Ecology Putting it all together What is an ecosystem? O Ecosystem – all of the living organisms that share a region and interact with each other and their non-living environment. Can differ in size and features. O Abiotic factors – non living components of an ecosystem O Biotic Factors – living organisms and their products that occupy an ecosystem 3 Types of Ecology O Ecosystem Ecology - integrated study of all living and nonliving factors that operate within an ecosystem framework. Includes food webs, biogeochemical cycles Community Ecology O studies how populations of different species interact within a given ecosystem. Includes ecological relationships: Competition, Predation Mutualism (Symbiosis, Commensalism and Parasitism), feeding relationships and ecological pyramids Population Ecology O deals with the dynamics of species populations and how these populations interact with the environment. It is the study of how the population sizes of species groups change over time and space. Population ecology O A population is the number of individuals of a single species that reside in a given area. O limiting factors, tolerance and optimal ranges and carrying capacities of a given species. An integrated approach Ecosystem • Abiotic and biotic • Cycles/food webs Community • Interactions between species • Competition, predation, mutualism Population • Growth of single species • Carrying capacity, limiting factors, range What is the value of ecosystems? O Why do we need ecosystems? O What value are they to us when we can grow our own crops/livestock? Cultural value of ecosystems O Cultural services – recreational, aesthetic and spiritual experiences we receive when we interact with natural surroundings. Eg. Ecotourism Products O Ecosystem Products – ecosystems produce many of the things we use or consume every day. These include food, medicine, water and resources. Services O Regulatory and protective services – ecosystems protect us from natural threats (eg. Plants protect soil from erosion, filter air, produce oxygen) Total services provided The value of ecosystems is greatly reduced when ecosystems are thrown off balance! Equilibrium and Change O Most natural ecosystems are in a state of equilibrium – relatively stable biotic and abiotic features. O Energy flows through food webs, nutrients are recycled, photosynthesis and cellular respiration are balanced O On a small scale, most ecosystems are in constant change. E.g. a fire breaks out, a tree falls etc. Ecological Succession O Ecological succession – process of establishing and replacing a community following a disturbance. O O Primary succession – occurs on bare rock where there was no previous life O Secondary succession – follows a disturbance that disrupts but does not destroy the community. Ecological Succession O Benefits of succession – mechanism by which ecosystems maintain their long-term sustainability. O Not all disturbances can be repaired through natural succession. Human disturbances often have to repair ecosystems through processes that support natural succession. Textbook question O A Krakatoa eruption destroyed life and left behind volcanic ash. A large chemical spill can also destroy life. How would succession be very different following these two events? What is one way to ensure stability of ecosystems? Biodiversity Biodiversity O variety of life found in an area O Measured by counting the number of species in a specific habitat or ecosystem. This measurement of species is called species richness O In general, species richness tends to be higher close to the equator O Tropical rainforests have the highest biodiversity of any ecosystem. Species at risk O Many of the world’s species are dying out or going extinct. Their habitats are destroyed through deforestation, urban and agricultural expansion, pollution and climate change. Extinction events O Extinction is a natural process. Over thousands of millions of years, some species become extinct while new species arise. O There have been at least 5 major extinction events in the past billion years. Extinction Extinction events are usually caused by a catastrophic event such as an asteroid impact or massive volcanic eruption. Between such rare events, extinction rates are low. Unfortunately, human activity has greatly increased the rate of extinction. Species at risk O Species do not have to be driven to extinction for there to be ecological consequences O In Canada, the status of species is monitored by the Committee on the Status of Endangered Wildlife in Canada. Species at risk O Extirpated – no longer exist in their native area but are still alive elsewhere (eg. Atlantic walrus) O Endangered – species are in imminent danger of going extinct or becoming extirpated. O Threatened – Species likely to become endangered if current trends continue (ie. humpback whale) O Special concern – may become threatened or endangered because of a combination of factors. Endangered Threatened Special concern Population ecology What about us?