Austral Ecology (2005) 30, 789–796 *Corresponding author. Accepted for publication May 2005. Linking plant functional traits with post-fire sprouting vigour in woody species in central Argentina DIEGO E. GURVICH,* LUCAS ENRICO AND ANA M. CINGOLANI Instituto Multidisciplinario de Biología Vegetal, FCEFyN (CONICET-Universidad Nacional de Córdoba), CC 495 (5000) Córdoba, Argentina (Email: dgurvich@com.uncor.edu) Abstract Sprouting vigour is determined by the plant amount of reserves and intrinsic growth rate of plants. While the first factor has been well studied, the second is far less understood. Although a higher growth rate would imply a higher sprouting vigour, fast-growing species may have less below-ground reserves, and thus, a lower sprouting potential. The relative importance of both opposite effects was little explored in the literature. To analyse the influence of growth rate on sprouting vigour, one growth season after a fire we measured plant height of the old (pre-fire) and new (post-fire) tissue in 194 individuals of 14 woody species from a woodland in central Argentina. We calculated a mean value of pre- and post-fire height for each species, and obtained from a data- base potential height at maturity, wood density (WD) and specific leaf area (SLA), as surrogates of intrinsic growth rate. We performed a forward stepwise multiple regression using WD and SLA, together with mean pre-fire height or potential height as independent variables, and mean post-fire height (as an indicator of resprout vigour) as the dependent variable. Interactions were also tested. Pre-fire height, WD and their interaction term were the variables that best explained post-fire height. We also analysed the relationship between pre- and post-fire size for each species independently by fitting hyperbolic functions. Then we correlated both parameters of the functions to species characteristics (WD, SLA, potential height and mean pre-fire height). Both parameters of the hyperbolic functions were significantly correlated only with WD, but not with the other species characteristics. All results together indicate that species with low WD (i.e. high potential growth rate) regrow more vigorously than species with high WD when pre-fire individuals were tall. In contrast, when pre-fire individuals were small, WD had no influence on sprout vigour. A trade-off between allocation of biomass to underground reserves and shoot growth seems to be responsible for the patterns obtained. For small individuals, below-ground reserves seem to play a more important role than inherent growth rate (here measured through WD) in determining the sprouting vigour, while for large individuals, growth rate seems more important than reserves. Key words: fire ecology, growth rate, specific leaf area, sprouting vigour, wood density. INTRODUCTION Plants can be classified as seeders and sprouters according to their recovery strategy after intense dis- turbance such as fire, windstorms, drought, flooding, herbivory and landslides, as well as anthropogenic disturbance such as forest clearing (Whelan 1995; Bellingham & Sparrow 2000; Bond & Midgley 2001; Pausas et al. 2004). The trade-offs between these strat- egies are well known. Seeders are fast-growing, allo- cate more resources to reproduction and exhibit early maturation and high seedling survival. In contrast, sprouters generally have fewer seeds, smaller seed banks, slower growth and maturation rates, and almost always have relatively few seedlings and poor seedling survival (Keeley & Zedler 1978; Bellingham & Spar- row 2000; Bond & Midgley 2001; Pausas et al. 2004). Among sprouters, the extent of below-ground reserves has been viewed as the main determinant of sprouting vigour, particularly when disturbance elim- inate all the above-ground biomass (Malanson & Trabaud 1988; Pate et al. 1990; Canadell & López- Soria 1998; Bell & Ojeda 1999). However, less atten- tion has been paid to the effects of plant intrinsic growth rate, which is related to the rate at which reserves are allocated after a disturbance (Chapin et al. 1990; Kobe 1997; Cruz et al. 2002). In this way, intrinsic growth rate can influence sprouting vigour and hence the competitive balance among species, and finally, community dynamics and composition (Bond & Midgley 2001). Specific leaf area (SLA) and wood density (WD) are both functional traits strongly related to plant intrinsic growth rate (Garnier 1992; Castro-Díez et al. 1998; Roderick & Berry 2001; Vendramini 2004), since they summarize fundamental trade-offs between allocation to growth or to defence and reserves (Chapin et al. 1993). For this reason they are