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Saturday, 25 May 2013

Assessing the Natura 2000 network with a common breeding bird survey


Beside the classical biodiversity protection measures, such as Natural Reserves or National Parks which are designated by European state members, the European Union has coordinated the Natura 2000 network. This network is the most important conservation effort so far in Europe regarding coverage (ca. 17% of the terrestrial surface of Europe). The legal basis, the Bird Directive (79/409/EEC, amended 2009: 2009/147/EC) and the Habitat Directive (92/43/EEC, consolidated 2007) aim at maintaining wild species and habitat in a favourable conservation status. The network covers 12.54% of territorial France (Figure 1). France chooses to define management plans for each site through contracts between the land owner and the state. Farmland contracts are agro-environment schemes, while owners of non-agricultural lands receive incentives and tax exemptions from the state to implement measures that favour biodiversity, as defined in individual contracts. To date only half of all the sites have management plans (Debain, 2011), and management only began to be implemented in 2005.




Figure 1. Natura 2000 areas in metropolitan France (Corsica Island excluded). Blue areas are the Special Areas for Conservation, designated following the Habitat directive, orange areas are the Special Protection Areas, designated following the Bird directive.



Common species importance in ecosystem functioning is well known. Their decline could have important ecological and evolutionary consequences. Yet, the N2000 network, as well as other protection measures, hardly acknowledges their importance. Even though the Bird Directivexplicitly emphasize that every wild bird species should be protected, the only legal obligation for member state is to designate areas containing species included in the Annex1 of this directive. As this annex mainly contains threatened or rare species, common biodiversity is almost neglected.


Using the French volunteer-based breeding bird survey, we assessed whether the N2000 network was favourable to common bird species. We evaluate whether the relative abundance of the 100 most common bird species was higher inside than outside the network. We also assessed the habitat specialization and the mean trophic index of the communities inside the network.


Fifty-four (54%) species exhibited an increase in abundance with an increasing N2000 coverage in the survey plot (P < 0.05) of which 11 were farmland specialists and nine were woodland specialists (representing 55 and 43% ff the farmland and woodland species occurring in France). Six species decreased in abundance, of which two were farmland species and one was a woodland species (10 and 5% of the farmland and woodland species). There was no significant effect of N2000 coverage for the remaining 40 species (Figure2).

Figure 2. Number of species more, less or equally abundant with an increase in N2000 coverage. Species as classified according to their habitat specialization.


The Community Specialization Index (a measure of the mean habitat specialization of the community: the higher the index, the more specialized is the community) and the Bird Trophic Index (a measure of the mean trophic level: the higher, the more the community comprises top-predators) are increasing with the N2000 coverage in survey plots (Figure 3).

Figure 3. Response of (a) the Community Specialization Index and of (b) the Bird Trophic Index to the Natura 2000 coverage. Natura 2000 ratio is the proportion of the plot covered by N2000. After Pellissier et al., 2013, modified.



Thus, the N2000 network appeared to have an interesting coverage of the population of wild bird species in France. Moreover, the communities were more habitat-specialized, indicating a potential for mitigating the threats faced by the specialized species throughout Europe. It also appeared that, given the higher abundance of top-predator species within the N2000 areas, these areas were likely to harbour highly functional bird communities, as the presence of top-predator is an indicator of the presence of several trophic level.


As the management of the N2000 areas barely started in France, these increases in community measures are likely to be caused by a designation effect. This means that the N2000 areas, even though designated based upon the presence of species listed in the annexes of the directives are favourable for a large range of common bird species.

Finally, the volunteer based biodiversity surveys (such as Vigie Nature: vigienature.mnhn.fr), because of their large geographical and temporal coverage, appeared to be efficient tools to assess large scale protection networks.


References 

Debain, S. (2011). Natura 2000, le plus grand réseau écologique mondial. Espaces Naturels 36, 8 [in French].

Pellissier, V., Touroult, J., Julliard, R., Siblet, J.P. & Jiguet, F. 2013. Assessing the Natura 2000network with a common breeding bird survey. Animal Conservation. DOI: 10.1111/acv.12030

Communicated by Vincent Pellissier - UMR 7204 MNHN-CNRS-UPMC, CERSP, Muséum National d'Histoire Naturelle, Paris, France and SPN, Muséum National d'Histoire Naturelle, Paris, France. E-mail: vincent.pellissier@gmail.com 


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