Vegetation Ecology of Socotra

ISBN-13: 9789401784597 / Angielski / Miękka / 2014 / 382 str.

Gary Brown; Bruno Mies

Opis

Although the unique flora of the Socotra Archipelago with its high degree of endemism has received much attention recently, little information is available on the vegetation and related ecological aspects. Based on their extensive field experience of the region, the authors have assimilated a vast amount of knowledge to produce this book, which gives a detailed insight into the plant ecology of Socotra, designated as a World Heritage Site by UNESCO in 2008. The book is divided into seven chapters. After a brief introduction and overviews of important abiotic features, various aspects of the vascular flora are presented in Chapter 4, together with accounts of the bryophyte and lichen flora. Ecology and adaptive strategies of the plants are dealt with in Chapter 5, and Chapter 6 gives a concise description of the main vegetation units. Finally, important management issues of the vegetation are discussed, an essential topic to ensure preservation of the natural heritage of the archipelago.

Spis treści

Preface.- Acknowledgements.- 1. Introduction.- 2.- Topography, Climate and Soils.- 2.1. Introduction.- 2.2. Topography.- 2.3. Climate and weather patterns.- 2.4. Soils.- 3. Geology.- 3.1. Introduction.- 3.2. General geology and structure.- 3.3. Basement rocks.- 3.4. Triassic and Jurassic strata.- 3.5. Cretaceous strata.- 3.6. Tertiary strata.- 3.7. Quaternary deposits.- 3.8. Brief geology of the ancillary islands.- 3.9. Brief tectonic and climate history of the region.- 4. Flora and Biogeography.- 4.1. History of botanical exploration.- 4.2. Vascular plants.- 4.2.1. General attributes of the flora of Socotra.- 4.2.2. Characteristic distribution patterns.- 4.2.3. Endemism.- 4.2.3.1. Endemic taxa.- 4.2.3.2. Palaeoendemics and neoendemics.- 4.2.4. Origins of the Socotra flora and colonisation of the islands.- 4.2.4.1. Dispersal and vicariance.- 4.2.4.2. Long-distance dispersal.- 4.2.4.3. Examples of dispersal and vicariance in the flora of Socotra.- 4.2.4.4. Dispersal and vicariance in the fauna of Socotra.- 4.2.4.5. Invaders and colonizers.- 4.3. Ferns.- 4.4. Non-vascular cryptogams.- 4.4.1. Bryophytes.- 4.4.2. Lichens.- 5. Ecology and Adaptive Strategies.- 5.1. Introduction.- 5.2. Adaptation of plants to desert ecosystems.- 5.2.1. Photosynthetic pathways.- 5.2.2. Plant water relations.- 5.2.2.1. Leaf and stem adaptations to counteract low water potentials.- 5.2.2.2. Root systems.- 5.2.3. Energy balance.- 5.2.3.1. Energy balance and leaf morphology 5.2.3.2. Energy balance and water cycling.- 5.2.3.3. Leaf anatomy, reflectance, orientation.- 5.3. Adaptation of plants to highly saline ecosystems.- 5.4. Adaptation of plants to high-montane ecosystems.- 5.5. Life and growth-forms.- 5.5.1. Raunkiaer life-form classification.- 5.5.2. Growth-form classification of Socotran plants.- 5.5.2.1. Drought-deciduous trees.- 5.5.2.2. Drought-deciduous shrubs and dwarf shrubs.- 5.5.2.3. Evergreen trees and shrubs.- 5.5.2.4. Phreatophytes.- 5.5.2.5. Aphyllous spartinoid shrubs.- 5.5.2.6. Stem and leaf succulents.- 5.5.2.7. Caespitose graminoids.- 5.5.2.8. Stoloniferous perennial graminoids.- 5.5.2.9. Cliff-dwelling perennials.- 5.5.2.10. Cushion and mat-forming plants.- 5.5.2.11. Lianas.- 5.5.2.12. Epiphytes.- 5.5.2.13. Ephemerals.- 5.5.2.14. Parasitic plants.- 5.5.3. Life-form analysis.- 5.6. Adaptive strategies.- 5.6.1. Relating net carbon gain to environmental stress in arid ecosystems.- 5.6.2. Plant strategies in arid ecosystems.- 5.6.3. r/K-selection theory and the three-strategy CSR classification system of Grime.- 5.7. Pollination.- 5.8. Seed dispersal and germination.- 6. Vegetation.- 6.1. General comments on the vegetation.- 6.2. Broad vegetation classification.- 6.3. Vegetation of the different altitudinal belts.- 6.3.1. Coastal vegetation types.- 6.3.1.1. Sea-grass beds.- 6.3.1.2. Sandy beaches, coastal sand sheets and dunes.- 6.3.1.3. Mangroves: Avicennia marina community.- 6.3.1.4. Salt-marsh and sabkha vegetation: Arthrocnemum macrostachyum community.- 6.3.1.5. Salt-marsh and sabkha vegetation: Limonium sokotranum community.- 6.3.1.6. Other salt-marsh and sabkha vegetation.- 6.3.2. Vegetation of the coastal plains.- 6.3.2.1. Croton socotranus community.- 6.3.2.2. Tephrosia apollinea stands.- 6.3.2.3. Acacia edgeworthii community.- 6.3.2.4. Pulicaria stephanocarpa community.- 6.3.2.5. Indigofera pseudointricata–Salsola spinescens community.- 6.3.2.6. Limonium paulayanum community.- 6.3.2.7. Other vegetation types of the plains.- 6.3.3. Vegetation of the wadis at lower and middle altitudes.- 6.3.3.1. Characteristic species and assemblages of the wadis.- 6.3.4. Vegetation of lower-altitude rocky slopes.- 6.3.4.1. Adenium obesum community.- 6.3.4.2. Dwarf stem succulent communities.- 6.3.5. Vegetation of the cliffs and crevices.- 6.3.5.1. Characteristic species and assemblages of the cliffs.- 6.3.6. Vegetation of the mid-elevation plateaus and gentle slopes.- 6.3.6.1. Buxanthus pedicellatus–Dracaena cinnabari woodland of the mid-elevation limestone plateaus.- 6.3.6.2. Other vegetation types.- 6.3.6.3. Lower montane woodland.- 6.3.7. Vegetation of the montane and high-montane cloud zone.- 6.3.7.1. Cephalocroton socotranus community.- 6.3.8. Other montane vegetation types.- 6.3.9. Vegetation of the high-montane granite peaks.- 6.3.9.1. Leucas hagghierensis–Pittosporum viridiflorum community.- 6.3.9.2. Helichrysum–Hypericum dwarf shrub communities.- 6.3.10. Vegetation of wet flushes and other semi-aquatic habitats.- 6.4. Vegetation map of Socotra.- 6.5. Potential natural vegetation.- 7. Environmental Management.- 7.1. General introduction.- 7.2. Habitat degradation and desertification.- 7.3. Direct causes of ecosystem degradation.- 7.3.1. Effects of overgrazing.- 7.3.2. Soil erosion.- 7.3.3. Wood-collecting and deforestation.- 7.3.4. Infrastructure development.- 7.3.5. Impacts of drought.- 7.3.6. Potential impacts of climate change.- 7.3.7. Water extraction.- 7.3.8. Invasive species.- 7.3.9. Rubbish.- 7.4. Regeneration of the natural vegetation.- 7.4.1. Restoration.- 7.4.2. Native plant production.- 7.5. Conservation of the flora of Socotra.- 7.5.1. The conservation of Dracaena cinnabari.- 7.5.2. The conservation of Boswellia elongate.- 7.6. Coordination of conservation efforts.- 7.6.1. Conservation zoning plan.- Appendix 1. List of vascular plant species of the Socotra archipelago.- Appendix 2. List of bryophytes of Socotra.- Appendix 3. List of lichens of Socotra.- References.- Index

Blurb

The Socotra Archipelago is a regional biodiversity hotspot with a high degree of endemism, and it is for this reason that it is often referred to as the “Galápagos of the Indian Ocean”. Although its unique flora has received much attention recently, little information is available on the vegetation and related ecological aspects. Based on their own extensive field experience of the region, the authors have assimilated a vast amount of knowledge to produce this book, which gives a detailed insight into the plant ecology of Socotra, designated as a Biosphere Reserve by UNESCO in 2003, and as a World Heritage Site in 2008.

 

The book is divided into seven chapters. After a brief introduction and overviews of important abiotic features, various aspects of the vascular flora are discussed in Chapter 4, such as biogeography, endemism, dispersal and vicariance, followed by summaries of the bryophyte and lichen flora, including up-to-date checklists of species. Ecology and adaptive strategies of the plants are outlined in Chapter 5, with an emphasis on the arid-land ecosystems, and Chapter 6 gives a concise description of the main vegetation units along an altitudinal gradient, from sea-level to the high mountain peaks at ca. 1550 m. At lower altitudes, desert communities and succulent scrub vegetation dominate, but with increasing elevation, woodland and forest become more prevalent. The final chapter addresses important management issues for the flora and vegetation, issues which, given the rapidly increasing anthropogenic pressures, are critical to preserving as much of the natural heritage of the archipelago as possible. Throughout the book, comparisons are made with the situation in other parts of the world, and in particular, the close affinities with Dhofar in southern Oman and the Canary Islands off the coast of West Africa are underlined.