National Park Service

Lake Mead National Recreation Area

Arid Land Restoration

at Lake Mead NRA

Alice C. Newton

Vegetation Management Specialist

You have to get over the color green; you have to quit associating beauty with gardens and lawns; you have to get used to an inhuman scale; you have to understand geological time.

Thoughts in a Dry Land, Wallace Stegner

We’ve mined it, dammed it, irrigated it, developed it, and subjected it to nuclear assault, yet the desert, somehow both fragile and tough, manages to endure, a rugged old touchstone for us to measure ourselves against.

Malcolm Jones Jr. 1996

The finest quality of this stone, these plants and animals, this desert landscape is the indifference manifest to our presence, our absence, our coming, our staying or our going. Whether we live or die is a matter of absolutely no concern whatsoever to the desert.

Desert Solitaire, Edward Abbey

In the desert, you see, there is everything and nothing. It is God without mankind.

A Passion in the Desert, Honore de Balzac

What Good Is A Desert?

What Good Is A Desert?

• Aesthetics

• Solitude

• Survival challenge

Why Restore The Desert?

• NPS Policies – because it’s our job!

• Other applicable laws

• Economics

• Environmental factors

NPS Policies• [The National Park Service] shall promote

and regulate the use of the Federal areas known as national parks, monuments and reservations …which purpose is to conserve the scenery and the natural and historic objects and the wild life therein and to provide for the enjoyment of the same in such manner and by such means as will leave them unimpaired for the enjoyment of future generations.

NPS Organic Act of 1916

NPS Policies• 2006 Management Policies

– Preserving park resources and values unimpaired is the core or primary responsibility of NPS managers

– The Service will reestablish natural functions and processes [disturbed by human impacts] in parks unless otherwise directed by Congress

– Natural disturbances [landslides, fire, etc.] will be allowed to recover without human intervention whenever possible

Other Applicable Laws

• Wilderness Act

• Endangered Species Act

• Federal Water Pollution Control Act (Clean Water Act)

• Clean Air Act

Economic

• Recreation

• Tourism

• Flood control

• Mitigation for other disturbance or “takings”

Environmental

• Rare plant and animal habitat

• Common plant and animal habitat

• Ecosystem services– Air Quality (PM10 reduction)– Watershed function– Carbon sequestration– Nutrient cycling

Challenges

• Soils based, not vascular plant based

• Key soil stabilizers are cryptobiotic crusts and cyanobacteria, rock armor, physical crusts

• Key nitrogen fixers are cryptobiotic crusts and cyanobacteria

• Unique hydrology resulting from chemical pan development – localized underground sheet flow

Challenges

• Extremely long-lived seed banks

• Recovery trajectories can be extremely long – sometimes decades

• Recovery trajectories are not linear

• Transition thresholds are not well known

• Historic community composition and range of variability is not well known

Guiding Philosophy

• Work on the cause as well as the effect

• Methods are simple to implement and understand

• Time is on our side – Jump Start

• Form Follows Function

• Soil building and hydrologic processes are key

• Minimize input as much as possible

Types of Disturbance

• Chronic and Dispersed– Grazing– Fire– Dust and Nitrogen Deposition

• Acute and Discrete– Off-Road Vehicles– Mining– Construction– Pipelines

Restoration Methods

• Choosing Appropriate Methods– Type of soil, crust– Degree and type of damage– Natural recovery potential– Potential for redisturbance– Time available for recovery– Resources available– Size of disturbance – Political or regulatory considerations– Sometimes best to leave it alone!

Soils and Water Management

• Topsoil salvage and replacement

• Recontouring

• Decompaction

• Raking

• Erosion control

• Soil amendments and horizontal mulch

• Vertical mulch

Soils and Water Management

• Rock mulch

• Artificial desert varnish

• Tackifiers

• Biotic crust inoculation

• Fertilizer and “anti-fertilizer”

• Water retention and infiltration

Plant Establishment• Topsoil salvage• Transplants from site to site (plant

salvage)• Transplants from nursery stock• Seeding• Natural dispersal (linear features only)

• Transplants require at least two summer seasons of supplemental watering

Topsoil Salvage

• Less expensive per plant in the long run

• Obtain full range of species – annual and perennial plants, soil microbiota, and sometimes arthropods as well

• Must be handled gently with minimal storage time

• Germination and establishment generally follows successional path

Plant Salvage

• Establish structure• Create immediate camouflage• Brings community biota along (for good

and bad)• Destroys donor site• Labor intensive• Limited species• Can have high mortality (but then

becomes vertical mulch!)

Nursery Transplants

• Much lead time required for seed collection and propagation

• Can be very expensive

• Limited/biased genetics

• Limited species

• High nitrogen content means extensive herbivory problems

Seeding

• Extremely limited supply and low viability

• Limited species and genetics

• Much lead time required

• Extremely high loss to UV, desiccation, and granivory

• Potential for weed introduction

• Can be very slow to establish leaving unoccupied areas for weeds

Natural Dispersal• Recommended for small or linear features

only• Full range of species available• Full genetic range available• No outside genetics introduced• Low cost but weeds must be managed• Niches must be open• Very slow to establish

Site Protection and Maintenance

• Wire cages

• Tree Shelters

• Rocks and mulch

• Vertical mulch

• Barriers

• Weed management

• Supplemental watering

Monitoring

• Determine “success” – may have nothing to do with vascular plant cover

• Have realistic expectations

• Be prepared for long recovery trajectories

• Publicize your success

Where Do We Go From Here?

• Seed pelleting project

• Soil development experiments

• Gypsum habitat restoration experiments

• Cryptobiotic crust inoculatons

• Other ideas?

Contact Info

• Alice C. Newton• Vegetation Management Specialist• Lake Mead National Recreation Area• 601 Nevada Way• Boulder City NV 89005

• Alice_corrine_newton@nps.gov

• Any questions?