The acquisitive-conservative axis of leaf trait variation emerges even in homogeneous environments

The acquisitive-conservative axis of plant ecological strategies results in a pattern of leaf trait covariation that captures the balance between leaf construction costs and plant growth potential. Studies evaluating trait covariation within species are scarcer, and have mostly dealt with variation in response to environmental gradients. Little work has been published on intraspecific patterns of leaf trait covariation in the absence of strong environmental variation. Methods: We analysed covariation of four leaf functional traits [specific leaf area (SLA) leaf dry matter content (LDMC), force to tear (Ft) and leaf nitrogen content (Nm)] in six Poaceae and four Fabaceae species common in the dry Chaco forest of Central Argentina, growing in the field and in a common garden. We compared intraspecific covariation patterns (slopes, correlation and effect size) of leaf functional traits with global interspecific covariation patterns. Additionally, we checked for possible climatic and edaphic factors that could affect the intraspecific covariation pattern. Key Results: We found negative correlations for the LDMC-SLA, Ft-SLA, LDMC-Nm and Ft-Nm trait pairs. This intraspecific covariation pattern found both in the field and in the common garden and not explained by climatic or edaphic variation in the field follows the expected acquisitive-conservative axis. At the same time, we found quantitative differences in slopes among different species, and between these intraspecific patterns and the interspecific ones. Many of these differences seem to be idiosyncratic, but some appear consistent among species (e.g. all the intraspecific LDMC-SLA and LDMC-Nm slopes tend to be shallower than the global pattern). Conclusions: Our study indicates that the acquisitive-conservative leaf functional trait covariation pattern occurs at the intraspecific level even in the absence of relevant environmental variation in the field. This suggests a high degree of variation-covariation in leaf functional traits not driven by environmental variables.

Fil: Gorne, Lucas Damián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina

Fil: Díaz, Sandra Myrna. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentina

Fil: Minden, Vanessa. Vrije Unviversiteit Brussel; Bélgica. Universität Oldenburg; Alemania

Fil: Onoda, Yusuke. Kyoto University. Graduate School of Agriculture. Division of Forest and Biomaterials Science; Japón

Fil: Kramer, Koen. Wageningen University; Países Bajos

Fil: Muir, Christopher. University of Hawaii at Manoa; Estados Unidos

Fil: Michaletz, Sean T.. University of British Columbia; Canadá

Fil: Lavorel, Sandra. Centre National de la Recherche Scientifique; Francia

Fil: Sharpe, Joanne. Edgecomb Eddy School; Estados Unidos

Fil: Jansen, Steven. Universitat Ulm; Alemania

Fil: Slot, Martijn. Smithsonian Tropical Research Institute; Estados Unidos

Fil: Chacon, Maximiliano Eduardo. Universidad de Costa Rica; Costa Rica

Fil: Boenisch, Gerhard. Max Planck Institute For Biogeochemistry; Alemania