Dissertationes Botanicae Band 393

Christian Stierstorfer The Vascular Vegetation in the Forest Belt of El Hierro ()

with 110 figures, 34 tables, 20 colored plates and 2 tables on 1 folder

J. CRAMER in der GebrQder Borntraeger Verlagsbuchhandlung BERLIN • STUTTGART 2005 Content 3

Content

Preface and acknowledgements 7 1 Introduction 11 2 Geography and history of El Hierro 14 2.1 Geographic situation, topography and toponymy 14 2.1.1 Physical regionalisation and settlements 14 2.1.2 Toponyms 15 2.1.3 Toponyms and 21 2.2 Geomorphology and geology 23 2.2.1 Age and origin of El Hierro 23 2.2.2 Present geology of El Hierro 26 2.3 Soils 27 2.3.1 Order Inceptisols and Order Aridisols 28 2.3.2 Order Entisols 28 2.3.3 Order Andisols 29 2.3.3.1 Suborder Torrands 29 2.3.3.2 Suborder Vitrands 30 2.3.3.3 Suborder Udands 32 2.3.3.4 Suborder Ustands 33 2.4 Climate, weather and bioclimatic classification 33 2.4.1 The different weather regimes 35 2.4.2 Climate and weather on El Hierro 37 2.4.2.1 Precipitation 37 2.4.2.1.1 Rain 38 2.4.2.1.2 Fog precipitation 49 2.4.2.2 Wind and clouds 52 2.4.2.3 Temperature and insolation 54 2.4.2.4 Humidity, aridity and evapotranspiration 57 2.4.3 Bioclimatic classification and the potential natural vegetation (PNV) 58 2.5 History, land use and nature conservation 62 2.5.1 Colonisation and population 63 2.5.2 Land use 64 2.5.3 Historical references to flora and vegetation 70 2.5.3.1 The forests 70 2.5.3.2 The Arbol Santo (Garoe) 74 2.5.4 Nature conservation 76 2.6 History of botanical investigation and current knowledge 78 4 Content

3 Methods 81 3.1 The study area 81 3.2 Thefieldwork 82 3.3 Data processing, phytosociological tables, maps and graphics 87 3.4 Phytosociological order and classification 88 3.5 Digression regarding the criticism of phytosociology 93 3.6 Abbreviations and layout 96 4 The plant communities 97 4.1 Syntaxonomic conspectus 97 4.2 The and fayal-brezal: "Monteverde" (Pruno hixae-Lauretea novocanariensis 107 4.2.1 General floristic and chorological aspects in El Hierro 109 4.2.2 The humid laurel forest (Lauro novocanariensis-Perseetum indicae, race of Pericallis murrayi) 117 4.2.2.1 Variant of Gesnouinia arborea 122 4.2.2.2 Variant of Geranium purpureum 124 4.2.3 The dry laurel forest: "Monteverde seco" (Visneo mocanerae- Arbutetum canariensis, race of Pericallis murrayi) 127 4.2.3.1 The variant of Picconia excelsa 129 4.2.3.2 The pure variant and plantation of Arbutus canariensis 134 4.2.4 The Myrica-Erica scrub: Fayal-brezal (Myrico favae-Ericetum arboreae, race of Pericallis murrayi) 134 4.2.4.1 Variant of Ilex canariensis 136 4.2.4.2 The central variant 138 4.2.4.3 Variant of Ebingeria elegans 142 4.2.5 Addendum: The bramble thickets (Rubio periclymeni-Rubetum) 147 4.2.6 The monteverde — a summary 148 4.3 The Canary pine forest: "Pinar" (Chamaecvtiso-Pinetea canariensis) 153 4.3.1 General notes 153 4.3.2 Fire and other calamities 156 4.3.3 The Canary pine forest of El Hierro (Bvstropogo ferrensis-Pinetum canariensis) 158 4.3.3.1 Community or association? - The search for character species of the Bvstropogo-Pinetum 162 4.3.3.2 The subassociation of Erica arborea (Bvstropogo ferrensis- Pinetum canariensis ericetosum arboreae) 167 4.3.3.3 The typical subassociation (Bvstropogo ferrensis-Pinetum canariensis typicum) 169 4.3.3.3.1 The pure variant 170 4.3.3.3.2 The variant of aculeatum 170 Content 5

4.3.4 The Canary pine forest - a summary 175 4.4 The thermophile scrub: "Bosque termofilo" (Rhamno crenulatae- Oleetea cerasiformis) 177 4.4.1 The dwarf scrub of the S declivities and high altitudes: "Tomillares" (Eehio aculeati-Micromerietum hyssopifoliae) 179 4.4.1.1 The subassociation of Rubia fruticosa ssp. fruticosa (Echio aculeati-Micromerietum hvssopifoliae rubietosum fruticosae subass. nova) 179 4.4.1.2 The typical subassociation (Echio aculeati-Micromerietum hvssopifoliae tvpicum) 188 4.4.2 The white broom scrub: "Retamar" (Echio hierrensis-Retametum rhodorhizoidis) 189 4.4.3 The substitutional scrub of the windward declivities (Rhamno crenulatae-Hvpericetum canariensis, altitudinal form of Erica arborea) 195 4.4.4 The thermophile scrub communities - a summary 200 4.4.5 Addendum: Transitional communities 203 4.5 The rock communities 208 4.5.1 Crassulacean communities (Greenovio-Aeonietea) 209 4.5.1.1 The Crassulacean community of the intermediate altitudes (Aeonietum longithvrsi, altitudinal form of Sonchus hierrensis) 213 4.5.1.2 The Crassulacean community of the high altitudes (Soncho- Greenovietum diplocyclae) 218 4.5.1.2.1 The subassociation of Phyllis nobla (Soncho-Greenovietum diplocvclae phyllidetosum noblae subass. nova) 224 4.5.1.2.2 The subassociation of Tuberaria guttata (Soncho-Greenovietum diplocvclae tuberarietosum guttatae subass. nova) 227 4.5.1.2.3 The subassociation tvpicum 230 4.5.1.3 The Crassulacean community of shady rocks within the monteverde (Davallio canariensis-Aichrysetum laxi) 230 4.5.1.4 The community of Aeonium spathulatum 231 4.5.2 Communities characterised by chasmophytic and epiphytic ferns 233 4.5.2.1 The community of Cheilanlhes guanchica 233 4.5.2.2 The Davallio canariensis-Polvpodietum macaronesici and related communities 238 4.5.2.3 The fern communities of wet habitats and half-caves (Adiantctea) 243 4.5.3 Communities of urban walls 244 4.5.4 The rock communities - a summary 245 4.6 Pastures and ruderal communities 248 4.6.1 Perennial pastures and ephemeral springtime communities (Poctea bulbosae and Tuberarietea guttatae) 249 6 Content

4.6.1.1 Perennial pastures in the NE highland (Trifolio subterranei-Poetum bulbosae, phase of Galactites tomentosa) 252 4.6.1.2 The Tuberario guttatae-Ophioglossetum lusitanici 256 4.6.1.3 The Hypochaerido glabrae-Tuberarietum guttatae 259 4.6.2 The perennial succession community of fallows (Pericallido murrayi-Bituminarietum bituminosae ass. nova) 263 4.6.3 The community of Raphanus raphanistrum & Bromus diandrus 273 4.6.4 The ruderal community of intermediate and low altitudes (Bromo- Hirschfeldietum incanae) 280 4.6.5 The highly nitrophilous ruderal community (Chenopodio muralis- Malvetum parviflorae) 283 4.6.6 The pastures and ruderal communities - a summary 287 4.7 Addenda 294 4.7.1 The tread community on paths and trails (Polycarpo tetraphvlli- Cotuletum australis) 294 4.7.2 Communities of moist or wet habitats and fresh water 298 4.8 Synoptical graphics and tables 303 5 Summary and prospectus 331 6 Literature 335 7 Appendix 363 7.1 Species of low constancy in the differentiated tables 363 7.2 Index of figures and tables 371 Plates 377