PROJECT TITLE: ECOTONE – Management of riparian habitats towards the conservation of endangered invertebrates
DURATION: 2012-2013-2014-2015 (FOUR YEARS)
The project’s main goal is to conceive, implement and evaluate active management methodologies in the priority habitat — 91E0 *Alluvial forests with Alnus glutinosa and Fraxinus excelsior (Alno-Padion, Alnion incanae, Salicion albae) – in order to increase odonata populations (Oxygastra curtisii, Gomphus graslinii and Macromia splendens) and to improve the conservation status of endangered naiad populations (Margaritifera margaritifera and Unio tumidiformis (=Unio crassus)). Several ex-situ reproduction techniques will be used simultaneously, so as to increase the naiad populations (Margaritifera margaritifera and Unio tumidiformis (=Unio crassus)) and to reinforce the populations of fish that are host to these species (Salmo trutta and Squalius torgalensis, respectively).
The project will be carried out in branches of two rivers with different characteristics, located in the SCI “Rio Paiva” (PTCON0059) and “Costa Sudoeste” (PTCON0012). These two locations will undergo different approaches, according to its specific characteristics: the Paiva river has a continuous water flow, with well oxygenated waters; the Torgal stream presents various water flow patterns, according not only to the season of the year, but also to variations throughout the years, which contribute to a temporary hydrological regime.
Alder forests (Alnus glutinosa) settle in general on the banks of the rivers with permanent water flows, with more or less rapid current velocity (lotic facies) or otherwise, more locally, in slow currents (lentic facies). They are mostly absent from temporary water courses with prominent torrential regime and, therefore, this habitat has its phytosociological optimum on the middle of the river courses, where there are oligotrophic and mesotrophic waters and siliceous soils. These floristic formations are composed mainly of: an arboreous strata of Alnus glutinosa, Fraxinus angustifolia and Salix atrocinerea; a shrub strata of thorny shrubs, such as Crataegus monogyna, and non- thorny shrubs, such as Salix salviifolia subsp. salviifolia, Frangula alnus and Sambucus nigra, lianas – Bryonia dioica subsp. cretica, Hedera helix s.l., Tamus communis and Vitis vinifera subsp. sylvestris; and an herbaceous strata — many hygroskiophile and nemoral species, among those numerous pteridophytes(e.g. Asplenium onopteris, Athyrium filix-femina, Blechnum spicant, Dryopteris sp. pl., Osmunda regalis, Polystichum setiferum).
In many cases, such as the ones existing on the project’s intervention locations, several crop fields were settled near the water courses, along with some villages, in soils with a high value for agriculture, and thus the alder forests were reduced by the human activity to a thin row with a single line of trees. Agriculture appropriation of part of the alder habitats was accompanied by the fixation of thalwegs on the riverbanks and by the reduction in area of the summer temporary ponds and its associated sediment settling. In other words, in pristine conditions, certainly occurring before medieval times, alder forests were thicker and sinuous, mosaic-shaped with temporary ponds and sediment settling, and subject to more severe disturbances (such as floods). On the other hand, watercourses frequently changed their waterbeds. This statement is by itself a justification for investing on the expansion of its area.
Specifically, the project aims to favour biodiversity and the ecological integrity of the areas subject to intervention, through:
• The improvement of the conservation level of the riparian alder forests priority habitat [91E0 *Alluvial forests with Alnus glutinosa and Fraxinus excelsior (Alno-Padion, Alnion incanae, Salicion albae)];
• The opening of some clearings, creating a mosaic within the riparian alder forests priority habitat [91E0 *Alluvial forests with Alnus glutinosa and Fraxinus excelsior (Alno-Padion, Alnion incanae, Salicion albae)], alternating between dense and shady places and others with more sunlight, in order to allow the plantation and the settlement of macrophytes;
• The reconnection of old existing waterbeds, so that they may easily become periodically flooded, thus creating, more or less permanent, small ponds, which will then constitute vital areas for the settling and breeding of the odonata, allowing them to successfully complete their biological cycle;
• The potentiating of a larger heterogeneity of hydraulic forms and conditions, by thoroughly applying small blockages and deflectors, which will provide different current velocities and types of movement, thus allowing for changes in the micro-topography and therefore providing the creation of micro-habitats for the odonata and naiad and the improvement of the interactions between these and their hosts;
• The development of a program for the ex-situ reproduction of two naiad species [M. margaritifera and U. tumidiformis (=U. crassus)] and their respective hosts [the trout – Salmo trutta (sedentary form) and the endemic Squalius torgalensis (‘escalo do Mira’)]. This program intends to support the techniques for the reinforcement of both these populations with foreseeable results. To carry out this program, two aquiculture posts, owned by AFN (the National Forest Authority) will be used: one in Torno (Amarante), for the Margaritifera margaritifera; and the other at Campelo (Figueiró dos Vinhos), for the Unio tumidiformis;
• The establishment of several partnerships with local governments and local fishing and hunting clubs, in order to create two concession fishing zones, so as to assure protection areas for the naiads and long-term measures for the maintenance of the fish populations host to the naiad larvae. The project intends to demonstrate that, with local support and the active collaboration of the co-financing partners, it is possible to create an economic added-value through sports fishing management, thus allowing for the allocation of part of the profits for the maintenance of habitats and species.
ACTIONS AND MEANS INVOLVED
The project includes a preparatory phase, during which several tasks will be carried out:
• the characterization and diagnosis of the situation of the target habitats, not only through detailed cartography using topographic means, but also resorting to the River Habitat Survey technology, a tool to be used in the hydromorphological component monitoring, comprising the longitudinal and transversal scales of the watercourse, including the canal, the riparian zone and the waterbed;
• the inventory of the odonata and naiad populations, enriching the knowledge regarding its distribution on the selected areas, to be undertaken throughout the project’s duration;
• the inventory of the densities of the fish host to the naiad larvae, in order to assess the necessary repopulation effort without jeopardizing the survival of the wild populations;
• the definition of an action plan, including its operationalizing, scheduling and monitoring of indicators, verification means and accomplishment assumptions;
• the elaboration of technical projects for the interventions to be carried out on the field.
On a second phase, target habitat restoration will begin, including the reconfiguration of the waterbed and margins micro-topography, and naiad and their host fish will be captured. The ex-situ reproduction component will also begin at this stage, after the adjustment of the facilities and the installation of all necessary equipment.
On the third phase, habitat restoration actions will proceed, focusing mainly on the diversification of the microhabitat for the odonata, the naiad and the fish. The first colonies of naiad will be installed and the first juvenile host fish will be released. These actions will be subjected to permanent monitoring, in order to evaluate whether the different techniques used are suitable for the maintenance of habitats at a good conservation status and for the increase of invertebrate populations, and if these can be replicated on watercourses with similar characteristics, thus providing guidelines to ensure its continuity on the long-term.
This project will include a communication and result dissemination program. Apart from the compulsory measures, we predict the use of different means, according to the target audience and its dissemination range, in particular various printed materials, an exhibition, several audiovisual resources and a supplement for divulging the progress of the project’s results.
EXPECTED RESULTS (outputs and quantified achievements)
The project aims to undertake the following interventions, along a 12 km linear path on the River Paiva riparian zone and another one of 5 km on the Torgal stream:
– the restoration of around 15 ha of the priority habitat — 91E0 *Alluvial forests with Alnus glutinosa and Fraxinus excelsior (Alno-Padion, Alnion incanae, Salicion albae), corresponding to 11 ha on the SCI “Rio Paiva” and 4 ha on the SCI “Costa Sudoeste”;
– the increase in the habitat’s occupation area in about 5 ha.
To accomplish this, on these 20 ha, we foresee the undertaking of the following actions:
– to plant around 10.000 trees and shrubs, present on the local alder forests floristic composition (e.g. Alnus glutinosa, Fraxinus angustifolia, Laurus nobilis, Salix atrocinerea, Crataegus monogyna, Salix salviifolia subsp. salviifolia, Frangula alnus and Sambucus nigra);
– to reconnect 5 ha of old waterbeds and to improve 2 ha of new areas, in order to increase the odonata populations, through the settlement of macrophytes;
– to reinforce the population nucleus of M. Margaritifera, by adding 4500 juvenile individuals to the estimated 500 adults thought to exist on the area;
– to reinforce the population nucleus of U. tumidiformis (=U. crassus), by adding 400 juvenile individuals to the estimated 100 adults thought to exist on the area;
– to undertake two actions of fish host to larvae repopulation;
– to create and enliven two areas for concession sports fishing;
– to produce dissemination materials, such as a leaflet, a brochure, three videos and a documentary, two scientific illustrated posters portraying the odonata, the naiad and their hosts life cycle, as well as an interpretative exhibition about the riparian alder forests, complemented with a pedagogical exploration guide and a supplement on a newspaper.