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Ready-to-plant nursery stock of jack pine (Pinus banksiana Lamb.) and white spruce (Picea glauca (Moench) Voss) were subjected to simulated acid rains of pH 5.6 (control), 4.6, 3.6, and 2.6 under controlled growth room conditions to determine the threshold for damage. The two species exhibited contrasting response patterns to simulated acid rain treatments. Growth and chlorophyll content of jack pine were not adversely affected at any of the levels applied. Furthermore, no macroscopic foliar injury symptoms were evident and foliar nutrient levels remained unaffected. White spruce showed no statistically significant reduction in growth rate at any of the treatments. Needle chlorophyll a content of white spruce was not affected by any of the treatments, while chlorophyll b level was significantly reduced at pH 2.6. Symptoms of visible injury were observed to increase with rain acidity. No statistically significant change in the levels of foliar nutrients of white spruce were found, with the exception of the elevated S concentration at pH 2.6. 相似文献
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Nemr El Hajj Brice Mboumba-MamboundouRose-Marie Dheilly Zoheir AbouraMalek Benzeggagh Michèle Queneudec 《Industrial Crops and Products》2011,34(1):921-928
The aim of this paper is to develop a green composite using only flax fiber material for thermal insulations and sound absorbing using flax-tows and thus enhance the less noble part of the flax plant. The Lin-K process is a simple patented manufacturing process used to develop these self-linked materials. Thermal conductivity, absorbing acoustic coefficient, hydric properties and the effect of several parameters on these performances are reviewed. The use of fine flax-tows leads to extract more organic substances of the inner fibers during the microwave treatment which improves the mechanical performances and reduces the thermal conductivities of these materials. The environment has very significant effects on thermal stability and durability of these materials. 相似文献
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