|Pezeshki, S. R.|
|Shields Jr, Fletcher|
Submitted to: Trees: Structure and Function
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/5/2008
Publication Date: 5/27/2008
Citation: Carpenter, L.T., Pezeshki, S., Shields Jr, F.D. 2008. Responses of non-structural carbohydrates to shoot removal and soil moisture treatments in Salix nigra. Trees: Structure and Function 22: 737-748, Doi 10.1007/s00468-008-0234-7. Interpretive Summary: Erosion of stream banks and adjacent floodplains causes land loss, water quality degradation and habitat damage in many agricultural watersheds, and planting willow cuttings is a widespread component of bank erosion control and riparian zone restoration strategies. However, success rates for such plantings are often disappointing, and causes are not well understood. The effects of shoot removal from recently planted cuttings (similar to the effects of grazing by animals or abrasion by floods) was studied in a greenhouse setting for plants growing under three moisture regimes (flooded, ideal and drought) and three levels of shoot removal (none, partial and all shoots removed). The levels of stress on the plants were gaged by measuring the amount of nonstructural carbohydrate in the plant tissues. The results showed that willow cuttings may experience lower levels of survival when subjected to shoot removal and moisture stresses simultaneously, particularly when drought and severe shoot removal occur.
Technical Abstract: Above-ground disturbances are common in dynamic riparian environments, and Salix nigra is well-adapted with a vigorous resprouting response. Soil moisture stresses are also common, and S. nigra is flood tolerant and drought sensitive. Nonstructural carbohydrate (NSC) reserves provide energy for regeneration of shoot tissue until new functional leaves are developed. NSC reserves in S. nigra following shoot removal were quantified for three soil moisture regimes: well-watered (W), periodic flooding (F) and drought (D); and three shoot removal treatments; no shoots removed (R0), partial shoot removal (R1), and complete shoot removal (R2). Plants were harvested when new shoot development was observed (Day 13). Both roots and cuttings were important NSC reservoirs during resprouting, with decreases in root (31%) and cutting (14%) biomass in R2 compared to R0. Rapid recovery of photosynthetic surface area (from 15% to 37% of R0) was found in R1. A clear pattern of starch mobilization was found in roots in R0, R1 and R2, with lowest root starch concentration in W, F higher than W, and D higher than F. Shoot starch concentration was lower in F and D compared to W in R0; however, in R1, shoot starch was reduced in W compared to F and D, possibly indicating reduced rates of translocation during soil moisture stress. Total plant NSC pool was greater in F and D treatments compared to W, and progressively reduced from R0 to R1 to R2. Results indicated negative effects of drought, and to a lesser extent periodic flooding, on resprouting response, with implications for reduced survival when exposed to combined stresses of aboveground disturbance and soil moisture.