Understanding the effects of climate change is one of the most challenging goals for biodiversity conservation. The forests of Andalusia, in Southern Spain, are part of an important Mediterranean Basin biodiversity hotspot. However, great changes in climate are expected to occur in this region, and there is an increasing need to assess the vulnerability of its vegetation. We assess the vulnerability of twelve forest types in the region that are included in the European Directive 92/43/EEC as Habitats of Community Interest (HCI). HCI are natural habitat types which are in danger, have a small natural range, or present an outstanding example of a biogeographical regions in the European Union. We assessed vulnerability by analyzing the climate exposure level of each forest type under two global climate models (MRI-CGCM3, which predicts warmer and wetter conditions, and MIROC-ESM which predicts hotter and drier conditions), two emission scenarios (RCP4.5, a representative concentration pathway that predicts stable emissions of CO₂, and RCP8.5, that predicts the highest CO₂ emissions) by the mid- and end-century time periods. The vulnerability analysis also includes the sensitivity and adaptive capacity of the dominant tree species which compose each forest type. An overall vulnerability score was calculated for each forest type, model, scenario and time period. High-elevation forest types and those with high moisture requirements were more vulnerable to climate change, while forest types dominated by more thermophilic species were less vulnerable and more resilient. The worst climate impacts were predicted in the MIROC-ESM model and RCP8.5 scenario by the end of the century (2070-2100), while the least climatic stress was obtained in the MRI-CGCM3 model and RCP4.5 scenario by the mid-century (2040-2070), which still shows high potential stress for most forest types. By the end of the century, the climate exposure of the entire forest domain will range between 32 % in the least stressful situation (MRI-CGCM3 and RCP4.5), and 98 % in the most climatically stressful situation (MIROC-ESM and RCP8.5). However, the effects of climate change will be perceptible by the mid-century, with most of the HCI forest types suffering climate stress. The "Andalusian oak forest" and the "Corylus wet forest" types were the most vulnerable to climate change, while the "Mediterranean pine forest", the "Olea and Ceratonia forests" and the "oak forests" were the least vulnerable. This assessment identifies the vulnerable forest types to climate change in the south of the Iberian Peninsula, and provides context for natural resource managers in making decisions about how to adapt forests to the impacts of climate change.

The westernmost European nucleus of the 5220* Habitat of Community Interest (HCI) is located in the province of Málaga (Andalusia). In this area, the 5220* HCI is characterized by the presence of scrublands of Gymnosporia senegalensis subsp. europaea. This is a relict species in Europe, with inhabits only in the southeast of the Iberian Peninsula. The westernmost Iberian nuclei of the 5220* HCI are constituted by three isolated nuclei (Málaga–Rincón de la Victoria; Torremolinos; and Pizarra). These nuclei have been only partially mapped. The objectives were: to map the 5220* HCI characterized by G. senegalensis subsp. europaea in detail; to evaluate its degree of conservation (DC); and to identify the chronosequences of the evolution of this habitat from 1957 to 2021, and its fragmentation. Our results have contributed to generating a 1:10,000 scale cartography of the habitat. In general, the DC obtained was from good to excellent. With an excellent DC value, one inland locality (Pizarra) was highlighted. However, the highest reduction in the value of DC was observed in the localities of Torremolinos and Málaga–Rincón de la Victoria which, in addition, have reduced the area of occupancy (AOO) and are fragmented. It is important to note that some areas of Málaga–Rincón de la Victoria reached excellent values of DC, indicating the need to carry out protection.

Climate change is affecting Mediterranean climate regions, such as California. Retrospective phenological studies are a useful tool to track biological response to these impacts through the use of herbarium-preserved specimens. We used data from more than 12,000 herbarium specimens of 29 dominant native plant species that are characteristic of 12 broadly distributed vegetation types to investigate phenological patterns in response to climate change. We analyzed the trends of four phenophases: preflowering (FBF), flowering (F), fruiting (FS) and growth (DVG), over time (from 1830 to 2023) and through changes in climate variables (from 1896 to 2023). We also examined these trends within California’s 10 ecoregions. Among the four phenophases, the strongest response was found in the timing of flowering, which showed an advance in 28 species. Furthermore, 21 species showed sequencing in the advance of two or more phenophases. We highlight the advances found over temperature variables: 10 in FBF, 28 in F, 17 in FS and 18 in DVG. Diverse and less-consistent results were found for water-related variables with 15 species advancing and 11 delaying various phenophases in response to decreasing precipitation and increasing evapotranspiration. Jepson ecoregions displayed a more pronounced advance in F related to time and mean annual temperature in the three of the southern regions compared to the northern ones. This study underscores the role of temperature in driving phenological change, demonstrating how rising temperatures have predominantly advanced phenophase timing. These findings highlight potential threats, including risks of climatic, ecological, and biological imbalances.

Melinis repens subsp. repens is an annual herb native to Africa and southwestern Asia. In 2008, this species was detected growing in road verges and showing a reduced occupancy area of 6 km² in a natural area of the southern Iberian Peninsula in the province of Malaga (Andalusia, Spain). The rest of the existing European records of this species comes from the Czech Republic, the Italian Peninsula, and Great Britain and can be considered casual. Furthermore, this species has become naturalised in Sardinia. The aim of this work is to study the invasion status, habitats, potential impacts, invasive behaviour, and pathways of introduction of Melinis repens subsp. repens in the southern Iberian Peninsula (Spain) to contribute to the control of this species. This species was most probably introduced into Europe for ornamental, fodder, or slope stabilization purposes. Our field work revealed this species has become naturalised in several habitats of Malaga and Granada provinces (Andalusia) occupying an area of 263 km² in 2021. It behaves as a pioneer species that colonizes disturbed road margins and occurs in the same habitat as Cenchrus setaceus. Melinis repens subsp. repens can become dominant in natural EUNIS habitats and can also occupy cultivated areas. Because of the high occupancy area detected, and because the species has been assigned to the European Union List of Invasive Alien Plants based on the EPPO prioritization process, this plant should be considered the object of a control programme and its use should be legally prohibited in Spain, and more largely in European Mediterranean areas.

Herbarium specimens have proven useful for assessing phenological responses to climate change. Using preserved specimens, we analysed the changes in day of year (DOY) for four phenophases: three reproductive (preflowering, flowering, fruiting) and one vegetative (growth). We conducted phenological analysis across bioclimatic belts (thermotypes) from the Rivas–Martinez classification and across 77 taxa present in the Baetic Ranges of the southern Iberian Peninsula. Taxa were characteristic, common, or endemic species from Habitats of Community Interest (HCI) under the European Directive 92/43/EEC. Phenological shifts were assessed using two approaches: long-term trends in DOY with time and relationships with historical climate variables related to temperature and precipitation. At the thermotypes level, flowering advanced consistently over time and with increasing temperatures, showing homogeneous responses and suggesting a weakening of altitudinal differentiation. In contrast, growth exhibited thermotype-specific trends, with stronger advances at high elevations, while preflowering and fruiting showed little or no sensitivity to time or climate variables. At the species level, 31% of taxa showed phenological changes over time in the Baetic Ranges (−3.6 days/decade for reproductive and −5.6 days/decade for vegetative phenophases). However, 97% of taxa showed significant relationships with increasing temperatures and decreasing precipitation, particularly with mean annual temperature (−12.7 days for reproductive and −14.3 days for vegetative phenophases per increased °C). These phenological changes could hinder reproductive and vegetative success by causing mismatches with other ecosystem role-players. As the Mediterranean is expected to become warmer and drier, our findings indicate a potential threat to HCI in the southern Mediterranean.