Long-term persistence of steppe vegetation in the highlands of Arasbaran protected area, northwestern Iran, as inferred from a pollen record

Palynological analysis and radiocarbon dating of a short sediment core from a high-altitude mire in the Arasbaran area of northwestern Iran reveals long-term vegetation dynamics, climate change and anthropogenic impact. Our findings indicate the prevalence of semi-desert steppe vegetation, with a variety of Asteraceae - mainly Lactuceae - species from 3000 to 1440 cal yr BP. This period is followed by a higher occurrence of Artemisia spp. and Brassicaceae (1440-1330 cal yr BP), a re-expansion of Lactuceae (1330-1030 cal yr BP) and Brassicaceae (1030-330 cal yr BP) and, finally, Caryophyllaceae species (since 330 cal yr BP). The reconstructed millennia-long dry climate in the highlands of northwestern Iran is in good accordance with climate reconstructions from other east Mediterranean sites. Two phases of moister conditions between 2100-1400 and 1000-350 cal yr BP would correspond to altitudinal Quercus-Carpinus forest expansion in the Arasbaran area. The earliest indication of anthropogenic activity in the area dates back to the onset of the record, around 3000 cal yr BP. The occurrence of small maxima of Juglans regia, Corylus avellana and Cornus mas pollen at around 1350 cal yr BP is interpreted to reflect a temporary expansion of fruit cultivation. For the last millennium the occurrence of pollen attributable to Polygonum, Euphorbia, Plantago and Rumex suggests a diversification of steppe vegetation, which may reflect intensified agropastoral activities in the Arasbaran highlands. Based on our pollen record, the regional vegetation in the Kalan area remained largely stable over the last three millennia. However, changes in local hydrology caused substantial changes in wetland vegetation

A Green's function approach to transmission of massless Dirac fermions in graphene through an array of random scatterers

We consider the transmission of massless Dirac fermions through an array of short range scatterers which are modeled as randomly positioned $\delta$- function like potentials along the x-axis. We particularly discuss the interplay between disorder-induced localization that is the hallmark of a non-relativistic system and two important properties of such massless Dirac fermions, namely, complete transmission at normal incidence and periodic dependence of transmission coefficient on the strength of the barrier that leads to a periodic resonant transmission. This leads to two different types of conductance behavior as a function of the system size at the resonant and the off-resonance strengths of the delta function potential. We explain this behavior of the conductance in terms of the transmission through a pair of such barriers using a Green's function based approach. The method helps to understand such disordered transport in terms of well known optical phenomena such as Fabry Perot resonances.Comment: 22 double spaced single column pages. 15 .eps figure

Wild grapevine (Vitis vinifera subsp. sylvestris) in the Hyrcanian relict forests of northern Iran: an overview of current taxonomy, ecology and palaeorecords

International audienc

Four millennia of vegetation and environmental history above the Hyrcanian forest, northern Iran

Past vegetation, fire, and climate dynamics, as well as human impact, have been reconstructed for the first time in the highlands of the Gilan province in the Alborz mountains (above the Hyrcanian forest) for the last 4,300 cal yrs BP. Multi-proxy analysis, including pollen, spores, non-pollen palynomorphs, charcoal, and geochemical analysis, has been applied to investigate the environmental changes at 2,280 m a.s.l., above the Hyrcanian forest. Dominant steppe vegetation occurred in the study area throughout the recorded period. The formation of the studied mire deposits, as well as vegetation composition, suggest a change to wetter climatic conditions after 4,300 until 1,700 cal yrs BP. Fires were frequent, which may imply long-lasting anthropogenic activities in the area. Less vegetation cover with a marked decrease of the Moisture Index (MI) suggests drier conditions between 1,700 and 1,000 cal yrs BP. A high proportion of Cichorioideae and Amaranthaceae, as well as the reduction of trees, in particular Fagus and Quercus, at lower elevations, indicate human activities such as intense livestock grazing and deforestation. Soil erosion as the result of less vegetation due to dry conditions and/or human activities can be reconstructed from a marked increase of Glomus spores and high values of K and Ti. Since 1,000 cal yrs BP, the increasing MI, as well as the rise of Poaceae and Cyperaceae together with forest recovery, suggest a change to wetter conditions. The occurrence of still frequent Cichorioideae and Plantago lanceolata along with Sordaria reflect continued intense grazing of livestock by humans

Palynological analysis of the Late-Holocene vegetation and climate of Ganli-Gol wetland near Urmia, northwestern Iran

Palynologial analysis of a core from Ganli-Gol wetland reveals the Late-Holocene vegetation dynamics and the role of climate and man on the past environment in northwestern Iran. Our pollen diagram shows substantial changes in vegetation over the period 3000-1600cal.BP. Artemisia and/or Chenopodiaceae must have abundantly contributed in the vegetation composition of the area. Poaceae and Cyperaceae were important wetland vegetation as the high values of their pollen suggest. The low values of arboreal pollen throughout the record indicate the negligible contribution of forest vegetation over the whole period. We used C/A (Chenopodiaceae/Artemisia) pollen ratio, to estimate the past dry/wet periods in the area. During 3000-2850cal.BP, a relatively dry climate and the expansion of steppe vegetation can be inferred from low values of C/A. Increased values of Artemisia with the occurrence of oak during 2850-2652cal.BP may reflect less drier condition with semi-steppe vegetation. The end of this period is marked by low values of Quercus and Artemisia and high Chenopodiaceae, suggesting the prevalence of a cold and dry condition with steppe-desert vegetation. Increased values of Quercus combined with high values of Artemisia and Poaceae could be taken as indications for improved climatic condition during 2338-2020cal.BP. The occurrence of Vitis and relatively high values of anthropogenic pollen types, e.g. Plantago lanceolata and Centaurea solstitialis, are evidences for increased agricultural activity in this period. The period 2020-1614cal.BP is marked by low values of Quercus and Artemisia and high Chenopodiaceae pollen suggesting that steppe vegetation and a relatively arid condition prevailed in the area

Quantitative and qualitative characteristics and altitudinal zonation of Arasbaran forest protected area, northwestern Iran

Knowledge on silvicultural characteristics of forest stands is prior to any forest management practice. The objectives of this study were to determine the forest types and to explore some quantitative and qualitative characteristics of Arasbaran forest protected area along an altitudinal gradient. Therefore, circular plots of 400 m2 at 50-meter elevation intervals were established along five altitudinal transects, 100 meters apart, from the lowest (1100 m a.s.l) to the highest (1725 m a.s.l) forest limit. In each plot, the physiographic conditions including slope gradient, altitude and geographic coordinates were determined. Woody species were identified and the diameter at breast height (dbh) of all trees above 7.5 cm dbh, as well as origin, health status, number of stems and tree leaning were measured. In addition, the regeneration frequency of each individual tree taller than 1.30 m in three diameter classes (0-2.5, 2.5-5 and 5-7.5 cm dbh) and shorter than 1.3 m in three height classes (0-10, 10-50 and 50-130 cm) were examined within 100 m2 regeneration plots. Four forest types including Carpinus betulus - Quercus petraea (1100-1400 m a.s.l), C. betulus - Q. petraea - Acer campestre- Fraxinus excelsior (1400-1500 m a.s.l), C. betulus - Q. petraea - A. campestre (1500-1650 m a.s.l) and C. betulus - Q. macranthera (1650-1725 m a.s.l) were distinguished along the altitudinal gradient. The highest number of stems per ha (mature and regeneration stands) and average basal area were observed in C. betulus - Q. macranthera type, whereas the highest average dbh was recorded in C. betulus - Q. petraea forest type. Finally, seed regeneration was most common in C. betulus - Q. petraea - A. campestre forest type

Survey on biology of Tortrix viridana L. in laboratory and field conditions and its distribution in West-Azerbaijan

Tortrix viridana L. is the most important pest of oak trees in Iran. The larvae of the pest impose high economic damages because of feeding on the leaves and buds of oak trees and leaving heavy destructions on the invaded trees. To determine the biological characteristics and also the rate of the infestation with this pest, random sampling was performed from 30 trees of Quercus infectoria, Q. libani and Q. brantii and four branches from 4 cardinal sides, each of 50 cm length were cut off as units for the enumeration of green oak moth larvae (or pupa) and after counting the larvae, were transferred to the laboratory. Larvae of the last instars are separated based on their host oak species and were reared till their entrance to pupa stage. The weigh of 4 day old female pupae was measured with a digital balance. Results showed neonate larvae of T. viridana in Mirabad and Pardanan enter oak buds after being hatched in 25th Februray and 10th March, respectively. Larvae enter 2'd instar after eating the internal contents of oak buds, then the third and 4th instar larvae consume whole buds and even oak leaves and after development to the 5th larval instar and roll the leaves and enter pupal stage in Mirabad and Pardanan regions. The occurrence of the peak of adult insects in Mirabad and Pardanan was recorded in 20th May and 7th June, respectively. Adult activities take two months. The pupa which is formed on Q. infectoria was the heaviest. Attacked trees from early May onwards revitalization and create a new leaf. New leaves, pale green and are smaller than normal leaves. Unfortunately, in this situation local people to imagine of wizened of damaged trees, they proceeded to cut them

The Late-Holocene climate change, vegetation dynamics, lake-level changes and anthropogenic impacts in the Lake Urmia region, NW Iran

International audienceTwo short (100 and 175 cm-long) sediment cores from the southwestern corner of Lake Urmia provide a record of vegetation dynamics, lake-level changes and the role of climate and humans in shaping the landscape around Lake Urmia over the last 2550 years. Relatively low values of arboreal pollen (AP), and substantial values of Artemisia pollen from 2550 to 1500 cal BP indicate the prevalence of steppe vegetation and relatively arid climate in the area. However, a prominent peak of Riella spores may indicate a short-lived lake-level rise for the period 1900-2000 cal BP. The next period, 1500-550 cal BP, is characterized by substantial rise in AP, particularly Quercus, and a sharp decline of Artemisia, Chenopodiaceae/Amaranthaceae and wetland pollen types, suggesting the expansion of oak forests under a rather moist climate and/or a decline in agro-sylvo-pastoral practices in the area. Agricultural activity in the area can be inferred from sporadic occurrences of Vitis, Ricinus and Juglans pollen from the beginning of the record. The rise of saline habitat pollen types between 1100 and 800 cal BP, along with increased values of magnetic susceptibility and organic matter, suggest a lower water level and the subaerial exposure of saline mud flats, which could favour the re-colonization of chenopods and other halophytes around the margins of the lake. Thus, the Medieval Climatic Anomaly seems to be warmer-than-present in the Lake Urmia region. From 450 to 150 cal BP, the decline in Quercus and high values of Artemisia, along with higher lake levels and high magnetic susceptibility values, could be associated with the Little Ice Age. Since 500 cal BP, Quercus and Riella steadily decline and fade out towards the surface of the core, whereas pollen types attributable to steppe and desert vegetation increase. A prominent increase in organic matter in the uppermost part of the record could be associated with a lower lake level and the expansion of wetland vegetation in the recent past. Our findings suggest that the regional forest coverage in the highlands of Zagros and Azerbaijan has reached its minimum during recent decades, while Urmia's lake level dropped dramatically (increasing its water salinity) most likely as a function of extensive anthropogenic activities and general climate aridification. (C) 2015 Elsevier Ltd and INQUA. All rights reserved

Notes on Arboricultural and Agricultural Practices in Ancient Iran based on New Pollen Evidence

New pollen evidence from two sites in South-Central Zagros (Lake Maharlou), Southwestern Iran, and Sahand Mountains (Lake Almalou), Northwestern Iran, provide evidence for the emergence of tree cultivation in Southwestern Iran since the 3rd and 2nd millennia BC and upland agricultural activities in Northwestern Iran since 5th to 3rd centuries BC. Juglans cf. regia could have been cultivated firstly at ~ 2500 BC and became more extensively cultivated since ~ 1200 BC. Platanus cf. orientalis was also probably cultivated very early at ~ 1900 BC during the Middle Elamite period (2800-550 BC) and became more widely cultivated from ~ 1200 BC along with Juglans. The latter arboricultural events could have resulted from the establishment of great urban civilizations in Southwestern Iran. The rise of the Persian Empires seems to have been associated with a large-scale agricultural revolution over the Iranian Plateau. During the Persian Achaemenid Empire (550-330 BC) tree cultivation expanded in the Lake Maharlou area and agricultural practices expanded into upland areas in Lake Almalou area probably due to socio-economic stability and the development of water exploitation and irrigation techniques. The Parthian (250 BC-225 AD) and Sassanian (224-642 AD) periods were also associated with tree cultivation practices in Lake Maharlou area but to a lower extent comparing to the Achaemenid period. In the Lake Almalou area, the Parthian period saw no spectacular agricultural event at least partly due to political and socio-economic instability caused by conflicts with Romans over Armenia. The socio-economic stability and further development in agricultural techniques during the Sassanian Empire could, however, favor again the large-scale tree cultivation practices in Northwestern Iran. The Post-Islamic period is characterized by reduced agricultural activities in the Iranian Plateau most probably due to political instability caused by numerous invasions by Arabs, Turks and Mongols. The last signifi cant agricultural event recorded in the Lake Almalou pollen record is the appearance of Ricinus communis cultivated since the beginning of the Safavid Empire (1501-1722 AD).De nouvelles données polliniques provenant de deux sites dans les montagnes du Zagros (lac Maharlou, Sud-Ouest l’Iran) et de Sahand (lac Almalou, Nord-Ouest de l’Iran), apportent des indications sur l’émergence de l’arboriculture dans le Sud-Ouest iranien depuis les IIIe et IIe millénaires av. J.-C., et sur les pratiques agricoles dans les hautes terres du Nord-Ouest iranien du Ve au IIIe siècles av. J.-C. Juglans cf. regia fut probablement cultivé dès 2500 av. J.-C., puis plus extensivement à partir de 1200 av. J.-C. environ. Platanus cf. orientalis fut probablement cultivé précocement, vers 1900 av. J.-C., au cours de la période élamite moyenne (2800-550 av. J.-C.), et il devint plus largement cultivé à partir de ca. 1200 av. J.-C, parallèlement à la culture de Juglans. Ces innovations agricoles ont pu résulter du développement des grandes civilisations urbaines dans le Sud-Ouest de l’Iran. L’émergence de l’Empire perse semble être associée à une révolution agraire à grande échelle sur le plateau iranien. Sous l’Empire achéménide (550-330 av. J.-C), l’arboriculture s’est développée dans la région du lac Maharlou alors que l’agriculture atteignait les hautes terres autour du lac Almalou, probablement en raison d’une plus grande stabilité socio-économique et du développement des techniques d’irrigation. Les périodes parthe et sassanide (224-642 de notre ère) ont également vu le développement de l’arboriculture dans la région du lac Maharlou, mais dans une moindre mesure que lors de la période achéménide. Dans la région du lac Almalou, la période parthe ne témoigne pas de pratiques agricoles spectaculaires, en raison peut-être de l’instabilité politique et socio-économique consécutive aux conflits avec l’Empire romain en Arménie. Sous l’Empire sassanide, la stabilité socio-économique et le renouveau des techniques agricoles ont pu toutefois favoriser le développement à grande échelle de l’arboriculture dans le Nord-Ouest de l’Iran. La période qui suit l’arrivée de l’Islam est caractérisée par des activités agricoles moins importantes sur le plateau iranien, très probablement en raison de l’instabilité politique liée aux invasions arabes, turques et mongoles. Le dernier fait agricole significatif enregistré au lac Almalou est l’apparition de Ricinus communis, cultivé dès le début de l’Empire safavide (1501-1722 de notre ère).Djamali Morteza, Miller Naomi F., Ramezani Elias, Andrieu-Ponel Valérie, de Beaulieu Jacques-Louis, Berberian Manuel, Guibal Frédéric, Lahijani Hamid, Lak Razieh, Ponel Philippe. Notes on Arboricultural and Agricultural Practices in Ancient Iran based on New Pollen Evidence. In: Paléorient, 2010, vol. 36, n°2. pp. 175-188