Video 6  Ecosystem Ecology
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Video 6 Ecosystem Ecology


hi ape students welcome to AP environmental science video number six it is on ecosystem ecology now we need to understand the levels of organization within an ecosystem so your first level is in the organism one alligator then you have a population of alligator then you have a community which now includes a bunch of different organisms the ecosystem now includes the abiotic which are all the nonliving things in the ecosystem so the water the air those sorts of things and then the biome is the large region of the same kind of climate and animal plant features now we have one more level that is higher than the biome and that is the biosphere and that includes all of the earth itself now some limiting factors of populations we have our carrying capacity this is the greatest number of individuals a population can can contain sustain so when you go over here we see we have this slow growth then we hit exponential growth also known as the J shaped curve and then once we hit our cake carrying capacity we have hit this kind of s shape which is called logistic growth on so your carrying capacity is maybe we ran out of enough water for everyone so now our population has leveled off now what stage is the human population in we are still in this J shaped curve the growing exponentially we really don’t know what the carrying capacity of the human population could be so some types of limiting factors what can limit your population and make it hit carrying capacity there are some dissident factors things that depend on your population size like food water and shelter disease that sort of thing if there’s not very many individuals disease can’t spread very far density independent factors are temperature droughts floods pollution these are things that the population size does that matter it’s still going to be affected the same way so if you have a hundred organisms versus one organism a drought is going to have the same impact on those organisms so looking at these different factors we have already used these terms a little bit but just make sure you understand them get your definitions so ecosystems consist of abiotic which are your nonliving factors things like the Sun the wind the temperature pH dissolved oxygen and then there’s also live living factors which are your biotic components the plants the animals bacteria all those sorts of things so some different organisms and their specific roles kind of in an environment so you have your Shiki zone species this is an organism that has an unusually large effect on the ecosystem things like wolves alligators elephants you should be able to give some examples beavers are also keystone species so the way I like to think about this is think about it as an ark and your keystone species it’s kind of that middle piece of the Ark and if you take that apart or you take that off the entire Ark is going to collapse um so that is kind of how your keystone species impacts the ecosystem indicator species Service warnings to damage like pollution and things like that on they tend to be insects amphibians on looking at water quality we look at a little macro invertebrates things like the water penny the leech organisms like that um thank the canary in the coalmine so when people used to go mining for coal they would bring a canary in there and if the bird died then you knew that something was going on and the people should get out as well so that’s kind of what’s happening with indicator species they tell us that something is wrong in an ecosystem so looking at the different roles that species play in their environment this is called a niche or a niche and then nice partitioning is the process by which competing species use the environment a little bit differently so that they can coexist and kind of your classic example is the Warblers so these are all different kinds of birds down here there’s actually five different species of Warbler and each one of them uses a different part of the tree so that they’re not interfering with the others ability to survive one may use the bottom one may feed at the middle one may feed at the top so this will be an example of niche partitioning when we look at our producers and our consumers in an ecosystem we need to understand a little bit the chemistry behind it so producers how are they actually providing energy in our ecosystem where they’re doing this by photosynthesis this is a very important equation so please make sure you get it and you write it down you do need to know the equation for photosynthesis memorize it one way that you can remember it not necessarily the best example but it is kind of good if you can remember these numbers 666 like I said not exactly the best thing but people can remember that it is 6 co2 6 h2o glucose and then 602 so that is what plants are producing and then we are taking in that glucose and oxygen and we’re giving off the carbon dioxide in the water which is then going to be taken in by the plant and the process can continue so that is kind of the cycle of life that we can get energy from so here is an example of a food chain it’s very basic I kind of expect that you already know this sort of stuff so we’re gonna kind of go pretty fast through these things so you can rewind the video if you need to and go back to it but your producers are the base of your food chain then maybe the grasshopper as their primary consumer is eating the producer the secondary consumer eats the primary consumer tertiary consumer eats the secondary consumer and then you have things like apex predators there’s going to be the top of the food chain are going to eat those tertiary consumers I mean you don’t normally go past this because we’re going to talk about how energy flows in just a little while and you’ll see there’s not a lot of energy up here on to be had the other thing is you have decomposers like mushrooms earthworms bacteria down here which are decomposing and taking energy from all of these organisms so really there should be arrows going from the grasshopper the bird and the snake as well and that’s putting the nutrients back into the soil so a couple of terms you should be aware of autotroph is the same thing as a producer Auto means self so you are self making your own food a heterotroph is someone who cannot make their own food so they are relying on the autotrophs to get that food then we have a couple of terms we have herbivore those are things that only eat plants we have carnivore things that only use animals and we have an omnivore things that eat both and again food chains it’s this linear relationship that we see going on now the difference between a food chain and a food web a food web here you see is not that real in your relationship it is more pyramidal so you can draw a pyramid and actually have a food web pyramid um you’ve got multiple producers you have multiple primary consumers multiple secondary and tertiary consumers so as soon as you start adding in more than one individual of any of those trophic levels you get a food web and again you have your producers make sure you know that term and you have your consumers so here is our pyramid if we took that food web and made it into a pyramid this is what it would look like this was normally what we’re gonna see in ecological pyramids your base always has a hundred percent of the energy that’s your producers you cannot have a food web without having a producer and then this 10% role that we see here please make sure you make a note of that this is called the ten percent rule ten percent of energy passes on to each level so say for example we have twenty thousand kilocalories within our producers well ten percent is going to move to our primary consumers ten percent of twenty thousand is 2,000 kilocalories then ten percent of your primary moves to secondary so ten percent of two thousand is two hundred and going all the way up to where we would only have two kilocalories in our quaternary consumers so this is the reason why you’re not going to have another step up there’s just not enough energy to be had to support another level of the food chain why are we losing all that energy well we’ll talk about what loss or dynamics that is but we’re losing it in the form of heat waste and all that kind of stuff are going out so our second law of thermodynamics says no reaction is 100% efficient you lose energy that is the law that tells us that we only get 10% moving through each food web or each trophic level now it’s not always ten percent it could be 20 it could be five but on average it’s going to be 10% so a couple of other things we have pyramid of numbers shows number of organisms at each trophic level in an ecosystem so we have 2,000 plants we have 25 voles and then we have one owl notice it gets smaller as we move up that’s usually how pyramid works however sometimes pyramids of numbers don’t work out too well so exam for example if you’re talking about something like a tree well the tree is very large it has a lot of leaves but we only say it’s one tree so you have one tree supporting a lot of caterpillars a lot of birds and whatever this is a peer cat or Fox or something so this is not a pyramid you want to have your pyramid shaped like a triangle and the bottom down here is kind of weird so we don’t really like pyramid of numbers that much in that you probably will see it sometimes instead of pyramid of numbers we use biomass pyramids so biomass is the amount of dry organic matter present in an organism so literally if you took all of the water out of us there wouldn’t be a whole lot left but all of that stuff that’s left the nitrogen the phosphorus carbon all that stuff that’s our dry organic biomass so it’s the total mass this time not size so now we have the tree down here that has a large mass and then all the other mass of organisms get smaller and we do see that actual pyramidal shape so if we go back to that same pyramid here’s the biomass pyramid instead of the pyramid of numbers and it works out again because now we have that nice pyramidal shape so last thing we’re going to talk about our bio magnification and bioaccumulation in an ecosystem and in a food chain so bioaccumulation is when one single organism accumulates toxins so say I ate something that had toxins in it we’re going to talk about different organisms that do certain types of fish you may have never heard about mercury poisoning before but mercury and fish is going to be consumed by me and I start to accumulate multiple toxins as I’m eating more and more of those fish bioaccumulation is when contaminants start to increase at each step of the food web so this is no longer just one individual this is an entire food web or food chain so down here you’ll notice that the plants don’t have a lot of toxins Oh point zero four or ppm that stands for parts-per-million so please make sure you get that parts-per-million so now the fish that eats the plants is going to have 0.23 because it’s eating a lot of plants it has the pollution in it so this small fish has 0.23 the big fish is eating the smaller fish so now the big fish has 2.07 and then the big bird is eating many of these largest fish that have to sorry this hog sneezing apologize for that and the bird is going to have thirteen point eight parts per million so you’ll notice as we get up in the food chain we have less and less organisms but those organisms have higher amounts of pollution inside of them so I’m gonna play a little game for you if you’re not aware of pac-man you should play pac-man I’ll tell you okay so now let’s go back to what we were talking about and I’ll tell you why we were playing pac-man so imagine that pac-man is a consumer and the consumer or is eating food plants or animals and the pellets are going to represent pollution so here’s our pac-man eating pellets okay so the blue dots are now going to be our pollution threat pac-man ate and then we have a ghost that’s going to eat pac-man and it’s going to end up getting all the pollution so the ghost eats pac-man and now it has all the pollution that pac-man have now the ghost is going to eat another pac-man and it’s also going to get all of that pollution so here the ghost comes and it eats pac-man again so now you’ll notice that the amount of pollution has doubled in that one ghost and it can eat another pac-man and you see how this can continue on okay so the pollution is going to bat Rio magnified through the food chain now this fish is going to come and eat the ghost and it’s going to get all of the pollution inside that fish so when it’s going to eat another fish or another ghost you’ll see you’ll notice that it gets even higher so here’s what that looks like in our food chain we notice again parts per million down here and we’re getting higher and higher as we go through the food chain now if we talk about fish you probably eat fish salmon to know these kinds of things if you consume them the FDA actually sets limits for these kinds of things especially for pregnant women and children because it can get and bioaccumulate inside of you and then it can get into the fetus and cause problems to the baby and actually be toxic and can cause mercury poisoning which we’ll talk about what the effects of that are alright that’s all i have for you today bring your questions tomorrow

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