Plants have an ideal relationship with the organisms of the planet. Plants use carbon dioxide released into the air and reciprocate with the release of oxygen. This process ensures the continual cycling of these gases in the environment. According to the U.S. Department of State, the primary source of man-made carbon dioxide is from fossil fuel combustion.
Function
Carbon dioxide is vital for plants to undergo photosynthesis, the process of making food. Sunlight provides the energy, and carbon dioxide and water provide the raw materials. The process yields sugar and energy for the plant, enabling it to grow. For people, plants reduce the amount of carbon dioxide in the atmosphere, the primary contributor to man-made greenhouse gases, according to the U.S. Department of State.
Changing Levels
Carbon dioxide levels vary seasonally. For example, in the spring, the levels of atmospheric carbon dioxide decline due to the large draw by plants, just beginning their growing season. Plants rely on carbon dioxide to fuel the growth process.
Plant Adaptations
Plants have evolved ways to still use carbon dioxide for photosynthesis even when conditions are too dry or too warm. Plants have pores called stomata on their leaves in order to capture carbon dioxide. However, if conditions are too dry, a plant may lose moisture too quickly. Rather than risk water loss, desert plants will keep their stomata closed during the warm daylight hours and open them at night in order to carry out gas exchange.
Environmental Effects
Environmental conditions can affect how a plant is able to get carbon dioxide. The effects of air pollution on plants are well-documented. A 1980 study published in the journal Cellular and Molecular Life Sciences found that air pollution reduces the size of plants' stomata. The effect is that growth will slow with inadequate carbon dioxide in order to make food. Yield is also affected by air pollution. A 2004 study in the journal Encyclopedia of Plant and Crop Science found that high levels of ground level ozone reduced crop yields in agricultural crops.
Water Efficiency
The mixture of gases in ground level ozone appears to be the reason for low crop yields. On the other hand, carbon dioxide enrichment on its own can help increase plants' water efficiency under certain environmental conditions. A 2008 study by the National Research Initiative and the USDA Cooperative State Research found that carbon dioxide enrichment can slow plants' use of water, especially during the cooler months. The finding is significant in that water savings can be a boon for drier areas of the country.
References
- U.S. Department of State: Greenhouse Gas Inventory
- "Ecology and Field Biology"; Robert Leo Smith; 1990
- "Plant Physiology"; L. Taiz and E. Zeiger; 1991
- "Cellular and Molecular Life Sciences"; K. Garg and C. Varshney; December 1980
- "Encyclopedia of Plant and Crop Science"; H. Plijel; February 2004
