ROCK SPRINGS, Pa. — Jim Walizer planted his first riparian buffer two decades ago and has been a conservationist and clean stream advocate ever since.

Walizer is a semi-retired farmer who was one of several guides for a 45-minute tour of the riparian buffer demonstration plot last week at Penn State’s Ag Progress Days.

The buffer plot has trees in zone one, shrubs in zone two, and native grasses and forbs in zone three. With one exception, the plot has everything necessary to qualify as a riparian buffer under various state and federal programs.

The exception? It doesn’t have a stream.

While it lacks an actual run, crick or river, the site of the university’s Russell E. Larson Ag Research Center here does have 2,000 acres of just about everything else that’s important to Pennsylvania agriculture.

The streamless demonstration plot exists to acknowledge the important role buffers play in the state’s ambitious plans to clean up its waterways and contribute fewer pollutants to the Chesapeake Bay.

The state Department of Conservation and Natural Resources recommends a buffer at least 35 feet wide, including at least Zones 1 and 2 described below:

• Zone 1 — The first 15 feet from the stream edge, planted with native trees and shrubs, no harvesting allowed.

• Zone 2 — 20 to 35 feet from the edge of Zone 1, planted with fruit and nut trees and shrubs, non-mechanical harvest allowed.

• Zone 3 — From edge of Zone 2 out another 50 to 100 or more feet, planted with woody florals and forbs, including biomass crops. Mechanical harvest is allowed.

Planting establishment and maintenance:

• Zone 1 — Herbicide use is allowed during site prep and twice annually for maintenance. Planting density will vary by species, by site characteristics, and by landowner and vendor preference.

Acceptable planting methods include container stock, bare-root seedlings and direct-seeded plants.

• Zone 2 — The herbicide use requirements are the same as in Zone 1.

Container stock is preferable to minimize the time needed to start producing income.

The zone width may vary based on hydrology, soil type and other conditions.

• Zone 3 — The requirements are similar to the other zones, but mechanized planting and harvesting are permitted.

There are no buffer police patrolling the state’s stream-blessed farms, but the guidelines — in addition to meeting grant requirements — are designed to meet environmental needs, said Timothy Cole of the Department of Conservation and Natural Resources.

The guidelines have changed over the years.

At one time, livestock could be used to control weeds under the forested canopy.

But a number of farmers considered weed control to mean unlimited Holstein access, so that guideline was scrapped.

On the other hand, Zone 2 harvesting guidelines have been relaxed to allow hand picking of such crops as hazelnuts, elderberries, pawpaws and raspberries.

One presenter said he’d seen a quart of elderberries selling for $9 at a local farm stand.

Timbering is also allowed in Zone 2, but the 10-to-20-year wait for a harvestable log means that’s a long-term investment.

Walizer, the boots-in-the-field presenter, isn’t convinced that buffer harvests are profitable enough to justify the labor involved. But he is nevertheless a fervent buffer buff.

Good buffer management helps keep plant nutrients in the soil and soil in the field.

A healthy stream provides shade for large invertebrates like hellgramites, crayfish, snails, toe-biters, leeches and other critters that get eaten by the small fish, which get eaten by the big fish, which get eaten by herons and humans.

Walizer favors hardwood species for riparian buffer streambanks.

A maple, for example, with its copious canopy and its whirlybird seed pods provides plenty of fodder for those water-dwelling invertebrates at the bottom of the food chain.

Hardwoods, in fact, are just about requisite for anybody who wants to encourage a good trout stream, he said.

So if you’re thinking about planting a riparian buffer, be sure to include some maple, sycamore, locust or the like in your streambank planting.