Are above and belowground functional syndromes coupled across different species? An empirical test in the subtropical seasonally dry forests of central Argentina

XIMENA A. BROIERO; ESTEBAN KOWALJOW; GEORGINA CONTI

Pirenópolis

Congreso; 59th Symposium of the IAVS; 2016

International Association of Vegetation Science (IAVS)

The functional approach has proved to be a powerful framework to analyze relationships between abiotic factors, community functional composition and ecosystem processes. Across contrasting floras, it has been extensively evidenced the existence of a leaf economic spectrum (LES) given by the association between leaf traits values, and reflecting a fundamental trade-off between plant resource acquisition and conservation. Although the existence of this trade-off have been mainly reported in studies focused on leaves, it have been hypothesized the existence of an integrated whole-plant strategy, including stem and roots tissues. In the present work, we examined the relationship between 16 above and belowground functional traits from 5 species (including trees, shrubs and grasses) in the subtropical seasonally dry Chaco forests of Argentina, to test (i) if the widely supported LES also exists for root traits values (RES), and (ii) if they are coordinated, defining a whole-plant economic spectrum. We found significant differences between species in almost all traits, revealing the differential occupation of functional space in the economic spectrum. Aboveground traits values showed different orthogonal axis for structural and leaf traits, which follow the LES, as expected. Across the LES, the C4 grass was in the most acquisitive extreme, while the C3 grass occupied the most conservative extreme. Regarding roots traits, we did not find a clear economic continuum, in comparison with the LES, where specific root length and nitrogen root content followed opposite directions in the multivariate distribution. Across the multivariate space, belowground traits showed higher variation, with no clear position across a single axis. Although most individual pairs of associated leaf and root traits showed univariate coordination, chemical traits did not show significant relationships across leaf and root tissues, and so the LES and RES were weakly coupled across the sampled species. Our results indicate that other ecosystem processes could drive functional diversity and resource use belowground, where soil matrix is complex and spatially heterogeneous. The extent to which above and belowground functional strategies are coordinated is important to understand plant species distributions and functioning and so, the impacts of land-use and climate change on ecosystem processes and services.