Elk graze in the dune grass as fog rolls into the shore at Fort Stevens State Park.

As the weather has improved in recent weeks, regular strolls along trails and beaches have become decidedly more pleasant.

On the Long Beach Peninsula’s Discovery Trail, I hear the songs of white-crowned sparrows off in the shore pines, and the seashore lupine is producing lavender sprays of flowers. It’s nice to be able to walk along the boardwalk and see the ocean without the frigid air.

By this time of year, coastal grasses on both sides of the Columbia River have come back in full force after a winter of dormancy. Their long, slender leaves fill the dunes, and every year they advance further toward the water — a few intrepid scouts at first, but in later years these are followed by increasing masses of vegetation.

Areas that were bare when I moved to the area eight years ago are now covered in thick green swathes.

It wasn’t always like this, though. If you had looked upon these shorelines when Lewis and Clark ventured out in November 1805, you would have seen vast ranges of sandy dunes, pockmarked perhaps with a little dry vegetation, but otherwise open.

In the summer, those dunes would have been populated with small patches of sand verbena, sea rocket and a uniquely blue-tinted grass with wide leaves, among which nested shorebirds and other wildlife.

Many people are surprised to learn that endless waves of grass are not the natural state of this shoreline.

On some East Coast beaches, grasses have dominated dunes for thousands of years, but West Coast habitats are different. Here in the Columbia-Pacific region, the sandy areas have been largely open, with dunes that shift and travel with the wind and waves, and plants that have evolved to live in a mutable environment.

All that changed once settlers built houses and businesses along the beach. People didn’t want sand in their homes, nor did they want to have to spend time sweeping or shoveling it away.

So, a little over a century ago, two invasive kinds of grass were introduced to lock the dunes down: American beach grass, which is native to the East Coast of the United States, and European marram grass, which lines the shores of the North Sea and the Mediterranean.

Both species grow wide monocultures that allow few other plants room to breathe. This is very unlike the native American dune grass, which grows in small patches with plenty of sand in between.

An ecosystem that was once dependent on open ground for other plants to thrive and wildlife to nest quickly became choked by invasive grasses, which can now be found along most of the Northwest’s coastal shoreline. The grasses have even begun hybridizing to create a third aggressive population.

This imbalance, while benefiting humans, has been troubling for wildlife. The native dune habitat is now limited to a narrow band between the open beach and the ever-encroaching grasses.

Native plants are becoming scarcer, with pink sand verbena being particularly affected. The western snowy plover and the streaked horned lark, both of which need quiet areas of open sand to nest, are similarly threatened.

In recent years, there has been growing interest in restoring dune habitat. Intensive efforts by the Willapa National Wildlife Refuge have seen a large section of the coastline near Leadbetter Point State Park bulldozed to bury the invasive grasses.

Meanwhile, native species of grass are being reintroduced — and western snowy plover activity has been on the rise in the years since that restoration began.

For those curious about how to tell invasive and native grasses apart, whether for habitat restoration or just their own curiosity, the easiest way is to look at the leaves.

The two invasive species have slender, yellow-green leaves, composing much of the mass of vegetation on the dunes. But look closely, and you may see patches of wider, blue-green blades, looking like bundles of turquoise ribbons growing out of the sand.

These are Leymus mollis, or American dune grass, and they often have a glaucous white film over them, similar to that sometimes seen on cabbage leaves. Later in the year, once all three species have gone to seed, the seed heads of the invaders tend to be longer than those of the native grass.

Local beaches are likely stuck with nonnative grasses, but restoration projects can be the difference between survival or not for plants and animals that need the open dunes.

With luck — and effort — shorelines in the Columbia-Pacific will continue to be home for these species amid a sea of nonnative grass.