And so the project is looking at how changes that we expect to see happen
worldwide in the next several decades are affecting ecosystem level dynamics.
Like water budgets, carbon storage and the balance of productivity above and
below the ground.
And community level questions, what kinds of plant, animal, and
microbe species increase or decline in response to these changes.
And the grassland is a great model system for this kind of study because the plants
are small, thousands of individuals can fit into a single one of these plots.
It's diverse, we get a lot of different species in each of these plots,
even though the plots are pretty small, and they have mostly annual life cycles.
So we can see what responses are like over many generations by following the plots
for just several years, whereas if we were trying to work in a forest, for
example, to get several generations will take longer than the amount of time it's
expected to take for the world to get that much warmer.
Experiments like these are cool because they let us get a cause and effect.
They let us look at the interactions among different factors that we're not
going to find together on the natural world through observational studies.
And they also give us a chance to control things like the temperature,
and the nitrogen deposition rate
in ways that give us a clearer sense of what the effects of those changes
are against the backdrop of all the natural variation and noise in the system.
So, they're a great complement to observational studies where we look over
time at how the real world is responding to things like climate change and
atmospheric pollution.
The experiment is set up with 36 of these plots, and each one has a different
combination of warming and elevated carbon dioxide, so it's replicated.
There are nine plots that get each combination of high warming,
low carbon dioxide, high levels of both,
low levels of both, and high carbon dioxide, low warming.
Doing them over and over like that allows us to see how the plots
that are experiencing the same treatment differ from one another, and to see
whether those differences are smaller than the differences between those plots and
the ones that are getting a different combination of warming and carbon dioxide.
It's also a nice way to isolate the different effects of warming and
carbon dioxide.
And then to look at whether when you put them together,
the whole is the sum of the parts or you get unexpected
synergistic interactions between elevated carbon dioxide and warming.
That you wouldn't get just by adding up the separate effects
of those two changes alone.
Let's take a walk up to a different part of the reserve,
to look at a different kind of grassland on the ridgetop of Jasper Ridge itself.