self regulation (Flora population)

[YT2095]

2 years ago I started with a single barley seed, that developed 6 ears and each had roughly 40 seeds per ear (a 1:240) ratio.

I planted them all again early this year and now have just over 2kgs of seeds, now at the 1:240 ratio that`s roughly 57,600 seeds in 2 years from a single one!

I plan on do the same next year and calculate over 13 million seeds in 3 years!

that adds up to about 553kgs and a whole lot of land being taken over.

I find that quite an impressive feat by good old mother nature, but what`s really "scary" is the Pumpkin!

a single plant will grow at least 10 pumpkins, and each pumpkin will have nearly 2000 seeds in it, so from 1 seed in one season you could have 20,000 seeds!

now imagine this pumpkin doesn`t get chopped up and sold in the shop, these seeds will all try and germinate again comes the right time next year, making billions of them and so on....

 

how come this doesn`t happen though?

why are we not over run with pumpkins and barley and wheat etc...?

what govourns this population control?

[CPL.Luke]

I think most of it is governed by just the fact that very few of the seeds will ever get successfully planted. in the casee of the pumpkin animals will break it open and eat the pumpkin killing off most of the seeds.

 

Even assuming a pumpkin never gets eaten and all of the seeds come out of it alright, there not going to be distributed over a huge area, and because one acre of land can only support so many plants, most of the seedlings (is that the proper term for a newly growing plant) will die off from lack of resources to live.

[5614]

Also the area where they are will become overpopulated with the plants and they will start competing for resources, so either they all lack nutrients (because there's not enough for all of them) or some of them die off.

[YT2095]

well when you consider that the leaders from a pumpkin go 25 foot (any direction) they`de still spread at an alarming rate surely?

[CPL.Luke]

but then animals come and eat them

 

or other more invasive plants force there way in and start using up resources. notice how we are overrun with grass

[YT2095]

I`de agree to a point, yes I have seen rats eat the majority of a rotting pumpkin before (oddly never before this decay), there are still 100`s of viable seeds left though.

 

also take a look at common waste ground, it`s never all taken over by any ONE particular species of plant, and for some reason they seem to have some type of "order"

 

it`s that "Order" that confounds me.

[Mokele]

Ok, ecology's not my best subject, so bear with me.

 

Say you've got a plot of land, as you do, and your plants just keep making more seeds, which make more plants. Since your land is not infinite, nor does it contain infinite resources, some plants will eventually fail to thrive or just die. Maybe space became the limiting factor because the roots didn't have enough room, or maybe it was this or that soil nutrient. Maybe even just how much solar energy enters the plot isn't enough to sustain all the plants. So the surplus individuals die, and then it becomes a normal evolutionary scenario, with only the best surviving the competition for sun, space and/or nutrients.

 

As for this "order" you mention, IIRC, the correct term is "succession communities". Lets say you just paved over you entire yard. Eventually, lichen would grown on the rock, and gradually break it down into a poor soil. Mosses are better growersthan lichens, but as such need more nutrients, so only after the lichens have established some soil can the mosses move in. They, in turn, by biomass accumulation, generate better soil, and common weeds move it. And so on and so forth until you have a "climax community", with no further levels of sucess (typically old-growth forest is a "climax community"). It tends to be the most rich in both biomass and diversity.

 

At least, that's what I recall from the times in ecology when I wasn't asleep.

 

Mokele