HUMAN Impact on Ecosystems

What is Ecosystem Sustainability? The ability for an ecosystem to maintain ecological processes On their own, ecosystems are sustainable, that is, they perpetuate themselves indefinitely and require little to no new materials each year. A key to their sustainability is their continual recycling of nutrients (remember the nitrogen, carbon and water cycles). Many human activities however, are not sustainable, and alter the state of ecosystems.

What is Ecosystem Sustainability?

Habitat Loss Humans have had major impacts on natural ecosystems over the past 150 years. Due to human expansion, habitats have been lost or fragmented. “Habitat fragmentation” is the splitting of large habitats into many smaller ones, resulting in disrupted natural activities for plants and animals. Habitat loss & habitat fragmentation reveal the effects of human activities on ecosystems.

The Effects of Land and Resource Use All of the land around us, even in cities, was once a part of an ecosystem. We use the land for things like urban development, agriculture, industry, mining and forestry The processing & export of resources like lumber, grain, uranium are very important to Saskatchewan’s current economy.

The Effects of Land and Resource Use “Resource use” refers to the ways we obtain and use naturally occurring materials. Most products you use every day involve the use of some natural resources in their production.

The Effects of Deforestation “Deforestation” is the clearing or logging of forests for human use. some land is never reclaimed or replanted.

The Effects of Deforestation Deforestation results in soil degradation = wind & water erode topsoil & leave bare land behind Topsoil: the upper layer of soil, where most of the nutrients, water and air are found for plant growth Deforestation is still occurring in many tropical rainforests.

The Effects of Agriculture The need for agricultural land has resulted in draining of wetlands. Wetlands are special ecosystems that contain completely waterlogged soil for long periods of time. Wetlands contain high biodiversity, and also filter many impurities out of the water. Because they hold large amounts of water, they can help prevent flooding.

The Effects of Agriculture agricultural crops that are planted are often one species = monoculture This reduces biodiversity, and leaves the crop vulnerable to pests or disease. Polycultures, of many plant species, are more economically and biologically diverse.

The Effects of Agriculture In fields left without crops, water & wind can cause erosion. In wet areas the soil can become compacted. = Soil particles are squeezed together so there is no room for water or air to enter the soil. This is due to farm animals or vehicles.

The Effects of Agriculture Because of soil compaction water runs off the soil instead of soaking in. = decreases leaching. Aeration, which involves removing small plugs of soil, loosens soil & can reduce run-off.

Resource Exploitation Humans use resources for jobs, materials, food, shelter and energy. Exploitation can lead to habitat loss, soil degradation & contamination of water supplies.

Resource Exploitation Overexploitation is the extraction of resources until they are gone. Can result in extinction Example: passenger pigeon Food webs can be greatly affected for long periods of time especially in keystone species species that greatly influences the population numbers and health of an ecosystem Examples: Sea Otter, Coyote, Beaver

Resource Exploitation

Ecological Restoration Many mining and resource exploitations require reclamation efforts. Reclamation attempts to reduce environmental impacts of exploitation, & restore the original (or functional) habitats. Returning young coho salmon to rivers near Port Alice can help maintain sustainability.

Ecological Restoration

Ecological Restoration Current ecological restoration & usage guidelines often involve Traditional Ecological Knowledge from Aboriginal councils. Traditional Ecological Knowledge is passed down from generation to generation in Aboriginal cultures. Knowledge is found in stories, cultural beliefs, rituals, community laws songs, & traditional practices.

Traditional Ecological Knowledge This knowledge reveals what past conditions were like, & how the ecosystem & humans interact. Fire suppression, enforced in Saskatchewan for over 100 years, has led to recent issues like Dwarf Mistletoe infestation & huge wildfire losses. Traditions such as the “Spring burn” allow ecological renewal. https://www.youtube.com/watch?v=vn1ym5r7pqg