LONG-TERM INTERACTIONS OF CLIMATE, PRODUCTIVITY, SPECIES RICHNESS, AND GROWTH FORM IN RELICTUAL SAGEBRUSH STEPPE PLANT COMMUNITIES

Abstract Vegetation trends due to climatic changes are difficult to separate from disturbances caused by varying land uses. To separate climatic influences from livestock grazing and fire disturbances within sagebrush steppe, we compared vegetation structure and productivity during 2 periods (10-year sequences of data from the late 1950s to the late 1960s and 3 years in the early 1990s) at 12 stands within 3 relict areas in or near the Great Rift of southern Idaho. Year-to-year fluctuations in annual net aboveground phytomass accumulation (ANAPA) were considerable in response to varying climate during both periods. More importantly, an apparently significant increase in ANAPA was observed during the latter study period. However, this apparent increase may have been due to the unusually wet conditions of 1993. Throughout both study periods, ANAPA was even more positively correlated with species richness than with precipitation, although both influences were statistically significant. Aggregation of these data by plant growth forms showed that shrubs, particularly sagebrushes, have progressively increased their proportion relative to herbaceous understory. This directional (successional) change in the proportional contributions of growth forms to ANAPA was probably due more to long-term absence of fire at these isolated locations than to any detectable climate change or lack of grazing. This finding reduces our confidence in the use of such areas as reference sites for monitoring or as living examples for restoration efforts, but it does increase our understanding of vegetation dynamics within sagebrush steppe. Acronyms.–ANAPA–annual net aboveground phytomass accumulations, ANOVA–analysis of variance, ANPP–aboveground net primary production, COV–coefficient of variation, CY–crop year, CYP–crop-year precipitation, ES–ecological site, MANOVA–multivariate analysis of variance, MAT–mean annual temperature, NRCS–Natural Resources Conservation Service, PDSI–Palmer Drought Severity Index, RUE–rainfall use efficiency.

[1]  L. Shultz,et al.  Development and longevity of ephemeral and perennial leaves on Artemisia tridentata Nutt , 1987 .

[2]  D. Wilhite,et al.  CHAPfER2UNDERSTANDING THE DROUGHT PHENOMENON:THE ROLE OF DEFINITIONS , 1985 .

[3]  Defoliation increased above-ground productivity in a semi-arid grassland , 2004 .

[4]  Kathryn A. Schoenecker,et al.  Do ungulates accelerate or decelerate nitrogen cycling , 2003 .

[5]  G. Stewart,et al.  Effects of the 1934 Drought on Native Vegetation of the Upper Snake River Plans, Idaho , 1937 .

[6]  M. Allen,et al.  Influence of parasitic and mutualistic fungi on Artemisia tridentata during high precipitation years , 1987 .

[7]  S. McNaughton,et al.  Evidence for the promotion of aboveground grassland production by native large herbivores in Yellowstone National Park , 1993, Oecologia.

[8]  Kevin C. Ryan,et al.  Vegetation and wildland fire: Implications of global climate change , 1991 .

[9]  J. Blaisdell.  Seasonal Development and Yield of Native Plants on the Upper Snake River Plains and their Relation to Certain Climatic Factors , 1958 .

[10]  D. Schimel,et al.  Mechanisms of shrubland expansion: land use, climate or CO2? , 1995 .

[11]  W. Alley.  The Palmer Drought Severity Index: Limitations and Assumptions , 1984 .

[12]  I. Noble.  Long-term Biomass Dynamics in an Arid Chenopod Shrub Community at Koonamore, South Australia , 1977 .

[13]  Potential effects of climate change on the temperate zones of North and South America , 2004 .

[14]  V. Squires,et al.  Available soil moisture as a basis for land capability assessment in semi arid regions , 2004, Vegetatio.

[15]  N. Saliendra,et al.  Winter CO2 fluxes above sagebrush-steppe ecosystems in Idaho and Oregon , 2004 .

[16]  P. G. Rowlands,et al.  Fishtail Mesa: a vegetation resurvey of relict area in Grand Canyon National Park, Arizona , 2001 .

[17]  Richard Miller,et al.  Spatial and temporal changes of sage grouse habitat in the sagebrush biome , 2000 .

[18]  N. West,et al.  Implications of livestock grazing in the intermountain sagebrush region: plant composition. , 1994 .

[19]  N. Saliendra,et al.  Growing season CO2 fluxes in a sagebrush-steppe ecosystem in Idaho: bowen ratio/energy balance measurements and modeling , 2003 .

[20]  L. Pearson.  Primary Productivity in a Northern Desert Area , 1965 .

[21]  J. C. Winslow,et al.  Numerical Terradynamic Simulation Group 3-2001 Mapping Weekly Rangeland Vegetation Productivity Using MODIS Algorithms , 2018 .

[22]  Jay T. Lennon,et al.  Knowing when to draw the line: designing more informative ecological experiments , 2005 .

[23]  N. West.  Western intermountain sagebrush steppe , 1983 .

[24]  W. Winner,et al.  RESPONSE OF SAGEBRUSH STEPPE SPECIES TO ELEVATED CO 2 AND SOIL TEMPERATURE , 2005 .

[25]  Donald McKenzie,et al.  Climatic Change, Wildfire, and Conservation , 2004 .

[26]  Timothy J. Hoar,et al.  The 1990–1995 El Niño‐Southern Oscillation Event: Longest on Record , 1996 .

[27]  Jay E. Anderson,et al.  LANDSCAPE‐SCALE CHANGES IN PLANT SPECIES ABUNDANCE AND BIODIVERSITY OF A SAGEBRUSH STEPPE OVER 45 YEARS , 2001 .

[28]  H. L. Houérou,et al.  Relationship between the variability of primary production and the variability of annual precipitation in world arid lands , 1988 .

[29]  L. Irwin,et al.  Climate-vegetation Relationships between the Great Plains and Great Basin , 1992 .

[30]  Clifton W. Johnson,et al.  Foliage Mortality of Mountain Big Sagebrush [Artemisia tridentata subsp. vaseyana] in Southwestern Idaho during the Winter of 1976-77 , 1982 .

[31]  G. Stewart,et al.  Sagebrush-grass range sampling studies: size and structure of sampling unit. , 1940 .

[32]  M. Loik,et al.  A multi-scale perspective of water pulses in dryland ecosystems: climatology and ecohydrology of the western USA , 2004, Oecologia.

[33]  R. Renkin,et al.  Effects of browsing by native ungulates on the shrubs in big sagebrush communities in Yellowstone National Park , 1995 .

[34]  Steward T. A. Pickett,et al.  Space-for-Time Substitution as an Alternative to Long-Term Studies , 1989 .

[35]  N. West,et al.  Viewpoint: delineating ecological sites. , 1999 .

[36]  S. Ferguson.  A Climate-Change Scenario for the Columbia River Basin , 1997 .

[37]  M. E. Thiede,et al.  Effects of coppice dune topography and vegetation on soil water dynamics in a cold-desert ecosystem , 1994 .

[38]  R. D. Ramsey,et al.  Spatiotemporal mapping of the dry season vegetation response of sagebrush steppe , 2004 .

[39]  F. Clements.  The Relict Method in Dynamic Ecology , 1934 .

[40]  Douglas A. Johnson,et al.  Soil morphology and organic matter dynamics under cheatgrass and sagebrush-steppe plant communities , 2004 .

[41]  P. Hosten.  Assessing the Relative Utility of Models of Vegetation Dynamics for the Management of Sagebrush Steppe Rangelands , 1995 .

[42]  S. Milton,et al.  Vegetation change in semiarid communities , 1996, Vegetatio.

[43]  C. Daly,et al.  A Statistical-Topographic Model for Mapping Climatological Precipitation over Mountainous Terrain , 1994 .

[44]  M. Pace,et al.  In a Nutshell: Ecological Science and Sustainability for the 21st Century Reviews Reviews Reviews , 2022 .

[45]  F. Giorgi,et al.  Regional Climate Change Scenarios over the United States Produced with a Nested Regional Climate Model , 1994 .

[46]  H. P. Bailey.  Toward a Unified Concept of the Temperate Climate , 1964 .

[47]  R. Daubenmire.  Climate as a Determinant of Vegetation Distribution in Eastern Washington and Northern Idaho , 1956 .

[48]  Gerald A. Meehl,et al.  Preparing for a changing climate : the potential consequences of climate variability and change , 2001 .

[49]  H. B. Passey,et al.  Relationships Between Soil, Plant Community, and Climate on Rangelands of the Intermountain West , 1982 .

[50]  L. Pearson.  Primary Production in Grazed and Ungrazed Desert Communities of Eastern Idaho , 1965 .

[51]  O. Loucks,et al.  From Balance of Nature to Hierarchical Patch Dynamics: A Paradigm Shift in Ecology , 1995, The Quarterly Review of Biology.

[52]  B. Welch.  Big sagebrush: A sea fragmented into lakes, ponds, and puddles , 2005 .

[53]  Understanding and managing rangeland plant communities. , 2002 .

[54]  M. Scheffer,et al.  El Niño effects on the dynamics of terrestrial ecosystems. , 2001, Trends in ecology & evolution.

[55]  D. Hyder,et al.  Estimating Herbage Production on Semiarid Ranges in The Intermountain Region. , 1962 .

[56]  T. Rabotnov.  Differences Between Fluctuations and Successions , 1974 .

[57]  Ze'ev Gedalof,et al.  A multi‐century perspective of variability in the Pacific Decadal Oscillation: new insights from tree rings and coral , 2002 .

[58]  P. Tueller,et al.  Vegetation stagnation in three-phase big game exclosures. , 1979 .