TREE SUCCESSION

Location in Park

Location in Park

Tree Succession

Like many of the unmown areas of Fort Williams Park left to develop naturally, this small site is a good example of secondary succession, an ecological process by which the makeup of plant species evolves over time after some kind of disturbance. In New England, most open sunny sites are initially colonized by fast-growing annual weeds and grasses, and then by sun-loving herbaceous plants. Over time, these plants alter conditions that support pioneering shrubs and fast-growing, smaller, short-lived trees. Biodiversity is especially rich during this early stage, supporting a wide variety of insect, bird and animal species. In late secondary succession, these shade-intolerant shrubs and trees are gradually replaced by slower-growing, larger trees that are better adapted to the modified habitat. Under the canopy of these long-lived hardwood trees, a shade-tolerant understory establishes itself.

Our objective for this site’s vegetation is to allow natural succession of native species to continue by controlling invasive plants that negatively impact this process. Site improvements include renovation of the existing stacked stone retaining wall.

Tree Succession

Tree Succession

Tree Succession in Autumn

Tree Succession in Autumn

Historic Remnants:

  • Stacked Stone Retaining Wall (ca 1907): Adjacent to the demolished Double Barracks
Stacked Stone Retaining Wall

Stacked Stone Retaining Wall

Please visit the Park History page for more information about Fort Williams’ military past.

Featured Problematic Plant: common buckthorn (Rhamnus cathartica)

Introduced from Europe as a hedge plant, common buckthorn is a large, deciduous shrub or small tree growing in open woods or sunny thickets, with oval leaves, inconspicuous yellow-green flowers, shiny black berries in late summer, and a single sharp spine at the tip of most stems.

Many mammal and bird species feed on buckthorn berries, widely distributing their seeds, and they are very tolerant of shade and moisture. Like Asiatic honeysuckles and many other invasive plant species, buckthorns leaf out early in spring and retain their leaves late into fall, giving them an advantageously longer growing season than most of our native species. They also alter soil chemistry to the detriment of native plants.

Featured Beneficial Plant: white birch (Betula papyrifera)

Also called “paper birch,” white birch is a cold-climate pioneer species that grows throughout Maine, often in pure stands but typically mixed with other tree species at the forest’s edge. Thriving best in rich, moist soils, paper birch also grows in dry, sandy soils, but it does not adapt well to drought or prolonged periods of high heat.

Admired for its delicate, graceful form and moon-white bark, white birch is relatively short-lived and doesn’t compete well with other tree species, eventually being overwhelmed by trees better adapted to shade. This process is under way here in the Tree Succession site, as white pine, red spruce, white ash and red oak are beginning to rise above many beautiful birch clumps.

Many bird species forage birch catkins and use the exfoliating bark as nesting material.

Common Buckthorn (with autumn fruit)

Common Buckthorn (with autumn fruit)

Paper Birch

Paper Birch

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