INTERSEEDING AND TRANSPLANTING TO ENHANCE SPECIES COMPOSITION

Richard Stevens

ABSTRACT

Shrub, forb, and grass species can be interseeded and transplanted into annual and perennial grass and forb communities to improve the nutritional quality of forage and lengthen the season of grazing use. The addition of shrubs and {orbs by interseeding and transplanting to grass and forb communities increases plant community diversity, which should increase the diversity of animals as well. Herbicides or scalping can be used to eliminate competing plants in and near the seeding and transplant­ing area. When transplanting, proper handling of plant materials is essential to success.

INTRODUCTION

Within the Intermountain West, vast areas are domi­nated by fairway crested wheatgrass (Agropyron cris­tatum), standard crested wheatgrass (A. desertorum), cheatgrass (Bromus tectorum), and other introduced and native perennial and annual grasses. Hundreds of thou­sands of acres are also occupied by various shrub and forb communities with low productivity.

Shrub, forb, and grass species have been successfully established through interseeding and transplanting in perennial and annual communities and on prepared and disturbed sites.

Interseeding and transplanting adapted palatable and useful shrubs and forbs into less-productive communities or monocultures can improve the nutritional quality of forage and lengthen the season of grazing use, especially later in the year when grasses are dry and crude protein values are low (Rumbaugh and others 1981; VanEpps and McKell 1978). Additional benefits include improved species richness, community diversity, esthetics, cover, forage production, and soil stability. Because monocul­tures of any species are poor habitat for most wildlife, im­proved diversity will result in an increase in the diversity of birds, mammals, reptiles, and insects found in the com­munity (Reynolds 1980).

Selecting plant materials adapted to the planting site is important for any successful revegetation program (Penrose and Hansen 1981; Rehfeldt and Hoff 1976; Stevens 1981). Selected species must be able to establish,

Paper presented at the Symposium on Ecology, Management, and Res· toration of Intermountain Annual Rangelands, Boise, 10, May 18·22, 1992.

Richard Stevens is Project Leader and Research Biologist, Utah Divi· sion of Wildlife Resources, Great Basin Experiment Station, Ephraim, UT 84627.

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persist, and maintain themselves and produce seed. This does not mean that the transplant or seed needs to come from or near the proposed treatment area, but it does mean that they need to be adapted to site conditions.

INTERSEEDING Interseeding of compatible shrubs, forbs, and grasses

into plant communities with low productivity or little di­versity can provide a means for improving habitat, for­age production, forage quality, species richness, commu­nity diversity, and soil stabilization. A number of shrubs have been successfully interseeded to improve big game, small game and nongame, and livestock ranges (Barnes and Nelson 1950; Monsen 1980a, 1980b; Plummer and others 1968; Stevens and others 1981). Interseeding has been used to establish desirable species in closed commu­nities of cheatgrass (fig. 1) and mountain tarweed (Madia glomerata) (Arizona IRTS 1969; Giunta and others 1975), and other annual and perennial communities (Derscheid and Rumbaugh 1970; Lang 1962; Nyren and others 1980).

Interseeding can provide an attractive alternative to complete community alteration caused by seedbed prepa­ration or when the purpose is to modify rather than re­place a plant community (Jordan 1981; Vallentine 1989). To effectively interseed into existing annual and peren­nial communities, competitive plant material within or near the seeded area has to be temporarily eliminated. Interseeding can also occur in conjunction with other seeding on prepared seedbeds.

Figure 1-Six-year-old fourwing saltbush plants that were interseeded into a cheatgrass community.

This file was created by scanning the printed publication.Errors identified by the software have been corrected;

however, some errors may remain.

Interseeding in Conjunction With Removal of Existing Vegetation-Two economically effective meth­ods of removing competitive vegetation are use of herbi­cides or scalping. These methods have to: (1) be wide, and in the case of scalping, deep enough to remove or kill all seeds and rhizomes of competing vegetation; (2) allow seeded species to become established before competing vegetation rein vades; and (3) result in scalps with shapes and sizes that will collect moisture (Jordan 1981; Stevens and others 1981).

Competing vegetation can be killed in strips or in spots with appropriate herbicides (fig. 2A) (Eckert 1979; Nyren and others 1980; Stevens 1985a). The sprayed strips or spots can be seeded with fall drill or broadcast seedings (fig. 2B). These techniques allow seeding to occur in the A most fertile soil and in association with litter that can help protect seedlings from temperature and moisture extremes (Stevens 1985b).

Competing vegetation can be mechanically removed with various types ofpitters, scalpers (Giunta and others 1975; Jordan 1981; Larson 1980; Monsen 1980a,b; Nyren and others 1978; Schumacher 1964; Stevens 1979; Vallentine 1989; Wright and others 1978), and with rototillers (Smoliak and Feldman 1978). The Sieco fire plow and Hansen Scalper are the most commonly used scalpers (Larson 1980).

The width of the scalp or pit depends on the density, vigor, and growth form of major species in the existing vegetation, the species being interseeded, and site condi­tions. Care must be taken to ensure that the most fertile surface soil is not removed (Stevens 1985b). Drier sites require wider scalps because of increased competition for moisture. On arid sites, summer fallowing may be re­quired to minimize competition and maximize moisture availability (Bement and others 1965). Scalps made on the contour with cross dams can catch and hold additional moisture from snow and rain (Branson and others 1962; Stevens 1978). The additional moisture enhances chances of seedling establishment and subsequent plant growth. Interseeding shrubs into cheatgrass brome, Giunta and others (1975) found that shrub seedling establishment was superior in 61-cm (24-inch}-\vide scalps as opposed to 10-cm (4-inch), 20-cm (8-inch), and 42-cm (16-inch)-wide scalps. When interseeding native shrubs into established crested wheatgrass, VanEpps and McKell (1978) found that the best scalps should be 101 em (40 inches) wide, with optimum spacing being 152 em (60 inches). This study also monitored seedling establishment in intermedi­ate wheatgrass (Agropyron intermedium) 1, 2, 3, and 4 years after seeding. The widest scalps, 76 em (30 inches) wide and 29 em (9 inches) deep, resulted in the most plants per 30 em (12 inches) of scalp. Established plants in the wider scalps also were the most vigorous and larg-est. They also began flowering sooner than plants in the narrower scalps.

Seeding generally occurs in conjunction with scalping. This can be accomplished with a Hansen Browse Seeder or Thimble Seeder attached following the scalper.

lnterseeding in Conjunction With Other Seeding Techniques-Shrubs, forbs, and grasses can be seeded separately, in conjunction with, and simultaneously with other species. Interseeded species can be seeded with

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B

Figure 2-Strip of intermediate wheatgrass sprayed with Roundup (A) and seeded (B) to various shrubs and forbs.

seed dribblers and thimble seeders (Larson 1980) mounted on crawler tractor tracks at the same time broadcast or drill seeding is occurring (fig. 3). As the tractor track moves forward, seeds are dropped onto soil ahead of the moving track. The tractor presses the seed into the soil, making a firm seedbed. This technique can leave rows of seeded species wherever the tractor travels.

Figure 3-Fourwing saltbush plants seeded through seed dribbler mounted on crawler tractor that was chaining pinyon and juniper trees.

It is important to only seed compatible species next to each other. Species that are more aggressive in establish­ment should be kept away from species that do not estab­lish well with competition. Where compatible species are kept separate, all seeded species can become established and do well (fig. 4).

Seeding equipment that includes a seedbox (such as drills or disk-chains) can be modified to segregate seed of various species. Seed of selected species can be separated from each other with partitions within the seedbox or by being placed in different seedboxes and seeded through separate seed drops. Most shrub and many forb seedlings do not establish or compete well when planted in close proximity to most perennial grasses. This is especially true for the more aggressive grass species such as stan­dard crested, fairway crested, Siberian wheatgrass (Agro­pyron sibiricum), intermediate wheatgrass, smooth brome (Bromus inermis), and Russian wildrye (Psathyrostachys juncea).

Variations in seed mixing procedures ofmultispecies mixtures can provide greater landscape patchiness diver­sity, and appearance. Several variations can result by mixing only a portion of the seed prior to seeding and put­ting the mix and bags of single species into the seed bin (broadcast) or drill box at random. As a result there will be areas where all species are seeded simultaneously, areas with only one or a few species, and all gradations in between. This can result in excellent foraging areas adjacent to various types of habitat. The esthetic effect is a more natural appearance with vertical and horizontal variation rather than an even unnatural appearance.

It is important to seed species that are adapted to site conditions. Early and mid-sera! species generally do best in the disturbed scalps or pits and are generally success­ful in spreading naturally into existing perennial and annual communities. Species that have performed well when interseeded include big sagebrush (Artemisia tridentata), rubber rabbitbrush (Chrysothamnus naus­eosus), fourwing saltbush (Atriplex canescens), forage kochia (Kochia prostrata), antelope bittcrbrush (Purshia tridentata), alfalfa (Medicago sativa), small burnet (San­guisorba minor), Lewis flax (Linum perenne), Palmer

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penstemon (Penstemon palmerii), yellow sweetclover (Melilotus officinalis), western yarrow (Achillea mille­folium ), globemallow (Sphaeralcea spp.), and mountain rye (Secale montanum).

TRANSPLANTING

A number of shrubs (fig. 5) and forbs have been success­fully transplanted into established grass stands to en­hance species composition, stabilize soil, increase the quality and quantity offorage, and improve cover value (McArthur and others 1974; Monsen 1974; Shaw 1981; Stevens 1981; Stevens and others 1981; Tiedemann and others 1976). When transplanting into competitive grass, forb, or shrub communities success can be increased by opening spots or strips with an effective herbicide or by scalping the soil and existing plant material. Scalps per­pendicular to the prevailing storm direction can collect considerable snow. Scalping too deep can remove the most fertile portion of the soil and reduce plant growth (Stevens 1985b). Scalping and transplanting are gener­ally done simultaneously with the scalper attached in front of the transplanter.

There are a number of important procedures that must be followed when transplanting. General rules for wild­ings, bareroot, and container-grown stock are: (1) never allow roots to become dry, (2) keep plants cool and out of direct sunlight, (3) compact soil well around the roots at planting time, and (4) plant during cool periods with ad­equate soil moisture (Ferguson and Monsen 197 4; Penrose and Hansen 1981; Ryker 1976; Stevens 1981).

Proper handling of plant materials will usually make the difference between success and failure. Exposed roots ofbareroot stock can dry out in as little as 5 seconds on windy days, and in 15 seconds or less on overcast days. Roots of container stock will tolerate somewhat longer periods of exposure than will bareroot stock roots. Roots need to be kept damp and cool at all times (fig. 6). Roots may become heated or dry when plants are moved from shipment containers to the transplanter holding bin. However, mishandling most commonly occurs just before

Figure 4-Wyoming big sagebrush drill seeded in con­junction with and separated from crested wheatgrass.

Figure 5-Fourwing saltbush, winterfat, antelope bitterbrush, white rubber rabbitbrush and Wyoming big sagebrush transplanted into an established stand of crested wheatgrass.

placing the transplant in the soil. Transplants must to be moved rapidly from the protected holding area into the soil to minimize root exposure.

Transplant stock is generally stored, wrapped, and shipped in plastic or cardboard boxes. Excessive destruc­tive heat can build up quickly in these containers when they are placed in direct sunlight for short periods of time.

Proper placement of transplants in the soil is critical. Planting holes and openings should be deep enough to allow all roots to be straight and the root collar to be at ground level when buried. Plants will die if they are planted too deeply. Roots should be completely vertical, with no "J" or "S" root placement; otherwise, the plant could be stunted or die. Soil should be finnly compacted around all roots. Air pockets must be eliminated. Air pockets and loose soP will result in poor anchoring, drying of roots, poor uptake of water and nutrients and, ulti­mately, the death of the plant.

Within the Intennountain West, transplanting should be done in the early spring. Advantages of planting at this time include: (1) plants are still donnant; (2) the chance of severe frost heaving has passed; (3) soil mois­ture from winter snow will likely be high; (4) two or three spring stonns are likely to follow; and (5) temperatures are low. In the sagebrush and pinyon-juniper types of central Utah, transplanting usually has to occur before mid-March to meet all these requirements. The latest allowable date will vary with elevation, vegetative type, latitude, stonn patterns, and the arrival of spring.

The size and proportion of root and type can affect es­tablishment success. Proper shoot-root ratio is important. For many species the most successful transplanting has resulted with roots from 15 to 30 em (6 to 12 inches) long and tops at least 33 em (13 inches) long (McKenzie and others 1980; Stevens and others 1981). Pruning top growth is sometimes necessary to maintain balance. Too much top growth can put great demand on roots for moisture during the establishment period.

Transplanting results will vary among species (table 1) (Everett 1980; Ferguson and Monsen 1974; Stevens 1980; Tiedemann and others 1976). For example, wildings of

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most sagebrush and rabbitbrush species transplant with 80 to 90 percent success (Stevens and others 1981). About 30 to 40 percent success can be expected with fourwing saltbush bareroot stock with taproots. Success can be in­creased substantially with this species by using root­pruned transplants with branched root systems.

The intensity and timing of grazing can affect trans­planting success. Most transplants need at least 2 years to become well enough rooted and established to endure much use. Grazing pressure should be considered when determining how large an area to transplant and how many plants will be used. Where grazing pressure exists, it is best to cluster transplants rather than scattering them. Based on experience at big game ranges, trans­plants will be better protected if they are planted as an extension of an existing stand. Mature plants can then absorb a major portion of use.

Successful and rapid transplanting can be accomplished with a tractor-mounted reinforced tree transplanter that requires hand placing of transplants. A hand-fed trans­planter can plant from 10 to 18 bareroot stock plants per minute (Stevens and others 1981). Rate varies with the species being planted, soil type, moisture conditions, and spacing between transplants. Rocky ground should be avoided. The automatic pickup and planting system found on some tree transplanters cannot be used suc­cessfully with most shrub bareroot, wilding, or container stock. Most transplantable shrubs have multiple­branched, fibrous, or fairly long root systems that tangle in the fingers and chains of the automatic planting device.

Transplants of many species are available as container­grown or bareroot stock. Container-grown stock may have several advantages over bareroot stock. Roots of container-grown stock are established in a growth medium and are less likely to dry. Container stock is usually avail­able when needed. Bareroot stock cannot be lifted until the frost is out of the soil and may not be available when site conditions are ideal for transplanting. Bareroot stock has several advantages over container-grown stock. When properly planted, bareroot stock generally has a higher rate of survival (Croft and Parkin 1979), establishes more

Figure 6-Transplants in holding bin on trans­planter. Roots of transplants must be kept damp and cool at all times.

Table 1-Expected transplanting establishment success from various shrub, forb and grass species, bareroot, wilding and container grown stock1

Bareroot and Container-Species Common name wilding stock grown stock

Shrubs:

Amelanchier a/nifolia Saskatoon serviceberry 6 4 Artemisia abrotanum Oldman wormwood 10 Artemisia nova Black sagebrush 10 10 Artemisia tridentata ssp. tridentata Basin big sagebrush 10 10 Artemisia tridentata ssp. vaseyana Mountain big sagebrush 10 10 Artemisia tridentata ssp. wyomingensis Wyoming big sagebrush 8 8 Atriplex canescens Fourwing saltbush 3 1 Ceratoides lanata Wlnterfat 6 2 Cercocarpus ledifolius Curlleaf mountain-mahogany 5 2 Cercocarpus montanus True mountain-mahogany 5 2 Chrysothamnus nauseosus ssp. White rubber rabbitbrush 8 7 albicaulis and ssp. hololeucus

Chrysothamnus viscidiflorus Low mountain rabbitbrush 7 7 Colutea arborescens Bladdersenna 5 4 Cowania stansburiana Cliffrose 5 4 Ephedra viridis Green ephedra 4 1 Kochia prostrata Forage kochia 8 8 Peraphy/lum ramosissimum Squawapple 5 4 Purshia tridentata Antelope bitterbrush 6 4 Quercus gambelii Gambeloak 5 2 Rhus trilobata Skunkbush sumac 5 Rhusglabra Rocky Mountain sumac 5 Ribas aureum Golden currant 8 8 Rosa woodsii Woods rose 8 8 Sambucus caerulea Blueberry elder 5 4 Sarcobatus vermiculatus Black greasewood 3 1 Symphoricarpos spp. Snowberry 9 9

Forbs:

Achillea millefolium Western yarrow 10 10 Artemisia ludoviciana Louisiana sagebrush 10 10 Asterspp. Aster 10 10 Balsamorhiza sagittata Arrowleaf balsamroot 1 Coronil/a varia Crownvetch 10 10 Hedysarum boreale Utah sweetvetch 5 8 Linum perenne Lewis flax 8 8 Lupinus spp. Lupine 2 6 Medicago sativa Alfalfa 6 8 Sanguisorba minor Small burnet 6 7 Sphaeralcea spp. Globemallow 8 8 Viguriera multiflora Showy goldeneye 6 9

Grasses:

Bunch grasses 8 10 Sod grasses 10 10

110 = high percent of establishment can be expected when proper transplanting techniques are used; 1 = low percent of establishment can be expected, even when proper transplanting techniques are followed.

quickly, and is larger and more vigorous (Stevens 1980). Bareroot stock is generally older ( 1 to 3 years) (Stevens 1981) than container stock (3 to 4 months) (Penrose and Hansen 1981). Bareroot stock generally has woody stems and fibrous root systems. Container stock is generally grown under forced conditions, resulting in young, some­times weak, spindly plants with only one small taproot. For most shrub species, bareroot stock is less expensive

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than container stock, considering purchase price and transplant cost for each established plant (Croft 1980).

CONCLUSIONS

To enhance shrub and forb communities in the Inter­mountain West, both interseeding and transplanting have

proven effective methods of increasing diversity. If either is undertaken, I recommend:

1. Temporary elimination of competitive plant material by proper use of scalping or herbicides.

2. Interseeding mixed seed collections to increase chances of success and vary appearance and diversity. However, only compatible species s~ould be seeded next to each other and species need to be adapted to site conditions.

3. When transplanting, never let roots dry out, keep plants cool and shaded, compact soil well around roots. Proper stem/root ratio is important. Plant early in spring when weather is cool and soil is moist.

4. Keep grazing pressure off newly planted or seeded areas for at least 2 years following planting.

5. Since bareroot stock is hardier, older, and more eco­nomical, I recommend use ofbareroot stock for trans­planting unless site conditions are optimum too early in spring when only container-grown stock is available.

ACKNOWLEDGMENTS Research was facilitated by Federal Funds for Wildlife

Restoration, Pittman-Robertson Project W-82-R, Study 5, and the Intermountain Research Station, Forest Service, U.S. Department of Agriculture.

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