← Back to Speciesspecies

Artemisia

Common names: sagebrush

Taxonomy: Plantae > Tracheophyta > Magnoliopsida > Asterales > Asteraceae

Roles: habitat component, study subject

ITIS TSN: 35431

External: RMBL Collections · iNaturalist · iDigBio · GenBank

Papers: 134 | Mentions: 194

Local Knowledge Graph (Top 81 entities)

View in full graph →

Loading graph...

Publications (134)

article

Depth of nutrient uptake by deep-rooted plants is regulated by water availability

2026PNASRole: text_match

article

Experimental warming decouples plant-fungal symbiont interactions and leads to a more conservative ecosystem

2026PNASRole: text_match

article

Fitness costs and benefits of a non-native floral resource for subalpine solitary bees

2025OikosRole: text_match

student_paper

Associations Between Deer Browse and Aphid Colonization in a Long-Term Monitoring Study of Liguisticum porteri

2024Role: text_match

student_paper

Getting to the Root of It: Effects of Castilleja Root Hemiparasitism on Plant Community Structure and Function

2024Role: text_match

student_paper

Indirect effect of black bears on sunflowers in nitrogen-polluted and pristine steppe

2024Role: text_match

article

Scaling Landscape Fire History: Wildfires Not Historically Frequent in the Main Population of Threatened Gunnison Sage-Grouse

2024FireRole: text_match

article

Climate lags and genetics determine phenology in quaking aspen (Populus tremuloides)

Documents (20)

technical report

1980

technical report

A Classification of the Riparian Vegetation of the Gunnison River Basin, Colorado

wildlife survey

An Illustrated Guide to the Proposed Threatened and Endangered Plant Species in Colorado

environmental assessment

Appendix 2 List of Designated Colorado Natural Areas, List of Registered Colorado Natural Areas, List of Identified Colorado Natural Areas

management plan

Candidate Conservation Agreement With Assurances for Gunnison Sage-grouse (Centrocerucus minimus) between the Colorado Division of Wildlife and the U.S. Fish and Wildlife Service

technical report

Colorado Ranch Management School (Part 2)

technical report

Colorado Ranch Management School (Part 5)

technical report

Department Of Energy Compliance With Floodplain – Wetlands Environmental Review Requirements

environmental assessment

Draft Environmental Impact Statement

environmental assessment

Draft: Environmental Assessment of the Proposed Remedial Action at the Gunnison Uranium Mill Tailings Site

Show 10 more documents

Co-occurring Species

2023New PhytologistRole: text_match

article

Demographic responses of hybridizing cinquefoils to changing climate in the Colorado Rocky Mountains

2023Ecology and EvolutionRole: text_match

thesis

Effects of microclimate, dispersal, species interactions, and environmental stochasticity on demography

2023Role: text_match

student_paper

Effects of warming, dominant species removal, and accelerated snowmelt on aboveground plant traits in the Colorado Rocky Mountains

2023Role: text_match

article

Herbivory damage but not plant disease under experimental warming is dependent on weather for three subalpine grass species

2023Journal of Animal EcologyRole: text_match

article

Historical fire regimes and contemporary fire effects within sagebrush habitats of Gunnison Sage‐grouse

2023EcosphereRole: text_match

chapter

Sage-Grouse

2023Role: habitat component

article

Phenotypic plasticity and selection on leaf traits in response to snowmelt timing and summer precipitation

2022New PhytologistRole: text_match

thesis

Revealing the direct and indirect effects of climate change on soil nutrient dynamics and forage resources in mountain ecosystems

2022Role: text_match

student_paper

The Effect of Climate Change on Soil Organic Carbon over an Elevational Gradient

2022Role: text_match

article

Changes in hunting season regulations (1870s–2019) reduce harvest exposure on greater and Gunnison sage-grouse

2021PLOS ONERole: text_match

article

Chronic, low-level nitrogen deposition enhances abundances of ant-protected herbivores inhabiting an imperiled foundation species

2021Acta OecologicaRole: text_match

article

Cytotype and genotype predict mortality and recruitment in Colorado quaking aspen ( Populus tremuloides )

2021Ecological ApplicationsRole: text_match

thesis

Effects of early snowmelt on plant phenophase timing and duration across an elevation gradient

2021Role: text_match

article

Snow melt timing acts independently and in conjunction with temperature accumulation to drive subalpine plant phenology

2021Global Change BiologyRole: text_match

article

Bee phenology is predicted by climatic variation and functional traits

2020Ecology LettersRole: text_match

article

Low predictability of energy balance traits and leaf temperature metrics in desert, montane and alpine plant communities

2020Functional EcologyRole: text_match

article

Remote Sensing-Informed Zonation for Understanding Snow, Plant and Soil Moisture Dynamics within a Mountain Ecosystem

2020Remote SensingRole: habitat component

article

Remote sensing of ploidy level in quaking aspen (Populus tremuloides Michx.)

2020Journal of EcologyRole: text_match

article

The Snowmelt Niche Differentiates Three Microbial Life Strategies That Influence Soil Nitrogen Availability During and After Winter

2020Frontiers in Microbiology. doi 10.3389/fmicb.2020.00871Role: text_match

article

Comparing predictive measures and model functions for estimating plant biomass: lessons from a sagebrush–rabbitbrush community

2019Plant EcologyRole: text_match

article

Depth- and time-resolved distributions of snowmelt-driven hillslope subsurface flow and transport and their contributions to surface waters.

2019Water Resources ResearchRole: text_match

student_paper

Identifying the Impact of Biotic Interactions on Meadow Species Distributions in Sagebrush and Bunchgrass Dominated Systems

2019Role: text_match

article

Investigating Microtopographic and Soil Controls on a Mountainous Meadow Plant Community Using High-Resolution Remote Sensing and Surface Geophysical Data

2019Journal of Geophysical Research: BiogeosciencesRole: text_match

article

Parasitism modifies the direct effects of warming on a hemiparasite and its host

2019PLOS ONERole: text_match

article

A model for leaf temperature decoupling from air temperature

2018Agricultural and Forest MeteorologyRole: text_match

article

Chemotypic variation in oshá (Ligusticum porteri) in Colorado, USA

2018J Appl. Res. Med. Aromat. PlantsRole: text_match

article

Climate Warming Drives Local Extinction: Evidence from Observation and Experimentation

2018ScienceAdvancesRole: text_match

student_paper

First-order controls of soil and leaf moisture

2018Role: text_match

other

Rocky Mountain Biological Lab. Ecology of Place: Making Ecology and Evolutionary Biology spatially explicit

2018Mountain ViewsRole: study subject

article

Short-term, low-level nitrogen deposition dampens a trophic cascade between bears and plants

2018Ecology and EvolutionRole: text_match

student_paper

The Effect of Climate Change on Plant Communities in the Rocky Mountains: How floral traits differ along an elevational gradient and in reciprocally transplanted communities

2018Role: text_match

student_paper

The impacts of early snowmelt and summer precipitation on the physiology and leaf morphology of Ipomopsis aggregata

2018Role: text_match

article

Integrating viability and fecundity selection to illuminate the adaptive nature of genetic clines

2017Evolution LettersRole: text_match

article

Intraspecific variation in traits reduces ability of trait-based models to predict community structure

2017Journal of Vegetation ScienceRole: text_match

article

Effects of climate change on phenologies and distributions of bumble bees and the plants they visit

2016EcosphereRole: text_match

thesis

Productivity of Montane Meadows in a Warming World: Evidence from an Elevation Gradient and a Warming Experiment

2016Role: text_match

student_paper

The Changing Floral Color Landscape Across an Alpine Elevation Gradient

2016Role: text_match

student_paper

The Effects of Ants on Ecosystem Dynamics: Investigating the Ecological Influence of Ant Nests in the Rocky Mountains

2016Role: text_match

article

Convergent ecosystem responses to 23-year ambient and manipulated warming link advancing snowmelt and shrub encroachment to transient and long-term climateâ€“soil carbon feedback

2015Global Change BiologyRole: text_match

student_paper

Elevational and temporal variation in Ipomopsis floral and vegetative traits.

2015Role: text_match

student_paper

Geographic variation in flowering phenology in Boechera stricta: testing for adaptive response to climate across the species range

2015Role: text_match

article

Nest Success of Gunnison Sage-Grouse in Colorado, USA

2015PLOS ONERole: text_match

article

Plasticity in functional traits in the context of climate change: A case study of the subalpine forb Boechera stricta (Brassicaceae)

2015Global Change BiologyRole: text_match

student_paper

Aboveground and belowground traits of dominant and sub-dominant species along an elevational gradient.

2014Role: text_match

article

Changes in ant community composition caused by 20 years of experimental warming vs.13 years of natural climate shift

2014EcosphereRole: text_match

article

Coyotes, deer, and wildflowers: diverse evidence points to a trophic cascade

2014NaturwissenschaftenRole: text_match

article

Human activity affects the perception of risk by mule deer

2014Current ZoologyRole: text_match

article

Inferring climate from angiosperm leaf venation networks

2014New PhytologistRole: text_match

student_paper

Plant Successional Changes Over 67 Years on the Gothic Earthflow.

2014Role: text_match

student_paper

Pocket gopher activity across elevation gradients.

2014Role: text_match

article

Responses of high-altitude graminoids and fungal fungi to 20 years of experimental warming

2014EcologyRole: text_match

article

The historical distribution of Gunnison Sage-Grouse in Colorado

2014The Wilson Journal of OrnithologyRole: text_match

student_paper

Chemical camouflage and the consequences of changing host plants in a treehopper-ant mutualism

2013Role: text_match

student_paper

Effects of experimental warming on plant traits of subalpine wildflower species of Gothic, CO

2013Role: text_match

chapter

Phenology: An Integrative Environmental Science

2013Role: text_match

student_paper

Scale of plasticity and local adaptation in Boechera stricta along an altitudinal gradient

2013Role: text_match

student_paper

Won't you be my neighbor: neighborhood effect influences mycorrhizal and endophyte colonization

2013Role: text_match

article

Phenotypic plasticity and adaptive evolution contribute to advancing flowering phenology in response to climate change

2012Proceedings of the Royal Society of London B: Biological SciencesRole: text_match

student_paper

Real and experimental ecosystem warming: interacting effects on snowmelt, plant community composition and carbon storage in a Rocky Mountain subalpine meadow

2012Role: text_match

article

The effect of ants on the population dynamics of a protective symbiont of aphids, Hamiltonella defensa

2012Annals of Entomological Society of AmericaRole: text_match

thesis

The structure and function of subalpine ecosystems in the face of climate change

2012Role: text_match

student_paper

A comparative study of plant species diversity on three historic mining sites

2011Role: text_match

student_paper

Causes of predation intensity in an ant/aphid mutualist system

2011Role: text_match

student_paper

Effects of species composition change under experimental warming on soil microclimate in a montane meadow

2011Role: text_match

student_paper

Impact of mound-building ants on ecosystem properties create islands of fertility in alpine meadows

2011Role: text_match

student_paper

Spatial distribution of mule deer (Odocoileus hemionus): Effects of plant palatability and habitat structure

2011Role: text_match

thesis

The effect of ants on the population dynamics of Hamiltonella defensa a protective symbiont of aphids

2011Role: text_match

student_paper

The effects of hemiparasitism by Castilleja spp on community structure in alpine ecosystems

2011Role: text_match

student_paper

Fitness costs of the aphid endosymbiont, Hamiltonella defensa

2010Role: text_match

student_paper

Proximity to mountain big sagebrush (Artemisia tridentata var. vaseyana) negatively affects performance of two shallow rooted forbs, low larkspur (Delphinium nuttallianum, syn. D. nelsonii) and aspen fleabane (Erigeron speciousus).

2010Role: text_match

student_paper

Testing the predictions of the Maximum Information Entropy Theory for abundance and energy distributions on the Gothic earthflow

2010Role: text_match

student_paper

A test of species-area theory on a high disturbance area of the Gothic earthflow

2009Role: text_match

article

Controls on radial growth of mountain big sagebrush and implications for climate change

2009Western North American NaturalistRole: text_match

article

Effect of Imazapic on Cheatgrass and Native Plants in Wyoming Big Sagebrush Restoration for Gunnison Sage-grouse

2009Natural Areas JournalRole: text_match

student_paper

Effects of water addition on above- and below-ground processes in montane meadows

2009Role: text_match

student_paper

Plant community composition with respect to species richness along an altitudinal gradient in gunnison county, co

2009Role: text_match

student_paper

Possible influence of altitude, geographical distance between sites and annual precipitation rates on species richness

2009Role: text_match

student_paper

Reciprocal effects among the ant Formica obscuripes and the asters Chrysothamnus viscidiflorus and Artemisia tridentata

2009Role: text_match

student_paper

Species richness along an elevational gradient

2009Role: text_match

article

Variation in the impact of climate change on flowering phenology and abundance: an examination of two pairs of closely related wildflower species

2009American Journal of BotanyRole: text_match

article

Effects of climate change on phenology, frost damage, and floral abundance of montane wildflowers

2008EcologyRole: text_match

student_paper

Effects of water addition on below- and above-ground carbon processes across a montane elevational gradient

2008Role: text_match

article

Insect herbivore stoichiometry: the relative importance of host plants and ant mutualists

2008Ecological EntomologyRole: text_match

article

Lifetime fitness in two generations of Ipomopsis hybrids

2008EvolutionRole: text_match

student_paper

Changing distributions, changing climate: Using Bombus as an indicator of global warming near Crested Butte, Colorado

2007Role: text_match

student_paper

Climate change and anti-herbivory resistance communication in Artemisia tridentata

2007Role: text_match

student_paper

Devising an ageing technique for Artemisia tridentata ssp. vaseyana near Crested Butte, Colorado

2007Role: text_match

article

Effects of long-term experimental warming on aphid density in the field

2007Journal of the Kansas Entomological SocietyRole: text_match

article

Reproductive and physiological responses to simulated climate warming for four subalpine species

2007New PhytologistRole: text_match

student_paper

The effect of ants on membracid nymph size and instar

2007Role: text_match

student_paper

Assessing Two Plant Leaf Functional Traits across a Temperature Gradient

2006Role: text_match

article

Bottom-up mediation of an ant-membracid mutualism: effects from different host plants

2006Evolutionary EcologyRole: text_match

other

Shifts in plant dominance control short and long-term carbon-cycle responses to widespread drought

2006Role: text_match

student_paper

The timing of the ant-effect on nymph size and survivorship in an ant-treehopper mutualism

2006Role: text_match

article

Ecophysiology of first and second generation hybrids in a natural plant hybrid zone

2005OecologiaRole: text_match

student_paper

Effects of climate change on growth and seedling establishment of young lodgepole pine

2005Role: text_match

student_paper

The Effect of Ant Colony Proximity on Membracid Survivorship

2005Role: text_match

article

In situ photosynthetic freezing tolerance for plants exposed to a global warming manipulation in the Rocky Mountains, Colorado, USA

2004New PhytologistRole: text_match

chapter

Adaptive speciation

2004Role: text_match

article

Impact of the Western Thatching Ant (Formica obscuripes) on

2004URBEERole: text_match

article

Response of plant pathogens and herbivores to a warming experiment

2004EcologyRole: text_match

student_paper

What is the nature of the ant-aphid relationship?

2004Role: text_match

student_paper

Defensive strategy to nectar robbing in Ipomopsis aggregata: floral nectar as a tolerance trait

2003Role: text_match

article

Enhanced growth of sagebrush (Artemisia tridentata) in response to manipulated ecosystem warming

2003Global Climate ChangeRole: text_match

article

Integrating experimental and gradient methods in ecological climate change research

2003EcologyRole: text_match

article

Subalpine meadow flowering phenology responses to climate change: integrating experimental and gradient methods

2003Ecological MonographsRole: text_match

article

The responses of montane shrubs to spatial and temporal climate variation in

2003URBEERole: text_match

article

Plant community composition mediates both large transient decline and predicted long-term recovery of soil carbon under climate warming

2002Global Biogeochemical CyclesRole: text_match

student_paper

The effects of plant succession and ant nest on soil organic matter and soil moisture

2002Role: text_match

article

Control of litter decomposition in a subalpine meadow-sagebrush steppe ecotone under climate change

2001Ecological ApplicationsRole: text_match

article

Influence of Changes in Sagebrush on Gunnison Sage Grouse in Southwestern Colorado

2001The Southwestern NaturalistRole: text_match

article

Plant responses to experimental warming in a montane meadow

2001EcologyRole: text_match

student_paper

The relationship between abiotic factors and species-level self-similarity of sagebrush, Artemisia tridentata

2001Role: text_match

article

Climate change is affecting altitudinal migrants and hibernating species

2000Proceedings of the National Academy of ScienceRole: text_match

student_paper

Environmental effects on woody growth of sagebrush Artemisia tridentata

2000Role: text_match

article

Photosynthetic responses to a climate-warming manipulation for contrasting meadow species in the Rocky Mountains, Colorado, USA

2000Functional EcologyRole: text_match

article

Estimating species-area relationships from plot to landscape scale using species spatial-turnover data

1999OikosRole: text_match

article

Ecological Feedbacks to Global Warming: Extending Results from Plot to Landscape Scale

1998Role: text_match

student_paper

Topographic effects on upper elevation distribution and abundance of Artemisia tridentata Nutt

1998Role: text_match

article

High-temperature tolerance of Artemisia tridentata and Potentilla gracilis under a climate change manipulation

1996OecologiaRole: text_match

article

Global warming and soil microclimate: results from a meadow-warming experiment

1995Ecological ApplicationsRole: text_match

article

Shifting dominance within a montane vegetation community: results from a climate-warming experiment

1995ScienceRole: text_match

article

Palynology of Pinedale Sediments, Devlins Park, Boulder County, Colorado

1980Arctic and Alpine ResearchRole: text_match

article

Absolute Pollen Diagram of Redrock Lake, Boulder County, Colorado

1972Quaternary ResearchRole: text_match

article

Hydrologic and Biotic Effects of Grazing vs. Non-Grazing near Grand Junction, Colorado

1970Journal of Range ManagementRole: text_match

student_paper

A study of plant succession on the Gothic earthflow

1969Role: text_match

Document

Homestake Mining Company Pitch Project Environmental Statement

Document

Moist Forests

technical report

Potential Uses of Abandoned Underground Mines

technical report

Proceedings of the Third Intermountain Meadow Symposium

environmental assessment

Signed Candidate Conservation Agreement with Assurances with its included Certifcate of Inclusion template for Gunnison Sage Grouse

wildlife survey

Small Mammals: A Beaver Pond Ecosystem and Adjacent Riparian Habitat in Idaho

technical report

Stream Channel Recerence Sites: An Illustrated Guide to Field Technique

environmental assessment

Vegetation Appendix Materials for Vegetation and Wildlife Studies for the Mount Emmons Project

environmental assessment

Vegetation and Wildlife Studies for the Mount Emmons Project

environmental assessment

Artemisia

Local Knowledge Graph (Top 81 entities)

Publications (134)

Depth of nutrient uptake by deep-rooted plants is regulated by water availability

Experimental warming decouples plant-fungal symbiont interactions and leads to a more conservative ecosystem

Fitness costs and benefits of a non-native floral resource for subalpine solitary bees

Associations Between Deer Browse and Aphid Colonization in a Long-Term Monitoring Study of Liguisticum porteri

Getting to the Root of It: Effects of Castilleja Root Hemiparasitism on Plant Community Structure and Function

Indirect effect of black bears on sunflowers in nitrogen-polluted and pristine steppe

Scaling Landscape Fire History: Wildfires Not Historically Frequent in the Main Population of Threatened Gunnison Sage-Grouse

Climate lags and genetics determine phenology in quaking aspen (Populus tremuloides)

Documents (20)

1980

A Classification of the Riparian Vegetation of the Gunnison River Basin, Colorado

An Illustrated Guide to the Proposed Threatened and Endangered Plant Species in Colorado

Appendix 2 List of Designated Colorado Natural Areas, List of Registered Colorado Natural Areas, List of Identified Colorado Natural Areas

Candidate Conservation Agreement With Assurances for Gunnison Sage-grouse (Centrocerucus minimus) between the Colorado Division of Wildlife and the U.S. Fish and Wildlife Service

Colorado Ranch Management School (Part 2)

Colorado Ranch Management School (Part 5)

Department Of Energy Compliance With Floodplain – Wetlands Environmental Review Requirements

Draft Environmental Impact Statement

Draft: Environmental Assessment of the Proposed Remedial Action at the Gunnison Uranium Mill Tailings Site

Co-occurring Species

A. tridentata

Artemisia tridentata

Erigeron

Potentilla

Ligusticum porteri

Delphinium

Festuca

Lupinus

Helianthella

Asteraceae

Demographic responses of hybridizing cinquefoils to changing climate in the Colorado Rocky Mountains

Effects of microclimate, dispersal, species interactions, and environmental stochasticity on demography

Effects of warming, dominant species removal, and accelerated snowmelt on aboveground plant traits in the Colorado Rocky Mountains

Herbivory damage but not plant disease under experimental warming is dependent on weather for three subalpine grass species

Historical fire regimes and contemporary fire effects within sagebrush habitats of Gunnison Sage‐grouse

Sage-Grouse

Phenotypic plasticity and selection on leaf traits in response to snowmelt timing and summer precipitation

Revealing the direct and indirect effects of climate change on soil nutrient dynamics and forage resources in mountain ecosystems

The Effect of Climate Change on Soil Organic Carbon over an Elevational Gradient

Changes in hunting season regulations (1870s–2019) reduce harvest exposure on greater and Gunnison sage-grouse

Chronic, low-level nitrogen deposition enhances abundances of ant-protected herbivores inhabiting an imperiled foundation species

Cytotype and genotype predict mortality and recruitment in Colorado quaking aspen (<i> Populus tremuloides </i>)

Effects of early snowmelt on plant phenophase timing and duration across an elevation gradient

Snow melt timing acts independently and in conjunction with temperature accumulation to drive subalpine plant phenology

Bee phenology is predicted by climatic variation and functional traits

Low predictability of energy balance traits and leaf temperature metrics in desert, montane and alpine plant communities

Remote Sensing-Informed Zonation for Understanding Snow, Plant and Soil Moisture Dynamics within a Mountain Ecosystem

Remote sensing of ploidy level in quaking aspen (<i>Populus tremuloides</i> Michx.)

The Snowmelt Niche Differentiates Three Microbial Life Strategies That Influence Soil Nitrogen Availability During and After Winter

Comparing predictive measures and model functions for estimating plant biomass: lessons from a sagebrush–rabbitbrush community

Depth- and time-resolved distributions of snowmelt-driven hillslope subsurface flow and transport and their contributions to surface waters.

Identifying the Impact of Biotic Interactions on Meadow Species Distributions in Sagebrush and Bunchgrass Dominated Systems

Investigating Microtopographic and Soil Controls on a Mountainous Meadow Plant Community Using High-Resolution Remote Sensing and Surface Geophysical Data

Parasitism modifies the direct effects of warming on a hemiparasite and its host

A model for leaf temperature decoupling from air temperature

Chemotypic variation in oshá (<i>Ligusticum porteri</i>) in Colorado, USA

Climate Warming Drives Local Extinction: Evidence from Observation and Experimentation

First-order controls of soil and leaf moisture

Rocky Mountain Biological Lab. Ecology of Place: Making Ecology and Evolutionary Biology spatially explicit

Short-term, low-level nitrogen deposition dampens a trophic cascade between bears and plants

The Effect of Climate Change on Plant Communities in the Rocky Mountains: How floral traits differ along an elevational gradient and in reciprocally transplanted communities

The impacts of early snowmelt and summer precipitation on the physiology and leaf morphology of <i>Ipomopsis aggregata</i>

Integrating viability and fecundity selection to illuminate the adaptive nature of genetic clines

Intraspecific variation in traits reduces ability of trait-based models to predict community structure

Effects of climate change on phenologies and distributions of bumble bees and the plants they visit

Productivity of Montane Meadows in a Warming World: Evidence from an Elevation Gradient and a Warming Experiment

The Changing Floral Color Landscape Across an Alpine Elevation Gradient

The Effects of Ants on Ecosystem Dynamics: Investigating the Ecological Influence of Ant Nests in the Rocky Mountains

Convergent ecosystem responses to 23-year ambient and manipulated warming link advancing snowmelt and shrub encroachment to transient and long-term climateâ€“soil carbon feedback

Elevational and temporal variation in Ipomopsis floral and vegetative traits.

Geographic variation in flowering phenology in Boechera stricta: testing for adaptive response to climate across the species range

Nest Success of Gunnison Sage-Grouse in Colorado, USA

Plasticity in functional traits in the context of climate change: A case study of the subalpine forb Boechera stricta (Brassicaceae)

Aboveground and belowground traits of dominant and sub-dominant species along an elevational gradient.

Changes in ant community composition caused by 20 years of experimental warming vs.13 years of natural climate shift

Coyotes, deer, and wildflowers: diverse evidence points to a trophic cascade

Human activity affects the perception of risk by mule deer