The trees that were planted on 9 acres on the edge of David Force Park in Ellicott City this week are only a few feet high; small evergreens and spindly seedlings that look more like twigs stuck upright in the ground.

But with nurturing and good weather, the Howard County Department of Recreation and Parks' latest plantings - 6,625 new trees planned on 13 publicly owned sites by Thanksgiving - will thrive.

"We concentrate on stream areas more than anything else," said Mark Raab, superintendent of the parks department's natural resources division. "It is the most benefit for the dollars spent."

Those dollars come from developers through a system of state and county laws intended to offset the devastating effects new building projects can have on natural landscapes.

Trees are needed to provide habitat for animals and birds, to improve air quality, and, most important, to filter contaminants as ground water travels to streams and then to the Chesapeake Bay.

With those benefits in mind, state legislation was passed in 1991 that requires counties to produce plans to protect trees during development and replace those that are lost.

Howard County complied with its forest conservation plan passed in 1993.

The Howard law requires developers to protect trees already standing on building sites. If too many trees are cleared or if a site has few trees to begin with, developers must plant new ones on site.

In some cases, developers may plant or preserve trees elsewhere.

If none of these options are feasible, the county Planning Department can accept a fee from developers in lieu of planting.

(The county generally accepts the fee rather than trees from developers when the number of trees involved is small and when planting on county-owned land seems more appropriate.)

That is where the county parks department comes in.

In fiscal 2002, which ended in June, the parks department used $313,632 of fee-in-lieu funds to plant 24 acres with trees, according to a report of the county's environmental steering committee.

Not counting this year's projects, 36,591 plants have been placed on just over 100 acres using this type of funding since 1996, the natural resources division reports.

Another 100 locations proposed for new trees have been identified for coming years.

"Now that there is a penalty, a significant one, I think developers are trying a lot harder to keep trees," said McLaughlin. And where it is not possible to work on site, "at least now there is a revenue stream for getting a proportion of those trees replanted," she said.

"It is a pretty pragmatic way of implementing forest conservation," said Tom Ballentine, director of government affairs for the Home Builders Association of Maryland.

"It is more beneficial on the whole than ... forcing planting on an area that [is] not particularly well-suited," Ballentine said.

The fee-in-lieu provision is included in the state guidelines. And while counties and cities prefer to encourage conservation and replanting on developed sites, many Maryland communities are taking advantage of fees when a developer exhausts other options.

Baltimore County, Anne Arundel County and, more recently, Harford County, have developed programs to take advantage of the funds. Carroll County does not accept fees, Baltimore City does only occasionally and Montgomery County says it could, but has never needed to.

It depends on how much staff and resources an area has to take on plantings, said Marian Honeczy, state forest conservation program coordinator.

There are also local issues, such as the number of trees standing, the rate of development and the availability of public land in need of plantings.

The continuing severe drought almost derailed the county's reforestation plans for this year, said Raab. The department held out past its usual October planting season until recent rainfall persuaded officials to give it a try.

Up to two years of preparation precedes the first shipment of plants. That includes studying water availability and soil types to choose plants - all native species - that are well-suited for the location.

The department may also mow areas to keep the invasive species under control at first, even though the goal is to let the area grow wild.

Another important part of preparation is notifying the community through letters and meetings about plans for plantings.

"Most people believe natural resources [department] land is somewhere else," said Dan McNamara, natural resources operations manager. It requires education to explain that strip behind their property is it.

Indeed, at the David Force site, brown stakes marking the park boundary were placed several feet into areas that neighboring homeowners were mowing regularly.

Kate Powell and her family were alarmed to receive a strongly worded notice that they were mowing too far onto county land and could face fines or court action.

"I just wish they had been a little more sensitive about informing us," said Powell, 33, a stay-at-home mother.

David Force Park borders their land, and the Powells are sorry to lose some of their lawn space. But they also believe they will enjoy seeing more trees, and they prefer forest to development behind their home.

"I think once it grows, it will be nice," Powell said.

Once the trees are in the ground, "the biggest mistake for a reforestation site is to not stick with it and maintain it," McNamara said.

Rodents and deer eat bark, which can be fatal to trees. This year, the department is covering the trunks of the growing trees with plastic mesh to keep out hungry animals.

An even bigger danger is invasive plants taking over the habitat, said Raab. Foreign shrubs, vines and trees have no natural predators and grow quickly, choking out the desirable plants, he said.

Years ago, conservationists could leave an area alone and it would grow fairly successfully, Raab said, but that may never happen again. In the future, "the invasives in some areas are going to make the deer (problem) look minuscule."

Raab says the natural resources division is well-suited to take on all the challenges of reforestation on public land, because they have a vested interest in seeing it succeed.

Still, when he sees areas planted years ago, with tress growing tall and plentiful, Raab says, "I can't believe we really did this."