Comparison of the Climate Change Tolerance of Native and Non-Native Species Used or Potentially Used as Ornamentals in Mediterranean Areas

Abstract

As a consequence of climate change, temperature and rainfall regimes are being modified, threatening the survival of the current gardening concept in many areas of the world. This situation highlights the need to investigate the potential of other species, especially in more sensitive areas such as the Mediterranean Basin. The aim of this research is to study the resilience of adapted species to promote sustainable gardening. To achieve this, seven species belonging to three families (Amaranthaceae, Lamiaceae and Asteraceae) used or potentially used as ornamentals were selected to compare their tolerance at the germinative stage to different levels of temperature (10 °C to 35 °C) and water stress created by PEG 6000 (−0.10 MPa to −2.5 MPa). Germination percentage, mean germination time, base temperature, thermal time, base water potential and hydrotime were calculated. The results showed a good response to high temperature and low osmotic potential in most of the species, and germination even increased under certain stress levels. Salsola oppositifolia presented by far the best results in terms of germination under high-water-stress conditions and the second best at high temperatures. The extraordinary response of Celosia argentea, an alien species, highlighted the risk of it becoming an invasive species.