Ch. 4 & 5: Ecosystems are Dynamic & Ecosystems and Matter Cycling Flashcards
What is ecological succession and what’s a disturbance?
Ecological succession - when a new community of species overtime replace the previous due to changing conditions
Disturbance - either a natural or human-caused event that interrupts a ecological succession (wildfires, flood, avalanche, etc)
What are the basic types of successions?
Primary succession - colonization of a previously unvegetated surface; maybe it was caused by something like glacier retreats that removes all traces of vegetation from the previous ecosystem; little to no soil exists
- the first species to occupy these unvegetated surfaces are primary colonizers, and they have to be able to withstand varying temps, limited water availability and limited nutrients, so they adapt w/ methods that help them break down materials, trap water, etc. to survive (ex/lichens)
Secondary succession - colonization of surfaces where soil or some vegetation is present (abandoned fields, clear cut forests); it’s faster for these kinds of areas to reach advanced successional stages because it already had some vegetation so it had a ‘head start’
Why are climax communities/stages in ecosystems so rare?
Because disturbances (man-made or natural) are a lot more common, so they prevent all the elements in an environment from healthy growth
What is climatic climax & edaphic climax?
climatic climax - climax (meaning stable, healthy) vegetation that’s strongly influenced by climate
Edaphic climax - soil characteristics are the most important in community composition
What is the intermediate disturbance hypothesis?
It’s the hypothesis that moderately disturbed ecosystems maintain higher levels of diversity compared to low or high disturbed ecosystems
What are invasive alien species?
They are species that are found outside their normal range and habitat; they are invasive because they tend multiply quickly, out-compete other native species, and change native habitats (ex/ Asian carp fish was introduced to the U.S for aquaculture, but now they dominate freshwater ecosystems due to their massive appetite)
-These kind of species are one of the leading causes to biodiversity loss
Are all alien species invasive?
No, some alien species can integrate naturally not not cause harm to the ecosystem
ex/ Honeybees were originally native to Europe, Africa, and Asia, but spread worldwide helping with pollination and honey production
ex/ Tomatoes were originally from South America but now is grown globally w/ out harming ecosystems
What is polar amplification?
It’s the phenomenon caused by climate change that causes temps in North poler regions to rise faster than the global avg temps
-How it works is that, warmer air from lower latitudes moves toward the poles, and as ice starts to melt it exposes darker ocean or land and they absorb more sunlight leading to more warming
-It causes big consequences like faster ice melt, which could raise sea levels, and it ruins habitat meant for species adapted to the cold like polar bears, and disrupts Artic food webs
What’s the difference between density-dependent organisms and density-independent organisms? What’s shape are their growth curves?
Density-dependent organisms - as the population density of organisms increases, the rate of growth decreases (ex/ fish; when the density of fish in an area changes, so does the growth rate of the fish population); these kind of organisms show a s-shaped growth curve
Density-independent organisms - as pop density increases, rate of growth increases also, following a j-shaped growth curve, but at some point the population reaches the environmental resistance (factors that drive carry capacity) , which causes it to fall back down to the carrying capacity (Zebra mussel; their food supply was exhausted)
What is biotic potential? What are r and k strategies?
Biotic potential - the maximum rate that species could increase at if there was no environmental resistance
- r and k strategies are the diff types reproductive strategies that organisms have
r-strategy (quantity over quality) - this strategy focuses on producing large numbers of offspring but invest little parental energy in their upbringing, because most energy has been spent on reproduction (ex/ zebra mussel); these species usually don’t long too long
k-strategy (quality over quantity) - produce few offspring but put most energy into parenting them so they reach maturity; these species tend to live longer and are larger (ex/ larger mammals like humans)
What are the 4 kinds of major compounds that make up living organisms?
Carbohydrates, fats, protein, nucleic acids
What are the 6 main nutrients that make up about 97% of organic mass?
Carbon, phosphorous, hydrogen, nitrogen, oxygen, and Sulphur
Compare gaseous cycles and sedimentary cycles. Which is faster and why?
These cycles can be classified by the main source of their matter
-Gaseous cycles - are faster because they have most of their matter in the atmosphere (nitrogen cycle)
-Sedimentary cycles - are slower because most of its matter in held in the lithosphere (phosphorous & sulphur cycles)
Explain sedimentary cycles
-These cycles moves material from the lithosphere to the hydrosphere, then back to the lithosphere; some involve a gaseous phase and some don’t
-these cycles depend on geological processes over long periods of time to complete the cycle, but human action and activity speeds them up, resulting in environmental problems
Explain the nutrient Phosphorous
-It’s a macronutrient needed for metabolic energy use; due to it being in such high biological demand it’s rare find on Earth’s surface and replenishment rates through soil and weathering availability is limited
-Phosphorous is also usually the dominant limiting factor (most important factor that restricts the most growth, and survival) in freshwater systems and for plant growth in soil (ex/ rocks in Earth’s crust are main reservoirs of Phosphorous, and it’s also highly found in animal bones and wastes)
- soil acidity affects its availability; if pH is below 5.5, then it reacts w/ aluminum and iron to create compounds that can’t be dissolved. Above PH of 7, same thing occurs but it joins w/ calcium
- When breaking down in soil, P is either absorbed again by plants or transported away by water into the ocean
-also ends up in high productivity estuaries and shallow productive coastal areas
Explain the nutrient Sulphur. How is climate change affecting the cycle?
It’s a needed component for all life and a building component for proteins; it, like phosphorous, is a sedimentary cycle
-Sulphur is mainly found in sedimentary rocks but also differs from P in some ways: it has a atmospheric component hence better recyclable potential, it’s not rarely limiting, and it has strong dependencies on microbial activity
-in order to be absorbed by plants it needs to be transformed into sulphates
-Climate change is affecting this cycle due the rising temps of the north and it causes drying peat beds to become re-wet, which releases 3-4x as much sulphur dioxide (SO2)
Explain the nutrient Nitrogen. How does human activities affect it?
- Nitrogen is a tasteless and odorless gas that is needed for all organisms of life, and it makes up 78% of the atmosphere
-It cycles between the lithosphere and atmosphere, and most animals obtain it from the soil (lithosphere) as nitrates
-This transformation from nitrogen gas to nitrates is called nitrogen fixation, and it involves bacteria changing nitrogen in the soil to various forms available for plants; its a mutualistic relationship because bacteria converts the nitrogen for plants and in return they get photosynthesis products
-Most physical nitrogen comes from breakdown of biomass by decomposing organisms; its quickly depleted from soil and becomes a limiting factor for plant growth - One human activity that affects the use of nitrate and ammonia as fertilizer, which, because of its high solubility, could get into runoff water
Explain the nutrient Carbon
Carbon dioxide only takes about 0.03% of the atmosphere, but its the main reservoir for the carbon that’s the building block of life
-Plants take up carbon dioxide directly from the atmosphere for photosynthesis process; its incorporated in biomass and passed along the food chain
-respiration by decomposers changes the carbon in dead organisms back into CO2, which re-enters the atmosphere
Explain the hydrological cycle
Water occurs in a fixed supply that cycles between various reservoirs
-The ocean is largest reservoir (97%); the rest is held in polar ice caps and a small amount in freshwater
-Gravity moves water (through rain) down to the soil, which it penetrates through to reach the water table (area containing water between soil particles). This is called groundwater
-Global temp changes like melting ice caps and climate change are changing residence times (length of time it takes for something to stay in Earth’s reservoirs) as a result
What is eutrophication?
The process of nutrient enrichment (mainly phosphorous & nitrogen) of water bodies, leading to greater productivity; this causes increased growth of aquatic plants especially phytoplankton
-plants lower down don’t get much sunlight and therefore, produce less oxygen, but oxygen produced by phytoplankton is usually on the water surface and re-enters atmosphere; dead phytoplankton filters down where its eaten by oxygen-demanding decomposers, leading to oxygen depletion
-This process used be just a problem of smaller bodies, but now its increased to entire areas of oceans, and they become so oxygen deficient, they’re called ‘dead zones’
What are the main sources contributing to cultural eutrophication?
-Runoff from fertilizers and feedlots w/ P & N
-Discharges of detergents w/ P, untreated sewage w/ N & P, and primary and secondary treated sewage w/ N & P
-emissions from internal combustion engines (use fuel and oxygen to make energy) w/ dissolved nitrogen oxides
-
What is acid deposition and what causes it?
-It’s chemicals that release hydrogen ions when dissolved in water
-acidity is a measure of the concentration of hydrogen ions in a solution, w/ a PH scale from 0 - 14
-acid deposition comes out in ways of rain, snowfall, fog, etc.
-What causes it is the increased acidity due to the human inferences of the Sulphur and Phosphorous cycles, from the largest sources of heating & melting of Sulphur-rich metal ores, and the burning of fossil fuels for energy
