Hydroperiod Influences on Nutrient Dynamics in Decomposing Litter of a Floodplain Forest

Abstract

Lack of clarity regarding the relationship between hydroperiod and decomposition dynamics has long been a barrier to the development of a clear understanding of floodplain biogeochemistry. Relationships between hydroperiod and decomposition processes were investigated using a controlled, field approach on the Ogeechee River floodplain in south Georgia. The study intent was to develop cause‐effect relationships between specific flooding regimes and decomposition parameters. Microcosms designed to manipulate flooding regimes were installed and used in combination with litterbags containing abscised foliage. Treatments were designed to mimic realistic hydroperiod‐nutrient inflow scenarios and included: a nonflooded control, flooded for 6 mo, flooded for 3 mo, flooded intermittently for 4 mo, flooded for 3 mo with elevated P inflow, and flooded for 3 mo with elevated N inflow. Mass, C, N, and P dynamics were studied for a 106‐wk period. Flooding stimulated mass, C, N, and P loss. The data suggest that single, brief flooding regimes may stimulate mass and C loss to the greatest extent. The proportion of N and P remaining after 106 wk was only marginally different among flooding regimes. However, temporal patterns of immobilization‐mineralization were strongly influenced by the nature of the flooding regime.

Detrital Decomposition As a Measure of Ecosystem Function in Created Wetlands

“…For instance, van der Valk et al (1991) reported a greater CPOM decomposition rate in a variable flooding treatment than a more constant water level. Other studies confirmed the influence of water level variability on CPOM decomposition (Connor and Day 1991, Neckles and Neil1 1994, Lockaby et al 1996, Atkinson and Cairns 2001, a relationship that is linked to alternating periods of saturation and aerobic respiration (Brinson et al 1981). In our study, CPOM decomposition rates were strongly related to hydrologic regime, but decomposition rates in the 12-and 155-year-old wetlands were likely impeded by desiccation, as reported by Atkinson and Cairns (2001) and van der Valk et al (1991).…”

Influence of environmental parameters on litter decomposition in wetlands in West Virginia, USA

“…It also is possible that there was more FET than is ideal for decomposition. Lockaby et al (1996) found that a single, relatively brief inundation period had the greatest positive influence on decomposition rate. As conditions change from flooded to exposed or vice versa, invertebrate and microbial communities change and processing is interrupted (Barlocher et al 1978).…”

“…Litter was carefully removed from the interior of the bag and sediment was rinsed off. We oven-dried (65 C) leaf litter for about one week until a constant mass was reached (Morris & Lajtha 1986;Lockaby et al 1996), recorded mass, and ground the litter to a powder in a 2-mm mesh Wiley Mill (Thomas Scientific, http://www.thomassci.com). Three subsamples of the ground litter were then incinerated to calculate ash-free dry mass (AFDM).…”

Leaf Litter Decomposition and Nutrient Dynamics in Four Southern Forested Floodplain Communities

“…Rates are lower where permanently flooded, permanently dry, or even alternating aerobic and anaerobic conditions prevail. Lockaby et al (1996) suggested that brief flooding regimes, followed by moist but well aerated conditions, maximized mass and carbon (C) loss. Brinson (1981) also has suggested that, where decomposition is not limited by either oxygen availability or moisture, temperature is the "single most important variable" governing mass loss.…”