Functional diversity of algal communities from headwater grassland streams: how does it change following afforestation?

CIBILS, L.; PRÍNCIPE, R.; MÁRQUEZ, J.; GARI, N.; ALBARIÑO, R.

AQUATIC ECOLOGY

SPRINGER

Lugar: Berlin; Año: 2015 vol. 49 p. 453 - 466

1386-2588

Pine afforestation of grassland streams may lead to changes in species traits and therefore functional diversity the epilithic algal community. Here we studied trait-based responses in three grassland and three afforested streams in a mountain watershed of Córdoba, Argentina. We hypothesized that afforestation would reduce functional diversity through a simplification of periphyton architecture resulting from reduction in light availability, and that changes in hydrological periods would influence community responses. Algal samples were collected at each stream during two different hydrological periods (high-flow and low-flow) and physicochemical variables were recorded. Selected traits included strategies and morphological characters related to resource access and disturbance resistance (size, morphological guild, resource requirement, attachment mechanism and life form). We calculated two indices of functional diversity, Rao´s quadratic entropy (FDQ) and functional variance. Most trait categories showed a significant effect of one or both factors; 26% discriminated between vegetation types, 26% reflect the changes between hydrological periods and 47% were sensitive to both of them. Our results revealed some categories of traits that can be used to distinguish changes in riparian vegetation, such as unicellular life form and high profile guild. Functional diversity of single traits was affected differently by pine afforestation. However the most integrative index, the FDQ mean, partially supported our hypotheses. Afforestation reduced FDQ mean by 50%, but only during low-flow period. FDQ mean was high and similar between streams at high flow, when environmental factors, such as discharge and temperature, could prevail on differences in riparian vegetation.