr-1, respectively. Across both years, total aboveground net primary production (ANPP) for the SAT and ALT sites averaged 8,896 and 10,846 kg ha-1. Levels of nitrogen (N) and phosphorus (P) returned via litterfall for the SAT site averaged 39.8 and 4.0 kg ha-1 yr-1 , respectively, while the ALT site averaged 37 and 8.0 kg ha -1 yr-1, respectively. The litterfall N/P ratios for the SAT site (9.7) were greater than those of the ALT site (6.01), indicating slight P and N deficiencies within the SAT and ALT sites, respectively. Nutrient resorption proficiencies indicate that the SAT species are highly proficient at resorbing both N and P, while the ALT species were only highly proficient at resorbing N.; Decomposition rates were slightly faster within the SAT microsites. After 525 days in the field, percent of the original mass remaining in mixed species litterbags ranged from 36 to 59% for both the SAT and ALT sites. Both sites showed strong N mineralization and P immobilization patterns at 525 days.; In terms of a growth response, seedlings of the SAT soil showed a response to all three fertilization regimes; however, seedlings of the N+P and P fertilization regimes showed the significantly greater seedling height growth compared to the unfertilized control. It appears that P, and not N, is most limiting NPP on the SAT soil.; Nutrient use efficiency (NUE) indices indicated that the ALT microsites were slightly more efficient with N. By contrast, the SAT microsites were more efficient at cycling P. It appears that the differences in ANPP within these systems are also related to amounts of Ca in litterfall, more so than the amounts of N and P in litterfall.; In terms of N and P cycling, it is evident that the SAT site is more conservative with P cycling compared to N. By contrast, the ALT site appears to be slightly more conservative with N, and less conservative with P. (Abstract shortened by UMI.)... |
