Mogollon Highlands Ecoregion Overview

The Mogollon Highlands of Arizona is an impressive landscape of more than 300 km of rugged escarpments, forests, deserts, canyons, mesas. The Mogollon Rim is a one of Earth’s longest escarpments comprised of lava flows and striking sandstone and limestone formations. The elevation of the Transitional zone averages between 1,200 – 1,500 m, exceeding 2,130 m along the Rim. Ecologically, the Highlands is where Mexico meets Canada. The Rim is a biodiversity hotspot and has high endemism, and remarkable ecological and sociocultural diversity. This ecological transition zone encompasses plant and animal species common to the Colorado Plateau and the Southern Rocky Mountains to the north, and those of the Transition Ranges and Sierra Madre Occidental of western Mexico to the south.

WHAT IS THE MOGOLLON HIGHLANDS ECOREGIONAL CONSERVATION ASSESSMENT (ECA)?

The Mogollon Highlands Ecoregional Conservation Assessment (ECA) is an ecosystem level approach by which habitat and biodiversity conservation priorities are assessed, based on the status of flora and fauna biodiversity. Over half the region is under federal ownership, and 13% is owned by tribes.

Our focus is on mature/ old-growth (MOG) forests, pinyon-juniper woodlands, riparian areas and assessing the potential for recovery of the endangered Mexican wolf (Canis lupus baileyi), and grizzly bear (Ursus arctos horribilis) back into the region. This ECA examines habitat condition, status of biodiversity, and threats in the ecoregion when setting actionable goals for conservation.

The ecoregional boundary for our study area is derived collaboratively from a working group composed of a coalition of stakeholders including nonprofit organizations and US EPA Level III mapping classifications. Ecoregions are hierarchical, ranging from Level I, the broadest classification, to Level IV, the most detailed. EPA Level III classifications retain data from Levels I and II and divide the continental United States into 104 ecological regions identified by geology, physical geography, vegetation, climate, soils, land use, wildlife, and hydrology. We overlaid the Gila Bioregion onto the eastern portion of the boundary.

Our ECA is based on a scientific approach that includes constructing layers of representative geographic data, key biodiversity attributes, and ecosystem stressors/ threats in geographic information systems (GIS). We incorporate downscaled AR5 climate projections developed by the Intergovernmental Panel on Climate Change (IPCC) and conducted an expert workshop to determine specific conservation needs and opportunities.

peterv, Arizona landscape, Mogollon Rim, canva.com, accessed November 8, 2023.

peterv, Arizona landscape, Mogollon Rim, canva.com, accessed November 8, 2023.

About the Mogollon Rim Highlands ECA

Vegetation and Forests of the Mogollon Highlands

Arizona has the third highest plant species richness of any state, with much of it found in the Mogollon Highlands. This region includes 62 groups of plant communities (LANDFIRE). This ECA primarily focuses on forests, woodlands, and riparian areas threatened by aggressive fire management and land-uses. Forests and open woodlands comprise nearly 1/2 of the study area, dominated by Pinyon-Juniper Woodlands and Ponderosa Pine Forest, Woodland and Savanna vegetation groups. Riparian areas comprise only 0.5% of the study area and are dominated by cottonwood, aspen, shrubs, forb, and grass species.

Pinyon-Juniper Woodlands grow to under 15 m tall and primarily grow at elevations ranging from 1,500-2,440 m. Ponderosa pines can grow to nearly 46 m. tall and primarily grow at elevations above 1,500 m.  Pinyons, junipers, and ponderosa pines are drought tolerant and long-lived (e.g., Ponderosa pines can live to 700 years, juniper to 650 years). Many species of mammals, birds, and insects utilize these trees for food and shelter.  Ponderosa pine species shares a symbiotic relationship with an underground fungus – mycorrhizae – each providing important nutrients to the other. 

Photo credit: D. DellaSala 

Mature and old growth (MOG) forests are a subtype of the vegetation groups that have distinct ecological values nation-wide. For more information on MOG mapping, please watch MOG Presentation video and read our section on Regional Mature and Old-growth Forest (MOG) Maps for the Lower 48 States.

Importance of Riparian Areas and Springs

Arizona is the second most arid state in the U.S.; thus, water in the form of rivers, streams, and springs – often isolated by arid, expansive landscapes – is a critical resource in the Mogollon Highlands.

Riparian zones, the interface between terrestrial and aquatic habitat found along the edges of water bodies, provides a multitude of important functions. They improve water quality and stabalize streambanks, slowing erosion.

Springs occur where groundwater is exposed. They may have very little water flow (ie. seeps), or large flows creating rivers.

Representing less than 1% of the vegetation types found in out study area, riparian zones and springs are extremely important for conservation as they are hotspots for flora and fauna biodiversity.


Photo credit: humblebleufrog, “Arizona mountain stream”,
canva.com, accessed Nov. 9, 2023. 
Mexican Wolf and Grizzly Bear

The study area is home to the endangered Mexican wolf, a species indigenous to the Southwestern U.S. Recovery efforts for this species, which was listed as endangered by the U.S. Fish and Wildlife Service (USFWS) in 1976 following extirpation in the wild through private and governmental control campaigns, have been in progress for more than three decades. Recovery efforts have included captive breeding and subsequent reintroduction into the central parts of Arizona and New Mexico. The preferred habitat of the Mexican wolf was woodlands (pine, oak, and pinyon-juniper) and adjacent grasslands, which provided cover, water and hunting of ungulates and small mammals. Riparian corridors are also surmised as being important for travelling and hunting prey, and connectivity higher in areas that have experienced less pressure from human development, including the central portion of the study area and in the Gila Bioregion to the east.

Grizzly bears were largely exterminated from the southwestern U.S. by the 1930s. In the Mogollon Highlands Ecoregion, nearly 30% of the area is suitable habitat for grizzly bears, especially in the Gila Bioregion, notably providing high-quality foods and remote enough from human infrastructure to allow them to survive and reproduce. Initiatives for reintroduction of the grizzly bear and expansion of Mexican wolves need to be coordinated with interested tribes in the region.

Photo credit: Woodkern, “Endangered Mexican wolf,”
canva.com, accessed Nov. 9, 2023.
Land Ownership and GAP Analysis project status

Nearly 55% of our study area is under federal management, followed by private (20%) and Tribal (13%) ownership.

 
Photo credit: D. DellaSala

Gap Analysis Project (GAP) management status codes were applied to our study area using spatial analysis data provided by the U.S. Geological Survey. GAP 1 (e.g., Wilderness, National Parks) and GAP2 (e.g., National Monuments) are considered protected lands. GAP3 (e.g., Inventoried Roadless Areas) is multiple use management and GAP4 receives few to no protections. Most of the study area fall into GAP3 and 4, having multiple use or little to no protections.

Inventoried Roadless Areas (IRAs) are ecologically intact public lands that exclude open roads or major development or infrastructure. When IRAs are elevated to protected status above GAP 2, they may be redesignated as “wilderness.” They are important refugia for biodiversity and supporting populations of animal species that rely on habitat free from human disturbance, including the Mexican wolf and grizzly bear. IRAs are designated as GAP3 multiple use management in the PAD-US dataset. We classified IRAs in our study as GAP2.5 because they are protected from most forms of logging. By elevating IRA protections, mature and old-growth forest protections within these IRAs would be also improved.

Scientists and policymakers have recently set a goal of protecting 30% of the Earth by 2030 (“30×30”) as an interim step to protecting 50% of the Earth by 2050. Elevating protections of IRAs in the Mogollon Highlands and elsewhere, could contribute to the largescale global protection goal.

Wildfire Urban Interface and Wildfires
Photo credit: dmytrogilitukha, “Forest Fire”, canva.com, accessed Nov. 9, 2023.

Wildfire is and always has been an integral part of Western forest ecosystems. Many species are highly reliant on wildfire, and burned areas experience bursts in diversity as they regenerate after fire. Thus, while wildfire is considered a threat to human development and safety, it is not inherently a negative occurrence at the landscape level.

The number of days with “high” fire danger is projected to increase across our study area.

Drought and wildfire are closely linked in the Southwest. Pinyon pine (Pinus edulis and others), ponderosa pine (Pinus ponderosa), juniper, oak (Quercus spp.), and numerous other species have all shown extensive dieback and defoliation due to extended drought conditions. In a survey of juniper in the Cononino, Kaibab, and Prescott National Forests in 2021, more than 85% were experiencing dieback attributed to drought. In addition, more than 1,700 sq. km of state land had observable drought impacts and 2,000 sq. km were affected by bark beetle infestations.

While the monsoon season brings much needed moisture to the region, it also brings lightning, which sparks around 2,300 fires each year, on average, and burns 1,100 sq. km. Last year (2022), New Mexico experienced the largest wildfire on record, with the second largest just behind it.

A recent vulnerability assessment of Southwestern forests showed they are highly vulnerable to climate impacts including drought and wildfire, especially under the RCP8.5 emissions trajectory, potentially catalyzing a shift from forest to non-forest. With a lower emissions trajectory (RCP4.5), these forests are considerably less vulnerable and more resilient in the face of climate change. 

Climate change content and analyses provided by Dr. Marni Koopman.
Climate Change

Snow on the mountains near Flagstaff could disappear by the end of this century.
Photo credit: Martin Ely CC BY 2.0.

 

Climate change is already affecting the Mogollon Rim and is expected to accelerate in coming centuries. This diverse region of exceptional ecological diversity and importance experiences warmer temperatures, longer and more frequent heat waves, more drought, less snow, and lower river flows, in comparison with the historical period. Climate model projections indicate that continued warming and greater variability and likelihood of extremes can be expected. Immediate and drastic reductions in greenhouse gas emissions at the global level (RCP4.5) could still prevent many of the most extreme impacts to the Mogollon Rim, as compared to continued “business-as-usual” emissions (RCP8.5).

Some major trends for the ecoregion include the following:

  • More Drought and Extremes – While precipitation projections are highly uncertain for the Mogollon Rim, higher temperatures and more evaporation and evapotranspiration are highly certain. These changes will lead to worsening drought, regardless of precipitation. This region has not experienced the increase in storm severity seen in other parts of the nation. However, both larger storms and more severe droughts remain distinct possibilities.
  • Severe Heat – By the middle of this century, there could be over a month above 38°C and up to 2 months by the end of the century. On average, the hottest day towards the end of the century will be 4-12°C hotter than historically. Severe heat impacts natural systems as well as human health, safety, infrastructure, and agriculture.
  • Lower Streamflow and Water Quality – Snowpack could decline drastically by the second half of the 21st century, greatly affecting stream flow and water availability, as well as species adapted to upper elevations (e.g., Sky Islands, alpine areas) and cold water conditions. As precipitation shifts from snow to rain and evaporation declines, less water will be available in streams and rivers. Lower flows and warmer waters are expected to affect water quality. Cold-water fishes and other aquatic organisms are increasingly at risk.
  • Loss of Riparian Habitats – In the arid Southwest, riparian areas, wetlands, and marshes are vital for biodiversity yet highly sensitive to climate change. Loss of these habitats and degradation of water quality are significant risks.
  • Contraction of Forests and Woodlands – Forested areas are increasingly at risk from insects and disease linked to drought and heat stress. Models indicate the climate envelope for woodlands is expected to contract as grasslands become more widespread. Wildfire, disease, and other disturbances could accelerate this transition. Local areas of intact and mature forest habitat, especially with cooler or wetter microclimates, will become important refuges for species diversity.

Mogollon Rim Climate Change Risks and Impacts
The effects of climate change across the Mogollon Rim go far beyond hotter temperatures, lower snowpack, and more wildfire. A few examples of impacts include:
● Dewatering of streams and rivers during portions of each year
● Loss of important habitat for fish, wildlife, and plants
● Lower flow and warmer water, leading to higher rates of harmful algae, disease, and pollution in waterways
● More extreme and frequent severe heat, reducing opportunities for outdoor recreation
● Declines in forest-dwelling and cold-adapted species like dusky grouse (Dendragapus obscurus)
● Declines in forest health leading to shifts to non-forested landscapes
● Species shifts to higher elevations and cooler/wetter microclimates
● Tribes affected by loss of water and cultural resources, heat-related health impacts, and disruptions to agriculture

Additional risks and impacts to the ecosystems and people of the region are expected. The severity of these risks is closely linked to global greenhouse gas emissions, and can still be mitigated. Reducing not only the magnitude, but also the rate of change will allow many species to shift and adapt as climate change progresses.

In addition, Mogollon Rim ecosystems can be managed for increased resilience by reducing human-caused impacts such as deforestation, water diversion, erosion, and clearing of riparian vegetation. Large-scale restoration and protection of sensitive habitats, ecosystems, and connections will allow many species to persist across this vibrant landscape.

Climate change content and analyses provided by Dr. Marni Koopman.
    Data Resources

    Vegetation and Forests:

    Woody Plants of the Mogollon Highlands (Natural History Institute)

    Mature and Old-Growth Forests Contribute to Large-Scale Conservation Targets in the Conterminous United States (by DellaSala et al, 2022)

    Sequential Hybridization May Have Facilitated Ecological Transitions in the Southwestern Pinyon Pine Syngameon (by Buck et al., New Phytologist 2022)

    2021 Forest Health Conditions in Arizona and New Mexico (by USDA Forest Service Southwest Region 2022)

     

    Riparian Areas and Springs:

    Gila River named America’s Most Endangered River of 2019 (by American Rivers 2019)

    Effects of reintroduced beaver (Castor canadensis) on riparian bird community structure along the upper San Pedro River, southeastern Arizona and northern Sonora, Mexico (by Johnson & van Riper III 2014)

    Springs Ecosystems (by Spring Stewardship Institute)

    Mexican Wolves, Grizzly Bears, and Rewilding:

    The Saga of the Mexican Gray Wolf by D. Parsons, Rewilding Earth)

    The Mogollon Wildlife Corridor: A Big Step Toward Half Earth and Beyond (by K. Crumbo, The Rewilding Institute)

    To Infinity and Beyond: A Lone Mexican Wolf’s Search for Territory Along The Mogollon Rim (Rewilding Earth)

    Mexican Gray Wolves- The History and Recovery of a Subspecies (Gray Wolf Conservation)

    Grizzly Bears for the Southwest: History & Prospects for Grizzly Bears in Arizona, New Mexico & Colorado (by D. J. Mattson, 2022)

    Recovery of the grizzly bear at the intersection of law and science (by N. Greenwald, Frontiers in Conservation Science, 2023)

    Coconino County Wildlife Connectivity Assessment: Detailed Linkages. San Francisco Peaks – Mogollon Rim Linkage Design (Arizona Game and Fish Department)

    Southern Rockies wildlands network vision: a science-based approach to rewilding the Southern Rockies (by Miller et al., 2003)

     

    GAP Analysis:

     Gap Analysis Project (USGS)

     

    Wildfires:

    Countering false and omitted evidence of historically heterogeneous western US dry forests and mixed-severity fires (by Baker et al. 2023)

    Climate-Driven Wildfire Podcast with Dominick DellaSala (Green Root Podcast 2022)

    Implementation of National Fire Plan Treatments near the Wildland-Urban Interface in the Western United States (by Schoennagel et al., 2009)

    Have Western USA Fire Suppression and Megafire Active Management Approaches Become a Contemporary Sisyphus? (by DellaSala et. al., 2022)

    Human Ignitions on Private Lands Drive USFS Cross-Boundary Wildfire Transmission and Community Impacts in the Western US (by Downing, et al. 2022)

    Adapt to More Wildfire in Western North American Forests as Climate Changes (by Schoennagel et al. 2017)

    Mixed-severity wildfire as a driver of vegetation change in an Arizona Madrean Sky Island System, USA (by Poulos et al. 2021)

    Effects of Recent Wildfires in Piñon-Juniper Woodlands of Mesa Verde National Park, Colorado, USA (by Floyd, Romme & Hanna 2021)

    Fire Regimes and Structural Changes in Oak-Pine Forests of the Mogollon Highlands Ecoregion: Implications for Ecological Restoration (by Huffman et al., 2020)

    High-Severity Fire Corroborated in Historical Dry Forests of the Western United States: Response to Fulé et al. (by Williams & Baker, 2014)

    Countering Omitted Evidence of Variable Historical Fore (by nd Fire Regime in Western USA Dry Forests: The Low-Severity-Fire Model Rejected (by Baker et al., 2023)

    The wildland-urban interface fire problem (by Cohen, 2010)

    Land Surveys Show Regional Variability of Historical Fire Regimes and Dry Forest Structure of the Western United States (by Baker & Williams 2018)

    Human-Started Wildfires Expand the Fire Niche across the United States (by Balch et al., 2017)

     

    Climate Change:

    A Primer on Forests as Natural Climate Solutions (by DellaSala)

    Climate Change and Ecosystems of the Southwestern United States. (by Archer an Predick, Rangelands 2008)

    Declines in Pinyon Pine Cone Production Associated with Regional Warming (by Redmond, Forcella, & Barger 2012)

    Patterns and Drivers of Recent Land Cover Change on Two Trailing-Edge Forest Landscapes (by Rodman et al., 2022)

    Adapting to Climate Change on Western Public Lands: Addressing the Ecological Effects of Domestic, Wild, and Feral Ungu-lates (by Beschta et al. 2012)

      A Way Forward

      Our vision for the Mogollon Highlands ecoregion is to ADVANCE FOREST PROTECTION EFFORTS BY INTEGRATING THEM with effective wildfire planning in a changing climate. TO ACCOMPLISH THIS, FOREST SERVICE FUEL REDUCTION EFFORTS NEED TO FOCUS TREATMENTS CLOSEST TO HOMES AND REMOVE LESS BIOMASS FROM THE FOREST THAT ARE BEING OVERLY THINNED AND TOO FREQUENTLY BURNED. We envision supporting dynamic natural ECOSYSTEMS INCLUDING mature and old growth forests, springs, RIPARIAN AREAS, and rivers. Our vision calls for RECONNECTING AND REWILDING LANDSCAPES FOR FOCAL SPECIES LIKE WOLVES AND FOR REINTRODUCING EXTIRPATED SPECIES LIKE GRIZZLY BEARS WHILE PROVIDING FOR plant dispersal and animal migration IN A RAPIDLY CHANGING CLIMATE. 

      Help restore degraded lands and manage wildland fires safely!

      Help restore degraded lands and manage wildland fires safely!