Ecosystems: What they are Chapter 2

1. Ecosystems: What they areChapter 2 • When we talk about the environment, we are often referring to a specific Ecosystem. • This chapter is mostly about definitions. We’ll be defining a number of terms related to ecosystems, and then discuss the various components (with more definitions  )

2. Ecosystems • They start with the living and non-living parts- the biotic and abiotic components • Biotic community: plant, animal, and microbial (not that they really know they’re a community!) • Species: Similar enough to breed

3. Population: Interbreeding members of a species- they are together in time and space (except bacteria)Association: Some species (particularly plants) are found in definite combinations. • When you put them together, you get an ECOSYSTEM: The BIOTIC community, together with the abiotic factors; includes all the interactions among the members of the bioltic community, and between the biotic community and the abiotic factors, within an explicit unit of space. • Forests, grasslands, wetlands, marshes, ponds, coral reefs are all ecosystems. • Ecosystems can blend into one another (2-3)- the blended areas are ecotones.

4. Biome: Major ecosystems such as tropical forests or grasslands. • Biosphere: All the ecosystems on the planet.

5. Structure of Ecosystems • Trophic categories: Producers and consumers. • Producers are autotrophs (2-5), that turn light, CO2, and water (inorganic compounds) into glucose and other organic compounds. Other inorganics, (K, PO4-3, NO3- etc.) are also incorporated into living things. Think PLANTS!

6. Structure of Ecosystems • Consumers are heterotrophs and eat the producers. • ANIMALS • Primary consumers: COWS, other herbivores. • Secondary consumers: PEOPLE, carnivores • Parasites and pathogen feed on all types. • Detritus feeders and decomposers • 2-11

7. Food chains, webs, trophic levels • Fig’s 2-12,13 • Only 10% of the biomass from each level is transferred to the next trophic level.

8. Other relationships • Mutualistic relationships- lichens, bees; they actually abound in nature! • Competitive relationships- individuals within a species may compete, but each organism often has its own habitat and niche. Habitat is where an organism lives; its niche is its job • Plants often compete directly for space. • Competitive exclusion principle:

9. Abiotic Factors • Climate: rainfall and temperature are major players. • Major Biomes: Table 2-3 • Other factors: salt, pH, animal effects, human effects (MAJOR) • Fig. 2-18: many, many factors can be limiting: temp., nutrients, water, etc.

10. Things to know • Major definitions: Table 2-2, except association and landscape • Producers, consumers (primary, secondary), detrivores and decomposers, organic, inorganic, autotroph, heterotroph • Major Biomes, particularly the ones around here. • Food chain, food web, trophic level • Mutualistic, competitive relationships (describe and give examples of these) • Competitive exclusion principle- describe and give examples of. • Abiotic factors- give examples, and what is meant by optimum, zones of stress, and limits of tolerance.