1 ABSTRACT

The following revegetation/restoration plan was prepared for the Ash Meadows National Wildlife Refuge (AHME). This plan describes measures to establish desired native plants within the footprint of proposed channel reconstructions in the Upper Carson Slough and Crystal Spring Management Units. Additionally, this plan describes measures to remove non-native, invasive species that, if left untreated, could reduce native species establishment and survival throughout the AHME. The treatment of non-native, invasive species includes areas where monocultures of these plants have developed, as well as a few sites that have potential for invasion following restoration actions such as the removal or modification of Crystal and Peterson Reservoirs. This document also includes plans for planting the former Mud Lake Reservoir and abandoned agricultural fields that have been slow to recover.

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TABLE OF CONTENTS

1 Abstract ...... i 2 Introduction ...... 1 3 Prioritization of Revegetation and Weed Treatments in Conjunction with Spring Restoration Efforts ...... 3 3.1 Historical Conditions...... 5 3.1.1 Disturbance Regimes ...... 14 3.2 Existing Conditions ...... 14 3.3 Desired Future Conditions ...... 15 4 Phases of Wetland Revegetation...... 25 4.1 Plant Propagation ...... 25 4.2 Plant Salvage ...... 31 4.3 Weed Treatment and Revegetation Efforts ...... 32 4.3.1 Weed Removal ...... 32 4.3.2 Coordination of Weed Removal Efforts ...... 51 4.3.3 Additional Weed Concerns ...... 52 4.4 Preparation of the Soil Surface...... 53 4.5 Planting and Irrigation ...... 54 4.5.1 Planting ...... 54 4.5.2 Irrigation ...... 55 4.6 Monitoring and Further Weed Removal Efforts ...... 56 5 Upper Carson Slough ...... 57 5.1 Weed Treatments within Upper Carson Slough ...... 59 5.2 Fairbanks Spring Channel ...... 61 5.3 Soda Spring Channel ...... 64 5.4 Rogers Spring Channel...... 67 5.5 Longstreet Spring Channel ...... 70 5.6 Five Springs Channel ...... 76 6 Crystal Spring Management Unit ...... 79 6.1 Weed Treatments within the Crystal Spring Management Unit ...... 81 6.2 Forest and Kings Spring Channels ...... 81 6.3 Bradford Spring Channel ...... 85 6.4 Crystal Spring Channel ...... 88 7 Revegetation following Reservoir Modifications or Removals ...... 92 7.1 Crystal Reservoir ...... 92 7.2 Mud Lake Dam Reservoir ...... 95 7.3 Peterson Reservoir...... 97 8 Revegetation of Abandoned Agricultural Fields ...... 99 8.1 Soil Assessment and Amendments ...... 99 8.2 Planting...... 100 8.3 Irrigation ...... 100

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8.4 Monitoring of Revegetation Efforts ...... 101 8.5 Agricultural Field Selection for Active Revegetation ...... 101 8.6 Point of Rocks ...... 103 8.7 Longstreet ...... 105 9 Conclusion ...... 108 10 Literature Cited ...... 109

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2 INTRODUCTION

The following revegetation/restoration plan describes methods to establish desired native plants throughout the Ash Meadows National Wildlife Refuge (AHME). AHME is located east of Death Valley National Park and south of Amargosa Valley, NV (Figure 2-1). Habitat restoration activities are ongoing at AHME, and plans for future restoration projects are in development. This revegetation plan is designed to allow managers to prepare for and implement these projects.

Revegetation efforts hasten the habitat restoration process and are especially important in arid habitats, where plant succession is slow. Additional benefits of revegetation include reduced soil erosion, improved streambank stability, improved upland and riparian wildlife habitat, and decreased spread of non-native, invasive plants. Active revegetation of wetland areas and weed treatments are the highest priority. These actions will have the greatest positive effect on establishing and maintaining native plants throughout the AHME.

In order to formulate this plan, historical environmental conditions, existing vegetation types, and desired future conditions were explored. We focused extensively on weed distributions and removal strategies because weeds are often the biggest hurdle in restoration efforts. This plan provides details for propagation and planting of desired species and suggestions for soil amendments for revegetation of abandoned agricultural fields. A general monitoring protocol is also suggested. This revegetation plan will require refinement in the near future because restoration plans are still in development for most of these areas.

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Figure 2-1. Location of Ash Meadows National Wildlife Refuge (outlined in red).

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3 PRIORITIZATION OF REVEGETATION AND WEED TREATMENTS IN CONJUNCTION WITH SPRING RESTORATION EFFORTS

This revegetation plan is intended to complement current and future restoration efforts throughout the AHME and specifically within the Upper Carson Slough (UCS) and Crystal Spring Management Units (CMU). Revegetation efforts and weed treatments are proposed for five spring systems within the Upper Carson Slough Management Unit (Fairbanks, Soda, Rogers, Longstreet and Five Springs) and four springs within the Crystal Spring Management Unit (Bradford, Kings, Forest, and Crystal). Planting recommendations are presented for existing and former reservoirs for which removal or modification is being recommended in the UCS and CMU restoration plans; specifically Crystal, Peterson and Mud Lake Dam Reservoirs. Additionally, the plan prioritizes treatment areas for non-native, invasive plants (i.e., weeds).

Revegetation efforts and weed treatments are prioritized in light of limited funding and the threat of continued invasion by various weeds. Rapid and cost-effective revegetation may include salvage of plant material prior to channel construction and replanting immediately following channel completion. Apart from construction areas, places dominated by weeds throughout Ash Meadows should be treated and planted. Existing weed patches serve as propagule sources resulting in the continued spread of invasive plants. Weed patches that overlap within proposed spring outflow channels are discussed with regard to each respective channel. In most cases, weed removal would be most effective if it was completed prior to the commencement of construction efforts. Construction efforts increase the threat of further weed invasion by clearing land previously occupied by native plants. Therefore, continued weed treatment and revegetation efforts are necessary following channel construction.

If modified or removed, former and existing reservoirs will require active revegetation. If weeds are treated prior to or concurrently with reservoir draining, the likelihood of further invasions will be reduced. At the present time, abandoned agricultural fields are in various stages of passive recovery and in varying degrees of weed invasion. Fields that are slow to recover and have high cover of non-native plants are recommended for weed treatments and active revegetation as funds become available.

Planting within channel construction footprints will be most cost effective and successful if areas of high soil moisture can be planted concurrently with construction efforts. Throughout much of the AHME, native wetland plants are abundant within the vicinity of stream channels, and favorable environmental conditions, especially high soil moisture, promote further establishment of wetland plants. The rapid establishment of native species will reduce the potential establishment of invasive, non-native species. Active planting efforts and subsequent seed dispersal will also encourage passive establishment of native vegetation within the AHME.

Complete restoration of AHME requires the establishment of both wetland and upland plant communities; however, this will not be achieved quickly or inexpensively. Given that plant establishment in arid and semi-arid environments are responses to exceptional events as opposed to average conditions (Westoby 1980), upland restoration in arid environments is Carson Slough and Crystal Spring Revegetation | Final Report 3 extremely challenging and expensive. Plant succession in these systems may require decades if not longer to establish climax plant communities. Managers should be aware that revegetation of upland communities will be a slower process than wetland revegetation.

Some upland areas will likely become marshes following channel restoration. Postponing the planting of upland areas that are expected to become marshes until areas of high soil moisture have stabilized will avoid costly mistakes. Plants will not survive if they are planted in areas that are too moist or too dry.

Prior to implementation, revegetation projects generally require between one and two years to allow enough time to collect seed, take cuttings and/or otherwise propagate plant materials. Given that only native ecotypes are to be used onsite and that channel construction is already underway, a fraction of ideal planting rates are proposed in this report so that the AHME can implement this plan as quickly as possible with available funds. Ideal planting rates were estimated based on the cover of species reported as defining vegetation alliances by NatureServe (accessed June 30, 2009). This amount of cover can be interpreted as a final goal for active revegetation efforts. Vegetation alliances were identified as being mesic or dry based on whether or not “flooding” was included in the alliance name. Planting rates proposed in this report are 10% of the ideal for mesic alliances and 20% of ideal for dry alliances. Mesic alliance planting rates are less because these plants take less time to increase in cover.

If seed is available, wetland plants can be seeded within the gently sloping, mesic banks near newly constructed channels. This strategy has worked well at School Springs and Fairbanks Spring in AHME (Carl Lundblad, pers. comm.). Seeded Sporobolus also established in a burn area. The area was seeded in May of 2009 and watered daily throughout the summer (Carl Lundblad, pers. comm). If resources are available, this process could be repeated at other sites throughout the AHME. However, seeding is not recommended in the upland areas due to the need to collect large amounts of seed from plants on site, harsh site conditions and limited plant establishment in past seeding efforts in AHME.

If existing seed is abundant, it would be worthwhile to try seeding as an experimental revegetation strategy. In the spring of 2010, quailbush (Atriplex lentiformis) germination was observed at numerous sites throughout AHME. This species favors disturbed sites. Species that favor disturbed sites often act as pioneers, facilitating the establishment of later successional plants. Refuge restoration crews should experiment by planting quailbush and monitoring to determine whether this species facilitates establishment of more desirable species if they are seeded under these readily-established shrubs.

However, given the difficulties of establishing native plants in this ecosystem from seed, this plan focuses on the usage of containerized plants and salvage plant materials. Using mature plants is more likely to result in the successful plant establishment (Bainbridge 2007) and may result in increased species diversity (Middleton et al. 2010).

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3.1 Historical Conditions

Reconstructing historical conditions can be a challenging exercise due to a very limited amount of existing information. Sources examined to reconstruct the vegetative communities of AHME prior to present time include cadastral surveys, previous reports, expedition notes, summaries of plants with ethnobotanical uses, and historic aerial photographs.

Cadastral surveys (i.e., General Land Office surveys) offer some of the earliest accounts of the western United States. They were conducted in accordance with the Public Land Survey System (PLSS) which required that certain features be noted in the survey. These include the distance along a survey line where a settler’s claim, river, creek, swamp, marsh, springs, lakes or pond is crossed. AHME was surveyed in 1881 and 1882 (Figure 3-1). Several of the springs were noted and some of the wetlands were delineated as “marsh” or “swamp”. The surveyor also noted the presence of sagebrush and bunchgrasses. Fine-scale details about the historic vegetation patterns are difficult to discern from the survey data.

Threloff (1992) reviewed the notes associated with the General Land Office (1881-82) surveys and interpreted the flow patterns of the Fairbanks Spring outflow channel. At the time of these suveys, braided (or anastomosing) channels flowed out of Fairbanks, Roger, and Longstreet Springs to create a slough. The construction of a concrete water control structure in 1925 altered the hydrology of AHME for irrigation. A change in vegetation would have resulted from this change in hydrology. Based on the historical description of this area compared with other sites with similar hydrology, it is likely that this site would have supported more meadow vegetation at the time of the 1881-82 surveys.

Threloff (1992) discusses several other anthropogenic disturbances and changes in vegetation that have occurred within the refuge. For example, in 1966 peat was mined which involved draining the wetlands and removing the top six feet of substrate. In 1969 land was cleared and leveled for agriculture and spring outflows were modified for irrigation. All of these disturbances resulted in reduced area and connectivity of wetland landscapes in AHME.

Threloff (1992) also addresses an increase in cattails within AHME. Botanist Frank Coville, who was part of the Death Valley Expedition, noted that cattails “occurred sparingly” at several locations, a large contrast to the 300+ acres currently dominated by Typha (Bio-West 2010). Threloff conjectures that the climax plant community of these desert springs consists of bulrush, grasses, and sedges.

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Figure 3-1. Cadastral surveys of the Ash Meadows National Wildlife Refuge from 1881 and 1882.

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The Death Valley Expedition of 1891 provides a detailed account of the location and abundance of shrubs and trees observed at that time within AHME and the nearby vicinity (Table 3.1). Within Ash Meadows, explorers found abundant Atriplex confertifolia, Atriplex hymenelytra and Atriplex parryi occurring in alkaline areas. They made note of Fraxinus velutina, Salix exigua and Pluchea sericea commonly occurring in and around the springs, as well as a general abundance of Prosopis glandulosa and Prosopis pubescens. Within a broader radius of AHME (approximately 50 miles; refer to labeled regions in Figure 3-1), we find mention of Atriplex confertifolia, Atriplex polycarpa, Ephedra nevadensis, Hymenoclea salsola, Krameria erecta, Larrea tridentata and Sarcobatus vermiculatus, all occurring commonly in lowland areas.

A number of Native American tribes traditionally resided within the vicinity of AHME. While many tribes traveled to the area for seasonal subsistence, the Southern Paiute and Western Shoshone were thought to be the most permanent year-round residents (Figure 3-2) (Fowler 1986; Rhode 2002). Ethnobotanical accounts detailing those tribes’ uses of regional plants give us some idea of species historically occurring in the area. Prominent species used by local tribes and slated for current revegetation efforts include Juncus balticus, Distichlis spicata, Lycium andersonii, and Anemopsis californica, among many others; 70% of the species suggested for revegetation efforts are mentioned in the Death Valley Expedition and/or ethnobotanical accounts as being historically present in the region, with approximately 10% specified as occurring in Ash Meadows.

Ethnobotanical accounts of Helianthus annuus, or common sunflower, are an interesting point to consider within the question of common sunflower’s nativity. While Helianthus annuus thrives on disturbance and appears ‘weedy’ throughout AHME, ethnobotanical accounts list it as a food source for every tribe historically residing in the area (Fowler 1986). Common sunflower is classified as native by the USDAplants database, with no control measures given for Nevada or any other western state, and it is not listed by the California Invasive Plant Council as being a species of concern (California Invasive Plants Database accessed August 15, 2011).

This discrepancy between common sunflower’s alleged nativity and its weedy behavior may be due to the fact that Helianthus annuus is a species capable of great genetic variability and adaptability. In a 2008 study on the genetics of weedy sunflowers, researchers found that weedy and non-weedy populations grew in close proximity to one another, and that weedy populations had more genetics in common with adjacent wild populations than with other weedy stands that were farther away (Kane and Riesberg 2008). They interepreted this to mean that weediness had likely evolved many times within the species.

Regardless of possible or historic nativity, Helianthus annuus forms dense stands throughout present-day AHME that may displace endemic species (C. Baldino, pers. comm.). Common sunflower is therefore a species of concern, and its treatment is discussed in more detail in “Section 4.3; Weed Treatment and Revegetation Efforts.”

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Figure 3-2. Locations of Native American tribal lands in the vicinity of Ash Meadows. Sources = Fowler (1986) and Rhode (2002).

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Table 3.1 Plants of Ash Meadows National Wildlife Refuge. The nativity, Native American tribes who used these plants, and location of Death Valley Expedition observations within a 50-miles radius of AHME are given. PU= Paiute; S= Shoshoni; OVP= Owens Valley Paiute; PN= Panamint; WS= Western Shoshone; C= Chemhuevi; K= Kawaiisu; NP= Northern Paiute; NSP = Nevada Southern Paiute; U= Unspecified; NNP= Nevada Northern Paiute; WA= Washoe. Sources = Fowler (1986), Merriam (1893), Moerman (2009), and Rhode (2002).

Species Status Used by Tribes Found in Death Valley Expedition (w/in 50 mi of AMNWR) Ephedraceae (Mormon Tea) Ephedra nevadensis Native PU, S, OVP, PN Pahrump Valley, Indian Spring Valley Amaranthaceae (Amaranth) Amaranthus blitoides Native K Amaranthus retroflexus Introduced K Anacardiaceae (Sumac) Rhus trilobata Native P, NSP, WS, C Apocynaceae (Dogbane) Amsonia tomentosa Native OVP Apocynum cannabinum Native PU, NSP, C, OVP, WS Asclepidaceae (Milkweed) Asclepias erosa Native OVP, WS, PN Asclepias fascicularis Native OVP, WS, PN Asclepias speciosa Native PU, OVP, WS, PN Asteraceae (Sunflower) Aster subulatus var. ligulatus Native K Chaetadelpha wheeleri Native NNP Chrysothamnus nauseosus Native S, WS Cirsium mohavense Native WS, PU, NSP, C, OVP, PN Encelia farinosa Native WS, PU, NSP, C Encelia viginensis Native K Enceliopsis nudicaulis var. corrugata Threatened S Gutierrezia microcephala Native WS Helianthus annuus Native P, OVP, PN, WS, K, WA, NP Iva axillaris ssp. robustior Native PU, S Pluchea sericea Native PU, NSP, C, PN Ash Meadows, Pahrump Valley, Death Valley Porophyllum gracile Native PU, S

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Species Status Used by Tribes Found in Death Valley Expedition (w/in 50 mi of AMNWR) Psathyrotes annua Native PU, S, C, NSP, WS, OVP Psathyrotes ramosissima Native PU, S, C, NSP, WS, OVP Stephanomeria pauciflora var. ? Native PU, NSP, C Xanthium strumarium Native NP Xylorhiza tortifolia var. tortifolia Native U Boraginaceae (Borage) Amsinkia tesselata Native PN, K, PU, NSP, C, WS, OVP Heliotropium curvassavicum Native PU, S Brassicaceae (Mustard) Descurainia pinnata Native PU, NSP, OVP, PN, C, WS, NP, WA Descurainia sophia Introduced PU, NSP, OVP, PN, K, NP Lepidium lasiocarpum var. lasiocarpum Native K Physaria chambersii Native PU, S Stanleya pinnata var. ? Native PU, S, NSP, C, PN, WS, K, Oasis Valley NNP Thelypodium integrifolim ssp. affine Native PU, NSP, C, OVP Cactaceae (Cactus) Echinocactus polycephalus Native PU, NSP, C, PN, K, OVP Indian Spring Valley, Ash Meadows Echinocereus engelmannii Native PN, PU, NSP, C Opuntia basilaris var. basilaris Native S, PN, K, PU, NSP, C, WS, OVP, WA Opuntia echinocarpa Native P, NSP, C, WS Death Valley, Pahrump Valley Opuntia ramosissima Native Indian Spring Valley Chenopodiaceae (Goosefoot) Allenrolfea occidentalis Native NNP Death Valley Atriplex canescens ssp. Canescens Native S, PU, NSP, C, OVP, WS Oasis Valley, Indian Spring Valley, Pahrump Valley Atriplex confertifolia Native NP, NSP, PU, C Oasis Valley, Indian Spring Valley, Pahrump Valley, Ash Meadows Atriplex hymenelytra Native Death Valley, Ash Meadows, Oasis Valley, Amargosa Canyon Atriplex lentiformis ssp. torreyi Native Amargosa Canyon Atriplex parryi Native Ash Meadows, Oasis Valley Atriplex polycarpa Native Oasis Valley, Pahrump Valley Chenopodium album Introduced PU, OVP, PN, WS, K, NP Grayia spinosa Native Oasis Valley

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Species Status Used by Tribes Found in Death Valley Expedition (w/in 50 mi of AMNWR) Krascheninnikovia lanata Native P, S, WS, PN Sarcobatus vermiculatus Native P, NP Oasis Valley Suaeda moquinii Native PU, S, NSP, C, WS, OVP Cucurbitaceae (Gourd) Cucurbita palmata Native WS Euphorbiaceae (Spurge) Chamaesyce albomarginata Native S, PU, NSP, C, OVP, WS, K Chamaesyce polycarpa Native S Fabaceae (Legume or Pea) Acacia greggii Native NSP, C Prosopis glandulosa var. torreyana Native K, OVP, PU, NSP, C, PN, WS Death Valley, Amargosa Canyon, Ash Meadows, Indian Spring Valley Prosopis pubescens Native PU, NSP, C, OVP, PN, WS Death Valley, Amargosa Canyon, Ash Meadows, Indian Spring Valley Psorothamnus fremontii var. fremontii Native P, S, C, NSP, WS, OVP Krameriaceae (Rhatany) Krameria erecta Native PU, NSP, C, WS Krameria grayi Native PU, S Lamiaceae (Mint) Marrubium vulgare Introduced PU, K Salazaria mexicana Native Oasis Valley, Indian Spring Valley Salvia columbiariae Native PU, NSP, C, OVP, PN, WS, K Salvia dorrii Native PU, NP, S, NSP, C, OVP, WS, K Loasaceae (Loasa) Eucnide urens Native South Desert Ranges Lythraceae (Loosestrife) Lythrum californicum Native K Malvaceae (Mallow) Sphaeralcea ambigua Native S, WS, PU, NSP, C, OVP, PN Nyctaginaceae (Four o'clock) Mirabilis bigelovii Native PU Oleaceae (Olive) Fraxinus velutina Native PU, NSP, K, C, OVP Menodora spinescens Native Oasis Valley, Indian Spring Valley Onagraceae (Evening Primrose)

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Species Status Used by Tribes Found in Death Valley Expedition (w/in 50 mi of AMNWR) Oenothera elata ssp. hirsutissima Native OVP, PN Papaveraceae (Poppy) Argemone corymbosa Native PU, NSP, K, C, OVP, WS Plantaginaceae (Plantain) Plantago major Introduced PU, S, K Plantago ovata Native WS Polemoniaceae (Phlox) Eriastrum eremicum ssp. eremicum Native PU Polygalaceae (Milkwort) Polygonaceae (Buckwheat) Chorizanthe rigida Native Death Valley, Amargosa Desert, Oasis Valley, Indian Spring Valley Eriogonum inflatum var. deflatum Native K, OVP, PU, NSP, C, PN, WS Eriogonum inflatum var. inflatum Native K, OVP, PU, NSP, C, PN, WS Rumex crispus Introduced PU, NP, S, OVP, PN, WS, K, NNP Rumex hymenosepalus Native P, WS, K Ranunculaceae (Buttercup) Delphinium parishii ssp. parishii Native PN, OVP, K Rutaceae (Rue) Thamnosma montana Native PU, S, NSP, C, PN, WS, K Indian Spring Valley Salicaceae (Willow) Populus fremontii ssp. Fremontii Native K Pahrump Valley Salix exigua Native NP, OVP, PU, NSP, C, PN, Death Valley, Amargosa Canyon, Ash Meadows WS Salix gooddingii Native, OVP, PU, NSP, C, PN, WS possibly cultivated Sauraceae (Lizard's Tail) Anemopsis californica Native PU, S, OVP, NSP, C, PN, WS, K Scrophulariacae (Snapdragon) Castilleja angustifolia Native OVP, PU, NSP, C, PN, WS Castilleja linariifolia Native S, OVP, PU, NSP, C, PN, WS Mimulus guttatus Native S, K Solanaceae (Nightshade)

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Species Status Used by Tribes Found in Death Valley Expedition (w/in 50 mi of AMNWR) Datura wrightii Native PU, S, WS, OVP, NSP, C, K Lycium andersonii Native OVP, PN, WS, PU, NSP, C, Oasis Valley, Amargosa Desert, Indian Spring Valley NNP, WA Nicotiana obtusifolia Native WS, OVP, PU, NSP, C, PN Vitaceae (Grape) Vitus arizonica Native NSP, PN, OVP, PU, C, WS Zygophyllaceae (Caltrop) Larrea tridentata Native PU, S, WS, OVP, NSP, C, PN, Amargosa Desert, Death Valley, Oasis Valley, Indian Spring K Valley, Pahrump Valley Arecaceae (Palm) Washingtonia filifera Introduced WS Cyperaceae (Sedge) Scirpus maritimus Native NSP, NNP Juncaceae (Rush) Juncus balticus Native OVP, NSP, PU, C, WS Liliacae (Lily) Calochortus flexuosus Native WS, OVP, NSP, PU, C, PN, K Dichelostemma capitatum Native WS Yucca schidigera Native OVP, NSP, PU, C Poaceae Achnatherum hymenoides Native NSP, C, OVP, PN, WS, K, PU Distichlis spicata Native NSP, C, OVP, K, PU Echinochloa crusgalli Introduced OVP Leymus cinereus Native NSP, C, OVP, K, PU Muhlenbergia asperifolia Native NSP, C Phragmites australis Native PU, NSP, C, OVP, PN, WS, K Sporobolus airoides Native NSP, OVP, PN Typhaceae (Cattail) Typha domingensis Native OVP, K, PU, NSP, C, WS, NNP

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3.1.1 Disturbance Regimes Persistence of plant communities on the landscape requires adaption to the severity and frequency of disturbance. Knowledge of current and historic disturbance regimes is useful for understanding existing vegetation patterns as well as informing plans for future vegetation.

At AHME, fire regime contributes significantly to vegetation patterns. To gain insight into these patterns, an Ecological Niche Factor Analysis was used to model burning probability and severity within the refuge (Sunderman and Weisberg, in review). While fire regime can contribute to vegetation composition by selecting for resprouting plants, vegetation structure also contributes to burn probability. Dense heterogenous pre-fire vegetation (most often riparian forest and emergent wetlands) occurring near anthropogenic ignition sources has the greatest burn probability (Sunderman and Weisberg, in review). Burn severity is highest in homogenous vegetation types dominated by woody species, especially riparian forest. In contrast, desert upland vegetation types with low fuel connectivity and availability have low burn probability and low burn severity.

A fire history analysis was conducted for Ash Meadows, focusing on fires that occurred between 1980 and 2008 (Sunderman 2009). Use of remote sensing techniques successfully reconstructed nine of fifteen recorded wildfire events. Of the six fires omitted by the remote sensing technique, five fires were less than one acre in size. The analysis revealed that 12.3% of AHME burned and 19.8% of the burned area burned twice. Most of the burning within this time period was low-severity fire (93%), where as only 7% was high severity. Tendency of low severity fire is common in riparian areas of the western US, and many riparian plants resprout soon after fires due to adaptations for flood disturbance (Dwire and Kauffman 2003). At AHME, frequent, low severity fires may select for plants that are capable of resprouting.

Fire severity and frequency information as well as historic spatial patterns of fire on the refuge can be incorporated into revegetation efforts. Sunderman and Weisberg (In Review) caution that planting trees such as willow and ash may increase fire severity. However, willow and ash were historically abundant around springs (Threloff 1992). Planting to avoid creation of dense, homogenous stands of vegetation near human ignition sources will reduce the likelihood of frequent or severe fire, also reducing the establishment of weeds that thrive after fire.

3.2 Existing Conditions The AHME vegetation map created by Bio-West (2010) and the construction footprints of each proposed restored channel alignment were intersected in ArcGIS 10 to assess which plant communities currently exist within each project area. The area examined was divided into three zones (Figure 3-3). One meter on either side of the channel was estimated as being water. A one meter buffer surrounding the water was expected to have saturated soils appropriate for wetland plants, and the recommended species list for replanting this zone was designed to favor native fish species (see two meter channel buffer in Figure 3-3). An additional

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eight meters on either side of the saturated zone was estimated as containing the construction footprint (see ten meter channel buffer in Figure 3-3).

Proposed target vegetation alliances are summarized with acreages for each channel alignment. These are the same vegetation alliances used in the Bio-West vegetation map, with the exception of the weed-dominated alliances. Cover of individual weedy species was estimated for each channel using the same method as above.

Each vegetation alliance was checked on NatureServe (accessed June 30, 2009) to identify the plants commonly found within the alliance. These commonly associated plants were cross- referenced with a plant list created by Otis Bay Ecological Consultants for Ash Meadows, as well as the current list for the AHME that has been updated by Bio-West (2010), to determine which species would be acceptable for use in revegetation efforts (Table 3.2).

3.3 Desired Future Conditions Desired future conditions are long-term project goals that are initiated by revegetation of project areas. Planting recommendations are based upon existing plant communities, with some exceptions where plant communities are non-native (e.g., Tamarix Semi-Natural Temporarily Flooded Shrubland Alliance) or undesirable (Non-native Helianthus) (Table 3.2). Proposed replacement plant communities for sites dominated by non-native species are suggested based upon disturbance and environmental conditions as well as an ability to compete with weedy species.

The period of time required to attain these desired conditions varies by habitat type, and given the extreme growing conditions in the Mojave Desert, some areas may take decades to obtain climax stage canopy cover of native species. The relevance of ecological succession theory to desert systems is uncertain because plant distribution and dominance is influenced primarily by tolerance to harsh environments and less affected by biotic interactions such as competition (Webb et al. 2009). For example, communities dominated by Sueda moquinii are highly saline, and when disturbances occur, Sueda usually recolonizes the area (Thomas et al. 2004). Succession in desert spring systems is even more poorly understood. Therefore, in most situations we recommend planting species that are desired in the long-term instead of planting early successional species that might eventually phase into desired plant communities.

Areas within close proximity to the restored channel alignments should have sufficient soil moisture to fully recover within a few years of planting. The size and maturity of initial plantings will affect the rate at which potential communities establish following revegetation efforts. Therefore, mesic riparian vegetation areas that are planted with 3-4” potted plants will likely provide enhanced habitat in as soon as a few years. All other areas should be planted with #1 size container plants (industry term; actual capacity is roughly 0.75 gallons) to improve success rates under more difficult growing conditions.

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Figure 3-3. Depiction of methods used for vegetation assessment. The e isting vegetation alliances within the -m and -m buffers around proposed channel restorations were determined using GIS and the Bio-West (2010) vegetation map.

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Table 3.2. Existing plant alliances and replacement species for restoration areas. The relative percent cover, recommended number of plants per acre, appropriate soil pH, and approximate cost of plant materials per acre are given. Planting densities are estimated based on cover at maturity for species. Three plant mixtures that are variations of existing alliances are recommended.

Relative Salinity Range of Alliance Name/Planting Mix Species Percent Cover Number Tolerance Soil pH Cost per acre Atriplex canescens Shrubland $2,227.01 Achnatherum hymenoides 7 102 Low 6.6-8.6 $304.92 Aristida purpurea 7 102 Low 5.5-7.5 $304.92 Atriplex canescens 50 245 High 6.5-9.5 $735.08 Ephedra nevadensis 7 57 Moderate 7.0-8.5 $171.52 Grayia spinosa 10 82 High 6.5-9.0 $245.03 Kraschninnikova lanata 7 57 High 6.6-8.5 $171.52 Lycium pallidum 7 57 Low 7.0-8.5 $171.52 Psorothamnus fremontii 5 41 Unknown Unknown $122.51

Atriplex confertifolia Shrubland $1,979.26 Ambrosia dumosa 5 41 Moderate 7.0-8.5 $122.51 Atriplex confertifolia 50 245 High 7.5-9.0 $735.08 Atriplex polycarpa 5 41 High 7.5-9.0 $122.51 Ephedra nevadensis 2 16 Moderate 7.0-8.5 $49.01 Eriogonum heermannii 1 15 Unknown 5.0-8.0 $43.56 Grayia spinosa 5 41 High 6.5-9.0 $122.51 Gutierrezia microcephala 2 16 Unknown 6.8-7.5 $49.01 Krascheninnikovia lanata 5 41 High 6.6-8.5 $122.51 Larrea tridentata 15 123 Unknown 7.0-8.5 $367.54 Lycium andersonii 5 41 Low 6.0-8.0 $122.51 Sarcobatus vermiculatus 5 41 High 7.5-8.5 $122.51

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Relative Salinity Range of Alliance Name/Planting Mix Species Percent Cover Number Tolerance Soil pH Cost per acre Atriplex confertifolia - Isocoma acradenia Shrubland $2,450.25 Ambrosia dumosa 5 41 Moderate 7.0-8.5 $122.51 Atriplex confertifolia 25 204 High 7.5-9.0 $612.56 Atriplex polycarpa 5 41 High 7.5-9.0 $122.51 Ephedra nevadensis 5 41 Moderate 7.0-8.5 $122.51 Eriogonum heermannii 5 41 Unknown 5.0-8.0 $122.51 Grayia spinosa 5 41 High 6.5-9.0 $122.51 Gutierrezia microcephala 5 41 Unknown 6.8-7.5 $122.51 Isocoma acradenia 25 204 Unknown Unknown $612.56 Krascheninnikovia lanata 5 41 High 6.6-8.5 $122.51 Larrea tridentata 5 41 Unknown 7.0-8.5 $122.51 Lycium andersonii 5 41 Low 6.0-8.0 $122.51 Sarcobatus vermiculatus 5 41 High 7.5-8.5 $122.51

Atriplex lentiformis Shrubland $1,976.54 Ambrosia dumosa 5 41 Moderate 7.0-8.5 $122.51 Atriplex canescens 5 41 High 6.5-9.5 $122.51 Atriplex lentiformis 50 245 High 7.0-10 $735.08 Distichlis spicata 10 145 High 6.4-10 $261.36 Hymenoclea salsola 5 41 Unknown Unknown $122.51 Isocoma acradenia 5 41 Unknown Unknown $122.51 Larrea tridentata 15 123 Unknown 7.0-8.5 $367.54 Prosopis glandulosa 5 41 Low 7.0-8.5 $122.51

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Relative Salinity Range of Alliance Name/Planting Mix Species Percent Cover Number Tolerance Soil pH Cost per acre Atriplex parryi Shrubland $2,227.01 Achnatherum hymenoides 7 102 Low 6.6-8.6 $304.92 Aristida purpurea 7 102 Low 5.5-7.5 $304.92 Atriplex parryi 50 245 High Unknown $735.08 Ephedra nevadensis 7 57 Moderate 7.0-8.5 $171.52 Grayia spinosa 10 82 High 6.5-9.0 $245.03 Kraschninnikova lanata 7 57 High 6.6-8.5 $171.52 Lycium pallidum 7 57 Low 7.0-8.5 $171.52 Psorothamnus sp. (fremontii) 5 41 Unknown Unknown $122.51

Baccharis emoryi Intermittently Flooded Shrubland $2,129 Baccharis emoryi 60 245 Moderate 6.0-8.5 $735.08 Distichlis spicata 10 145 High 6.4-10 $261.36 Juncus balticus 10 146 Moderate 6.0-9.0 $261.36 Sporobolus airoides 20 290 High 6.6-9.0 $871.20

Chrysothamnus albidus Shrubland $1,606.28 Aristida purpurea 10 145 Low 5.5-7.5 $435.60 Chrysothamnus albidus 80 245 Unknown Unknown $735.08 Poa secunda 10 145 Low 6.5-8.2 $435.60

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Relative Salinity Range of Alliance Name/Planting Mix Species Percent Cover Number Tolerance Soil pH Cost per acre Distichlis spicata Intermittently Flooded Shrubland $2,570.04 Distichlis spicata 55 436 High 5.3-6.8 $784.08 Hordeum jubatum 5 73 High 5.0-7.2 $130.68 Iva axillaris 5 73 High Unknown $217.80 Juncus balticus 5 73 Moderate 6.0-9.0 $130.68 Muhlenbergia asperifolia 15 218 High 6.0-8.4 $653.40 Sporobolus airoides 15 218 High 6.6-9.0 $653.40

Distichlis spicata mixture $2,580.93 Distichlis spicata 50 436 High 6.4-10 $784.08 Muhlenbergia asperifolia 15 218 High 6.0-8.4 $653.40 Sporobolus airoides 15 218 High 6.6-9.0 $653.40 Atriplex canescens 10 82 High 6.5-9.5 $245.03 Atriplex confertifolia 10 82 High 7.5-9.0 $245.03

Ericameria nauseosa Shrubland $2,480.20 Achnatherum hymenoides 10 145 Low 6.6-8.6 $435.60 Atriplex canescens 10 82 High 6.5-9.5 $245.03 Distichlis spicata 10 145 High 5.3-6.8 $261.36 Ericameria nauseosa 45 245 Unknown 7.5-8.7 $735.08 Gutierrezia microcephala 5 41 Unknown 6.8-7.5 $122.51 Psorothamnus fremontii 5 41 Unknown Unknown $122.51 Sarcobatus vermiculatus 5 41 High 7.5-8.5 $122.51 Sporobolus airoides 10 145 High 6.6-9.0 $435.60

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Relative Salinity Range of Alliance Name/Planting Mix Species Percent Cover Number Tolerance Soil pH Cost per acre

Fraxinus velutina-Sporobolus $10,534.089, airoides Woodland 411.53 Datura wrightii 5 41 Unknown 6.1-7.8 $122.51 Ericameria nauseosa 5 41 Unknown 7.5-8.7 $122.51 Fraxinus velutina 50 245 Low 5.8-7.5 $8,820.90 Distichlis spicata 10 145 High 5.3-6.8 $261.36 Sporobolus airoides 30 435 High 6.6-9.0 $1206.80

Isocoma acradenia Shrubland Alliance $2,450.25 Ambrosia dumosa 5 41 Moderate 7.0-8.5 $122.51 Atriplex confertifolia 10 82 High 7.5-9.0 $245.03 Atriplex polycarpa 5 41 High 7.5-9.0 $122.51 Ephedra nevadensis 5 41 Moderate 7.0-8.5 $122.51 Eriogonum heermannii 5 41 Unknown 5.0-8.0 $122.51 Grayia spinosa 5 41 High 6.5-9.0 $122.51 Gutierrezia microcephala 5 41 Unknown 6.8-7.5 $122.51 Isocoma acradenia 40 327 Unknown Unknown $980.10 Krascheninnikovia lanata 5 41 High 6.6-8.5 $122.51 Larrea tridentata 5 41 Unknown 7.0-8.5 $122.51 Lycium andersonii 5 41 Unknown 6.0-8.0 $122.51 Sarcobatus vermiculatus 5 41 High 7.5-8.5 $122.51

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Relative Salinity Range of Alliance Name/Planting Mix Species Percent Cover Number Tolerance Soil pH Cost per acre Juncus arcticus Seasonally Flooded $2,613.60 Carex praegracilis 25 363 Low 5.3-6.8 $653.40 Eleocharis rostellata 25 363 Moderate 6.0-8.0 $653.40 Juncus arcticus 5 73 Moderate 6.0-9.0 $130.68 Schoenoplectus americanus 15 218 Moderate 5.9-7.2 $392.04 Schoenoplectus maritimus 15 218 High 4.0-7.0 $392.04 Schoenoplectus robustus 15 218 High 6.4-8.4 $392.04

Prosopis glandulosa Shrubland $2,289.62 Acacia greggii 3 25 None 6.5-8.5 $73.51 Allenrolfea occidentalis 1 8 High 7.3-8.3 $24.50 Ambrosia spp. 2 16 Moderate 7.0-8.5 $49.01 Atriplex canescens 2 16 High 6.5-9.5 $49.01 Atriplex polycarpa 1 8 High 7.5-9.0 $24.50 Croton californicus 1 15 High 6.0-8.0 $43.56 Distichlis spicata 15 218 High 6.4-10 $392.04 Gutierrezia microcephala 3 25 Unknown 6.8-7.5 $73.51 Isocoma acradenia 2 16 Unknown Unknown $49.01 Krascheninnikovia lanata 2 16 High 6.6-8.5 $49.01 Larrea tridentata 2 16 Unknown 7.0-8.5 $49.01 Prosopis glandulosa 50 245 Low 7.0-8.5 $735.08 Sporobolus airoides 15 218 High 6.6-9.0 $653.40 Suaeda moquinii 1 8 High 7.0-8.0 $24.50

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Relative Salinity Range of Alliance Name/Planting Mix Species Percent Cover Number Tolerance Soil pH Cost per acre Prosopis pubescens Woodland $2,428.47 Atriplex canescens 1 8 High 6.5-9.5 $24.50 Atriplex polycarpa 2 16 High 7.5-9.0 $49.01 Baccharis emoryi 10 82 Moderate 6.0-8.5 $245.03 Distichlis spicata 20 290 High 6.4-10 $522.72 Isocoma acradenia 5 41 Unknown Unknown $122.51 Prosopis glandulosa 10 82 Low 7.0-8.5 $245.03 Prosopis pubescens 40 245 High 7.5-9.0 $735.08 Sporobolus airoides 10 145 High 6.6-9.0 $435.60 Suaeda moquinii 2 16 High 7.0-8.0 $49.01

Schoenoplectus americanus Semipermanently Flooded Herbaceous $1,568.16 Schoenoplectus americanus 50 436 Moderate 5.9-7.2 $784.08 Juncus arcticus 25 218 Moderate 6.0-9.0 $392.04 Eleocharis rostellata 25 218 Moderate 6.0-8.0 $392.04

Sporobolus airoides Intermittently Flooded Herbaceous $1,796.85 Allenrolfea occidentalis 1 8 High 7.3-8.3 $24.50 Atriplex lentiformis 1 8 High 6.5-9.5 $24.50 Atriplex canescens 1 8 High 7.0-10 $24.50 Distichlis spicata 5 73 High 6.4-10 $130.68 Poa secunda 6 87 Low 6.5-8.2 $261.36

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Relative Salinity Range of Alliance Name/Planting Mix Species Percent Cover Number Tolerance Soil pH Cost per acre Sporobolus airoides 85 436 High 6.6-9.0 $1,306.80 Suaeda moquinii 1 8 High 7.0-8.0 $24.50

Suaeda moquinii Intermittently Flooded Shrubland $2,096.33 Atriplex polycarpa 5 41 High 7.5-9.0 $122.51 Atriplex canescens 5 41 High 6.5-9.5 $122.51 Allenrolfea occidentalis 5 41 High 7.3-8.3 $122.51 Sarcobatus vermiculatus 5 41 High 7.5-8.5 $122.51 Suaeda moquinii 60 245 High 7.0-8.0 $735.08 Sporobolus airoides 20 290 High 6.6-9.0 $871.20

Multi-Alliance mixture $2,495.99 See DISP_IFH 40 Association $1,028.02 See JUAR2_SFL 40 Association $1,045.44 See PRPU_WD 10 Association $242.85 See SPAI_IFH 10 Association $179.69

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4 PHASES OF WETLAND REVEGETATION

Revegetation efforts will be broken into six phases: 1) plant propagation, 2) plant material salvage, 3) weed treatment and removal, 4) soil surface preparation, 5) planting and installation of irrigation, and 6) monitoring and follow-up weed treatment.

Due to the time necessary for propagation of many plants recommended for revegetation (Table 4.1), plant propagation should be the first consideration in a restoration project. Some plants may need to be grown from seed. Other plant materials can be salvaged prior to, during, or after the initial restoration/construction phase. Initial weed removal efforts such as mowing or spraying should be completed prior to construction activities. Preliminary weed removal will reduce competition with established native species. If necessary, mechanical removal can be completed as part of the initial restoration/construction phase. Disturbance resulting from weed removal will not stress planted species if weeds are removed prior to planting.

Soil surface preparation will typically occur in the finishing/grading/completion phase of construction. Collection and planting of salvage material should occur in late fall, winter, or early spring, when evapotranspiration rates are low, to minimize stress to transplanted individuals (Anderson and Ostler 2002). Plants should only be planted where sufficient soil moisture is present. Salvage material should be firmly pressed into the cleared soil surface and watered thoroughly. Supplemental watering should be used to minimize stress and encourage deep root growth of transplants. Plants should be irrigated throughout the growing season and into the summer. At the end of the growing season, irrigation should be slowly reduced. Irrigation should cease entirely when plants are determined to be well- established by an experienced plant ecologist.

The final restoration phase includes monitoring and subsequent weed treatments. Monitoring for weed resprouting and establishment should begin the month after treatment and continue monthly through the next several growing seasons. If follow-up herbicide treatments are applied, no additional control measures should be implementedfor at least one growing season. This time-period allows herbicides to take full effect while minimizing additional disturbances that could encourage re- sprouting. Some species, such as tamarisk, should not be treated again for two years to promote maximum herbicide effectiveness (Shafroth et al. 2010). If plants are disturbed before herbicides have had full time to take effect, it is recommended that herbicides be re-applied. Monitoring sites regularly will enable staff to make adjustments to each phase before minor problems compound and compromise revegetation efforts.

4.1 Plant Propagation

Native plant material for revegatation efforts may be introduced as salvaged plant material, hardwood cuttings, seed, or containerized plant material. The preferred method will differ depending on species and revegetation location (Table 4.1). Salvaged plant material is removed as a whole plant and planted in containers or directly at the revegetation site. Anemopsis, Carex, and Juncus species are particularly

Carson Slough and Crystal Spring Revegetation | Final Report 25 suitable for this treatment as are any other rhizomatous species. Trees that would otherwise be removed by construction activities may be transplanted as salvaged material.

Hardwood cuttings are taken from the parent plant during the dormant period of late autumn to early spring and planted before bud break in the spring. These dormant cuttings may be stored at temperatures near freezing for a year or more. The cutting is a clone of the parent plant; therefore, cuttings should be collected from many parent plants to increase genetic diversity on the revegetation site. Although the Refuge does not have plans to plant additional willows at this time, Populus and Salix species can be propagated easily using this method should such plants become desired in the future. Hardwood cuttings from one-half inch to four inches or more in diameter will quickly root in springtime if moisture is available. Cuttings should be long enough to reach available soil moisture when planted, leaving at least one node above the soil surface for vegetative growth. Hardwood cuttings may be planted directly at the revegetation site or rooted in containers and then planted.

‘Seed dormancy’ is the term for viable seed that does not germinate even when placed in suitable conditions. Dormancy prevents the plant embryo from germinating at the wrong time of the year. Seed dormancy can be physical, such as a hard seed coat in Prosopis spp., physiological, such as chemical inhibitors in Rosa spp., or a combination of both types of dormancy (MacDonald 1986). Seed should be collected locally in the wild. Collecting local seed has the advantage of obtaining local genotypes more suited to the revegetation location, but the disadvantage of the necessity for seed cleaning. Seed must be cleaned of any fleshy covering, husks, pods, bristles, or awns prior to seeding, as these structures can promote decay, may contain inhibitors to germination, and can clog seeding equipment.

Direct seeding by hand or with a drill-seeder is the method of applying live seed to a prepared seedbed. Preparation could include soil amendment, invasive species treatment, and plowing, disking, chaining, or otherwise creating micro-topography for the applied seed. Direct seeding in the fall allows the seed to utilize winter and early spring soil moisture and usually breaks any seed dormancy through imbibition of water and repeated freeze/thaw cycles. Graminoids are often successfully revegetated in this manner.

Containerized plant material can be grown from seeds, cuttings, or salvaged material. A containerized plant has the advantage of balanced root and vegetative growth, allowing for quicker establishment and therefore suppressing invading species. Supplemental water is usually necessary for the first growing season. If seed must be collected, the total time to produce a containerized plant for outplanting may take two to three years, depending on species and propagation system. If seed is available, this time period can be reduced to one year for some species (Landis and Simonich 1983).

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Table 4.1. Desired plants, preferred revegetation method, and propagation details. * indicates plants that are not currently on the planting list.

Scientific Name Common Habitat Proposed Time Notes Name method of re- needed to introduction grow (plant / (blank=1 salvage) year) Large Shade Trees Fraxinus velutina velvet ash Riparian Plant 1-2 years Propagate from seed; collect woodland in fall; sow in fall for natural stratification Salix gooddingii* Goodding’s Riparian Plant 0 -6 Propagate from hardwood willow woodland months cutting in dormant season; plant cuttings before bud break Shrubs Acacia greggii catclaw Xeroriparian Plant Propagate from seed; collect acacia pods when they begin to split; scarification required Allenrolfea iodinebush Upland Plant Propagate from seed; collect occidentalis Nov.-Dec. when jointed stems at branch ends are brown; sow in winter Ambrosia dumosa white Upland Plant Propagate from seed; leach bursage seed in water for 24 hrs. Amphipappus Fremont’s Upland Plant fremontii chaffbush Atriplex canescens fourwing Upland Plant 6-12 Propagate from seed; collect saltbush months in fall when golden and papery; leach in water 24 hours, may also benefit from 4 hour soak in 3% hydrogen peroxide; stratify seeds at 3 to 5 C for 4 weeks Atriplex shadscale Upland Plant Propagate from seed; collect confertifolia saltbush in fall; leach in running water 24 hours Atriplex quailbush Floodplains, Plant 6 months Propagate from seed; collect lentiformis washes in fall; leach in water 24 hours Atriplex parryi Parry’s saltbush Atriplex polycarpa cattle Upland Plant 6 months Propagate from seed; collect saltbush in fall when seeds turn hard; leach in water 24 hours Baccharis emoryi Emory’s Riparian Plant 6 months Propagate from seed or semi- baccharis hardwood cuttings with 3000 ppm IBA Carson Slough and Crystal Spring Revegetation | Final Report 27

Scientific Name Common Habitat Proposed Time Notes Name method of re- needed to introduction grow (plant / (blank=1 salvage) year) Chrysothamnus whiteflower Upland Plant Propagate from seed albidus rabbitbrush Croton californicus California Upland Plant Propagate from seed; mature croton seed brown with tan spots; leach in water 24 hours and cold stratify for one month Encelia farinosa brittlebush Upland Plant 6 months Propagate from seed; collect in late spring; can be directly sown Encelia virginensis Virgin River Upland Plant 6 months brittlebush Ephedra Mormon tea Upland Plant Propagate from seed, soak in nevadensis 1:4 water bleach solution 1-3 hours, then leach in water 24 hours before planting Ericameria rubber Upland Plant Propagate from seed; nauseosa rabbitbrush germinates at warm temp. Eriogonum Heermann’s Upland Plant heermannii Buckwheat Grayia spinosa spiny Propagate from seed; collect hopsage in spring; can be directly sown Gutierrezia threadleaf Upland Plant microcephala snakeweed Hymenoclea burrobush Upland Plant Propagate from seed; collect salsola in summer; leach in water 4 hours before planting Isocoma alkali Upland Plant Propagate from seed; collect acradenia goldenbush in Oct./Nov. when seeds look fluffy; directly sow and cover with thin layer of soil Krameria erecta littleleaf Upland Plant Propagate from seed; collect ratany in late summer/fall Krameria grayi white ratany Upland Plant Krascheninnikovia winterfat Upland Plant Propagate from seed; collect lanata in fall; chilling at 40 F for 14 days may improve germination; directly sow no deeper than . 5” Larrea tridentata creosote Upland Plant Propagate from seed; collect in late spring when pods begin to split open; leach in water 48 hours before planting

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Scientific Name Common Habitat Proposed Time Notes Name method of re- needed to introduction grow (plant / (blank=1 salvage) year) Lycium andersonii wolfberry Washes Plant Propagate from seed; collect in June when berries have fully matured, leach in water 24 hours before planting Lycium pallidum pale desert- Upland thorn Pluchea sericea arrowweed Riparian Plant Propagate from seed, or woodland/ cuttings in June/July from Mesic young vigorous stems shrubland Prosopis honey Xeroriparian Plant Propagate from seed; collect glandulosa mesquite in fall when pods begin to split; scarification required; plant in fall in well drained soil Prosopis screwbean Xeroriparian Plant Propagate from seed; collect pubescens mesquite in fall; scarification sometimes required; plant in well drained soil; germinate best with warm air/soil temp. Psorothamnus Fremont’s Upland Plant fremontii dalea Rhus trilobata* sumac Riparian Plant 6-12 Propagate from seed, root woodland/ months cutting or softwood cutting; Mesic plant seed in fall/winter for shrubland natural stratification; cold stratify 40-60 days; aqueous extract of charred wood increases germination; intolerant of crowding Salazaria Mexican Upland Plant 8 months leachin water 4 hours, mexicana bladdersage germinate on blotter paper or direct sow Sarcobatus greasewood Upland Plant Propagate from seed; collect vermiculatus in late fall when fruits are brown; cold stratification required Suaeda moquinii Mojave Plant Species appears to be a seablight wetland indicator, Wetland status requested from ACOE; Collect seed in fall Yucca schidigera Mojave yucca Upland Plant

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Scientific Name Common Habitat Proposed Time Notes Name method of re- needed to introduction grow (plant / (blank=1 salvage) year) Forbs Anemopsis yerba mansa Alkaline Plant /Salvage 3-6 Propagate from rhizomes or californica Meadow months stolons with at least one leaf; obligate wetland species Datura wrightii sacred thorn- Upland Plant Propagate from seed; no apple special requirements, sow in fall or spring Iva axillaris povertyweed Alkaline Plant Facultative wetland species; meadow propagate from seed Lepidium desert Upland Plant Propagate from seed; collect fremontii pepperweed when pods have matured and split open; leach in water 4 hours before planting Stephanomeria brownplume Upland Plant pauciflora wirelettuce Graminoids Achnatherum indian Upland Plant Propagate from seed; cold hymenoides ricegrass stratification required; 15D/5N C temp. cycle for germination Aristida purpurea purple three Upland Plant 6 months awn Carex praegracilis field sedge Wet meadow Plant /Salvage 3 months Propagate from seed; collect in late summer Distichlis spicata saltgrass Alkaline Plant /Salvage Propagate from seed; collect meadow in fall; scarification required; leach in water 24 hrs.; sow in spring Eleocharis spikerush Wet meadow Plant /Salvage 3 months Propagate from seed; collect rostellata in fall; cold ,wet stratification 30 days Hordeum jubatum foxtail barley Meadow Plant Juncus arcticus artic rush Wet meadow Plant /Salvage 0-10 Collect seed late summer/fall; (Juncus balticus) months soak seed in water 1-7 days before planting; may benefit from cold stratification; wild plug collection is best method; if no more than 1 ft2 per each 4 ft2 is removed, holes will fill in one growing season Juncus nodosus knotted rush Wet meadow Plant /Salvage 0-10 See J. arcticus months Muhlenbergia scratchgrass Alkaline Plant 3-6 asperifolia meadow months

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Scientific Name Common Habitat Proposed Time Notes Name method of re- needed to introduction grow (plant / (blank=1 salvage) year) Poa secunda Sandberg Upland Plant Propagate from seed; collect bluegrass after dry but before seed heads shatter; no pretreatment required; sow in fall or spring Schoenoplectus bulrush Marsh Plant /Salvage 6 months Propagate from seed; cold americanus stratify for 180 days, germinate at 30 to 32 C in presence of light Schoenoplectus bulrush Marsh Plant /Salvage 6 months Propagate from seed; cold maritimus stratify for 80 days; needs light for germination Schoenoplectus bulrush Marsh Plant /Salvage 6 months See S.americanus and robustus maritimus Sporobolus alkali sacaton Alkaline Plant 3-6 Propagate from seed; collect airoides meadow months in fall; sow seed in late winter/early spring

4.2 Plant Salvage Salvaged plant material, if taken with care, can contribute greatly to planting efforts. To prevent habitat degradation, transplants taken from existing vegetation should constitute no more than 10% of the vegetative surface area. Transplant removal should be widely spaced and holes should be filled or tapped in.

Mats of grasses, sedges and donor soils up to 8 ft square and 6 inches deep can be cut with shovels, an excavator, or a small front-end loader. Mats should be moist and well drained at the time of cutting in order to prevent the sod from falling apart during collection. Mats should be placed on prepared soil surfaces and secured with wooden stakes.

Carex praegracilis, Eleocharis rostellata, Juncus arcticus and Scirpus spp. (Schoenoplectus) can be effectively salvaged by digging up rhizomes. Rhizomes can be excavated and split into sections. Care should be taken to collect samples that are young and have at least one viable node per section. Collected propagules of these species can be raised as containerized plugs.

Baccharis, mesquite and ash can be salvaged with an excavator and placed into pots until it is time to plant them. When transplanted, they must be watered and placed low enough in pre-formed holes to allow the roots to be in contact with moist soil.

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It is likely that more plants will be needed for the revegetation of channel alignments than will be available. Use of salvage material will ensure that fewer spaces are subjected to erosion, degradation, and weed invasion.

4.3 Weed Treatment and Revegetation Efforts This plan prioritizes treatment for the following non-native invasive plants: Acroptilon repens (Russian knapweed), Bassia hyssopifolia (fivehorn bassia), Cardaria draba (hoary cress), Centaurea melitensis (Malta starthistle), Cynodon dactylon (Bermudagrass), Phragmites australis (common reed), and Tamarix species (saltcedar). Control methods for many of these plants were described in the “Intergrated Pest Management Plan for Ash Meadows National Wildlife Refuge” (USFWS 2006a), and this report builds upon that knowledge. Cardaria draba (hoary cress) and Centaurea melitensis (Malta starthistle) are known to occur within the AHME but have not been observed within channel construction footprints. Therefore, treatment recommendations are given although per acre costs estimates are not. Similarly, coverages of Russian thistle (Salsola paulsenii) and annual rabbitsfoot grass (Polypogon monspeliensis) are included whenever they occurred within a channel footprint, but treatment recommendations and cost estimates are not given because these are not species of high priority. Other plants discussed as having the potential to threaten native plant populations throughout AHME include Elaeagnus angustifolia (Russian olive), Sisymbrium irio (London rocket), Solanum elaeagnifolium (silverleaf nightshade), Sorghum halepense (Johnsongrass), Tribulus terrestris (puncturevine), and Typha species (cattails).

In a recent study, Helianthus annuus (common sunflower) treated as weeds in agricultural fields demonstrated up to a 70% tolerance for herbicide, whereas neighboring wild sunflowers had almost no tolerance (Kane and Riesberg 2008). Given that the difference between native and weedy sunflower populations may be highly localized and difficult to decipher, and the fact that herbicide treatment may increase common sunflower’s weedy characteristics, Helianthus annuus is not slated for active weed treatments within this plan. However, in light of commons sunflower’s weedy characteristics within AHME, patches that occur within channel reconstruction alignments should be replanted with vegetation alliances that will discourage Helianthus annuus from vigorous regrowth.

4.3.1 Weed Removal Minimizing disturbance during construction and weed removal efforts will leave soils and seedbanks intact and facilitate the passive recovery of native plant communities. Given the sensitivity of endemic flora and aquatic fauna, the Integrated Pest Management Plan for the AHME prohibits the use of biocontrols. Following the philosophy of weed control in Yellowstone National Park, herbicide use would best be limited to either areas where aggressive, high priority species do not respond well to mechanical control or to events where staffing for mechanical control is limited (Olliff et al. 2001).

4.3.1.1 Acroptilon repens (Russian knapweed) Acroptilon repens, or Russian knapweed, dominates 6.5 acres within the Upper Carson Slough and 142 acres within the Crystal Spring Management Units (Bio-West 2010). Some of the larger infestations are within close proximity to the proposed Bradford Spring Channel alignment. This species aggressively invades plant communities such as riparian areas, grasslands and woodlands, and contains allelopathic 32 Otis Bay Ecological Consultants

chemicals that give it a strong competitive advantage over native vegetation. The California Invasive Plant Council rates it as being a moderate threat to native plant communities (California Invasive Plants Database accessed August 15, 2011). The following recommended treatment options for Russian knapweed are summarized as a per acre cost in Table 4.2.

Tillage and mechanical removal of Russian knapweed is not advised as individuals readily resprout and each root fragment can grow a new plant. Additionally, fire may encourage knapweed establishment and growth if site conditions are not assessed before burning. Herbicide application is necessary for the control of this species.

Removing this species from the AHME is likely to require many treatments. Applications of aminopyralid at 0.05 kg acid equivalent/ha, applied after seed set, have been shown to control more than 90% of the knapweed within a given patch (Enloe et al. 2008). Aminopyralid is a low-risk herbicide according to the Environmental Protection Agency, meaning that it can be used up to the water’s edge. Dead material should be removed or mowed away from individuals before herbicide application to maximize the amount of chemical that comes into contact with each plant. The site should be evaluated for knapweed mortality the following growing season. If additional treatment is needed, solarization is recommended. Solarization involves mowing the weeds in late winter to within four inches of the soil surface, moistening the area, and covering it with clear plastic that is preferably 2 mm but up to 4 mm thick. The edges of the plastic should be buried under soil to hold the sheet in place and it should be left undisturbed throughout the hottest months of the year. Solarization concentrates heat from the sun into the soil, killing weeds, seeds, and soilborne pathogens. Solarization is especially recommended for hot climates, and thicker plastic is recommended for windy places. Considering the climatic extremes of the desert, a small pilot plot may be used to test the durability and effectiveness of solarization in Ash Meadows. If proven effective, additional follow-up treatments should alternate between herbicide application and solarization.

Following control of Russian knapweed, active revegetation efforts may require tillage of the soil before planting to eliminate allelopathic chemicals produced by the weed. Competitive plants such as perennial grasses are advised for revegetation efforts to hinder reinvasion by non-native plants.

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Table 4.2. Per Acre Treatment Costs of Acroptilon repens.

Action Equipment, Cost Cost per acre Total Cost Notes Supplies, and (of Equipment, per year to eradicate Labor Supplies and Labor) Herbicide Milestone® VM $366 / gal $20 per acre $40 / acre It is assumed that each acre will be treated twice with Application per year herbicide and once with solarization. Follow-up treatments Liberate w/ leci will be necessary after three years, but with reduced weed tech (Non-ionic $30 / gal $3.75 per $7.50 / acre cover, the costs of each subsequent year should be a fraction surfactant) acre per year of the previous year’s cost.

Turf Trax $32 / gal $7.50 / acre $15 / acre Plants should be sprayed to wet. We have assumed an (blue dye) application volume of 30 gallons per acre.

Certified $760 / day $380 / acre $760 / acre No more than 7 fl. oz. should be applied per acre per year. Applicator This is the recommended application rate in the literature.

Surfactant addition has been calculated at 1.5 qt per 100 gal of spray.

1 oz of dye should be used per gallon of spray.

It is assumed that 2 acres a day can be covered with a broadcast sprayer. Mowing Tractor $225 / day $45 / acre $90 / acre Mowing should occur once a year: prior to herbicide application the first year and prior to solarization the second Brush-hog $95 / day $19 / acre $38 / acre year.

It is assumed that 5 acres can be mowed in a day.

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Table 4.2. Per Acre Treatment Costs of Acroptilon repens. (continued)

Action Equipment, Cost Cost per acre Total Cost Notes Supplies, and (of Equipment, per year to eradicate Labor Supplies and Labor) Solarization ” pump $25 / day $18.75 / acre $18.75 / acre It is assumed that 1.5 acres could be covered in a day.

6 mil clear $40 / 1,000m2 $160 / acre $160 / acre plastic

1,000 staples $60 / 1,000 $1,000 / acre $1,000 / acre

Labor to spread $90 / day $60 / acre $60 / acre and secure plastic and water site ( 2 people)

Total Estimated Cost per Acre $2,190 / acre

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4.3.1.2 Bassia hyssopifolia (fivehorn bassia) Bassia hyssopifolia, or fivehorn bassia, is an opportunistic species that will readily infest disturbed areas. Fivehorn bassia currently dominates 193.7 acres within the Upper Carson Slough and 55.7 acres within the Crystal Spring Management Units according to the vegetation map of the AHME (Bio-West 2010). Some of the larger infestations are in the vicinity of the Crystal Spring Channel alignment. The literature on this species is limited and little work appears to have been done in regards to its management. The following recommended treatment options for sparse and dense stands of fivehorn bassia are summarized as a per acre cost in Table 4.3 and Table 4.4.

Hoeing is recommended within small infestations to cut off weeds without penetrating too deeply into the ground, therefore preventing damage to the roots of desirable vegetation. Hoeing pockets of fivehorn within an extensive patch and replacing the weed with desirable native species should facilitate the re-establishment of native plant communities. A related approach has been to hand weed small areas of an infestation in sequence from the most intact stands of native vegetation to the most weed-infested stands of native vegetation. This approach will allow for a progressing front of native species establishment as fivehorn bassia decreases in abundance.

The California Invasive Plant Council does not recommend mowing or grazing as control methods for Bassia hyssopifolia (California Invasive Plants Database accessed 2011). However, mowing Bassia scoparia, a related species, has been highly effective if timed when the plant goes into fruit but before maturation of seeds. Given that both plants are annuals, if fivehorn bassia is mowed immediately before seed set, it will likely not be capable of resprouting after treatment. A combination of hoeing and mowing is recommended as a trial treatment of this species. Hand pulling, although effective for small infestations, is likely to be cost prohibitive throughout most of the AHME given the extent of invaded sites.

The use of herbicide is not recommended as this species readily develops herbicide resistant biotypes. However, if the managers want to test an herbicide, Vista® XRT has shown success in some Bassia-control trials (Wilson accessed 11/29/2011). The label recommends 6-12 fl oz. / acre of Vista® XRT with the addition of methylated seed soil surfactant (i.e. MSO or ESO) at the rate of 1-2 quarts / acre. When treating larger plants, it is recommended to increase the rate of Vista 10 13-17 fl/ oz per acre or add 1-2 quarts per acre of 2,4-D with the 1-2 quarts per acre of methylated seed oil to improve control.

Managers should expect to see an increase in Bassia hyssopifolia after fire if a seed source is nearby. In the Amargosa River Valley it has been shown to spread into saltgrass/mesquite areas recently disturbed by fire, although its persistence is unknown (California Invasive Plants Database accessed 2011). The Bassia hyssopifolia Herbaceous Alliance should be replaced with Distichlis spicata sod blocks. Burying the seedbank of this non-native species with sod after repeated mowing may inhibit Bassia regeneration.

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Table 4.3. Per Acre Treatment Costs of Bassia hyssopifolia in dense infestations.

Action Equipment , Cost Cost per Total Cost Notes Supplies, (of Equipment, acre per to Eradicate and Labor Supplies and year Labor) Mowing Labor $400 / day $80 / acre $160 / acre Mowing should occur twice a year if infestations are dense and be timed Tractor $225 / day $45 / acre $90 / acre to occur just prior to seed set.

Brush-hog $95 / day $19 / acre $38 / acre It is assumed that 5 acres can be mowed in a day. Burying Labor $400 / day $400 / $400 / acre It is assumed that sod will be with Sod acre salvaged onsite and that 1 acre can Tractor $165 / day $165 / acre be buried in a day. $165 / acre

Total Estimated Cost per Acre $128 / acre Burying with sod is only recommended for continuous patches of dense infestations and so it is not included in the total budget here.

Table 4.4. Per Acre Treatment Costs of Bassia hyssopifolia in sparse infestations.

Action Equipment , Cost Cost per Total Cost Notes Supplies, (of Equipment, acre per to and Labor Supplies and year Eradicate Labor)

Mowing Labor and $400 / day $25 / acre $50 / acre Mowing should occur twice a year if gas infestations are dense and be timed (1 person) to occur just prior to seed set.

Brush cutter $1,785 / It is assumed that 2 acres can be (with metal person* mowed in a day. blade) Total Estimated Cost per Acre $50 / acre *Under mowing, 1,785 is a fixed cost per person per brush cutter that should be included in the grand total but is not included here.

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4.3.1.3 Cardaria draba (hoary cress) Cardaria draba, or hoary cress, does not dominate any of the vegetation alliances found within the AHME. However, the California Invasive Plant Council rates this plant as a moderate threat to native plant communities. This species thrives in disturbed habitats where soil moisture is at or near the surface for some part of the growing season, and it will exclude native species.

Prescribed burning is not recommended, as hoary cress rootstalks will survive and take advantage of reduced competition following fire. Mechanical removal such as tillage should be executed with caution as even small fragments of roots will resprout. Tillage is recommended for infestations where treatments can be repeated within ten days of plant emergence. The goal is to prevent green leaves from developing so that the plant will expend its energy reserves.

Although mechanical removal is recommended over herbicide application, the herbicide 2,4-D may be used with a backsprayer application rate of 1.1kg ae/ha or glyphosate at 1 pt/acre. Aquatic versions of both 2,4-D (Aquakleen®, Navigate®) and glyphosate (Aquamaster®, AquaPro®) are registered for use near water. Either herbicide should be used in combination with a weed-whacker on flowering plants. Planting treatment areas with perennial grasses will stress hoary cress through competition. It is expected that weed-whacking and herbicide will need to occur several times throughout the growing season for several years to extirpate hoary cress from a site. This combination of treatments should be used on sites with a strong native plant component so that hoary cress can be eradicated without the need to do active revegetation. Sites without a strong native plant component may be more effectively treated with tillage as discussed above.

4.3.1.4 Centaurea melitensis (Malta starthistle) Centaurea melitensis, or Malta starthistle, does not dominate any of the vegetation alliances found within the AHME. The California Invasive Plant Council identifies this species as a moderate threat to native plant communities. Starthistle monopolizes soil moisture such that native plants in dense starthistle infestations will experience drought conditions even under normal precipitation; therefore, treatment is recommended if stands are likely to become dense.

Although the literature on Malta starthistle treatment is limited, grazing and mowing are not advised as these treatments may change the plant into a prostrate form that will produce more flowers and seeds. The California Invasive Plant Species Council recommends that treatments effective for yellow starthistle (Centaurea solstitialis) should be considered for Malta starthistle.

4.3.1.5 Centaurea solstitialis (yellow starthistle) Prescribed burning is effective at reducing cover and seedbank of yellow starthistle and increasing the abundance of native plants (Di’Tomaso et al. 999). Burning should occur prior to seed set of yellow starthistle. At this point in the season, herbaceous vegetation will have set seed and desiccated, providing the fuel necessary to kill yellow starthistle before its seed

38 Otis Bay Ecological Consultants matures. Burning will also give perennial grasses a competitive advantage as they will be capable of resprouting after fire. An infested site should burn for two or more consecutive years to sufficiently deplete the seedbank of yellow starthistle (University of California Agriculture and Natural Resources 2007).

Following treatment, sites should be actively revegetated. However, burning may increase yellow starthistle germination the following year, which will be stressful to planted species. If this happens, yellow starthistle seedlings should be treated with herbicide to give establishing native vegetation a competitive advantage. Treatments such as prescribed burning or use of broad-leaved specific herbicides such as 2,4-D will be more effective with native perennial grass species established onsite.

Aminopyralid and clopyralid are effective on yellow starthistle for both pre- and post- emergence treatments (University of California Agriculture and Natural Resources 2007). Aminopyralid should be applied between the months of December and March before plants have bolted. As clopyralid will not last as long in the soil, it should be applied between January and March. Earlier applications will not coincide with plant germination and later applications will require additional herbicide to be effective. Aminopyralid can be used at 0.75 to 1.75 oz ae/acre and clopyralid can be used 2 to 3.96 oz ae/acre. Aminopyralid is recommended as the safer option because it can be used up to the water’s edge, and the trademark aminopyralid herbicide, Milestone,™ has been declared a low-risk pesticide by the EPA .

Continued spot treatment of yellow starthistle will be necessary after the completion of site treatments. Either spot spraying or hand-pulling can be effective. The best timing for manual removal is after plants have bolted but before they produce viable seed (i.e., early flowering). At this time, plants are easy to recognize and some or most of the lower leaves have senesced.

If prescribed burning is not feasible, mowing could be substituted as long as buds and leaves do not remain on the stems following treatment. If buds and leaves are left on the stems, the plants will survive and the treatment will not be effective (University of California Agriculture and Natural Resources 2007). A single mowing of plants with an erect, high-branching growth, at the early flowering stage can effectively control plants. Repeated mowing will not be able to control sprawling, low-branching plants even with proper timing because buds and leaves will remain on the stems after treatment. Mowing is most effective when 2-5% of the seed heads have started to flower.

4.3.1.6 Cynodon dactylon (bermudagrass) Cynodon dactylon, or bermudagrass, currently dominates 154.6 acres of the Crystal Management Unit. This species is not mapped within the Upper Carson Slough Management Unit in the vegetation map of the AHME (Bio-West 2010), although it has been seen within the Management Unit and specifically along the Rogers Spring outflow. This weed is recognized by the California Invasive Plant Council as having a moderate level of negative ecological impact in California. Although this species is not of the highest concern, it is a threat to native plant

Carson Slough and Crystal Spring Revegetation | Final Report 39 communities given that it can spread at a rate of 2 meters a month in the growing season, and it is highly drought tolerant. The largest infestation of bermudagrass is within the vicinity of the Kings Spring Channel alignment, although other infestations are noted in this document with their respective spring outflow channels. The following recommended treatment options for bermudagrass are summarized as a per acre cost in Table 4.5.

Research on the management of this species has been limited. Prescribed burning is not a treatment option, as plant rhizomes will survive even severe fire. In its native Africa, the species regularly experiences fire (Belesky et al. 1991). Bermudagrass is shade intolerant and will die under moderate to dense shade conditions. Bermudagrass is an early successional species and is favored by disturbances such as grazing. As natural plant succession proceeds in some of the invaded areas, a passive decline in the cover of bermudagrass may occur.

Because the literature is mixed on treatment recommendations for bermudagrass and there is no assured method of control, experimentation with a variety of treatments is recommended. Work in Botswana combined tillage with a summer application of glyphosate and resulted in reduced cover and biomass of the grass (Abdullahi 2002). Tilled rhizomes will resprout given appropriate soil moisture, thus invaded sites should be tilled in late spring once soil moisture is depleted to stress the plants as much as possible.

Glyphosate is a non-selective herbicide and will kill most plants with which it comes into contact. If pockets of bermudagrass can be controlled with glyphosate and replaced with desirable species such as mesquite, the increase in shade will give native plants a competitive advantage within treated patches. Timing of glyphosate application is crucial for its control. Glyphosate should be applied to bermudagrass that is actively growing and is not stressed by drought, insects or mowing (Cudney et al. 2007). Therefore, application at AHME may need to occur in the spring. After seven days, the treated area should be cultivated to bring rhizomes and roots to the surface to ensure that no parts of the plants survive.

Solarization may also be an effective treatment of bermudagrass (Elmore et al. 1993). Solarization could be done in patches large enough to plant desirable species. In monocultures of bermudagrass, desirable native plants could be planted into these solarization treatment patches. Once established, native species are likely to shade out the weed and result in additional control. Solarization requires that the grass be mowed close to the ground, clippings removed, and the area watered well before being covered with four mm thick plastic sheets. Plastic should extend two feet beyond the above ground infestation to ensure that roots and the soil seedbank are also treated. The edges of the plastic should be stapled and covered with soil to secure the sheet. The plastic sheet should remain intact (without holes) for 4-6 weeks. The treated area should not be cultivated to avoid moving surviving seeds to the surface where they can develop new plants. Solarization treatment following herbicide is likely to be more cost effective than tilling unless a large, continuous area is being treated (Elmore et al. 1993).

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Table 4.5. Per Acre Treatment Costs of Cynodon dactylon.

Action Equipment , Cost Cost per acre Total Cost Notes Supplies, and (of Equipment, per year to eradicate Labor Supplies and Labor) Herbicide Aqua Neat $33 / gal $12.40 / acre $24.80 / acre It is assumed that each acre will be treated twice with Application (glyphosate) herbicide and once with solarization. Follow-up treatments will be necessary after three years, but with Liberate w/ leci $30 / gal $3.75 / acre $ 7.50 / acre reduced weed cover, the costs of each subsequent year tech (Non-ionic should be far less than the previous year. surfactant) Plants should be sprayed to wet. We have assumed an Turf Trax $32 / gal $6.25 / acre $12.5 / acre application volume 25 gallons per acre of 1.5% solution (blue dye) (1.5 qt herbicide per 25 gal water).

Certified Applicator $760 / day $380 / acre $760 / acre Surfactant addition has been calculated at 0.5 qt per 25 gal of spray.

1 oz of dye should be used per gallon of spray.

It is assumed that 2 acres a day can be covered with a broadcast sprayer. Mowing Labor and gas $400 / day $200 / acre $400 / acre Mowing grass close to the ground will ensure that high (1 person) temperatures are reached at the soil surface.

Brush cutter (with $1,785 / It is assumed that 2 acres can be mowed in a day. metal blade) person* The $1,785 per person is the estimated cost of buying one brush cutter for one person.

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Table 4.5. Per Acre Treatment Costs of Cynodon dactylon. (continued)

Action Equipment , Cost Cost per acre Total Cost Notes Supplies, and (of Equipment, per year to eradicate Labor Supplies and Labor) Solarization ” pump $25 / day $18.75 / acre $37.50 / acre It is assumed that 1.5 acres could be covered in a day.

4 mil clear plastic $40 / 1,000m2 $160 / acre $160 / acre Not all sites will need to be watered before the plastic is applied.

1,000 staples $60 / 1,000 $60 / acre $60 / acre It is estimated that 1,000 staples will be needed to secure staples plastic sheets over 1 acre.

Labor to spread $800 / day $540 / acre $540 / acre Solarization as opposed to mowing is included here and secure plastic because it is thought to be more cost effective. and water site ( 2 people) Total Estimated Cost per Acre $2,000 / acre *Under mowing, $1,785 is a fixed cost per person per brush cutter that should be included in the grand total but is not included here.

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4.3.1.7 Elaeagnus angustifolia (Russian olive) The California Invasive Species Council rates Elaeagnus angustifolia, or Russian olive, as posing a moderate threat to native plant communities. It currently occurs on approximately 20 acres of the AHME, where it is found primarily on homestead sites and along roadways. While its range does not appear to be rapidly e panding, Russian olive’s ability to dominate native plant communities paired with the relatively small area of current distribution makes it a worthwhile target for management efforts (US Fish and Wildlife Service 2006a).

The Bio-West 2010 vegetation map of AHME shows two primary areas of concentration, one within the Upper Carson Slough and the other to the southeast of lower Crystal Reservoir, as well as moderate dispersal in between. While treatment and removal is recommended for areas of active restoration, it may be beneficial to postpone treatment in other areas until restoration is underway. Russian olive is considered detrimental in its ability to alter native stand structure and nutrient cycling (Tu 2003), but it has been shown to provide habitat for wildlife (Knopf and Olson 1984). A number of birds observed in the Knopf and Olson study are frequenters of Ash Meadows, and the southwestern willow flycatcher will nest in Russian olive if native vegetation is unavailable (USFWS 2002). Given that Russian olive provides some benefit for wildlife, it may be worthwhile to leave stands outside active restoration areas until a more comprehensive plan could ensure the succession of beneficial species.

Recommended treatment options include mechanical removal and/or herbicide application. Saplings and sprouts may be removed by weed wrenching and hand pulling, with focus on removing root mass; this method is beneficial in that it causes little disturbance but may be costly in labor expense. Saplings less than 2.5 cm diameter may be effectively mowed. Mowing is quick but must be repeated regularly to prevent saplings from growing larger than 2.5 cm diameter, at which point mowing may encourage root sprouting (Shafroth et al. 2010). Mechanical removal of larger trees is possible if restoration of the site allows for excavation and large-scale soil disturbance but is otherwise costly and impractical given the necessity of removing significant root mass to prevent resprouting.

Herbicide application is the primary recommendation, effective for both young and older trees. Studies have shown a high degree of success using the “cut-stump” method, in which trees are first cut as close to the ground as possible and then the remaining stumps sprayed with Glyphosate (e.g. RoundUp®), triclopyr (e.g. Garlon 4®) or some combination of the two (Shafroth et al. 2010). To be most effective, (1) stumps must be sprayed within five minutes of being cut, (2) all stumps (including lower braches) must be thoroughly wetted, (3) spray must cover the vascular cambium, and (4) herbicide must penetrate the stump. Other effective methods of herbicide application include the “hack and squirt” method, in which trees are cut to the phloem and then herbicide is applied into the cut, and basal bark application, in which the bottom 15 inches of trees are sprayed with triclopyr or imazapyr (Shafroth et al. 2010).

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4.3.1.8 Phragmites australis (common reed) Phragmites australis, or common reed, is a native plant but may be considered a “cryptic invader” because at least one non-native genotype has been introduced from Eurasia (Saltonsall 2002). This non-native genotype may allow common reed to spread prolifically through landscapes. Genetic tests are needed to discern if the common reed in AHME is a non- native genotype. Common reed currently dominates 131.4 acres within the Upper Carson Slough and 113.6 acres within the Crystal Spring Management Units according to the vegetation map of the AHME (Bio-West 2010). The following recommended treatment options, with the exception of prescribed burning, are summarized as a per acre cost in Table 4.6.

Prescribed burning may be effective in late summer and especially after herbicide treatments, but winter and spring burning may increase densities of spring crops. However, if properly timed, burning in the emergence period can lead to death of the majority of shoots (van der Toorn and Mook 1982). If possible, an attempt to temporarily dry out sites next to standing water will increase the sites’ ability to burn.

One study examining the combined effects of herbicide (glyphosate) and burning treatments observed that Phragmites not killed in treatment had expanded after three years. Although higher plant diversity was observed in the herbicide-only treatment at the end of the study, burning did favor the rapid re-establishment of non-target vegetation (Ailstock et al. 2001). The combination of herbicide and prescribed burning treatments will likely result in the restoration of full vegetative cover.

Phragmites seed only survives on bare soil (Ailstock et al. 2001). Therefore the removal of vegetation cover, as would be expected with channel reconstruction, could favor the establishment of this weed from seed as seen in the recent Fairbanks Spring restoration. Revegetation efforts immediately following construction will minimize this threat.

Rhizomes of common reed lie within the upper 6-8 inches of the soil profile. Repeated tillage will kill top growth and eventually exhaust below ground energy reserves if performed in two- week intervals. Equipment must be thoroughly cleaned before leaving a tilled common reed site to avoid introducing this weed to new locations.

The Michigan Department of Environmental Quality (2008) compiled the field experiences of several land managers who have worked towards control of common reed. The resulting guide book recommends a combination of treatments to effectively control well-established stands. They specifically recommend an initial treatment with herbicide followed by prescribed fire or mechanical treatment and water level management. The authors believe that imazapyr may be more effective on common reed than glyphosate or a mixture of the two herbicides. However, given inconsistency in the literature, trying different herbicide combinations would be worthwhile.

Imazapyr should be applied during the active growing season after full leaf elongation, and glyphosate should be applied later in the year, when plants are in full bloom, from the late 44 Otis Bay Ecological Consultants summer up to the first killing frost. Plants will die within 6-8 weeks, at which time dead Phragmites should be mowed in order to promote native plant establishment. Prescribed fire should be conducted in the year following herbicide treatment, preferably in late summer or, less ideally, from January until prior to spring green-up. If prescribed fire cannot be conducted then mechanical treatment is an option. Using prescribed fire or mechanical treatment to remove Phragmites biomass will make resprouts easier to identify and treat. Mechanical treatment should occur at least two weeks after herbicide treatment to allow for plant absorption of the herbicide. The resulting thatch should be bagged and disposed of to prevent seed spread and allow sunlight to reach the soil surface. The site should be checked the following growing season for Phragmites growth and spot-treated with herbicide as needed. Treatment of resprouts should be minimal at the end of two years.

Common reed seedlings are very sensitive to competition, so replanting treated areas with native species will be an important part of controlling this weed. Recommended species for replanting vary greatly because Phragmites can invade many habitats, including saturated, semi-permanently, seasonally and temporarily flooded wetlands as well as upland areas. Planting recommendations are therefore given on a channel-by-channel basis.

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Table 4.6. Per Acre Costs of Phragmites australis Treatment.

Action Equipment, Cost Cost per acre Total Cost Notes Supplies, per year to eradicate and Labor

Herbicide Habitat $160 / gal $120 / acre $240 / acre Each acre should be treated twice with herbicide and mowed or burned once. Application Follow-up treatments will be necessary after three years, but with reduced weed Aqua Neat $33 / gal $12.40 / acre $24.80 / acre cover, the costs of each subsequent year should be less than the previous year.

Liberate w/ $30 / gal $7.50 / acre $15 / acre Habitat (imazapyr) should be applied at 6 pints/ acre. The application volume was leci tech calculated at 25 gallons / acre, resulting in 2.5% solution / acre. (Non-ionic We assumed an Aqua Neat (glyphosate) application volume of 25 gallons / acre of surfactant) 1.5% solution (1.5 qt herbicide / 25 gal water).

Turf Trax Surfactant addition was calculated at 0.5 qt / 25 gal of spray for each herbicide. (blue dye) $32 / gal $12.50 / acre $25 / acre It is assumed that 2 acres a day can be treated with a backpack sprayer. Habitat and Certified $760 / day $380 / acre $760 / acre Aqua Neat should be applied simultaneously (in the same mix) to maximize uptake Applicator by each plant and minimize application costs. Mowing Labor & gas $400 / day $80 / acre $160 / acre It is assumed that 5 acres can be mowed in a day. (High (1 person) Density) Phragmites should be mowed after herbicide treatments, once a year for two years. Tractor $225 / day $45 / acre $90 / acre Depending on the density of resprouts, it may be more economical to mow resprouts with a brush cutter. Brush-hog $95 / day $19 / acre $38 / acre High density mowing is estimated to cost a total of $288 / acre. Mowing Labor & gas $400 / day $200 / acre $400 / acre It is assumed that 2 acres can be mowed in a day. (Low (1 person) Density) Phragmites should be mowed after herbicide treatments, once a year for two years. Brush cutter $1,785 / The $1785 / person is the estimated cost of buying one brush cutter for one person. (with metal person* blade) Total Estimated Cost per Acre $1,353/ acre *Under mowing, $1,785 is a fixed cost per person per brush cutter that should be (high density) included in the grand total but is not included here.

$1,465/ acre (low density)

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4.3.1.9 Sisymbrium irio (London rocket) This non-native mustard has been rated as a moderate threat to native plant communities by the California Invasive Plant Council, although the impacts of the weed are thought to vary locally. This plant matures earlier in the year than native plants, allowing it to outcompete them. After the El Nino rains of early 2010 there was an increase in cover of this species, which was treated with glyphosate (Carl Lundblad, pers.comm.). The long-term effects of this treatment are unknown. London rocket does not need to be considered for treatment at this point in time, but. AHME staff should continue to monitor this plant. If populations increase and threaten native plant communities, mowing individuals before seed set would be an appropriate treatment of this annual species.

4.3.1.10 Solanum elaeagnifolium (silverleaf nightshade or ground cherry) Silverleaf nightshade is listed as a Category “B” weed on the Nevada Noxious Weed List (Nevada Dept. of Agriculture accessed November 17, 2011). Currently, this plant does not dominate any of the vegetation alliances mapped throughout the AHME (Bio-West 2010). The plant can be hand pulled or mowed, preferably before seed-set, with an emphasis placed upon removing the roots from the soil. It can also be treated with glyphosate, although most of the other weeds listed here are of higher priority. Silverleaf nightshade should be made a higher priority for treatment if individuals begin spreading rapidly and crowding out native plants.

4.3.1.11 Sorghum halepense (Johnsongrass) Sorghum halepense, or Johnsongrass, does not dominate any of the vegetation alliances found within the AHME, but the U.C. Integrated Pest Management Program looks upon this species as being “one of the most troublesome of perennial grasses.” This highly aggressive grass reproduces from rhizomes and seeds.

Mowing the grass for several seasons weakens plants and reduces rhizome growth. Mowing in the spring during initial above-ground growth and in the fall during the over-wintering rhizome formation will stress plants when their energy reserves are low. Smaller infestations can be effectively treated with hand hoeing, especially early in the season when plants are young.

If mowing or hand hoeing is not a practical treatment option, glyphosate can be used. Herbicide application is most effective when plants are actively growing, greater than 18 inches tall, blooming and beginning to form seed. Treatment sites should not be disturbed for at least a week after application to ensure that treated plants take up as much herbicide as possible. Multiple applications for several years will be required.

4.3.1.12 Tamarix species (saltcedar) Tamarix ramosissima and Tamarix aphylla dominated 249.3 acres within the Upper Carson Slough and 38.4 acres within the Crystal Spring Management Units (Bio-West 2010). This phreatophyte forms dense stands and produces large quantities of leaf litter, crowding out native plants. Tamarisk establishes and thrives not only in riparian areas but also on the upper terraces where the water table is too deep for establishment of willow and cottonwood. Sites

Carson Slough and Crystal Spring Revegetation | Final Report 47 with high tamarisk cover often experience a change in hydrology, resulting in site conditions that no longer facilitate establishment of riparian species. Removal of tamarisk is particularly challenging as residual roots will resprout and establish new plants, and healthy individuals will resprout following fire. The majority of tamarisk in the Upper Carson Slough and Crystal Springs Management Units have recently been extracted or treated with herbicide, but resprouts will likely need treating in the near future (C. Baldino, pers. comm.).

The ability of tamarisk to resprout is reduced when root crowns are excavated. The mechanical removal of the root crown and all lateral roots is crucial for killing mature tamarisk. Excavation of tamarisk individuals within the construction footprint should occur, if possible, during channel construction. Although root fragments left behind will resprout, these resprouts will have less root mass and therefore reduced viability. Individuals with excavated root crowns can be treated with foliar spraying or stem cutting and follow-up herbicide applications consisting of a mixture of the aquatic versions of imazapyr (Habitat®) and triclopyr-TEA (Garlon 3A).

Foliar spray may be preferable to cutting the stems because this method allows for the transport of more herbicide into the root. Cut stems must be treated within a minute of cutting to absorb into the plant. Plants should not be disturbed for a year; therefore if the weed treatment area overlaps with a revegetation area, plants should not be treated until efforts are underway. Care should be taken to spray herbicide only near tamarisk to avoid drift. Irrigated areas containing tamarisk should be treated when plants are dry and irrigation can be turned off for 24 hours to allow herbicide to absorb into the plants.

Lone tamarisk are often surrounded by desirable vegetation and therefore should not require active revegetation as long as the native plants persist. In such situations, where use of an excavator might damage the native vegetation, the “cut-stump method” is recommended. This involves cutting tamarisk stems to within 5 cm of the soil surface and then thoroughly wetting them with an herbicide, such as triclopyr (e.g. Garlon4®), within one minute of cutting.

SWEAT, LLC chemically and mechanically treated tamarisk throughout AHME. The Meadows fire, which burned between July 29 and August 1, 2005, favored the growth of tamarisk over native plants as tamarisk readily resprouts following fire. The burn perimeter overlaped with 95% of the Jackrabbit Spring Channel and encompassed 311 acres (USFWS 2006b). Within the perimeter of the Meadows fire, saltcedar was extracted using a low ground pressure (4.5 to 6 pounds per inch2) excavator with a “thumb” attachment. E tracted individuals were chipped using a Hydro-axe 421E or 721E with a Fecon head attachment, resulting in chips ranging from 2 to 6 inches. If treated areas receive active revegetation, using wood chips as mulch will facilitate plant establishment by increasing soil moisture retention.

Given that the tamarisk within the vicinity of proposed channel alignments were resprouting individuals, we recommend spot treatment with herbicide. Areas of dense tamarisk, including those requiring excavation, should be replanted with a mixture of Distichilis spicata, Muhlenbergia asperifolia, Sporobolus airoides, Atriplex canescens and Atriplex confterifolia. These species are good competitors that do well under stressful conditions. 48 Otis Bay Ecological Consultants

Table 4.7. Per Acre Costs of Tamarix spp. Treatment.

Action Equipment , Cost Cost per acre Total Cost Notes Supplies, and (of Equipment, per year to eradicate Labor Supplies and Labor) Herbicide Habitat® $160 / gal $120 / acre $240 / acre Tamarisk individuals that were encountered in the vicinity of Application the restored channel alignments were resprouts and do not Garlon 3A $85 / gal $42.50 / acre $85/ acre necessitate the use of an excavator.

Liberate w/ $30 / gal $3.75 / acre $7.50 / acre It is assumed tamarisk will be treated twice with herbicide. leci tech Although many of the individuals encountered were (Non-ionic resprouts, it is unclear if they have already been treated surfactant) twice. Two additional treatments should result in the mortality of these individuals. Turf Trax $32 / gal $12.50 / acre $25 / acre (blue dye) Plants should be sprayed to wet.

Certified $760 / day $380 / acre $760 / acre Habitat (imazapyr) should be applied at 3 qt per acre. The Applicator application spray volume has been calculated at 25 gallons per acre, which results in a 2.5% solution per acre. We have assumed a Garlon 3A (triclopyr) application volume of 25 gallons per acre of 2% solution (2 qt herbicide per 25 gal water).

Surfactant addition has been calculated at 0.5 qt per 25 gal of spray.

It is assumed that 2 acres a day can be covered with a backpack sprayer. It is recommended that Habitat and Garlon 3A be applied simultaneously to maximize uptake by each plant and to maximize application costs. Total Estimated Cost per Acre $1,118 / acre Given the high number of tamarisk resprouts, this per acre costs is estimated as being equivalent to treating 50 individuals.

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4.3.1.13 Tribulus terrestris (puncturevine) At this time, the California Invasive Plant Council does not list Tribulus terrestris as a threat to native plant communities and this species does not dominate any of the vegetation alliances mapped throughout the AHME (Bio-West 2010). Small infestations are best controlled with manual removal. Using a hoe to cut off the plant at the taproot or mowing is not recommended because the plant is prostrate. Treatment with glyphosate or pulling, digging or tilling prior to flower and seed production is effective. Following treatment, the site should be monitored for 5 years because of seedbank longevity. Seeds may remain viable for 3-7 years. Planting competitive species such as perennial grasses within treatment areas will decrease the likelihood of reinvasion. Treatment of puncturevine should be made a higher priority if individuals begin spreading rapidly and crowding out native plants.

4.3.1.14 Typha species (cattail) Typha spp. currently dominate 290.4 acres within the Upper Carson Slough and 139.6 acres within the Crystal Spring Management Units according to the vegetation map (Bio- West 2010). Although native, there is evidence that the range of cattails is expanding over time, and the overabundance of Typha constricts stream channels and fills open water habitats needed for several of the aquatic fauna present within the AHME. Cattail species favor disturbance, and simple changes to hydrology allow the plants to invade other plant communities (http://plants.usda.gov/java/charProfile?symbol=TYLA accessed August 17, 2011). Typha glauca is the hybrid of Typha angustifolia or domingensis and latifolia, and hybrids often benefit from the genetic phenomenon known as hybrid vigor. Although the species has not been documented in Nevada, it has been documented in California, Oregon, and Utah. AHME staff should be aware that this hybrid is highly aggressive and will outcompete other Typha species.

Cattails can be difficult to eradicate from a site. Flooding does not always have a negative impact as plants can float up with rising water levels. It has been suggested that draining a wetland and burning it during the summer may be effective although this may also eliminate desirable species. Crushing cattails with a water-filled drum pulled behind a tractor, although effective, is also likely to harm desirable native plants.

The AHME has obtained favorable results controlling cattails both by spraying the herbicide Habitat® (an aquatic formulation of imazapyr) along the banks of springs and streams, and by cutting cattails and then submerging them with more than 3 inches of water. Cutting in the late summer or early fall is recommended to create the greatest amount of stress on energy reserves of the plant. Cutting these plants too early in the season will stimulate growth and cutting too late in the season, such as after the flowering stage, will have no effect on growth in the subsequent year (Malik and Wein 1986).

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Dominance of stream channels by cattails can be reduced by constructing narrow and deep stream channels designed and sized according to the amount of spring discharge and slope of the landscape. Where the slope is very low, it may not be possible to prevent colonization by cattail without a substantial commitment to revegetation and the establishment of more desirable species.

In areas likely to exhibit shallow, spreading water, a mixture of Eleocharis, Schoenoplectus, Juncus, and Carex should be planted immediately following construction. We recommend planting species that are components of the Schoenoplectus americanus Semipermanently Flooded Herbaceous Alliance in areas formerly occupied by cattails because Schoenoplectus is particularly adept at competing with cattails (Thomas et al. 2004). The removal of hydrologic barriers from AHME will likely decrease the area of shallow, spreading water and will therefore aid a reduction of this species. A shift back to what are believed to be the historically more prevalent bulrush-dominated communities should be focused on sites with flowing water, where abiotic conditions are less likely to favor the establishment of Typha spp than sites with ponding water.

4.3.2 Coordination of Weed Removal Efforts SWEAT, LLC and Conservations Services, LLC have treated a number of areas throughout the AHME for the following weeds: Acroptilon repens (Russian knapweed), Bassia hyssopifolia (fivehorn bassia), Bromus rubens (red brome), Cardaria draba (hoary cress), Centaurea melensis (Malta starthistle), Convolvulus arvensis (field bindweed), Elaeagnus angustifolia (Russian olive), Sisymbrium irio (London rocket), Solanum elaeagnifolium (silverleaf nightshade), Sorghum halepense (Johnsongrass), Tamarix spp. (saltcedar), and Washingtonia filifera (California fan palm). Future weed treatment efforts should include monitoring of treated sites and follow-up treatments.

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4.3.3 Additional Weed Concerns Water table elevation will change within select portions of the Upper Carson Slough Management Unit following hydrologic restoration. New channels will re-route water through areas that are not currently mesic and, as water infiltrates into areas adjacent to the channel, new wetlands will be created. In the nearer future, this is will result in the addition of 415 acres of marsh (see Section 11). According to the Bio-West (2010) vegetation map, this new marsh area will encompass 82 acres of common reed, 141 acres of saltcedar and 96 acres of cattails based upon the vegetation map ). Within the Crystal Spring Management Unit, construction efforts will result in the addition of 222 acres of marsh. The new marshlands within the Crystal Spring Management Unit will encompass 3.85 acres of common reed and 6.2 acres of saltcedar.

Existing patches of these weeds that fall within the expected sites of new marshlands should be treated immediately. If left untreated, these species will expand into the increased acreages of marsh. As of 2012, the majority of tamarisk in this area has been treated, but resprouts will need to be monitored. Treatment of tamarisk in newly- formed marshes will depend upon the degree of saturation. Tamarisk cannot survive in submerged conditions, so it is likely that some will die. Individuals present in marshes should be monitored. Saturated soils will eliminate the option of removing tamarisk with heavy equipment. Surviving tamarisk will have to be treated individually with the cut stump or foliar spray methods discussed previously.

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4.4 Preparation of the Soil Surface Following the completion of all stream channel construction activities, the construction footprint should be ripped to ensure that soils are not compacted. Ripping will allow for increased water infiltration rates which will aid in plant establishment. Any additional soil amendments should be based upon soil tests. Most of the steam channel areas will not require soil amendments because they currently support healthy plant communities. However, we recommend other soil amendment techniques for abandoned agricultural fields (See Section 8.1)

Excavated soils from channel construction can be spread over the construction footprint to create nutrient-rich and weed-free revegetation surfaces. As soils are excavated and spread, the first 6- ” should be kept separate from soils found deeper than ”. The shallower soil layers are likely to have a greater abundance of plant propagules including both seed and rhizomes. If the soil surface has an abundance of undesirable plants prior to excavation, it should be set to the side and solarized. Solarization should happen in summer or at least when ambient temperatures are high. Soils should be cleared of weeds, well watered and covered with 2 mm thick clear plastic. The edges of the plastic sheet should be secured and the plastic kept in place for a minimum of four weeks. At this point, the soil should be turned to a depth of 18 inches to bring any weed seed to the surface. The soil should then be watered deeply and the plastic replaced for another four weeks. After the second four weeks, untreated donor soils that are truly weed free can be mixed with the solarized soil to reintroduce soil microbes. These soils can then be used in planting efforts.

Nutrients and organic matter are often limited in areas of new top soil, so hay and straw mulch are commonly used to increase organic matter in the soil. Care should be taken to use only certified weed-free straw. Between 0.5 and 1 ton per acre can be spread over the area depending on wind conditions. Straw should be crimped in by a straw crimper or by running an excavator bucket over the soil surface of applied straw to help hold the straw in place. However, it should be anticipated that some straw will be lost in windy areas. New microtopography from soil crimping will create favorable sites with increased soil moisture, reduced salinity, reduced soil compaction, increased water absorption and decreased evaporation.

The Integrated Pest Management Plan for Ash Meadows National Wildlife Refuge (USFWS 2006a) advises against using fertilizers in revegetation projects in the Mojave because native plants in this system are adapted to the low nutrient levels often found in desert soils. As such, these species cannot quickly use these additional nutrients, whereas weedy species may. An increase in nutrient availability can lead to an increase in invasion by non-native plants (Davis et al. 2000), although keeping resource levels low may not always decrease the likelihood of weed establishment, depending on the species (Funk and Vitousek 2007). Keeping rates of fertilizer low in close proximity to the channel will also minimize the risk of altering stream ecology.

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However, low-level application of fertilizer can promote better plant establishment during the early growth stages when plants need additional nutrients. The use of fertilizer such as an N-P-K 16-16-16 will likely increase initial plant growth rates, but it must be used sparingly. Plants overly-encouraged with readily available nutrients and water may grow beyond what their root systems can support once irrigation is removed. The goal of fertilizer and irrigation in the Mojave is to establish an extensive root system that can support a plant under harsh site conditions.

4.5 Planting and Irrigation 4.5.1 Planting Seeding native species was considered in this revegetation plan. However, due to the need to quickly establish vegetation in order to prevent weed infestations and erosion, as well as the harsh conditions of the site, we recommend that revegetation efforts focus on planting salvaged and containerized individuals.

The area adjacent to each channel alignment has been divided into planting zones (Figure 3-3). Up to a meter from the water’s edge, individuals of wetland species such as Juncus arcticus ssp. littoralis and Carex praegracilis should be planted in patches about 10 ft or 3 m apart. The USDA Plant Materials Center has shown that the establishment of wetland transplants is increased when planted in patches. It is anticipated that soil moisture conditions will be appropriate for these species within a meter from the water’s edge but planting zones should be modified onsite to fit soil moisture conditions. If planted at 18 inches on center, 12 plants can be planted within a 10 ft length of the channel with bordering 10 ft lengths being left fallow.

After planting, care should be taken not to raise water levels more than 1 inch for approximately one week in order to minimize plant stress. Both Juncus arcticus ssp. littoralis and Carex praegracilis are rhizomatous and spread quickly once established. In unplanted and exposed areas, biodegradable erosion control fabric could be used in the year following planting to ensure that undesirable species do not establish prior to Juncus and Carex. Individuals of these species have been contract grown for the AHME in the past. If individuals are not available for these planting efforts, plant material salvage is a viable source.

In areas where the spread of wetland plants is a concern, as in open water habitat being created or maintained for endemic fish species, salvaged Scirpus spp. (now Schoenoplectus spp.) or Eleocharis spp. can be used. Three species of Schoenoplectus occur within the AHME: Schoenoplectus americanus, Schoenoplectus maritimus, and Schoenoplectus robustus. Schoenoplectus spp. are highly desirable along newly excavated channels because they do not encroach into the channel. Although both Eleocharis parishii and Eleocharis rostellata are found within the AHME, only Eleocharis rostellata has growth habits described by the USDA. This species exhibits the desired

54 Otis Bay Ecological Consultants characteristics of a plant where creation of native fish habitat is a priority: moderate rate of vegetative spread, grows in all soil textures, tolerant of low fertility soils, moderate salinity tolerance, and it can be propagated by bare root so that salvage plantings can be used. Schoenoplectus spp. will likely grow back into salvage source holes within a single growing season if no more than 4 dm2 is taken within a 1 m2 area.

In drier site conditions on the wetland fringe, grasses should replace rushes and sedges as the dominant planted species. A large portion of the construction footprint consists of Distichlis spicata Intermittently Flooded Herbaceous Alliance (47.8 acres). Sod can be salvaged from these sites. Salvaged Distichlis spicata sod should be kept moist after collection and can be stored for up to 28 days at temperature ranges from 35-50°F degrees. To minimize stress from transport and planting, sod should be planted at a depth of 1- ” as quickly as possible after collection. Rhizomes should be planted with growth nodes sticking upright. Seed from other desired grass species should be collected and grown out to mature, 1-gallon size individuals. Growing out collected seed to 1-gallon sized plants will increase the likelihood of survival under the harsh site conditions that are present throughout the AHME.

Recommended grass species include Aristida purpurea, Muhlenbergia asperifolia, Poa secunda, and Sporobolus airoides. A number of shrubs are recommended for use as well and should be grown out in #1-size containers. These include Atriplex canescens, Atriplex confertifolia, Atriplex lentiformis, Baccharis emoryi, Encelia actonii, Larrea tridentata, and Prosopis glandulosa. The tree Fraxinus velutina can be propagated from bare root, but because it is a highly desired species on the AHME, it is recommended that plants be grown out from seed to ” caliber individuals. This sized tree should be herbivory resistant and quickly provide a seed source for future recruitment of this species.

Transplanting should occur in the winter or early spring to reduce transplant shock. All transplants should be planted into supersaturated soil with the top of the root crown even with the soil surface. Grasses and forbs should be planted between 6 and ” above saturated soils. Shrubs and trees should be planted between 8 and 4” above saturated soils. Tree shelters should be placed around small woody plants and the plants should be supported with stakes 3/8” by 3’. In areas where herbivory by rodents is a concern, tree shelters should be used around trees and shrubs to prevent casualties.

High winds often lead to soil erosion in the Mojave. In areas where woody material is available, vertical mulch can be added within the revegetation site to act as windbreaks, reduce soil erosion, trap fine soil, and increase seed and organic matter.

4.5.2 Irrigation Irrigation is necessary to ensure successful revegetation efforts in arid landscapes; in most years, plants will not establish without supplemental water. However, irrigation is

Carson Slough and Crystal Spring Revegetation | Final Report 55 costly. If staff is available to run the irrigation system, a pump with a gas, diesel, or solar power engine can be used to extract water from the channel. A screen-covered intake should be used to ensure that no fish become entrained. The soil profile should be wetted to 4” and kept moist until plants are established.

Excessive water use can result in salt mobilization and soil crusting, causing damage to the soil structure and a build-up of soluble salts. In arid environments, an increase in water can also increase the invasibility of onsite vegetation (Harrington 1991). Invasion of Descurainia sophia and Sisymbrium spp. due to increased water availability can occur in the Great Basin and Mojave (L. Condon, pers.comm.). Therefore, water should be delivered directly to plantings, preferably via drip and / or deep pipe irrigation.

DriWater® is another option for irrigation. These containers are installed near the roots of plants and slowly release moisture over a two month period. In AHME these containers would need to be replaced at least a couple times per growing season. The labor expenses incurred with this method can be costly.

4.6 Monitoring and Further Weed Removal Efforts Monitoring of weed treatments and plantings should occur monthly for the first year and at least quarterly thereafter. In order to gather quality data, 5 to 10 permanent transects (oriented perpendicular to the spring channel in the case of channel restorations) should be established. Along these 50-meter transects, ten (10) 1m X 1m quadrats should be placed on alternating sides of the transect tape. Percent cover should be estimated ocularly by species, and the number of plants or approximate density should be recorded. Information gathered within these quadrats should also include presence/ abundance of herbivory. Additionally, permanent photo monitoring sites (1 photo each cardinal direction) should be established prior to restoration to document changes in plant diversity and plant community structure. These photo monitoring sites could be assigned to a certain point along the 50-m transects.

Frequent monitoring will allow for the detection of any potential problems such as weed invasions and plants receiving inappropriate amounts of water. This information can then be used to alter planting, irrigation and/or herbivory protection techniques as necessary. Monitoring will also elucidate ways to improve future revegetation efforts through the refinement of soil preparation techniques, species planting lists, etc.

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5 UPPER CARSON SLOUGH

Upper Carson Slough refers to the northern half of the AHME. Channel construction began within the Upper Carson Slough Management Unit in December of 2009 with the construction of the Fairbanks Channel. We estimate that channel construction will result in the rising of the water table over approximately 415 acres and that this rise will create stream channel and emergent marsh habitat (Figure 5-1). This rising of the water table is not included within the acreages of vegetation alliances proposed for planting within the construction footprint due to unaccounted factors that may change the extent of the potential emergent marsh habitat shown in Figure 5-1. Marshland vegetation is highly dependent upon soil moisture and should only be planted if the soils in the area are saturated. Following channel construction, any proposed vegetation types may be replaced with the proposed wetland vegetation type if the soils become saturated.

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Figure 5-1. Areas of potential marsh habitat within the Upper Carson Slough Management Unit (415 acres) calculated by Otis Bay, Inc.

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5.1 Weed Treatments within Upper Carson Slough Phragmites australis (common reed) and Tamarix spp. are abundant in the Upper Carson Slough (Figure 5-2). Tamarisk has been a primary focus of treatment efforts in AHME. A single tamarisk plant can produce 2.5 x 108 wind-dispersed seeds per year (Stevens 2010), and seedling densities have been observed to be as high as 16,000/m2 (Warren and Turner 1975). Therefore, any remaining individuals are a threat to native plants in the AHME. Thus, treatment and monitoring of tamarisk are of high priority.

With the expansion of emergent marsh habitat throughout the Upper Carson Slough, the threat of further invasion by tamarisk and common reed is high. Therefore, common reed treatment should be of high priority following channel restoration. Russian knapweed and bermudagrass are listed as a moderate threat by the California Invasive Plant Species Council. These species spread quickly and should be of high priority for treatment.

The other weeds of concern in Upper Carson Slough are ruderal species that favor disturbance. Treatment efforts and active revegetation will expedite the restoration of native species to disturbed sites. Weed treatments should prioritize control of small, manageable infestations first and then contain and eradicate larger infestations (Moody and Mack 1988).

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Figure 5-2. Map of weed dominated vegetation alliances within the Upper Carson Slough from the BioWest vegetation map (2010). 60 Otis Bay Ecological Consultants

5.2 Fairbanks Spring Channel The first priority in revegetation efforts for the Fairbanks Channel should be to plant salvage material of wetland species within the construction footprint Common reed, tamarisk, and cattails are all invasive species of concern within proximity to the Fairbanks Channel that have the potential to readily invade newly constructed and disturbed areas (Table 5.1). Control of these species should be the next priority. Prior to mechanical removal, tamarisk dominated much of the low topographic areas along the channel. These areas should be a high priority for monitoring and follow-up treatment, as low lying areas tend to favor passive establishment of native species in arid systems due to relatively high levels of soil moisture.

Tamarisk was mechanically removed from the middle to lower portion of the Fairbanks alignment between 2006 and 2009. Presently many of these individuals are resprouting and setting seed. They are the highest priority for treatment. Additionally, there are large, barren upland areas and slash piles that remain from previous tamarisk treatments. These areas should be revegetated with desirable native species before they are invaded by non-native species. Chipping the remaining slash piles of uprooted tamarisk will provide mulch that can be used to benefit revegetation efforts.

Two vegetation alliances dominate the existing vegetation within the channel construction footprint: Distichlis spicata Intermittently Flooded Herbaceous Alliance and Tamarix species Semi-Natural Temporarily Flooded Alliance (Bio-West 2010; Table 5.2). During construction, soil surface topography (i.e., the addition of swales and hillocks) should be added; the creation of areas with drier soils will favor planted mesquite. Baccharis emoryi Intermittently Flooded Shrubland Alliance is the primary revegetation recommendation for common reed at this site.

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Table 5.1. Weeds recommended for treatment within the Fairbanks Spring construction footprint (a 10-m buffer around the restored channel). The estimated acreage from the Bio-West (2010) Vegetation Map GIS polygons and cover of plants are included. The adjusted acreage is calculated as the sum of the (cover * area) of all polygons. Average acreage = (Adjusted / Estimated acreage) * 100.

Estimated Minimum Maximum Adjusted acreage Average Weeds to be Treated Common Name Acreage Cover (%) Cover (%) (based on cover) Cover (%) Bassia hyssopifolia fivehorn smotherweed 9.04 5 75 1.1 12

Phragmites australis common reed 3.05 5 100 1.3 43

Polypogon monspeliensis annual rabbitsfoot grass 2.03 10 70 0.62 31

Tamarix spp. salt cedar 10.83 5 85 4.5 42

Typha spp. cattail 5.26 5 100 1.25 24

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Table 5.2. Plant community alliances within the Fairbanks Spring Channel construction footprint (within 10m from the channel) and desired species for planting. Species that are relatively easy to propagate and establish are recommended for each species list (See Table 3.2). Planting densities are estimated based on cover at maturity for species. The cost indicates the expense of growing plants.

Cost of Plants for Specified Total Existing Alliance Acreage Replacement Alliance Acreage Cost 2 Juncus arcticus Seasonally Flooded $5,227 $47,115 Mixture of vegetation types within 1m of restored channel

Atriplex lentiformis Shrubland 0.24 $474

Atriplex parryi Shrubland 0.05 $111

5.4 $13,937 Distichlis spicata Intermittently Flooded Herbaceous

Juncus arcticus Seasonally Flooded 0.99 $2,587

Baccharis emoryi Intermittently Phragmites australis 2.04 Flooded Shrubland $4,343 Semipermanently Flooded Herbaceous

Prosopis pubescens Woodland 0.4 $971

Fraxinus velutina-Sporobolus airoides Salix gooddingii Woodland 0.06 Woodland $632

0.74 $1,551 Suaeda moquinii Intermittently Flooded Shrubland

Tamarix spp. Semi-Natural 6.21 Distichlis spicata mixture $16,028 Temporarily Flooded Shrubland

Typha spp. Semipermanently Schoenoplectus americanus Flooded 0.79 Semipermanently Flooded $1,253

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5.3 Soda Spring Channel The Soda Spring Channel alignment is dominated by native vegetation. However, Typha species Semipermanently Flooded Alliance, covers a relatively large amount of the proposed planting area with 41% of the total cover (Table 5.3). After channel construction, Typha could be treated by drying the site and burning along the channel (See Section 4.3.1.14).

Revegetation priorities for the Soda Spring Channel alignment are outlined in Table 5.4. Construction of the Soda Spring Channel occurred in 2010, and the wetland area adjacent to the channel was planted with salvaged plants that compose the Distichlis spicata Intermittently Flooded Herbaceous and Juncus arcticus (balticus) Seasonally Flooded Alliances. Other wetland and upland vegetation alliances should be planted in 2011 and 2012 as outlined in Table 5.4.

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Table 5.3. Weeds recommended for treatment within the Soda Spring construction footprint (a 10-m buffer around the restored channel). The estimated acreage from the Bio-West (2010) Vegetation Map GIS polygons and cover of plants are included. The adjusted acreage is calculated as the sum of the (cover * area) of all polygons. Average acreage = (Adjusted / Estimated acreage) * 100.

Weeds to be Common Estimated Minimum Maximum Adjusted acreage Average Cover Treated Name Acreage Cover (%) Cover (%) (based on cover) (%) Phragmites australis common reed 1.36 10 30 0.21 15

Typha spp. cattail 2.29 10 70 0.94 41

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Table 5.4. Plant community alliances within the Soda Spring Channel construction footprint (within 10m from the channel) and desired species for planting. Species that are relatively easy to propagate and establish are recommended for each species list (See Table 3.2). Planting densities are estimated based on cover at maturity for species. The cost indicates the expense of growing plants.

Cost of Plants for Existing Alliance Acreage Replacement Alliance Specified Acreage Total Juncus arcticus Mixture of vegetation types 0.5 Seasonally Flooded $1,307 $6,456 within 1m of restored channel

Distichlis spicata Intermittently 0.52 $1,336 Flooded Herbaceous

Juncus arcticus (balticus) Seasonally Flooded 0.06 $157

Prosopis glandulosa Shrubland 0.09 $206

Typha species Semipermanently Schoenoplectus americanus Flooded 2.2 Semipermanently Flooded $3,450

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5.4 Rogers Spring Channel The headwater of the Rogers Spring Channel is presently confined to a ditch. The flow will be taken out of the ditch and the reconstructed channel will follow a path similar to that observed in the 1948 aerial photographs. The Rogers Spring Channel crosses through an extensive patch of Phragmites australis (common reed); this alliance is the most prominent alliance within the construction footprint (Table 5.5). Channel construction is likely to favor this species unless it is thoroughly treated, as common reed is tolerant of flooding, and construction will result in the removal of established vegetation. Phragmites is interspersed with Sporobolus at this site, thus the Sporobolus airoides Intermittently Flooded Herbaceous Alliance is the primary revegetation recommendation (Table 5.6). Active revegetation of sites treated for common reed will be vital to long-term control.

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Table 5.5. Weeds recommended for treatment within the Rogers Spring construction footprint (a 10-m buffer around the restored channel). The estimated acreage from the Bio-West (2010) Vegetation Map GIS polygons and cover of plants are included. The adjusted acreage is calculated as the sum of the (cover * area) of all polygons. Average acreage = (Adjusted / Estimated acreage) * 100.

Weeds to be Estimated Minimum Maximum Adjusted acreage Average Treated Common Name Acreage Cover (%) Cover (%) (based on cover) Cover (%) Bassia hyssopifolia fivehorn smotherweed 0.45 10 45 0.15 33

Phragmites australis common reed 3.15 75 75 2.36 75

Tamarix spp. salt cedar 1.77 5 5 0.1 6

Typha spp. cattail 3.22 20 100 0.76 24

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Table 5.6. Plant community alliances within the Rogers Spring Channel construction footprint (within 10m from the channel) and desired species for planting. Species that are relatively easy to propagate and establish are recommended for each species list (See Table 3.2). Planting densities are estimated based on cover at maturity for species. The cost indicates the expense of growing plants.

Cost of Plants for Existing Alliance Acreage Replacement Alliance Specified Acreage Total Juncus arcticus Mixture of vegetation types 0.8 Seasonally Flooded $2,091 $15,286 within 1m of restored channel

Atriplex lentiformis Shrubland 0.03 $59

Baccharis emoryi 2.11 $4,492 Intermittently Flooded Shrubland

Distichlis spicata 0.27 $694 Intermittently Flooded Herbaceous

Juncus arcticus Seasonally Flooded 0.23 $601

3.15 $5,660 Phragmites australis Sporobolus airoides Semipermanently Intermittently Flooded Flooded Herbaceous Herbaceous Prosopis pubescens Woodland 0.65 $1,579

Typha spp. Schoenoplectus americanus Semipermanently Flooded 0.07 Semipermanently Flooded $110

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5.5 Longstreet Spring Channel The lower portion of the Longstreet Spring outflow is currently dominated by common reed, Bassia, and cattail (Table 5.7). As the new channel alignment will flow through areas dominated by this common reed, its treatment is high priority. If common reed is not treated within the vicinity of the spring outflow and the new channel alignment, the weed will undoubtedly spread along the new alignment and most likely alter the restored geomorphology of the channel. The revegetation recommendation for common reed at this site consists of a mixture of the following alliances: Distichlis spicata Sporobolus airoides Herbaceous Alliance, Juncus arcticus Seasonally Flooded Alliance, Prosopis pubescens Shrubland Alliance, and Sporobolus airoides Intermittently Flooded Herbaceous Alliance (Table 5.8).

Once common reed is treated within the channel alignment, treatment of other weeds, followed by wetland plantings and finally upland plantings, are the proposed priorities for this channel alignment. Distichlis spicata is recommended for planting in areas where Tamarix currently grows, and Juncus arcticus should grow well in areas with existing stands of cattail (Table 5.8).

The Longstreet Spring Channel originates near an abandoned agricultural field that has been slow to recover (Figure 5-3). As discussed in the reclaiming of agricultural lands section of this plan, this is a site in need of active revegetation. Unpublished soil data collected by the University of Nevada, Reno (UNR) from a location within the field reports a pH value of 7.54. This is within the range of upland plants that would be expected onsite. It appears that the high amount of solar radiation within the abandoned field might be limiting the natural recovery of plants. However, mesquite species, specifically Prosopis pubescens, are colonizing the site. Cattle, deer, and coyotes have all been shown to facilitate the establishment of mesquite seedlings (Kramp et al. 1998).

Crews should watch for Cardaria draba (hoary cress) while constructing the Longstreet channel, as known populations are present within the perimeter of the 2004 Longstreet Fire (Figure 5-4). If found and treated at an early stage of invasion, control efforts of this weed will be highly successful.

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Figure 5-3. View of the abandoned agricultural field that the Longstreet Channel will flow through.

Carson Slough and Crystal Spring Revegetation | Final Report 71

Figure 5-4. Perimeter of the 2004 Longstreet Fire and location of springs.

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Table 5.7. Weeds recommended for treatment within the Longstreet Spring construction footprint (a 10-m buffer around the restored channel). The estimated acreage from the Bio-West (2010) Vegetation Map GIS polygons and cover of plants are included. The adjusted acreage is calculated as the sum of the (cover * area) of all polygons. Average acreage = (Adjusted / Estimated acreage) * 100.

Estimated Minimum Maximum Adjusted acreage Average Weeds to be Treated Common Name Acreage Cover (%) Cover (%) (based on cover) Cover (%) Bassia hyssopifolia fivehorn smotherweed 4.94 5 60 0.99 20

Phragmites australis common reed 1.84 <5 75 1.39 76

Polypogon monspeliensis annual rabbitsfoot grass 2.39 5 70 0.53 22

Tamarix spp. salt cedar 5.03 <5 25 0.46 9

Typha spp. cattail 6.17 5 90 2.05 33

Salsola paulsenii Russian thistle 0.21 10 10 0.02 10

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Table 5.8. Plant community alliances within the Longstreet Spring Channel construction footprint (within 10m from the channel) and desired species for planting. Species that are relatively easy to propagate and establish are recommended for each species list (See Table 3.2). Planting densities are estimated based on cover at maturity for species. The cost indicates the expense of growing plants.

Replacement Cost of Plants for Existing Alliance Acreage Alliance Specified Acreage Total Juncus arcticus Mixture of vegetation types 2.7 Seasonally Flooded $7,057 $51,417 within 1m of restored channel Atriplex confertifolia Shrubland 0.58 $1,421

Atriplex lentiformis Shrubland 0.59 $1,166

Atriplex parryi Shrubland 0.96 $2,138

Baccharis emoryi 0.19 $405 Intermittently Flooded Shrubland Distichlis spicata 2.54 $6,528 Intermittently Flooded Herbaceous

Juncus arcticus Seasonally Flooded 1.59 $4,156

Phragmites australis 1.84 Multi-Alliance mixture $4,593 Semipermanently Flooded Herbaceous

Prosopis glandulosa Shrubland 0.64 $1,465

Prosopis pubescens Woodland 3.55 $8,621

Schoenoplectus americanus 0.47 $737 Semipermanently Flooded Herbaceous

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Replacement Cost of Plants for Existing Alliance Acreage Alliance Specified Acreage Total Sporobolus airoides 2.76 $4,959 $51,417 Intermittently Flooded Herbaceous

Suaeda moquinii 1.3 $2,725 Intermittently Flooded Shrubland

Distichlis spicata Tamarix spp. Semi-Natural 1.15 mixture $2,968 Temporarily Flooded Shrubland

Schoenoplectus americanus Typha spp. Semipermanently Semipermanently Flooded 1.58 Flooded $2,478

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5.6 Five Springs Channel Revegetation priorities within the Five Springs Channel alignment include the control of Russian knapweed and fivehorn Bassia (Table 5.9), followed by planting of wetland vegetation, and when funding becomes available, the planting of upland vegetation (Table 5.10). The Five Springs Channel runs adjacent to the southern end of a patch of fivehorn bassia (Bassia hyssopifolia) before crossing the Longstreet abandoned agricultural field. Portions of the new channel may evolve into emergent marsh due to the low topographic gradient through the abandoned agricultural field. The construction footprint of the new channel overlaps with a small patch of the Typha Semipermanently Flooded Alliance (Table 5.9). Therefore, weed treatments to control Typha may be necessary along the constructed channel. In addition, installation of an oversized culvert may reduce the amount of Typha on the upstream side of the road.

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Table 5.9. Weeds recommended for treatment within the Five Springs construction footprint (a 10-m buffer around the restored channel). The estimated acreage from the Bio-West (2010) Vegetation Map GIS polygons and cover of plants are included. The adjusted acreage is calculated as the sum of the (cover * area) of all polygons. Average acreage = (Adjusted / Estimated acreage) * 100.

Weeds to be Estimated Minimum Maximum Adjusted acreage Average Treated Common Name Acreage Cover (%) Cover (%) (based on cover) Cover (%) Acroptilon repens Russian knapweed 0.45 5 25 0.06 13

Bassia hyssopifolia fivehorn smotherweed 0.34 5 50 0.04 12

Phragmites australis common reed 0.17 30 30 0.05 29

Typha spp. cattail 0.17 40 40 0.07 41

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Table 5.10. Plant community alliances within the Five Springs Channel construction footprint (within 10m from the channel) and desired species for planting. Species that are relatively easy to propagate and establish are recommended for each species list (See Table 3.2). Planting densities are estimated based on cover at maturity for species. The cost indicates the expense of growing plants.

Cost of Plants for Existing Alliance Acreage Replacement Alliance Specified Acreage Total Juncus arcticus Mixture of vegetation types 0.5 Seasonally Flooded $1,307 $9,053 within 1m of restored channel

Atriplex confertifolia Isocoma acradenia Shrubland 0.01 $25

Prosopis glandulosa Shrubland 1.93 $4,419

Prosopis pubescens Woodland 1.25 $3,036

Schoenoplectus Typha species Semipermanently americanus Flooded 0.17 Semipermanently Flooded $267

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6 CRYSTAL SPRING MANAGEMENT UNIT

The Crystal Spring Management Unit refers to the central portion of the AHME. Channel construction within this area will include four springs: Forest, Kings, Crystal, and Bradford. Forest and King Spring are addressed together as they will be more effectively restored simultaneously. It is expected that channel construction will result in the rising of the water table over approximately 222 acres and that this will result in expansion of emergent marsh habitat (Figure 6-1). This rising of the water table is not included within the acreages of vegetation alliances proposed for planting because unpredictable factors may change the extent of potential marshes shown in Figure 6-1. Marshland (or wetland) vegetation is highly dependent upon soil moisture and these plants should only be planted if the soils in the area are in fact saturated. Following channel construction, any proposed vegetation types may be replaced with wetland vegetation in areas in which the soils become saturated.

Carson Slough and Crystal Spring Revegetation | Final Report 79

Figure 6-1. Crystal Spring Management Unit marshes and the four spring channels that are proposed for construction. The extent of expected conversion to marsh was calculated by Otis Bay Inc.

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6.1 Weed Treatments within the Crystal Spring Management Unit Weed treatments carried out by SWEAT, LLC appear to have been extensive adjacent to the proposed restored channel alignments. Weeds treated include fivehorn bassia, field bindweed, Russian knapweed and saltcedar. However, treatment of bermudagrass and common reed will also be necessary to treat. Ideally, these weeds will be removed from the Crystal Spring Management Unit before channel construction is initiated.

6.2 Forest and Kings Spring Channels The upstream portion of the area around the Forest and Kings Spring Channels contains infestations of fivehorn smotherweed, Russian knapweed, and cattails (Table 6.1). Control of cattails should be coordinated with channel restoration. Cattails could be crushed or excavated during channel construction, followed by the planting of the construction footprint with desired plants. Other weeds will require more specialized treatment. Similar to the other channel alignment restorations, weed control should be followed by planting wetland vegetation and the site should be completed with the planting of upland species. Proposed vegetation alliances for planting and acreages of weed dominated sites are presented in (Table 6.2).

Additionally, Cardaria draba occurs near the Point of Rocks boardwalk area and construction crews should be aware of this weed. Early detection and control of Cardaria draba will reduce spread.

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Table 6.1. Weeds recommended for treatment within the Forest and Kings Springs construction footprint (a 10-m buffer around the restored channel). The estimated acreage from the Bio-West (2010) Vegetation Map GIS polygons and cover of plants are included. The adjusted acreage is calculated as the sum of the (cover * area) of all polygons. Average acreage = (Adjusted / Estimated acreage) * 100.

Kings Spring Weeds to be Estimated Minimum Maximum Adjusted acreage Average Treated Common Name Acreage Cover (%) Cover (%) (based on cover) Cover (%) Acroptilon repens Russian knapweed 2.29 5 15 0.23 10

Bassia hyssopifolia fivehorn smotherweed 0.14 8 85 0.05 36

Tamarix spp. salt cedar 1.67 5 5 0.08 5

Typha spp. cattail 0.08 95 95 0.08 100

Forest Spring Weeds to be Estimated Minimum Maximum Adjusted acreage Average Treated Common Name Acreage Cover (%) Cover (%) (based on cover) Cover (%) Acroptilon repens Russian knapweed 1.25 10 10 0.13 10

Tamarix spp. salt cedar 0.88 10 10 0.09 10

Typha spp. cattail 0.88 40 40 0.35 40

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Table 6.2. Plant community alliances within Kings and Forest Spring Channel construction footprint (within 10m from the channel) and desired species for planting. Species that are relatively easy to propagate and establish are recommended for each species list (See Table 3.2). Planting densities are estimated based on cover at maturity for species. The cost indicates the expense of growing plants.

Kings Spring Cost of Plants for Existing Alliance Acreage Replacement Alliance Specified Acreage Total Juncus arcticus Mixture of vegetation types 1.7 Seasonally Flooded $4,443 $46,008 within 1m of restored channel Atriplex confertifolia Isocoma 2.36 $5,783 acradenia Shrubland

Atriplex confertifolia Shrubland 0.96 $1,900

Atriplex lentiformis Shrubland 0.13 $257

Baccharis emoryi 1 $2,129 Intermittently Flooded Shrubland Distichlis spicata Intermittently 0.06 $154 Flooded Herbaceous

Ericameria nauseosa Shrubland 0.01 $25

Fraxinus velutina-Sporobolus airoides Woodland 1.16 $12,220

Isocoma acradenia Shrubland 1.39 $3,406

Prosopis glandulosa Shrubland 0.05 $114

Prosopis pubescens Woodland 4.46 $10,831

Baccharis emoryi Intermittently Salix exigua Woodland 0.98 Flooded Shrubland $2086

Sporobolus airoides 1.41 $2,534 Intermittently Flooded Herbaceous Typha species Schoenoplectus americanus Semipermanently Flooded 0.08 Semipermanently Flooded $125

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Table 6.2 continued

Forest Spring Replacement Cost of Plants for Existing Alliance Acreage Alliance Specified Acreage Total Juncus arcticus Mixture of vegetation types 0.25 Seasonally Flooded $653 $6,242 within 1m of restored channel

Atriplex confertifolia Shrubland 0.12 $294

Ericameria nauseosa Shrubland 0.01 $25

Prosopis pubescens Woodland 2.17 $5,270

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6.3 Bradford Spring Channel The site of the restored Bradford Spring Channel is currently dominated by a large patch of common reed, Phragmites australis, and at least 150 acres of Russian knapweed, Acroptilon repens, as estimated in the Ash Meadows IPM (USFWS 2006a). The area around Bradford Spring has been treated with herbicide and mowed. Active revegetation of the site took place in the fall of 2008 and 2009 with Sporobolus airoides. The site should continue to be monitored and treated for Phragmites australis and Acroptilon repens as both weeds are still very abundant (Table 6.3). The revegetation recommendation for common reed at this site consists of a mixture of the following alliances: Distichlis spicata Sporobolus airoides Herbaceous Alliance, Juncus arcticus Seasonally Flooded Alliance, Prosopis pubescens Shrubland Alliance, and Sporobolus airoides Intermittently Flooded Herbaceous Alliance (Table 6.4).

The AHME is considering plans to burn the area around the Bradford Spring Channel. The onsite vegetation is currently too dense to access and assess the abundance of weeds, but burning the existing vegetation would make weed patches easier to treat. If fuel loads are high, resulting heat can cause seed mortality. The probability of Russian knapweed seedling emergence is 0.009 or less with a fuel load of 300 g / m2 or more (Vermerie and Rinella 2009). Onsite fuel loads at ground level should be estimated to predict Russian knapweed mortality rates prior to burning. Given that the onsite vegetation is dense, fuel loads are likely high enough to reduce the abundance of Russian knapweed. The response of common reed, Phragmites australis, to fire depends on the season. Burning in winter and spring may increase the density of spring crops. However, burning in the emergence period can lead to high mortality of shoots (van der Toorn and Mock 1982). Given the fire responses of Russian knapweed and common reed, strategically burning this area seems likely to facilitate the control of these weeds.

The native vegetation in close proximity to the channel includes Atriplex lentiformis, Baccharis emoryi, and Prosopis pubescens. A species related to Baccharis emoryi, Baccharis pteroniodes, has been shown to recover through vegetative regrowth in the year following fire (Bock and Bock 1997). Atriplex lentiformis and Prosopis pubescens are both early successional species which could easily be replaced if they did not passively re-establish onsite following fire. Caution should be used when using prescribed fire in the Mojave Desert as vegetation does not always converge with unburned plant species composition even almost 50 years following fire (Abella 2009). However, from a review of the literature on the post-fire response of the plants found in the area of Bradford Spring, prescribed fire might be a useful tool to favor native plants over noxious weeds.

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Table 6.3. Weeds recommended for treatment within the Bradford Spring construction footprint (a 10-m buffer around the restored channel). The estimated acreage from the Bio-West (2010) Vegetation Map GIS polygons and cover of plants are included. The adjusted acreage is calculated as the sum of the (cover * area) of all polygons. Average acreage = (Adjusted / Estimated acreage) * 100.

Weeds to be Estimated Minimum Maximum Adjusted acreage Average Treated Common Name Acreage Cover (%) Cover (%) (based on cover) Cover (%) Acroptilon repens Russian knapweed 1.13 15 80 0.6 53

Bassia hyssopifolia fivehorn smotherweed 1.85 30 50 0.65 35

Cynodon dactylon Bermudagrass 1.73 5 30 0.17 10

Phragmites australis common reed 0.87 100 100 0.87 100

Typha spp. cattail 0.04 100 100 0.04 100

Salsola paulsenii Russian thistle 1.4 30 30 0.42 30

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Table 6.4. Plant community alliances within Bradford Spring Channel construction footprint (within 10m from the channel) and desired species for planting. Species that are relatively easy to propagate and establish are recommended for each species list (See Table 3.2). Planting densities are estimated based on cover at maturity for species. The cost indicates the expense of growing plants.

Cost of Plants for Existing Alliance Acreage Replacement Alliance Specified Acreage Total Juncus arcticus Mixture of vegetation types 0.8 Seasonally Flooded $2,091 $27,449 within 1m of restored channel

Atriplex confertifolia Isocoma 0.24 $588 acradenia Shrubland

Atriplex lentiformis Shrubland 0.56 $1,107

Baccharis emoryi Intermittently 1.85 $3,939 Flooded Shrubland

Fraxinus velutina-Sporobolus airoides Woodland 1.29 $13,589

Juncus arcticusSeasonally Flooded 0.11 $287

Phragmites australis 0.87 Multi-Alliance mixture $2,172 Semipermanently Flooded Herbaceous

Prosopis glandulosa Shrubland 0.33 $756

Prosopis pubescens Woodland 0.79 $1,918

Baccharis emoryi Intermittently Salix exigua Woodland 0.23 Flooded Shrubland $490

Sporobolus airoides 0.25 $449 Intermittently Flooded Herbaceous

Schoenoplectus Typha species Semipermanently americanus Flooded 0.04 Semipermanently Flooded $63

Carson Slough and Crystal Spring Revegetation | Final Report 87

6.4 Crystal Spring Channel The proposed restored Crystal Spring Channel alignment passes through several abandoned agricultural fields. Portions of these fields and the proposed channel are dominated by weeds including fivehorn smotherweed and Russian thistle (Figure 6-2; Table 6.5). Further downstream the channel passes through Upper and Lower Horseshoe Reservoirs, which are currently heavily colonized by cattail (Figure 6-2). Draining the Horseshoe reservoirs and removal of associated dams is a component of the proposed Crystal Spring outflow restoration. Cattail treatment should follow reservoir draining and dam removal. However, it is likely that the lower portions of the restored channel in the vicinity of Horseshoe reservoir will remain emergent marsh habitat, creating favorable conditions for the continued presence of cattail. Any treatment of cattails in this area will have to be followed by the planting of bulrushes to reduce the risk of reinvasion by cattails. Juncus arcticus Seasonally Flooded Alliance is the primary revegetation recommendation for common reed at this site (Table 6.6). Proposed alliances for planting efforts are recommended in Table 6.6.

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Figure 6-2. Overview of the proposed Crystal Spring Channel Alignment and weed patches within the area. Weed patches are from the BioWest vegetation map (2010).

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Table 6.5. Weeds recommended for treatment within the Crystal Spring construction footprint (a 10-m buffer around the restored channel). The estimated acreage from the Bio-West (2010) Vegetation Map GIS polygons and cover of plants are included. The adjusted acreage is calculated as the sum of the (cover * area) of all polygons. Average acreage = (Adjusted / Estimated acreage) * 100.

Weeds to be Estimated Minimum Maximum Adjusted acreage Average Treated Common Name Acreage Cover (%) Cover (%) (based on cover) Cover (%) Bassia hyssopifolia fivehorn smotherweed 2.42 10 90 1.7 70

Cynodon dactylon Bermudagrass 0.98 40 75 0.5 51

Phragmites australis common reed 2.62 5 100 0.71 27

Tamarix spp. Salt Cedar 3.22 10 60 0.63 20

Typha spp. cattail 3.24 5 100 1.67 52

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Table 6.6. Plant community alliances within Crystal Spring Channel construction footprint (within 10m from the channel) and desired species for planting. Species that are relatively easy to propagate and establish are recommended for each species list (See Table 3.2). Planting densities are estimated based on cover at maturity for species. The cost indicates the expense of growing plants.

Cost of Plants for Existing Alliance Acreage Replacement Alliance Specified Acreage Total Juncus arcticus Mixture of vegetation types 1.7 Seasonally Flooded $4,443 $32,769 within 1m of restored channel Atriplex canescens Shrubland 0.14 $312

Atriplex confertifolia Shrubland 0.1 $198

Baccharis emoryi Intermittently 1.21 $2,576 Flooded Shrubland

Chrysothamnus albidus Shrubland 0.12 $193

Distichlis spicata Intermittently 0.05 $129 Flooded Herbaceous

Juncus arcticus Seasonally Flooded 0.68 $1,777

Phragmites australis Juncus arcticus Semipermanently 0.08 Seasonally Flooded $209 Flooded Herbaceous

Prosopis pubescens Woodland 7.5 $18,214

Sporobolus airoides 0.22 $395 Intermittently Flooded Herbaceous

Tamarix spp. Semi-Natural Temporarily 0.12 Distichlis spicata mixture $310 Flooded Shrubland

Schoenoplectus americanus Typha species Semipermanently Semipermanently Flooded 2.56 Flooded $4,014

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7 REVEGETATION FOLLOWING RESERVOIR MODIFICATIONS OR REMOVALS

7.1 Crystal Reservoir Weed treatments and revegetation efforts within Crystal Reservoir will be one of the highest priority aspects of dam removal. The slow decline in water table depth associated with reservoir drawdown creates ideal conditions for tamarisk establishment. Drawdown of the reservoir should be timed not to coincide with the seed dispersal period of tamarisk in later summer. Declining water levels at this time will facilitate the establishment of tamarisk.

Tamarisk within close proximity to the reservoir has already been treated. As tamarisk resprouts readily following most treatment efforts, known treatment areas are included within the extent of the reservoir for a total of 126 acres proposed for planting. The cost of re-treating these areas is not included in the budget but should be if tamarisk individuals around the reservoir are observed resprouting. Downstream areas should be monitored for invasion by tamarisk as well as other weeds during reservoir drawdown and following dam removal.

The area surrounding the reservoir is dominated by Atriplex confertifolia Shrubland Alliance, Distichlis spicata Intermittently Flooded Herbaceous Alliance, Typha species Semipermanently Flooded Alliance, and Sporobolus airoides Intermittently Flooded Herbaceous Alliance (Figure 7-1, olive green, aqua, light green and pink respectively). The Typha alliance will become desiccated as the reservoir is drained. Tilling the soils in these areas will facilitate establishment of desirable species. The Atriplex confertifolia Shrubland Alliance, Distichlis spicata Intermittently Flooded Herbaceous Alliance, and Sporobolus airoides Intermittently Flooded Herbaceous Alliance communities will all be ideal target communities in this setting, and the revegetation design calls for planting these vegetation alliances (Table 7.1).

The area is currently dominated by saltgrass (Distichlis spicata Intermittently Flooded Herbaceous Alliance and Typha species Semipermanently Flooded Alliance). Therefore, we propose that the Distichlis Alliance be planted at 40% cover (50.4 acres) and the Atriplex confertifolia Shrubland and Sporobolus airoides Intermittently Flooded Herbaceous Alliances each be planted at 30% cover (37.8 acres). As with the restored channel alignments, this will result in 20% of the ideal cover of Atriplex confertifolia Shrubland Alliance (upland plantings) and 10% of the ideal cover of Distichlis spicata Intermittently Flooded Herbaceous Alliance and Sporobolus airoides Intermittently Flooded Herbaceous Alliance (wetland plantings).

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Table 7.1. Revegetation priorities within Crystal Reservoir. See Table 3.2 for plants associated with each alliance.

Revegetation Proposed Vegetation Alliances Acreage Cost of Plants Priorities Upland Types Atriplex confertifolia Shrubland Alliance 37.8 $22,445

Distichlis spicata Intermittently Flooded 50.4 $51,812 Herbaceous Alliance 37.8 $20,376 Sporobolus airoides Intermittently Flooded Herbaceous Alliance Total $94,633

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Figure 7-1. Crystal Reservoir and surrounding vegetation alliances (BioWest 2010). Saltcedar treated by SWEAT, LLC is hatched in bright yellow. Some of the more common vegetation alliance codes are: ATCO_SL- Atriplex confertifolia Shrubland, ATCOISAC2_SL- Atriplex confertifolia Isocoma acradenia Shrubland, ATLE_SL- Atriplex lentiformis Shrubland, BAEM_IFSL- Baccharis emoryi Intermittently Flooded Shrubland, CHAL9_SL- Chrysothamnus albidus Shrubland, DISP_IFH- Distichlis spicata Intermittently Flooded Herbaceous, DISPSPAI_H- Distichlis spicata Sporobolous airoides Herbaceous, FRVE2_WD- Fraxinus veluntina Woodland, ISAC2_SL- Isocoma acradenial Shrubland, JUAR2_SFL- Juncus articus Seasonally Flooded Alliance, LATR2AMDU2_SL- Larrea tridentata Ambrosia dumosa Shrubland, PHAU7_SFH- Phragmites australis Semipermanently Flooded Herbaceous, PRGL2_SL- Prosopsis glandulosa Shrubland, PRPU_W- Prosopis pubescens Woodland, SCAM6_SFH- Schoenoplectus americanus Semipermanently Flooded Herbaceous, SPAI_IFH- Sporobolous airoides Intermittently Flooded Herbaceous, SUMO_IFSL- Suaeda moquinii Intermittently Flooded Shrubland, and TYPHA_SPP_SPL- Typha species Semipermanetly Flooded. 94 Otis Bay Ecological Consultants

7.2 Mud Lake Dam Reservoir Mud Lake Dam consists of 12.9 acres of successfully treated tamarisk and other weeds (Figure 7-2). With the exception of fivehorn bassia, additional weed treatments are not needed at this site at this time. It is advised that the site be monitored for future invasions. Revegetation efforts will reduce the likelihood of future weed invasions.

Most of the surrounding area is Atriplex confertifolia Shrubland Alliance. Plans to restore the area include removing the dam and reconstructing an ephemeral stream channel. The ephemeral channel should be planted with the Prosopis pubescens Shrubland Alliance (approximately 0.5 acres), and the surrounding area should be planted as Atriplex confertifolia Shrubland Alliance (approximately 12.4 acres) (Figure 7-3; Table 7.2).

Figure 7-2. Mud Lake Dam Reservoir. This photo, taken in August 2009, shows tamarisk in the upper left of the photo and fivehorn bassia that has died as a result of weed treatments throughout the abandoned reservoir.

Table 7.2. Revegetation priorities within Mud Lake Dam Reservoir. See Table 3.2 for plants associated with each alliance. Revegetation Proposed Vegetation Alliances Acreage Cost of Plants Priorities Upland Types Atriplex confertifolia Shrubland Alliance 12.4 $24,542

Prosopis pubescens Shrubland Alliance 0.5 $1,214

Total $25,757

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Figure 7-3. Mud Lake Dam Reservoir planting. Proposed planting for the site includes screwbean mesquite (Prosopis pubescens) along a reconstructed ephemeral stream channel and shadscale (Atriplex confertifolia) in the uplands.

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7.3 Peterson Reservoir Peterson Reservoir is the terminus of the proposed Fairbanks, Rogers, and Longstreet Channel alignments. Revegetation efforts should focus on areas where weeds are being treated ( Figure 7-4). A number of weed infestations occur upstream of Peterson Reservoir according to the vegetation map (Bio-West 2010), and they should be eradicated before continuing with the treatment of infestations around the reservoir (Figure 5-2). SWEAT, LLC has treated fivehorn bassia, red brome and saltcedar within the vicinity of the reservoir. Appropriate vegetation alliances for revegetation efforts include the Distichlis spicata Intermittently Flooded Herbaceous Alliance and the Atriplex confertifolia Shrubland Alliance.

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Figure 7-4. The current extent of Peterson Reservoir overlaid on the aerial photography from 1948. A large portion of the area was marsh prior to construction of the berm which allowed increased water storage. As presently proposed, the reservoir will be maintained as open water and emergent marsh.

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8 REVEGETATION OF ABANDONED AGRICULTURAL FIELDS

Abandoned agricultural fields are often difficult to revegetate due to soil disturbance, nutrient depletion, and loss of native seedbanks. Key soil attributes to examine and amend if necessary are soil structure, texture, fertility, organic matter, soil organisms and soil crusts. Selected species for revegetation efforts should be adapted to environmental conditions (e.g., high soil salinity, high solar radiation/low soil moisture) to facilitate establishment of less disturbance-tolerant species.

8.1 Soil Assessment and Amendments Mulch, soil amendments and surface shaping will increase soil fungal and faunal activity. Additionally, reducing soil compaction will improve water infiltration and facilitate root growth. Without inverting the soil layers, soils should be broken up as deeply as possible by tilling or ripping. An acceptable range of soil bulk density is below 1.5 oz/in3. Adding mulch with a high C:N ratio will support fungi and microarthropods, further improving the soil and making mineral nitrogen available to plants. Weed- free rice straw is recommended for this purpose. Spreading rice straw on abandoned agricultural fields prior to ripping along the contour will achieve these goals and minimize erosion. These ripped contours also create microtopography. The bottom of each ripped furrow will accumulate seed and precipitation, facilitating passive recovery of vegetation.

Fine, wind-blown materials are often fertile and can improve soil texture. Wind fences and vertical mulch will capture these fine materials. Re-establishing plants will also speed recovery by capturing fine materials and improving soils through their own growth and development. For example, one species of mesquite (Prosopis juliflora (Swartz) D.C.) was shown to desodify soils, improving pH, electrical conductivity and the availability of nutrients such as P, K Ca2+, Mg2+ (Mishra and Sharma 2003). Additionally, resulting decreases in bulk density improved water infiltration and water holding capacity.

Although soils may have low fertility, application of fertilizer is only recommended if plants will be irrigated. The addition of supplemental nutrients may result in plants depleting available soil moisture early in the season. Nitrogen and potassium can depress or prevent natural inoculation by soil symbionts and fungal hyphae, which may result in limited plant nutrition and water availability.

Cryptobiotic crusts reduce erosion, increase infiltration, make soil nitrogen available at the surface and improve soil structure. Passive recovery of cryptobiotic crusts may range in time from only 6 years for trampling disturbance in cool deserts (Belnap and Eldridge 2003) to millennia in the hottest, driest portions of North America (Belnap and Warren 1998). These crusts possess several life history traits that increase their ability to colonize severe environments: wind dispersal of small propagules (Lewis Smith 1993), desiccation tolerance (Oliver et al. 1993), photoprotective pigments (Bowker et al. 2002), nitrogen fixation (Evans and Ehleringer 1993) and carbon fixation (Lange et al. 1994). However, if cryptobiotic crusts grow in neighboring sites they can be salvaged and spread over a revegetation site. Crusts can be salvaged dry (Belnap 1993) or mixed in a slurry and then spread (St. Clair et al. 1984). Both of these studies showed enhanced recovery of cryptobiotic crust, although crusts did not become as fully developed as at undisturbed sites within the time period of the studies.

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If available, topsoil salvage is the most valuable soil treatment (Bainbridge 2007). Salvaged topsoils often contain high levels of nutrients, cryptobiotic crusts, vesicular arbuscular mycorrhizal fungi, and seeds. Leaving some plant material onsite, the top two inches of the profile should be salvaged, transported, and if necessary, stored with care. Ideally, salvaged topsoil will be spread immediately. If this is not possible, soils can be stored in dry, steep, shallow piles to maintain microorganism and seed vitality (Bainbridge 2007). Higher soil moisture decreases the survival of vesicular arbuscular mycorrhizal fungi by allowing spores to germinate. Soils should be used as soon as possible, although the use of older topsoil is better than none at all.

Given the size of the agricultural fields, inoculating plants with native top soil in the nursery or the field is likely to be more cost-effective than inoculating entire fields. Native soils, taken from under the canopy of healthy donor plants, should be used for inoculation. It is beneficial if these soils are collected under species that will be inoculated. No more than 10% of the soil surrounding a donor plant should be removed. A half a cup of soil in the plant container or planting holes should be sufficient to achieve inoculation. Inoculated nurse plants can also be used to promote the soil microbe community (Middleton and Bever 2010). Dispersed planting of inoculated individuals in the vicinity of uninoculated plants encourages spread of beneficial soil organisms and reduces cost.

8.2 Planting Due to the severity of environmental stresses that will be experienced by establishing plants on abandoned fields, containerized plantings are recommended. Inoculating some plants from salvaged soils is also recommended, though inoculating soils at a site is not always successful. A small amount of native soil can be layered in plant containers or planting holes to inoculate roots. Islands of inoculated plants should facilitate site inoculation. Augering deep holes for plantings will improve plant establishment and survival. Augering increases the depth of water infiltration and facilitates deep root growth.

8.3 Irrigation Irrigation is necessary to ensure successful revegetation efforts in arid and highly exposed landscapes. High exposure leads to decreased soil moisture and increased plant stress. In close proximity to spring channels, a pump with a gas, diesel or solar engine can be used with water from the channel. A screen intake should be used to ensure that no fish are entrained. The soil profile should be wetted to 4” and kept moist until plants are established. Use of drip emitters or deep pipes will reduce evaporative irrigation loss. Excessive water use can result in soil crusting and salt accumulation, thereby, causing damage to the soil structure and buildup of soluble salts.

Some abandoned agricultural fields slated for revegetation are located at substantial distances from the nearest spring channel alignment. Water storage tanks in combination with drip emitters into deep pipes, manual labor to water deep pipes, or DriWater® (see Section 4.5.2 above) are all irrigation options in these fields.

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8.4 Monitoring of Revegetation Efforts Monitoring of plantings should occur monthly for the first year and at least quarterly thereafter over several years. Abandoned agricultural fields are exceptionally stressful for plant establishment and growth, as indicated by the paucity of vegetation onsite. Monitoring allows detection of potential problems before they become serious, such as weed invasions and plants receiving inappropriate amounts of water. Monitoring will also elucidate ways to improve future efforts through the refinement of soil preparation techniques, species planting lists, etc.

Given that exposure and low soil moisture are likely to hinder plant growth and establishment, the facilitation effects of temporary shade structures could be tested on transplants (Hastwell and Facelli 2003). While the benefit of shade structures has been debated in the literature, regular weekly monitoring could determine if the use of shade structures increases success of revegetation. Small structures could be made with Weathashade shadecloth suspended above the ground with wooden posts (Hastwell and Facelli 2003). Shade may be beneficial to transplants in summer but detrimental in winter. Constructing smaller, more mobile shade structures would allow revegetation staff to move them seasonally.

8.5 Agricultural Field Selection for Active Revegetation Agricultural fields were prioritized for active revegetation efforts based on the amount of passive recovery of native vegetation and density of weedy species. With the exception of patches of tamarisk and the Longstreet abandoned agricultural field, the agricultural fields within the vicinity of the Fairbanks and Rogers Channels are already dominated by native vegetation. Thus active revegetation of these agricultural fields is lower priority. It is recommended that weed treatments and revegetation of constructed channels and restored reservoirs be the focus of revegetation within the AHME. However, two agricultural fields in the vicinity of the Point of Rocks Spring Channel and the Longstreet Spring Channel are lacking in native vegetation and should continue to receive treatment due to high weed cover (Figure 8-1). Plans for restoration of these fields follow.

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Figure 8-1. Agricultural fields proposed for active revegetation: fields near the Point of Rocks Spring (top) and field near the Longstreet Spring (bottom).

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8.6 Point of Rocks In the vicinity of the Point of Rocks Spring, 38.7 acres are proposed for active revegetation (shown in pink, Figure 8-1; Figure 8-2). Plantings should be established in patches over 20% of this area. From an examination of the surrounding area, equal proportions (2 acres) of the following vegetation alliances are recommended for planting: Atriplex confertifolia Shrubland Alliance, Isocoma acradenia Shrubland Alliance, Prosopis glandulosa Shrubland Alliance, and Prosopis pubescens Shrubland Alliance (Table 8.1). An additional 17.5 acres are in need of bermudagrass treatment and active revegetation. SWEAT, LLC has treated a number of weed infestations within the vicinity of this abandoned agricultural field, including: fivehorn Bassia, field bindweed, saltcedar, and Russian knapweed. Revegetation of these areas is only recommended if weed treatments have resulted in control of treated species. Onsite field surveys are needed to evaluate the effectiveness of these treatments.

Figure 8-2. Abandoned agricultural fields at Point of Rocks with saline soils.

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Table 8.1. Revegetation priorities within the Point of Rocks Abandoned Agricultural Fields. See Table 3.2 for plants associated with each alliance. Revegetation Proposed Vegetation Alliances Acreage Cost of Notes Priorities Plants Upland Types Atriplex confertifolia Shrubland Alliance 2 $3959 The costs included here are only the cost Isocoma acradenia Shrubland Alliance 2 $4900 of producing plants. Soil preparation, Prosopis glandulosa Shrubland Alliance 2 $4579 installation, plant inoculation, irrigation, Prosopis pubescens Shrubland Alliance 2 $4857 and monitoring costs will need to be included. Total $18,295

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8.7 Longstreet The Longstreet abandoned agricultural field encompasses approximately 97.3 acres. An examination of historical aerial photography of the field shows a dramatic increase in cover of mesquite between 1982 and 2006 (Figure 8-3). Although a limited area surrounding the field has been classified as Prosopis pubescens Shrubland Alliance, the establishment of mesquite into this field has been more prominent than the establishment of any other species.

Previous work has shown that mesquite seedlings can establish from the feces of deer, cattle and coyote (Kramp et al. 1998) as well as Merriam kangaroo rats. Merriam kangaroo rats are more likely to facilitate the establishment of mesquite in areas of low perennial grass cover. Additionally, this condition is cyclic in that mesquite dominates and eliminates perennial grasses (Reynolds 1954).

Soil data were collected within the abandoned agricultural field near the Longstreet Spring (Table 8.2). For comparison, data from two samples that were taken west of the field within the Distichlis spicata Intermittently Flooded Herbaceous Alliance and data from one sample taken east of the field within the Atriplex confertifolia Isocoma acradenia Shrubland Alliance are also shown. The data taken from within the abandoned agricultural field appear to be similar to the nearby native plant communities. However, electrical conductivity (a proxy for salinity) appears to be significantly lower in the abandoned field (Table 8.2). Lower values of electrical conductivity may be due to halophytic species moving salts out of the groundwater and to the soil surface (Barrett-Lennard 2002). The lower electrical conductivity value within the abandoned agricultural field will reduce the amount of stress encountered by plants in active revegetation efforts.

It is recommended that 20% of the approximately 97.3 acres of the Longstreet abandoned agricultural fields be actively revegetated to provide seed sources of desirable species to the remaining area (Table 8.3).

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Table 8.2. Soil data collected within and near the Longstreet Abandoned Agricultural Field.

Dominant Vegetation Alliance Soil Phosphorus Electrical Ammonium Nitrate Percent Sand Percent Silt Percent Clay pH (mmol/kg) Conductivity (mmol/kg) (mmol/kg) (siemens / meter) Longstreet Abandoned Agriculture 7.54 0.15 0.9 0.43 0.97 53.3 29.0 20.0 Distichlis spicata Shrubland Alliance (1) 8.11 0.11 10.6 0.09 0.33 77.7 13.7 8.8 Distichlis spicata Shrubland Alliance (2) 8.42 0.21 26.3 0.22 0.60 47.0 36.0 18.1 Atriplex confertifolia 7.67 0.06 5.12 0.12 0.25 52.4 73.1 16.7 Isocoma acradenia Shrubland Alliance

Table 8.3. Revegetation priorities within Longstreet Abandoned Agricultural Field. See Table 3.2 for plants associated with each alliance. Revegetation Proposed Vegetation Alliances Acreage Cost of Notes Priorities Plants Upland Types Atriplex confertifolia Shrubland Alliance 7.8 $15,438 Soil preparation, installation, plant inoculation, irrigation, Distichlis spicata Shrubland Alliance 4.0 $10,280 and monitoring costs are not included. Prosopis pubescens Shrubland Alliance 7.8 $18,942 Total $44,660

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Figure 8-3. Abandoned agricultural field at Longstreet Spring. The aerial image on the left was taken in 1982, and the image on the right is the 2006 NAIP. The screwbean mesquite trees that are visible in the NAIP imagery were not visible at the time of the 1982 photo when agriculture was still underway. Carson Slough and Crystal Spring Revegetation | Final Report 107

9 CONCLUSION

Although weed infestations are a major issue throughout the AHME, SWEAT, Conservations Services, and AHME staff have implemented numerous effective treatments. Regular monitoring of these efforts will be necessary for long-term success of weed control.

The success of revegetation and native plant establishment adjacent to the proposed restored channel alignments will depend upon the control of weed infestations near each channel and, to a lesser extent, throughout the AHME. Seed sources of undesirable species increase the risk of future invasions. Active revegetation within the restored channel footprints will be necessary to prevent invasion by weeds that, if established in close proximity to restored channels, could change the morphology and hydrology of the restored channel.

With few exceptions, the same list of priorities should be employed on all of the restored channel alignments. First, weed control is of the greatest importance to prevent spread of noxious species. Secondly, planting wetland vegetation will hinder the establishment of these weeds if the desirable plants occupy a given site first. Wetland vegetation tends to recover naturally and quickly from disturbance given sufficient soil moisture. The only labor required to establish these vegetation types should be collection and planting of materials. The most expensive and challenging revegetation work will be establishment of upland plants. Given the stressful growing conditions of the Mojave Desert, containerized plantings are likely to be worth the extra expense. If properly irrigated, containerized plants are more likely to survive to maturity than plants established from direct seeding.

Restoration of anthropogenically disturbed areas, such as reservoirs and abandoned agricultural fields, will also enhance assemblages of diverse habitats within the AHME. Modification or removal of reservoirs will promote recovery of hydrologic processes and remove source areas of invasive plants (especially Tamarisk and Bassia). Restoration of old fields will eliminate areas of future weed invasion or existing sources of invasive plants (especially knapweed). Restoration of these disturbances will increase habitat for wildlife species within ASME.

This revegetation plan is a work in progress. As funds become available to implement this plan, it is possible that site conditions will change. Each restored channel alignment or disturbed site should be revisited by a plant ecologist before final plans are made for their restoration.

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