|Shields Jr, Fletcher|
Submitted to: Wetlands Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/2/2004
Publication Date: 12/1/2004
Citation: Li, S., Pezeshki, S.R., S. Goodwin, Shields, F.D., Jr. 2004. Physiological Responses of black willow (Salix nigra) cuttings to a range of soil moisture regimes. Photosynthetica 42(4):585-590. DOI: 10.1007/S11099-005-0017-y Interpretive Summary: Stream channel erosion results in degraded water quality, loss of land, and ecological damage, but it has been shown that willow trees rooted from cuttings are effective and economical plants for helping to stabilize eroding stream channels. Long-term success of willow plantings on channel banks is often disappointing, perhaps due to the wide range of soil moisture conditions there. A laboratory experiment was conducted to compare the rates of photosynthesis and other physiological processes for willow cuttings subjected to ideal, flooded and droughty soil conditions. Growth of shoots and roots were adversely affected by both drought and flooding, i.e. continuously flooded cuttings accumulated the lowest shoot biomass while the final height and root growth were most adversely affected by periodic drought. These findings emphasize the need to evaluate stream bank sites before planting willow cuttings, and, in particular, that greater success with bank restoration projects may be achieved if willow cuttings are planted in moist, but well-drained soils.
Technical Abstract: Black willow (Salix nigra) is used extensively for riverbank erosion control and riparian zone restoration. However, many projects in the southeastern U. S. have experienced low survival rates, particularly in zones where soil moisture conditions were extremely wet or dry. The mechanisms underlying the poor performance are less clear. This study was conducted to quantify the physiological responses of black willow to various soil moisture regimes. Potted cuttings were subjected to four levels of soil moisture conditions: no flooding (control), continuous flooding, periodic flooding and periodic drought. Continuously flooded cuttings accumulated the lowest shoot biomass while the final height and root growth were most adversely affected by periodic drought. Stomatal limitation was one of the factors that led to reduced photosynthetic capacity in continuously flooded cuttings. Under periodic drought conditions, stomatal closure, decreased leaf chlorophyll content and increased dark fluorescence yield contributed to photosynthetic decline.