Water source niche overlap increases with site moisture availability in woody perennials
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Classical niche partitioning theory posits increased competition for and partitioning of the most limiting resource among coexisting species. Coexisting plant species may vary in rooting depth, reflecting niche partitioning in water source use. Our goal was to assess the soil water partitioning of woody plant communities across northern Arizona along an elevational moisture gradient using stem and soil water isotopes from two sampling periods to estimate the use of different water sources. We hypothesized that niche overlap of water sources would be higher and monsoon precipitation uptake would be lower at sites with higher moisture availability. Pairwise niche overlap of coexisting species was calculated using mixing model estimates of proportional water use for three sources. Across the moisture gradient, niche overlap increased with site moisture index (precipitation/potential evapotranspiration) across seasons, and site moisture index explained 37% of the variation in niche overlap of intermediate and deeper sources of water. Desert trees utilized more winter source water than desert shrubs, suggesting the partitioning of water sources between functional groups. However, seasonal differences in surface water use were primarily found at intermediate levels of site moisture availability. Our findings support classical niche partitioning theory in that plants exhibit higher overlap of water sources when water is not a limiting resource.
KeywordsCoexistence Niche overlap Water source Stable isotopes Plant communities Moisture gradient
The authors thank Hannah Russell for her assistance in the field and lab, Jaimie Brown and Kimberly Samuels-Crow for their expertise in stable isotopes, Derek Sonderegger for his statistical advice, and the Ogle Lab for comments on this manuscript.
JG was supported by a Science Foundation Arizona Graduate Research Fellowship under Award GRF 0449-10.
JG, TK, BH, and GK conceived and designed the study; JG conducted fieldwork and lab analyses; JG and BH analyzed data; JG wrote the manuscript; and BH, TK, and GK provided editorial advice.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
- Alexander RR, Shepperd WD (1984) Silvical characteristics of Engelmann spruce. General Technical Report. Rocky Mountain Forest and Range Experiment Station, USDA Forest ServiceGoogle Scholar
- Berndt HW, Gibbons RD (1958) Root distribution of some native trees and understory plants growing on three sites within ponderosa pine watersheds in Colorado. Rocky Mountain Forest and Range Experiment StationGoogle Scholar
- Brown DE (1994) Biotic communities: southwestern United States and northwestern Mexico. University of Utah Press, Salt Lake CityGoogle Scholar
- Center U.S.N.G.D. (1998) ETOPO-5 five minute gridded world elevation. NGDC, BoulderGoogle Scholar
- Clary WP, Tiedemann AR (1986) Distribution of biomass within small tree and shrub form Quercus gambelii stands. For Sci 32:234–242Google Scholar
- Cottam WP (1954) Prevernal leafing of aspen in Utah Mountains. J Arnold Arbor 35:239–250Google Scholar
- Cribari-Neto F, Zeileis A (2010) Beta regression in R. J Stat Softw 32:1–24Google Scholar
- Dawson T, Ehleringer J, Hall A, Farquhar G (1993) Water sources of plants as determined from xylem-water isotopic composition: perspectives on plant competition, distribution, and water relations. In: Stable isotopes and plant carbon–water relations. Academic, San Diego, p 465–496Google Scholar
- Hermann RK, Petersen RG (1969) Root development and height increment of ponderosa pines in pumice soils of central Oregon. For Sci 15:226–237Google Scholar
- IAEA/WMO (2011) Global network of isotopes in precipitation. The GNIP databaseGoogle Scholar
- Lowe CH (1964) Arizona’s natural environment: landscapes and habitats. University of Arizona Press, TucsonGoogle Scholar
- Miller G, Ambos N, Boness P, Reyher D, Robertson G, Scalzone K, Steinke R, Subirge T (1995) Terrestrial ecosystems survey of the Coconino National Forest. USDA Forest Service, Southwestern RegionGoogle Scholar
- Parnell AC, Phillips DL, Bearhop S, Semmens BX, Ward EJ, Moore JW, Jackson AL, Grey J, Kelly DJ, Inger R (2013) Bayesian stable isotope mixing models. Environmetrics 24:387–399Google Scholar
- PRISM Climate Group O.S.U. (2013) Gridded climate data for the contiguous USAGoogle Scholar
- R Core Team (2016) R: a language and environment for statistical computing. R Foundation for Statistical Computing, ViennaGoogle Scholar
- Sheldrick B, Wang C (1993) Particle size distribution. In: Soil sampling and methods of analysis. Lewis Publishers, Boca Raton, p 499–511Google Scholar
- Soil Survey Staff N.R.C.S., United States Department of Agriculture. Soil series classification databaseGoogle Scholar
- USGS (2017) National Water Information System data available on the World Wide Web (USGS Water Data for the Nation)Google Scholar
- Wershaw R, Friedman I, Heller S, Frank P (1966) Hydrogen isotopic fractionation of water passing through trees. In: Hobson GD, Speers GC, Inderson DE (eds) Advances in organic geochemistry. International series of monographs on earth sciences, vol 32. Pergamon Press, New York, pp 55–67Google Scholar
- Williams DG, Ehleringer JR (2000) Intra- and interspecific variation for summer precipitation use in pinyon-juniper Woodlands. Ecol Monogr 70:517–537Google Scholar