How have human activities caused desertification ? Explain.

Explanation

Human activities contribute to desertification-
1. Deforestation- Humans cut down trees to serve their own purpose like construction of houses and roads which is the main cause of desertification.
2. Improper farming practices-If same crop is grown continuously, it makes the soil deficient of nutrients resulting in the loss of fertility of soil.
3. Soil Erosion-That is by different human activities like construction of houses and industrialization.
Or
An algal bloom is the phenomenon of excessive growth of planktonic forms in a nutrient rich water body. As the planktonic species multiply on the surface they form a layer that eventually covers the entire surface of the water body. They block sunlight, which does not reached submerged aquatic plants that may have a role in supplying necessary nutrients to other aquatic life forms and keeping the water clean. Some algal species can release toxic substances.
Due to the high respiratory needs of such a huge concentration of biomass on the surface, the biological oxygen demand (BOD) of the water body increases, causing many of the life forms to die, their carcasses further contribute to the deterioration of the quality of the water content.