I'm Erika Zavaleta and this is Ecosystems of California.
We're near Gilroy today on a agriculture field trip.
Now California is by far the largest agriculturally producing state in the US,
both in terms of its sheer production and
in terms of the diversity of what it produces.
Much of that agricultural production depends on a complex system
of water capture, transport, and irrigation.
So what does agriculture look like in California, ecologically speaking?
Three big ecological dimensions of agriculture in our state are one,
its effects on the state's cycling inflows of water.
Two, its effects on the state's land cover.
And three, its effects on the stocks and flows of fertilizer and
other farm inputs across ecosystem boundaries.
Agriculture uses about 80% of California's water,
that's down from closer to 90% in 1960s.
And in parts of the state where significant irrigation water flows back
into rivers, lakes, and groundwater, agriculture also affects the salinity,
nitrate levels and other features of water quality and chemistry.
With respect to land cover,
agriculture covers about 10% of California's land area.
And certain ecosystem types, like wetlands and grasslands, have had a especially
large proportions of their former area converted to food production.
For example, only about 5% of the wetlands that existed in California
in 1900 remain today, largely because they were drained for agriculture.
With respect to farm inputs, the worst period of pesticide pollution has passed.
And in the 1970s with the banning of DDT and
similar organic compounds, we lost a lot of the really serious impacts on
wildlife that were occurring in the state half a century ago.
But that kind of thing continues to remain an issue.
And one of the biggest and pervasive issues in the state continues to be
the effects of agricultural inputs of nitrogen and
phosphorous on both bodies of water and the atmosphere.
So, what does a managed agricultural system look like in California?
They're incredibly diverse.
And that's even if you look at one crop.
First, California's significant crops range widely,
from things like almonds to lettuce, grapes to alfalfa, and artichokes.
And they inherently look different because of the life histories and
ecological characteristics of the crops themselves.
Whether they're trees, vines, grasses or non-woody flowering plants, and
what part is harvested, for example.
But you can also take a single crop.
Strawberries are grown on large conventional farms like this.
And they're also grown on small organic farms like this.
With more natural vegetation, fewer inputs, less exposed soil, other
crops nearby, and different patterns of interaction with surrounding ecosystems.
It's that idea that we want to dig into some more on our agricultural
field trip today.
The idea of interactions between farms and the larger ecological landscape.
