Mythical Big Cypress

Big Cypress Watershed
Or is the term "mosaic" a better descriptor?

Animated cross section of the rise and fall of the water table in Big Cypress National Preserve
Swamp water cycle in motion

In the modern era, we’ve come to know the Big Cypress as a watershed. But what if I were to tell you, use of that term for the Big Cypress is as new as the preserve? Yes, that’s right, the day Big Cypress National Preserve was established in 1974, it was dubbed a watershed – it’s own watershed, a watershed separate from the Everglades and the Lake – and has been thought of in that pristine, almost utopian way, ever since. But the truth is the Big Cypress is only a watershed because its original “other sources” of water were drained away, or diverted.

Listen to Audio Introduction

What were those sources? Lake Okeechobee and the Everglades definitely flowed into the swamp. If you don’t believe me, just read the Buckingham Report from 1848. And prior to the destruction of the Ft. Thompson Falls and drainage of the Upper Caloosahatchee Basin (Lake Flirt, Lake Bonnet and Lake Hicpochee), the swamp was fed water through groundwater seeps from the Immokalee Rise.

Before, Current and Future Restored Maps of the Big Cypress Swamp
The rainfed swamp we know today was once fed by upstream water sources

So yes, in a way the Big Cypress we know today is a rainfall-sustained ruins of a pre-drainage cathedral of of headwater flows, now largely collapsed (by drainage). That doesn’t make the swamp any less special. In fact it makes it more interesting than we knew. And it also points to our need to steward water. The sky provides the Big Cypress with a bounty of water. But it needs help, our help, to make sure its clean, connected to its remnant headwaters where possible, and help it spread out.

And the swamp needs fire, too. Every square inch of flora and fauna in the swamp depends on a regular return interval and dosage of flood and fire. Those are the two forces that give the swamp its distinctive mosaic of habitats. The cypress may look “old as the hills” but they are actually holes — although it is incorrect to call it a homogenous swamp.

More correctly stated, it’s a malleable swampy mosaic that’s semi-fixed in time and space. Or as we like to say around here:

So goes flood and fire, so goes the swamp.

flood and fire

Rise and fall (of flood and fire)
And why fire and water are the swamp's best friends

A very wise swamp rat once said:

“So goes flood and fire, so goes the swamp.”

Can you see the decadal shift in the swamp’s seasonal distribution of wildfire? Green are prescribed fires, red are arson and yellow lightning strikes.

And probably nothing explains how fire has changed …

In recent decades than the graph shown above.

Or check out the full presentation in the video below.

A brief history of flood and fire in the swamp

Everyone is always ready to blame the water …

For every Everglades woe.

But let’s not forget that fire is the flip side of the same coin.

A healthy swamp depends on getting both right.

History of flood and fire
As presented at GEER 2021

Here’s the thirteen minute presentation

I gave at the recent Greater Everglades Ecosystem Restoration (GEER) conference on Tuesday April 21, 2021.

GEER 2021 Video

Normally, a talk like this, you give it once and nobody hears it again.

And that means only a couple dozen people at most. Thus it feels good to be able to post the video here. Partly that’s possible because it was a Zoom conference and I had to tape it in advance.

Stunnning conclusion: The swamp is flood and fire adapted

But it is also in tune with my personal philosophy as a hydrologist, which goes something like this: I may not know everything, but I know enough to share.

I’m still working on my catch phrase by the way. Enjoy!

P.S. Here’s a supplemental video expands on the discussion above by touching on the topic how initial conditions powerful influence our personal understanding (and biases) of about an ecosystem. As the years and decades pass, the ecosystems change, yet so often we find our thinking moored and mired in the past in ways that both illuminate and cloud our thinking.

Initial impressions sometimes need revisiting

Read more

Degrees of drought
How the swamp is simultaneously wet and dry

Drought in the swamp?

It almost sounds like a contradiction in terms.

audio introduction

But come every winter the water table (almost) reliably drops to the point, at some point in the spring, much of the swamp is bone dry.

Actually, the term “swamp” is a bit of a misnomer.

History of drought in Big Cypress National Preserve

A better way to describe the habitats of the Big Cypress is as a mosaic.

Read more

flood and fire

Swamp riddle
Why did the hydrologist cross the road?

I thought I was crossing the road …

To look at the wildfire.

View of Tamiami Trail in Ochopee looking north

Then I noticed the cormorants …

On the dead cypress trunks killed by saltwater intrusion last spring.

Back in the past they would have been anhingas.

Front seat view to the wildfire

Every square inch of flora and fauna is adapted to some dosage and return interval of flood and fire.

So goes flood and fire, so goes the swamp.

Bountiful rainfall

How much rain does it take …

To fill up the swamp?

Historic rain chart for October and November

Answer: This October and November combined to deliver 12.5 inches of rain. That’s two and a half times the normal rainfall for the two month span.

And was enough to do the job.

Eta-flooded marl prairie (and dome)

More about November rains:

They make every drop count. Unlike summer rains that evaporate into the warm air and abetted by transpiring plants, Eta coincided with the onset of the swamp’s low evapotranspiration period, a span that typically lasts from November through February. That leaves only gravity and a very flat swamp to drain the water off, a process that is always slow but even more so this year due to the the coastal area south of the Tamiami Trail being already flooded prior to Eta passing through.