Interactions between species and their environment Ecosystem Dynamics

Overview Questions What are the abiotic and biotic components of an ecosystem? How is life on Earth sustained? How can the health of an ecosystem be evaluated? How have humans impacted ecosystems?

Ecosystem Components BIOTIC – living Plants (producers) Animals (consumers) Bacteria Fungi Protists ABIOTIC – non living Water (dissolved nutrients, p. H, salinity, dissolved oxygen, temperature) Soil (p. H, nutrient availability, composition, temperature, humidity, light intensity, wind etc. ) Climate (precipitation, temperature)

Ecosystem Structure Individual Organism Population Community Ecosystem Biosphere

Individual Organisms are grouped into different species based on certain characteristics. Black Footed Ferret (Endangered species) Photo credit: Ryan Hagerty; U. S. Fish and Wildlife Service

Population Individuals of the same species living together in an area. Photo credit by Kevin Bell; U. S. Fish and Wildlife Service

Community All the various species (plant and animal) interacting in a particular area. Photo Credit: George Gentry: U. S. Fish and Wildlife Service

Ecosystem An ecosystem is a biological environment consisting of all the organisms (biotic) biotic in a particular space, as well as all the nonliving (abiotic), abiotic physical components of the environment with which the organisms interact, such as air, soil, water and sunlight. Photo Credit: U. S. Fish and Wildlife Service

Biosphere The global ecological system incorporating all ecosystems plus the hydrosphere, lithosphere, and atmosphere. Our biosphere is the global sum of all ecosystems. It can also be called the zone of life on Earth.

Species Diversity Biological communities differ in the number and types of species. Species diversity- the number of different species a community contains. Species richness

Factors Influencing Species Diversity

Intra-specific Competition: Competition for resources between individuals of the same species. Photo credit: Dave Menke and Christopher Serbeck; U. S. Fish & Wildlife Service

Inter-specific Competition: Competition for resources between different species living in the same community. Photo credit: Dave Menke and Christopher Serbeck; U. S. Fish & Wildlife Service

How can the health of an ecosystem be evaluated? Indicator Species – a species whose presence, absence, or abundance can be used to assess the health (presence of pollutants, etc. ) of an ecosystem. Example: Frogs are a good indicator species because their life cycle includes phases in water and land. Keystone Species – a species which plays a crucial role in maintaining the structure of the ecosystem despite its abundance. An ecosystem may experience a dramatic change if this species is removed or negatively impacted. Example: sea otters , sea stars, jaguars, alligators

Native Species A species indigenous to a given area. Example: whooping crane; migratory crane- native to Texas. Also an endangered species due to habitat loss. Photo credit: U. S. Fish and Wildlife Service

Invasive Species A non-native species of plant or animal whose presence negatively impacts the balance of the ecosystem community. These species often are purposely or accidentally introduced by humans. Example: European Starling – introduced to the U. S. as a plan to have all birds mentioned in the works of Shakespeare. Destroys crops and competes with native species. Photo Credit: Dave Menke; U. S. Fish and Wildlife Service

Some Characteristics of Invasive Species • Rapid reproductive rate • Rapid growth • Tolerance to wide range of abiotic factors • Lack of natural predators or unusually effective defense mechanisms • Compete aggressively for resources • Estimated cost in the U. S. for damage and control of invasive species is $100 billion per year. Photo credit: Kudzu; invasive Japanese non-native vine. Scott Ehart ( public domain)

Carrying capacity and Limiting factors Carrying capacity – the maximum number of of a species that can be indefinitely sustained by a specific ecosystem given the resources available. Limiting factor(s) – a population can be limited by the availability of matter and energy resources. E. g. food, water, space, temperature, and p. H.

Range of Tolerance A given population will thrive within a particular range of abiotic factors. Outside of that optimal range will be found less and less individuals of a population. Example: p. H range of tolerance for a species of fish in an aquatic ecosystem is between 6. 9 and 7. 5. p. H’s less than 6. 9 and greater than 7. 5 will have less individuals able to survive.

Human impacts on an Ecosystem H - “H. I. P. P. O” Habitat destruction, fragmentation, or degradation I - Invasive species P Pollution P - Population increase of humans O - Overhunting, or overharvesting