This paper focuses on past woodland changes and land uses in an ancient mining area of the Eastern Pyrenees (Ari ege, France). The area discussed is located at the western entrance of the Vicdessos, a valley with significant steel production, and it is crossed by the road used from the 14th c. to the end of the 18th c. for the iron-charcoal exchange with the forest Province of Couserans. The introduction of this singular exchange and the silver ore mining history of this border area raise the question of their impact on forest cover changes and changes in human practices and their link with anthropisation processes. To deal with this issue, we put in place an interdisciplinary approach involving archaeology, charcoal analysis, ecological history and geochemistry. The archaeological investigations and fourteen radiocarbon ages allowed characterising and dating of mining and charcoal-making remains. They situate the emergence of metal ore mining during the Second Iron Age and charcoal making activity between the 15th and 17th c. The geochemical analysis of 9 galena samples showed some different isotopic signatures between ores extracted in ancient times and those mined during the modern period. The charcoal analysis of (i) 2442 charcoals from 31 charcoal kilns (ii) 500 from one pedoarchaeological pit excavated in a waste heap related to firesetting, and (iii) 250 from two pedoanthracological sampling points carried out in the charcoal burning forest, permits a detailed reconstruction of the woodland cover changes from the Second Iron Age to the 19th c. Furthermore, the combination of data from different disciplines allows for a long-term reconstruction of human practices history and woodland management for different uses. In particular, the results show the transformation of the fir-beech forest, still dominated by fir around the turn of the Roman era, into pure beech wood managed on northern slopes for human daily needs, occasionally mining, lumber and mainly charcoal production until the 19th c. The elimination of fir dates back to the 17th c. This assumes the end of lumber activities in that period. Pedoanthracological and palynological data suggest that southern slopes, progressively deforested since the Bronze Age, were entirely devoted to permanent agropastoral activities probably at least since the end of the medieval period.

The term agroforestry covers practices that are promoted to maintain or even enhance biodiversity. However, the relationship between agroforestry and invasive species is rarely addressed, even though the spread of such species is an important issue, not only ecologically but also economically and socially. Over the past few decades, humans have greatly accelerated the process of biological invasions, to such an extent that they are now recognized as the second cause of rapid decline in biodiversity. In France (as in other parts in Europe) abandonment of agricultural land in remote areas is a major problem having socio-economic, landscape and environmental implications. The objective of the research presented here was to find a method for studying the relationship between traditional agroforestry systems and invasive species, despite a lack of available data. We investigated the evolution of a traditional agroforestry system in the Pyrenean foothills, where invasive species are abundant, by implementing two complementary methods: i/ interviews highlighting the local stakeholders' perception of landscape evolution, invasive species and the challenges they represent for the local traditional agroforestry landscapes, and ii/ detailed mapping of an area occupied by invasive plants, by means of very high resolution spatial technologies using UAV's and aerial photography. The results show that invasive species have spread in relation with the abandonment of agricultural land, which has also led to "landscape closure" by the encroachment of natural afforestation. They also underline the difficulty of assessing the spread of invasive species. This situation is of major importance in terms of land-use planning, as the various stakeholders have different perceptions of the problem, and it raises questions about the sustainability of practices and territories.

Of particular importance in shaping species assemblages is the spatial heterogeneity of the environment. The aim of our study was to investigate the influence of spatial heterogeneity and environmental complexity on the distribution of ant functional groups and species diversity along altitudinal gradients in a temperate ecosystem (Pyrenees Mountains). During three summers, we sampled 20 sites distributed across two Pyrenean valleys ranging in altitude from 1,009 to 2,339 rn by using pitfall traps and band collection. The environment around each sampling points was characterized by using both physical and land-cover variables. We then used a self-organizing map algorithm (SOM, neural network) to detect and

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