Mediterranean Context

What is a Mediterranean-type ecosystem?

Mediterranean-type ecosystems are found in five regions of the globe: California, central Chile, Mediterranean Basin, southern Cape region and south western and southern Australia, between 40º and 32º latitude, and where land is influenced by cold offshore ocean currents. The flora of the Mediterranean areas is one of the richest in the world, and annual grasslands, shrublands, dry woodlands and forests are typical. The climate is highly seasonal and characterized by warm, dry summers, i.e., by a seasonal drought, and cool, rainy winters. Spring and autumn are usually the growing seasons (González-Fernández et al., 2013).

The Mediterranean region in numbers (in 2010):
6.5% of land mass
7.7% of the global population
13.5% of global GDP (16.2% in 1990)
32% of international tourism
60% of people living in water-poor countries globally
7.7% of CO₂ emissions

Climate change in the Mediterranean - Hotter and drier

The Mediterranean basin has many morphologic, geographical and societal characteristics, which make its climate scientifically interesting. The Mediterranean region will be strongly affected by climate change. Data published confirm once more that climate change is already a reality in the region. Models forecast a substantial increase in water shortage, due in larger part to the increase of temperatures than to the decrease in rainfall; therefore, the risk of drought in summer will increase around southern Europe (IPCC, 2001). During the twentieth century, temperatures have increased on average by more than 1°C in the south-western Europe (Iberian Peninsula and southern France) and the trend is clearly accelerating since the 1970s. In some parts of southern and eastern Mediterranean region, there was also a decline in rainfall of up to 20%. Temperatures are expected to continue to increase in the coming decades, with considerable effects on human society and the environment. The vulnerability of Mediterranean countries to climate change is also related to the constant degradation of water resources (e.g.> overexploitation, pollution, salinization, reduced rainfall) and to the increase of water demand by agricultural, urban and energy sectors.

In Nice, between 1973 and 2012, the mean temperature increased of 0.42 °C per decade, i.e. that mean temperatures could increase of 3.54°C from 2013 till 2100. From 1990 the precipitation amounts decreased of - 5.33mm per year and the mean temperature increased of 0.06°C per year. Since 2003, six of the warmest years were recorded (Sicard et al., 2014, under review).

Mediterranean forest research: challenges and opportunities in a changing environment

Mediterranean forests have historically been subjected to numerous threats (forest fires, over-exploitation, deforestation, degradation), today accentuated under climate and land use changes.

Forests and woodlands of the Mediterranean region cover about 80 Mha, about 9% of the region’s land area; they constitute a unique world natural heritage in terms of biological diversity, hosting around 25,000 species of vascular plants, (50% are endemic species) and a high degree of tree richness and endemism (290 indigenous tree species with 201 endemics) with extraordinary genetic diversity. Mediterranean forests provide a wide array of environmental services and products. Despite their important role as primary green infrastructure of the region, Mediterranean forests are subject to numerous threats such as forest fires, over-exploitation, deforestation and degradation. These threats, historically present, are nowadays accentuated in a context of climate and land use changes. Among all bioclimatic regions, the Mediterranean area appears to be the most vulnerable to global change. In this respect, the Mediterranean area is especially sensitive to any climate change because it represents a transition zone between arid and humid regions of the world (Scarascia-Mugnozza and Matteucci, 2012).

Expected climate change will result in the expansion of Mediterranean conditions to new areas. Moreover, increased areas of unmanaged forest in the north and deforestation and overexploitation in the south will increase the level of biotic (pests and diseases) and abiotic (fires, droughts, etc.) risks reducing the possibilities for adaptation to climate change.

Forest health and vitality in Southeastern France

The Mediterranean coast in southern France and northern Spain was a hot spot with specifically high defoliation in several species groups. Plots showing deterioration, between 2002 and 2010, are scattered across Europe, but their share is particularly high in southern France, Czech Republic and northeastern Italy (Fischer and Lorenz, 2011).

In Southeastern France, defoliation slightly increased for most of the broadleaved species. Quercus pubescens and evergreen oak, species which are frequent, still had the worst crown condition of all monitored species in 2010, and did not show any sign of improvement. The number of discolored trees was still low except for Populus spp., Fagus sylvatica, Prunus avium and Pinus halepensis. Close to Nice, over the period 2000-2012, the crown condition of the Mediterranean lowland pines, composed of Pinus halepensis and Pinus cembra, is characterized by a considerable increase in mean defoliation of the pine trees since 2000. The defoliation is slightly higher for P. halepensis (34.4%), along the French Riviera, as compared to the P. cembra (27.1%) within the Mercantour National Park. The trends analysis showed deterioration, indeed in average, the needle loss increased of 0.67% per year for P. halepensis and of 0.90% per year for P. cembra between 2000 and 2012. Over the last twelve years, temporal defoliation trends showed a continuously increasing defoliation of pine trees.

Ozone pollution and trends in Mediterranean area

The European region at highest O₃ risk is the Mediterranean area. Ozone formation occurs at high temperature in presence of solar radiation, which is elevated in Mediterranean-type ecosystems. Around the Mediterranean basin, over the time period 2000-2010, at urban and suburban sites, the ozone mean concentrations ranged from 15ppb (North Italy) to 48ppb in South-eastern France, at Grasse, where NMVOC emissions increased till 2007 because of the installation of perfumery and industrial chemistry factories (Directive 96/61/CE). The highest concentrations (> 40 ppb) were found in South-eastern France.

Analyzing hourly ozone data from 214 European background sites over the time period 2000-2010, Sicard et al. (2013) demonstrated for the first time that the ozone control measures are effective at rural sites (-0.43 % per year), while ozone concentrations are still increasing in the cities (+0.64% per year). The Western European Mediterranean basin is expected to be more strongly affected by climate change, including ozone pollution, than most of the other regions of the world. At cities ozone average levels increased, but the peak ozone concentrations decreased. In all station types, a significant reduction in the amplitude of peak ozone concentrations was found at more than 75% of stations (hourly peak, - 1.14% per year). The peak reduction may largely be attributed to the reduction in NOx and VOC emissions within the European Union which started in the early 1990s.

Surface ozone concentrations in the South-western European Mediterranean Basin were relatively high relative to human well-being and vegetation impacts (Sicard et al., 2013).

Ozone pollution effects on Mediterranean ecosystem biodiversity

Ozone can potentially affect the biodiversity of Southern European ecosystems through both direct effects on natural vegetation, and indirectly, sensitizing plants to other environmental and biotic stresses, or altering biogeochemical cycling, processes subjected to future variations under global change scenarios. In summary, current knowledge on direct in Mediterranean European countries is still too limited to draw firm conclusions and quantifications. Importantly, field validation of O₃ effects observed under experimental conditions is still lacking for many species and plant communities. Also indirect effects remain mostly unknown, despite the fact that they are probably of great importance in terms of assessing O₃ effects on ecosystem biodiversity.

Nitrogen deposition effects on Mediterranean ecosystem biodiversity

Dry deposition is usually the main form of atmospheric input in Mediterranean systems and N frequently accumulates in soil and on plant surfaces during dry periods, becoming available as high N concentration pulses with rainfall events. These anthropogenic N inputs, together with the introduction of alien species from other equivalent Mediterranean regions, are currently amongst the main threats to Mediterranean ecosystems, as they usually lead to altered fire cycle and loss of native species as a consequence of competitive exclusion.


González-Fernández I, Gerosa G, Bermejo V, Marzuoli R, Calvete-Sogo H, Finco A, García-Gómez H, Alonso R., 2013, “Ozone effects on vegetation biodiversity in a biodiversity “hotspot” (southern Europe)”. In: Mills G, Wagg S, Harmens H (eds). Ozone Pollution: Impacts on ecosystem services and biodiversity. ICP Vegetation Programme Coordination Centre, UNECE-CLRTAP WGE, pp.38-42

Sicard P., De Marco A., Troussier F., Renou C., Vas N., Paoletti E., “Decrease in surface ozone concentrations at Mediterranean remote sites and increase in the cities”. Atmospheric Environment 79 (2013) 705-715.

Scarascia-Mugnozza G., Matteucci G., 2012, “Mediterranean forest research: challenges and opportunities in a changing environment”, Energia, ambiante e innovazione, 58-65

FAO Forestry Department, 2013, “State of Mediterranean forests in 2013”, ISBN 978-92-5-107984-3 (173p)

Fischer R., Lorenz M. (eds.). 2011: Forest Condition in Europe, 2011 Technical Report of ICP Forests and FutMon. Work Report of the Institute for World Forestry 2011/1. ICP Forests, Hamburg, 2011, 212 pp.