Carbon isotope variation in shrub willow (Salix spp.) ring-wood as an indicator of long-term water status, growth and survival Laura A. Schifman a, * ,1 , John C. Stella a , Timothy A. Volk a , Mark A. Teece b a Department of Forest and Natural Resources Management, State University of New York College of Environmental Science and Forestry, Syracuse, NY 13210, USA b Department of Chemistry, State University of New York College of Environmental Science and Forestry, Syracuse, NY 13210, USA article info Article history: Received 7 August 2011 Received in revised form 27 October 2011 Accepted 30 October 2011 Available online 16 November 2011 Keywords: Biomass energy Restoration Phytoremediation Shrub willow management Carbon stable isotope Water stress abstract Quantifying interannual change in water status of woody plants using stable carbon isotopes provides insight on long-term plant ecophysiology and potential success in vari- able environments, including under-utilized agricultural land for biomass production and highly disturbed sites for phytoremediation applications. We analyzed d 13 C values in annual ring-wood of four shrub willow varieties used for biomass production and phy- toremediation at three sites in central New York State (U.S.A). We tested a cost-effective sampling method for estimating whole-shrub water status by comparing d 13 C values of the plant’s largest stem against a composite sample of all stems. The largest stem showed 0.3& 13 C enrichment (range 0.7e1.1&) compared to the whole-plant, making it a more sensitive indicator of water status than the composite sample. Growing season precipita- tion exerted a strong negative influence on wood tissue chemistry, with an average 0.26& 13 C depletion per 100 mm increase in precipitation. An average annual 0.28& 13 C enrich- ment was also observed with increased plant age; this pattern was consistent among all four willow varieties and across sites. Finally, increased 13 C enrichment in wood tissue was positively associated with plant size at the individual plant level, and associated negatively and more variably survival at the plot scale. These results have important implications for the design and management of biomass production and phytoremediation systems. Increased sensitivity of older plants suggests that longer rotations may experience growth limitations and/or lower survival in low-precipitation years, resulting in reduced yields of biomass crops and loss of effectiveness in phytoremediation applications. ª 2011 Elsevier Ltd. All rights reserved. 1. Introduction Plants demonstrate an array of adaptations to conditions that diminish productivity and vitality [1,2]. One of these adapta- tions includes tolerance to long-term water limitation [1e3]. This is particularly advantageous for plants that grow in arid regions; however, plants that grow in mesic regions have to endure water-limiting conditions during dry periods as well [4,5]. These can have negative effects on physiological func- tions, net productivity and, during prolonged droughts, plant * Corresponding author. 330 Woodward Hall, University of Rhode Island, 9 E. Alumni Avenue, Kingston, Rhode Island 02881, USA. Tel.: þ1 201 925 2432; fax: þ1 401 874 2190. E-mail address: lschifman@my.uri.edu (L.A. Schifman). 1 Present affiliation: Department of Geosciences, University of Rhode Island, Kingston, RI 02881, USA. Available online at www.sciencedirect.com http://www.elsevier.com/locate/biombioe biomass and bioenergy 36 (2012) 316 e326 0961-9534/$ e see front matter ª 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.biombioe.2011.10.042