Soil moisture's underestimated role in climate change impact modelling in low‐energy systems

Shifts in precipitation regimes are an inherent component of climate change, but in low-energy systems are often assumed to be less important than changes in temperature. Because soil moisture is the hydrological variable most proximally linked to plant performance during the growing season in arctic-alpine habitats, it may offer the most useful perspective on the influence of changes in precipitation on vegetation. Here we quantify the influence of soil moisture for multiple vegetation properties at fine spatial scales, to determine the potential importance of soil moisture under changing climatic conditions. A fine-scale data set, comprising vascular species cover and field-quantified ecologically relevant environmental parameters, was analysed to determine the influence of soil moisture relative to other key abiotic predictors. Soil moisture was strongly related to community composition, species richness and the occurrence patterns of individual species, having a similar or greater influence than soil temperature, pH and solar radiation. Soil moisture varied considerably over short distances, and this fine-scale heterogeneity may contribute to offsetting the ecological impacts of changes in precipitation for species not limited to extreme soil moisture conditions. In conclusion, soil moisture is a key driver of vegetation properties, both at the species and community level, even in this low-energy system. Soil moisture conditions represent an important mechanism through which changing climatic conditions impact vegetation, and advancing our predictive capability will therefore require a better understanding of how soil moisture mediates the effects of climate change on biota.

[1]  R. Aerts,et al.  Tundra in the Rain: Differential Vegetation Responses to Three Years of Experimentally Doubled Summer Precipitation in Siberian Shrub and Swedish Bog Tundra , 2012, AMBIO.

[2]  Karsten Schulz,et al.  High resolution modelling of snow transport in complex terrain using downscaled MM5 wind fields , 2010 .

[3]  C. Nilsson,et al.  Arctic alpine vegetation change over 20 years , 2009 .

[4]  G. Henry,et al.  Patterns of Plant Distribution within Two Polar Desert Landscapes , 1994 .

[5]  Microtopographic heterogeneity constrains alpine plant diversity, Glacier National Park, MT , 2012, Plant Ecology.

[6]  H. Birks,et al.  Recent vegetation changes at the high‐latitude tree line ecotone are controlled by geomorphological disturbance, productivity and diversity , 2010 .

[7]  Josep Peñuelas,et al.  A global change‐induced biome shift in the Montseny mountains (NE Spain) , 2003 .

[8]  C. Körner,et al.  Topographically controlled thermal‐habitat differentiation buffers alpine plant diversity against climate warming , 2011 .

[9]  John Bell,et al.  A review of methods for the assessment of prediction errors in conservation presence/absence models , 1997, Environmental Conservation.

[10]  R. Hijmans,et al.  Cross-validation of species distribution models: removing spatial sorting bias and calibration with a null model. , 2012, Ecology.

[11]  T. Dawson,et al.  Spatial scale affects bioclimate model projections of climate change impacts on mountain plants , 2008 .

[12]  Donald A. Walker,et al.  Plant communities of a tussock tundra landscape in the Brooks Range Foothills, Alaska , 1994 .

[13]  J. Bale,et al.  Hydrology, water availability and tundra ecosystem function in a changing climate: the need for a closer integration of ideas? , 1999 .

[14]  Marco Borga,et al.  Hillslope scale soil moisture variability in a steep alpine terrain , 2009 .

[15]  M. Austin.  Spatial prediction of species distribution: an interface between ecological theory and statistical modelling , 2002 .

[16]  Martin Kopecký,et al.  Using topographic wetness index in vegetation ecology: does the algorithm matter? , 2010 .

[17]  A GIS Assessment of Alpine Biodiversity at a Range of Scales , 2003 .

[18]  Miska Luoto,et al.  Modelling the occurrence of threatened plant species in taiga landscapes: methodological and ecological perspectives , 2008 .

[19]  John P. Smol,et al.  Crossing the final ecological threshold in high Arctic ponds , 2007, Proceedings of the National Academy of Sciences.

[20]  T. Seastedt,et al.  Short- and Long-Term Patterns of Soil Moisture in Alpine Tundra , 1994 .

[21]  W. D. Billings,et al.  An Alpine Snowbank Environment and Its Effects on Vegetation, Plant Development, and Productivity , 1959 .

[22]  P. Choler,et al.  Small-scale plant species distribution in snowbeds and its sensitivity to climate change , 2008, Plant Ecology.

[23]  John-Arvid Grytnes,et al.  Local temperatures inferred from plant communities suggest strong spatial buffering of climate warming across Northern Europe , 2013, Global change biology.

[24]  P. Choler.  Consistent Shifts in Alpine Plant Traits along a Mesotopographical Gradient , 2005 .

[25]  M. Zappa,et al.  Climate change and plant distribution: local models predict high‐elevation persistence , 2009 .

[26]  T. Seastedt,et al.  Topographic controls on snow distribution, soil moisture, and species diversity of herbaceous alpine vegetation, Niwot Ridge, Colorado , 2008 .

[27]  V. Razzhivin,et al.  Broad-scale vegetation-environment relationships in Eurasian high-latitude areas , 2006 .

[28]  C. Schöb,et al.  The relationship between soil water storage capacity and plant species diversity in high alpine vegetation , 2013 .

[29]  M. Hájek,et al.  Do we need soil moisture measurements in the vegetation–environment studies in wetlands? , 2013 .

[30]  G. Liston,et al.  Introduction of Snow and Geomorphic Disturbance Variables into Predictive Models of Alpine Plant Distribution in the Western Swiss Alps , 2009 .

[31]  G. Hegerl,et al.  Detection of human influence on twentieth-century precipitation trends , 2007, Nature.

[32]  E. Haukioja,et al.  Growth response of subarctic dwarf shrubs, Empetrum nigrum and Vaccinium vitis-idaea, to manipulated environmental conditions and species removal , 1997 .

[33]  W. D. Billings.  ADAPTATIONS AND ORIGINS OF ALPINE PLANTS , 1974 .

[34]  Miska Luoto,et al.  Horizontal, but not vertical, biotic interactions affect fine-scale plant distribution patterns in a low-energy system. , 2013, Ecology.

[35]  L. Gough,et al.  Vascular plant species richness in Alaskan arctic tundra: the importance of soil pH , 2000 .

[36]  Harold A. Mooney,et al.  THE ECOLOGY OF ARCTIC AND ALPINE PLANTS , 1968 .

[37]  T. Callaghan,et al.  PLANT COMMUNITY RESPONSES TO SIMULATED ENVIRONMENTAL CHANGE AT A HIGH ARCTIC POLAR SEMI-DESERT , 1998 .

[38]  Delphis F. Levia,et al.  Soil moisture: A central and unifying theme in physical geography , 2011 .

[39]  C. Piedallu,et al.  Soil water balance performs better than climatic water variables in tree species distribution modelling , 2013 .

[40]  Diane Ebert-May,et al.  EFFECTS OF INTERANNUAL CLIMATE VARIATION ON ABOVEGROUND PHYTOMASS IN ALPINE VEGETATION , 1994 .

[41]  C. Dormann,et al.  Climate change in the Arctic: using plant functional types in a meta‐analysis of field experiments , 2002 .

[42]  David G. Chandler,et al.  Controls on the temporal and spatial variability of soil moisture in a mountainous landscape: the signature of snow and complex terrain , 2008 .

[43]  W. Lauenroth,et al.  Effects of ecohydrological variables on current and future ranges, local suitability patterns, and model accuracy in big sagebrush , 2012 .

[44]  S. Isard.  Factors Influencing Soil Moisture and Plant Community Distribution on Niwot Ridge, Front Range, Colorado, U.S.A. , 1986 .

[45]  S. Wood.  Fast stable restricted maximum likelihood and marginal likelihood estimation of semiparametric generalized linear models , 2011 .

[46]  H. H. Bruun,et al.  Effects of altitude and topography on species richness of vascular plants, bryophytes and lichens in alpine communities , 2006 .

[47]  S. Dobrowski.  A climatic basis for microrefugia: the influence of terrain on climate , 2011 .

[48]  Dylan Keon,et al.  Equations for potential annual direct incident radiation and heat load , 2002 .

[49]  M. Rietkerk,et al.  Ecohydrological advances and applications in plant-water relations research: a review , 2011 .

[50]  M. Araújo,et al.  Rethinking species' ability to cope with rapid climate change , 2011 .

[51]  M. Austin,et al.  Improving species distribution models for climate change studies: variable selection and scale , 2011 .

[52]  Jan Dick,et al.  Recent Plant Diversity Changes on Europe’s Mountain Summits , 2012, Science.

[53]  Harry John Betteley Birks,et al.  A comparative ecological study of Norwegian mountain plants in relation to possible future climatic change , 1997 .

[54]  G. Phoenix,et al.  Transition zones between vegetation patches in a heterogeneous Arctic landscape: how plant growth and photosynthesis change with abundance at small scales , 2010, Oecologia.

[55]  Jennifer A. Miller,et al.  Mapping Species Distributions: Spatial Inference and Prediction , 2010 .

[56]  W. D. Billings.  Arctic and Alpine Vegetations: Similarities, Differences, and Susceptibility to Disturbance , 1973 .

[57]  Edward B. Rastetter,et al.  Arctic and boreal ecosystems of western North America as components of the climate system , 2000, Global change biology.

[58]  Omri Allouche,et al.  Assessing the accuracy of species distribution models: prevalence, kappa and the true skill statistic (TSS) , 2006 .

[59]  John A. Lee,et al.  Effects of global change on a sub‐Arctic heath: effects of enhanced UV‐B radiation and increased summer precipitation , 2001 .

[60]  J Elith,et al.  A working guide to boosted regression trees. , 2008, The Journal of animal ecology.

[61]  S. Oberbauer,et al.  Drought tolerance and water use by plants along an alpine topographic gradient , 1981, Oecologia.

[62]  D. Walker,et al.  Hierarchical subdivision of Arctic tundra based on vegetation response to climate, parent material and topography , 2000, Global change biology.

[63]  Julian D. Olden,et al.  Assessing transferability of ecological models: an underappreciated aspect of statistical validation , 2012 .

[64]  James J. Roberts,et al.  Fragmentation and thermal risks from climate change interact to affect persistence of native trout in the Colorado River basin , 2013, Global change biology.

[65]  Ottar Michelsen,et al.  Continent-wide response of mountain vegetation to climate change , 2012 .

[66]  M. Caldwell,et al.  Gas exchange of four arctic and alpine tundra plant species in relation to atmospheric and soil moisture stress , 1975, Oecologia.

[67]  K. Beven,et al.  A physically based, variable contributing area model of basin hydrology , 1979 .

[68]  Eric M. Yuen,et al.  Fine-Scale Patterns of Soil and Plant Surface Temperatures in an Alpine Fellfield Habitat, White Mountains, California , 2012 .

[69]  J. Abatzoglou,et al.  Changes in Climatic Water Balance Drive Downhill Shifts in Plant Species’ Optimum Elevations , 2011, Science.

[70]  J. Zak,et al.  Assessing the Response of Terrestrial Ecosystems to Potential Changes in Precipitation , 2003 .

[71]  Antoine Guisan,et al.  Species distribution models reveal apparent competitive and facilitative effects of a dominant species on the distribution of tundra plants , 2010 .