fire effects on chaparral-associated …...chaparral at 3,000- 3,500 ft elevation • from the heart...

FIRE EFFECTS ON CHAPARRAL-ASSOCIATED MAMMALS

PROGRESS ON A MULTI-YEAR STUDY FOLLOWING THE CEDAR FIRE

Wayne Spencer - Conservation Biology InstituteJay Diffendorfer - Illinois Natural History SurveyScott Tremor - San Diego Natural History MuseumJan Beyers - USDA Forest Service, Pacific Southwest Research StationGenie Fleming - San Diego Natural History MuseumJulio Angel Soto-Centeno - San Diego Natural History MuseumJenny Duggan - San Diego State UniversityDana Morin - San Diego State UniversityDana Hogan - San Diego State UniversityPaul Schuette - San Diego State University

Funded by USDA/USDI Joint Fire Science Program

Presenter�

Presentation Notes�

I’m just the presenter of this highly collaborative study. I won’t know all answers on all details. Scott coordinating field surveys through the SD Natural History Museum; Jay and Genie doing most of the analyses; Jan and Genie running botanical surveys; Angelo running the bat surveys; Paul running the carnivore surveys. This study an offshoot of SD County Mammal Atlas project.�

W. Spencer

S. Tremor S. Tremor

P. Levine

Short-term Fire Impacts on Mammals

Presenter�


Fire has immediate consequences for wildlife, but not as severe as often perceived. After the fires, many dead rabbits and woodrats observed. Large mammals seen in urban areas and killed by traffic. But most burrowing animals survived, and some others hung out in culverts, etc. Near burned areas Boulder Creek Road 61 Rabbits 28 Woodrats 9 Voles �

Study Goals: Longer-term fire

effectsFollowing the largest wildfire event in recent

California history:• Track changes in

– Community composition – Species’ distribution– Species’ abundance

• For chaparral-associated mammals:– Rodents– Bats– Carnivores

• As functions of– Fire severity– Distance from unburned edge– Time since fire

Inform fuels management efforts in a hotspot of biological diversity.

D. Hogan

G. & B. Corsi

San Diego Zoo

Presenter�


Note that others (Quinn, Keeley, others?) have monitored mammal populations following fire, but never on a fire this large (enabling us to look at spatial patterns of recovery), for this long (true???), or for this wide a range of species (true???). (Schwilk, D. W., & Keeley, J. E. (1998). Rodent populations after a large wildfire in California chaparral and coastal sage scrub. Southwestern Naturalist, 43(4), 480-483.) �

Study Area Primary Study Area• Community patterns (rodents, bats, and carnivores)• Burned and unburned chaparral at 3,000- 3,500 ft elevation• From the heart of the Cedar Fire to outside its southern perimeter

Secondary Study Area• Rodent demography• Burned and unburned coastal sage scrub.• Pre- and post-burn capture-recapture data

Cedar Fire

Otay Fire

Presenter�


This talk focuses on preliminary results concerning community and species occupancy patterns in the Cedar Fire study area; but I will also refer to some findings of the finer-scale population-level monitoring at RJER (Otay Fire) where they complement or help explain the Cedar Fire results. The RJER study is being led by Jay Diffendorfer and his students in parallel with this one, with the added benefit of 2 years of pre-fire data. Note that the maps that follow shiow the Cedar Fire study window, with the southern fire perimeter shown as a red line. �

Methods - Rodents• Repeated-measures

sampling design based on occupancy methods of MacKenzie et al. (2002, 2003)

• 40 study plots: – 30 burned

• Ranging from burn edge to ~8 km into burn interior

• Covering range of burn severities

– 10 unburned• 30 Sherman live traps per

plot• Sampled spring and fall for

5 consecutive nights

D. Hogan

Methods – Bats• 36 passive

ultrasonic monitoring stations– 12 unburned– 12 burn edge– 12 burn interior

• Sampled each summer for 3 nights each

• 3 roving survey transects– Unburned– Burn edge– Burn interior

A. Soto-Centano

M. Tuttle

Methods - Carnivores• Game-Vu camera

stations & gypsum track stations– 11 Unburned– 11 Burn edge– 10 Burn interior

• Sampled 3 times per year (winter, spring, fall) for 8 consecutive nights each

P. Schuette

Methods – Vegetation and Other Environmental Variables

• Annual vegetation sampling:– 100 point intercepts per plot– 20 1-m2 quadrats per plot

• Plant cover and height by species and growth form

• Percent ground cover by litter, duff, cryptobiotic crust, etc.

• Burn severity index using shrub skeleton diameters (Keeley 1998)– 40 shrub skeletons/plot

• Distance to “fire refugia”• Soil characteristics

W. Spencer

J. Duggan

W. Spencer

Presenter�


Absolute and relative cover by: Species Origin Growth form Mean maximum height by species and growth form �

Methods - Analyses• Today:

– Focus on rodent data, using two measures at each site:• Species presence (occupancy)• Species abundance (# unique captures)

– Use hierarchical linear modeling (HLM & HGLM) to explore trends.

• Regression-style, repeated measures techniques• Use burn severity and distance from unburned edge

as covariates

• Eventually: – More complete analyses on all taxa – Use occupancy modeling techniques that control for

differential detection rates– Increased use of multivariate techniques

Presenter�


Note focus is on rodent data for today, with some preliminary observations on bats and carnivores. HLM (linear regression style technique) was used for abundance analyses and HGLM (logistic regression style or generalized linear modeling) was used for presence analyses. Note start of field sampling delayed until 13 months post-fire. Note all results to be considered with a grain of salt. Note pooling of PECABO and Chaeto spp.?�

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Chaetodipus californicus & fallaxDipodomys simulansNeotoma lepidaP. californicus & boyliiPeromyscus eremicusPeromyscus maniculatus

• Community Composition Varies with Burn StatusResults - Rodents

W. Spencer

D. Hogan

K. DuBois

D. Hogan

D. Hogan

S. Tremor

D. Hogan

A. Mercieca

Dulzura Kangaroo Rats Consistently more common on burned areas.

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Dulzura Kangaroo Rat Abundance trends differ with burn severity.

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W. Spencer

Presenter�


13 months post fire, k-rat abundance was progressively lower on more severely burned plots, but the rate at which the more severely burned plots added individuals over time was slightly higher so that differences declined by 30 months post –fire. �

Pocket Mice (Chaetodipus fallax, C. californicus) Abundance trends vary with distance from unburned edge.

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D. Hogan

Presenter�


GF: Among burned plots the rate at which individuals were added or lost through time did not differ, but in general abundance declined as a function of distance from the burn perimeter so that plots further from the burn edge generally had fewer individuals �

Pocket Mice (Chaetodipus fallax, C. californicus) Occupancy declined following heavy rains on

burned sites.


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Record Rainfall D. Hogan

Presenter�


GF: I find it interesting that only pocket mice are showing this response. I think Jay said he found declines for other species in the NSF study, but we’re not seeing that here. What’s up with that? The pocket mice do seem to be more sensitive to cold when we’re trapping (poor little guys)…… Just musing……. �

Effects of Fire and Rain on San Diego Pocket Mouse, Rancho Jamul Ecological Reserve

Chaetodipus fallax

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Otay FireRecord winter rains

Brush Mice and California Mice Consistently more common on unburned sites, but evidence of recolonization on burned sites.


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D. Hogan

Brush Mice and California Mice Weak evidence that fire severity effects abundance trends.

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Presenter�


GF: The rate at which burned plots added individuals increased with burned severity. What’s up with that? Do you think there is some biological reason these mice might benefit from a more severely burned landscape? Will be interesting to see if this trend gets stronger with additional sessions or turns out to be “spurious”. Oh and by the way, after this latest trapping session, my totally un-mammological opinion is that we are really catching mostly PECA, and if we do catch PEBO they are rare. But I am a plant specialist……. �

Deer Mice Somewhat more widespread on burned sites.


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Deer Mice Weak evidence of abundance trends varying with fire severity.

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K. DuBois

Presenter�


GF: More severely burned plots appeared to add individuals at slightly higher rates through most of the study period. At least this is consistent with the effect shown for California mice. Would be nice to know if the additions were due to in situ reproduction or immigration, but we didn’t get to it. Maybe something to mention for future directions! �

Cactus Mice No difference in occupancy between burned and

unburned sites.


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Cactus Mice No difference in abundance or trends between burned

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Desert Woodrats Low occupancy everywhere; but evidence of

recolonization following fire.


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Bats – Calls Recorded by Burn Status

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Bat Distribution Relations to burn, unburn, and edge

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COTO EPFU EUPE MYCA MYCI MYYU NYFE PIHE TABR

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Photos: M.D. Tuttle

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Carnivore Detection Patterns

• Bobcats detected most often in unburned

• Coyotes detected least often in burn interior

• Gray fox detected most often in burn interior

Presenter�


Differences are very subtle and should be interpreted with caution. Spatial avoidance by gray fox (coyote dominant) But, also some overlap in activity across seasons and site types �

Tentative Conclusions• More time (and multivariate

analyses) may reveal additional patterns

• Influences on post-fire recovery of chaparral mammal fauna:– Not so important?

• Fire size• Fire severity

– Perhaps more important?• Fire-return intervals (burn

frequency) and type conversion• Fire patchiness

• Avoid extrapolating chaparral results to other communities:• E.g., montane forests

L. Ingles

Source: Keeley (2001)

fire effects on chaparral-associated …...chaparral at 3,000- 3,500 ft elevation • from the heart...

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