What are 2 ecosystems altered or built by humans?

Question

Any help is appreciated

Answer 1

Agricultural fields are ecosystems built by humans.

All ecosystems have been altered by humans -- just pick one.  Temperate deciduous forests have been fragmented and harvested.  We have lost top predators in many parts.  We have introduced exotic plants and animals.  CO2 levels are affecting plant growth, nitrogen deposition is adding nutrients and acid rain has altered soil chemistry.  Unfortunately this is true for all ecosystems.  

Answer 2

In biology, abiotic components are non-living chemical and physical factors in the environment. Abiotic phenomena underlie all of biology, but at the same time both are better forgotten in the direct analysis of life as such. More generally, the sciences concentrated on lower level explanation are better forgotten when dealing with higher level phenomena.

From the viewpoint of biology, abiotic influences may be classified as light or more generally radiation, temperature, water, the chemical surrounding composed of the terrestrial atmospheric gases, wind as well as soil. The macroscopic climate often influences each of the above. Not to mention pressure and even sound waves if working with marine, or deep underground, biome.

Those underlying factors affect different plants, animals and fungi to different extents. Some plants are mostly water starved, so humidicity plays a larger role in their biology. Archaebacteria require very high temperatures, or pressures, or unusual concentrations of chemical substances such as sulfur, because of their specialization into extreme conditions. Certain fungi have evolved to survive mostly at the temperature, the humidity, the stability, and the (grantedly biological) feed of nutrients present in the human v****a: genus Candida.

In biology, biotic components are the living things that shape an ecosystem. They are in entirety, anything that affects a living organism that is itself alive. Such things include animals which consume the organism in question, and the living food that the organism consumes. As opposed to abiotic components (non-living components of an organism's environment, such as temperature, light, moisture, air currents, etc.), biotic components are the living components of an organism's environment, such as predators and prey.

For example, if one were to examine a tundra ecosystem for biotic and abiotic components, one would observe things like the extreme temperatures of the day and night, the fast winds, the heavy amount of sunlight, and scarcity of water as abiotic (or non-living components) in the environment. One would observe that for a quail living in the desert, living elements like the quail's prey (insects, seeds, etc.) and predators (coyotes, sparrow hawk, gold eagles, etc.) make up the biotic components of the quail's environment.