The use of indigenous plants in landscape of Saudi Arabia
Throughout the world increasing use is being made of native plants in urban landscapes, both to preserve regional visual character, conserve native biodiversity and to reduce energy inputs in the urban landscape. In Saudi Arabia most designed urban landscapes employ non indigenous plants. This use of exotic plants is problematic as these species require considerably more water and maintenance, This study establishes a basic understanding of the use of twenty Saudi indigenous plants for semi-nature landscape. We have identified the suitable methods for breaking dormancy and the germinating of these species. We have also selected the most appropriate time for germination by defining the optimal germination temperature of each species. In general most of these species were found to have adaptation to cope with water stress and salinity. For most of these species the maximum germination percentage was at the temperatures between 20 T and 30 T. Competition is one of the most important factors which controls the success of a sown community. Therefore we have investigated the establishment of species in mixture under simulated Saudi conditions using microcosm competition experiments within communities of native species. The results show that in the survival of sown species soil moisture stress was the major factor determining survival. Greater competition for moisture was demonstrated in the weedy treatment. It is clear that weeds would be a problem in practice in the field in dry climate. In terms of the growth of these species, at high water stress; weeds are less competitive than under low water stress. Therefore on very weedy sites irrigation would not be valuable in practice. Cutting may be helpful for the establishment of these species within a community in weedy sites. Overall, the results of these studies demonstrate that these twenty Saudi indigenous species could be used in landscape within the target species method where plants are grown individually or in-groups of one or two species. Also they can be used within the target community method for creating communities in practice in semi-natural landscape projects in Saudi Arabia.