How do plants conduct chemical weathering?

Weathering is the process of breakdown of rocks, minerals, etc. It can be classified as either physical weathering or chemical weathering. Plants contribute to both the physical and chemical weathering. Plant roots grow and extend in the subsoil. This causes cracks and fissures in the rocks or widening of existing cracks, thus causing physical weathering. Plants also change the chemical conditions in the areas surrounding them and causes chemical weathering. Plants can produce humic acids, which helps dissolve minerals. The acids generated by live or decaying plants help in breaking down aluminum and iron compounds in the subsurface. Another example is growth of lichens on exposed rocks. Plants may also contribute to the growth and survival of microorganisms that cause weathering, such as mycorrhizal fungi. 

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