ArticlePublisher preview available

Climate and soil texture influence patterns of forb species richness and composition in big sagebrush plant communities across their spatial extent in the western U.S.

August 2017
Plant Ecology 218(8):957-970

DOI:10.1007/s11258-017-0743-9

Authors:

Kyle A. Palmquist

Marshall University

John Bradford

United States Geological Survey

William K. Lauenroth

Yale University

Big sagebrush (Artemisia tridentata Nutt.) plant communities are widespread in western North America and, similar to all shrub steppe ecosystems worldwide, are composed of a shrub overstory layer and a forb and graminoid understory layer. Forbs account for the majority of plant species diversity in big sagebrush plant communities and are important for ecosystem function. Few studies have explored geographic patterns of forb species richness and composition and their relationships with environmental variables in these communities. Our objectives were to examine the fine and broad-scale spatial patterns in forb species richness and composition and the influence of environmental variables. We sampled forb species richness and composition along transects at 15 field sites in Colorado, Idaho, Montana, Nevada, Oregon, Utah, and Wyoming, built species-area relationships to quantify differences in forb species richness at sites, and used Principal Components Analysis, non-metric multidimensional scaling, and redundancy analysis to identify relationships among environmental variables and forb species richness and composition. We found that species richness was most strongly correlated with soil texture, while species composition was most related to climate. The combination of climate and soil texture influences water availability, which our results indicate has important consequences for forb species richness and composition, and suggests that climate change-induced modification of soil water availability may have important implications for plant species diversity in the future. [Springer Nature SharedIt Initiative Full-Text Article Available : http://rdcu.be/tFJu].

Locations and names of 15 big sagebrush field sites in the western United States. Sites were selected within 5 of the 7 Greater Sage-Grouse Management Zones

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Average species-area relationships across 3 transects at each site. Forb species richness was sampled along 3 240 m² transects at each site. Sites are ordered geographically from northeast to southwest by Management Zone: a Management Zone I: Great Plains, b Management Zone II: Wyoming Basins c Management Zone III: Southern Great Basin and d Management Zones IV: Snake River Plain and V: Northern Great Basin. Sites from Management Zones IV and V were combined because there was only 1 site in Management Zone V

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Slope and intercept values from log-transformed species–area relationships. The log-transformed intercept is an estimate of small-scale species richness, while the slope in log–log space is the rate of species accumulation with area and a metric of within site beta-diversity. The minimum and maximum values for each site are represented by bars, and the average values are represented by a circle. Sites are organized geographically from northeast to southwest by Management Zone. Dotted lines indicate the breaks between Management Zones. Sites from Management Zones IV and V were combined because there was only 1 site in Management Zone V. Sites were variable in their small-scale richness patterns and beta-diversity patterns (i.e., low richness at small scales and high beta-diversity, high small-scale richness and low beta-diversity, intermediate small-scale richness and intermediate beta-diversity, and extremely low small-scale richness and extremely high beta-diversity)

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Number of sites occupied by each forb species. There were 136 unique forb species found on 45 240 m² transects at 15 field sites in 7 western states. Species were ranked from most to least frequent. The 7 most frequently found species were all native and are indicated by numbers (1 = most frequently found at all sites, 7 = 7th most frequent species at all sites)

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Non-metric multidimensional scaling of presence of forb species (a) and genera (b) with an overlay of environmental variables (Precip = MAP, Elev = elevation, Silt = percent silt) with p < 0.001 for 45 transects in 15 field sites. The three transects from each site are shown with a unique symbol. Sites shown in the same color are in the same Management Zone. Sites from Management Zones IV and V were combined because there was 1 site in Management Zone V

…

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Climate and soil texture inﬂuence patterns of forb species

richness and composition in big sagebrush plant

communities across their spatial extent in the western U.S.

Victoria E. Pennington .Kyle A. Palmquist .John B. Bradford .

William K. Lauenroth

Received: 11 November 2016 / Accepted: 13 June 2017 / Published online: 23 June 2017

ÓSpringer Science+Business Media B.V. (outside the USA) 2017

Abstract Big sagebrush (Artemisia tridentata Nutt.)

plant communities are widespread in western North

America and, similar to all shrub steppe ecosystems

worldwide, are composed of a shrub overstory layer

and a forb and graminoid understory layer. Forbs

account for the majority of plant species diversity in

big sagebrush plant communities and are important

for ecosystem function. Few studies have explored

geographic patterns of forb species richness and

composition and their relationships with environ-

mental variables in these communities. Our objec-

tives were to examine the ﬁne and broad-scale

spatial patterns in forb species richness and compo-

sition and the inﬂuence of environmental variables.

We sampled forb species richness and composition

along transects at 15 ﬁeld sites in Colorado, Idaho,

Montana, Nevada, Oregon, Utah, and Wyoming,

built species-area relationships to quantify differ-

ences in forb species richness at sites, and used

Principal Components Analysis, non-metric multi-

dimensional scaling, and redundancy analysis to

identify relationships among environmental vari-

ables and forb species richness and composition. We

found that species richness was most strongly

correlated with soil texture, while species compo-

sition was most related to climate. The combination

of climate and soil texture inﬂuences water avail-

ability, which our results indicate has important

consequences for forb species richness and compo-

sition, and suggests that climate change-induced

modiﬁcation of soil water availability may have

important implications for plant species diversity in

the future.

Keywords Biogeography Biodiversity Climate 

Greater Sage-Grouse Species-area relationship Soil

properties Sagebrush Artemisia tridentata

Communicated by Lauchlan Fraser.

Electronic supplementary material The online version of

this article (doi:10.1007/s11258-017-0743-9) contains supple-

mentary material, which is available to authorized users.

V. E. Pennington K. A. Palmquist W. K. Lauenroth

Department of Botany, University of Wyoming, Laramie,

WY 82071, USA

e-mail: kpalmqu1@uwyo.edu

J. B. Bradford

U.S. Geological Survey, Southwest Biological Science

Center, Flagstaff, AZ 86011, USA

e-mail: jbradford@usgs.gov

W. K. Lauenroth

School of Forestry and Environmental Studies, Yale

University, New Haven, CT 06511, USA

e-mail: William.Lauenroth@Yale.edu

V. E. Pennington (&)

Avian Science Center, College of Forestry and

Conservation, University of Montana, Missoula,

MT 59812, USA

e-mail: victoria.pennington4@gmail.com

123

Plant Ecol (2017) 218:957–970

DOI 10.1007/s11258-017-0743-9

Content courtesy of Springer Nature, terms of use apply. Rights reserved.

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