Restoration and Re‑vegetation for the High Desert Home site

By George Radnovich, ASLA Senior Landscape Architect Partner, Sites Southwest LLC

The High Desert of New Mexico is a very special and ecologically sensitive environment, with its minimal natural rainfall, low density of sustainable plant material, and often highly erosive soil structure. Beyond those influences, human impacts, such as land development, also have consequences. The biological composition and fragile nature of this land makes it difficult at best to restore once it has been disturbed by the building and development process. When I first began to write this article for the High Desert Community, I thought that the most important aspect of this topic would be the process of restoration, the how‑to's of re‑vegetation. In fact without a good primer to help the reader understand the natural evolution of the land, from a disturbed state to a restored ecosystem, it would be difficult to explain the process. Therefore this little treatise includes both a step by step description of the process as well as a catalogue of possible construction methods and a list of seed sources. I should note that some of the construction methods that I describe could require the assistance of a landscape architect or contractor.

The evolution of plants in a desert ecosystem can best be described as a constant struggle to maintain equilibrium within given environmental conditions. It is never static, constantly evolving dependent on rainfall, animal populations, and microclimate. Envision a photograph of a wildflower meadow in your mind's eye. That photograph, with its' beautiful desert wildflowers punctuated with color and glory, is just a snippet of time, as are all photographs. That environment will change the moment that photo is taken. It must be understood that in order to try to maintain that "look", one must sometimes work very hard to encourage these extremely sensitive plants to establish themselves and flourish. After establishment, it may be necessary to re‑seed wildflowers on years that environmental conditions don't provide them with the right mix of water, sun, and protection. Also, wildflowers naturally decline periodically and the homeowner may need to re‑seed or re‑plant vegetation if consistent flowering is desired. This job of recreating ecosystems is what landscape architects and range managers do, although most homeowners prefer a more passive approach. Therefore, in order to achieve some measure of success, one must try to recreate those perfect conditions, which allow the land to restore itself, with our help. These conditions include grading the soil to recreate a natural condition, reseeding to try to attain the density and mix of plants that existed there before the home was built and carefully trying to control erosion and mimic natural conditions.

The restoration of wild lands can be difficult, laborious and often a thankless task. To recreate the native condition requires some knowledge of the restoration process along with ecology, horticulture, biological engineering, and at some level, design or artistic sense. One must have an almost intuitive knowledge of our climate, sod, and response to the orientation of the land. One simple, yet perhaps most important technique includes saving aside the topsoil and associated seed pool left from the grading process where the house will eventually stand. Another consideration might be to try to sensitively site the home on the land, disrupting sod structure, existing grades, and remnant vegetation, as little as possible. Below is the step by step process that the homeowner can use followed by several possible restoration methods.

RESTORATION PROCESS

Step 1. Protection of Undisturbed Land Protection of the extant landscape whether native grass, shrubs, or trees, should be the first order of business. When the home is under construction the potential for the wholesale destruction of that landscape is the greatest danger. Contractors and others may try to drive onto undisturbed land or park under the shade of a tree. These actions may appear to be inconsequential, but nothing is further from the truth‑ When a vehicle is allowed to drive onto the land where native grasses, shrubs and trees exist, they subject that land to the weight of the vehicle, which compacts the soil making it harder to grow plants. They also can cause soil erosion by parking in the same spot regularly and slowly ripping the plant cover away, as well as crushing the roots of trees. Therefore fencing the most sensitive portions of the landscape can save the plants, which invariably saves the homeowner time and money by lessening the amount of impacted land.

Step II Analysis of the Land After taking steps to protect the land's precious resources during construction, the next step of the reclamation process is the initial analysis of the land in order to try to determine the best course of action for successful restoration. Significant points which should be noted include where steep slopes occur, what is the soil make‑up and does it change within the envelope of your land, and are there microclimates which are evident that will affect the growth of plants. The last influence has to do with the solar aspect of the land. That is to say how the sun strikes the land at any given point during the day. Is it in the shade most of the day or do the sun's ray's bathe the land all day long? In most cases there is no existing shade with the exception of small amounts of shade produced by our existing forest of One Seed Juniper, Live Oak, and Piñon. However, the completed building itself creates different conditions producing partial shade for a portion of the day. This step in the process provides a comprehensive picture of the land that can also inform one of the potential for success.

Step III. Select the Best Method of Reclamation Based on all of the information that is collected, the next step is to select the best method or combination of methods with which to attempt this reclamation process. For example, steeper slopes dictate that one of the methods best at erosion control is probably the preferable technique. These could include grading to try to achieve slopes that are less, terracing with rock walls, or using geotextiles to protect the slope. If the site has substantial hardscape like patios and roofs with canales, water harvesting might be in order, or if the site is relatively flat, mulch and crimp or hydromulching may be the best method. Lastly, if immediate gratification is desired, revegetation with plants, as opposed to simply using seed, might be the winning choice.

Step IV: Create a Materials List

In order to truly achieve success at reclamation, matching the existing plant communities and ecosystem with commercially available seed or plants is essential. Choosing from lists that experts have already created is the simplest approach. The High Desert Investment Corporation has formulated one such list (they however do not sell seed). Other mixes are available from seed producers (Plants of the Southwest and others). Creating the list from seeds and plants that are already found on the land is the best but likely the most problematic approach because care must be taken to identify plants and find a source of the seed or plants. This approach takes time and expense because it is custom‑authored, but well worth the effort to bring these disturbed areas back to the natural condition.

Step V.‑ Install the Project

Once the land is analyzed, the method selected and seed chosen, installation is the next step. Choosing the proper season for installation is very important. For the most part it is best to apply seed when the rains occur, with the exception of some wildflowers, which benefit by cold temperatures in winter. Our rainy season is in mid to late summer and is an excellent choice of time because Mother Nature can be used to help germinate and then sustain the seed. In New Mexico we also have a slight rainy season in late spring, April and May. If another time is selected for one reason or another, the application of additional water through irrigation is suggested to help along the germination process. You should be aware that seed installed in the winter may only provide local animal communities with a windfall, which the homeowner finances. I suggest waiting until spring if at all possible. Choosing from the many methods described in the next section of this article may sound overwhelming, so selecting a good landscape architect, designer or contractor is advised. Each of the methods described have very specific application techniques and each can take many weeks and specialized equipment to accomplish.

Step VI. Managing the Land

Acting as the steward of your land is the optimum way to achieve success with revegetation projects. This means paying attention to natural processes, following the weather, and noting growth rates. Perhaps the largest management issue is to mitigate water and wind erosion. Cures for this dilemma include protecting the slope, building check dams to lessen the velocity of drainage water, and re. mulching. If animals are a Problem, try to control them by protecting the seed with mulch or perhaps burlap. Watch over your project to try to control the many maintenance dilemmas, which may arise: if you can't pull the inevitable first successional plants (such as Russian Thistle) out by the roots, mowing, rather than chopping them is a good technique. Mowing them prevents seeding from occurring, but allows them to act as green mulch for the germination of seed, a positive feature. Chopping destroys small seedlings coming up below larger weeds. If rain is not forthcoming for one reason or another, you can irrigate the reseeded area. However, many native seed requires almost as much water as non‑native seed to germinate. Therefore try to keep the soil evenly moist until germination occurs (at least twice per day for about two to three weeks).

RESTORATION METHODS

Now that you have some understanding of the basics of installation, I have included below a description of some of the methods, which might be used to try to restore the land to a native and healthy condition. As I mentioned in the previous section, protecting the land from disturbance is highlighted with any method chosen. Second most important is to save aside the topsoil which is inevitably scraped from the land during building construction which should then be re‑applied as part of the mulch with any of the methods described below. I would like to point out that many of them are best left to the professional contractor because of the specialized equipment which is necessary, but I have included techniques that the homeowner can also use.

0 Broadcast or Hand Applied Seed ‑ After the land is turned, disked, or filled and the seed bed is prepared one can simply broadcast the seed by hand over the area to be seeded using the rates suggested by suppliers. After the seed is sown, it is also a good idea to rake it into the soil then cover it with a mulch to protect it. Mulches, which can be used, include Hay, Wood Mulch and Wood Fiber. Then either hand water or let Mother Nature do the work by performing the seeding during the rainy season.

Hay Mulch and Crimp Method ‑ Again, after the ground is broken by filling or "disking (most contractors possess a plowing implement with disks outfitted, the homeowner can use a rototiller), and the seed is applied, hay, preferably from native grass, is spread and then crimped or thrust into the soil. The hay can be crimped with a shovel or the more mechanical method of using a disc apparatus on a tractor. This crimped hay creates shade for the seed, it breaks up the soil and applies organic material, it sometimes has seed attached, it limits erosion during the germination period, and it forms a wick that channels water down into the soil.

Rock Wall ‑ When slopes are steeper than 3 feet of rise to I foot of fall it is advisable to terrace the slope to lessen it. If one decides to terrace, a Chacoan style or "dry‑stacked" rock wall can be used. If the wall is too high (generally higher than 3 feet), it may be necessary to use concrete or concrete block to retain the soil. Concrete block walls cannot be used outside of the building envelope within The High Desert Community however. Another approach is to "armor" or fine the slope with larger (up to 12") rock, preferably rock that is natural in color and texture to hold the soil in place at a slope.

Gravel Mulch ‑ Another choice which is similar to larger rock set on a slope is to add a small percentage of gravel to the soil (30‑50%) itself or to add a loosely spread and single layer of gravel to the surface of the soil. However, this does not mean a solid gravel mulch, which is unacceptable at High Desert The size of the gravel can vary based on the orientation of the land, larger gravel's are more useful on sloped land to help hold down erosion of the soil, smaller gravel's can be used on flatter terrain. This approach allows condensation to form under the gravel layer, which adds to the water holding capacity of the sod, helps germinate seed, potentially provides shade and a cooler ecological niche, and holds down erosion. If this method is chosen, soil colored gravel should be used and only, as stated previously, not covering the land with a solid sheet.

Water Harvesting and Soil Imprinting ‑ If water can be added to the mix, the success ratio for restoration can be greatly enhanced. For this reason you may want to try redirecting drainage water, perhaps from a canale, a patio, driveway, or other impermeable surface, to seeded beds to add to the soil's ability to procreate plants. The "drainage ways" or swales that are created should be roughly graded and not smooth to slow water velocity, and help better capture what little moisture that is available. It is truly amazing what a small swale can accomplish! Along the swale, small earthen dams can be used to slow down the water or hold it in place so it can seep into the soil and nourish the roots of plants to increase vegetative self‑sufficiency. Sod imprinting is another method that harvests water from natural rainfall, which may be useful. Soil imprinting simply imprints the sod with indentations that hold water when it rams, like many little reservoirs. These indentations or imprints are either dug with a shovel or an indentation is created with a roller. Seed is then applied and mulch is applied over that. Water harvesting is perhaps the most efficient use of rainwater available to us in the southwest. If the grading is especially steep or complicated, or if there is a substantial amount of water running off of impermeable surfaces, the homeowner may want to seek the assistance of a competent professional engineer or landscape architect because your grading/drainage plans may need modification and reapproval.

Geotextile and Fiber Mat ‑ Geotextiles are those odd looking carpets that are sometimes used to line heavily sloped areas. These mats look like evaporative cooler pads because they are made of similar materials. Aside from the obvious look which many think is a bit incongruous, these methods are difficult to install and even more problematic later. Weeds often pop up through these mats and sometimes water erodes under them. From an aesthetic standpoint these fibrous mats may be a poor choice, however, from an environmental point of view they are typically made with a renewable resource using the discards of timber industry's, which adds to their sustainability.

Hydroseeding and Hydromulching ‑ This method of re‑seeding is by far the easiest, if the specialized equipment to perform the operation is available, however it's success has been spotty. The approach is to add seed and fibrous wood mulch to a watery slurry, which is then sprayed onto the surface of the land. It is often pigmented green. This is done, not to help envision the way the grass will look when it grows, but rather to help the contractor see where it has been sprayed so the applicator doesn't get mixed up and spray an area twice. After the seed/mulch slurry is applied, the area is again sprayed with a surface application of what is called a "tackifier". This material is a glue of sorts, which holds the mulch in place and attempts to control soil erosion by wind or water. A contractor, who has the equipment, because it takes a specialized tank and nozzle to hold the slurry and spray it, is perhaps best qualified to attempt this approach.

Revegetation ‑ This approach combines re‑seeding with adding small plants such as Chamisa, Apache Plume, Four‑wing Saltbush, and some grasses which are then left to they're own devices to survive. Using any of the methods described within this article, small plants can be added to the land after reseeding is accomplished. The plants should be placed where water is likely to collect, they should be no bigger than small 2" pots and they should only be plants, which are native to the area and hopefully not appetizing to animal communities. The reason that small plants are suggested is that they are easier to establish without irrigation. If irrigation is added, larger plants can be used. Water holding materials such as porous ceramics polymers or cellulose treatments such as "Driwater" can also be used to help this approach succeed. This method has the advantage of having the most immediate gratification.

As I mentioned above many of the techniques that I have described within this article require specialized equipment and very specific procedures that the homeowner may not want to attempt. In those cases soliciting the help of a competent landscape architect or designer may be suggested along with a contractor, and please don't forget that any plan modifications must be brought to the attention of the High Desert New Construction Committee (NCC).

Our desert ecology is one of the most drought tolerant and strongest in the world, while at the same time very sensitive and fragile to impacts. This seeming ambiguity is what makes it so stark, beautiful and some would say, special. Because of this imbedded genealogy, it is not quick to regenerate, easy to install or always successful, but with the proper approach it can be rewarding.

Possible Supplies of Seed and Other Materials

Plants of the Southwest Albuquerque Retail Store 6670 4" Street NW Albuquerque, NM 87107 (505) 344‑8830

Plants of the Southwest Santa Fe Retail Store Agua Fria, Rt. 6 Box IIA Santa Fe, NM 87501 (505) 438‑8888

Curtis & Curtis, Inc. Star Rt. Box 8A Clovis, New Mexico 88 101 (505) 7624759

Granite Seed 1697 West 2 100 North Lehi, Utah 84043 (801) 768‑4422 or (801) 531‑1456