An Attempt at Prairie Reconstruction

As a backyard prairie begins its second birthday, I anxiously await warming soil temperatures that will signal the growth of what has established and what arrives and germinates in the bare inter-spaces first. I have hope against the dreaded invasive Bermudagrass (Cynodon dactylon), as its runners have thinned severely and rooted less along the total length of the stolons in the young prairie’s germinal empire. But there are the strong rhizomes of Bermudagrass to contend with as well.  The 50+year old African turf here is very well established in some spots.  In others it has gone the way of the too-thirsty St. Augustinegrass (Stenotaphrum secundatum) – died and bequeathed its space to annual broadleaf forbs commonly associated with lawns, or where seeded, natives with a hard heavy seed that are able to gain a foothold in dead turf.

Here’s to hoping year 2 will show positive progress.

Reconstruction vs. Restoration

The two terms are placed under the broad category of “restoration”, which adds to some confusion.  Often, reconstruction and restoration are used interchangeably, but have different meanings.  A prairie reconstruction is the re-establishment of native plant communities on a site where such communities had been eradicated through farming or establishment of lawn.  A prairie restoration on the other hand, involves increasing and maintaining plant communities currently surviving in a remnant prairie site.  Remnant prairies are simply pieces of prairie that escaped the plow.  This does not imply the plant communities there are pristine and in a ‘virgin prairie’ state, however.  All remnant prairies are degraded to some degree and almost always have at least one identifiable exotic species invading their fragile and fragmented state.  In the northern Great Plains, it’s usually Smooth Brome (Bromus inermis), and in the southern Great Plains, it’s Johnsongrass (Sorghum halepense) or KR Bluestem (Bothriochloa ischaemum).


A Review of  Year 1: From Caribbean-grass Lawn to Mixedgrass Prairie

North Central TX – Western Cross Timbers

Site History

In the decades following the Dust Bowl and through the World War II years, this land was a former peach orchard. In my boyhood days, I climbed and played in the only remaining peach tree on this site from that agriculture venture. Following the abandonment of the peach orchard, the land was subdivided and my grandparents were the first to build a house in the new subdivision. This was the 1950s, and green lawns and European landscaping became the rage and the norm; St. Augustinegrass, Bermudagrass, Japansese Nandina, Japansese Honeysuckle, Chinese Privet, and Chinese Holly became the go-to plants.

Over the course of the following decades, cycles of drought and a changing climate dictated only the hardiest of the exotics would remain. Of the two exotic turf grasses seeded, St. Augustine and Bermudagrass, the latter has shown the highest persistence and highest areal coverage increase. The St. Augustine has decreased in population size, lacking the aggressive rhizomatous structure to resist drought as the Bermuda does. Even then, the Bermudagrass has begun to die out in a few areas. Those are the spots targeted for initial prairie reconstruction.

Reconstruction Timeline

September 2013

The proposed initial reconstruction site (approx. 285 sq. ft.) was sprayed with generic Glyphosate at 2% active ingredient to kill actively growing Crabgrass (Digitaria sanguinalis) and Bermudagrass (Cynodon dactylon), and Khakiweed (Alternanthera caracasana).

The soils at the site are a mix of Truce series (moderately acidic to neutral pH fine sandy loam atop claystone bedrock) and a human-made soil of fill sand, from when the site was leveled to support an above-ground pool, leftover construction materials (crushed Austin chalk limestone and residual concrete mix), and decades of lawn clippings that were deposited here.  The bulk of the clippings layer was raked up and hauled off-site.  What remained was removed with light tilling until the site was mostly bare soil.

The initial planting site, post-herbicide application. Note the green of the cool season plants, an excellent fire break.
The initial planting site post-herbicide application. Note the green of the cool season plants.

January 2014

Hand-harvested seed. From L to R: Rough cleaned and mixed, Maximillian Sunflower drying, screened and cleaned seed ready for planting.
Hand-harvested seed. From L to R: Rough cleaned and mixed, Maximillian Sunflower seed stalks drying, screened and cleaned seed ready for planting.

Hand-harvested seed from several counties was thoroughly mixed in preparation for seeding into the area. The site was raked heavily once more to remove remaining thatch, which had built up over the previous decades from the site being treated as a high-maintenance non-native lawn without bagging of clippings. The thatch was hauled off-site and dumped legally. Approximately 5 bulk gallons of rough-cleaned seed (72 species) was uniformly scattered over the site and watered-in for three consecutive days.

Commercial germplasms of native species (e.g. “Haskell” Sideoats Grama, “Lometa” Indiangrass, etc.) were also included in the seeding.  That seed was sown after the hand-harvested seed was sown, as commercial seed is cleaner than hand-harvested seed and often ends up in the bottom of a barrel or bag when mixed with trashy seed mixes.  Commercial seed should be sown before or after trashy seed is sown to prevent settling and uneven distribution within the mixture.

May 2014

A large patch of Redroot Pigweed (Amaranthus retroflexus) dominated the center of the burn unit, comprising roughly 60% of the vegetational area. The species was mostly in flower and easily pulled up, removing much of the taproots. The remains were carefully bagged and thrown away.  The presence of this introduced species indicates the land was in an old-field successional stage in between the years of peach orchard operations and later subdivision development.

The Redroot Pigweed patch. This species is probably the most common non-native Amranthus in North Central TX.
The Redroot Pigweed patch. This species is probably the most common non-native Amranthus in North Central TX.
IMG_0710
Crow Poison

I would like to do a soil seed bank experiment at two other sites in this yard to see what other species besides the common lawn associates are present.  I am assuming very few native species are present in the seed bank until proven otherwise.  The only native forb species that has appeared from the seed bank is Crow Poison (Nothoscordum bivalve).

Greenhouse grown seedlings were planted within the early successional prairie matrix, utilizing the protecting canopies of Common Sunflower (Helianthus annuus) and other annuals. As of this writing, 63 seedlings have been planted, along with rhizome cuttings of Eastern Gamagrass (Tripsacum dactyloides) and Stiff Sunflower (Helianthus pauciflorus). An additional 100+/- seedlings were scheduled to be planted in late June or early July. Another round of larger seedlings (grown in 5” pots) were panted in September, finalizing the planting for the year.

May aspect. A portion of the initial 62 seedling installation is shown.
May aspect. A portion of the initial 62 seedling installation is shown.

July 2014

Growth of all species, including the undesirables, increased greatly due to the early summer rains. The Common Sunflowers had reached over 9ft. in height, and the Crabgrass, though largely unwanted, was realized as a potential annual nurse crop. I expect its coverage to decrease over the years, especially as more perennial species become established and root zones become occupied.  Spot spraying of exotics and other unwanted species continued as needed.

Phase 2 seedling installation.
Phase 2 seedling installation.

An additional 102 seedlings were installed on the eastern and western sides of the intial unit, expanding the perimeter. These were marked with blue pin flags to note second phase of seedling installation. The previous pink pin flags used to mark the initial seedling installation will remain in place through the end of the year to take stock of surviving and non-surviving seedlings. As of July, survival is in the 90% range.

Typical for the month of July in the Western Cross Timbers is a decrease in soil moisture as the May and June precipitation pattern effects fade away, leading into the hot and dry true summer months of July, August, and early September. The blue flagged seedlings were watered until establishment, which took longer than the seedlings installed in the first phase. However, the phase one seedlings were not watered any longer.

backyard prairie
July 5th, 2014.

In the photo above, the young prairie showed its aestival aspect.  Note the two plants with the arching leaves on the left and right sides of the photo above; those plants are Maximillian Sunflower (Helianthus maximilliani), which grew from seed sown in the initial seeding in January.  They flowered their first growing season, a feature not commonly seen in native perennial plants. The large, broad-leaved plant in the foreground is Cup Plant (Silphium perfoliatum), which I grew while working in Nebraska. A fine living memory of a fine state.  Unfortunately, Cup Plant generally flowers in July and August, a period in the Western Cross Timbers of little to no precipitation and drought-like conditions.  I don’t expect Cup Plant to persist here.  Note the abundance of Crabgrass, still.  Better to have that than Bermudagrass.

By the end of August, the Maximillian Sunflowers had grown to 6′ in height and just started to flower.  Other species beginning to flower were Curly-cup Gumweed, Sky Blue Sage, Texas Greeneyes, Big Bluestem and Switchgrass.

October – An Odd Surprise

IMG_3989
Tradescantia occidentalis

For whatever reason – a questionable seed source from a Texas-based seed dealer, a dying plant, or just the right environmental conditions at an odd time, Prairie Spiderwort (Tradescantia occidentalis) flowered.  Whether this was a bad omen of things to come or a hopeful, positive sign of a future reconstructed prairie remains to be seen.  After the flower withered away for the year, I checked the fruits left behind; they were all aborted.

A search in the Flora of Texas Database showed no Spiderwort entries flowering later than August 28 (El Paso Co.).  Likewise, a search through Google Scholar turned up no mentions of fall flowering for the species in Texas, nor does Correll and Johnston’s landmark 1970 publication make any mention of such a late flowering time for the species.

Dormancy

The young prairie entered its first season of dormancy not long after the first cold front of fall roared down the plains on a late October day.  I was pleased with the prairie’s first year, but realized that the absence of Little Bluestem – the chief graminoid the prairies of Texas – left a huge hole in the aspects and feeling of completeness to the young prairie.  This year I will make sure Little Bluestem gets established via seed and greenhouse-grown seedlings.

Observations Made and Lessons Learned

Ideally, an easier way to convert Bermudagrass lawn to prairie is to spend a minimum of one full year using chemical and mechanical site preparation. A minimum 20% glyphosate solution is initially needed to severely set back Bermudagrass, and timing is critical to allow the chemical to achieve maximum kill rate.  More than one application may be needed. Mechanical site preparation will be needed, such as light discing or shallow plowing using sweeps on a field cultivator.

The next best step is to plant seed of wildflowers that have heavy hard seeds and are able to establish rapidly, such as:
American Basketflower (Centaurea americana)
Texas Bluebonnet (Lupinus texensis)
Texas Thistle and Wavyleaf Thistle (Cirsium texanum; C. undulatum)
Partridge Pea (Chamaecrista fasciculata)
Common, Plains, and Maximillian Sunflowers (Helianthus spp.)
Black-eyed Susan (Rudbeckia hirta)
Clasping Coneflower (Dracopis amplexicaulis)
Prairie Coneflower (Ratibida columnifera)

Some slower to establish perennial species can be added as well:
Narrowleaf Coneflower (Echinacea angustifolia)
Engelmann Daisy (Engelmanniana peristenia)
Rosinweed and Compassplant (Silphium spp.)
Stiff Sunflower (Helianthus rigidus)

Most of those species listed above are available commercially, either as selected native germplasms,  (a list of appropriate commercial seed sources for plantings in NCTX can be seen here),  or as part of a “wild harvest”.  Buy wild harvested seeds with caution! Spotted Knapweed (an invasive European weed) is now in Texas because of the use of wild harvested seed.  The species listed above can also be harvested locally by hand – a rewarding and educational experience for those seeding a small area.

Patches of Bermuda and other exotic grasses may routinely appear in scattered locations across the planting site.  An herbicide that is grass selective can be sprayed over the top of the established forbs with no harm done except to the targeted grasses.  No later than the second season, a light discing followed by overseeding of grass species can be done to complete the initial seeding.

Plan to spend 3-5 years of planning, site preparation, seed collecting (or purchasing), monitoring and spraying, and overseeding.  Even then, the work isn’t finished.  Continued overseeding with less common species should be utilized to increase species richness and give power to the dynamics of secondary succession and the prairie matrix, along with the occasional application of herbicides and the re-introduction of fire.

For those used to and expecting a more tame appearance, like the oft used mass plantings of single species groupings, all young prairies will be “weedy” before they are pretty.  Secondary succession won’t let you have it any other way.

Addendum published here.

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4 thoughts on “An Attempt at Prairie Reconstruction

  1. What a wonderful opportunity. I used to have a garden of native plants. I would have loved to dig up the lawn! Not permitted. 😦

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