hey everybody its mr. smith's welcome to video notes for topic one point two which is terrestrial or land based biomes our objective for the day is to be able to describe the global distribution and the environmental conditions of land-based or terrestrial biomes we'll talk about how the plants and animals that live in a biome are adapted to that unique climate will go over major must-know biomes for apes we'll talk about how the worldwide distribution of biomes is subject to change if our climate changes and finally the environmental science skill that we'll practice at the end of today's video we'll be explaining an environmental concept or process so biomes are areas that share a combination of average yearly temperature and precipitation also known as climate this is really important to point out climate is just a combination of average temperature and precipitation trends over a year so we can look at some examples of well known biomes we have the rain forest of course this is going to be a biome that over the course of the year is going to have really really high rainfall as well as really really warm temperatures whereas the desert is going to be a biome that's characterized by very very low precipitation now it may also have high temperatures but that low precipitation is the big distinguisher between the tropical rainforest and the desert really important to point out that the community of organisms that live in biomes are uniquely adapted to the climate of those biomes so this is our sort of thinking like a mountain opportunity because instead of thinking of the biome and trying to memorize what organisms can survive there just remember that any organism in a biome must be uniquely adapted to survive those climate conditions so we've got some examples here we have camels and cacti camels have hump which store energy in the form of fat four times when they are unable to find energy for a long period of time I have thick waxy cuticles or coats that basically prevent water loss through evaporation so those are both adaptations that allow those organisms to survive the harsh dry conditions of the desert we have shrubs and wild flowers they're gonna have long deep roots that store a lot of energy so that when there's wildfires that devastate the landscape of the that they live in they're gonna be able to quickly regrow because they've stored so much energy deep in the ground in their roots so again the organisms of a biome are uniquely adapted to survive the conditions meaning the climate of that biome now we'll talk about characteristics of biomes the two most important characteristics of a biome are its temperature and precipitation in fact they are the defining characteristics so if we look at a graph here we'll see that we have different ranges of both temperature and precipitation foot so for instance if we look at the tropical seasonal forests also notice the savanna will notice that they range in annual precipitation from maybe 60 or 75 centimetres of annual precipitation all the way up to maybe 280 and then if we look at the temperature will notice that those tropical seasonal forests are gonna range from oh maybe 18 degrees or so all the way up to about 29 degrees Celsius so just keep in mind that all of these biomes are defined by the range of precipitation and temperature found in them what we'll notice is that these temperature and precipitation ranges will also predict wäôre on earth we can find the biomes so we can look at the biomes mapped across Earth's surface and we'll see that there's very predictable patterns if we look at biomes such as the tundra and the boreal forest if you remember from our graph they're very low in precipitation and they're also colder biomes so we're gonna see them farther away from the equator concentrated around 60 degrees latitude now if we look at the temperate biomes these are gonna be things like temperate grasslands temperate seasonal forests we're gonna see them concentrated on the middle latitudes between 30 and 60 this is because these are latitudes that receive a moderate amount of rainfall and them have a moderate temperature year-round so they're gonna be reasonably warm but they're gonna get somewhat cool in the winter and then finally we have the tropical biomes so this would be the tropical rainforest and the tropical seasonal force or the savanna and we'll notice that they're concentrated around the equator and that's going to be characterized by really warm temperatures because it gets the most direct sunlight and really high precipitation so again instead of trying to memorize all of these different biomes we need to think about how these patterns of temperature and precipitation are influenced by the distance that we are from the equator and that's going to tell us where we're gonna find different biomes will see our colder drier biomes up near 60 degrees and north so the further away we get from the equator will see our temperate biomes in those middle latitudes around 30 to 60 degrees and then we'll see our tropical are really warm and are really brainy biomes near the equator another very important characteristic of biomes is their nutrient availability now this is because plants need soil nutrients in order to grow so the availability of the nutrients in the soil is ultimately going to determine which plants and how many species of plants can survive in different biomes so we have a great example here we can think about the tundra now you could have memorized that the tundra has a lot of snow and ice and so it doesn't have as many plant species but we want to try to actually understand the reasoning behind that so because the soil in the Tundra is permanently frozen year-round that limits the decomposition of organic matter which recycles nutrients so because those soils are so frozen for so much of the year we don't recycle our nutrients and so there are low nutrient levels in the soil that's gonna also lead to low water availability due to it being frozen and then finally that's gonna result in very few plants able to survive these conditions so we can see here that the active layer the layer of the soil that thoughts out each year and is available for plant growth is very small compared to the permafrost again that results in very few species of plants being able to survive here and therefore fewer animal species as well now we can look at a few more examples the tropical rainforest even though it has a ton of plant growth and you might think it has a really nutrient-rich soil is actually going to be quite nutrient poor and it's because there are so many plants that are competing for the nutrients that they get quickly absorbed in the soil as soon as they're made available then we have the boreal forest boreal forest remember our cold they're gonna be dominated by coniferous trees like pine trees Aspen spruce and they're going to also have nutrient poor soils but for a different reason it's because the temperature is so low for much of year that the decomposers like earthworms and fungi are not going to be able to break down dead organic matter fast enough to cycle those nutrients quickly then finally we have the temperate forests those are the force that you're used to seeing in West Michigan and it costs much of the u.s. they have very high nutrient levels in the soil and that's because they have broad leaves like Oaks and maples that drop their leaves each fall that leads to a lot of organic matter on the forest floor and they're moderate temperatures are gonna allow for a faster rate of decomposition which makes those nutrients available in the soil so this is a great example of how another biome characteristic nutrient availability ultimately determines which plants and which animals can survive in that biome and finally we talked about how biomes can shift in their locations that is because climate is not stable on earth climate is subject to human activities that are changing it rapidly right now and so as the climate continues to warm that will shift biomes such as the boreal forest further north as those soils that used to be frozen for much of the year are thawing out and able to have the large tree species of a boreal forest now grow in those conditions they're also going to lose some of their southern range as it becomes too warm for the trees that dominate that boreal forest biomes such as Aspen in screws so we have here the current range from 1971 to 2000 of the Aspen which again is a very characteristic tree species found in the boreal forest versus the predicted change in that biome from 2007 t1 to 2100 we noticed that the predicted range is far further north again that's due to these soils that were previously frozen thawing out an enabling tree growth further north and a lot of those southern regions that we see in the northern US and in southern Canada becoming too warm for these tree species we can see an actual picture of this progress happening these are photos of the same exact Arctic plot of land in 1962 and then again in 2004 and we can see that the forest is slowly creeping northward as global warming makes those previously too cold soils warmer for the boreal forest tree species to survive in our practice up our queue for topic 1.2 today will involve the skill of concept explanation so I want you to identify one characteristic of a biome and then explain how that characteristic determines the community of organisms that are found in that biome alright everybody thanks for tuning in today don't forget to like this video if it was helpful subscribe for future apes video updates and check out other notes over here to the side and as always think like a mountain right like a scholar