Possible effects of climate change on the germination of Mediterranean plants at different elevations in İzmir-Bozdağ

Temperature and drought are two of the main environmental factors controlling germination. Climate change affects germination processes by changing the temperature and humidity conditions to which seeds are exposed. In this study, it was aimed to determine the possible effects of climate change on the germination of plant taxa characteristic for different vegetation types and growing naturally in different orders in Bozdağ region located within the borders of Izmir province. For this purpose, 6 different locations belonging to two different elevation groups were selected in the region. The first group included 3 different points with low altitude and the second group included 3 different points with high altitude. Field studies were carried out during the vegetation period of 2022 and 47 populations of 33 plant taxa were sampled in total. The collected seeds were subjected to different temperatures and different drought severities and the germination responses of the seeds were examined under these conditions. In the temperature experiment, four different constant temperatures (15, 20, 25, 30°C) and three different alternating temperatures (20/10, 25/15, 20/30°C) were applied. For the drought experiment, a drought severity range of 5 different values (-0.0625, -0.125, -0.25, -0.25, -0.5, -0.75 MPa) was created using PEG 6000 solution and the germination responses of the seeds were examined. Climatic data for the study area were obtained from the UKESM1-0-LL model in the CHELSA global climate database by selecting the SSP5 scenario. Using these data, past, present and possible future climate change scenarios (1981-2010, 2011-2040, 2041-2070 and 2071-2100) were presented. Statistical analyses of the obtained data were performed using Excel and R programs. According to the climate change scenarios created, it is assumed that at the end of the 119-year period between 1981 and 2100, the total annual precipitation will decrease by approximately 40.6 mm and 46.1 mm in low and high elevation areas, respectively, while the average annual temperature will increase by approximately 7 °C in both elevation groups. According to the same scenario, at the end of the 119-year period, the drought period is assumed to be extended by approximately 6 weeks in low-altitude areas, while this period is assumed to be extended by approximately 5 weeks in high-altitude areas. The conclusions of the study are as follows: a) germination responses to temperature and drought were more variable in families with a large number of taxa. This suggests that germination responses to temperature and drought may be species-specific and independent of higher taxonomic units such as families, b) the effects of elevation difference on germination at the population level were also found to be species-specific, c) In the most pessimistic climate change scenario (SSP585), under high temperature and drought conditions in İzmir Bozdağ, the studied taxa belonging to the Poaceae and Fabaceae families are likely to persist against climate change, while taxa with low temperature tolerance such as Papaver sp and Allium proponticum may not be able to persist.