Why?
Ecosystems are suffering unprecedented degradation as a consequence of global change, compromising the provision of important services for human well-being.
Climate change
One of the main drivers of global change is climate change, which threatens major changes in the regime of temperature, precipitation, and the frequency and intensity of extreme events, putting ecosystems as we currently know them at risk.
Forests
They are large providers of services, and an essential factor in the greenhouse gas buildup, with great importance in mitigating the effects of climate change.
However, climate change is altering its composition, structure and functioning, compromising these capabilities.
Species mix
In recent years, the richness of tree species in forest stands has been identified as a promising management strategy for increasing the resilience, productivity and provision of services of these systems, compared to monospecific stands (a single species). The ADAPTAMIX Project was born seeking to expand knowledge in this field.
What do forest ecosystems offer us?
In addition to their value for biodiversity conservation, forests provide multiple essential services to humans.
Supporting services
Supply of wood products (for construction, energy production, and paper production) and non-wood products such as medicines, fibers, food, resins, or oils.
Regulating services
Water and nutrient cycle regulation, natural pest control, pollination, water purification, air purification, carbon storage, etc.
Cultural services
Aesthetic, spiritual and religious values; contribution to physical and mental health, as well as recreational and leisure services. Of course, forests are also a great source of cultural knowledge.
Let the figures speak
Source: Global Forest Resources Assessment (FAO, 2020).
What is happening (and can it get worse)?
General objective
Evaluate whether forest diversity improves the productivity and stability of Mediterranean forest ecosystems in response to drought events.
The working species are Pinus sylvestris and Quercus pyrenaica.
Specific objectives
1
We aim to analyze whether trees growing in mixed stands have higher tree growth and were more resilient and resistant to drought events than trees growing in monospecific stands. We will build tree-ring chronologies in pine and oak individuals growing in mixed and monospecific stands and analyze growth sensibility to among-years water availability, and growth stability (resilience and resistance) to drought events.
3
We aim to analyze whether admixture enhance nutrient availability at the stand level, and subsequently tree nutritional status. We will combine leaf nutrient analyses with measurements of soil nutrient availability, decomposition and respiration. This will allow us to compare tree nutritional status and soil nutrient availability in mixed and monospecific stands.
2
We aim to determine the impact of extreme drought events on water use efficiency, stomatal conductance and transpiration in pine and oak trees growing in mixed and monospecific stands. For this, we will conduct carbon and oxygen isotopic analysis in tree rings during and after the drought event. This will allow us to evaluate tree physiological response to drought, but also the recovery of pre-drought physiological performance levels after the drought event (i.e. physiological resilience).
4
We aim to determine whether plant-plant interactions (from positive to negative interactions) may shift under increased aridity. For this, we will conduct a field experiment planting pine and oak seedlings under two competition treatments (intra-specific and inter-specific competition), two temperature treatments (current and increased temperature) and two water availability treatments (current and reduced precipitation). We will experimentally manipulate temperature and precipitation by using open top chambers and rainfall exclusion units, respectively. The experimental setup will allow us to test the interaction between treatments. We will conduct performance (survival and growth), physiological (water stress, water use efficiency and stomatal conductance) and nutritional measurements.
