Plants' Resilience: Adapting To Air Pollution

Plants are sensitive to their environment, and air pollution can have a detrimental effect on their growth and development. However, plants are also resilient and can adapt to their surroundings through genetic changes. As urban pollution, traffic emissions, and shrinking habitats place new pressures on plants, they are forced to evolve and develop new traits to survive. This evolution happens through changes in their DNA, which acts as an instruction manual for growth and development. While these genetic accommodations may allow plants to survive in polluted environments, there may also be evolutionary costs, such as reduced reproductive success or life expectancy. Understanding how plants adapt to air pollution is crucial for designing effective vegetation barriers in urban areas to improve air quality and combat climate change.

Plants' ability to absorb carbon dioxide is affected by air pollution

Plants are incredibly important to human survival. They form the basis of natural ecosystems and absorb about 30% of all the carbon dioxide emitted by humans each year. Plants use sunlight, carbon dioxide, and water to photosynthesize and produce oxygen and carbohydrates for energy and growth.

However, plants' ability to absorb carbon dioxide is affected by air pollution. As global temperatures increase due to climate change, the amount of carbon dioxide released through plant respiration also increases. This has implications for the amount of carbon emissions from burning fossil fuels that plants can absorb. Warmer temperatures also affect the photosynthesis and respiration processes in plants, potentially reducing their capacity to absorb carbon emissions.

Elevated carbon dioxide levels in the air can also restrict plants' ability to absorb nutrients, particularly nitrogen, which is essential for crop growth. Research has shown that the concentration of nitrogen in plant tissue is lower in environments with high levels of carbon dioxide, regardless of whether plant growth is stimulated. This reduced nitrogen content can lead to decreased protein levels in crops, impacting their quality and nutritional value.

Additionally, plants may adapt to air pollution through genetic changes. Urban pollution, traffic, and shrinking wild spaces have been observed to cause genetic variations in plants, which may offer new traits that increase their chances of survival and reproduction. However, there can be evolutionary costs to these adaptations, as warned by Wirgin, an expert in environmental medicine. For example, a plant that becomes less sensitive to a pollutant may face trade-offs such as reduced reproductive ability or increased sensitivity to other stressors.

Plants' genetic makeup changes in response to air pollution

Plants, like all other organisms, experience constant exposure to natural forces, and their genetic makeup is substantially impacted by environmental factors such as fluctuations in temperature, light intensity, and water availability. The dramatic economic and technological progress driven by humans has also introduced additional stressors, including heavy metal pollution, radiation exposure, and xenobiotic chemicals.

The impact of air pollution on the genetic makeup of plants is an area of ongoing scientific research. While the specific nature of adaptations is not generally well-known, studies have suggested that plants may respond to air pollution through changes in their genetic makeup. For example, recent studies in poplar and spinach suggest that increased production of the enzyme superoxide dismutase may be a key factor in adapting to sulphur dioxide pollution.

Transgenic plants, which can be intentionally altered to be more sensitive to particular pollutants, are also being explored as a potential tool for sensing and evaluating environmental pollution. However, it is important to recognize that plants have unique mechanisms of uptake, distribution, storage, compartmentalization, and metabolism of various pollutants, which can influence their response to air pollution and potentially lead to false outcomes in genotoxicity assays.

In urban areas, where pollution, traffic, and shrinking wild spaces are prevalent, scientists have observed genetic changes in various organisms, including plants. These genetic accommodations increase the odds of survival and reproduction, allowing these new traits to be passed on to future generations. While the specific genetic changes in plants in response to air pollution are still being studied, the overall impact of air pollution on the genetic makeup of plants and other organisms is becoming increasingly evident.

It is worth noting that while plants may adapt to air pollution through genetic changes, there can be evolutionary costs to these adaptations, as warned by environmental medicine expert Wirgin. A species may gain an advantage in terms of survival, but it may also experience trade-offs in terms of reproduction, life expectancy, or sensitivity to other stressors.

Air pollution impacts plant growth and development

Air pollution has become a serious challenge in many countries, with multiple emission sources continuously adding particulates and gaseous pollutants to the environment. Air pollution impacts plant growth and development in various ways, and their effects vary among different plant species.

Air pollutants influence the morphological, physiological, and biochemical status of plants. For instance, studies on poplar and spinach suggest that increased production of the enzyme superoxide dismutase may be a key factor in adapting to sulphur dioxide. Other adaptations involve morphological and anatomical features. For example, plants can absorb, adsorb, and catabolize atmospheric pollutants, and certain biophysical traits can enhance air pollution abatement.

The specific mechanisms of adaptation are not yet well understood. However, urban pollution, traffic, and shrinking wild spaces have been causing genetic changes in plants. These changes may offer new traits that increase the odds of survival and reproduction, leading to the propagation of these traits throughout a population.

The costs of adaptation are also important to consider. As biologist Wirgin notes, adaptations that make a species less sensitive to a pollutant may come at the expense of reduced reproductive ability, decreased life expectancy, or increased sensitivity to other stressors.

To assess the impact of air pollution on plants, methods such as OTC and FACE are used. However, most studies focus on individual pollutants like ozone or particulate matter, rather than investigating the combined effects of multiple pollutants. Additionally, few studies differentiate the effects of particulate matter based on its composition or focus on native plant species in lower-middle-income countries. As a result, there is a need for more comprehensive research to fully understand the effects of air pollution on plant growth and development.

Vegetation barriers can be designed to reduce air pollution

Vegetation barriers are a promising method for reducing air pollution, particularly in urban areas. They can be designed to act as a physical barrier between pollution sources and people, effectively extending the distance between them. This is especially important for pedestrians, who are more vulnerable to the effects of air pollution than those travelling by car or public transport.

The design of vegetation barriers must consider contextual conditions, such as the topography of the built environment and local meteorological conditions. This is because the impact of vegetation barriers on pollutant dispersion is influenced by interactions with airflow and turbulence. For example, trees and bushes can modify near-road concentrations of pollutants by capturing them or altering airflow patterns. This can result in either reduced dispersion through slower wind speeds or enhanced dispersion due to increased air turbulence as the pollutant plume is lifted over the vegetation. Therefore, the height, thickness, coverage, porosity, and density of the vegetation barrier are all important factors to consider.

The species of plants selected for vegetation barriers is also critical. Different plant species have varying abilities to absorb and retain pollutants. For example, urban trees have been shown to remove gaseous pollutants like O3, PM10, NO2, SO2, and CO permanently from the air. However, they only temporarily retain particles, which can later be re-suspended into the atmosphere during turbulent winds or dropped to the ground with leaf and twig fall. Additionally, certain plants may be more suitable for specific local meteorological conditions.

Vegetation barriers can also provide multiple ecosystem services beyond air pollution reduction. These include ambient cooling and microclimate regulation, storm water attenuation, improved mental and physical health, biodiversity support, and climate change mitigation and adaptation. Thus, vegetation barriers can be a cost-effective and multifunctional solution for urban areas aiming to improve air quality and enhance the well-being of their residents.

Air pollution can cause physical damage to plant leaves

Plants are among the first victims of air pollution. They are particularly vulnerable because they are fixed in place and cannot move to escape the pollution.

Particulate matter, including metals, can settle on leaves, impacting the plant's ability to photosynthesise. Pollutants can also affect the stomata, the site of gas exchange on the leaf surface, leading to excessive water loss. During high heat, plants may emit volatile organic compounds (VOCs) such as terpenes, which contribute to summer air pollution.

Plants may adapt to air pollution through genetic changes. For example, studies suggest that increased production of the enzyme superoxide dismutase may be a key factor in plant adaptation to sulphur dioxide pollution. However, there may be evolutionary costs to these adaptations, as species may become less sensitive to a pollutant but face trade-offs in terms of reproduction, life expectancy, or sensitivity to other stressors.

Frequently asked questions