Assessing the Effects of Drought and Temperature on the Establishment of Juniperus seravschanica Saplings in Northern Oman

Abstract

Climate change poses a serious threat to the survival and distribution of Juniperus seravschanica in the northern mountains of Oman. A better understanding of this species’ responses to environmental changes is essential if the potentially harmful effects of climate change are to be mitigated. One such step is to understand how changes in climate may influence the growth of juniper saplings. Two- and five-year-old saplings were grown under different temperature and watering regimes to determine effects on establishment and growth. Under an optimum growing temperature, reducing water to 50 per cent and 25 per cent of the optimal irrigation regime significantly decreased the growth of juniper saplings. In field studies, saplings re-introduced to three different altitudinal locations showed varying rates in establishment success and growth. Both two-yearold and five-year-old saplings established better at higher altitude. Overall, survival rates were considerably better with the transplantation of five-year-old rather than two-year-old saplings.Applying irrigation improved the survival of two-year-old stock when grown at the lowest altitude, but rates were not always significantly different from other treatments. Apical extension growth was found to be reduced at higher altitude, indicating that temperature influences the growth of juniper saplings. However, it was the combination of drought and high temperatures that reduced the growth of non-irrigated saplings at lower altitudes. These preliminary results suggest there is potential to artificially re-introduce juniper saplings to their natural habitat as part of a conservation programme, but more time is required to judge the success of the transplanting initiative when dealing with slow-growing trees such as juniper.