Publicação
Searching for an ecological indicator based on plant functional diversity along a climatic gradient
| Resumo: | Searching for early indicators of climate change is of utmost importance in drylands, since these regions are particularly sensitive to desertification, due to water scarcity and land-use impacts. Our main objective was to search for a potential ecological indicator of climate change. For that, plant community was assessed along a spatial climatic gradient in a dryland area located in southern Portugal. Plant community was assessed in 15 sites that varied in mean annual precipitation (521-634mm) and mean annual temperature (16-17°C), in Mediterranean grasslands. Plant community was studied both in a classical approach (species diversity and plant cover) and in a functional approach (through the analysis of several a priori functional groups and measured traits related to climate) and related to climatic variables. The point-line intercept method was used to assess plant community. A priori functional groups were based on life form, life cycle and families. Traits measured were biomass, height and SLA. The sampled sites were dominated by annual grasses. Species richness and plant cover decreased significantly with increasing aridity. Considering a priori functional groups, the cover of hemicryptophytes decreased with increasing aridity, as well as cover of perennial grasses and annual legumes while cover of annual grasses remained unchanged. Along the climatic gradient, a community shift was found based on relative cover (relative % in the plant community): annual grasses and Plantaginaceae species increased their relative cover with increasing aridity, while perennial grasses, annual legumes and Caryophillaceae species decreased in relative cover. A multivariate analysis grouped species in a manner consistent with the previous result. Among a priori functional groups, the most promising groups with potential to be used as ecological indicators are perennial grasses and annual legumes and the previously mentioned community shift. Biomass and height changed along the climatic gradient, although the response pattern found for dominant species did not always match the response of their respective a priori functional groups. For example while height of annual grasses increased with precipitation, height of the dominant annual grass A. pourretti did not significantly changed. Specific leaf area, which was analyzed only for the Compositae species Tolpis barbata, decreased with increasing aridity as well. Considering that the height of this species also decreased, this suggests a change in the physiological performance along the climatic gradient. Moreover it reflects the phenotypic plasticity of this species. In sum, the response of specific traits (e.g. height or SLA) measured in the same species along the gradient seems to have the potential to be used as an ecological indicator of climate change, especially in species with global distribution. |
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| Autores principais: | Batista, Melanie Köbel, 1989- |
| Assunto: | Biodiversidade Ecologia vegetal Alterações climáticas Pastagens Montado Alentejo - Portugal |
| Ano: | 2012 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | Searching for early indicators of climate change is of utmost importance in drylands, since these regions are particularly sensitive to desertification, due to water scarcity and land-use impacts. Our main objective was to search for a potential ecological indicator of climate change. For that, plant community was assessed along a spatial climatic gradient in a dryland area located in southern Portugal. Plant community was assessed in 15 sites that varied in mean annual precipitation (521-634mm) and mean annual temperature (16-17°C), in Mediterranean grasslands. Plant community was studied both in a classical approach (species diversity and plant cover) and in a functional approach (through the analysis of several a priori functional groups and measured traits related to climate) and related to climatic variables. The point-line intercept method was used to assess plant community. A priori functional groups were based on life form, life cycle and families. Traits measured were biomass, height and SLA. The sampled sites were dominated by annual grasses. Species richness and plant cover decreased significantly with increasing aridity. Considering a priori functional groups, the cover of hemicryptophytes decreased with increasing aridity, as well as cover of perennial grasses and annual legumes while cover of annual grasses remained unchanged. Along the climatic gradient, a community shift was found based on relative cover (relative % in the plant community): annual grasses and Plantaginaceae species increased their relative cover with increasing aridity, while perennial grasses, annual legumes and Caryophillaceae species decreased in relative cover. A multivariate analysis grouped species in a manner consistent with the previous result. Among a priori functional groups, the most promising groups with potential to be used as ecological indicators are perennial grasses and annual legumes and the previously mentioned community shift. Biomass and height changed along the climatic gradient, although the response pattern found for dominant species did not always match the response of their respective a priori functional groups. For example while height of annual grasses increased with precipitation, height of the dominant annual grass A. pourretti did not significantly changed. Specific leaf area, which was analyzed only for the Compositae species Tolpis barbata, decreased with increasing aridity as well. Considering that the height of this species also decreased, this suggests a change in the physiological performance along the climatic gradient. Moreover it reflects the phenotypic plasticity of this species. In sum, the response of specific traits (e.g. height or SLA) measured in the same species along the gradient seems to have the potential to be used as an ecological indicator of climate change, especially in species with global distribution. |
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