Increased atmospheric carbon dioxide, a potential catalyst in the tree decline, mundulla yellows

• Published in: Journal of plant pathology 2008-11, Vol.90 (3), p.594-594
• Main Authors: Czerniakowski, B, Luck, JE
• Format: Article
• Language: English
• Subjects: Eucalyptus
• ISSN: 1125-4653

Mundulla Yellows (MY) is a progressive decline of Eucalyptus and other native species, caused by physiological iron deficiency and nutrient imbalance, induced by adverse soil conditions. MY affected trees are, in some cases, over 100 years old but in the last 30-40 years, soil environment under the affected trees has become adverse to tree health, causing decline in native trees that were previously well adjusted to the Australian environment. The exponential rise of CO sub(2) in the atmosphere that occurred in the 1960's-70's may be linked to the onset of MY and possibly other uncharacterized global tree declines. This theory appears to contradict many studies which have demonstrated that plants exposed to high CO sub(2) levels grow faster and are better able to cope with drought and salinity. However, the soil environment needs to be taken into consideration since it is well documented that elevated atmospheric CO sub(2) can directly and indirectly alter soil processes. Rising atmospheric CO sub(2) increases acids inputs to soil, soil mineral weathering processes and the level of dissolved organic carbon (DOC). Accelerated mineral weathering increases the level of dissolved inorganic carbonates in the soil solution that can be toxic to plants and can cause Fe deficiency and other nutrient imbalance. Increased level of DOC under elevated CO sub(2) can lead to toxicities and deficiencies of metals in plants because DOC affects the solubility and behaviour of metals in soil. The proposed influence of rising CO sub(2) on the Australian native tree decline, MY and its potential link with other uncharacterized tree declines will be presented.