Biological weathering is one of the important natural processes that contributes to the breakdown of rocks and changes in their properties at the Earth's surface. It occurs as a result of the activities of living organisms, particularly plants, microorganisms, and animals. Biological weathering can be physical when living organisms cause rocks to break apart, or chemical when they produce substances that help dissolve minerals and alter their composition. This process is closely associated with soil formation, as weathering provides the minerals and inorganic materials that contribute to soil formation, while living organisms add the organic matter necessary for its development. Plant roots are among the most important biological factors involved in rock breakdown. As roots grow through the soil and reach cracks and fractures in rocks, they continue to expand within them. As the roots increase in size, pressure on the sides of the cracks increases, gradually widening the cracks and breaking the rocks into smaller pieces. This process increases the surface area of rocks exposed to water, air, and other environmental factors, thereby accelerating subsequent weathering processes. The effect of plants is not limited to physical fragmentation, as roots can also contribute to chemical weathering. Plants, roots, and associated organisms produce organic compounds and acids that help dissolve some of the minerals present in rocks. In addition, the respiration of roots and microorganisms in the root zone increases carbon dioxide concentrations, which affects the chemistry of soil and water and can accelerate the weathering of certain minerals. Lichens, algae, bacteria, and fungi contribute to the early stages of colonization of rock surfaces. Lichens, which consist of a symbiotic association between fungi and algae or algae-like organisms, can grow on bare rocks and produce compounds that help dissolve certain minerals. As their activity continues, small cavities and cracks develop on the rock surface, while their organic remains accumulate, creating conditions that facilitate the growth of larger organisms and plants. Bacteria and fungi also play an important role in chemical weathering through their interactions with minerals and the production of organic compounds that help release certain mineral elements. Studies indicate that microorganisms can be important agents in weathering processes, particularly at the interface between minerals, water, and living organisms. The Role of Animals in Rock and Soil Breakdown Animals also contribute to biological weathering both directly and indirectly. Burrowing animals, such as rodents, insects, and worms, help break up soil and rock materials and transport them between different layers. Burrowing also increases the exposure of rocks and mineral materials to water, air, and microorganisms, which can enhance other weathering processes. Al-Mustaqbal University – The First University in Iraq
  الهدف الرابع : التعليم الجيد