The key role of accompanying species in the response of the critically endangered Naufraga balearica (Apiaceae) to climatic factors

Abstract

This study addressed the response of Naufraga balearica, a critically endangered plant endemic to Mallorca (Balearic Islands, western Mediterranean Basin), and its adjacent community to climatic factors by assessing whether climate influences plant cover in N. balearica, including oscillation associated with seasonality, and whether the accompanying species influences its response to climatic factors. The cover of N. balearica and two other accompanying species (Erodium reichardii and Dactylis glomerata) were estimated quarterly from permanent plots over 12 years. The original time series of plant cover and climatic variables were transformed to obtain a smoothed and a detrended time series. The tendency of all variables was assessed using a simple linear regression of the smoothed series. The relationship among plant cover and climatic variables were tested by correlation. Naufraga balearica showed a declining trend, while E. reichardii and D. glomerata experienced a stable and an increasing population trend, respectively. However, all species showed an annual cover oscillation with a similar pattern. A new bioclimatic index combining temperature and precipitation variables was a good predictor although extreme meteorological events substantially altered the trends and patterns of the three species. The response of N. balearica to climatic factors, including extreme weather events, is exacerbated by the presence of other species, mainly those grasses with caespitose growth form and with a faster response to the changing environmental factors. In a climate change scenario, N. balearica would be limited to the shadiest grass-free zones. The current situation emphasises the importance of taking conservation action to guarantee the species conservation.