Almost everywhere we went, humankind erased a world of wonders, changing the way the biosphere functions. For instance, modern humans arrived in Europe and Australia at about the same time – between 40 and 50,000 years ago – with similar consequences.

In Europe, where animals had learned to fear previous versions of the bipedal ape, the extinctions happened slowly. Within some 10 or 15,000 years, the continent had lost its straight-tusked elephants, forest rhinos, hippos, hyenas and monstrous scimitar cats.

In Australia, where no hominim had set foot before modern humans arrived, the collapse was almost instant. The rhinoceros-sized wombat, the ten-foot kangaroo, the marsupial lion, the monitor lizard larger than a Nile crocodile, the giant marsupial tapir, the horned tortoise as big as a car – all went, in ecological terms, overnight.

A forest is a large area dominated by trees. Forests are the dominant terrestrial ecosystem of Earth, cover approximately 30% of the world's land, and contain 80% of the plant biomass.

Protists - members of an informal grouping of diverse eukaryotic organisms that are not animals, plants or fungi, and are grouped together for convenience, like algae or invertebrates. Besides their relatively simple levels of organization, protists do not necessarily have much in common. 

Subdivisions of Protists

Protozoa the unicellular "animal-like" - Flagellata, Ciliophora, Amoeba, Sporozoans.

Protophyta the "plant-like" - mostly unicellular algae.

Molds the "fungus-like" - slime molds and water molds.

Archaea and bacteria (eubacteria) are single-celled organisms that do not have a nucleus or organelles. Archaea have a distinct evolutionary history and biochemistry compared with bacteria.

Archaea - a domain of single-celled microorganisms. These microbes are prokaryotes. Archaea can survive in extreme and harsh environments like hot springs, salt lakes, marshlands, oceans, gut of ruminants and humans.

Bacteria - a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a number of shapes, ranging from spheres to rods and spirals. Eubacteria are ubiquitous and are found in soil, hot springs, radioactive waste water, Earth's crust, organic matter, bodies of plants and animals, etc.

A genetically modified organism (GMO) is any organism whose genetic material has been altered using genetic engineering techniques (i.e., a genetically engineered organism). GMOs are used to produce medications and genetically modified foods, and are widely used in scientific research and the production of other goods. 

A more specifically defined type of GMO is a "transgenic organism." This is an organism whose genetic makeup has been altered by the addition of genetic material from an unrelated organism. Typically GMOs are organisms whose genetic makeup has been altered without the addition of genetic material from an unrelated organism.

A fungus is any member of the group of eukaryotic organisms that includes unicellular microorganisms such as yeasts and molds, as well as multicellular fungi that produce familiar fruiting forms known as mushrooms. These organisms are classified as a kingdom Fungi, which is separate from the other eukaryotic life kingdoms of plants and animals. Fungi do not use photosynthesis to create energy.

A study of marine mammals, birds, reptiles and fish shows a decline of 49% in the size of marine populations between 1970 and 2012.

Humans alone outweigh all the remaining terrestrial mammals on the planet by about seven times, the livestock weighs double that again. 

Species-rich habitats are being converted to pasture and feed crops as the human appetite for meat swells. By 2050, given current trends, 15 countries, which harbor the largest number of species will likely increase the lands used for livestock production by 30%-50%—some 3,000,000 square kilometers.
The habitat loss is so great that it will cause more extinctions than any other factor, particularly when coupled with other deleterious effects of livestock production, including climate change and pollution. Many species will be lost.

Forest trees and their root fungi share resources and information. The plant makes and delivers food to the fungus; the fungus increases the plant’s water and mineral absorptive powers. Trees of different species can communicate with and support one another via their mycorrhizae. 

It is known, that plants can communicate with unrelated species through the air. Plants getting chomped by herbivores, eaten by insects or attacked by pathogens release volatile chemicals that are sensed by neighboring plants, who up their defenses pro-actively.