Ramos A.,University of Lisbon |
Pereira M.J.,University of Lisbon |
Soares A.,University of Lisbon |
Rosario L.D.,ICNF Instituto da Conservacao da Natureza e das Florestas |
And 6 more authors.
Agricultural and Forest Meteorology | Year: 2015
In temperate areas, vegetation seasonality and phenology have been mostly associated with temperature changes both in space and time. In drylands, where water is the most limiting factor, we expect that they strongly respond to water availability. The degree to what that response depends more on precipitation that occurred when vegetation seasonality and phenology were measured, or on the long-term precipitation, is not fully known. We hypothesize that in drylands, long-term precipitation better explains the patterns of seasonality and phenology metrics than concurrent one, due to constrains imposed by ecosystem legacy. We correlated long-term precipitation (30 years normal) and concurrent precipitation (12 years) to several seasonal metrics (MODIS, average of 12 years) measured in a savannah-like system, Mediterranean evergreen woodlands, located in southwest Europe (Portugal). We observed that seasonal metrics of productivity and phenology were more significantly related with long-term precipitation than with concurrent precipitation. Comparing the extremes of our gradient we found that drier areas (c. 496. mm long-term annual precipitation) showed average growth cycles of annual plants 25 days shorter and ended 16 days sooner than more rainy regions (c. 739. mm). Evergreen vegetation productivity was shown to be c. 30% lower in drier areas. Moreover, productivity and phenology metrics were non-linearly related to the long-term precipitation, suggesting both are particularly constrained below 600-650. mm. These results suggest a memory effect in the response of vegetation to climate, most probably associated to legacies on soil characteristics and on plant community. It also indicates the existence of ecosystem response thresholds in vegetation's response to precipitation along ecosystem transitions. Overall, this method can be used to track ecosystem services over space in drylands and for managing ecosystems for both mitigation and adaptation to climate change. © 2014 Elsevier B.V. Source
M. Martins G.,3nter for Ecology |
M. Martins G.,University of The Azores |
Hipolito C.,3nter for Ecology |
Hipolito C.,University of The Azores |
And 8 more authors.
Marine Environmental Research | Year: 2016
In many coastal regions, vegetated habitats (e.g. kelps forests, seagrass beds) play a key role in the structure and functioning of shallow subtidal reef ecosystems, by modifying local environmental conditions and by providing food and habitat for a wide range of organisms. In some regions of the world, however, such idiosyncratic ecosystems are largely absent and are often replaced by less notable ecosystem formers. In the present study, we empirically compared the structure and functioning of two distinct shallow-water habitats present in the Azores: one dominated by smaller frondose brown macroalgae (Dictyotaceae and Halopteris) and one dominated by low-lying turfs. Two replicated areas of each habitat were sampled at two different times of the year, to assess spatial and temporal consistency of results. Habitats dominated by small fronds were significantly (ca. 3 times) more productive (when standardized per algal mass) compared to the turf-dominated habitats, and supported a distinct assemblage (both in terms of composition and abundance) of associated macrofauna. Unlike other well-known and studied vegetated habitats (i.e. kelp forests), however, no effects of habitat were found on the structure of benthonic fish assemblages. Results were spatially and temporally consistent suggesting that, in warmer temperate oceans, habitats dominated by species of smaller frondose brown algae can also play an important role in the structure and functioning of subtidal communities and may, to a certain extent, be considered analogous to other well-known vegetated habitats around the world (i.e. kelp forests, seagrass beds). © 2016 Elsevier Ltd Source