It's early fall, and during my recent walk in Hogback Ridge Preserve, it was clear the trees and other plants are way past their prime.

It's early fall, and during my recent walk in Hogback Ridge Preserve, it was clear the trees and other plants are way past their prime.

Sure, many are still green (except where the hot, dry weather has taken its toll), but a closer look shows there are crunchy edges to the leaves now, and some are even starting to take on a reddish or yellow cast

It only takes stepping on a few acorns or seeing a hickory nut fall to the earth to realize that some of each plant's energy has been transferred to its seeds and the cycle of life has entered a new phase.

A lot depends on those seeds, whether they fall from trees (acorns, hickory nuts), are blown by the wind (maple seeds), eaten by birds and animals to be redistributed (berries), or carried on the coats of animals (ragweed).

Take acorns, for example.

Squirrels and other animals depend on them for their winter's food.

In fact, although it is not yet autumn, the squirrels are busy collecting and storing acorns for the coming months. To survive, the squirrels -- and other animals -- need trees' seeds.

So do the trees themselves. Big windstorms have taken a toll on Preservation Parks' trees in the past few years, first with Hurricane Ike in 2008 and then with the derecho June 29. Ice storms have added to that toll. But sure enough, each spring, new saplings spring up to replace what was lost. And the hole left by a wind-blown tree fills in.

Preservation Parks prairies are full of seeds right now, too.

In Blues Creek and the district's other preserves, golden-plumed seed heads wave from atop the Indian grass stems, and bluestem grasses show off their seed-laden tops in a graceful arc.

The birds that live in those prairies load up on the seed. They need it to survive, and so do the prairies themselves.

Each year, Preservation Parks' young prairies fill in and mature with the help of seeds from last year's plants. Park staff and volunteers help, too, collecting seed and using it to expand the prairies and grow new ones.

The prairie habitat is home to many, many insects, birds and animals.

Herbivores, such as butterflies, grasshoppers and sparrows, consume parts of the prairie plants, and they, in turn, are consumed by carnivores, such as snakes, hawks and coyotes. All creatures in the food chain rely on those thriving prairies.

To them, as to humans, autumn is harvest time with its promise of sustenance to carry them through the cold winter.

As the green summer starts to fade into autumn, it's comforting to know the energy used to form new leaves last spring is now contained in that nut, berry or little grass seed.

That is the energy that will be used to create life -- whether in the form of a new tree, an expanding prairie or even a hatchling sparrow -- after fall and winter have passed and spring returns.

Sue Hagan is marketing and communications manager for Preservation Parks of Delaware County.