Growth and resource allocation of whitetop ( Scolochloa festucacea) along a water depth gradient

Abstract

The above- and below-ground growth of the prairie marsh grass whitetop, Scolochloa festucacea (Willd.) Link, was studied along a gradient of water depth to investigate the importance of shifts in above- and below-ground biomass allocation in explaining observed patterns of above-ground biomass under different flooding regimes. In pot culture, above- and below-ground biomass values were similar between water depths of 15 cm below the soil surface (−15 cm), at the soil surface (0 cm) and 15 cm above the soil surface, but biomass declined with water depths greater than 15 cm. Whitetop allocated an increasing proporotion of total biomass to above-ground parts as water depths increased from −15 to 15 cm. In the field, above-ground biomass varied more in relation to changing water depths than below-ground biomass. Greater depth and duration of spring flooding increased both above- and below-ground biomass and relative biomass allocation to above-ground parts. The increase of total biomass that occurred with flooding was a more important influence on patterns of above-ground biomass than were shifts in relative biomass allocation.