Maps with potential changes in the distribution of the main species

Maps with changes in the distribution of the main species in Romania

The IPCC has developed a set of short- and medium-term projections for the concentration of the main greenhouse gases (radiative forcing gases). Emissions trajectories depend mainly on political and economic choices and are therefore referred to as RCPs (Representative Concentration Pathways). Each scenario presents a concentration increase curve that results in a different level of radiative forcing: 2.6, 4.5 or 8.5 W m-2.
Climate models are extremely complex and are constantly changing. A set of 18 models are available and used to predict the distribution of forest species.
The forest distribution model used here is the IKS model, implemented in the ClimEssence (https://climessences.fr/) platform. The model was subjected to an extensive calibration based on a very large dataset on a European scale (NBFI data from most EU countries, including Romania).
The IKS model is a bioclimatic compatibility model, with the aim of predicting the presence or absence of a certain forest species depending on limiting climatic parameters. The presence-absence estimates are based on three indicators: the annual water deficit, the annual minimum temperature and the annual sum of degree-days.
The IKS model is used here to model the distribution of species under current conditions, then in future climatic conditions, such as the two scenarios RCP4.5 and RCP8.5. The model makes it possible to distinguish between the distribution margin and the distribution centre. For each species, three areas are always distinguished: the areas located in the center of the distribution, the distribution margin and, finally, the exterior, where the species is supposed to be absent.

The dynamic maps show 9 areas: 3 areas where the species is currently present, 3 areas where it is at the limit of its distribution, 3 areas where it is absent. For each of the current zones, there are three future zones: either inside the compatibility zone, at the edge, or outside the compatibility zone.

RCP4.5 scenario
The distributions are based on future climate data, using the average of the predictions of 18 climate models. The RCP4.5 scenario is considered an average scenario, but predictions for average annual temperatures still show an increase of 2.15ºC by 2070 compared to current temperatures.

RCP8.5 scenario
The RCP8.5 scenario is considered harsher, and predictions for average annual temperatures show an increase of 3.6ºC by 2070.