why do plants need carbon dioxide to grow

Literally thousands of laboratory and field experiments have conclusively demonstrated that enriching the air with carbon dioxide stimulates the growth and development of nearly all plants. They have also revealed that higher-than-normal CO2 concentrations dramatically enhance the efficiency with which plants utilize water, sometimes as much as doubling it in response to a doubling of the air's CO2 content. These CO2-induced improvements typically lead to the development of more extensive and active root systems, enabling plants to more thoroughly explore larger volumes of soil in search of the things they need. Consequently, even in soils lacking sufficient water and nutrients for good growth at today's CO2 concentrations, plants exposed to the elevated atmospheric CO2 levels expected in the future generally show remarkable increases in vegetative productivity, which should enable them to successfully colonize low-rainfall areas that are presently too dry to support more than isolated patches of desert vegetation.

Elevated levels of atmospheric CO2 also enable plants to better withstand the growth-retarding effects of various environmental stresses, including soil salinity, air pollution, high and low air temperatures, and air-borne and soil-borne plant pathogens. In fact, atmospheric CO2 enrichment can actually mean the difference between life and death for vegetation growing in extremely stressful circumstances.

In light of these facts, it is not surprising that Earth's natural and managed ecosystems have
already benefited immensely from the increase in atmospheric CO2 that has accompanied the progression of the Industrial Revolution; and they will further prosper from future CO2 increases. Join us as we explore these and other important benefits that rising atmospheric CO2 concentrations are bestowing on plants. Carbon dioxide emissions resulting from the burning of fossil fuels should not be feared; they are something to be celebrated! To learn more, click on one of the categories below Plants need CO2 to live. So is more of it a good thing?

Published: Nov 7th, 2009 We do not yet know enough to make adequate projections of the global trends for plant life in a world with higher levels of carbon dioxide, or CO2. It is clear, however, that there can be both positive and negative responses. One of the first things taught in biology class is that animals breathe in oxygen and exhale CO2, while plants take in CO2 during the day and release oxygen. In a process called photosynthesis, plants use the energy in sunlight to convert CO2 and water to sugar and oxygen. The plants use the sugar for food food that we use, too, when we eat plants or animals that have eaten plants and they release the oxygen into the atmosphere.

If it were not for plants, we would have no oxygen in our air! So, if we re putting more CO2 into the atmosphere by burning fossil fuels, you might expect plants to grow better. But the story is not quite that simple. When biologists have grown crops like wheat, soybeans, and rice inside greenhouses with extra CO2 present, the plants have indeed grown more rapidly and more abundantly. For the past several years, scientists all over the world have also been doing a series of experiments called Free-Air Concentration Enrichment, or FACE. Instead of using greenhouses, they grow crops in open fields to give them the most natural environment possible and pump in extra CO2 from a network of pipes.

The results of these experiments have shown that the crops do not thrive as well in this environment. Plants do need CO2, but they also need water, nitrogen, and other nutrients. Increase one of these without increasing the others and there s a limit to how much the plants will benefit. Some do not grow much more at all. Others, like wheat, grow bigger but end up with less nitrogen. As a result, insects end up eating more to get the nitrogen they need. The nutritional value of food plants would be similarly reduced for other animals including humans. Also, we could end up with vegetables that have too much carbon perhaps producing spinach that would be very tough to chew! Posted in,