Unit 3: 3.1.2: Effects of Cycles on Ecosystems

Which of the following statements about the phosphorus cycle is true? A) In living organisms, phosphorus can be found in nucleic acids. B) Phosphorus in aquatic ecosystems is only found in sediment. C) Elevated levels of phosphorus in aquatic ecosystems is always beneficial. D) The soil plays no part in the phosphorus cycle.

A) In living organisms, phosphorus can be found in nucleic acids.

Plants in the desert __________. A) effectively conserve and retain water B) have high levels of transpiration C) release 50-80% of water back into the ecosystem D) make their own precipitation

A) effectively conserve and retain water

Which of the following processes play a role in introducing both water and carbon in the earth's cycles? A) photosynthesis and respiration B) condensation and nitrogen fixation C) burning of fossil fuels and forest fires D) desertification and condensation

A) photosynthesis and respiration

Hibernation is __________. A) an example of an abiotic cycle B) triggered by changes in the weather C) caused only by biotic factors D) triggered by breeding patterns

B) triggered by changes in the weather

Where do animals obtain carbon? A) the atmosphere B) plant and animal consumption C) the soil D) photosynthesis

B) triggered by changes in the weather

Which of the following is not a way in which carbon is introduced into the atmosphere? A) forest fires B) respiration C) photosynthesis D) burning of fossil fuels

C) photosynthesis

Plants in the rainforest __________. A) effectively conserve and retain water B) have low levels of transpiration C) release 50-80% of their water back into the ecosystem D) are adapted to conditions of drought

C) release 50-80% of their water back into the ecosystem

Phosphorus is contained in __________. A) living organisms B) soil C) water D) all of the above

D) all of the above

What happens to the carbon in living organisms when they die? A) It is incorporated into other organisms. B) It is released back into the atmosphere. C) It is incorporated into the soil. D) all of the above

D) all of the above

Hibernation, migration, and breeding can be attributed in part to __________. A) fluctuations in the carbon cycle B) fluctuations in the nitrogen cycle C) fluctuations in the phosphorus cycle D) fluctuations in seasons

D) fluctuations in seasons

section 2

It would be hard to deny the fact that human beings have caused significant changes and damage to our planet over the last 100 years. With the beginning of the Industrial Revolution, we have been emitting greenhouse gases into our atmosphere, causing climate change. Well, now that we see these problems that we've caused, we're trying to figure out ways to solve those. And we have some pretty good ideas. But when we talk about these really large scale ways of solving the problem such as global warming, this is called geoengineering, and this is just one thing we're going to talk about in this section. Effects of Cycles on Ecosystems Section Two. We've already explained how fluctuations in abiotic cycles influence populations. Now we're going to describe the movement of carbon compounds through a food web and describe the effects of abiotic cycles on local ecosystems. So abiotic factors in ecosystems must be in balance for the ecosystem to be healthy. So if we don't have these abiotic factors in balance, we're going to have some serious problems with our ecosystems. So water, soil, nutrients, energy, and atmospheric gases are all things that we would include in these abiotic cycles. These are all dynamic systems. They don't stay the same. They're constantly changing, and things are always being recycled. So this material is costly moving through the ecosystem, and they need to replace what is being used. As we mentioned before, if we did not replace and recycle the stuff that we use, we would simply run out of material to live and we would not survive. So it's a vital component of survival on our planet. So what are some of the effects of abiotic cycles? Well, let's look at an example of one of the abiotic cycles. The example is carbon, the carbon cycle. Now carbon is abundant throughout earth's systems. It exists in oceans, air, rocks, soil, and all living matter. And is constantly being used and replaced. So here's a diagram that shows the carbon cycle. The carbon is always being recycled throughout our entire ecosystem. As we know, we would simply run out, we would not survive if it didn't. So some of the main steps that I'd like to mention here. We have carbon from the atmosphere gets taken in by plants. So we have our carbon in the form of CO2 in the atmosphere that gets taken in by our plants. The plants use that for photosynthesis and they use it to create sugar. So that carbon is now being stored in the form of sugar in the plant. So now animals can gain that carbon by eating those plants. And these animals use that carbon, or the bonds that are being held in those sugar molecules, for energy. We then can release that carbon back into the atmosphere in the form of CO2 again, or we can store it in our bodies. If we store it in our bodies, we will someday die, and that carbon will then end up in the soil. Now certain types of organisms over long periods of time, if they are deceased and they're buried underground and put under just the right circumstances, they can become fossil fuels such as oil and coal. Now this coal can remain buried for millions and millions of years, and when finally humans dig it up and burn it, that CO2 is once again released back into the atmosphere. So there are a lot of different ways that this carbon can move from place to place on our planet. The carbon can also move from the atmosphere to the oceans. So this carbon is always moving around. It's always going to be moving and transferring from one form to the other. And all organisms are going to require that carbon for different uses. The water cycle is another really important cycle that is an abiotic cycle, or it's non-living. So an example of how the water cycle works in two different areas of the world would be the rainforest, which has high levels of transpiration. Now remember, transpiration is the way that water evaporates from the pores in the leaf of a plant. So as it comes out of those leaves on the plant, it goes back into the atmosphere. If you have a lot of plants that are performing a lot of transpiration, you're going to getting a lot of water vapor in the atmosphere above that forest. And eventually when that concentration gets high enough, it's going to create clouds and it's going to fall back down as precipitation. So in effect, the rainforests actually kind of create their own rain. They release 50% to 80% of the moisture back into their ecosystem. So although they require a lot of water to grow, they only use it for a short period of time and then they re-release it back into the atmosphere. So plants of the rainforest have adapted to large amounts of water. It's because there's so much water available, so they can use all of this water to help them grow. They simply re-release it back into the atmosphere, and then it's going to rain back down on them again. So if we compare the rainforest to a place like the desert, the desert's going to have quite a different approach to that. The desert has low levels of precipitation, as you know, and it does not create its own precipitation. Rather, it relies on precipitation from the weather patterns that pass over it and through it. So the plants here, rather than performing a lot of transpiration, they hold onto that water. They're adapted to drought conditions. They conserve their water, because if they didn't, they simply wouldn't survive in such a drought area. So we mentioned geoengineering. Geoengineering are ways that we're trying to figure out how to solve some of the problems that we've caused with our environment. So we have something called greenhouse and solar forcing. The idea of a sun shade, or blocking some of the sunlight from coming into the earth's atmosphere is something that's been thrown out there. Now with this idea, they think that if we can block some of that sun with some sort of reflector or shield, we can keep some of that energy from entering our atmosphere and we can keep our temperatures from rising. It's an interesting idea. So it might reduce the amount of sunlight that's actually going to hit the earth, thus slow down global warming. We also have the idea of actually removing carbon dioxide from the atmosphere. We could take the carbon dioxide, remove them, and store them in certain areas, such as deep underground or in the bottom of the ocean. So by removing the CO2 or the carbon dioxide from our atmosphere, we're actually reducing the amount greenhouse gases, so we're going to slow or stop the advance of global warming. We also have an idea of cloud seeding. Now, cloud seeding is something that farmers can use. They spray a certain sort of particle into the atmosphere, and it goes up into the clouds and supposedly causes it to rain or drop that rain more quickly. So if you have certain areas of the country that are experiencing drought and we require those areas for agriculture in our country, this cloud seeding might be able to help us to regulate our rainfall and get the rain where we need it, when we need it on our earth. However, all of these things do seem to be pretty good ideas, studies have indicated that greenhouse and solar forcing may in fact slow down the global water cycle. So if we do put something into the atmosphere that blocks out some of our sun, it may actually slow down our water cycle and decrease our rainfall, which would have a really detrimental effect on many other parts of our ecosystems. So I'd say, once again, we've accomplished our mission. Hibernation, migration, and breeding of populations are often influenced by abiotic cycle in ecosystems. Ecosystems are dynamic and constantly recycle matter to maintain a balance. And abiotic factors like the water cycle help determine the characteristics of an ecosystem.

section 1

Lately, we've been talking about a lot of different cycles that we have on our planet. More specifically, we've been talking about abiotic cycles. Now if you remember, abiotic refers to the fact that they're not living. So things like the carbon cycle, the nitrogen cycle, and the phosphorus cycle are all abiotic cycles. It's important to understand that these cycles aren't always the same levels. They don't cycle perfectly even at all times. They do fluctuate. And these fluctuations can affect organisms, their populations, and how they survive. That's what we're going to talk about in this section. Effects of Cycles on Ecosystems, Section One. We're going to explain how fluctuations in abiotic cycles influence populations. And looking ahead, we'll describe the movement of carbon compounds through a food web and describe the effects of abiotic cycles on local ecosystems. So before we talk about how these fluctuations affect populations of organisms, it's important to understand that we have three different abiotic layers on our earth. These three abiotic layers are the atmosphere, which is the protective layer of gases that surrounds the earth, as you know. The hydrosphere, which is earth's water in all of its forms, and the geosphere, which is earth's land in all of its forms. It's important to understand that these things interact with each other. We have a lot of weather that takes place in our atmosphere. So evaporation, precipitation, all that takes place in our atmosphere. We also have a lot of erosion that takes place because of water running on our ground. So the hydrosphere and the geosphere would be interacting with one another. So all of these three areas-- the atmosphere, hydrosphere, and geosphere, the three abiotic layers-- interact with one another. And it's very important that they interact with one another for our survival. So abiotic cycles. These cycles are crucial to every living organism on earth. The balance of abiotic factors is vital for a healthy ecosystem. The different types of abiotic cycles are, as we've talked about in the past, the water, the phosphorous, carbon, and nitrogen cycles. We also have wind and ocean currents, which could be considered abiotic cycles because they are cycles and they are non-living All of the elements in the world are always going to be recycled and reused. Remember, if we didn't have this recycling process taking place, we would not be able to survive. So how do cycles and populations work together? Well, another example of an abiotic cycle would be the seasons of our year. We have winter, we have summer, we have spring, we have fall. Those are all a very regular course that we go throughout the year. So migration is often caused when our seasons come around. So populations are going to have to move to a certain area-- maybe because there's too much competition, or maybe because the weather simply is unbearable and they can't survive there. They're going to also go to different areas of the world to breed. Some species of whales actually migrate several thousand miles just so they can breed and reproduce. Hibernation is also caused when these organisms, such as bears, need to go and lay low for the winter season when there's not as much food available on a regular basis. So things like hibernation are often triggered by changes in the weather-- which is abiotic-- 00:03:27competition for resources, which can be abiotic, but is often biotic, such as food. So our cycles in populations, things like the phosphorus cycle. Phosphorus is contained in living organisms, and it's required to make things such as nucleic acids, which is required for us to make DNA. We could also have our phosphorus in soil and water. The environmental impacts of phosphorus can be positive and negative. We've talked about how phosphorus is required for all of us to survive. We need it to make things like DNA. If we didn't have it, we simply would not be here today. But just as with everything, too much of something can be bad. When we have a lot of phosphorus, it sinks to the bottom of some bodies of water and it collects. And we can see increased or decreased growth of the organisms in those areas. Lake Champlain is an example where we have too much phosphorus and the balance of this lake has been disrupted, or disturbed. When we have too much phosphorus, we actually can receive algal blooms. When we have these algal blooms, which we talked about before, we have a large growth of these microscopic plants. When these microscopic plants begin to die, they are then consumed by other organisms which use up all of the oxygen in the water and can cause all of the other organisms to, consequently, actually suffocate. So looking at our science. When we study things like hydrobionts, or things that live in the water, such as fish, amphibian larvae, or algae, or rotifers, which are kind of microscopic to almost microscopic organisms living in pond water and things like that, we'll see that fluctuations in abiotic factors actually improve the growth in energy metabolism of these organisms, the physiological state of these organisms, their viability or their ability to reproduce, and their tolerance of changing in their ecosystem. So fluctuations of these abiotic factors, if they are too great, can be very detrimental to these organisms. But it also can help them to improve their condition. So thinking ahead to the next section. Our bodies need to be able to break down the food we eat into a usable form to sustain our life. So how does an ecosystem break down materials in its environment into usable forms?