Angela Lomba

Endemic Sand Dune Vegetation of the Northwest Iberian Peninsula: Diversity, Dynamics, and Significance for Bioindication and Monitoring of Coastal Landscapes

Abstract Coastal areas are sensitive systems suffering both natural and anthropic pressures. Specifically, coastal sand dune dynamics is related with observable modifications in plant communities, and this relationship is being pointed out in recent years as a monitoring tool in littoral areas. Plant community types, with a relatively stable floristic composition related to specific ecologic conditions (“plant associations”), provide a suitable tool for bioindication within monitoring processes and in the management of littoral areas. In this regard, recent bio-geologic studies performed in dune systems of Southwest Europe allowed the identification of a number of specific bioindicators for both mobile and interior dunes. In Northwest Iberian Peninsula, sand dune vegetation is distinguished by its transitional character between typical Atlantic and Mediterranean vegetation types, and its originality is still enhanced by the occurrence of narrow endemic species and by the fact that most vegetation types are endemic to the territory. The organisation of these community types within dune systems is strongly determined by specific dynamic processes mediated by both natural and anthropic disturbances, so they present a large potential for bioindication of coastal dynamics and conservation status. In this paper, the most significant ecologic, floristic and biogeographic characters of sand dune vegetation in Northwest Iberian Peninsula are discussed with the purpose of demonstrating the usefulness of well-defined vegetation types for bioindication within the context of both short- and long-term monitoring of coastal sand dune systems.

Simulating long-term effects of abandonment on plant diversity in Mediterranean mountain farmland

In this paper, long-term impacts of meadow abandonment scenarios on plant diversity were forecasted for high nature value farmland in northern Portugal, and implications for conservation planning and agri-environmental management are addressed. Vegetation patches representative of forests, meadows and edges, on mesic and wet soils, were surveyed for vascular plant diversity. Species richness and composition were compared across vegetation types, and additive partitioning was used to quantify hierarchic components of species richness. The implications of total and partial meadow abandonment were simulated according to landscape outcomes predicted for each scenario, and confirmed with a Monte-Carlo resampling. Forests hosted the highest number of species, as well as of exclusive species. Nonetheless, from the total pool (213), 21.6% were exclusive to meadows. Vegetation types generally shared small proportions of their species pools. With total meadow abandonment, a drastic decrease in total species richness (41.1%) and in endemic species richness (loss of 20.8%) was forecasted. However, only 12.3% of all species were forecasted to disappear under scenarios of partial abandonment. Landscape-level plant diversity can, therefore, be maintained by promoting farmland mosaics, even if the loss of scattered meadows in favour of native forests could be acceptable. Agri-environmental schemes should thus prioritize the maintenance of landscape heterogeneity.

Using life strategies to explore the vulnerability of ecosystem services to invasion by alien plants

Invasive plants can have different effects on ecosystem functioning and on the provision of ecosystem services, with the direction and magnitude of such effects depending on the service and ecosystem being considered, but also on the life strategies of the invaders. Strategies can influence invasiveness, but also key processes of host ecosystems. To address the combined effects of these various factors, we developed a methodological framework to identify areas of possible conflict between ecosystem services and alien invasive plants, considering interactions between landscape invasibility and species invasiveness. Our framework combines multi-model inference, efficient techniques to map ecosystem services, and life strategies. The latter provides a functional link between invasion, functional changes, and potential provision of services by invaded ecosystems. The framework was applied to a region in Portugal, for which we could successfully predict current patterns of plant invasion, of ecosystem service provision, and of potential conflict between alien species richness and the potential provision of selected services. Potential conflicts were identified for all combinations of plant strategy and ecosystem service, with an emphasis on carbon sequestration, water regulation, and wood production. Lower levels of conflict were obtained between invasive plant strategies and the habitat for biodiversity supporting service. The value of the proposed framework for landscape management and planning is discussed with emphasis on anticipation of conflicts, mitigation of negative impacts, and facilitation of positive effects of plant invasions on ecosystems and their services.

Can we predict habitat quality from space? A multi-indicator assessment based on an automated knowledge-driven system

Abstract There is an increasing need of effective monitoring systems for habitat quality assessment. Methods based on remote sensing (RS) features, such as vegetation indices, have been proposed as promising approaches, complementing methods based on categorical data to support decision making. Here, we evaluate the ability of Earth observation (EO) data, based on a new automated, knowledge-driven system, to predict several indicators for oak woodland habitat quality in a Portuguese Natura 2000 site. We collected in-field data on five habitat quality indicators in vegetation plots from woodland habitats of a landscape undergoing agricultural abandonment. Forty-three predictors were calculated, and a multi-model inference framework was applied to evaluate the predictive strength of each data set for the several quality indicators. Three indicators were mainly explained by predictors related to landscape and neighbourhood structure. Overall, competing models based on the products of the automated knowledge-driven system had the best performance to explain quality indicators, compared to models based on manually classified land cover data. The system outputs in terms of both land cover classes and spectral/landscape indices were considered in the study, which highlights the advantages of combining EO data with RS techniques and improved modelling based on sound ecological hypotheses. Our findings strongly suggest that some features of habitat quality, such as structure and habitat composition, can be effectively monitored from EO data combined with in-field campaigns as part of an integrative monitoring framework for habitat status assessment.

Plant species segregation in dune ecosystems emphasises competition and species sorting over facilitation

Background: Coastal dunes are dynamic ecosystems, with vegetation seen as a key element in the response to a continuously changing environment. Aims: We explored co-occurrence patterns of plant species within dune ecosystems along a regional climatic and a local sea–inland gradient. Methods: Five habitat types were surveyed along a sea–inland transect at seven sites along a climatic gradient in Portugal. A multistep framework, considering the relevant scales and gradients, provided standardised scores of species co-occurrence (based on presence/absence and abundance data) for the whole study area and along the climatic and sea–inland gradients. Results: Species diversity was primarily related to the local sea–inland gradient. Co-occurrence analyses indicated the prevalence of species segregation, suggesting competition and species sorting across sites. Within each site, segregation prevailed, but tendencies for species aggregation were observed in some habitat types. Conclusions: To our knowledge, this is the first study evaluating species co-occurrences considering all habitat types within the whole dune ecosystem, analysing presence/absence and abundance data against regional and local gradients. Results converge with refined theories of community assembly, constituting added values for assessing multiscalar co-occurrence patterns of plant communities, and thus improving reporting of the condition of dune habitats and biodiversity.