Distribution, reproductive potential and conservation assessment of the rare and endemic Dionysia mira in the Hajar Mountains, Sultanate of Oman

Abstract

Dionysia mira (Jaub. & Spach.) Wendelbo is endemic to the northern mountains of Oman, where it is restricted to a few isolated populations in the eastern and western Hajar Mountains; the extent of populations has not been accurately documented. Here we investigate the population size and distribution, habitat preferences, reproductive biology and potential threats, and ex‐situ conservation initiatives at Oman Botanic Garden are discussed. In 2017, 4045 flowering plants were recorded; of which 3595 were concentrated around the village of Shnoot on Jabal Al Akhdar in the western Hajar mountains. Plants are found between 1700 m and 2500 m a.s.l. on north facing limestone gravel slopes and fissures on vertical outcrops and cliff faces within Sideroxylon mascatense – Olea europaea and Teucrium mascatense – Juniperus seravschanica vegetation communities. Plant density within the core population at Shnoot is 52 plants/100 m2; 46% of which were mature plants, 32% semi‐mature and 15% seedlings. The mean number of seeds per plant was 14 000; bee‐flies (Bombyliidae) are suggested as likely pollinators. Using freshly collected seeds under controlled conditions between 10°C and 30°C a 90% germination rate was recorded; there was no difference in the germination rates between stratified and non‐stratified seeds. Dionysia mira is under threat from predicted climate change scenarios in the region and habitat loss through widespread development within its core range. Long‐term ex‐situ conservation programme at Oman Botanic Garden maintains a seed and living plant collection.