Coastal vegetation zonation and dune morphology in some Mediterranean ecosystems

This paper describes the vegetation zonation and its relationship with dune local morphology through the application of a randomization test on some sandy ecosystems of the Italian Mediterranean coast. We postulate that the slope and the aspect of sand dunes are essential variables in the analysis of a correct plant community position along the sea-inland vegetation gradient. This study presents an analysis of coastal vegetation zonation in some of the best preserved sites of the Lazio coast (central Italy). Analysis of variance with randomization testing was performed in order to establish whether community differences are related to slope and aspect. Results from vegetation transects showed that complete community sequence is lacking in the study area. Although some community types are very common and widespread, others are rare and only restricted to areas with well-preserved dune ridges. Regarding slope/aspect, the randomization test shows that only community types located in both extremes of the vegetation zonation revealed significant differences while no differences were found for rare or heavily disturbed communities

Coastal vegetation zonation and dune morphology in some Mediterranean ecosystems

This paper describes the vegetation zonation and its relationship with dune local morphology through the application of a randomization test on some sandy ecosystems of the Italian Mediterranean coast. We postulate that the slope and the aspect of sand dunes are essential variables in the analysis of a correct plant community position along the sea–inland vegetation gradient. This study presents an analysis of coastal vegetation zonation in some of the best preserved sites of the Lazio coast (central Italy). Analysis of variance with randomization testing was performed in order to establish whether community differences are related to slope and aspect. Results from vegetation transects showed that complete community sequence is lacking in the study area. Although some community types are very common and widespread, others are rare and only restricted to areas with well-preserved dune ridges. Regarding slope/aspect, the randomization test shows that only community types located in both extremes of the vegetation zonation revealed significant differences while no differences were found for rare or heavily disturbed communities

Dinâmica vegetacional em pastagem natural submetida a tratamentos de queima e pastejo Vegetation dynamics of natural grassland under treatments of burning and grazing

Foram avaliados durante três anos os efeitos de tratamentos de fogo e pastejo sobre a dinâmica da vegetação de uma pastagem natural localizada em Santa Maria, na região da Depressão Central, Rio Grande do Sul. Foi considerada a hipótese de resiliência, resultado das espécies componentes da pastagem terem evoluído sob influência de tais distúrbios. O experimento foi composto por oito parcelas experimentais submetidas a combinações de níveis de pastejo (pastejado, excluído) e de fogo (queimado, não-queimado), em duas posições de relevo (encosta, baixada). A análise multivariada dos dados de composição de espécies foi baseada em ordenação e testes de aleatorização. A vegetação sob efeito de pastejo, independente da queima, apresentou trajetórias direcionais, enquanto sob exclusão as trajetórias foram caóticas. O efeito do pastejo parece ser determinante da dinâmica vegetacional (P=0,077).<br>The effect of fire and grazing treatments on vegetation dynamics was evaluated during three years on a natural grassland located in Santa Maria, in the region of "Depressão Central", Rio Grande do Sul, Brazil. A hypothesis of resilience resulting from the fact that the species of the grassland evolved under the influence of these disturbances was considered. The experimental setup was formed by eight plots subjected to combinations of grazing (grazed, ungrazed) and fire (burned, unburned) levels, on two relief positions (convex, concave slope). Multivariate analysis of compositional data used ordination and randomization testing. Vegetation under grazing tended to show directional trajectories of floristic composition change, while under grazing exclusion the trajectories could be considered chaotic, independently from the plots being burned or not. Grazing effect seems to be determinant of vegetacional dynamics (P=0.077)