Development of Native Plant Materials for Restoration and Rehabilitation of Colorado Plateau Ecosystems

Transcription

1 Development of Native Plant Materials for Restoration and Rehabilitation of Colorado Plateau Ecosystems Author(s): Troy E. Wood, Kyle Doherty and Wayne Padgett Source: Natural Areas Journal, 35(1): Published By: Natural Areas Association DOI: URL: BioOne ( is a nonprofit, online aggregation of core research in the biological, ecological, and environmental sciences. BioOne provides a sustainable online platform for over 170 journals and books published by nonprofit societies, associations, museums, institutions, and presses. Your use of this PDF, the BioOne Web site, and all posted and associated content indicates your acceptance of BioOne s Terms of Use, available at Usage of BioOne content is strictly limited to personal, educational, and non-commercial use. Commercial inquiries or rights and permissions requests should be directed to the individual publisher as copyright holder. BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research.

2 C O N S E R V A T I O N I S S U E S Development of Native Plant Materials for Restoration and Rehabilitation of Colorado Plateau Ecosystems Troy E. Wood 1,4 1 US Geological Survey Southwest Biological Science Center Colorado Plateau Research Station Bldg 56 PO Box 5614 Northern Arizona University Flagstaff, AZ Kyle Doherty 2 Wayne Padgett 3 2 Department of Biological Sciences Northern Arizona University Flagstaff, AZ Bureau of Land Management 440 W. 200 S., Suite 500 Salt Lake City, UT Corresponding author: twood@usgs.gov; Natural Areas Journal 35: ABSTRACT: The native plant communities of the Colorado Plateau have been substantially degraded by human activity, yet in many areas retain a basic natural ecologic integrity. The more heavily impacted regions often require active intervention. Historically, this intervention has been conducted primarily by seeding introduced grasses selected for their forage characteristics. Recent management initiatives that reflect broader goals have highlighted the need to develop native plant materials that can be used to return diverse, resilient communities to degraded areas. The Colorado Plateau Native Plant Program was established to identify the best native plant species, and seed sources within species, that can be used to meet this need. We present an overview of the Program s past and current activities and highlight research and development strategies used to increase the availability of native plant materials adapted to target sites. Index terms: Colorado Plateau, local adaptation, native plant materials development, restoration INTRODUCTION The Colorado Plateau Native Plant Program and Its Scope Like other western landscapes, the public lands of the Colorado Plateau (CP) have been impacted intensely by human activities such as livestock grazing (e.g., Abruzzi 1995) and mining, which have degraded the integrity of most, if not all, native ecosystems (USDA, Office of the Secretary 1936). Simple observation as well as formal quantitative study (e.g., Shinneman et al. 2008) has made it clear that active intervention is required to restore ecosystem function to many impacted areas. In addition, the expanded use of public CP lands, for example for energy development (Bryce et al. 2012), and the predicted magnitude of climate change, which is expected to be especially great on the CP (USGCRP 2009), indicate that the threats to public lands will become more severe. Historically, treatment of degraded lands has been conducted largely with introduced grasses, but the long-term value of their use has come under question (Johnson et al. 2010). The Colorado Plateau Native Plant Program (CPNPP) was founded by the US Bureau of Land Management (BLM) to ensure sustained commitment to the development of genetically appropriate native plant materials for use in both reactive and proactive mitigation of ecosystem degradation of public lands on the CP. The Program is part of a nationwide native plant materials development program established by the BLM s Washington Office (BLM 2009; Tishew et al. 2011). The BLM s efforts to increase the use of native, relative to introduced, plants in seeding treatments reflect its multiple-use mission, with consideration being given to the relative values of the resources range natural scenic, scientific and historical and not necessarily to the combination of uses that will give the greatest economic return (Federal Land Policy and Management Act of 1976, As Amended; US Department of Interior 2001). This mission is, in some settings, in discord with the use of introduced grasses, which were principally selected based on their ability to supply livestock forage, and like other crop plants, mediate resource extraction for economic gain. For example, on the CP, crested wheatgrass has been used extensively after pinyon-juniper removal to enhance livestock grazing (Redmond et al. 2013). In the context of restoring basic ecosystem function to a site, the main argument for the continued use of introduced species is that they are proven to perform better than natives. Those that argue for the increased or exclusive use of natives point out: (1) that we lack the data to conclude that introduced species are more likely to establish and persist, and (2) that currently available lines may fail because they are not sourced from appropriate populations. So far, this debate has been founded more on philosophy than on data, which can be found to support both sides. For example, native seed mixes can perform better than exotic mixes in some settings (Thompson et al. 2006). In contrast, other studies have shown that exotics can have higher establishment and persistence than natives in field (Robertson et al. 1966) and experimental (Robins et al. 2013) conditions. While data alone will not resolve the debate in all minds (Conner 2008), clearly, an objective synthesis of relevant studies is needed. 134 Natural Areas Journal Volume 35 (1), 2015

3 BLM s focus on natives also reflects a more recent directive to provide for restoration of native species and habitat conditions in ecosystems occupied by invasive species (Executive Order 13112, 1999; for other relevant policy see Johnson et al. 2010). In this context, the value of introduced species is substantial: it is well known that certain introduced species used in range improvement can outcompete invasives, particularly at intensively transformed sites such as abandoned agricultural fields (e.g., Stewart and Hull 1949). However, these same species can also displace natives via greater propagule production (Marlette and Anderson 1986; Pyke 1990) and direct competition, and often become monocultures. This problem highlights the CPNPP s chief goal: to provide genetically appropriate native plant materials that can be used to restore ecosystem function to degraded sites and that can persist, as diverse native plant communities, in the face of historical and novel stressors (CPNPP 2011). Achievement of this ambitious goal will require sustained, creative, and collaborative effort, as exemplified by the earlier-established Great Basin Native Plant Project (Shaw et al. 2012). Since its inception, the CPNPP has actively engaged with land managers, federal agency and university researchers, nongovernmental organizations (NGOs), Plant Materials Centers, and commercial growers to move toward this goal. In this paper, we present an overview of past and current activities of these partners, discuss future paths, and highlight emerging challenges. How has the CPNPP defined the Colorado Plateau, that is, the spatial scale of its efforts? After all, the CP has been defensibly delimited in diverse ways. While sometimes substantially different, the various delineations of the CP are based on many of the same landscape features: (1) the sharp floristic transition between the CP and the Great Basin to the northwest, (2) the Colorado Rocky Mountains to the east, (3) the Uinta Mountains to the north, and (4) the Mogollon Rim to the south. The CP boundary that we use is more extensive than most other forms, particularly in its southward reach and inclusion of inter-montane regions of northern New Mexico and southern Colorado (Figure 1). As defined here, the region circumscribes just under 400,000 km 2, and a substantial fraction of this area is publicly owned. Because the primary funding for the CPNPP comes from the BLM, the Program s focus is on the development of native plant materials adapted to CP lands managed by this agency. These lands are generally of lower elevation, with the US Forest Service managing the higher elevation public lands on the CP. In general the US National Park Service develops their own plant materials, which are derived from within their parks. The CP is characterized by extraordinary geologic, topographic, and climatic complexity and harbors strikingly high vascular plant species diversity, including a high incidence of endemism (Krause et al. in press). In contrast, abundant CP plant species targeted for restoration occupy broad niches (Appendix), and some have been shown to comprise multiple ecotypes that differ subtly in visible characters that have not been recognized by taxonomists. A fundamental challenge of the CPNPP is to capture the ecotypic diversity within these abundant species when developing commercially available seed lines, which will facilitate the establishment of diverse communities (Booth and Grime 2003) and prevent ecologic homogenization, a problem that has emerged in global regions with higher human population density (e.g., Winter et al. 2009). In other words, the CPNPP does not simply want to facilitate restoration that returns natives to the landscape, but rather the right natives, those that are adapted to site conditions and adaptable to future change, and that can coexist in diverse communities. PROGRAM FOCUS AREAS Partnerships and Outreach Because the CPNPP works at an ecoregional scale and on diverse problems that span many disciplines, a critical step has been to establish a coordinated network of partners. Since its inception, the CPNPP has developed partnerships with key BLM entities, other federal agencies, state agencies, nonprofit conservation organizations, university researchers, volunteers, and others. A list of key CPNPP partners, and a brief summary of their focal contributions, is presented in Table 1. A sample of these contributions is described in detail in the following sections. The CPNPP is also dedicated to outreach efforts, which have focused on training the next generation of plant conservationists, increasing awareness of the importance of the use of native plants in restoration, and expanding the scope of research efforts. For example, the Program has contributed to the training of master s degree program students, provided undergraduates opportunities to conduct research on native plant restoration, and is working with atrisk high school students to address basic restoration research questions. In addition, the Program has funded the establishment of a native plant demonstration garden at the University of Utah s Rio Mesa Center, and has been directly involved with the development of the Southwest Chapter of the Society for Ecological Restoration. Identification of Priority Species A basic, and challenging, initial step was the assembly of a short list of priority native plant species with high potential for successful use in large scale restoration. Before the CPNPP was established, the Uncompaghre Partnership (UP; see Table 1) had completed substantial work on native plant materials development for important CP species. Accessions of some of these species are under increase by commercial growers (Table 2). This work, coupled with input from national and regional botanists, led to a working list of 100 species. This working list was winnowed to a target list by a committee that considered multiple factors, including potential for agronomic increase, a market survey of land managers (Peppin et al. 2010), watershed protection, provision of pollinator and/or vertebrate habitat, and complementarity of species contributions to ecosystem services (Appendix). Partners have ranked the species on this target list via questionnaire, and this ranking guides CPNPP research and development efforts. An important next step is to perform an explicitly quantitative needs assessment of native species. Volume 35 (1), 2015 Natural Areas Journal 135

4 Figure 1. The Colorado Plateau boundary as defined by the Colorado Plateau Native Plant Program. Omerik Level III Ecoregions are displayed; for simplicity, small portions of the Wasatch & Uinta Mountains and Southern Rockies ecoregions included here are dissolved into the Colorado Plateaus ecoregion. Multiple resources provide a starting point for such an assessment, for example: (1) the CP Rapid Ecoregional Assessment (Bryce et al. 2012), (2) Landfire data layers, and (3) the US Geological Survey s Land Treatments Digital Library (CP data are currently being entered). Such resources can be used to identify regions that have the highest likelihood of future restoration need. This type of spatial analysis can be coupled with available information on the distributions of priority restoration species to identify those species most likely to be needed for future restoration and rehabilitation efforts. Finally, assessment of past treatments, while costly to execute, can be used to infer which species have the highest likelihood of establishment and persistence within specific regions and which ecological sites can be effectively treated (e.g., Arkle et al. 2014). 136 Natural Areas Journal Volume 35 (1), 2015

5 Table 1. Key partners and their contributions to the Colorado Plateau Native Plant Program. While perhaps obvious, it is important to point out that restoration goals and the target site must guide the selection of species for development. For example, Meinke et al. (2009) evaluated sagebrush habitats for restoration potential, and their study was motivated by the goal of ensuring sufficient habitat for the Greater Sage-Grouse (Centrocercus urophasianus Bonaparte). The Greater Sage-Grouse is a game bird whose numbers have significantly declined over recent decades and that is currently under consideration for federal listing by the US Fish and Wildlife Service. Clearly, in this case, native species that co-occur with sagebrush and that correlate with grouse occupancy will be prioritized over those that do not. Similarly, riparian areas are a major priority for restoration in the Southwest, where they have been drastically altered by salt cedar (Tamarix spp.) infestation (Beauchamp and Shafroth 2011). This need has taken on a high priority with the success of the tamarisk beetle (Diorhabda carinulata Desbrochers), which has begun to cause salt cedar dieback. Restoration of these degraded areas that are in a major ecological transition requires the use of woody and herbaceous species that are adapted to the unique hydrology and edaphic conditions of the riparian zone. In addition, it has been reported that many native species from semi-arid landscapes have not been exposed to selection by naturally occurring grazers (Mack and Thompson 1982), and it is likely that natural (nondomesticate) grazing pressure has been variable across a species range and at the scale of the CP. Thus, if a key restoration goal is to establish a native community that is resilient to grazing, then sourcing from grazing adapted species, or lines within species, is critical. More focused approaches can be used; for example, Shinneman et al. (2008) used comparisons between undisturbed (reference) and degraded sites to characterize differences in composition and abundance within similar vegetation communities on the Uncompaghre Plateau in western Colorado. This approach is useful if the goal is to restore to reference condition. In summary, restoration goals can be diverse and vary with respect to spatial extent, and different goals lead to very different species priority rankings. Because species prioritization is ultimately goal- and sitedependent, a flexible approach that can be deployed across different goals and sites and that can weight multiple, competing goals in determining priorities is needed. A sketch of such an approach is outlined at the end of the next section. Evaluation of Priority Species Overview Myriad reciprocal transplant studies show that plants are locally adapted (reviewed in Leimu and Fischer 2008) and that the strength of local adaptation is strong on average, with a 45% relative fitness advantage to the local source as assessed by Hereford (2009). In rare cases, the physiological mechanism underlying local adaptation has been elucidated; for example, Comstock and Ehleringer (1992) linked climate conditions at source site to water-use strategies in a common garden study of burrobrush (Hymenoclea salsola Volume 35 (1), 2015 Natural Areas Journal 137

6 Table 2. Climate data (mean and st. dev. or single point) of a sample of CPNPP priority species based on CP (Colorado Plateau) occurrences. Also included are named germplasm accessions and Seeds of Success (SOS) collections from the four corners states (AZ, CO, NM, UT; the numbers of collections reported may not be current). Climate data were derived from org, where details on each variate can be found. Traits differing in common garden studies available to the authors are also summarized. 138 Natural Areas Journal Volume 35 (1), 2015

7 Table 2. (Continued) Volume 35 (1), 2015 Natural Areas Journal 139

8 Table 2. (Continued) 140 Natural Areas Journal Volume 35 (1), 2015

9 Table 2. (Continued) Volume 35 (1), 2015 Natural Areas Journal 141

10 Table 2. (Continued) 142 Natural Areas Journal Volume 35 (1), 2015

11 Table 2. (Continued) Volume 35 (1), 2015 Natural Areas Journal 143

12 Torr. & A. Gray), where plants from sites that differed in water stress exhibited genetic differences in water-use physiology. More specifically, several studies demonstrate that, in restoration settings, local genotypes have superior performance, relative to nonlocal materials, although a local advantage may not emerge across the first few growing seasons (Humphrey and Schupp 2002; Petersen et al. 2004; Zeiter and Stampfli 2009; Noel et al. 2011; Hufford et al. 2012). The commonality of local adaptation in plants has led to a focus in native plant restoration on defining seed transfer zones, zones within which plant propagules can be moved with minimal risk of establishment and persistence failure (Hufford and Mazer 2003). It is important to note, however, that in a substantial fraction of studies of local adaptation, one of the sources had higher or equivalent fitness at both sites (Leimu and Fischer 2008). This observation suggests that a single source for a given species may have broad applicability, but a major caveat is that the environmental space and number of generations evaluated in the reviewed studies is very small relative to the scale at which traditional cultivars are deployed. Consequently, information on the scale of ecotypic differentiation within restoration species should continue to guide the development and sourcing of native plant materials to ensure that materials are used at sites to which they are adapted. In the absence of experimental data on individual plant species, general seed transfer guidelines can be obtained by mapping spatial variance in climatic variables inferred to be particularly important to shaping plant adaptive tradeoffs (and thus ecotypic or clinal differentiation). This conceptual approach has been used to develop an accessible, web-served tool (Bower et al. 2014). While this generalized method is necessarily naïve to the biology of individual plant species, seed transfer zones (zones of climatic similarity based on temperature and aridity) derived from it sometimes explained greater variance in important plant fitness traits than zones derived from common garden studies. However, these statistical comparisons were performed for only three species: one forb, tapertip onion (Allium acuminatum Hook.), and two grasses, Indian ricegrass (Achnatherum hymenoides (Roem. & Schult.) Barkworth) and bluebunch wheatgrass (Pseudoroegneria spicata (Pursh) Á. Löve). Both of the grass species fix carbon via C3 (cool season) photosynthesis. Zones based on annual means of aridity may not perform as well for C4 (warm season) taxa, for example, where the timing of precipitation may be a more important driver of adaptive strategies than annual precipitation (Teeri and Stowe 1976). Nonetheless, climate data based seed transfer guidelines can clearly be derived from spatial patterns in other variates that are inferred to better reflect the biology of focal species. In addition to increasing immediate and long-term restoration success via source to site matching (Hufford and Mazer 2003) and retention of adaptive potential (Srgo et al. 2011), there are other important reasons to preserve the natural magnitude and pattern of genetic variation within restoration species and to use multiple, genetically diverse sources for these species. First, it is well known that loss of species diversity negatively impacts ecosystem productivity (Hooper et al. 2012), and species diversity of artificially established populations is positively correlated with the levels of intraspecific genetic diversity within the founding populations (Booth and Grime 2003). Taken together, these studies indicate that the preservation of genetic diversity within restoration species can facilitate the local maintenance of plant species diversity, which in turn may facilitate the maintenance of biotic diversity up the trophic chain (Keith et al. 2010). Furthermore, artificial selection for agronomic traits such as yield can quickly erase complex adaptations shaped by natural selection; for example, selection for increased growth rates in switchgrass (Panicum virgatum L.) led to increased susceptibility to viral infection (Schrotenboer et al. 2011). Similarly, in sunflower (Helianthus annuus L.), adaptation of weedy lines to cultivated settings that allows them to invade domesticate stands also increases their susceptibility to drought stress (Mayrose et al. 2011). These examples highlight the well-documented observation that selection or traits favorable in cultivated settings can cause genetic changes with strongly negative pleiotropic effects on fitness in more natural settings (Coyne and Lande 1985). The Program s goal of establishing diverse native plant populations reflects the above observations and contrasts with the traditional model of the broad use of native and nonnative cultivars, which sometimes emphasizes selection for agronomic traits at the expense of ecologic fitness (Kulpa and Leger 2013), and which can lead to homogenization within cultivated lines and, subsequently, the communities they are used to establish (Pellant and Lynse 2005). Nevertheless, the historic model is more in line with current market realities this approach has proved to be effective at identifying single and composite sources of plant species that yield sufficient, readily harvested quantities of seed under cultivation. In general, these species can establish in diverse climatic settings, at least under relatively controlled soil conditions (i.e., tilling and weed treatment; Robins et al. 2013). In recognition of this fact, a fundamental goal of the CPNPP is to find a middle ground between the traditional approach and one that recognizes the importance of retaining naturally selected diversity throughout the development of native plant materials. Clearly, effective, practical increase strategies are needed that yield sufficient quantities of genetically diverse native plant materials that can establish and persist in restoration settings. Fortunately, a basis for their further development is already available (e.g., Munda and Smith 1995; Tooker and Frank 2012). Common Garden Studies of Colorado Plateau Priority Species Common garden studies, where individuals of multiple populations of a single species are grown under uniform conditions, allow one to differentiate between heritable and plastic causes of divergence among populations (Turesson 1922). In many cases, trait differences among populations in a common garden can be related to differences in the natural habitat from which the common garden plants were sampled 144 Natural Areas Journal Volume 35 (1), 2015

13 (Turesson 1922). Thus, linking trait variation expressed within a common garden to source site characteristics can lead to inference of adaptive trait differences among populations of a species, and these differences can inform transfer guidelines (e.g., Johnson et al. 2012). Two common garden studies of CP priority species, led by CPNPP partners, are ongoing. In a collaborative effort between the UP and the US Forest Service, multiple (>20) accessions of five C3 grasses prairie Junegrass (Koeleria macrantha (Ledeb.) Schult.), muttongrass (Poa fendleriana (Steud.) Vasey), Sandberg bluegrass (Poa secunda J. Presl), squirreltail (Elymus elymoides (Raf.) Swezey), and needleand-thread (Hesperostipa comata (Trin. & Rupr.) Barkworth ) were grown at five common garden sites (Memmott et al., unpubl. data). The garden sites ranged from 1600 to 2377 m in elevation. Survival, height, crown diameter, number of inflorescences, and above ground biomass were estimated for each accession of each species at the end of the fourth growing season. Per cent survival was highly variable across species, accessions, and grow-out sites, with means of maximum site survivorship across the species ranging from 42.0 to 93.7%. No single accession had highest survivorship at more than two grow-out sites. In addition, for all species, grow-out site was a significant predictor of survival and crown diameter. In the second common garden study, led by the US Geological Survey, 44 accessions of blue grama grass (Bouteloua gracilis (Kunth) Lag. ex Griffiths), drawn from across the CP and adjacent regions, are being evaluated for ecophysiological and other fitness traits near Flagstaff, Arizona (climate at the site, Arboretum garden, provided in Table 2). Blue grama grass is in demand by land managers for use in restoration, particularly across the southern portion of the CP (Peppin et al. 2010). Analyses of potential climate predictors of performance measures are ongoing for both of these studies. While the implications of these two studies for materials development have not yet been fully evaluated, the published literature contains numerous reports on CPNPP priority species. These studies, a sample of which is summarized in Table 2, vary with respect to their utility in inferring seed transfer guidelines yet all contain valuable information. Furthermore, Table 2 is not exhaustive, and a more comprehensive survey is needed. For example, more data lay behind official releases from Natural Resources Conservation Service s Plant Materials Centers, but these evaluation data can be difficult and time consuming to interpret. Nonetheless, it would be wise to evaluate the extent and quality of these and similar data and the cost of their analysis in light of the full costs of new common garden studies. Even if formal, empirical seed transfer zones cannot be derived from such a synthesis, a basic, achievable aim could be to infer simple rules. For example, Barnes (2009) determined that winterfat (Krascheninnikovia lanata (Pursh) A. Meeuse & A. Smit ) seeds should be derived locally or drawn from colder, higher elevation sources relative to a target site; and, similarly, another study indicates that moving blue grama sources down a temperature gradient (to colder sites) can dramatically decrease survivorship (Rogler 1943). This latter observation has been recorded for many C4 restoration grass species and may indicate a generality (Jacobsen et al. 1986). Unfortunately, readily available blue grama sources are derived from populations that are adapted to climates that are significantly warmer than many of the CP sites at which they would be deployed. Of course, an important, outstanding question is whether or not seeds derived from warmer (drier) sites would have an establishment advantage that outweighs the survivorship costs induced by temperature stress in these species. Finally, the common garden data presented in Table 2 are derived from studies conducted at various scales, with some sampled across regions much larger than the CP. Consequently the ecological distances (e.g., sensu Hereford 2010) among source sites are substantial. Do we see substantial fitness (performance) differences in these studies at the scale of ecological contrasts between cultivar sources and conditions at sites where they have been used on the CP? Species Distribution Modeling and Plant Materials Development Many studies make it clear that adaptive differentiation within plant species is, in part, driven by climatic factors (e.g., Anderson et al. 2012), a fact that is corroborated by the predictive power of climate-based transfer zone delineation described above (Bower et al. 2014). Furthermore, the magnitude of adaptive differentiation among plant populations can be predicted by the amount of environmental differences among population sites (Hereford 2009; Noel et al. 2011; Sexton et al. 2014). Based on this general pattern, CPNPP researchers have used occurrence records and species distribution modeling (SDM) tools (Thuiller et al. 2009) to characterize habitat occupancy of CPNPP priority restoration species. A subsequent step is to evaluate the extent to which intraspecific habitat diversity, which can be evaluated quantitatively with SDM (e.g., Sork et al. 2010), is captured by existing plant materials, including cultivars and undeveloped germplasm accessions (Table 2). More importantly, the intersection of modeled habitat occupancy with disturbance layers that are inferred to be predictive of restoration or reclamation need (Bryce et al. 2012) will allow the CPNPP to identify, objectively, which species, and which sources of those species, should be developed first. Source identification could be based on investigation of the risk (fitness loss) of using potential sources of target species at target sites. The source (or sources, depending on what is deemed practical) that would minimize ecological mismatch across an identified set of target sites (e.g., regions predicted to be impacted by energy development in the near future) should be developed first, or, if already developed, that information communicated to growers. Finally, a further refinement of this approach that would allow tighter focus of efforts and limited resources would be to index sites predicted to require restoration or reclamation by their potential to be positively impacted by intervention (e.g., Meinke et al. 2009). This spatial intersection approach, which is based on readily available data, provides a flexible model for prioritizing native plant material development efforts. This flexibility is critical given the dynamic nature of management foci, and thus funding availability (e.g., the rapid shift towards funding projects related to Greater Sage-Grouse management), and emergence of new stressors. Volume 35 (1), 2015 Natural Areas Journal 145

14 Biocrust Mosses While native plant restorationists have generally focused on the development and use of vascular flora, on the CP biocrusts perform unique, critical ecological functions ranging from soil stabilization (Mazor et al. 1996) to inhibition of cheatgrass (Bromus tectorum L.) invasion (Reisner et al. 2013). Their effects on soil stabilization can have far-reaching effects by diminishing windborne dust flux, which can alter snow-pack driven hydrology of the Colorado River Basin (Painter et al. 2010). Because of the unique ecological contributions of biocrusts and their sensitivity to disturbance, biocrust status at a site is often used as a metric of that site s ecological integrity (Pellant et al. 2000). Indeed, the preservation of biocrusts is a focal element of the ongoing revision to the grazing management plan of the BLM-managed Grand Staircase-Escalante National Monument. While the potential use of biocrusts has been mostly overlooked, recent work suggests that biocrusts can be actively restored in certain settings (Bowker 2007; Xu et al. 2008). On the CP, many biocrusts are occupied, and sometimes dominated by, moss species. Two of the most important biocrust mosses are Syntrichia caninervis Mitten and S. ruralis (Hedw.) Web. & Mohr. The CPNPP has funded work to explore the population biology and restoration potential of these two Syntrichia species. Ongoing work includes: (1) the development of protocols for rapid biomass increase, including an investigation of the effects of timing of hydration on increase of S. ruralis; (2) among population differences in greenhouse growth rates (both moss species and soil microbial associates); and (3) the development of a large panel of genetic markers for S. ruralis that will provide insight into this species standing level of genetic diversity and frequency of sexual reproduction, both of which influence its adaptive potential. Polyploidy and Native Plant Restoration Variation in ploidy level is an important component of intraspecific plant diversity (Keeler 1998; Wood et al. 2009), but it is often overlooked in applied restoration (e.g., Breed et al. 2013). Program researchers are studying the incidence and spatial structure of ploidy variation within native plant species that are used regularly in restoration. Because ploidy variation is known to impact ecology, fertility, and crossability, information on ploidy level should be incorporated into native plant material development and seed sourcing decisions. For example, the genetic isolation that separates cytotypes within species can constrain response to rapid climate change and other selection pressures by limiting the spread of advantageous alleles via both pollen and seed movement. Essentially, the spatial structure of ploidy variation may act as a cryptic form of habitat fragmentation, which limits adaptive response to climate change (Jump et al. 2005). Consequently, effective strategies that mitigate the potentially negative impacts of the movement of cytotypes should be developed and deployed. Manipulating Germplasm to Hedge Bets and Increase Adaptation The spatial approach to prioritizing development efforts as outlined above ignores an obvious and fundamental challenge: climatic regimes at sites predicted to be in need of restoration are expected to change. On the CP, these changes are expected to be especially large, thus even regions not predicted to be impacted by direct disturbance (energy development, wildland fire) are susceptible to further loss of ecologic integrity. Multiple studies have suggested that plant species, even those with short generation times (Wilczek et al. 2014), will often not be able to respond fast enough to keep pace with climate change (Loarie et al. 2009). While one could partly address this challenge within the spatial modeling framework above, we discuss a different approach based on controlled breeding. Plant evolutionists have long recognized that hybridization among lineages can facilitate adaptation by expanding heritable variance for fitness related traits (Anderson and Stebbins 1954). The following observation, from classic work on local plant adaptation work that has had a strong influence on efforts to use local genotypes in native plant restoration points to a very different approach than matching local genotypes to their zone of adaptation: Perhaps the most interesting class of all is represented by the plant -65 Such plants exhibit exceptional vigor at all three stations, combining the survival capacities of both climatic races. Plants of this class suggest that new ecotypes may arise through the crossing of existing ecotypes followed by natural selection of the progeny. Presumably some of these should be able to establish themselves in new environments possibly in habitats which may arise in the future (Hiesey et al. 1942; emphasis added). Plant geneticists have developed tools to identify the genetic determinants of such increased vigor in segregating hybrid populations, and a simple genetic model can explain transgressive segregation for vigor and for specific fitness traits (de Vicente and Tanksley 1993; Rieseberg et al. 1999; Rieseberg et al. 2003). Numerous studies indicate that most transgressive traits in hybrids result from the additive, complementary effects of alleles residing at distinct loci in the parental populations. For example, crossing two populations that are separated geographically but that occupy similar habitats may result in hybrids that are homozygous for the globally more adaptive allele at each of two or more loci. This type of hybrid vigor is heritable, unlike heterosis (heterozygosity at individual loci). A recent study suggests that controlled crossing (here between disjunct populations occupying the warm edge of the species range) can increase fitness (Sexton et al. 2014). Selective breeding directed simply at increasing variance in traits that can be linked to ecological adaptation or specifically at creating lines adapted to individual stressors (e.g., drought, herbivory, invasive competitors (Ferrero-Serrano et al. 2009) may hold great potential for the development of native plant germplasm. As a history of unfounded hubris makes clear, this potential needs to be weighed against potential risks of mediating evolutionary processes (Jones and Monaco 2009)). CONCLUSION AND FUTURE DIRECTIONS While current seed use quantities on the CP are small relative to some other ecoregions, past and predicted stressors point to a need 146 Natural Areas Journal Volume 35 (1), 2015

15 for expanded development of native plant materials for this region. Active research and synthesis of relevant existing data are being used to determine which species, and sources within species, should be moved toward agronomic increase. As research on the ecological diversity and adaptability of CPNPP priority species matures, we must shift our focus to rigorous, on the ground evaluation of predictions based on this research. Importantly, these evaluations need to be conducted with agronomic and seed market realities in mind. Finally, the CPNPP is developing a basic set of tools that will allow it to respond to shifts in predicted needs and to efficiently characterize diversity within native species that are most likely to meet them. ACKNOWLEDGMENTS We thank John Bradford, Andrea Kramer, Adrienne Pilmanis, and Nancy Shaw for providing comments and suggestions that greatly improved the manuscript. Megan Haidet provided Seeds of Success data and assisted with the production of Figure 1. Rachel Ostlund assisted with the literature review for Table 2. Kelly Memmott shared data from his common garden evaluations of C3 grasses. Any use of trade, product or firm names is for descriptive purposes only and does not imply endorsement by the US Government. Troy Wood serves as the Science Lead for the CPNPP. His research is focused on the genetic basis of plant adaptation. He received his PhD from Indiana University and completed post-doctoral training at the University of Münster, Germany. Kyle Doherty is a Master s student in the Department of Biology, Northern Arizona University, and is studying the ecology, genetics, and restoration potential of two species in the biocrust moss genus Syntrichia. Wayne Padgett, founding Coordinator, CPNPP, worked as an ecologist for the US Forest Service and the Bureau of Land Management for 30 years and retired from the Bureau of Land Management in the fall of LITERATURE CITED Abruzzi, W.S The social and ecological consequences of early cattle ranching in the Little Colorado River Basin. Human Ecology 21: Anderson, E., and G.L. Stebbins Jr Hybridization as an evolutionary stimulus. Evolution 8: Anderson, J.T., A.M. Panetta, and T. Mitchell- Olds Evolutionary and ecological responses to anthropogenic climate change. Plant Physiology 160: Arkle, R.S., D.S. Pilliod, S.E. Hanser, M.L. Brooks, J.C. Chambers, J.B. Grace, K.C. Knutson, D.A. Pyke, J.L. Welty, and T.A. Wirth Quantifying restoration effectiveness using multi-scale habitat models: implications for sage-grouse in the Great Basin. Ecosphere 5:1-32. Barnes, M.G The Effect of Plant Source Location on Restoration Success: a Reciprocal Transplant Experiment with Winterfat (Krascheninnikovia lanata). PhD Dissertation. University of New Mexico, Albuquerque. Beauchamp, V.B., and P.B. Shafroth Floristic composition, beta diversity, and nestedness of reference sites for restoration of xeroriparian areas. Ecological Applications 21: [BLM] Bureau of Land Management Native plant materials development program: progress report for FY BLM/WO/GI , US Department of the Interior, Bureau of Land Management. Accessed 14 September 2013 < wo/planning_and_renewable_resources/ fish wildlife_and/rare_plants_2.par File.dat/NativePlantProgressReport pdf >. Booth, R.E., and J.P. Grime Effects of genetic impoverishment on plant community diversity. Journal of Ecology 91: Bower, A.D., J.B. St. Clair, and V. Erickson Generalized provisional seed zones for native plants. Ecological Applications 24: Bowker, M.A Biological soil crust rehabilitation in theory and practice: an underexploited opportunity. Restoration Ecology 15: Breed, M.F., M.G. Stead, K.M. Ottewell, M.G. Gardner, and A.J. Lowe Which provenance and where? Seed sourcing strategies for revegetation in a changing environment. Conservation Genetics 14:1-10. Bryce, S.A., J.R. Strittholt, B.C. Ward, and D.M. Bachelet Colorado Plateau Rapid Ecoregional Assessment Report. Prepared for the US Department of the Interior, Bureau of Land Management, Denver, CO. Comstock, J.P., and J.R. Ehleringer Correlating genetic variation in carbon isotopic composition with complex climatic gradients. Proceedings of the National Academy of Sciences 89: Conner, L.F Growing wild: crested wheatgrass and the landscape of belonging. Master s thesis. Utah State University, Logan. Coyne, J.A., and R. Lande The genetic basis of species differences in plants. The American Naturalist 126: [CPNPP] Colorado Plateau Native Plant Program Colorado Plateau Native Plant Program Five-Year Strategy and Action Plan. Bureau of Land Management. Accessed 18 December 2014 < blm.gov/style/medialib/blm/ut/natural_resources/colorado_plateau/remodel_files. Par File.dat/5yearMarch2011. pdf>. de Vicente, M.C., and S.D. Tanksley QTL analysis of transgressive segregation in an interspecific tomato cross. Genetics 134: Executive Order of February 3, Invasive Species. Federal Register 64(25): Ferrero-Serrano A., A.L. Hild, and B.A. Mealor Can invasive species enhance competitive ability and restoration potential in native grass populations? Restoration Ecology 19: Hereford, J A quantitative survey of local adaptation and fitness trade-offs. The American Naturalist 173: Hereford, J Does selfing or outcrossing promote local adaptation? American Journal of Botany 97: Hiesey, W.M., J. Clausen, and D.D. Keck Relations between climate and intraspecific variation in plants. The American Naturalist 76:5-22. Hooper, D.U., E.C. Adair, B.J. Cardinale, J.E. Byrnes, B.A. Hungate, K.L. Matulich, A. Gonzalez, J.E. Duffy, L. Gamfeldt, and M.I. O Connor A global synthesis reveals biodiversity loss as a major driver of ecosystem change. Nature 486: Hufford, K.M., and S.J. Mazer Plant ecotypes: genetic differentiation in the age of ecological restoration. Trends in Ecology & Evolution 18: Hufford, M.B., X. Xu, J. Van Heerwaarden, T. Pyhäjärvi, J.M. Chia, R.A. Cartwright, R.J. Elshire, J.C. Glaubitz, K.E. Guill, S.M. Kaeppler, J. Lai, L.M. Shannon, C. Song, N.M. Springer, R.A. Swanson-Wagner, P. Tiffin, J. Wang, G. Zhang, J. Doebley, M.D. Mc-Mullen, D. Ware, E.S. Buckler, Volume 35 (1), 2015 Natural Areas Journal 147

16 S. Yang, and J. Ross-Ibarra Comparative population genomics of maize domestication and improvement. Nature Genetics 44: Humphrey, L.D., and E.W. Schupp Seedling survival from locally and commercially obtained seeds on two semiarid sites. Restoration Ecology 10: Jacobson, E.T., D.A. Tober, R.J. Haas, and D.C. Darris The performance of selected cultivars of warm season grasses in the northern prairie and plains states. In Proceedings of the Ninth North American Prairie Conference, July 29-August 1, Tri-College University Center for Environmental Studies, Fargo, ND. Johnson, R., L. Stritch, P. Olwell, S. Lambert, M.E. Horning, and R. Cronn What are the best seed sources for ecosystem restoration on BLM and USFS lands? Native Plant Journal 11: Johnson, R.C., M. Cashman, and K. Vance- Borland Project Title: Conservation, Adaptation and Seed Zones for Key Great Basin Species. Great Basin Native Plant selection and Increase Project 8. < greatbasin.shtml>. Jones, T.A., and T.A. Monaco A role for assisted evolution in designing native plant materials for domesticated landscapes. Frontiers in Ecology and the Environment 7: Jump, A.S., and J. Penuelas Running to stand still: adaptation and the response of plants to rapid climate change. Ecology Letters 8: Keeler, K.H Population biology of intraspecific polyploidy in grasses. Pp in G.P. Cheplick, ed., Population Biology of Grasses. Cambridge University Press, Cambridge, UK. Keith, A.R., J.K. Bailey, and T.G. Whitham A genetic basis to community repeatability and stability. Ecology 91: Krause, C.M., N.S. Cobb, and D.D. Pennington. In press. Range shifts under future scenarios of climate change: dispersal ability matters for Colorado Plateau endemic plants. Natural Areas Journal. Kulpa, S.M., and E.A. Leger Strong natural selection during plant restoration favors an unexpected suite of plant traits. Evolutionary Applications 6: Leimu, R., and M. Fischer A metaanalysis of local adaptation in plants. PLoS One 3 e4010. Loarie, S.R., P.B. Duffy, H. Hamilton, G.P. Asner, C.B. Field, and D.D. Ackerly The velocity of climate change. Nature 462: Mack, R.N., and J.N. Thompson Evolution in steppe with few large, hooved mammals. American Naturalist 119: Marlette, G.M., and J.E. Anderson Seed banks and propagule dispersal in crestedwheatgrass stands. Journal of Applied Ecology 23: Mayrose, M., N.C. Kane, I. Mayrose, K.M. Dlugosch, and L.H. Rieseberg Increased growth in sunflower correlates with reduced defenses and altered gene expression in response to biotic and abiotic stress. Molecular Ecology 20: Mazor, G., G.J. Kidron, A. Vonshak, and A. Abeliovich The role of cyanobacterial exopolysaccharides in structuring desert microbial crusts. FEMS Microbiology Ecology 21: Meinke, C.W., S.T. Knick, and D.A. Pyke A spatial model to prioritize sagebrush landscapes in the Intermountain West (USA) for restoration. Restoration Ecology 17: Munda, B.D., and S.E. Smith Genetic variation and revegetation strategies for desert rangeland ecosystems. Pp in B.A. Roundy, E.D. McArthur, J.S. Haley, and D.K. Mann, comps., Proceedings, Wildland Shrub and Arid Land Restoration Symposium, October 1993, Las Vegas, NV. General Technical Report INT-GTR-315, US Department of Agriculture, Forest Service, Intermountain Research Station, Ogden, UT. Noël D., D. Prati, M. van Kleunen, A. Gygax, D. Moser, and M. Fischer Establishment success of 25 rare wetland species introduced into restored habitats is best predicted by ecological distance to source habitats. Biological Conservation 144: Painter, T.H., J.S. Deems, J. Belnap, A.F. Hamlet, C.C. Landry, and B. Udall Response of Colorado River runoff to dust radiative forcing in snow. Proceedings of the National Academy of Sciences 107: Pellant, M., and C.R. Lysne Strategies to Enhance Plant Structure and Diversity in Crested Wheatgrass Seedings. Pp in N.L. Shaw, M. Pellant, S.B. Monsen, comps., Sage-grouse Habitat Restoration Symposium Proceedings; 4-7 June 2001, Boise, ID. Proceedings RMRS-P-38, US Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fort Collins, CO. Pellant, M., P. Shaver, D.A. Pyke, and J.E. Herrick Interpreting indicators of rangeland health. BLM Technical Reference , USDI Bureau of Land Management, Washington, DC. Peppin, D.L., P.Z. Fulé, J.C. Lynn, A.L. Mottek-Lucas, and C. Hull Sieg Market perceptions and opportunities for native plant production on the southern Colorado Plateau. Restoration Ecology 18: Petersen, S.L., B.A. Roundy, and R.M. Bryant Revegetation methods for high-elevation roadsides at Bryce Canyon National Park, Utah. Restoration Ecology 12: Pyke, D.A Comparative demography of co-occurring introduced and native tussock grasses: persistence and potential expansion. Oecologia 82: Redmond, M.D., N.S. Cobb, M.E. Miller, and N.N. Barger Long-term effects of chaining treatments on vegetation structure in pinon-juniper woodlands of the Colorado Plateau. Forest Ecology and Management 305: Reisner, M.D., J.B. Grace, D.A. Pyke, and P.S. Doescher Conditions favouring Bromus tectorum dominance of endangered sagebrush steppe ecosystems. Journal of Applied Ecology 50: Rieseberg, L.H., M.A. Archer, and R.K. Wayne Transgressive segregation, adaptation and speciation. Heredity 83: Rieseberg, L.H., O. Raymond, D.M. Rosenthal, Z. Lai, K. Livingstone, T. Nakazato, J.L. Durphy, A.E. Schwarzback, L.A. Donovan, and C. Lexer Major ecological transitions in wild sunflowers facilitated by hybridization. Science 301: Robertson, J.H., R.E. Eckert, and A.T. Bleak Responses of grasses seeded in an Artemisis tridentata habitat in Nevada. Ecology 47: Robins, J.G., K.B. Jensen, T.A. Jones, B.L. Waldron, M.D. Peel, C.W. Rigby, K.P. Vogel, R.B. Mitchell, A.J. Palazzo, and T.J. Cary Stand establishment and persistence of perennial cool-season grasses in the Intermountain West and the Central and Northern Great Plains. Rangeland Ecology & Management 66: Rogler, G.A Response of geographical strains of grasses to low temperatures. Agronomy Journal 35: Schrotenboer, A.C., M.S. Allen, and C.M. Malmstrom Modification of native grasses for biofuel production may increase virus susceptibility. GCB Bioenergy 3: Natural Areas Journal Volume 35 (1), 2015