The Mediterranean-climate ecosystems of the Mediterranean Basin (Image credit: Lisa Pompelli)


The Mediterranean basin is a region of exceptional richness of cultural and landscape variety and diversity. This is also a region of constant change. It is shaped by human activities, including land use changes, industry and population growth, combined with the growth of coastal urban regions. Also, the region is pressed by the development of tourism in highly attractive Mediterranean coastal areas, and rapidly evolving changes in consumption patterns, as a result of increasing development . The Mediterranean Sea is also one of the world’s busiest shipping routes. Moreover, it is a region of contrasts, as it includes countries with very different levels of income and social development. The region faces unequal distribution of resources, conflicts and large-scale migration.

Moreover, the Mediterranean region is exposed to several natural risks, like earthquakes, volcano eruptions, floods, fires or droughts. In this complex situation, the Mediterranean faces new challenges, due to global climate change. Based on global climate scenarios, the Mediterranean Sea has been classified as one of the most responsive regions to climate change. In fact, the rates of climate change observed in the Mediterranean Basin exceed the global trends for most variables.

Ocean-atmosphere interactions, climate oscillations and associated meteorological events (including extreme weather events) can be stochastic, non-linear, often irreversible from a thermodynamical approach. From simple biochemical and structural threshold-like responses, cascading effects propagate and amplify throughout the climate system. Moreover, in modeling climate dynamics there are two main sources for uncertainties have so far been identified: i) incomplete knowledge of physical mechanisms and processes to be included into models and socioeconomic impact models; ii) unknown human evolution and activity in the near future.
Moreover, in an era of rapid climate change, environmental variation is becoming more frequent and unpredictable as a consequence of climate change, and there is a pressing need to understand how organisms will cope with faster and less predictable variation in environmental conditions.

Consequences of climate change imply numerous risks for ecosystems and for human well-being such as: landscape and ecosystem degradation due to industrialization, urbanization and transport (pollution of air, water, soil and living resources) and unsustainable of use mineral and living resources of the land and the sea. Challenges resulting from these changes concern various domains, like fishing industry, agriculture, forest management and commercial and leisure activities.

As quick response to environment changes evolutionarists know the action of plasticity, that is, the capacity of an individual to adjust its phenology to environmental variables a sorto of Swerwing response. Phenotypic plasticity is a non-genetic character but it means that the organism’s phenotype is flexible and can be influenced by the environment.
Phenotypic plasticity is a key mechanism with which organisms can cope with a changing climate, as it allows individuals to respond to change within their lifetime. This is thought to be particularly important for species with long generation times, as evolutionary responses via natural selection may not produce change fast enough to mitigate the effects of a warmer climate.

An example of strategy as response to extreme events is the case of mediterranean marine pine (some of its variety). In particular I will focus about its strategy of surval against fire: Serotiny, which is a morphological feature whereby the cones remain closed for years after seed maturation and open after exposition to high temperatures. Sertony has been documented as, although not exclusively, a fire adaptation and it has been proved to be a more complex trait increasing the survival of released seeds which showed high biological quality (sound seeds, weight and germination rate) and higher heat insulation and resistance to fire.
This feature can be taken as an example of mitigation and adaptation measures which would be beneficial to humanity and its natural einvoronment against dangerous climate changes: a sustainable economy as plastic response to drawbacks of industrial and economic activity on climate. In evolutionary terms, genetical changes can be too slow for plants to adapt to the anthropogenic climate change, whereas strategies based on phenotipical plasticiy can result to be more benefitial to climate fast transtitions and tipping climate points.

From an economic point of view, national economies would be adversely affected not only by the direct impacts of climate change, but also through the cost of adaptive measures and the knock-on implications of changes elsewhere. Quantitative estimates of financial costsare unreliable but in general, developing countries are expected to suffer larger relative economic damages thandeveloped countries.

Table of contents:
A Basin of life under stress
1,2,….trees: maritime forests
Plasticity for survival: serotiny
Economic recoil

References & video talks
individuation of pines websites

– A Basin of life under stress

The Mediterranean-Climate Ecosystems is characterized by great weather, abundant harvests, and some of the world’s most cosmopolitan cities. Moreover, Mediterranean-climate ecosystems are home to a phenomenal number of unique plant species and interactions between the oceans and the atmosphere produce the dry summers and mild winters. The world’s Mediterranean-climate regions swing between years of drought and heightened fire risk, and years of catastrophic flooding. This is business as usual for native plants, many of which are built to survive dry times or rely on fires to regenerate natural communities.
The Mediterranean Basin covers a complex landscape with great topographic and climatic heterogeneity. The total area of the region is about 2.3 x 103 square kilometers. The region includes more than 20 nations arrayed on both sides of the Mediterranean Sea. While coastal areas are extensive due to the presence of numerous archipelagos and islands, much of this area consists of mountainous terrain with many areas above 2000 m elevation and peaks as high as 4500 m.
The climatic characteristics of the Mediterranean Basin together with other bioindicators (vegetation types) are used to define its borders. Climates of the Mediterranean Basin are notable for their high interannual variation in both rainfall and temperature extremes.

Human activities are the source of a great deal of waste, pollutants and disturbance. Pollution originating from atmospheric emissions, discharges into the sea and the recreational sector, is a factor to varying degrees. Maritime traffic transiting through this sea (30% of global flows) is an additional source of pollution, both chronic and accidental, while aquaculture sometimes leads to local concentrations of organic matter. Pollutants initially affect the coastal environment, then offshore areas and accumulate in secondary reservoirs. These pollutants contaminate water and living organisms. They affect the balance of marine ecosystems and threaten certain activities and uses

The impacts of the rise in temperatures, the decrease in rainfall, the multiplication of the number and intensity of extreme events and the possible rise in sea level overlap and amplify the already existing pressures of anthropogenic origin on the natural environment.
The growth of human activities and the effects of climate change have also altered the composition and distribution of certain species in the Basin. These changes represent risks for marine ecosystems and humans such as the loss of biodiversity, the impact on services provided and human toxicity.

Climate is changing rapidly and in various and complex ways since anthropogenic climate change is much more than global warming. It is not only mean air temperatures that are rising but also the frequency of extreme climatic events. Unusual heat waves and frosts are becoming more frequent together with severe droughts in arid and Mediterranean regions and floodings. The intensity of the radiation reaching the ecosystems is also changing.

Variations in gas concentrations within the Earth’s atmosphere cause changes in the climate, and these atmospheric gases are impacted by human activities as well as by natural disturbances including volcanic eruptions. Of the atmospheric gases, the main contributor to rates of climate change is the amount of carbon dioxide. Other gases such as nitrogen oxides and methane play a more variable role, depending on region and ecosystem type. Increased accumulations of atmospheric gases, particularly carbon dioxide, have resulted in positive radiative forcing (i.e., more incoming solar radiation than outgoing radiation).
For many mediterranean countries, anomalous changes in climate have become evident through insect epidemics, drought episodes and intense forest fires in the Mediterranean countries.
Climate changes are expected to impact vegetation manifesting as changes in vegetation extents, tree species compositions, growth rates, and mortality rates and also as species migrations.

Climate change is bringing a whole suite of abiotic stresses such as extreme temperatures, excessive irradiance and increased aridity, which are classic targets of ecophysiological studies. We now know that changing extreme temperature events are more relevant for plant survival than changing mean temperatures, with low-temperature extremes being particularly important. The climate is getting warmer but the chances for late or early season frosts are also increasing.
The dangerous periods for plants are not the coldest or the hottest moments of the year, but the transitions, when the extreme event hits plants that are either dehardened or not fully hardened.
These transitional periods are getting less predictable and more variable.

sources IntAct

One of the current challenges for research is to develop models based on predictions for climate change and economic scenarios that make it possible to assess impacts on a regional scale. One of the ways of addressing these issues is to undertake a coordinated cross-comparative exercise of impact-models at different spatial and temporal scales for different types of models, involving northern and southern shores. Another challenge consists of describing the past state of the sea in order to understand its variability and reconstitute its evolution. This challenge can be met by re-analyzing old data with current models. To better understand how the Mediterranean marine environment functions physically, numerous scientific challenges must be met both in its different constituent parts and in their interactions on different spatial and temporal scales. In fact, the Mediterranean Basin functions physically is influenced by highly contrasting physiography in terms of coastal continental land masses, the shoreline, continental shelves and deep basins and their connections. In addition, this sea is submitted to a complex and still largely unpredictable hydro-meteorological process.

– 1,2,….trees: maritime forests

Forests play a significant role in the Earth’s climate system by contributing to the cycle of atmospheric gases. Changes in the extent and characteristics of forests can greatly alter these gases. In particular, forests have a large impact on atmospheric carbon dioxide, since trees store carbon throughout their lives and then release it after death through decomposition.

As well as impacts on carbon and other atmospheric gases, forests affect water balance and soil stability, and biodiversity. In areas currently subject to flood events, changes in climate are expected to alter the frequency and magnitude of these events. Trees can reduce floods through water uptake; tree root systems can prevent soil losses and can reduce instability of steep slopes under increased precipitation. As well as affecting plant species, climate changes will impact animal species. Trees can help ameliorate these impacts by moderating local climates.
Forests under low water and high temperature stress will have decreased growth rates under hotter, dry climates may be more susceptible to attack by pathogens and insects, and in some cases (e.g., young Pinus pinaster stands), the impacts may be multiplicative rather than additive. Further, fire incidence may increase, particularly in areas where annual precipitation is expected to further decrease, such as the Mediterranean forests. However, these general trends will continue to be locally modulated by altitude and other biophysical features.

In order to evaluate the impacts of climate change on forests and the potential effects of management strategies to mitigate such changes, monitoring, modeling, and specific research programs are needed. Because of the long-term environmental and social implications of forest resource management, forest research has always had to transcend boundaries. Forest scientists have joined with other disciplines, typically the biological, mathematical and social sciences, to ensure that new and specialized research results are applied to forest landscape problems. This “integrating” principle necessitates bridging gaps between related disciplines and incorporating their specific knowledge to provide a suitable mix of desired services.

Forest management is particularly important under the current climate change since it can exacerbate the impact of human activities on forest dynamics and natural regeneration. The capacity of forests to cope with climate change has been considered to be relatively ample, and many physiological, genetic and evolutionary aspects have been suggested to contribute to the persistence of key forest trees and plants in a changing climate. However, the fast rate of current environmental change is imposing severe limitations to the capacity of trees to adapt to new climatic conditions.
A look into human history reveals that human induced deforestation and environmental degradation coupled with climate change has led to the collapse of civilizations as developed and rich as Maya and Anazasi.

In the Mediterranean area, the role of forest as carbon sinks is particularly significant since usually ecosystem services provided by forests are ­frequently of greater value than their direct productions.
Carbon sequestration changes over time, and with different management regimes in Mediterranean pine forests. The rotation length, thinning intensity, stand composition, as well as age structure influenced carbon stocks and carbon sequestration rates, with different results amongst species.

From an evolutionary point of view, trees have at least one intriguing feature: they tend to have high levels of genetic diversity, but at the same time, they are known for their low evolutionary rates. Thus, trees are characterized by a counterintuitive combination of rapid micro-evolutionary change and a low macro-evolutionary change. Trees experience highly heterogeneous environmental conditions and are exposed to extreme climatic events within their lifetime, which could contribute to the maintenance of their typically high genetic diversity. Trees are not only highly diverse but also highly fecund over their extended lifetime, allowing them to respond to high selection intensity and to adapt quickly to local conditions.
The intrinsically slow evolutionary rates of trees and the limits to their phenotypic plasticity imposed by complex environmental changes suggest a reduced capacity of forests to successfully cope with a rapid climate change coupled with many other simultaneous changes in the environment. However, there is not a clear picture of the real drivers of climate and atmospheric changes and of all relevant climatic aspects that are changing beyond the global rise of temperatures. Since many factors are simultaneously changing and they act in concert, and many species, which differ in their sensitivity and responsiveness to environmental change, co-occur and interact with each other leading to a complex network of responses.

– Plasticity for survival: serotiny

Wildfire frequency and intensity in the Mediterranean region are predicted to increase with climate and anthropogenic changes in the following decades. Pines species often posses fire-embracing and fire-avoiding strategies that increase the probability of persistence and performance in fire-prone habitats. One such strategy is serotiny which is the delayed seed release for more than a year by retaining the seeds in a woody structure. This implies an accumulation of a canopy seed bank. Serotiny confer fitness benefits in environments with frequent crown-fires, as the heat opens the cones and seeds are dispersed in the post-fire bed which is rich in resource and the competition and predation are low. It is typical of many proteaceae and some conifers, like some pine species. Although serotiny is primarily caused by fire, there are other seed release triggers that may work in tandem including periodic excess moisture, conditions of increased solar heat, atmospheric drying and parent plant death.

By delaying dispersal until a fire occurs, serotinous species recruit in postfi re conditions with high resource availability, low competition, and low predation (predator saturation), and thus, serotiny confers fi tness advantages in ecosystems under crown-fire regimes. Serotiny is variable not only among closely related species, but also within and among populations of a single species. There is evidence that serotiny increases with the frequency of crown fires and even a single fire may increase the population serotiny level given enough variability of the trait in the population.

Two recent papers analyse the serotiny of two mediterranean pines Pinus halepensis and Pinus pinaster. P. halepensis show higher proportion of serotinous cones than P. pinaster, but the latter retain the cones for longer. The two species show high variability of serotiny within and between populations, but they show a clear pattern of higher serotiny in populations subject to high frequency of crown-fires than those living in areas where crown-fires are rare or absent.

Example of trait divergence among populations living under different fire regime. Serotiny (as % of closed cones) in populations living under frequent crown fires (red boxes) and in populations where crown-fires are rare (green boxes) for two pine species, Pinus halepensis (Allepo pine, left) and P. pinaster (maritime pine, right).

Pines provide compelling evidence that fire can exert an evolutionary pressure on plants and thus shape our biodiversity. In addition, evolutionary fire ecology is providing insights to improve the management of our pine forests under changing conditions. The lessons learned from pines may guide research on the evolutionary ecology in other disciplines.

Phenotypic plasticity, the capacity of a single genotype to produce a range of phenotypes under different environmental conditions, is commonly perceived as being advantageous because it facilitates the persistence of species in spatially and temporally-heterogeneous environments. However, it can be adaptive, non-adaptive or neutral depending on its relation to the optimal fitness in the new environment. If the plastic response evolves in the same direction as that favoured by directional selection, then it is considered adaptive. In contrast, if the plastic response correlates negatively with the average fitness across environments, then it is considered to be non-adaptive (or maladaptive). Rather than being just a strategy for survival, plasticity becomes a necessary component to create phenotypes.

Whether or not plasticity favours adaptive evolution in new environments, is debatable. Historically, plasticity has been viewed as an impediment for adaptive responses because it can prevent the selection of the optimum genotype. However, recently this view has been revised because of the time it can buy for adaptive responses to occur in species and because of the potentially important role that non-adaptive plasticity plays in enhancing selective responses to environmental perturbations.
There is renewed interest in understanding the relationship between plasticity, selection and adaptation because of their important role in determining a species capacity for trans-generational acclimatisation and rapid adaptation during periods of fast environmental change, such as those occurring and predicted to occur as a consequence of anthropogenic activities during the 21st century.
Organisms have responded to recent and ongoing climate change through both phenotypic plasticity and evolution. However, the interaction between plasticity and evolution in determining adaptive responses of populations to climate change is unclear. Few studies have documented evolutionary changes in plasticity itself in response to climate change, but such changes seem likely given that climate change may increase environmental variability and generate novel climatic conditions.
Moreover, organisms might cope in different ways with quickly changing, less predictable climate variations. Organisms tend to adopt different strategies for dealing with changes in their environment: some of them adjust their gene expression either at birth or throughout their lifetime. Some other species produce offspring that are adapted to one of two possible outcomes so that at least half of their offspring survive, and some rely on plain old evolution to keep up with environmental changes.

Again back to mediterranean pines, Serotiny is a key adaptive trait of plants in fire-prone environments, ant is the expression of phenotypic plasticity (the ability of a genotype to generate different phenotypes ​​for a given trait under different environmental conditions). It is an important strategy for plants to maximize their fitness in fluctuating environments, but many phenotypic characters vary depending on growth and development. Therefore, conclusions about plasticity may change if developmental differences are taken into account, for example by studying the covariation of a given character with the size of the individual (allometry).
There is a difference between population differentiation (genetic effect) from phenotypic plasticity (environmental effect) of serotiny in the species Aleppo pine under different environments. Anyway increased aridity due to climate change might decrease the aerial seed bank as a plastic response, not necessarily adaptive, so the plastic response in certain cirumstnces is potentially maladaptive under a scenario of frequent wildfires.
For example, Pinus halepensis exhibits a dual life history strategy. It is remarkably efficient in exploiting new establishment opportunities generated both by fire and by other disturbances. This dual strategy, combined with thefact that its ability to regenerate after fire is one ofthe main characteristics of its invasive nature, makesthe evaluation of any single trait difficult. This indicates that fire may serve as a direct select-ive agent that shapes plant traits in the Mediterraneanbasin, and in Pine halepensis in particular (and also the maritime pine). Moreover, in P.halepensis, bark thickness is another a key structural feature in the protection against fire.
Populations from areas with higher fire frequency had thicker basal bark, while those from areas with severe droughts and short vegetative periods, had thinner bark. In conclusion, drought-stressed trees have a higher risk to die from fires before achieving reproduction and building a sufficient aerial seed bank. Determining the possible phenotypic plasticity of bark thickness separately from genetic differences within species is fundamental to improve our understanding of the trade-offs related to bark that can limit adaptive evolution under a changing climate. P. halepensis can achieve a sufficient bark thickness to survive surface and moderately-intense fires. This suggests a more variable adaptive strategy to cope with fire than has been considered so far for this species so providing experimental evidence of plasticity for this key adaptive trait in interaction with population differentiation.
In conclusion, Serotiny is one of the adaptations that has made halepensis pine so successful at regenerating after wildfire is the ability to produce serotinous cones. But in an uncertain enviroinment due to climate change, serotiny alone could not be an andvantage for all situations. Considering also bark thikness is an example of a holistic approach of adaptation in nature as also in societies.

As an example of example, as humans release greenhouse gasses into the atmosphere, we increase carbon dioxide levels worldwide. In this high-carbon-dioxide environment, plants with genes that cause them to produce fewer stomata will have an advantage over other plants since they will be better able to conserve water, while still getting enough carbon dioxide. Those few-stomata plants will survive better, reproduce more, and pass their genes for few stomata on to their offspring. Through this process of evolution by natural selection, plant populations with fewer stomata will evolve over many generations.
Whether or not plasticity favours adaptive evolution in new environments, is debatable. Historically, plasticity has been viewed as an impediment for adaptive responses because it can prevent the selection of the optimum genotype. However, recently this view has been revised because of the time it can buy for adaptive responses to occur in species and because of the potentially important role that non-adaptive plasticity plays in enhancing selective responses to environmental perturbations.
There is renewed interest in understanding the relationship between plasticity, selection and adaptation because of their important role in determining a species capacity for trans-generational acclimatisation and rapid adaptation during periods of fast environmental change, such as those occurring and predicted to occur as a consequence of anthropogenic activities during the 21st century.
It has proven difficult to conclusively distinguish whether phenotypic changes are genetically based or the result of phenotypic plasticity. So the difference between phenotypic plasticity or evolutionary genetic changecan be made only in terms of temporal and spatial scale.

– Economic recoil

The Mediterranean is one of the world’s most remarkable regional seas, with a high level of activity in several sectors: fishing, mining, industry, town expansion, trade and tourism.
The study of economic and social consequences of climate change is mostly focused on the issue of water resources and assessment of a range of potential problems such as increasing droughts, adequate irrigation, reduced water quality and population migration due to severe shortages. In general researchers examine issues surrounding land use including desertification, degradation, agriculture and waste management.

The impacts of climate change on the Mediterranean environment will relate particularly to Water, via a change of its cycle due to a rise in evaporation and a decrease in rainfall. This water problem will be of crucial importance with regard to the issue of sustainable development in the region; Soil, via the acceleration of already existing desertification phenomena; Land and marine biological diversity (animal and plant), via a displacement northwards and in altitude of certain species, extinction of less mobile or more climate sensitive species, and emergence of new species; Forests, via a rise in fire hazards and parasite risks.

The impacts are particularly on economic sectors as: agriculture and fishery (reduction of yields), tourism attractiveness (heat waves, water scarcity), coastal areas and infrastructures (significant exposure to the action of waves, coastal storms and other extreme weather events, rise in sea level), human health (heat waves), the energy sector (water needs for power plants, hydropower and increased consumption).
So, mediterranean countries would experience severe losses in agricultural production, due to increased temperature and reduced water availability.

The effects have been mostly negative, such as in the Mediterranean where more heat extremes and less rain are expected. This situation could increase competition for water, while producing energy will become more difficult. (infograpics from EU)

In this context, taking into account the environment in economic and political decisions must be a priority for the future of the Mediterranean. Policy responses to climate change should be based on scientific evidence. Consideration of scientific evidence includes clear communication of uncertainties as part of normal practice. While the uncertainty indications could make the scientific assessment more difficult to include in policy-making, uncertainties should not be used as an excuse for inaction. On the contrary, the assessment should help people to better understand the complexity of links among climate, environmental and societal parameters.  

In this perpsective, climate change offers both challenges and opportunities for macro-economists in order to build a transition to a zero carbon economy, in order to mantain minimal the cost to economic growth and consumer standards. But achieving that objective will require a major redirection of investment from fossil fuels to renewable energy sources, and will not occur without forceful public policies, including the introduction of carbon taxes, regulation and technology development support.

The most fundamental problem is that human activities are already seriously degrading the environment as a life support system,through their key role in desertification, over-extraction of water from aquifers and pollution. Problems are furtherexacerbated in the south where population growth presents the ever-more challenging prospect of improving quality oflife while also accommodating more people. In view of these factors, ensuring sustainable development in the Mediterranean region will require action both to adaptto the impacts of climate change and to minimise emissions of greenhouse gases.


– References

MedECC report CLIMATE AND ENVIRONMENTAL CHANGE IN THE MEDITERRANEAN – MAIN FACTS  and pdf here
– Managing Forest Ecosystems: The Challenge of Climate Change
Evolution of serotiny in maritime pine (Pinus pinaster) in the light of increasing frequency of fires- Managing Forest Ecosystems: The Challenge of Climate Change
FEMIP detailed study on Climate Change and Energy in the Mediterranean
j.g. pausas’ blog
– Greenpeace report CLIMATE CHANGE AND THE MEDITERRANEAN REGION
Fire structures pine Serotiny at different scales
CAUSE DI INSTABILITÀ NELLE PINETE COSTIERE DI PINO D’ALEPPO
Serotiny
– MicroMega blog Plasticità: un nuovo fattore nell’evoluzione?
– blog Understanding the role of plasticity in evolution
– International Cooperative for the Management of Mediterranean-Climate Ecosystems (INCOMME)
– Mediterranean-Climate Ecosystems by UCNRS
– Climate change is driving wildfires, and not just in California
Adapting to global change in the Mediterranean Sea
– book The Physical Geography of the Mediterranean (in particular chapter 3)
– book Ocean Processes in Climate Dynamics: Global and Mediterranean Examples
– wiley special issue: Climate change, adaptation, and phenotypic plasticity
– paper Nature SciRep: The evolution of phenotypic plasticity under global change
– paper proceeding Royal Society: Evolution of plasticity and adaptive responses to climate change along climate gradients
– paper PNAS: Evolutionary tipping points in the capacity to adapt to environmental change
– Nature or nurture: Evolution and phenotypic plasticity
– EU GROWINPRO project about Climate change: challenges and opportunities
– Studying Tree Responses to Extreme Events Editorial and Research book



– Detection of Pine trees

PINO D”ALEPPO:
E’ un pino litoraneo che si può rinvenire nelle pinete delle terre circummediterranee, un albero elegante, dal portamento estroso, più variamente e riccamente ramificato degli altri pini litoranei (Pino domestico, Pino marittimo, ecc). La chioma è più rada e di colore più pallido, tondeggiante in alto ma talvolta variamente suddivisa sui rami e sui tronchi contorti. Vive di preferenza nella fascia più calda e asciutta dei nostri litorali. Le pinete a Pino d’Aleppo sono molto aperte e luminose, e ciò spiega l’esuberante sviluppo della macchia mediterranea al loro interno.



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