Albano Figueiredo

Would Rainfed Agriculture Be the Right Option Under Climate Change Scenarios? A Case Study from Centro Region of Portugal

Agriculture has changed significantly during the last 30 years in Portugal. One of the main changes is related to agricultural abandonment, mainly driven by demographic dynamics on areas that are marginal in terms of productivity. Such trend affects mainly rainfed agriculture, and was significant in the inland Norte and Centro regions of Portugal between 1990 and 2010. By contrast, irrigated areas dedicated to agriculture are increasing. Considering a predicted reduction on water availability under future climatic scenarios, determined by the decrease in the amount of annual precipitation, it is necessary to set strategies to adapt agriculture to a new climatic context, considering both production and consumption/dietary trends. To do so, and using as case study the Centro Region of Portugal, this work aims to evaluate how the suitable area for agriculture might change under future climatic scenarios (RCP 4.5 and 8.5 scenarios for the two time-windows of 2041–2070 and 2071–2100), and identify measures that contribute to adapt agriculture to a new context. Such assessment is based on a modelling approach that aims to evaluate suitability to agriculture, which is set from soil properties (soil type and texture), topographic parameters (such as slope and land morphology), and climatic conditions (water deficit). The expected reduction on water availability under future climatic scenarios, combined with recent trends on agriculture, namely the reduction of rainfed agriculture and the increase of irrigated agriculture areas, points to an unsustainable situation. This is of great concern, once there is a match between areas where water deficit is predicted to increase more and areas where irrigated area is expanding today. Thus, specific adaptation strategies/policies are needed to revert/cope with such trends, which must be spatially explicit and locally meaningful. The implementation of such approaches might be oriented by results from assessment of predicted changes in terms of suitable area for agriculture, but also consider economic and dietary aspects, an exercise that we try to validate based on the conditions of the Centro Region of Portugal.

Complex cytogeographical patterns reveal a dynamic tetraploid–octoploid contact zone

Cytotype distribution patterns are crucial for evaluating ecological processes involved in polyploid establishment and evolution. We explore cytotype diversity and distribution in contact zones of a tetraploid–octoploid plant. Complex contact zones and high cytogenetic diversity in natural populations were observed. Tetraploids and octoploids show geographical separation and habitat similarity suggesting that mixed-ploidy populations are subject to frequency-dependent selection, although the existence of reproductive barriers may enable cytotype coexistence. The detection of hexaploids in different points of the distribution indicates that unreduced gamete formation and hybridization occur and might be involved with recurrent polyploid formation and gene flow between cytotypes.

Current and potential distribution for Acacia Mill. species (Fabaceae) on Madeira Island and impacts on plant diversity after invasion

The most common species of Acacia Miller on Madeira Island were introduced during the 19th and 20th century, usually as ornamental or on afforestation processes, and became invaders. This article aims to i) assess current distribution of Acacia’s species at Madeira Island, ii) evaluate the impacts on plant diversity after invasion, comparing phytosociological relevees from Acacia communities to native climax communities; iii) model their potential distribution, supported on species distribution modelling, based on a correlative approach; and iv) confirm the invasiveness of Acacia mearnsii, assessing the historical evolution using RLPT (Repeat Landscape Photography Technique). Data collection for current distribution was based on field survey, and guided by a systematic and stratified sampling approach, set to ensure that the entire environmental gradient of the island was sampled. As results, the communities of Acacia are characterized by very low species diversity, are usually monospecific at the tree layer, and present a scarce abundance of native and endemic taxa. In terms of potential distribution, just the higher altitudes of the island are predicted as unsuitable to A. melanoxylon and A. mearnsii. But some precaution must be taken on reading such results, once current species’ absence may not be connected to ecological determinants, but related to its recent introduction. Besides, the landscape historical evolution assessment puts on evidence the invasiveness of Acacia mearnsii, mainly because of its current presence on areas were deliberate introduction is not plausible. According to the results, namely the extensive suitable areas and extremely poor communities in terms of plant diversity, the species under focus can be considered as very problematic invaders.https://doi.org/10.14195/0871-1623_35_6The most common species of Acacia Miller on Madeira Island were introduced during the 19th and 20th century, usually as ornamental or on afforestation processes, and became invaders. This article aims to i) assess current distribution of Acacia’s species at Madeira Island, ii) evaluate the impacts on plant diversity after invasion, comparing phytosociological relevées from Acacia communities to native climax communities; iii) model their potential distribution, supported on species distribution modelling, based on a correlative approach; and iv) confirm the invasiveness of Acacia mearnsii, assessing the historical evolution using RLPT (Repeat Landscape Photography Technique). Data collection for current distribution was based on field survey, and guided by a systematic and stratified sampling approach, set to ensure that the entire environmental gradient of the island was sampled. As results, the communities of Acacia are characterized by very low species diversity, are usually monospecific at the tree layer, and present a scarce abundance of native and endemic taxa. In terms of potential distribution, just the higher altitudes of the island are predicted as unsuitable to A. melanoxylon and A. mearnsii. But some precaution must be taken on reading such results, once current species’ absence may not https://doi.org/10.14195/0871-1623_35_6 Cadernos de Geografia 68 Albano Figueiredo, Aida Pupo-Correia, António Campar Almeida e Miguel Menezes de Sequeira