Ecosystems and ecology

• This unit explores species, ecosystems, energy flow, food chains, symbiosis, the carbon cycle, habitat destruction (including pollution effects), and conservation.
• The unit is designed to take approximately three weeks.

Defining Ecology Basics

• Ecology studies how living things interact with each other and their physical environment.
• Living things exhibit characteristics known by the acronym MRS GREN: Movement, Reproduction, Sensitivity, Growth, Respiration, Excretion, and Nutrition
• A species is a group of organisms capable of producing fertile offspring, sharing similar structural and behavioral traits.
• Population refers to members of the same species living and interacting in a specific area at the same time.
• Biotic (living) and abiotic (non-living) factors determine population size within an ecosystem.
• Abiotic factors influence the type of ecosystem, the organisms present, and their population sizes (e.g., soil type and climate for kauri trees).
• Biotic factors encompasses interactions between communities in a forest.
• An organism's habitat provides its living place, based on abiotic factors; Pukeko are found in vegetated areas near water with open grasslands.
• An organism's niche is its role in its environment; Pukeko eat grasses, insects, and defend their territory.
• Two species cannot occupy the same niche
• A community involves interactions among all populations within a habitat.
• Ecosystem is the interaction between the abiotic and biotic factors in a given area.

Energy Flow and Food Chains

• All ecosystem energy originates from the Sun.
• Plants conduct photosynthesis by capturing light energy to transform it into a transferable form.
• Photosynthesis equation: Carbon Dioxide + Water + Sunlight = Glucose + Oxygen.
• Animals obtain energy by consuming other organisms and breaking down glucose through cellular respiration for other processes.
• Autotrophs, or producers, carry out photosynthesis and use its products in processes like respiration.
• Consumers obtain energy by feeding on other organisms, and include herbivores, carnivores and omnivores.
• Decomposers break down dead material.
• A food chain illustrates energy transfer from one organism to the next, beginning with a producer, representing energy flow in an ecosystem.
• Energy flow direction is shown using arrows and Plants are the producers in a food web, while animals are described as primary, secondary, or tertiary consumers.
• An animal that eats plants is a primary consumer, an animal that eats herbivores is a secondary consumer, and an animal that eats secondary consumers is a tertiary consumer.
• Trophic (feeding) level is the position of an organism in a food chain.
• Only about 10% of energy is transferred to the next level because organisms use energy for life processes and food chains rarely exceed five trophic levels.

Food Webs

• Few species consume only a single organism for energy; species that do are highly endangered.
• A food web is a network of interconnected food chains, illustrating energy flow through an ecosystem.
• Consumers can occupy multiple trophic levels.

Relationships Between Living Things

• Symbiosis is the relationship between species in a community.
• Mutualism benefits both species: Mistletoe flowers attract birds for pollination and birds feed on nectar.
• Commensalism benefits one species without affecting the other: barnacles benefit from whale habitat.
• Parasitism benefits one species while harming the other: mistletoe harms the host tree by taking nutrients.
• Humans have altered food webs, shifting from diverse farming to monoculture, increasing fertilizer, herbicide, and pesticide use, leading to habitat destruction and pollution

Carbon Cycle

• Carbon is a key component of living organisms.
• Plants obtain carbon from atmospheric carbon dioxide, while animals obtain it from plants and other animals
• The carbon cycle traces carbon movement between the atmosphere and living things.
• Plants use light and carbon dioxide in photosynthesis to produce glucose, which is then used to create starch, cell walls, and proteins.
• Animals digest plant material, absorbing carbon for their tissues.
• Fossilization occurs when carbon in dead organisms is compressed into fossil fuels like oil.
• Respiration uses oxygen to break down glucose into carbon dioxide and water, returning carbon dioxide to the atmosphere as a waste product.
• Decomposition breaks down dead organisms, releasing stored carbon back to the environment for use by producers.
• Combustion of fuels releases carbon dioxide into the atmosphere.

Habitat Destruction

• Smaller human groups had less environmental impact when obtaining food through hunting and gathering, because their demands were lower.
• Agriculture allowed larger human groups by altering the environment, replacing natural plants and animals.
• Increased population size led to agriculture which meant humans changed the environment to suit needs, clearing land for single-species crops
• Ecosystem destruction is caused by the need for area for crops, livestock, extracting natural resources,
• Humans alter food webs, and Deforestation leads to species extinction, soil erosion, flooding, and increased carbon dioxide.

Pollution

• Unregulated activities from population growth and industrialization have increased ecological imbalance.
• Pollution includes contamination by sewage, chemicals, and gases.
• Biodegradable pollutants are broken down by biological agents, like converting kitchen waste into manure by microorganisms.
• Non-biodegradable pollutants cannot be broken down by biological agents (e.g., plastic).
• Air pollutants include carbon particles, Sulphur dioxide, Lead, and CFC's
• Water pollutants include waste water and fertilizers.
• Soil pollutants include polythene, plastic, industrial waste, fertilizers, pesticides, and insecticides.
• Noise pollutants are caused by industries, transportation, entertainment, and construction.

Eutrophication

• Eutrophication begins with excessive nutrients from fertilizers washing into water bodies.
• Increased nutrients cause algae to bloom, blocking sunlight to other plants, which die.
• Decomposers break down dead plants, using up oxygen and resulting in the death of all other organisms in the water.
• Eutrophication causes are agriculture and meat/dairy processing in New Zealand.

Conservation

• A sustainable resource is one that can be replenished as quickly as it is used.
• Raw materials like metal ores and fossil fuels are non-renewable and need alternative energy sources.
• Biological Diversity is the different populations present in an ecosystem.
• High biodiversity is better than low biodiversity
• Biodiversity underpins medicine because medicines are derived from plants and animals.
• Biodiversity important for food because 35 plants provide 95% human food supply, genetic resources as wild relatives can provide disease and immunity genes to crops.
• Keystone species maintains an ecosystem like Snapper and kelp forests in New Zealand.
• Humans must have responsibility to ensure long term survivability of species
• Conservation maintains biodiversity.
• Declining biodiversity can result from habitat destruction, alien species, over-harvesting, international trade, pollution, and climate change.
• Efforts reduce extinction by protecting vulnerable species and habitats.
• Zoos conserve through captive breeding and education, even though it is often controversial.
• National Parks protect native species and habitats, while Marine Reserves protect areas from fishing.