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Issues

Ecological Problems

Pueraria montana has an apparently massive effect on the local ecology in the areas it invades, although few quantitative studies have been undertaken. The bulk of information about kudzu’s effect on other species comes from qualitative personal accounts made by government management agencies and other groups affected by invasions. However, almost all sources are in consensus as to how kudzu affects local flora. Kudzu spreads both horizontally and vertically, covering all other plants in a tick mat of leaves and stems, which blocks light from reaching them. Very few plants can grow under such low light conditions, and usually the weight of the kudzu alone can be a barrier to growth. For this reason, diversity in plant species is extremely limited in a region invaded by Pueraria montana. The decrease in plant species also has a negative effect on the diversity of native fauna. The elimination of native trees and brushes deprives native herbivores of food, and thus causes a huge gap in the region’s food chain.  It has also been stated that the decrease in diversity is especially critical in the Southeast United States, since that region is historically very genetically diverse due to the subtropical climate and the remainder of ice age ancestors.

Photo courtesy of Galen parks, Wikimedia Commons

Environmental Concerns

Pueraria montana has been found to have a significant impact on soil and atmospheric chemistry (Hickman 2009, Wiberly 2005). Hickman demonstrates that the nitrogen fixing capabilities of kudzu can cause important and potentially harmful environmental changes in areas it dominates (2009). He found that nitrogen cycling rates, amount of nitrogen available in soil, and amounts of atmospheric NO were all higher in invaded regions. High amounts of nitrogen in soil can be harmful to certain types of plants, which means kudzu may lead to a decrease in soil productivity. The emission of NO into the atmosphere is also a serious problem, since it leads to the creation of ozone and thus pollutes the air (Hickman 2009). Hickman states that there are already many government efforts to control NO emissions in the United States, especially in the southeast, and that an expansion of the range of Pueraria montana may largely offset these efforts. Also, another study found that Pueraria montana has the ability to emit isoprene, a hydrocarbon that is believed to protect plants from heat. Isoprene is known to influence tropospheric chemistry, specifically by increasing the amount of carbon monoxide, dioxide, and ozone. Kudzu emits larger amounts of isoprene when grown in hotter climates, and so will produce more in the sub-tropical climate of the Southeast United States. Therefore, the extensive invasion of kudzu poses a large threat to the environmental chemical balance.

Economic Effects

The negative effects of Pueraria montana on the Southeastern economy have been extensively documented. Kudzu has become a very large problem for the forestry industry, since invasions are difficult to eradicate and can rapidly spread over large areas. Ten years ago the total productivity lost by agricultural and forestry businesses was over $500 millon a year. This does not include the crop damage caused by diseases carried by kudzu. It has been found that kudzu is a carrier of Phakopsora pachyrhizi , or soybean rust, which is one of the most widespread and damaging diseases in the Southeastern soybean crop (Bonde et. al. 2009). Power companies also suffer from kudzu invasion since the weight of kudzu vine often pulls down wires and causes power outages. It has been estimated that the amount of money they spend annually to remove it from poles and wires is around $1.5 million per year. Railroads also must spend money to remove kudzu from tracks, but this value has not been estimated. Also not estimated but still significant is the value of private property that is lost to kudzu, since kudzu can invade privately owned forests and fields and can even envelop houses. These numbers are impressive, but since these figures are slightly outdated and there have been no large scale efforts to remove kudzu from the Southeast, it is likely that the amounts have increased significantly.

323 Comments

  1. By: Lonnie Alsobrook on November 21, 2011 at 9:19 am      Reply

    Respect to article author , some wonderful selective information . “It’s always too early to quit.” by Norman Vincent Peale.

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