Our Ranchlands Land Lab

Diablo Trust works with researchers and scientists to provide access to working lands to conduct cutting-edge research that helps our community better understand the interconnected nature of ranchlands, wildlife, and people

NAU Integrated Monitoring for Sustainability

Since 1987 researchers at Northern Arizona University under the direction of Dr. Tom Sisk have been conducting an experiment studying the effects of livestock on grassland ecosystems. The researchers collaborate with ranchers in moving cattle among replicated 2.5-acre study plots.

Results from this effort are providing important insight into the complex effects of grazing, and climate change. Integrated Monitoring for Sustainability (IMfoS) emerged from a collaborative process among Diablo Trust, agencies, and Northern Arizona University and Prescott College.

Using an integrated monitoring framework, the Holistic Ecosystem Health Indicator (HEHI), this project assesses and monitors the sustainability of the Diablo Trust ranches.

Objectives include:

  • development of cost-effective sampling protocols for the ecological and social indicators

  • transferring knowledge through hands-on monitoring and training workshops;

  • field testing of HEHI as a monitoring tool for Community-based Collaboratives

The implementation of HEHI combines data from existing monitoring efforts and enhances the Diablo Trust’s adaptive management through improved transparency, stakeholder facilitation, and increased learning.

Forage Resource Study Group

The Forage Research Study Group (FRSG) is the longest consistent utilization monitoring program in Arizona, FRSG brings together the USFS, ASLD, Arizona Game and Fish Department (AZGFD,) and Diablo Trust ranches to monitor plots that were designed in the 1940s. The Group uses rain gauges, utilization cages, geospatial analysis, photo plots, condition and trend transects, and wildlife censuses.

Range Management Plan

The Diablo Trust Range Management Plan for the Diablo Trust ranches, prepared in collaboration with agencies includes provisions for monitoring a variety of on-the-ground projects for land and wildlife improvement.

Past Research

Reframing the Grazing Debate: Evaluating Ecological Sustainability and Bioregional Food
(Matthew R. Loeser, Thomas D. Sisk, Timothy E. Crews, Kurt Olsen, Craig Moran and
Christina Hudenko)


The semi-arid grasslands of the Colorado Plateau are productive, diverse, and extensive
ecosystems. The majority of these ecosystems have been altered by human land use, primarily
through the grazing of domestic livestock, yielding a plethora of environmental and social
consequences that are tightly interconnected. From an agroecological perspective, untangling
these issues requires both an understanding of the role of livestock grazing in bioregional food
production and the effect of that grazing on ecological sustainability. To address the former, we
discuss the importance of cattle ranching as a bioregional food source, including estimates of
meat production and water use in Arizona. To address the latter, we present data from a long-
term project addressing changes in native plant community composition, under a range of
alternative livestock management strategies. Our study site near Flagstaff, AZ includes four
different management treatments: (1) conventional low-intensity, long-duration grazing
rotations; (2) high-intensity, short-duration rotations; (3) very high-impact, very short-duration
grazing (to simulate herd impact); and, (4) livestock exclosure. Preliminary results suggest
belowground properties are responding more quickly to grazing treatments than aboveground
properties. Particular response variables, such as cyanobacteria and diatoms, show a marked
short-term response to very high-impact, short-duration grazing, but long-term implications are
as yet unknown.

Defoliation Increased Above-Ground Productivity in a Semi-Arid Grassland
(Matthew R. Loeser, Timothy E. Crews, and Thomas D. Sisk)


In light of the continuing debate regarding overcompensation we studied the responses
of above-ground biomass in a high-elevation, semi-arid grassland to defoliation, defoliation
history, and livestock grazing. The above-ground annual net primary productivity (ANPP) was
measured over 2 years in one-hundred twenty, 1-M2 plots that were exposed to single- and
multi-year defoliation and grazing treatments. Plant communities showed an average increase
in ANPP of 31%-45% due to a single defoliation event. The most conservative estimate of
average ANPP of defoliated subplots was 29.4 g m-2 greater than the non-defoliated controls.

A history of defoliation, due to clipping or grazing, lessened the magnitude of the compensatory
response, but above-ground overcompensation of biomass was still observed, ranging on
average from 17% to 26%. One dominant species, squirreltail grass [Elymus elymoides (Raf.)
Swezeyi], accounted for nearly one-third of the community-level increases in ANPP. In contrast
to above-ground patterns, below-ground root production of squirreltail did not increase in
response to defoliation events. These results suggest that the above-ground production of high-
elevation, semi-arid grasslands in the American Southwest may be temporarily increased
through certain grazing events, and may help explain shifts in species dominance in grasslands
exposed to long-term grazing by livestock.

Plant Community Responses to Livestock Grazing: an Assessment of Alternative
Management Practices in a Semiarid Grassland

(Matthew R. Loeser, Thomas D. Sisk, and Timothy E. Crews)


One of the most prevalent land-use practices in the American Southwest, and one of the
most contentious issues among land-use policymakers, is the grazing of domestic livestock. In
an effort to contribute scientific understanding to this debate, we have designed experiments
comparing the effects of alternative grazing regimes on plant communities. In a semiarid
grassland of northern Arizona, we have implemented a replicated study of four treatments: (1)
low-intensity, long-duration grazing rotations; (2) high-intensity, short-duration rotations
(Holistic Resource Management-style grazing); (3) very high intensity, short duration grazing (to
simulate herd impact); and (4) livestock exclosure. Beginning in 1997, we conducted annual
surveys of the plant communities with Modified-Whittaker plots. Preliminary results suggest
that interannual variability affecting all study plots is high, and that these alternative
management strategies do not have dramatic short-term effects on the plant community.

Comparisons of native and exotic species richness, as well as ground cover of grasses and forbs,
showed no consistent pattern due to treatment over a 3-year period. Our results suggest that
the effects of alternative livestock management styles in the semiarid grasslands studied are
modest, at least in the short-term, and that future plant monitoring programs would greatly
benefit from a multiscale sampling design.

Vegetation Cover and Forb Responses to Cattle Exclusion: Implications for Pronghorn
(Matthew R. Loeser, Sharon D. Mezulis, Thomas D. Sisk, and Tad C. Theimer)


Cattle grazing is often implicated as a factor that reduces vegetative cover and the
abundance of important forage plants for wildlife. Recent declines in northern Arizona
populations of pronghorn (Antilocapra americana Ord) have focused public and scientific
attention on the factors contributing to low fawn recruitment and the potential benefits of
cattle removal. To further understand the effects of cattle grazing, we studied the potential
hiding cover provided by standing live and dead herbaceous matter as well as forb richness and
canopy cover following 5 years of cattle removal. Cattle removal increased horizontal hiding
cover by 8% at a distance of 5 m (P = 0.025), but had no statistically significant effect on the
potential hiding cover at distances of 10 m (P = 0.105) or 25 m (P 0.746). Forb species richness
was 16% lower in exclosures than in an adjacent grazed pasture in 2001 (P = 0.036), but no
differences were observed in 2002 (P = 0.636). The canopy cover of forbs was generally
unaffected by cattle removal. These results suggest that curtailing or removing cattle is unlikely,
by itself, to lead to rapid improvements in the hiding cover or forb availability for pronghorn on
similar rangelands in northern Arizona. In this region, where immediate improvements in fawn
survival and recruitment are important to population persistence, additional management
actions should be considered.

Impact of Grazing Intensity during Drought in an Arizona Grassland
(Matthew R. Loeser, Thomas D. Sisk, and Timothy E Crews)


The ecological benefits of changing cattle grazing practices in the western United States
remain controversial, due in part to a lack of experimentation. In 1997 we initiated an
experimental study of two rangeland alternatives, cattle removal and high-impact grazing, and
compared grassland community responses with those with more conventional, moderate
grazing practices. The study was conducted in a high-elevation, semiarid grassland near
Flagstaff, Arizona (U.S.A.). We conducted annual plant surveys of modified Whittaker plots for 8
years and examined plant composition shifts among treatments and years. High-impact grazing
had strong directional effects that led to a decline in perennial forb cover and an increase in
annual plants, particularly the exotic cheatgrass (Bromus tectorum L.). A twofold increase in
plant cover by exotic species followed a severe drought in the sixth year of the study, and this
increase was greatest in the high-impact grazing plots, where native cover declined by one-half.

Cattle removal resulted in little increase in native plant cover and reduced plant species
richness relative to the moderate grazing control. Our results suggest that some intermediate
level of cattle grazing may maintain greater levels of native plant diversity than the alternatives
of cattle removal or high-density, short-duration grazing practices. Furthermore, episodic
drought interacts with cattle grazing, leading to infrequent, but biologically important shifts in
plant communities. Our results demonstrate the importance of climatic variation in determining
ecological effects of grazing practices, and we recommend improving conservation efforts in
arid rangelands by developing management plans that anticipate this variation.

A Framework to Evaluate Ecological and Social Outcomes of Collaborative Management:
Lessons from Implementation with a Northern Arizona Collaborative Group

(Tischa A. Muñoz-Erickson, Bernardo Aguilar-González, Matthew R. Loeser, and Thomas
D. Sisk)


As collaborative groups gain popularity as an alternative means for addressing conflict over management of public lands, the need for methods to evaluate their effectiveness in achieving ecological and social goals increases. However, frameworks that examine both effectiveness of the collaborative process and its outcomes are poorly developed or altogether lacking. This paper presents and evaluates the utility of the holistic ecosystem health indicator (HEHI), a framework that integrates multiple ecological and socioeconomic criteria to evaluate management effectiveness of collaborative processes. Through the development and application of the HEHI to a collaborative in northern Arizona, the Diablo Trust, we present the opportunities and challenges in using this framework to evaluate the ecological and social outcomes of collaborative adaptive management. Baseline results from the first application of the HEHI are presented as an illustration of its potential as a co-adaptive management tool. We discuss lessons learned from the process of selecting indicators and potential issues to their long-term implementation. Finally, we provide recommendations for applying this framework to monitoring and adaptive management in the context of collaborative management.

Identifying Indicators of Ecosystem Health for a Semiarid Ecosystem: A Conceptual Approach
(Tischa A. Muñoz-Erickson, Matthew R. Loeser, and Berardo J. Aguilar-González)


Managers of public and private lands face a challenging dilemma. With finite and often
limited resources, these individuals are being asked to manage for sustainability, but the definition of sustainability is typically user-defined, and ultimately vague. In cases where so-called objective approaches have been employed, the emphasis has been on ecological science that often ignores both the role and effects of humans in managed ecosystems (Liu 2001). These ecosystems are subjected to a high degree of environmental variability and anthropogenic disturbance; thus, assessing their condition must reflect their inherent complexity (Haskell et al. 1992). For example, in agricultural ecosystems, there has been a growing recognition that ecology needs to be integrated with economics to achieve long-term sustainability (Aguilar 1999; Crews et al. 1991). Therefore, achieving sustainability in managed ecosystems requires an expanded approach that hybridizes the “hard sciences” that develop an understanding of the structure and function of ecosystems, with the “soft sciences” that focus on social and economic understanding of human communities (Allen and Hoekstra 1992).

The appropriate management of semiarid ecosystems has generated substantial debate because these areas are typically rich in biological diversity and human use. The landscapes of the southern Colorado Plateau have been subjected to a broad array of land uses since the settlement of European-Americans, including, but not limited to urban development, crop agriculture, livestock grazing, recreation, off-road vehicles, and total preservation (to the point of preventing natural events such as fire and flooding). Perhaps the most pervasive land-use practice on semiarid ecosystems has been the grazing of domestic livestock and its associated land-management practices (Fleischner 1994). Issues like livestock grazing remain politically contentious, not necessarily because we lack sufficient ecological knowledge, but more likely because we lack adequate integration of the ecological and social effects of choosing a grazing policy (Sisk et al. 1999; Loeser et al. 2001; Jemison and Raish 2000). Given the highly political atmosphere and uncertainty in managing semiarid ecosystems, managers need an analysis that combines general theoretical information on rangeland vegetation dynamics, site-specific parameters applied to a real context, and implications relevant to the scale and dimension of the “management space” they are working in (Archer et al. 1999). In this paper we employ the concept of ecosystem health and integrated indicators as a method to monitor and evaluate the effects of management decisions. In the first section of the article we define ecosystem health for the system under study through the integration of existing scientific theory on ecosystem health and rangeland vegetation dynamics (Part I, Figure 1). The desired dynamics are defined with site-specific management objectives determined through a stakeholder approach, as exemplified with a case study of a local range-management collaborative group, the Diablo Trust, located in Flagstaff, AZ.

Linking Ecosystem Health Indicators and Collaborative Management and Systematic Framework to Evaluate Ecological and Social Outcomes
(Tischa A. Muñoz-Erickson, Bernardo Aguilar-González and Thomas D. Sisk)


Collaborative management has gained popularity across the United States as a means of
addressing the sustainability of mixed-ownership landscapes and resolving persistent conflicts in public lands management. At the same time, it has generated skepticism because its ecological and social outcomes are seldom measured. Evaluating the success of collaborative efforts is difficult because frameworks to assess on-the-ground outcomes are poorly developed or altogether lacking. Ecosystem health indicators are valuable tools for evaluating site-specific outcomes of collaboration based on the effects of collaboration on ecological and socioeconomic conditions. We present the holistic ecosystem health indicator, a promising framework for evaluating the outcomes of collaborative processes, which uses ecological, social, and interactive indicators to monitor conditions through time. Finally, we draw upon our experience working with the Diablo Trust, a community-based collaborative group in northern Arizona, USA, to illustrate the development of an indicator selection model generated through a stakeholder-driven process.

Plant Production Responses to Precipitation Differ Along an Elevation Gradient and Are Enhanced Under Extremes

(Seth M. Munson, Erin L. Bunting, John B. Bradford, Bradley J. Butterfield, and Jennifer R. Gremer)


The sensitivity of plant production to precipitation underlies the functioning of ecosystems. Studies that relate long-term mean annual precipitation and production across multiple sites (spatial relationship) or examine interannual linkages within a site (temporal relationship) can reveal biophysical controls over ecosystem function but have limited ability to infer responses to extreme changes in precipitation that may become more common under climate change. To overcome limitations of using a single approach, we integrated satellite- and ground-based estimates of production with a standardized, multi-site precipitation manipulation experiment across a grassland elevation gradient in the southwestern USA. The responsiveness of production to changes in precipitation followed the order: temporal (0.06–0.13 g m-2 mm-1) < spatial (0.21 g m-2 mm-1) < experimental relationship (0.25–0.42 g m-2 mm-1), suggesting that spatial and temporal relationships determined with satellite- and ground-based estimates cannot be extrapolated to determine the effect of extreme events. A strong production response to differences in mean annual precipitation across sites reinforces a regional control of water availability. Interannual sensitivity to precipitation was strongest at the low elevation grasslands, and the high elevation mixed conifer meadow had a large reduction in production in a drought year. Extreme experimental drought strongly reduced production in low elevation grasslands, but water addition had mixed effects. High elevation meadows were insensitive to both extreme drought and water addition. Our results highlight the importance of accounting for extreme climate regimes and site-level factors when scaling climate change effects up to regional and global scales.

Abiotic and Biotic Mediation of Grazing Impacts on Soil Carbon in Northern Arizona

(Megan Marie Deane McKenna)


Soil, the largest terrestrial carbon reservoir, has the ability to sequester carbon, however numerous variables influence its storage potential. Livestock management practices, precipitation, plant species composition, and soil parent material may all influence the potential for carbon to be stored in the soil. There is little empirical evidence measuring these effects in arid and semi-arid environments which motivated this study to sample across the Diablo Trust in northern Arizona. Stratified random sites were selected based on the locations of fence-lines or grazing exclosures that have excluded livestock for at least 20 years. Soil samples were collected from grazed and adjacent ungrazed sides of the fences across five distinct soil series and along a precipitation gradient ranging from 230 mm – 623 mm at the surface (0-5 cm) and subsurface (20-25 cm). The sites were measured for soil texture, precipitation, plant community composition, root biomass, soil organic carbon, and soil inorganic carbon. Results from the general linear models and the structural equation model found that the abiotic factors of precipitation and soil texture were the main drivers in soil organic and inorganic carbon. Grazing did not have a significant direct effect on soil organic or inorganic carbon, although there were significantly more C4 grasses under the grazed treatments. Surprisingly, roots, especially C4 roots, had a greater effect on soil inorganic carbon than organic carbon. More research is needed to better understand the mechanisms driving this interaction but could be crucial to understand if this drives more carbon to be released into the atmosphere in semi-arid and arid environments. Overall, the results from this study show that the abiotic factors of soil texture and precipitation were the main drivers in soil organic and inorganic carbon across this semi-arid rangeland. This may be explained through the theoretical framework provided by the state-and-transition model which incorporates both equilibrium and non-equilibrium models. Arid and semi-arid environments have more stochastic rainfall patterns compared to mesic environments, driving net primary production, which increases with timely precipitation. Along the continuum of the state-and-transition model, semi-arid rangelands fall more along the non-equilibrium systems. If the non-equilibrium model explains more of the ecological dynamics within system in this semi-arid rangeland, then predictable sequestration of carbon is complex through management and it may not be appropriate to include management practices within protocols in the voluntary carbon market. More research is needed to better understand grazing’s impact on soil carbon storage across various precipitation gradients. The research from this study shows that grazing had a minimal impact on soil carbon storage across a landscape scale and that there are biotic interactions with inorganic carbon that can no longer be ignored.

Diablo Trust Pinon-Juniper Restoration Sites: Restoring Structure to Woodlands and Savannas

(Andrew Gascho Landis and John Duff Bailey)


Pinon-juniper restoration sites are being implemented in northern Arizona on lands managed by the Diablo Trust that have experienced increased pinon and juniper densities. Such land managers want to restore basic ecosystem structure and function to their lands in a way that preserves their livelihoods and open space in the region. The first objective of this project was to create reference conditions by reconstructing age structure and spatial arrangement to 1860, prior to livestock grazing, across three soil types. Stand reconstruction using stem mapping and ring counts revealed pulses of juniper establishment between 1860 and 1880 on both basalt and sandstone-derived soils. Limestone-derived soil showed no increase during this time period, but rather steady increase in tree density since approximately 1700. Juniper trees in 1860 across all soil types were found in clumps of a minimum radius of 15 m. Presettlement diameter distributions and basal area were reconstructed and used to develop structure control (e.g., BDq) prescriptions to best approximate stand conditions of both pinon-juniper savannas and woodlands. After these appropriate density and distributions were determined, the next phase of this project is to test restoration methods, which include burning, seeding, and slash treatments (leave tree, pile, lop and scatter) to determine which treatment fosters greatest understory plant response.

The Fight for the West: A Political Ecology of Land Use Conflicts in Arizona

(Mette J. Brogden and James B. Greenberg)


The commoditization of natural resources in a global economic system and the territorialization practices of nation-states present formidable challenges to the sustainable use of natural resources. Likewise, certain environmental problems such as growth management and residential sprawl have proved intractable to our existing political processes. This case study of grazing and growth conflicts in Arizona demonstrates that intractable environmental problems may actually be emergent properties of complex systems, requiring new political approaches that foster collaboration and knowledge sharing between disputing stakeholders. One such collaboration in Arizona revealed that attempts to remove grazing from Arizona landscapes could actually be to the detriment of biodiversity, contrary to the expectations of grazing critics

Collaborative Stewardship of Arizona’s Rangelands

(Maria E. Fernández-Giménez, Sonya Le Febre, Alex Conley and Amy Tendick)


Collaboration has become a buzzword in natural resource management. But what does it mean, and how is it affecting what happens on the ground? To answer these questions, we studied collaborative partnerships on Arizona rangelands by 1) contacting resource management professionals to identify as many collaborative partnerships as we could and 2) surveying a selected subset of these collaboratives by telephone. Our objectives were to determine the extent of collaboration on Arizona rangelands, identifying the types of collaboratives active in the state, and describe the roles they are playing in the management of Arizona’s rangelands. Although we recognized that collaboration is a growing trend in the West, we were stunned when we identified > 100 collaborative partnerships on rangelands alone. We found that Arizona collaboratives are diverse in their purposes and participants and are involved in many facets of rangeland management. They play a significant role in many areas of natural resource management, especially monitoring. However, most groups view their major achievements (and challenges), as organizational development and community capacity building.

Reconstruction of Age Structure and Spatial Arrangement of Piñon-Juniper Woodlands and Savannas of Anderson Mesa, Northern Arizona

(Andrew Gascho Landis and John Duff Bailey)


We examined age structure and spatial arrangement of piñon–juniper woodlands and savannas on six plots distributed across three different soil types in northern Arizona. These stands, as typical of many others in piñon–juniper ecosystems, have experienced increases in tree densities since the arrival of European settlers. The goal of this study was to reconstruct stand conditions in 1860, prior to livestock grazing, using stem-mapping to determine tree arrangement and tree-ring analysis to examine age structure and density. Ripley's K(t), Ripley's K12(t), and Moran's I were used to analyze nearest neighbor distances, spatial association, and spatial autocorrelation, respectively. All sites have long term presence of juniper and piñon trees, with a pulse of establishment and survival occurring between 1860 and 1880 on basalt- and sandstone-derived soils. In contrast, limestone-derived soil had no pulse of tree establishment in 1860, but rather a steady increase in tree establishment since ca. 1700. Spatial arrangement of juniper trees in 1860 showed strong clumping patterns from a minimum distance of 15 m to all spatial scales. Piñon pine varied in spatial arrangement from clumping at all spatial scales to random at all spatial scales. Positive spatial autocorrelation was determined for age of juniper trees to a minimum distance of 21 m in current stand conditions, in contrast to no strong trends of spatial autocorrelation in 1860. By comparing the age structure and spatial results for the forest reconstruction of 1860 to current conditions, we were able to show variation among soil types in nurse tree association between piñon and juniper trees and unable to support the density dependent mortality hypothesis for these sites. Presettlement (1860) diameter distributions and basal areas can be used to develop structure control (BDq) prescriptions unique to each soil type to restore either savanna or woodlands condition. However, identifying one blanket prescription for tree reduction in piñon–juniper ecosystems of the southwestern United States, or even the Anderson Mesa landscape, would reduce the range of variability present in the form of woodlands and savannas.

Distributed Field Trial Network for Dryland Restoration -  Restoration Assessment and Monitoring Program for the Southwest (RAMPS)

(Molly McCormick, Seth Munson, Brad Butterfield, and Elise Gornish)


Researchers at USGS and NAU are teaming up to develop a network of restoration field trial sites covering the Colorado Plateau, Sonoran, Chihuahuan, and Mojave Deserts. The field trial network is a collaborative effort between scientists and land managers that systematically tests restoration techniques. This network will test the suitability of a broad range of species and seed mixes for restoration, coupled with a suite of restoration treatments to promote plant establishment and growth including ground modifications (e.g., soil amendments or types of mulch), seed coating technologies, seeding methods, seasonality of planting, successional planting, and inputs like herbicide treatments, fertilizer, and supplemental irrigation.The distributed field trial network will:(1) Provide critical information to land managers on methods to improve restoration outcomes; (2) Assess the ecosystem services (e.g., forage, erosion control, soil fertility, pollination) provided by different species and communities, rather than just the growth and establishment of individual species; and (3) Be co-located with existing common gardens or other ongoing experiments, whenever possible, to complement existing knowledge on development of native plant materials and minimize costs of developing new infrastructure.