Variation in protein complexation capacity among and within six plant species across a boreal forest chronosequence Michael J. Gundale • Jennie Sverker • Benedicte R. Albrectsen • Marie-Charlotte Nilsson • David A. Wardle Received: 28 October 2009 / Accepted: 20 April 2010 / Published online: 4 May 2010 Ó Springer Science+Business Media B.V. 2010 Abstract We investigated among and within species variation in several litter chemical properties, including protein complexation capacity (PCC), for six plant species across a boreal forest chronose- quence in northern Sweden across which stand fertility declines sharply with stand age. We hypoth- esized (1) that evergreen species which dominate in late-successional stands would exhibit higher PCCs than deciduous species that dominate in young stands, (2) that individual species would increase their PCCs in response to nutrient limitation as succession proceeds, and (3) that differences in PCC among litter types would determine their interactive effects with proteins on soil N and C mineralization. The data demonstrated a high PCC, but a low PCC per unit of soluble phenol, for two deciduous species that dominate in early-successional high fertility stands, providing mixed support for our first hypoth- esis. No species demonstrated a significant correla- tion between their PCC and stand age, which did not support our second hypothesis. Finally, a soil incubation assay revealed that litter extracts for three of the six species had negative interactive effects with added proteins on N mineralization rates, and that all six species demonstrated positive interactive effects with protein on C mineralization. This pattern did not provide strong support for our third hypothesis, and suggests that N immobilization was likely a more important factor regulating N mineralization than stabilization of proteins into tannin complexes. These data suggest that multiple interactive mechanisms between litter extracts and proteins likely occur simultaneously to influence the availability of N in soils. Keywords Protein complexation  N mineralization  Litter  Succession  Polyphenols  Tannins  Chronosequence  Decomposition Introduction Nitrogen (N) is considered to be the most limiting nutrient for productivity in boreal forests (Tamm 1991), and the availability of N is, therefore, a major factor that affects species interactions and succes- sional dynamics (Aerts and Chapin 2000). Following fire disturbance, early-successional forests exhibit high availability of N relative to older stands (DeLuca et al. 2002; Wardle et al. 2003), despite a M. J. Gundale (&)  J. Sverker  M.-C. Nilsson  D. A. Wardle Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, 901 83 Umea ˚, Sweden e-mail: Michael.Gundale@svek.slu.se B. R. Albrectsen Umea ˚ Plant Science Centre, Department of Plant Physiology, Umea ˚ University, 901 87 Umea ˚, Sweden 123 Plant Ecol (2010) 211:253–266 DOI 10.1007/s11258-010-9787-9