Portugal adapts forest management to global change scenarios in drylands
Half of Portugal’s countryside is dry. Extremely dry. Too dry for many species, only resistant ones can survive. The semiarid climate will expand in the whole region of Alentejo due to increasingly hot climate in future years. In times of change it is important to adapt to the rising amount of droughts and increasing heat as soon as possible to save the land and ecosystems. Native forests consist of holm oak and cork oak; pines were introduced afterwords – the more plants grow, the less susceptibility to desertification you can expect.
Furthermore, nearly untamable forest fires as well as mandatory shrub clearings destroy wildlife fauna and flora recurrently. Different reforestation projects have analysed the land for decades already – but with little success. AdaptForChange finally has found a solution to fight desertification and the impacts of climate change.
The expansion of Portugal’s dry land demands adaption – now
For years members of different reforestation projects already planted the two native oak species in the Alentejo region mixed with pines, but unfortunately on the long-term nobody observed the development of the ecosystems. Since 1938 until today, programs as e.g. the “Plano de Povoamento Florestal” took care of the forests to protect the soil and to improve ecosystem functioning. But until the trees overcame their childhood, each project had ended and nobody evaluated the tree-population after some years. Several trees died for conclusive reasons such as microclimate – that was the point when “AdaptForChange” examined the data of the last 30 years. The “AdaptForChange” project involves many partners, including the "Center for Ecology, Evolution and Environmental Changes”, which realizes many different projects in Portugal. This project had a duration of one year and officially ended in 2017, accompanied by the publication of several e-books, giving their knowledge to politicians and farmers who now understand the sensibility of what to plant where and why. The EAA Grants - Programa AdaPT Sectorial gave fundings to the project.
Alice Nunes became a Post Doc Researcher in the “Ecology of Environmental Change” (eChanges) research subgroup after finishing her PhD in Ecology and Functional Biodiversity at the University of Lisbon. Her teacher was Cristina Branquinho, who coordinated the project team of different research institutions, NGOs and company-partners. Together they were developing a model to point out which areas could be regenerated cost-effectively or which ones could get assisted reforestation-methods. With this study long-term survival can finally be guaranteed, always based on the objectives of all stakeholders such as the fulfillment of national (ENAAC) and international policies (Conventions on Biodiversity, Climate Change and Desertification) but also the accomplishment of the goals of land owners and local authorities.
FROM LOCAL TO GLOBAL SCALES: STUDYING ECOSYSTEMS DURING CLIMATE CHANGE
To realize the study the fifteen-person team selected a model semiarid area in Portugal which already has a climate change scenario – these conditions are expected in other regions of Portugal too. This means that the group could examine the outcome of an oak-forest for other areas in future years under climate change impacts. The involvement of stakeholders generated the technical capability to assure the continuity of the project.
Portugal is divided into five regions. Alentejo region is in Southern Portugal above Algarve. Mértola is the municipality in southeastern Alentejo near the Spanish border. The population is around 7,000 people in an area of approximately 1,290 square kilometers. It has the second-lowest population center by density with 5.62 persons per square kilometer.
In different workshops with the stakeholders the team collected all data of past studies and brought it down to a common denominator, better said in a geographic database by using remote sensing and field studies. Holm oak and cork oak are one of the main products grown in Portugal. They can survive well in dry areas, which are savannah-like. The students discovered indicators and conditions where the degradation of the plants could be avoided. They also evaluated the soil quality and saw that it is constantly decreasing with more aridity.
Pines give shadow to the oaks since they grow much faster and help them to survive in even drier climate since young oak trees are much more sensitive than pines. But at some point, pines turn into competitors with oaks, and oaks will stay much smaller if pines are growing next to them.
Still, under the conditions that we have now and in the future, it is best for farmers to plant a heterogene reforestation - considering the use of holm oak, cork oak, and pines according to macroclimate, and also to microclimatic conditions within the same land property. Climate will become hotter and dryer, so farmers have to consider this and also grow more holm oak because it is more resilient to dryness and aridity, as shown in the diagram. Pines are better at CO2-sequestration because they grow faster than oaks. For each microclimate it is calculable which type and number of plants would be the best combination.
SHRUBS AND FOREST FIRES
Not only climate change but also humankind has influence to the reforestation process. Periodic shrub clearing is mandatory by the government which has positive as well as negative aspects. On the one hand it prevents fires that burst easily the more shrub you have. So, it is important to clean vegetation regularly. But on the other hand, shrub has its own wildlife which loses its habitat and shelter. The solution is to not clear it all at once but to take some shrub away so that animals have the chance to move. Land abandoning augments this problem apparently.
In terms of forest fires oaks, especially cork oaks have the advantage of not burning easily since cork is a thermic isolator and resilient to fires because of its physical character. Cork oaks can serve as fire barriers for the whole forest. In general, drier regions like Mértola are not very prone to forest fires since there is not so much combustible as in other Portuguese regions.
RISING AWARENESS WAS THE FIRST STEP INTO THE RIGHT DIRECTION
Alice Nunes’ message and feedback on the project is clear: “Of course it would have been better to do the project for a longer time - one year was short, but still it was a great opportunity to have contact to around 20 stakeholders and different politicians, and to share ideas and knowledge. Co-workers were having all kind of backgrounds which made the workshops useful for everybody who participated. The total résumé was to keep on working and to implement the plans we sketched. Still, there are more evaluations and guidelines in progress for city-planners and farmers. Within the project, we also analyze complementary products such as bees, mushrooms, basil, lavender, and others, so that farmers can get additional income with other products too, so they are not only dependent on oaks.”