List of Plants that are Used as Biological Indicators

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Biological indicators, which are also called bioindicators, are used to determine dangers that are to be found in the environment but may remain undetected. By using plants and animals to alert scientists and environmentalists to those dangers in the soil, in the air and in the water, it becomes possible to guard against those environmental dangers. The U.S. Environmental Protection Agency considers an indicator to be a measurable numeric value which is derived from calculating measurable environmental conditions over a period of time. These indicators have been compiled into an official “Report on the Environment.” They are derived from actual measurements with statistical properties. The purpose of such a study is to track changes over time and “identify major ecosystem stress.”

Some of the major plant bioindicators used to monitor this process include lichens, mosses, tree bark, bark pockets, tree rings, leaves and fungi. Lichens are made up of both algae and fungi. Strictly speaking, they are not really plants. Lichens grow on tree trunks and on rocks. They have observable reactions to changes in climate and air quality. They may die from pollutants in the environment, such as sulfur dioxide and nitrogen oxides. Pollution in water systems can also result in an observable depletion of the algae population.

Other plants that can be used as biological indicators include sunflowers. In a 2009 study, sunflower plants were treated with different levels of lead ions. Results indicated that a lower protein content was measured in all the treated plants. In another study algae were assessed for toxicity.

In yet another study, pine needles, as well as lichens and mosses, were used as plant bioindicators to determine the distribution pattern of aerial emissions from chemical plants, paper mills, mines and stainless steel works and other heavy metal industries. This process of monitoring the effects of pollution through the medium of living organisms is known as biomonitoring. It has advantages over the direct measurement of pollutants. One of these advantages is that it allows the long-term effects to be assessed in real terms of that pollution on the ecosystem. Bioindicators also gauge the cumulative effects of various kinds of environmental pressures, such as air pollution from different sources. In this and in other studies, pine needles have been demonstrated to determine levels of air quality for metal and sulphur pollutants.

Similarly, mosses have been shown in several studies to be very good bioindicators of air pollution by heavy metals. Scientists have used mosses as bioindicators since the 1960s. The reason they make such good bioindicators is that they derive most of their nutrients from air-borne particles as well as from rainwater. Studies done in Scandinavia have identified metal pollution by using mosses.

Research has been done on the effects of ozone airborne pollution on plants in order to understand the transport patterns of ozone air pollution at all local, regional and global levels. Ozone air pollution affects vegetation even in forests at remote locations, far from the factories and emission sites that are the cause of the pollution. The reason for this is that the airborne pollution travels downwind from industrialized urban areas to other places. In other studies, bioindicator gardens have been planted to measure the effects of damage to the ozone layer. Plants have been used that are particularly sensitive to ozone damage. These plants include common milkweed (Asclepias syriaca) and cut-leaf coneflower (Rudbeckia lacinata). Measurements of foliage injury and ozone damage have been developed and standardized in comparative studies which document how effectively these ozone sensitive plants can be used as biological indicators. Data sheets and monitoring protocols are available for scientific rating and these can be employed with a wide variety of bioindicators under different kinds of environmental conditions.

Resource by k.Pearson

My name is Kim, I am a volunteer at a local Zoo in Chicago, IL. I have been a volunteer for about 5 years now and love it. My full time job is at a vet just outside of the city. I am intrigued by the nature of animals and how they interact with one another.

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