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Influence of forest and riparian connectivity on biodiversity in the Mediterranean region

Mª Rosário Fernandes, Gonçalo Duarte, André Fonseca, Vera Zina, Sofia Conde, Manuela Branco, José Carlos Franco, Pedro Segurado e Mª Teresa Ferreira

Forest Research Centre, School of Agronomy, University of Lisbon, Tapada da Ajuda, 1349-017 Lisbon, Portugal

Forest and riparian ecosystems are considered fundamental for the maintenance of biodiversity, goods and services. However, global changes have led to the loss of natural spaces that serve as habitat and ecological corridors for several biological communities, leading to a generalized loss of connectivity and biodiversity, with effects at the local and landscape scales.

In order to reverse this situation, the CERES project intends to develop actions to maintain and optimize ecological connectivity, aiming to improve biodiversity and ecological functions, and promoting animal and plant species movements. Within this context, CERES partners have been developed a common methodology for connectivity analysis, applied to the different contexts and scales of SUDOE, for the characterization and identification of landscape elements, that means, natural and semi-natural forest and /or riparian habitats, considered essential for the maintenance of global connectivity, referred as Ecological Relevant Units (ERU).

Although the benefits of ERUs in intensive production systems, such as agricultural systems, are unequivocal, little is known about the effects of their typology, size and spatial configurations in the provision of ecosystems services and biodiversity. In addition, the importance of the distinct ERUs classes in other production systems, such as forests or agro-forestry systems, is still unknown.

Portugal represents the Mediterranean ecoregion in the CERES consortium, with two case studies located in Tagus basin, the Sorraia and Almonda. The two areas have distinct land use matrices: an intensive agricultural production system dominated by irrigated croplands, a forest production system characterized by eucalyptus and pine forests, and an agroforestry system dominated by cork oak and holm oak trees.

The project started with the production of the maps of the Ecological Relevant Units in the two study areas. The maps were obtained through the visual classification of the ERU patches using high spatial resolution aerial images, and validated by field campaigns. ERUs were classified by taking into account the dominant ecosystem where they are located (riparian ecosystem or forest ecosystem) and the dominant strata (woody or herbaceous) (Figure 1). A total of 1709 ERUs were obtained in the two study areas. In the agricultural landscape matrix a higher number of forest ERU patches were observed when compared with the riparian ERU patches. Nevertheless, the riparian ERU patches were larger and more complex than the forest ones. As for the forestry and agro-forestry production system, only riparian ERU patches were identified, although in the eucalyptus area the riparian ERU patches are larger, which is likely to be related with greater water availability.

Figura 1 – Classification system and map of the ERUs for the distinct landscapes at the two study areas in Portugal

In a second phase of the project, which took place between March and July 2019, several sampling campaigns were carried out to collect information related to biodiversity and the potential provision of ecosystem services, associated with each EFA type under study. For this, ants and bats were used as biodiversity indicators while artificial caterpillars were used as indicators of the predation service. A total of 200 sites were sampled during 90 days of field work, distributed in a similar way among the three landscape matrices, which translate into around 1500 pitfalls, over 1100 dummy caterpillars and more than 4 million acoustic records for the bat group. The sampling sites were selected in order to cover the different EFA classes but also the distinct matrices (agricultural system, production forest, and agro-forestry system), which was only possible thanks to the collaboration of agricultural and forest producers of the two study areas.

The project is now in the phase of biological data analysis, which includes laboratory analysis, species identification and acoustic recognition. During this year, we intent to developed the predictive model that will relate the ERU connectivity and spatial configurations with the various biodiversity and ecosystem services indicators, in order to propose practical measures for the conservation and restoration of habitats for different target-species.

The results and the methodology have been shared with the whole partnership in order to be enriched by their experience and knowledge.

The CERES partners will apply the common method for characterising connectivity and ecological quality to several pilot areas in the SUDOE region. These areas range from a few thousand hectares (8,900 ha. in Almonda in Portugal) to several hundred thousand hectares (193,000 ha. in the Cévennes in France) depending on the target species that have been chosen to carry out the analysis (ants, bats, brown bears, etc.).

Here are the CERES pilot areas :

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