Historical Background of the Trust
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Transylv. Rev. Syst. Ecol. Res. 2, (2005), "The Târnava River Basin" 99 AN ECOLOGICAL SURVEY OF THE CERAMBYCIDAE (COLEOPTERA) IN THE GEOGRAPHIC BASIN OF THE TÂRNAVA MICĂ VALLEY (TRANSYLVANIA, ROMANIA) Petru ISTRATE * * “Bolyai Farkas” Theoretical Secondary School, 3 Bolyai Street, Târgu Mureş, Mureş County, Romania, RO - 540064, [email protected] KEYWORDS: cerambycids-vegetation relations, Transylvania, Romania. ABSTRACT We have investigated the Cerambycidae within five areas of the Târnave Rivers Plateau and the Gurghiu Mountains. A connection has been emphasized between the calendar periods of adult emergence and the spaced out blooming of various ligneous (woody) plants. Various floral merocenoses are presented which include the participation of the anthophilous/palynophagous Cerambycidae. The negative impact of man on the ecosystems (particularly on the forest ecosystem) is stressed, which results in a decrease in the number of Longhorned Beetle/Cerambyx species. The Târnava Mică River basin is still a geographical area rich in coleopterological (beetle) fauna, yet with patchy distribution. For four years we have collected here specimens belonging to 63 Cerambycidae species and we have managed to determine 60 of them. RÉSUMÉ: Étude écologique concernant les Cerambycidae du basin géographique de la rivière Târnava Mică. Renseignements concernant la répartition des Cerambycidae dans cinq zones du Plateau des (rivières de) Târnava et des Montagnes de Gurghiu, étudiées par nous. On a mis en évidence une liaison entre les saisons d’émergence des adultes et la floraison échelonnée des diverses plantes ligneuses. On présente plusieurs mérocénoses florales qui impliquent la participation des Cerambycidae anthophiles/palynophages. On souligne l’impacte négatif que l’homme produit sur les écosystèmes, surtout sur l’écosystème forestier, qui conduit à une diminution du nombre d’espèces de capricorne/cérambyx. Le bassin de la rivière Târnava Mică représente encore une région géographique avec une faune qui abonde en coléoptères, mais qui sont dispersés de manière inégale - dont on a collecté, pendant 4 ans, des spécimens (exemplaires) appartenant à 63 espèces de Cerambycidae et dont on a déterminé 60 espèces. REZUMAT: Studiu ecologic asupra cerambicidaelor în bazinul geografic a râului Târnava Mică. Au fost studiate Cerambycidaele din cinci arii ale Platoului Târnava şi Munţilor Gurghiu. A fost reliefată o conexiune între perioadele calendaristice a emergenţei adulţilor şi înflorirea a variate plante lignofile. Variate merocenoze florale sunt prezentate care includ participarea Cerambycidaelor. Impactul negativ al omului asupra ecosistemelor (în mod particular în ecosistemele forestiere) este accentuat, fapt care induce descreşterea numărului de specii de Cerambicidae. Bazinul râului Târnava Mică este încă, o arie geografică bogată în faună coleopterologică, deşi cu o distribuţie neuniformă. Pentru o perioadă de patru ani am colectat aici indivizi aparţinând la 63 de specii de Cerambycidae şi am reuşit determinarea a 60 dintre ele. 100 P. Istrate – An ecological survey of theCerambycidae in the Târnava Mică Valley (99 ~ 108) INTRODUCTION A description of the geographical region of the Târnava Mică Valley. The Târnava Mică Valley has resulted from the river and its tributaries eroding the marl, clay and also the sandstone layers of the Târnava Plateau. The bells, which are typical with the relief here look like overhanging bridges running along the right side of the river and its affluents. The hill slopes look more or less steep. The topoclimates determined by the irregular relief favour such grassy vegetation, that one can find nowhere else in the country an equally diverse range of species. The highly eroded, steep, southern slopes shelter various xerophytic species, such as Adonis vernalis, Pulsatilla montana, Stipa sp., Iris pumilla, Iris aphylla, Iris variegata, Crambe tatarica, Festuca sp., Dictamnus albus, Carex humilis - particularly in the lower area, where the topoclimatic conditions are similar to those in the Transylvanian Plain and the Secaş Plateau. The terraces on the left side of the Târnava Mică River are cultivated, but many lands there are also lie fallow. The tops of the local hills and the northern slopes are patchily covered with woods, which consist, towards the west of the studied river, mainly of Quercus robur, Quercus petraea and Carpinus betulus, associated with some thermophilic species. These patchy forests are quite sparse and clear, the soil is covered with thick grass and many underbrush species grow inside and on the edge of the forest. Larger forests spread out eastward and they even cover some of the southern hill slopes. Beech forests can be found in the Sovata region, whereas pine spruce and fir-trees are present in the mountains areas, along the Târnava Mică River tributaries. The anthropic changes of the ecosystems, particularly those undergone by the forests fundamentally altered their structures, lime and hornbeam trees replace the compact oak-tree clumps, which are sparse here. Old trees showing signs of drying up have been constantly felled and the alluvial plain forests have been cut down, so that most of the forests in the west part of the Târnava Plateau are of secondary types and mainly consist of young shrubs and bushes of the same age, a fact which obviously explain the scarce presence of the Coleoptera species in this area. The state of current research on Cerambycidae in Romania The Cerambycidae, or the wood beetles, belong to the Coleoptera, rich in species (about 20000 all over the world), most of them spread in the Neotropical and Oriental regions. We can also find here the largest-sized insects belonging to the Titanus genus - more than 150 mm large, as well as glaring, light-coloured species. About 240 species have been found in Romania. An important contribution in studying the Coleoptera on the Romanian territory have been done: Bielz (1850, 1852, 1853, 1887), Siedlitz (1891), Petri (1912), Csiki (1895), Worel (1951) - concerning the Cerambycidae group in Transylvania. Researchers like Hormuzachi (1902, 1904), Montandon (1906), Ieniştea (1932), Panin (1941), Săvulescu (1969, 1972), Serafim (1985, 1997, 1998), Ruicănescu (1992, 1997) have collected a rich material in Romania, establishing extensive fauna lists, which include the Cerambycidae species, too. The biological material concerning the Cerambycidae group species is found in the collections of the Natural History Museum in Sibiu, the Agronomy Faculty in Timişoara, the Forestry Institute in Braşov, the „Grigore Antipa” National Natural History Museum in Bucharest, the Museum of Natural Science in Târgu - Mureş, as well as in other museums and private collections. Transylv. Rev. Syst. Ecol. Res. 2, (2005), "The Târnava River Basin" 101 The Cerambycidae fauna in Romania is relatively well known due to these collections and to the fauna lists that have been published. Although relatively old, “Coleoptera - Cerambycidae” in the Fauna of the People’s Republic of Romania, 10-5 (1961) is still the most complex study published in Romania so far. No Romanian researcher has ever thoroughly studied the Cerambycidae, although these can cause great damage to the woods by ruining the trees (all the Cerambycidae species are phytophagous and their larvae feed on the cellulose of the host plant, boring galleries into the tree wood). Fortunately, the Cerambycidae species nowadays attack the trees sporadically, mostly in the vast mountain woods; the other forests covering smaller areas can be easily kept under control within the forestry systems. Furthermore, insecticides which are regularly sprayed over from the planes destroy the worms, the Ipidae etc., which usually cause the trees to grow weaker, thus favouring the attack and the development of the Cerambycidae in the forests. Basically, over the last 60 - 70 years there has been a gradual decrease in the number of Cerambycidae species in Romania - which were formerly considered harmful, are pretty scarce nowadays in most of the regions. MATERIALS AND METHODS The Cerambycidae were collected manually or by shaking the studied trees or underbrush flowers on the edge of the forests, into entomological umbrellas, in the period of time between 1988 and 2002. An entomological net was used when mowing the grass in the forest glades, or the blooming herbs in the meadows or on the edge of the forests - given the fact that the larvae of these insects are xylophagous and their adults usually live near the forests, too. The steppe Cerambycidae species, such as the ones in the Dorcadion and Neodorcadion genus, were collected from the glades and meadows, from the edge of the forests, or from the local country roads - in spring and also in early summer. Many Cerambycidae feeding on the tree leakage, or which do not leave the tree trunks they emerged from, while breeding, were collected after attentively examining the age-old oak-trees which showed signs of attack, i.e. galleries for insect emergence, sap leakage, brownish spots, dry twigs and branches. The branches and the trunks of the trees fallen on the edge of the forest were examined, as well as the dry poplars, the dry faggots lying along the forest roads and the wood piles left after clearing certain sectors of the forest. Several species that live in the trees bark have been collected from the trunks of live trees which were growing inside the forest. The areas around the electric bulbs in the isolated countryside railway stations were also investigated and some of the Cerambycidae species were collected after the identification and inspection of the host herbs, such as Matricaria sp., and Artemisia sp. The best results were obtained in the case of the diurnal Cerambycidae species after 10 o’clock in the morning as the sun raises higher. The nocturnal and the sunset species were examined after 18.00 hours and the best results were obtained in the case of Cerambyx cerdo species around 21.00 - 22.00 hours. Special attention was given to isolated areas, less influenced by man, such as the old-age brushes and the sunny forest edges, given the fact that all the species are thermophilic and mesophilic and get warmed up in the sun in the daytime.