© 2008, Weston

ECOLOGICAL SUCCESSION…some of the most common-sense stuff you’ll ever “learn” in scienceclass.

About time, right?

#1 So what is “ecological succession?”

Ecological Succession – a predictable series of changes that anecosystem goes through over time

For example, ecological succession can describe how a parkinglot can turn into a forest.

#2 So, it’s just a step-by-step process?

Yeah, pretty much. Of course, the steps don’t occur identicallyin all situations, but the key is that it’s a fairly orderly &predictable process.

Two things to remember about succession:•It’s a slow, gradual process that is often hard to spot as it happens•It’s happening right now, and likely in places VERY close to home

Nah, it’s not a big deal, really. Nothingto worry about.

#3 Different kinds of succession

Succession comes in two main varieties, depending on the startingconditions of the ecosystem.

It’s like with cooking. I can say, “hey…make me some hot dogsfor dinner.”

The quick & easy method: Get hot dogs out of package. Microwave. Stick dogs in buns. Serve.

The slowwwwwww method: Find baby pig. Start to raise pig.Plant tomato, mustard & wheat seeds…you get the idea.

#4 The “slooooow” successionPrimary Succession – starting a new ecosystem from an emptyhabitat.

Perhaps after a volcaniceruption wipes out an area

Or maybewhen ahugeglacier hasscraped away allsoil and living things.

#5 Primary SuccessionSo, primary succession means we’re basically starting fromscratch. Let’s use that volcanic island as an example.

Wow. What a little paradise. But that volcanic islandhas been storing potential energy for years…

#6 Primary Succession, contd.

Whoa! Potential Energy gone Kinetic, and it’s hot, too!

#7 Primary Succession, contd.Not only would the lava kill every single living thing inthis area, it would also cover & eliminate any quality soilthere, too.

The lava would eventually cool to hardrock.

#8 Primary Succession, contd.Uh…now what?

Well, as tough & crusty as that rock might be, to some organisms,this is a great opportunity for thriving & prospering.

In this case, some crusty little producers likealgae & lichen fly in on the breeze…

And these little plants are solely responsible for bringing a healthy ecosystem back to this barren island. Such heroes!

#9 Primary Succession, contd.These plants are what we call a pioneer species – they are thefirst to arrive at a new habitat and begin constructing an ecosystem

Think of how difficult it must be to break rock apart,both chemically and physically, into what can be called“dirt.” It must take for freakin’ ever. And it does.

…and that’s what the pioneer species does…they might take hundreds of years to build up just a couple inches of dirt, but thisis a necessary step in re-establishing a healthy variety of life here.

#10 Primary Succession, contd.Good work, little plants. You are so simple that you can live inplaces where other organisms just can’t survive. But now that youhave done the dirty work, other organisms will take advantage ofyou. Sorry, dudes.

soil

Plant seeds

#11 Primary Succession, contd.

Larger producers, like grasses, sprout up in theshallow soil. Soon, they spread like, well, grass.

This is important, as these larger plant roots will help drive apartrocks, somewhat speeding up the soil-creation process

#12 Primary Succession, contd.And as you know from the food chain, in places where producersthrive, consumers will soon follow. Herbivorous insects are likelythe first to show up.

And where herbivores gather, carnivores will likely appear.

#13 Primary Succession, contd.And higher level consumers will be attracted by these insects &bugs.

A few larger trees start to grow, species sort themselves out in the food chain, and given many years, BLAMMO! A new, healthy ecosystem!

#14 Primary Succession, contd.…and the ecosystem balances itself out, while plants & animalsstruggle to survive & adapt to the young habitat.

…and then the volcano erupts again, destroying everything.Yep. Nature can be cruel.

#15 Primary Succession, reviewed

•Begins with bare, empty environment•Pioneer Species arrives, building up soil•Larger producers grow in new soil•Consumers arrive to complete food chain•Ecosystem continues to adjust & balance itself over time asorganisms struggle to survive & adapt to changing conditions•A LENGTHY process, mainly due to step 2

Easy!

#16 So, what’s the Oscar Meyer version???

Secondary Succession – establishing an ecosystem in an areawith existing soil/organisms.

Maybe after a forest fire

Or if a farm is abandoned

#17 Secondary Succession

So, secondary succession means that soil and living things likelyalready exist, but something has happened to throw things way outof natural balance.

Let’s use the abandoned farm example.

Joe decides that he hates farming. Hegoes to the city to teach science.

#18 Secondary Succession, contd.

Well, what’s gonna happen to Joe’s farm? One of the first thingsis that, obviously, nobody cuts the grass around the barn anymore.

This grass is very likely NOT native to this part of the world. Joe chose it because it looks nice, but it has a hard time livingwithout his help.

#19 Secondary Succession, contd.

This is where weeds come in. What are weeds, anyway? Really,they’re highly successful, adapted plants that we happen to thinkare ugly. That’s it. Now that Joe isn’t around to yank them out, the native weeds will start to fight the foreign grass.

#20 Secondary Succession, contd.And there’s a good chance that Joe’s weekly mowing was cuttingdown an oak tree that was trying to grow here. Now’s its chance.

And the sheep and cows and chickens? Hopefully Joe sold themor gave them away, but if he didn’t?

The biome’s natural carnivores, which Joe had probably had toscare off with his shotgun, will make quick work of the livestock.

#21 Secondary Succession, contd.

And as the months, weeks, years go on?

The plants will revert more and more to the native dominant species.

More native species will replace the unnatural selections of thehumans before them.

And you can see the progression that takes place as the farmis transformed into a natural habitat.

#22 Secondary Succession, reviewed

•Begins with an area ready to support life…soil already exists•Highly adapted organisms quickly jump in to take advantage ofthe new opportunity•Ecosystem continues to adjust & balance itself over time asorganisms struggle to survive & adapt to changing conditions•A faster process, because we don’t have to wait centuries forsoil to be created.

Easy as…

#23 Does Succession End? Can We Eat Our Hot Dogs Yet?

Well, in some cases, succession will slow or come to a stop whenthe ecosystem reaches a point called equilibrium – it is balanced,healthy, and diverse. Few major changes happen from that point.We call the organisms here a Climax Community.

However, in most cases, succession is SO slow a process thatsomething drastic will come along and really throw things for aloop before it ever reaches its climax, or end—equilibrium is notusually achieved.

Climate changes that affect succession are very common, and thinkabout what a powerful natural disaster can do to an ecosystem trying to reach equilibrium.

#24 So, it just depends if you’llever actually get to eat your…