| Relations among wetland invertebrate abundance, litter decomposition and nutrient dynamics were studied from 1982-1985 in the Upper Mississippi Alluvial Valley. The purpose of this research was to document the influence of different forest types (pin oak-sweetgum and overcup oak-red maple) and flooding regimes (naturally flooded and managed) on nutrient cycling in bottomland hardwood wetlands and relate changes in energy and nutrient dynamics to wetland invertebrate abundance. Litter production, nutrient inputs, litter weight loss and nutrient dynamics, litter accumulation, soil chemistry and wetland invertebrate density were measured on 16 plots (four replicates in each forest type and flooding regime).; Overcup oak-red maple forest types, which were flooded into the growing season and at depths averaging 20-40 cm, had greater litterfall nutrient inputs, greater litter accumulation, higher soil and litter nutrients and less acid soils than the pin oak-sweetgum sites which were flooded less frequently and at shallower depths (5-15 cm). Naturally flooded sites had faster litter decay rates and less litter accumulation, but similar litter nutrient input and soil nutrient content to greentree reservoir sites, which are seasonally managed impoundments.; Forest type and flooding regime exert strong influences on certain measures (e.g. litter decomposition) and weaker influences on others (e.g. throughfall nutrient input was similar on all plots), while for some, like wetland invertebrate abundance, the influence was more complex. Pin oak-sweetgum forest types and greentree reservoirs had greater invertebrate abundance in fall, while in spring overcup oak-red maple and naturally flooded sites had greater invertebrate abundance. Invertebrates responded within days of nutrient and water inputs and were represented primarily by shredders and collectors.; The results of this study indicate that bottomland hardwoods are dynamic systems where flooding, decomposition and nutrient cycling were important ecological processes. These processes differed between forest types within bottomland wetlands. Furthermore, alterations in the natural, fluctuating flooding regime may adversely affect some of these processes. |
