Explain how human impact can lead to succession in ecosystems.

Ecological succession refers to the changes taken place in a forest over a particular period of time.

Succession is usually influenced by environmental factors such as water regimes, soil type, climate, vegetation history, and invasive species.  

Humans interventions affect all of the above-mentioned factors.

Human activities such as fragmentation of forests, clearing of forests for agricultural practices, construction of dams, civilization, logging et cetera drastically reduce the biodiversity of a forest.

This reduction of biodiversity forms the foundation for a secondary succession of a forest.

b. the carbon cycle ensures living things have a source of hydrogen