Biology Textbook - VUNMC 2000

Chapter 7. THE BIOSPHERE LEVEL OF ORGANIZATION OF LIFE

7.12. BIOLOGICAL METHODS OF ENVIRONMENTAL PROTECTION

Biological Methods for controlling agricultural pests and protecting the environment from pollution are gaining increasing importance in human practical activity.

7.12.1. PLANTS AND THEIR ROLE IN ENVIRONMENTAL PROTECTION

Green plants form the foundation of the biosphere. Through them, a connection is established with the Sun, the source of energy for life for the vast majority of the planet's inhabitants. Plants produce organic matter, serving as the primary source in the food chain, and supply the atmosphere with molecular oxygen, which is essential for Respiration and maintaining the integrity of the ozone layer that protects organisms from the harmful effects of cosmic radiation.

Vegetation has a positive impact on the microclimate and hydrological regime, enriches the soil with humus, and protects against erosion. Plants participate in biogeochemical cycles and produce BIOLOGICALLY ACTIVE SUBSTANCES known as phytoncides (from the Greek "phyton" meaning plant and "cide" meaning to kill). These substances purify the air from pathogenic microorganisms by destroying them or suppressing their GROWTH AND DEVELOPMENT, while their leaves trap significant amounts of dust. Plants and vegetation as a whole, being a source of aesthetic pleasure, have a beneficial effect on human mental well-being. Plant communities also serve as habitats for representatives of other kingdoms of the living world.

Plants are an essential component of the human diet, providing CARBOHYDRATES, vegetable fats, Proteins, Vitamins, mineral salts, and organic acids, as well as serving as animal feed and raw Materials for the textile, pharmaceutical, perfumery, and other industries.

Recently, increasing attention has been paid to plants as environmental indicators and purifiers. Their role in these processes cannot be overestimated, although under conditions of high pollution, they themselves experience severe stress and frequently perish. The primary task is to identify plants capable of "detecting" negative environmental shifts and "warning" humans of danger. Sometimes, even the most precise instruments fail to register certain toxic substances at relatively low concentrations. However, when pollutants enter the food chain, they can accumulate to high concentrations at the final stages and become a source of harm to humans.

Plants can be used as indicators of environmental conditions. Lichens and conifers, especially spruce, are extremely sensitive to atmospheric sulfur dioxide pollution. Gladioli, conversely, are resistant to this gas but react negatively to increased fluorine levels; when fluorine is present in the atmosphere, their upper leaves begin to die off. At low concentrations of hydrogen chloride in the air, the leaves of alfalfa and radishes are damaged. Environmental pollution with copper causes the petal color of poppies and roses to turn blue or even black; under METABOLISM/18.html">The Influence of excess zinc, poppy flowers may become double.

Various toxic substances are often present in the environment, and their combined effect on an Organism can be more lethal than that of each substance individually at the same concentration. This synergism may not be detected by Physicochemical methods of studying environmental pollution, but it negatively affects organisms, including plants. By observing plant reactions to this impact, we can assess the ecological situation much more accurately.

Plants cleanse the atmosphere, Water, and soil by absorbing harmful substances and accumulating them within their Tissues. Different species accumulate various substances at different rates and exhibit varying degrees of resistance to them. This must be taken into account when establishing sanitary-protection zones and selecting plants best suited to the given conditions. Near industrial enterprises that emit hydrogen chloride into the atmosphere, it is recommended to plant European ash, silver poplar, aspen, oriental arborvitae, and other species capable of accumulating chlorine while showing increased resistance to it. Balsam poplar and red-osier dogwood are resistant to sulfur dioxide and capable of absorbing it in large quantities. Cultivating them in areas where this gas might be present in the atmosphere is highly desirable. Poplar is a fast-growing tree, and shade-tolerant dogwood can be planted beneath it. Horse chestnut, black poplar, and small-leaved linden absorb lead. Red elderberry and common lilac possess a high phenol-accumulating capacity. Lingonberries and oaks accumulate reactive substances even when located far from the source of emission.

The value of plants capable of reducing or completely neutralizing large amounts of the toxic substances they absorb is increasing. The toxicity of sulfur dioxide decreases in plant leaves due to its conversion into sulfates. Phenol, benzene, toluene, and xylene absorbed by plants from water and air undergo detoxification in cereal grasses. A number of mutagens are inactivated by burdock.

The "protective" properties of plants are also widely utilized by humans for other purposes. Red elderberry and yellow archangel help get rid of rats and mice. Rodents cannot tolerate the scent of hound's-Tongue either; when planted in a garden, it protects fruit trees from them. Elderberry is recommended to be planted near granaries and grain storehouses. Mustard protects peas from the pea moth, daylilies protect bulbous plants from millipedes, coriander repels fruit tree pests, and marigolds help combat harmful nematodes. Onions and garlic are unappealing to weevils, mites, wireworms, and other pests. Bud mites do not attack currants if onions are grown between the bushes and left over the winter. It is recommended to treat fruit and berry crops 2–3 times with a celandine decoction to protect them from pests. Gooseberry sawfly larvae and codling moth caterpillars are vulnerable to it. An infusion of fresh leaves of greater celandine is used to spray houseplants infested with aphids and scale insects.

The Use of plants and preparations made from them can partially replace the chemical pesticides that humans use in pest control.

Plants are used as test organisms to check the environment for various pollutants. The analysis of diatoms, which accumulate radioactive substances in their bodies in large quantities (up to 2,000 times higher than in the surrounding environment), can indicate the purity or degree of pollution of the studied sea or ocean waters. Higher plants are also capable of accumulating radioactive substances in large quantities under "favorable" Background levels (oak, lingonberry).