Above: Taking a root core.

Below: Putting out membranes used to measure the availability of nitrogen and phosphorus in the soil.

Above: Removing soil from a core sampler.

Fine Root Dynamics in Forested Wetlands (Graduate Project)

Research Team: Matt Neatrour (Graduate Student), Dr. Stephen W. Golladay (Associate Scientist) and Robert Jones (Virginia Tech)

We examined the effects of ecosystem and fine scale fertility on fine root biomass in three types of seasonally-inundated forested wetlands: floodplain swamps, river swamp sloughs, and depressional swamps. Floodplain swamps and river swamp sloughs are alluvial ecosystems and receive nutrient subsidies from streams during flood pulses. Depressional wetlands, in contrast, are hydrologically isolated from streams and receive most of their nutrients via precipitation. All wetlands used in this study were mature forests. We predicted that soil nutrient availability would reflect the amount of nutrient subsidies from streams (floodplain swamps > river swamp sloughs > depressional swamps) and that fine root biomass (< 2 mm diameter) would be inversely related to ecosystem fertility. In addition, we predicted that fine scale fertility would be strongly correlated with fine root biomass in depressional swamps. Preliminary data indicate that soil phosphorus availability was not different among wetland types, although soil nitrogen availability was greater in floodplain swamps than in depressional swamps. Fine root biomass did not differ between floodplain swamps (220 g/m2) and depressional swamps (504 g/m2). However, river swamp sloughs (647 g/m2) had greater root biomass than floodplain swamps. Fine scale fertility was generally not strongly correlated with fine root biomass within the sites. These data suggest that other factors, such as wetland hydrology, may be more important determinants of the differences in fine root biomass than ecosystem fertility. Studies are currently in progress to examine the interrelationship among wetland hydrology, soil nutrient availability, and fine root dynamics in these wetland types.

Additional Information:

This is ongoing Dissertation Research by M. Neatrour (1/2003) in the Biology Department of Virginia Tech University.

Craft, C.B. and W.P. Casey. 2000. Sediment and nutrient accumulation in floodplain and depressional freshwater wetlands of Georgia, USA. Wetlands 20: 323-332.

Funded by: The Joseph W. Jones Ecological Research Center and Virginia Tech