PROJECT DESCRIPTION
BACKGROUND
Alder (Alnus glutinosa) forests commonly grow on the banks of rivers with permanent water flows. This habitat is at its optimum in the middle of river courses. Past human activity has led to a reduction of many alder forests and much of this habitat is now limited to thin rows of trees located in single linesdirectly at the riparian edge. The degradation and fragmentation of this habitat, listed in the Habitats Directive as the priority habitat Alluvial forests with Alnus glutinosa and Fraxinus excelsior (Alno-Padion, Alnion incanae, Salicion albae), threatens a range of characteristic invertebrate species.
OBJECTIVES
The objective of the ECOTONE project was the conservation of alder alluvial forests in two Portuguese rivers, in order to increase the populations of three species of dragonfly (Oxygastra curtisii, Gomphus graslinii and Macromia splendens). The project also aimed to improve the conservation status of two species of freshwater pearl mussels (Margaritifera margaritifera and Unio crassus). It aimed to conceive, implement and evaluate active management methodologies targeting improvements to alluvial forests supporting alder and ash (Fraxinus excelsior). Forest management methodologies would be tailored to support the conservation status of endangered freshwater pearl mussel populations. Several ex-situ reproduction techniques would be used to increase the mussel populations and to reinforce the populations of fish that are host to these mussel species.
RESULTS
The ECOTONE project restored alluvial alder forest habitats through the improvement of riparian natural vegetation and the removal of obstacles along watercourses, in two Natura 2000 sites on an area of over 15 ha. The project beneficiaries designed, implemented and evaluated methods for the management of riverside forests, in particular the Habitats Directive priority habitat Alluvial forests with Alnus glutinosa and Fraxinus excelsior (Alno-Padion, Alnion incanae, Salicion albae), to increase dragonfly populations and improve the conservation status of freshwater mussels. In parallel, captive breeding techniques increased freshwater mussel populations (Margaritifera margaritifera and Unio crassus), while reinforcement actions were carried out for host populations of both species: brown trout (Salmo trutta) and Mira chub (Squalius torgalensis), respectively.
The project was carried out in sections of two waterways in Natura 2000 sites with different characteristics: the Rio Paiva SCI, a perennial water course with well-oxygenated water, and the Costa Sudoeste SCI, where the Torgal stream has a highly variable flow, both between seasons and years, giving it a temporary water regime.
Overall, the project achieved all its proposed objectives, apart from the reinforcement of brown trout populations. However, the problems were identified, and a new and successful protocol was drafted within the projects scope, which is now successfully followed by fish breeding centres. In addition, the beneficiaries produced new regulations and management documents, a habitat management recommendations booklet, three project impact assessment reports for Odonata (dragonflies and damselflies), ichthyofauna (fish) and naiads (nymphs of aquatic insects). The project team also demonstrated bioengineering solutions to restore river banks, while three fishing concessions were certified with new regulation to protect brown trout populations.
Regarding field conservation tasks, the project restored 15.1 ha of priority Alluvial forests habitat in the two sites, with an increase in habitat area of approximately 4.5 ha. The project team cleared 0.8 ha of riverbed areas, with the aim of removing obstacles to regular water flow to preserve characteristic dynamic processes in watercourses. They cleared and managed natural riparian forest, including the removal of invasive plants, on 18.8 ha; planted 13 066 native trees and bushes (e.g. Alnus glutinosa, Fraxinus angustifolia, Salix atrocinerea, Salix salviifolia and Frangula alnus); reconnected 2.5 ha of old riverbeds; stabilised 800 m of river banks, built two impoundments in the Torgal stream, and increased river habitat by 2 ha.
The project team bred 161 178 juveniles of Margaritifera margaritifera, and infested 373 brown trout that were introduced into the River Paiva (a total of about 12 104 mussel juveniles released); and bred 12 104 juveniles of Unio crassus and infesting 179 Mira chub that allowed three reintroductions to be carried out in the Torgal stream (in total 12 400 juveniles released). Two reintroductions of Mira chub were carried out, in which a total of 986 fish were released. A new protocol was implemented for capturing and breeding brown trout in the River Paiva sub-basin. Furthermore, the project team created a licensed fishing area and changing the regulations for two existing areas, to improve the management of brown trout populations. They also carried out two population control actions for alien invasive species, specifically the red swamp crawfish (Procambarus clarkii) and common sunfish (Lepomis gibbosus)./p>
The engineering measures applied in the correction of the river beds and banks have a high demonstration value. These measures were presented and discussed in the project workshop and with representatives of other projects that visited the project area.
The project team have developed successful public awareness campaigns that directly involve the municipalities in the continuity of the project tasks. The involvement of those municipalities and of NGOs in the future management of the fish reproduction centres will ensure the sustainability of those centres, which are key factors in the preservation of the target species populations. The direct involvement of the fishing sector in the conservation of the fish resources is also an important aspect of the project.
Further information on the project can be found in the project's layman report and After-LIFE Conservation Plan (see "Read more" section).
