Human activities can have similar, wide sweeping impacts on individuals, populations, communities and ecosystems. When humans clear cut forests, this deforestation can result in loss of habitat for organisms. Habitat loss leads organisms to migrate to new habitats, which may become over-populated given limited resources. This can result in population decline of several species. Burning of fossil fuels in industry and transportation can lead to an increase in greenhouse gas in the atmosphere which may lead to climate change.
A changing climate means changing abiotic factors in an ecosystem such as temperate and rainfall, which may lead populations to migrate to new locations with a more suitable climate which could result in overpopulation, a lack of resources and sharp population declines. Burning fossil fuels may also lead to acid rain, which can severely impact the producers in an ecosystem and affect aquatic biomes.
Additional human impacts may include water and land pollution or the damming of rivers. Positive activities humans can undertake such as conservation and recycling can be included to highlight how they serve to mitigate negative impacts.
Ecologists often plan and conduct investigations to model or predict how changes in environmental conditions may impact individuals and ecosystems.
For example, an ecologist may plan an investigation to model how changing ocean temperature in the marine biome may impact growth of kelp by placing small kelp populations in different saltwater tanks of different temperatures to simulate predicted changes in ocean temperatures. After collecting data on population changes in the kelp in the tanks, the ecologist may enter that data into a computer simulation to predict how the changes measured in the investigation may impact otter populations which feed upon the kelp.