[Music] hi it's Mr Anderson and this is environmental science video 7 it's on ecosystem ecology ecosystems are large areas on our planet that contain both living and non-living material great example could be these giant kelp forest the kelp are producers so they're taking energy from the Sun and converting that into food which is eaten by herbivores like this sea urchin which in turn are eaten by carnivores like this sea otter now the problem with the sea otter is if it dies due to hunting or predation then the sea urchin populations will take off sea urchins feed on kelp by trimming the bottom and sometimes the kelp will simply float away and so if you have too many sea urchins you get what are called urchin Barons where there are no kelp and therefore the whole Eco system kind of folds in on itself and so we like to think of the otter as a keystone species just like on this Arch this Keystone at the top holds everything else in place you can think of each of these Stones now as a different species if we remove move that keystone species then the whole thing folds in on itself in other words some species are actually more important than others before we get to ecosystems we should understand how life is organized from the very small one individual for example sea urchin is in part of what's called a population or all the Sea Urchins in an area we then take all the populations together that's a community we then add the non-living material that's an ecosystem and then we even have larger areas which are called the biomes what's larger than the biomes that's going to be the biosphere here it's going to be our planet and so before we get to ecosystems we'll start by studying the major biomes both terrestrial or landbased and Aquatic those in the land we'll then move on to the interactions at the ecosystem level so that's going to be all of the producers and consumers interacting a good way to study that is going to be with their food webs we're also going to add abiotic or non-living material we'll then jump to individuals and the the role of a niche or a niche that's going to be the job that an individual has we'll then move to the importance of keystone species diversity and then finally Edge effects in keeping that ecosystem healthy and so let's start with terrestrial biomes a desert could be an example one a forest a boreal forest could be an example now there's really only two properties that determine what biome we're going to have that's going to be the temperature average temperature and the average precipitation so you could be given a map and just told what is the average temperature and precipitation you you could make a pretty good guess as as to what the biome is going to look like and so we graph those on a graph where we have precipitation on the Y so that's going to be the amount of annual precipitation from 0 to 400 CM a year and then we look at temperature from the very cold on the left -10° Celsius as an average up to 30 plus degrees uh Celsius you could kind of guess as to what biome are we going to find where it's really really hot and where it's really really moist you could even point to it on our biome map that's going to be the tropical rainforest and so what you can do on this map is just read precipitation temperature that tells you the biome if we were to go in Africa right here and then move to an area where it's still hot but we have less precipitation that's going to be a tropical forest or Savannah you're probably familiar with that if we keep moving up so we have even less precipitation then we're going to get into a subtropical desert and you can see those uh at this latitude and at this latitude right here if we keep going across from Africa though let's go up here we're then going to have temperate grasslands sometimes we have temperate deserts you can see that we have a lot of those in the in the Midwest rest of the United States if we keep going then we're going to get to temperate seasonal forests if we keep going then we go to the Boreal or Northern Forest and then we eventually get to the tundra so these are the major biomes we could fill in a couple of other ones so right here in the Mediterranean we're going to have Woodland shrublands we would have that over in California as well and then if we go up here we'll have these temperate rainforests where it's cooler but they receive tons and tons of precipitation throughout the year and so you can see those are the major biomes if we start looking at aquatic biomes it's not temperature and precipitation cuz water exists and so it's going to be salinity the amount of salt the depth within that water and then the flow of the water and so the first way to divide the Aquatic biomes is to those that are freshwater and those that are going to be saltwater if we look at those that are freshwat you're probably familiar with almost all of these wetlands are areas where we're going to have water for a large portion of the year but we still have vegetation in that area we could move from there to areas that kind of are in the boundary between fresh and salt water so a salt marsh is going to be an area where we have water flowing in so we can have a mix of fresh water and salt water estuaries are like this or we could have mangroves those are areas Mangrove is kind of based on a a tree that can grow in salt water and those are important as a border between marine and terrestrial systems and then as we move out to the ocean itself we have interner tidal zones so that's going to be when the tide comes in and out that thin area along the coast coral reefs you're probably familiar with in open Oceans open oceans are really not a super productive ecosystem out in the middle of the uh ocean only near the top where we get a certain amount of light so now we're going to go from biome to ecosystem so this is going to be a smaller area but it's still really big one of the most famous ones in the world is the greater Yellowstone ecosystem it's really just north of me I live right here and so it's bordered by Montana Idaho Wyoming and Wyoming but it's not just Yellowstone National Park that makes out the ecosystem it's going to be this whole area around it which is going to contain the national park but also national forest and private land as well it's a really large area also includes all the abiotic or non-living material so for example the temperature the pH of this water the flow of that water are all um all considered when we're thinking about the ecosystem now let's go to the parts of the ecosystem so everything is built on these producers and so those things that do photosynthesis if we look at a terrestrial versus an aquatic we're going to find the same kind of a transition we got the plants at the bottom the herbivores then we have carnivore and carnivores on top so we have these different levels of consumers as we move up they're organized in what's called a food chain and the arrow is going to show where the energy is going or where the food is going so food goes from the the plant to the insect itself students sometimes confuse which way the arrows go and here's an easy way to remember that so just think of the arrow as the mouth of what's eating it so if this is the mouth of a fish we know that the arrow always goes from the food to what's eating it or the organism to what eats that organism if we organize all the food chains in an area then we have a food web and so it's going to have producers on the bottom and then it's going to have the consumers above that different levels of consumers um if you look we've got Aquatic and terrestrial all mixing in some terms that you may be familiar with are herbivore herbivore is going to be something that just eats plants we've got carnivore something that just eats other living things but we also have an omnivore that's going to be something that eats plants and other living things um keystone species remember is going to be a species that keeps everything kind of in check in that ecosystem and I'm really leaving off a bunch which is going to be all the decomposers so as material dies we have to recycle that so that's going to be decomposers an example are DET travores that can eat large bulk amounts of dead material what's the niche now we're at the level of an individual so a niche you can think of as like the job of an individual so if we take this squirrel and say how does a squirrel perform over different temperatures well we're going to get a distribution like that the there going to be areas where it can survive outside that would be areas where it dies if it's too cold or if it's too hot as we move closer to the middle we get areas where it can survive and grow and finally where it can survive grow and reproduce and so the environment has a lot to do with the niche but also what we're using as a food source so this dung beetle for example exploits a niche by taking dung rolling it up and using that as an eventual food source what else determines it then not only the environment but the resources the food that you need or the space you need to live in and so we can represent that on this on this graph as here's the two resources I need and that's going to be my fundamental Niche that's where this squirrel could live now what you'll find is that it actually doesn't fit that way you have what's called a realized Niche where it could live in all that areas but it only lives in this small area and the reason why you're probably guessing is that there are other niches outside that there's competition going on species diversity is actually good it's good to have all these different species so let me use this model to show you how that works imagine we have species that are just cold tolerant they love the cold warm tolerant they love the Heat or a nice diverse mix of the two and so let's say we apply some cold weather what happens all those that aren't cold tolerant die you can see the warm tolerant are going to be most affected you're going to see the the diverse species in the middle and the cold ones are doing fine but let's say we change it up now and it's really hot then we're going to have this impact and so right here by having a diverse population this doesn't have to deal just with temperature but it can be resources you're feeding on the more species we have the healthier that ecosystem is going to be that even applies at the individual level so a a raccoon is what's called a niche generalist it can eat lots of different food resources can live lots of different areas whereas a koala can only eat eucalyptus leaves which of these you think is more susceptible to change in that environment definitely going to be the koala since it's only in on one thing if that resource is impacted it's going to be impacted as well the edge effect also affects the health of an ecosystem Edge effect is going to be a boundary between two ecosystems it actually can be a healthy area so if it develops over a long period of time what you'll get is this transition from here into the forest and so that's an area where we can actually support more species the problem is that humans lots of times will just create an edge so we make a trail or we make a road and now what happens is there's not this natural boundary and that can damage the health of the ecosystem the size of the edge is always going to be the same and so watch what happens when I take this shape think of this as a protected area so the edge will always REM remain the same but watch what happens when I shrink the protected area The Edge becomes a larger proportion let me even shrink it up even more and so that edge becomes the largest thing and so if we're trying to protect an ecosystem protect an area it's important that we have the largest area with the healthiest Edge that we possibly can and so did you learn the following can you pause the video now and fill in the blanks well I hope so but I could work through it it goes from Individual to population to community ecosystem biome major examples are terrestrial and Aquatic could you list some of those we've got interactions between producers and consumers keystone species diversity and then the edge effect can affect the health of the ecosystem and then remember the niche is the role of an individual it's kind of like its job I hope you learned that and I hope that was helpful [Music]