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Main content
Current time:0:00Total duration:4:40
AP.ENVSCI:
ERT‑2 (EU)
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NGSS.HS:
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Video transcript

you look at a community that is in a given habitat a natural question is to say well has that community always been that way has it always been there was there time where maybe there was no life there and the answer is well yes the communities do change over time and there is some initial period where there might not be any life at in that habitat and then life slowly colonizes it and the makeup of that life will change over time the makeup of that community and this general idea is called ecological succession ecological succession and folks will often talk about the different types of ecological succession splitting it up into primary ecological succession and so primary is when you start with no life because you really have a new habitat and then slowly life colonizes it and the best example of that or one of the best examples of that is when you landforms due to lava flows these are pictures from Hawaii where new land is forming as this lava hardens and at first there is well when it's when it's molten lava there's no life there then it hardens and slowly the basic life or life in general will start to colonize that that lava rock and some of it you won't be able to see with your naked eye it would be microbes and some of it you could see it could be simple ferns and and plants like that and these are often called the pioneer species but what they often do is make that environment more suitable for other types of life so they might slowly break down that rock as they die along with the broken-down rock that also gets you roaded from the water and the air and the rain it starts to make soil and conditions more suitable for other types of species and these pioneer species they don't even have to just be plants and microbes I was just reading an article about how in Hawaii it humans want to get that land because it's it's it's beachfront property or the beach might have not formally formed in the traditional sense but you have ocean view property so humans might be some of the first pioneer species who might want to be out that land and that new land doesn't just form from lava flows there are other examples of new habitats forming so right here we have pictures of a new habitat forming because of the retreat of glaciers when the glaciers were covering up these rocks you didn't have life on them but as the glaciers as the glacier retreats right over here you see things like these mosses and other types of pioneer species starting to colonize and over time they're going to make it more and more suitable for other types of species so that's primary succession another situation is when you have secondary succession and there's many different ways you could have secondary succession one of the often is one of the most one of the most cited examples is when you have some type of a disaster and so this right over here this is a picture of a fire so we're here we're talking about secondary secondary succession where you had a community but then you have a fire and so that fire might wipe out a lot of the community and then it creates space for other things to form so after you have a fire the forest might look something like this and then notice you have more you have species that start to colonize where a lot of other species might have died or died during the fire and sometimes after this this disaster of some kind you might you you might get back to the same type of community that you had before the disaster but sometimes it could be a completely different one that the communities don't don't don't come about in the exactly the same way so the general idea is communities change over time we have ecological succession there are times where there's no community and then they come in that's primary succession and then you have times where you have disasters of some kind that could change the environment in some ways that it could change the makeup of that community and things don't have to be as dramatic as new land formation because of lava or because of forest fires or even glaciers retreating it could be because of a disease or it could just be because a new species gets introduced somehow that changes the makeup changes the competition the predatory the various the symbiotic dynamics within that community
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