Abstract Detail

Ecophysiology

Equiza, Maria Alejandra [1], Cirelli, Damian [2], Zwiazek, Janusz J. [3].

Salt spray differentially affects phenology and growth in four tree species.

The application of de-icing salts in roads and walkways during the winter season is considered a major factor in the decline of urban trees. Airborne salts (spray and dry dust) are among the most injurious pollutants affecting urban trees located in close proximity to high-traffic roads. The impact of salt spray on tree performance is difficult to evaluate due to the complexity of the urban environment, where the interactions of traffic characteristics, salt application practices and weather conditions result in highly variable salt spray loads. Hence, our current understanding on how salt spray affects trees is still poor. We have conducted experiments to assess the effect of salt spray on tree species commonly planted along roadsides in the City of Edmonton. We also investigated the possibility that significant amounts of salt can be taken through the bark of twigs and young stems. Dormant seedlings of American elm (Ulmus americana), green ash (Fraxinus pennsylvanica), chokecherry (Prunus virginiana) and white spruce (Picea glauca) were kept in cold frames during the winter season. Plants were sprayed either with water or with a solution of NaCl (90 g L^-1) two (2X NaCl) or five times (5X NaCl) through January-March. Plants were moved to a greenhouse during early March. Time of flushing, % of flushed buds, bud growth, plant height, stem diameter, and leaf dry weight were assessed. The effect of salt spray differed among tree species, and was dependent on the rate of application (2X or 5X NaCl). The overall trend included: delayed in bud break, top dieback, reduction in the number of flushed buds, and reduction in plant overall growth. Chokecherry was the species most negatively affected by the salt-spray treatments and the only one with plant mortality (41%) in the 5X NaCl. Salt uptake through the bark was investigated by several methods: application of fluorescent dyes as proxy for salt, mapping of Na⁺ distribution by energy dispersive X-ray analysis (SEM-EDX), and assessment of the electrical conductivity of stem segments after successive rinses in distilled water. Results suggest that the uptake of significant amounts of salt through the bark is possible and also species-dependent. We expect that developing a better understanding of the effects of salt-spray on the overall tree performance will aid in the improvement of tree planting strategies in urban environments.

1 - University of Alberta, Renewable Resources, 4-39 Earth Sciences Building, University of Alberta, Edmonton, Alberta, T6G 2E3, Canada
2 - University of Alberta, Renewable Resources, 4-40 Earth Sciences Building, University of Alberta, Edmonton, Alberta, T6G 2E3, Canada
3 - University of Alberta, Renewable Resources, 4-38 Earth Sciences Building, University of Alberta, Edmonton, Alberta, T6G 2E3, Canada

Keywords:
salt stress
salt spray.

Presentation Type: Poster:Posters for Topics
Session: P
Location: Hall D/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 5:30 PM
Number: PEP011
Abstract ID:1240
Candidate for Awards:None