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Thursday, 19 January 2017
Large old trees need more conservation attention: A case of Tamarix aphylla in the arid deserts of the United Arab Emirates
Published Date
Journal of Asia-Pacific Biodiversity 30 June 2015, Vol.8(2):183–185,doi:10.1016/j.japb.2015.04.006 Open Access, Creative Commons license,Funding information Short communication
Author
Tamer Mahmoud a
Sanjay Gairola a,,
Ali El-Keblawy b
aSharjah Seed Bank and Herbarium, Sharjah Research Academy, Sharjah, United Arab Emirates
bDepartment of Applied Biology, Faculty of Science and Sharjah Research Academy, University of Sharjah, Sharjah, United Arab Emirates
Received 27 February 2015. Revised 21 April 2015. Accepted 27 April 2015. Available online 5 May 2015.
Abstract Large old trees are often recognized for the provision of variety of ecosystem services to humanity. This paper reports the existence of a large oldTamarix aphylla(L.) Karst. tree in the Hamriyah area of Sharjah, the United Arab Emirates. Existence of such keystone structures spans many human generations and they become a historic link between the generations. Therefore, protection and recognition of more culturally, historically, and ecologically important trees by establishing a comprehensive tree list are crucial. Keywords
Large old tree
Protection
Tamarix aphylla
The United Arab Emirates
Introduction
Large old trees are prominent keystone structures in many landscapes worldwide and are well recognized for the provision of variety of ecosystem services to humanity. The ecological roles of old trees in improving and maintaining the quality of water and soil, mitigating the impact of environmental pollution, carbon sequestration, regulation of microclimate, providing habitat for wildlife, providing recreational and spiritual values, among other values are widely acknowledged (Blicharska and Mikusiński, 2014 and Stagoll et al., 2012). Indeed, each tree has a rhythm in nature, a symbiotic relationship with other organisms, and maintains ecological balance, all of which are crucial for ecosystem integrity; in addition, each tree has a historical, spiritual, and religious significance as well as significant relations with humans. Across the world, due to anthropogenic pressures and environmental changes, the rapid decline of such trees in different landscapes is having a serious impact on ecosystem integrity and biodiversity, and therefore, has caused great global conservation concern. It is thus important to protect existing trees and promote the planting of native trees in different locations in the country. Trees do far more good than harm and we have a collective responsibility to conserve them. Therefore, the potential threats to old trees should be identified and they need to be carefully managed and preserved. To ensure the survivability of old trees, the most important initial action is to install a fence around them and extend it beyond the canopy of the mature trees, because natural regeneration is most likely to occur.
Conservation of native trees has received some attention from the environmental authorities in the United Arab Emirates (UAE). Several decrees have been issued during the past few decades to forbid destruction of any individual native trees, especially Prosopis cineraria and Ziziphus spina-christi. This resulted in the increase in the number of old trees of these species, especially in residential areas. However, there is very limited information about the status of old trees in the UAE and other Arab Gulf regions. According to The National Newspaper (15 August 2013), the Municipality of Al-Fujairah conducted a survey on the number of large old trees in Dibba and recorded a total of 63 trees that are > 200 years old. These ancient trees belong mainly to Acacia tortilis, Z. spina-christi, and P. cineraria. This shows that the recognition of the values of old large trees in the UAE is gaining more attention by researchers and conservationists. The crucial role of old trees in the harsh deserts necessitates conducting more accurate studies, such dendrochronology (or tree-ring dating), which can date the time at which tree rings were formed, in many types of wood, to the exact calendar year (Jacoby 1989). Such studies should be encouraged for effective conservation and management of big and relic trees in the UAE and Arab Gulf regions. In this paper, we report the existence of one of the oldest large trees of Tamarix aphylla (L.) Karst. and highlight the importance of the conservation of old trees in the arid environment of the UAE.
Materials and methods
During the floral surveys conducted by the Sharjah Seed Bank and Herbarium (SSBH) during the year 2013–2015, a large old tree of T. aphylla (L.) Karst. was recorded from the Hamriyah area (N: 25.480896° and E: 55.498159°) of the Emirate of Sharjah, UAE. The geographic coordinates of the site near the tree were recorded. Girth at breast height of the tree was measured by tightly wrapping a tape around the tree’s main trunk. The height was measured using a Nikon Laser Rangefinder, Forestry 550 (Nikon Vision Co. Ltd. Japan) Identity of the species was confirmed by consulting relevant floral literatures and with the help of plant taxonomists. The specimens were processed and deposited in the SSBH (Sharjah, UAE).
Results and discussion
Our measurements for the encountered old T. aphylla indicate that it is among the largest old trees in the UAE. The height of this tree is approximately 14.2 m with 4.2-m girth (Figure 1). Having such a large old tree in the hyperarid desert of the Arab Gulf region is a rare event, as the stressful conditions in the region often limit the growth of trees and human interference destruct big trees (Tourenq and Launay 2008). T. aphylla is one of the most drought-tolerant trees in the Arabian deserts. Since, the transpiration rate of this species is reported low (Davenport et al 1982), it can survive with very limited amount of water under dry and extremely hot conditions of the arid deserts of the UAE. It is one of the few trees that is able to grow on loose sand dunes and tolerate salinity and drought stresses. In addition, it has the ability to stabilize loose sand dunes. Under the very harsh desert environment, the key ecological functions of the large old trees are provision of a distinct microclimate (as these trees provide shade and help in lowering temperatures during hot weather) and beautifying landscapes. In addition, they have greater importance for ecosystem integrity and biodiversity. In the current conservation scenario, the old trees are considered as critical organisms and ecological structures in forests, woodlands, savannas, agricultural, and urban environments (Le Roux et al., 2014 and Lindenmayer et al., 2012). Recently, Blicharska and Mikusiński (2014) pointed out that large old trees easily awaken emotions, appeal to aesthetic sentiments, and are often perceived as important landmarks.
Figure 1. A, A large old Tamarix tree growing at the Hamriyah coast (UAE); B, A flowering twig of this tree.
During our subsequent visit in the year 2015, we observed that for protecting this large old tree from destruction, the municipality concerned has installed a fence around it (Figure 2). Fencing could be an effective way to reduce damage to historical trees such as the one reported here. The elderly people living in this area revealed that earlier generations have seen the tree as big as it is today. However, it is important to determine the age of old trees by some accurate methods such as tree-ring dating. Local people mentioned that their ancestors used this tree as a shelter during the hot days and in celebrating their special events. Interestingly, the residents emphasized the cultural importance of this tree that links them with earlier generations. They recognize this tree as a vital part of their history and heritage, and stressed that this living monument should receive more attention as a heritage and cultural symbol. It is well-known that large old trees need a long time to develop old-growth characteristics; thus, their existence spans many human generations and eventually they become a historic link between the generations. Therefore, acknowledging people’s perceptions toward old trees could be critical for policy makers, as these trees are among the oldest and most complex organisms in their ecosystem and have great ecological and cultural significances.
Figure 2. Fencing around the Tamarix tree to ensure protection.
Interestingly, the exceptional longevity of trees is an additional unique feature, which in some cases exceeds even thousands of years (Blicharska and Mikusiński 2014). In the literature, there are some old trees of bristlecone pine (Pinus longaeva) reported from the White Mountains of California, CA, USA whose lifetime has spanned the building of the pyramids, and certain olive trees planted in the Garden of Gethsemane that may date from the time of Christ. In Asia and Africa, trees such as peepal (Ficus religiosa) or banyan (Ficus benghalensis) are often referred in historical background, worshiped, and widely protected as a keystone resource. A Bo tree in Sri Lanka is known to be 2300 years old, under whose branches Buddha is said to have gained spiritual enlightenment. Similarly, an oak tree in southern Sweden is > 1000 years old (Blicharska and Mikusiński 2014).
Apart from government policies and legislations, there is a need to undertake a public awareness drive to preserve aesthetical, cultural, and ecological significance of large old trees and their conservation. For the UAE, recently Goumbook and its local partners have launched the “Give a Ghaf” program to raise public awareness about the Ghaf (P. cineraria) and its values, while encouraging people to plant them. Therefore, using native trees in urban landscaping would be a good option for conserving limited water resources in the UAE while it also gives a chance to have more old trees with time.
Similarly, for effective conservation and management of large old trees, there is a need to formulate a national group for protecting old trees and growing native trees in urban areas. When needed, a careful policy for replacement of existing exotic trees with similar native trees should be implemented. In this context, native trees such as Z. spina-christi and P. cineraria, which are tolerant to abiotic stresses, such as drought, salinity, and heat, and resistant to most kinds of pests, should be recommended for landscaping urban areas with hyperarid environment in the Arab Gulf countries.
There is a strong need for incorporating the social and cultural significance of large old trees in conservation policy, because it will strengthen their conservation by highlighting the potential synergies in protecting ecological and social values. We need to monitor the performance and decline of heritage trees in urban areas in the UAE. Although the Tamarix trees have a very limited use in urban greenery in the UAE today, it has the potential to increase the species diversity of the current urban tree population in urban paved sites, where the need for a greater diversity is highest.
Conclusion and way forward
In the face of escalating threats to world’s biodiversity, there is a pressing need for accelerated conservation efforts to protect the large old trees in different landscapes for future generation. These trees are providing key ecological services to all ecosystems. The first step toward conserving and restoring these large old trees is to encourage people to recognize their ecological importance, wildlife habitat values, and their religious, historical, medicinal, and emotional aspects. Consequently, public participation would help in conservation of old trees. Moreover, protection and recognition of more culturally, historically, and ecologically important trees by establishing a comprehensive “Tree List” are crucial. This list should include all large old trees not only in the UAE, but also in all Arab Gulf countries, as they are all suffering from great environmental stresses and human disturbances. As already predicted by other researchers, if old trees are lost and their populations continue to collapse, the ecological, historical, and landscape roles of these keystone structures will disappear. Therefore, we need to take every possible action to protect large old trees in the region and raise awareness about their key roles in supporting biodiversity.
Acknowledgments
The authors thank the Sharjah Research Academy for encouragement and support.
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