The vegetation of Dinosaur National Monument and surrounding lands (~298,000 ha) was reconstructed in a GIS using the General Land Office (GLO) survey records. This historical dataset was compared to modern vegetation datasets to determine how vegetation has changed over 90 years. Significant net declines in piñon-juniper woodland and montane shrubland occurred, along with large increases in sagebrush shrubland. Shorter natural and human-caused fire rotations appear to be driving woodland contraction. Some natural piñon-juniper expansion did occur near historical piñon-juniper-sagebrush ecotones, and particularly at elevations of 2000-2400 m and slopes of 10-30%. If trends continue, an artificial landscape with significantly more early seral sagebrush and grassland and less piñon-juniper woodland will emerge. Declines of piñon-juniper shown in Dinosaur National Monument and surrounding lands are similar to the recent loss of woodland in Mesa Verde National Park, Colorado, and suggest that historical woodlands on the Colorado Plateau may be declining due to an excess of fire since Euro-American settlement.

1. in the area of Dinosaur National Monument, Colorado/Utah

2.  Piñon-juniper covers 40 x 106
ha in Western U.S.
 Expansion over past 100-150
years[1,2]
• 33% increase from 1966-
1995[3]
• 150-625% increase since
1860[4]
 Potential drivers[5]
 Fire exclusion
 Over-grazing
 Climate change
Expansion in the Shoshone Mountains, Nevada [4]

3.  Dynamics & drivers spatially variable
 Reference conditions lacking in many areas of
Western U.S.[5]
 In contrast
 Minimal expansion on Uncompahgre Plateau in western
CO[6]
 Severe drought in Southwest 2002-2003 resulted in
mortality >90%[7]
 Expansion actually recovery from Euro-American land
uses[8]
 Still, piñon-juniper is the subject of many supposed
restoration treatments

4. “Increasingly complex
interactions between fire
and invasive species have
begun to present
unprecedented
complications for park
managers, leading to the
need for a comprehensive
assessment of current
landscape condition,
analysis of historical
patterns of change, and an
improved understanding of
the past and future role of
fire in Dinosaur’s unique
environment.”

5.  Spatial extent of piñon-
juniper in late 19th/early 20th
century Dinosaur National
Monument (DINO) unknown
 Early aerial & landscape
photographs not early or
comprehensive enough
 General Land Office (GLO)
survey records provide
necessary spatial and
temporal scales[9]

6.  GLO survey records
 Detailed and comprehensive
 Focus on line data, not point data (bearing trees)
 General description of dominant over- and understory species at
beginning/end of line
 Entry and exit points of forested and non-forested areas to nearest link (.2
m)
 Data entered into VBA entry form → MS Access database
Diagram from geology.isu.edu

7.  Two study areas
 Focus on DINO (52,936 ha)
 Larger area outside DINO (245,027 ha)
 Rugged terrain inside DINO not always surveyed
 Compare trends inside DINO to those of the adjacent area

8. Hypotheses
H1A) Piñon-juniper woodlands expanded in range over the past 100 years into the adjoining
sagebrush shrublands.
H1B) Piñon-juniper expansion occurred proximal to the piñon-juniper woodland-sagebrush
shrubland ecotone (i.e., within 200 m of the ecotone).
H2A) The recent fire rotation in piñon-juniper woodlands is longer, due to fire exclusion, than the
historical rotation.
H2B) The recent fire rotation in sagebrush is longer, due to fire exclusion, than the historical
rotation.
H3A) Piñon-juniper expansion was influenced by biophysical environment, evidenced by sites that
were either conducive or resistant to tree establishment.
H3B) Piñon-juniper contraction was strongly correlated with the occurrence of fire.

9.  H1A - Woodland expansion
 Historical and modern (NPS and ReGAP) datasets intersected
 H1B - Woodland expansion relative to ecotones
 Distance measured from piñon-juniper expansions to historical
piñon-juniper-sagebrush ecotones
 One-tailed t-test (greater than 200 m)
 H2A/H2B - Fire in piñon-juniper and sagebrush
 Modern fire rotations (FR) calculated from GIS dataset compiled
from multiple sources (1981-2000)
 Compared to commonly reported measures of historical fire
rotation

10.  H3A - Piñon-juniper expansion and the biophysical
environment
 Chi-square tests to compare distribution of settings
selected by expansion against distribution of settings
found in study area
 Elevation, slope, aspect, topographic position, soils
 H3B - Piñon-juniper contraction and fire
 % of piñon-juniper that converted to other ecosystems
from fire from 1981-2000
 Extrapolate to determine if fire could explain
contraction since 1910

11.  H1A - Woodland expansion
 GLO/ReGAP intersection showed contraction of piñon-juniper (& montane
shrubland), expansion of grassland/sagebrush – H1A rejected

12.  H1A - Woodland expansion
 GLO/NPS intersection showed net contraction of piñon-
juniper, net expansion of sagebrush – H1A rejected

13.  H1B - Woodland expansion relative to ecotones
 Expansion not confined to 200 m (M = 339.40, SD = 712.60) – H1B
rejected, though much expansion did occur close to ecotone

14.  Expansion occurred over much of study area at a fine grain
 Large patches north of Yampa River, northwestern and southeastern regions

15.  H2A/2B inside DINO - Fire in piñon-juniper and sagebrush
 Recent FR in piñon-juniper of 188 years < 400-600 years – H2A rejected
 Recent FR in Wyoming/Basin big sagebrush of 53 years < 2,500-5,000 years – H2B rejected
 Recent FR in mountain big sagebrush of 166 years < 458-729 years – H2B rejected
 Most fire in sagebrush from resource-management burning, natural FR also short
Total line Human-caused:
length or resource Human-caused: Human- Natural: Unknown
Vegetation Types area management unspecified caused: Total lightning cause Total fire
INSIDE DINOSAUR
Piñon-juniper 329.79 km 9.21 km 0.02 km 9.23 km 24.39 km 0.00 km 33.62 km
27.4% 0.1% 27.5% 72.6% 0.0% 100.0%
687 years 686 years 259 years 188 years
Wyoming/Basin big sagebrush 43.15 km 9.35 km 0.82 km 10.17 km 5.57 km 0.00 km 15.74 km
59.4% 5.2% 64.7% 35.4% 0.0% 100.0%
88 years 82 years 149 years 53 years
Mountain big sagebrush 2.67 km 0.19 km 0.00 km 0.19 km 0.12 km 0.00 km 0.31 km
61.3% 0.0% 61.3% 38.7% 0.0% 100.0%
270 years 270 years 427 years 166 years
Montane shrubland 2.29 km 0.17 km 0.00 km 0.17 km 0.14 km 0.00 km 0.31 km
54.8% 0.0% 54.8% 45.2% 0.0% 100.0%
269 years 269 years 327 years 148 years
Whole AOI 421.16 km 28.45 km 1.93 km 30.38 km 38.95 km 0.00 km 69.33 km
41.0% 2.8% 43.8% 56.2% 0.0% 100.0%
284 years 266 years 207 years 117 years
Introduced vegetation 878.93 ha 1.70 ha 90.80 ha 92.50 ha 196.80 ha 0.00 ha 289.30 ha
0.6% 31.4% 32.0% 68.0% 0.0% 100.0%
3404 years 190 years 89 years 61 years

16.  H2A/2B outside DINO - Fire in piñon-juniper and sagebrush
 Recent FR in piñon-juniper of 216 years < 400-600 years – H2A rejected
 Recent FR in Wyoming/Basin big sagebrush of 182 years < 2,500-5,000 years – H2B rejected
 Recent FR in mountain big sagebrush of years 976 years > 458-729 years – H2B supported
 Significantly less resource management burning than inside, but short natural FR
Total line Human-caused:
length or resource Human-caused: Human- Natural: Unknown
Vegetation Types area management unspecified caused: Total lightning cause Total fire
Outside Dinosaur
Piñon-juniper 1352.00 km 1.13 km 7.24 km 8.37 km 97.37 km 4.88 km 110.62 km
1.0% 6.5% 7.6% 88.0% 4.4% 100.0%
21225 years 2866 years 247 years 216 years
Wyoming/Basin big sagebrush 335.18 km 0.05 km 7.21 km 7.26 km 24.98 km 0.52 km 32.76 km
0.2% 22.0% 22.2% 76.3% 1.6% 100.0%
118922 years 819 years 238 years 182 years
Mountain big sagebrush 20.36 km 0.00 km 0.02 km 0.02 km 0.35 km 0.00 km 0.37 km
0.0% 0.0% 5.4% 94.6% 0.0% 100.0%
976 years
18059 years 1032 years
Montane shrubland 31.03 km 0.00 km 0.18 km 0.18 km 0.77 km 0.09 km 1.04 km
0.0% 17.3% 17.3% 74.0% 8.7% 100.0%
3448 years 806 years 597 years
Whole AOI 2155.92 km 1.19 km 30.82 km 32.01 km 154.84 km 6.52 km 193.37 km
0.6% 15.9% 16.6% 80.1% 3.4% 100.0%
32140 years 1195 years 247 years 198 years

17.  H3A - Piñon-juniper
expansion and the
biophysical environment
 Preference for elevations of
2000-2400 m, intermediate
slopes of 10-30%

18.  H3B - Piñon-juniper contraction and fire
 Contraction 1981-2000 was associated with fire, supporting H3B
 If same rate of contraction from natural fire occurred 1910-1981, and was combined with contraction
from all 1981-2000 fires (natural and resource management burning), ~86% contraction inside DINO
and ~98% contraction outside explained by fire

19.  H1A - Woodland expansion
 Net decreases in woodland, increases in shrubland
 Previous studies used small samples, & focused on changes in density, not
historical/modern ecotones[11,12]
 H1B - Woodland expansion relative to ecotones
 Most expansion did occur close to the ecotone
 Short-range and long-range dispersal agents
 H2A/2B - Fire in piñon-juniper and sagebrush
 Modern rotations in piñon-juniper and sagebrush (most) are short compared to
historical
 Inside DINO, resource-management burning causing much of the accelerated FR;
both in and out, natural rotations are shorter (likely cheatgrass, possibly climate
change)

20.  H3A - Piñon-juniper expansion and the biophysical
environment
 Expansion showed preference with only two variables,
elevation and slope, consistent with some studies
 Expansion or simply post-fire recovery?
 H3B - Piñon-juniper contraction and fire
 Contraction strongly associated with fire
 Previous studies have only examined areas of expansion

21.  Current public land management paradigms
 Fire exclusion has led to unnatural shifts in vegetation → fire
must be reintroduced [16]
 Long-term spatially extensive data from the GLO surveys
reveal otherwise
 Century-scale dynamics involve spatially heterogeneous
expansion and contraction of several ecosystems,
mediated by natural fire and human land uses

22.  Significant losses also occurred recently in
Mesa Verde National Park, Colorado[19]
 Losses in DINO and Mesa Verde give
support to paradigm of woodlands in
decline on the Colorado Plateau from
excessive fire since Euro-American
settlement

23.  If the goal is to preserve natural vegetation of DINO
 Piñon-juniper woodlands should become an ecosystem of
conservation
 Direct control of cheatgrass
 Cessation of prescribed burning inside DINO
 Aggressive suppression of human-set fires inside and outside
DINO
 Such measures may help increase the park’s resistance
and resilience to increased future fire, and would help
to restore the historical range of woodlands found
nearly a century ago

24.  National Park Service
 Dr. William Baker
 Dr. Steve Prager & Dr. Ken Driese

25.  [1] Archer, S. (1989) Have southern Texas savannas been converted to woodlands in recent history? The American Naturalist,
134, 545-561.
 [2] Van Auken, O.W. (2000) Shrub invasion of North American semiarid grasslands. Annual Review of Ecology and Systematics,
31, 197-215.
 [3] Weisberg, P.J., Lingua, E., & Pillai, R.B. (2007) Spatial patterns of pinyon-juniper woodland expansion in central Nevada.
Rangeland Ecology and Management, 60, 115-124.
 [4] Miller, R.F., Tausch, R.J., McArthur, E.D., Johnson, D.D., & Sanderson, S.C. (2008) Age structure and expansion of piñon-
juniper woodlands: a regional perspective in the Intermountain West. USDA Forest Service Research Paper RMRS-RP-69, Rocky
Mountain Research Station, Fort Collins, CO.
 [5] Romme, W.H., Allen, C.D., Bailey, J.D., Baker, W.L., Bestelmeyer, B.T., Brown, P.M., Eisenhart, K.S., Floyd, M.L., Huffman,
D.W., Jacobs, B.F., Miller, R.F., Muldavin, E.H., Swetnam, T.W., Tausch, R.J., & Weisberg, P.J. (2009) Historical and modern
disturbance regimes, stand structures, and landscape dynamics in piñon-juniper vegetation of the western United States.
Rangeland Ecology and Management, 62, 203-222.
 [6] Manier, D.J., Hobbs, N.T., Theobald, D.M., Reich, R.M., Kalkhan, M.A., & Campbell, M.R. (2005) Canopy dynamics and
human caused disturbance on a semi-arid landscape in the Rocky Mountains, USA. Landscape Ecology, 20, 1-17.
 [7] Breshears, D.D., Cobb, N.S., Rich, P.M., Price, K.P., Allen, C.D., Balice, R.G., Romme, W.H., Kastens, J.H., Floyd, M.L., Belnap,
J., Anderson, J.J., Myers, O.B., & Meyer, C.W. (2005) Regional vegetation die-off in response to global-change-type drought.
Proceedings of the National Academy of Sciences, 102, 15144-15148.

26.  [8] Sallach, B.K. (1986) Vegetation changes in New Mexico documented by repeat photography. Thesis, New Mexico State
University, Las Cruces.
 [9] Galatowitsch, S.M. (1990) Using the original land survey notes to reconstruct presettlement landscapes in the American
West. Great Basin Naturalist, 50, 181-191.
 [11] Soulé, P.T., & Knapp, P.A. (1999) Western juniper expansion on adjacent disturbed and near-relict sites. Journal of Range
Management, 52, 525-533.
 [12] Miller, R.F., & Rose, J.A. (1999) Fire history and western juniper encroachment in sagebrush steppe. Journal of Range
Management, 52, 550-559.
 [16] U.S. Dept. of Interior and U.S. Dept. of Agriculture. (2010) A national cohesive wildland fire management strategy.
http://www.forestsandrangelands.gov/