Principles of Ecology Chapter 13 Sections 2-7

Biotic and Abiotic Factors Ecosystems are made of living and nonliving things. Biotic factors are living things. Ex: plants, animals, fungi, bacteria Each one plays an important role in the ecosystem. Abiotic factors are nonliving things. Ex: moisture, temperature, wind, sunlight, and soil The balance of these factors determines which living things can survive in certain environments. Ecosystems are always undergoing change. We have cyclic changes that force ecosystems into a balance called approximate equilibrium.

Biotic and Abiotic Factors In your own notes write down as many abiotic and biotic factors as you can for a marine ecosystem.

Biotic and Abiotic Factors Humans also rely on abiotic factors. This means that we are affected by any that take place in an ecosystem. Biodiversity is the assortment, or variety, of living things in an ecosystem. Certain parts of the world have unusually large amounts of biodiversity. Ex: Tropical rainforest Hotspots= areas that are rich in biodiversity but are in danger because of human activities.

Biotic and Abiotic Factors What do you think happens if we start losing biodiversity in ecosystems? The smallest changes in biotic or abiotic factors can have many different effects on the entire ecosystem. The loss of a species can effect the entire ecosystem Keystone species is a species that has an unusually large effect on its ecosystem. Ex: Beavers change free-flowing stream habitats into ponds, wetlands, and meadows by building their dams.

Energy in Ecosystems All organisms have to have a source of energy in order to survive. Producers aka Autotrophs are organisms that get their energy from nonliving resources = they make their own food. Consumers aka Heterotrophs are organisms that get their energy by eating other living or once-living resources like plants and animals. All ecosystems rely on producers because they are the basis for the ecosystem’s energy. Gray wolves eat Elk and Moose eat plants (producers) All consumers are some how connected to producers Producers rely on the sun for energy What happens if we take out the producers?

Energy in Ecosystems Green plants, cyanobacteria, and some protists use photosynthesis to produce energy.

Energy in Ecosystems What about producers that are deep down in the ocean? Chemosynthesis is the process by which an organism forms carbohydrates using chemicals, rather than light, as an energy source. A series of reactions change the chemicals into usable energy.

Food Chains and Food Webs The easiest way to see how energy flows through an ecosystem is through a food chain. A food chain is a sequence that links to species by their feeding relationships.

Food Chains and Food Webs Herbivores are organisms that eat only plants. Carnivores are organisms that eat only animals. Omnivores are organisms that eat both plants and animals. Detritivores are organisms that eat detritus, or dead organic matter. Decomposers are detritivores that break down organic matter into simpler compounds. They are very important because they return vital nutrients back into the environment. Specialists are consumers that feed on one specific organism or on a very small number of organisms. Example: Florida Snail Kite that feeds on Apple Snails.

Food Chains and Food Webs Generalists are consumers that have a varying diet. Eats

Food Chains and Food Webs Trophic levels are the levels of nourishment in a food chain. Energy flows up from the lowest trophic level (producers) to the highest. Primary consumers herbivores because they are the 1st consumer above the producer level. Secondary consumers are carnivores that eat the herbivores. Tertiary consumers are carnivore that eat secondary consumers. Where would humans fit in?

Food Chains and Food Webs Some generalists might be apart of more than one food chain. We use food webs to help us see the bigger picture. Food webs are models that show us the network of feeding relationships and the flow of energy within and sometimes beyond an ecosystem. In each link of a food web, some energy is stored in an organism and some energy is lost to the environment.

Cycling of Matter Matter never disappears, it just changes or transforms. The hydrologic cycle aka the water cycle is the circular pathway of water on Earth from the atmosphere, to the surface, below ground, and back. Many elements are essential to the structure and function of an organism. Example: Oxygen and hydrogen make water, which is vital to us. Carbon, Nitrogen, Phosphorus, and Sulfur are also important. All of these elements cycle through ecosystems just like water does. Biogeochemical cycle is the movement of a particular chemical through biological (living) and geological (nonliving) parts of an ecosystem.

Cycling of Matter Oxygen is a byproduct of photosynthesis. Plants give it off, humans and animals inhale it and release it as carbon dioxide.

Cycling of Matter Carbon is considered the building block of life. It exists in nearly everything. Carbon is a part of the biotic and abiotic world. It can be found in all states of matter: Carbon dioxide is a gas that can be found in the atmosphere. Bicarbonate is dissolved in water Fossil fuels Carbonate rocks like limestone Dead organic matter in the soil Carbon moves through the biotic world as one organism eats another.

Cycling of Matter 78 percent of the Earth’s atmosphere is made of nitrogen gas. Because most organisms can’t take straight nitrogen (we get it in the form of ions) most of the nitrogen cycle happens underground. Certain kinds of bacteria convert gaseous nitrogen into ammonia through a process called nitrogen fixation. Cyanobacteria do this in the ocean On land, some do it in something called a nodule which is in the roots of plants. Some live freely in the soil Ammonia becomes ammonium with the addition of hydrogen. Ammonium gets used by nitrifying bacteria as energy and turn it into nitrate.

Cycling of Matter Nitrate that get released by the soil are absorbed by plants, which covert them into things like amino acids and proteins. The nitrogen will continue along the cycle when animals eat plants or animal matter. Decomposers break down animal excretions or dead animal and plant matter, nitrogen is returned to the soil as ammonium, in a process called ammonification. Denitrifying bacteria use nitrate as an oxygen source and release nitrogen gas into the atmosphere. Lightning can break apart nitrogen in the atmosphere by atmospheric fixation. It turns into Nitrogen oxide which with rain water will turn into nitrates.

Pyramid Models The sun provides energy for all ecosystems. The energy from photosynthesis flows up through the food chain. Along the way though some of the energy is lost to the environment, mainly as heat. Herbivores eat the plants, but burn some of the energy in the process. Same goes for the carnivores. Each meal we eat is packed with energy in the form of fats, carbohydrates, and proteins. We use all of these in order for our body to function, and what we don’t use we excrete.

Pyramid Models Biomass is a measure of the total dry mass of organisms in a given area. When a consumer takes the biomass of a producer into its own biomass, a lot of energy gets lost along the way as heat and waste. For example: A plant traps energy from photosynthesis. A prairie dog eats the grass. He uses some of the energy to grow. The rest is used as fuel or doesn’t get digested. We can lose as much as 90 percent of the energy so we really only transfer about 10 percent from one trophic level to another. The longer the food chain, the more energy that is lost overall.

Pyramid Models An energy pyramid is a diagram that compares energy used by producers, primary consumers, and other trophic levels.

Pyramid Models A biomass pyramid is a diagram that compares the biomass of different trophic levels within an ecosystem. It provides a picture of the mass of producers needed to support primary consumers, the mass of primary consumers required to support secondary consumers, etc.

Pyramid Models A pyramid of numbers shows the numbers of individual organisms at each trophic level in the ecosystem.