Tuesday, November 28, 2017

Farm Bulletin: Our Land of Tule and Cattails

You might ask why a farmer would devote nearly half his acreage to support a wetland rather than filling it and growing more crops. Contributor Anthony Boutard of Ayers Creek Farm has his reasons.

It is hard to muster much sympathy for nutria, with their beady little eyes and humorless demeanor. Then again, the poor dears spend the summer quietly feeding and building among the tule and cattails—unobserved bliss in nutria terms. Then the water level rises and migratory water fowl descend. The geese and cormorants haze them mercilessly and defecate all over their tussocks, and the eagles eye them hungrily. They cluster together, four or five, to avoid being picked off as prey. This morning the water is very high and a shard of sympathy is felt.

Patches of tule at the south end of the wetland.

Ayers Creek Farm has nearly 80 acres of ground suited to the production of crops. The remaining 64 acres include a 40-acre open wetland, 20 acres of oak savannah and some swales of green ash and hawthorn. A little over half the farm is a managed landscape, a little under is largely unmanaged. It is hard to imagine the farm without its two hemispheres. For us, a highly productive square of farmland would be a dull place indeed without the messy exuberance of the wild areas bleeding into our efforts at an organized ecology.

This spring we were approached by a botanist volunteering for the UFWS [U.S. Fish and Wildlife Service]. Ginny Maffit was curious about our bottomland which, she had heard through the grapevine, was a fine example of an undisturbed wetland community. In response, we explained the process whereupon it became “undisturbed,” a term the nutria would dispute. Several notes, edited and merged, describe how the wetland developed and matured.

* * *

Our wetland, about 40 acres in extent, was cultivated until 2002. It is mostly Labish muck*. Because it is outside of the local dike system, it tended to flood early, making harvest difficult. For many years, the "Wapato Improvement District" managed water level in the valley bottom for onion growing. Over time, onion growers died off and their families eventually sold the various holdings to the U.S. Fish and Wildlife Service for a Wapato Lake refuge.

Wapato or arrowhead flower.

As onion-growing petered out, pumping patterns within the dike changed, increasing the challenges. We asked TVID [Tualatin Valley Irrigation District] to let the water rise as security measure for the other irrigated fields on our property, providing a buffer capacity. We fretted initially because many people told us we would end up with a thicket of reed canary grass. Several people identified a certain piece of property within the lake, owned by a federal agency, that turned into a canary grass wasteland. We had never seen it, but heard about it a lot. On the other hand, along highway 47, south of milepost 22, there is a small patch of wetland that we had always envied because of its vegetative structure.

We poked about the government websites researching wetland restoration, but the approach always seemed to be heavy-handed and inconsistent with our appreciation of natural succession. We are organic farmers by disposition. In addition, we have confidence in the way natural systems can repair a site. The first few years a low, rhizomatous grass took over the low areas on the site, dominated by Labish muck. And, as predicted by Gaston's Greek chorus anticipating another tragedy, reed canary grass quickly occupied the Wapato silty clay soils, a foot or two higher in elevation but still flooded from October through March. Another year or two passed, and we noticed the vegetation was starting to shift. Through the thick thatch of the "witch" grasses, we saw new plants emerging. In the reed canary grass, several different woody plants established themselves, including roses, ashes, hawthorns and spirea.

A cinnamon teal nest.

By 2007, the bottom had developed a remarkable mosaic of vegetation types. Tule, bulrushes, cattails, wapato, sedges, rushes and various grasses were all represented in bands and islands. The hardwood shrubs and trees are now establishing themselves along the fringes. It is a beautiful example of a natural wetland succession, predominantly native in composition. Now the Chorus’ chant can praise the natural qualities of the wetland.

Yes, there are some non-native species, especially along the eastern fringe. However, the bulk of the wetland represents as fine a native wetland as you can find, resulting from a simple, just-add-water approach. Cost us next to nothing in treasure or effort, and has provided endless pleasure. There is a rich assemblage of nesting birds. The last two years, we have had between 20 and 65 white pelicans foraging in the shallows during the spring. One sultry evening this summer, we spent an hour watching a yellow breasted chat as it bounced from one perch to another. At the south end, there is a big patch of tule where the marsh wrens build their softball-sized and shaped nests. Another reason to tarry on the way to nowhere in particular.

Drained wetland systems that have been cultivated for decades do not have much to contribute vis-a-vis their seed bank. So how did all these plants find their way to our swampy hole? Wetlands are generally connected via water courses and/or fauna (birds and mammals), and these provided the seed source. Growing up in New England, we are familiar with shifting wetlands following a move-in by beavers damming a stream, necessitating a portage. Within about the same space of time as our wetland development, these ponds would fill in with the species typical of wetlands along the water course.

Wapato or Arrowhead growing in clumps.

Our wetland is illustrative of this mechanism. As we are outside the dike, we received seeds and other propagules from the diverse, vestigial patches of the original Wapato Lake that fringe the outer wetland fragments that have never been cropped. Not of great extent or particularly interesting to most, but of immense importance to holes. As the system drains in late winter, the water flows upstream from these patches, as well as downstream, so we get a nice dose of propagules from these areas. Because it is a case of mass selection rather than a managed planting, the various species and assemblages find their appropriate place in the mosaic of soil types and water depths. Planted “restorations” in our estimation always look planted, a forced pattern discordant to the eye.

We see our patch of wetland as a grow-out of the Wapato Lake's historic flora, maybe not complete in terms of species but functionally whole. It provides a summer home for the bitterns, grebes, rails, marsh wrens and cinnamon teal and other ducks. We have a large and diverse population of dragonflies as well, and they spend the summer hawking among our crops.

All-pelican production of Swan Lake.

Among the birds is a tundra swan that has been there since January or so. It was probably injured rather than uninspired to take flight, however it an observation based on sedentary behavior rather than seeing an injury. Otherwise very healthy, no signs of distress. It continues to stretch its wings, moves well on land and water, a nice natural water feature. This autumn it has been joined by 16 other swans, including two grey cygnets. This is the second year we have hosted white pelicans, one evening we counted 65, though typically they numbered around 24. These huge, ungainly birds are spectacular when they come in to land. The swan, unimpressed by their magnificence, stayed apart, and engaged in some agitated head bobbing when they came close.

Over that last four years the wetland, formerly leveled for agricultural use, has developed a distinctly hummocky aspect. The architects are the nutria, regarded as vermin by most farmers and used as target practice by local kids. These hirsute engineers create channels and pools so they can move about the wet areas safely and efficiently, their own variation of Venice's canals. There may be muskrats as well, but the nutria are the dominant rodents. Walking the wetland's fringe, it is apparent that the channels of the rodents are extending the wetland vegetation in the areas dominated by the reed canary grass. Wetland plants are well adapted to herbivory. In fact their growth is generally stimulated by the activity, as is evident by the work of the nutria. Native Americans observed and understood the stimulatory effect of their harvest, and maintained vigorous beds of wapato. That is why we are sanguine about harvesting some of the corms for our restaurant accounts.

* Muck is a high organic content soil type formed from former lake bottom deposits. “Labish muck” is a series found in the Willamette Valley. The type was first described from the remains of Lake Labish in the Salem area. The muck of Lake Wapato shares its characteristics, so it falls into that soil type.

All photos by Anthony Boutard.

No comments: