07-Gouvas Et Al
Total Page:16
File Type:pdf, Size:1020Kb
Journal of Biological Research-Thessaloniki 8: 177 – 187, 2007 J. Biol. Res.-Thessalon. is available online at http://www.jbr.gr Indexed in: WoS (Web of Science, ISI Thomson), CAS (Chemical Abstracts Service) and DOAJ (Directory of Open Access Journals) Life-form and chorological spectra of the vegetation units of Mount Hymettus (C Greece) MARKOS GOUVAS and KONSTANTINOS THEODOROPOULOS* Laboratory of Forest Botany-Geobotany, Faculty of Forestry and Natural Environment, Aristotle University of Thessaloniki, 541 24 Thessaloniki, Greece Received: 19 April 2007 Accepted after revision: 30 November 2007 The life-form and the chorological spectra of the vegetation units of Mt. Hymettus were inves- tigated in the present study. The spectra were produced using both the Raunkiaer’s and the Tüxen-Ellenberg’s methods. The first method was used mainly to compare our spectra with those of existing floristic studies in Greece, while the second one was used to determine the differences between the vegetation units of Mt. Hymettus. The results revealed the general climatic charac- ter of the study area and the significant variations of the spectra between the vegetation units due to their different environmental conditions (altitude, bedrock, soil, etc.). Key words: Greece, Mount Hymettus, spectra, Pinus halepensis, phrygana. INTRODUCTION the Braun-Blanquet method, investigated the vegeta- tion succession, the degree of degradation, and the Mount Hymettus is the closest mountain to the syntaxonomy of the vegetation units of Mt. Hymet- centre of Athens and is located in the Prefecture of tus. Attiki. The forest and forested areas of Mt. Hymet- The aim of the present study was to investigate tus play an important role in regulating air quality, the life-form and the chorological spectra of the ve- temperature, water runoff during the rainy season, getation units of Mt. Hymettus. and the aesthetic value of the capital’s environment. The forest also attracts the city’s inhabitants for re- MATERIALS AND METHODS creation. The countless fires, soil erosion, and pres- sures for building plots and grazing are expected to Study area become intensified in the future, if one considers the Mount Hymettus (1026 m a.s.l.) is the sixth highest fears of some scientists regarding the severe influ- mountain in the Prefecture of Attiki, after Parnitha ences of the greenhouse effect in the Mediterranean (1413 m a.s.l.), Kitheronas (1409 m a.s.l.), Gerania basin (intense drought, desertification, etc.), and the (1351 m a.s.l.), Pateras (1131 m a.s.l.) and Pendeli predicted building activities resulted from the con- (1109 m a.s.l.). It is an isolated, steep, mountainous struction of the new Athens International Airport at mass located on the eastern edge of the Attiki basin Spata. The above activities will have repercussions on with a general orientation from the north to the the natural environment of Mt. Hymettus and there south and a length of ca. 23 km. The mountain (Fig. is a danger that the mountain, together with other fo- 1) can be separated into two parts: the northern part rested areas of Attiki, will become isolated. (Megas Hymettus, according to Theofrastus), in the The most thorough botanical studies on Mt. Hy- centre of which is the highest peak (Evzonas 1026 m mettus are those by Zerlentis (1965), Margaris (1976) a.s.l.), and the southern part (named Ellaton or Any- and Gouvas (2001). Gouvas (2001) by analysing the dros Hymettus), with the peaks of Profitis Ilias (659 data of a total of 198 relevés, that were taken using m a.s.l.), Mavrovouni (770 m a.s.l.), Stroma (725 m a.s.l.), Dasomeni Koryfi (641 m a.s.l.) and Stavraetos ′ ′′ * Corresponding author: tel.: +30 2310 992765, fax: +30 (628 m a.s.l.). The study area extends from 37Æ50 11 2310 992773, e-mail: [email protected] to 38Æ00′15′′ N and from 23Æ45′31′′ to 23Æ50′48′′ E. 177 178 M. Gouvas and K. Theodoropoulos — Vegetation units of Mount Hymettus (C Greece) FIG. 1. Schematic map of Mt. Hymettus. M. Gouvas and K. Theodoropoulos — Vegetation units of Mount Hymettus (C Greece) 179 The geological formations of Mt. Hymettus be- trees of J. oxycedrus subsp. macrocarpa also grow long to the Attic-Cycladic zone, and more precisely to above Panagos up to 500 m a.s.l. Oaks growing on the Attica Unit (Mountrakis, 1985). The mountain is soils that originate from marble substrates, are ac- comprised mainly of marbles and schists (I.G.M.E., companied by Phlomis fruticosa and Euphorbia acan- 1983). The soils of Mt. Hymettus are very shallow thothamnos, while those on schists and other sub- (less than 30 cm), and bare rock and stone cover is strates are accompanied by Sarcopoterium spinosum abundant. Throughout the area, soil pH values are and Genista acanthoclada. greater than 7. Soils show intense erosion and in so- In the area south of Glyfada at altitudes up to 400 me areas, especially those close to the summits, plant m a.s.l., the oaks start to thin out until they disappear growth is limited to rock fissures (Gouvas, 2001). from some areas, whereas the taxa Pistacia lentiscus, The climate of the study area is typical Mediter- Olea europaea var. sylvestris, Calicotome villosa and ranean, with mild winters and dry hot summers (Csa Juniperus phÔenicea dominate. Within this area, Ci- according to Köppen’s classification), while on its stus parviflorus grows. This taxon prefers soils of schist highest summit the summers are classified as warm substrates, while Phlomis fruticosa and Euphorbia (Csb). Mountain slopes up to 600 m in altitude (semi- acanthothamnos prefer marble-based soils. arid bioclimatic layer) belong to the temperate semi- The agricultural areas occurring within the study arid Mediterranean climate, and those above 600 m area are restricted to the lower regions of Mt. Hymet- (cold bioclimatic layer), belong to the cool sub-humid tus close to the Mesogeion plane and comprise main- Mediterranean climate, according to Emberger’s clas- ly olive groves and vines. A small olive grove is also sification. The summer drought period is long and found in the area of the Kesariani monastery. ranges from five to seven months, according to data Finally, it should be noted that during reforesta- of the meteorological stations on the mountain (Gou- tion, apart from Pinus halepensis and P. brutia, large vas, 2001). numbers of Cupressus sempervirens and smaller num- In relation to its surface area, Mt. Hymettus has a bers of Ceratonia siliqua, Cercis siliquastrum, Medica- large variety of plant taxa that number over 600 (Zer- go arborea, Eucalyptus sp. and other taxa were also lentis, 1965). Physiognomically, its vegetation can be planted. distinguished into forests of Pinus halepensis (and P. brutia), degraded oaks (areas with Quercus coccifera), Methods phrygana, with or without sparse Q. coccifera, and agricultural areas. The P. halepensis forests have a This work uses the data of the phytosociological ta- wide range of cover and are generally found through- bles and the resulting vegetation units of Mt. Hymet- out the mountain. These forests, originated from re- tus (Tables 1, 2) (Gouvas, 2001) to produce and inter- forestation, cover all the western slopes north of the pret the life-form and the chorological spectra of the Kareas monastery and the area above Voula, and mountain. Elaboration of the spectra was performed grow mainly on schist substrates. The other P. hale- following the method used for floristic studies (Raun- pensis forests are mainly natural, while around the kiaer, 1910), as well as the Tüxen & Ellenberg (1937) monasteries of Kareas, Kesariani and Asterios, seve- method which is preferred for phytosociological stud- ral P. brutia trees have been planted. ies. In accordance with the first method, within each Oaks cover the majority of the mountain and phytosociological table, the sum of taxa of each life- comprise large or small stands of Q. coccifera, inter- form and the chorological type were calculated, fol- spersed with clearances filled with Cistus and other lowed by their percentages. phryganic taxa, and many herbaceous plants. Pistacia According to the second method, not only the terebinthus and Phillyrea latifÔlia occur occasionally, participation of every life-form or chorological type while below 600 m a.s.l. they grow along with Pistacia was used, but also the presence of the species in the lentiscus, Olea europaea var. sylvestris (often planted vegetation units (presence in the phytosociological in reforestation efforts), Erica manipuliflora, Calico- tables). The spectra were calculated using the equa- tome villosa, etc. Locally, mainly on the eastern slo- tion: percentage=(A/B)×100, where A is the num- pes, Juniperus phÔenicea occurs and in some cases its ber (indicating the presence) of each life-form or cho- cover values reach 40%. Juniperus oxycedrus subsp. rological type in the phytosociological table and B is oxycedrus is observed in a very small area, just south the total number (indicating the presence) of all taxa of the Evzonas summit at 800-850 m a.s.l. Individual in the phytosociological table. These spectra (Scamo- 180 M. Gouvas and K. Theodoropoulos — Vegetation units of Mount Hymettus (C Greece) TABLE 1. Syntaxonomic-synsystematic synopsis of the vegetation of Mt. Hymettus (Gouvas, 2001) CLASS: Cisto-Micromerietea julianae Oberd. 1954 ORDER: Sarcopoterietalia spinosi Eig 1939 ALLIANCE: Hyperico empetrifolii-Micromerion graecae Barb. et Quez. 1989 SUBALLIANCE: Phlomido fruticosae-Euphorbienion acanthothamni Barb. et Quez. 1989 ASSOCIATION: Dorycnio hirsuti-Micromerietum graecae Barb. et Quez. 1989 VARIATION: var. from Sedum acre VARIATION: var. from Ptilostemon chamaepeuce VARIATION: var. from Ononis pusilla VARIATION: var. from Globularia alypum VARIATION: var. from Thesium humile VARIATION: var. from Hirshfeldia incana SUBALLIANCE: Hyperico-Micromerienion Barb. et Quez. 1989 ASSOCIATION: Origano vulgare-Ericetum arboreae Barb.