Willow Head
Willows pioneer new territories and create an [environment] that enables other plants to gain a foothold. Their windblown seeds usually root in sunny land opened by fire and agriculture. Since these trees require a great quantity of water, the solution holes in the glades are favorable sites. Seedlings grow, leaves fall, and stems and twigs die and drop—contributing to the formation of [peat]. When this builds up close to or above the surface of the water, it provides a [habitat] for other trees such as sweet bay and cocoplum; with enough of these the willow head changes character and becomes a bayhead.
Years ago, when alligators were plentiful, they weeded the willow-bordered solution holes, keeping them open. Consequently, the willow heads were typically donut-shaped. Today, however, alligators are scarce and many of the willow heads have no ’gators. The solution holes fill with muck and [peat]; relatively tall willows rise out of the deep, peat-filled centers, with increasingly smaller ones toward the less fertile edges, and the willow heads take on the characteristic dome-shaped profile but not nearly the height of the cypress domes. They have a clumpy, brushy appearance, seeming to grow right out of the [marsh] without trunks.
POMACEA SNAIL—The sole food of the [everglade] kite
[EVERGLADE] KITE
Willow heads with alligator holes typically have a doughnut shape—the gator hole representing the hole in the doughnut.
SPATTERDOCK COASTAL PLAIN WILLOW CATTAIL DRY SEASON WATER LEVEL
Willow heads that do have alligator holes have a seasonal concentration of aquatic animals and the birds and mammals that prey upon them. They rarely support orchids or [bromeliads], for the bark of the southern willow is too smooth to provide anchorage for the seedlings of these plants.
During drought periods willow heads, like bayheads, are vulnerable to the fires that sometimes burn over the glades.
Web of Life in the [Marsh]
Around the stems and other underwater parts of the glades plants are cylindrical masses of yellowish-green periphyton. So incredibly abundant are these masses of living material that in late summer the water appears as though clogged with mossy-looking sausages and floating pancakes. Largely [algae], but containing perhaps 100 different organisms, the periphyton supports a complex web of glades life. It is the beginning of many food chains in the fresh-water [marsh]. The larvae of mosquitoes and other invertebrates, larval frogs (tadpoles) and salamanders, and other small, free-swimming creatures feed upon the tiny plants and minute animals living in the masses of periphyton. These periphyton feeders are in turn fed upon by small fish, frogs, and other vertebrates, which are food for big fish, birds, mammals, and reptiles; most of these larger creatures are preyed upon by the alligator.
The periphyton is perhaps most important for its role in maintaining the physical [environment] of the [marsh]. The water flowing over the [limestone] of the glades is hard with calcium. The [algae] remove this calcium and convert it to [marl] (see glossary), which precipitates to the bottom. Sawgrass is rooted in this marl; accumulated dead sawgrass forms [peat]; other marsh plants, including willows and the trees of the bayheads, spring up from the peat. Acid from the peat and from decaying plant matter of the tree islands dissolves some of the marl and underlying bedrock—and the cycle is complete.
Every plant, every animal, every physical element is involved in this web of life—as soil builder, [predator], plant-eater, scavenger, agent of decay, or converter of energy and raw materials into food. Damage to or removal of any of these components—pollution of the water, lowering of the water table, elimination of a predator, or any interference in the energy cycle—could destroy the glades as we know them.
BEGINNING OF [FOOD CHAIN]
[ALGAE] AND ONE-CELLED ANIMALS INVERTEBRATE LARVAE PERIPHYTON MASS SAWGRASS SAWGRASS DIES AND MAKES [PEAT]
Every other plant-and-animal [community] in the park—[hammock], [mangrove] [swamp], pineland, etc.—is an association of large and small organisms sharing a physical [environment]. It is impossible to understand either the park as a whole or the life of a single creature without being aware of these interrelationships.