Impacts of clear-cutting forests for solar
Converting forested land to massive industrial ground-mounted solar means clear-cutting trees, removing root balls and stumps, stripping topsoil and vegetation and grading. Subsurface trenching for underground lines also occurs.
Clear-cutting forests means all trees are removed. This impacts the microclimate, water, soil, nutrient cycling, carbon emissions, and the diversity and composition of plant and animal species.
Upon clear-cutting of forested trees, the microclimate of the piece of land is altered due to direct sunlight exposure to the ground that were previously shaded by the canopy of the trees and wind velocity. This can affect plants and animals, specifically invertebrates, as most organisms can live in a specific temperature range requirement. Research conducted on the effect of clear-cutting on rivers found that as trees were cut, the shading the trees provided was no longer present and river temperatures elevated considerably. Even a few degrees can make a huge difference to native plants, fish, and amphibians, and can cause a significant population decrease. Wind velocity increase caused by clearcutting can impact specific plants or animals, making it harder for them to grow in certain conditions.
The water cycle is also affected by clear-cutting of forested lands as trees are natural barriers and sinks for excess water, and can soften the impact of flooding and landslides in a forested area. As trees grow, they help trap and retain water within the topsoil and filter the water into the aquifer with time. If trees are removed, the water does not filter into the aquifer, but rather moves across the surface of the topsoil into nearby streams. This causes the topsoil to move with the water, resulting in a water body that has turned brown and thereby reduces water quality. This process also causes the nutrients in the topsoil to move from the soil to the water bodies, which also has harmful effects in streams and ultimately the oceans (toxic algae blooms).
As the water cycle is altered with removal of trees, the soil is also affected. As mentioned previously, when trees are cut down, the topsoil travels with the water to a watering body. This topsoil is filled with many beneficial nutrients such as nitrogen and phosphorous that enables vegetation growth. With the topsoil gone, the quality of the soil decreases substantially as they are nutrient depleted [will talk about in the next section]. Additionally, removal of trees causes the soil to be less compact as trees act as anchors for the soil. Removing these anchors can make the soil vulnerable to erosion. Tree removal can also remove the bacteria, fungi, and worms that maintain forest soil and prevent harmful diseases. Overall, the degradation of soil is a significant issue with clear-cutting forests.
The nutrient cycle is interconnected with the water cycle and soil degradation when trees are clear-cut and leads to misbalance in the cycling of different important nutrients, such as nitrogen, carbon, phosphorus, potassium, calcium, and magnesium. Research conducted in Connecticut, compared the nutrient cycling on undisturbed land compared to clear cut land. They found that clear-cut lands showed accelerated loss of nutrients, primarily with nitrogen. Nitrogen was found to be lost during the first year after cutting in equivalent amounts to undisturbed land nitrogen loss annually. Additionally, clear-cut lands lost cations, such as phosphorous, calcium, and magnesium, at a maximum of 20 times greater than on undisturbed land. Other research in North Carolina found that nitrogen mineralization and immobilization increased after clear-cutting while plant nitrogen uptake reduced in clear-cut areas. This causes increased movement of nitrogen and leaching of nitrogen into groundwater supplies at higher concentrations and causes an overall loss of nitrogen from the system.
As trees are clear-cut, they release carbon dioxide and therefore increase the ambient carbon dioxide levels in the surrounding areas. Trees function as carbon sinks, meaning they take up carbon dioxide and incorporate it in their woody biomass. Large-scale clearcutting can have an impact on the amount of carbon dioxide that is released into the atmosphere and can increase carbon dioxide levels in nearby areas. This reduces air quality and can have detrimental impacts on human health.
Finally, clear-cutting has substantial impact on the biota of the ecosystem. It causes habitat loss for animals that depend on trees for burrows, nests, food, security from predators and other uses. Animals that are displaced as a result of clear-cutting have to find new habitats and can often go into human settled areas. Those animals that cannot find new habitats to make their homes and find food become more vulnerable to predators. Additionally, vegetation is impacted by clear-cutting as it reduces landscape heterogeneity, meaning that the vegetation that regrows after a clear-cut are similar in their species composition. This makes these lands vulnerable to disease and invasive species because vegetation heterogeneity can have a bottleneck effect on the ecosystem. This heterogeneity is also called biodiversity, which is measured by the different amount of species in a hectare. In terms of invasive species, there have been specific cases of invasive species of ants replacing indigenous ant species as an indirect result of clearcutting procedures. The loss of few indigenous species can alter the entire balance of the ecosystem. Anther example of impacts of clearcutting on animals and plants, is the increase in prevalence of different diseases. An example is clearcutting creating new breeding groups for mosquitoes. The explosion of Lyme disease in the United States can also be traced to forest degradation since the subsequent ecological changes led to a larger mouse population, and ticks get the Lyme disease bacteria from mice.
In Southeastern Massachusetts, earth removal is a “thing.” Usually done under the ruse of removing large volumes of earth to build cranberry bogs, the impacts on our forests, biodiversity and water are incalculable. With solar, earth removal can be just a few feet for grading, or the project can serve as a ruse to “prepare” the site for solar as in the case of the AD Makepeace Co. and Borrego Solar projects in Carver and Wareham. This can impact soil depths ranging from several meters to several hundreds of meters. Earth removal, as well as the movement of workers and vehicles to do so, impacts soil quality and land degradation, dust emissions, leaching of nutrients and other chemicals into ground water supply.
Soil quality was mentioned above, but in brief, top soil plays a significant role in providing nutrients and stabilizing the soil from erosion. When trees are removed, the soil is no longer anchored and moves easily. This allows for erosion and loss of vital nutrients to occur. It also prevents native plants from returning to the area, as the conditions of the soil have changed and likely no longer support the necessary nutrients needed for the native plants. The process of earth removal results in lands that are severely degraded as it alters the soil profile and the natural soil layer.
With earth removal and the movement of soil, the area of earth removal is clouded in dust emissions. Dust emissions may result in exposures to metals or other toxic air contaminants that have been trapped in the soil for up to decades. Dust emissions also travel with the wind velocity, so there can be potential hazardous impacts to human health for unknowing nearby town residents and workers. Potential toxic compounds found in dust emissions are arsenic, asbestos, cadmium, hexavalent chromium, lead, mercury, nickel, and polychlorinated biphenyls.
Finally, the earth removal process alters the nutrient and chemical cycling. It limits the nutrient cycles by eliminating the main source of nitrogen and carbon fixation – vegetation. As plants store nutrients within themselves, their destruction severely decreases the amount of nutrients present in the soil. Additionally, soils have many different elements that are present at varying depths, including iron, lead, copper, zinc. Earth removal causes these elements to leach out of the soil and potentially pollute waterways. This is clearly seen in areas of iron leaching, causing waterways and streams to turn a redish color, telling sign of iron being oxidized.
Construction of Solar Panels
Finally, the construction of solar panels has negative ecological impacts. These include carbon emissions from solar panel production and construction, noise pollution from construction, air pollution from construction and water pollution from solar panels themselves.
Solar panels are made of silicon, a material that requires high levels of heat for shaping, which releases CO2. Solar panels generate around 50g of CO2/kWh during their initial years of operation. CO2 is also emitted during the construction from trucks, machinery, and other heavy equipment that are used to install the solar panels.
Ecological impact of solar panel construction also includes noise pollutions, which is often above 90dBA. This is relative to the sound of a lawn mower. Noise levels above 80-85 dBA are considered harmful to human health. Noise impacts can have effects on health, such as stress, sleep disturbance, high blood pressure and even hearing loss. Noise levels impact animals differently depending on species. Some animals cannot hear the normal human levels, therefore it may not impact them, however other animals are more sensitive than humans and noise can mess with natural cycles within an organism. For example, some studies have shown that loud noises cause caterpillars’ hearts to beat faster and bluebirds to have fewer chicks.
Finally, construction on solar panels can impact water quality, as the surface water and groundwater close to construction site can become polluted with various materials used during construction work, Some examples of pollutants include, volatile organic compounds (VOCs), paints, glues, diesel, oils, other toxic chemicals, and cement. Because plants are not present to filter out the toxic chemicals from construction, the groundwater supply may become contaminated and can harm human health if ingested.
Importance of Forests
Forests are important as they are homes to many different species and help with other abiotic components. Important ecosystem services provided by forests include generation of wood and pulp, mitigation of flood waters by tempering the runoff hydrograph, filtration of pollutants from rainwater and air, moderation of local air temperatures, creation of scenic and recreational opportunities, and hosting of endangered and protected species.
Keenan, R. J. (1993). JP (HAMISH) KIMMINS. The ecological effects of clear-cutting. Environmental Review, 1, 121-144.
Vitousek, P. M. (1981). Clear-cutting and the nitrogen cycle. Ecological Bulletins, 631-642.
Bormann, F. H., Likens, G. E., Fisher, D. W., & Pierce, R. S. (1968). Nutrient loss accelerated by clear-cutting of a forest ecosystem. Science, 159(3817), 882-884.