Long-term vegetation dynamics along altitudinal and longitudinal gradients in the Hyrcanian forest region  (northern Iran)

Homami Totmaj, Leila

The role of climate, fire and anthropogenic impacts during the late Quaternary

dc.contributor.advisor	Behling, Hermann Prof. Dr.
dc.contributor.author	Homami Totmaj, Leila
dc.date.accessioned	2022-12-14T17:04:03Z
dc.date.available	2022-12-16T00:50:11Z
dc.date.issued	2022-12-14
dc.identifier.uri	http://resolver.sub.uni-goettingen.de/purl?ediss-11858/14415
dc.identifier.uri	http://dx.doi.org/10.53846/goediss-9622
dc.format.extent	146 Seiten	de
dc.language.iso	eng	de
dc.subject.ddc	570	de
dc.title	Long-term vegetation dynamics along altitudinal and longitudinal gradients in the Hyrcanian forest region (northern Iran)	de
dc.title.alternative	The role of climate, fire and anthropogenic impacts during the late Quaternary	de
dc.type	doctoralThesis	de
dc.contributor.referee	Bergmeier, Erwin Prof. Dr.
dc.date.examination	2021-12-16	de
dc.description.abstracteng	As an Arcto-Tertiary species refugium, the Hyrcanian forest region of Iran, may play an important role in investigating paleoclimatic and palaeoecological changes. This narrow belt, located between the biggest lake of the world, the Caspian Sea, and the northern slopes of the Alborz Mountains, has distinctive biodiversity compared to other geographical parts of Iran. Although the uniqueness and importance of this region are not hidden to anyone, this region was not sufficiently investigated. Hopefully, paleoclimatologists and paleobotanists have increased their investigations on this area since the last decade while focusing more on the eastern and central parts. The Gilan province, the western part of the Hyrcanian region, is the least studied province, while is of high importance due to: i) the extensive forests and wetlands which make an appropriate area to carry out palaeoecological studies ii) the importance of its vegetation history that can provide new insights into the refugium hypothesis for the west Eurasian temperate deciduous forest as is the corridor that connects the isolated southern coast of the Caspian Sea to western Eurasia iii) being the wettest among the Hyrcanian provinces, and its palaeoecology allows the comparison on an east-western precipitation gradient during the past iv) having the largest remnant of the coastal fluvial forest v) being home of the most ancient known human settlements in Iran This multi-proxy paleoenvironmental research was carried out on three different areas from mid-elevated to high elevated areas of the Gilan province. Besides, paleoenvironmental studies of the modern vegetation in two different altitudinal gradients were investigated, utilizing palynology and DNA metabarcoding approaches. The first record named Pounel (PNL) was retrieved from a mire in the highlands of the Gilan province (2280 m a.s.l.) located above the Hyrcanian forest. This study, which provides the oldest record from Gilan province, dates back to 4300 cal yr BP. The study represented the dominance of the steppe vegetation around the study area throughout the recorded period. Also, indicated wet climatic conditions between 4300 to 1700 cal yr BP. After 1700 cal yr BP until 1000 cal yr BP, vegetation cover was reduced with increased Cichorioideae and Amaranthaceae while trees decreased significantly at lower elevations. Together with increased values of K and Ti, drier conditions and/or increment of the anthropogenic activities are suggested. Since the last 1000 years, the higher frequency of Poaceae and Cyperaceae as well as the recovery of forest suggested wetter conditions. However, the still frequent Cichorioideae and Plantago lanceolata along with Sordaria may reflect continued intense livestock grazing at this study area. The second record investigated the Kholash-Kouh lake (KHL), located above the forest line (at 2000 m a.s.l.), reconstructed the vegetation, climate changes, local fire history, and anthropogenic role activities for the past 1245 cal yr BP. Based on the palynological reconstruction, the lake's surrounding (between ca. 1245-1030 cal yr BP) was covered mostly by Poaceae, Artemisia, and Amaranthaceae, indicative of open vegetation. The strong environmental disturbance is reflected by the high representation of human indicators and coprophilous spores. The high amount of macro-charcoal particles suggests widespread fire, resulting in a low proportion of arboreal vegetation. The dominance of the forest vegetation and the warmest condition are the most important characteristics of the period between 1030-730 cal yr BP. Lastly, between ca. 730-50 cal yr BP, arboreal vegetation replaced by herbs and evidenced the more open vegetation that may correlate with the Little Ice Age's cold and dry condition and/or the increased anthropogenic activities which occurred precisely during that period. The third record, as the first report from the western mid-elevated area, applied multi-proxy studies to reconstruct environmental changes, represents a high-resolution study of Annal Lake (ANL) for the late Holocene period. The lake located at 700 m elevation in the Hyrcanian forest of the Gilan province recovered the last 1690 years ago. Based on the multi-proxy analysis, a mixed forest with Alnus, Carpinus, Quercus, and Fagus were present, as well as patches of grassland areas around the lake between ca. 1690-1450 cal yr BP. At ca. 1450 cal yr BP, the forest expanded and reduced the open grassland areas until 65 cal yr BP. Different proxies indicated that humans were present in the studied area since the beginning of the recorded period. However, since 65 cal yr BP, human impact increased markedly by deforestation and cattle grazing, and settlers probably changed from pastoralism to more farmers. Ratios of geochemical elements such as V/Cr, K/Al, Rb/Al, Si/Fe, and Ca/K suggested the warmest period with more rainfall and detrital inputs forming a shallow lake between ca. 1690 – 580 cal yr BP. In contrast, warm and wet conditions changed to cold and dry conditions after around 580 cal yr BP and remained prevailed until 250 cal yr BP. Finally, due to the XRF results, the last ca. 250 cal yr BP at ANL surroundings, was experienced the wettest and relatively stable climatic conditions. The fourth and the last study investigated the modern pollen rain and forest inventory through altitudinal gradients in two different transects, from lowlands up to the slopes of the Alborz Mountains in Gilan province for the first time. The new method of DNA metabarcoding complemented the modern pollen rain data hired to investigate the representation of the vegetation along the two altitudinal transects. The capability of the DNA metabarcoding for vegetation survey was examined in this study, which emphasizes using a combination of the multi-locus approach of ITS2 and rbcL. Comparing the DNA base and pollen analytical results on the vegetation abundances around the collected samples indicated that a higher proportion of microscopy results was affected by the wind-pollinated families (such as Betulaceae and Fagaceae) due to their higher pollen production. While the results derived from DNA barcoding were more relevant to the actual vegetation cover.	de
dc.contributor.coReferee	Giesecke, Thomas Dr.
dc.subject.eng	Palynology	de
dc.subject.eng	Vegetation reconstruction	de
dc.subject.eng	Palaeoecology	de
dc.identifier.urn	urn:nbn:de:gbv:7-ediss-14415-2
dc.affiliation.institute	Biologische Fakultät für Biologie und Psychologie	de
dc.subject.gokfull	Biologie (PPN619462639)	de
dc.description.embargoed	2022-12-16	de
dc.identifier.ppn	1827070773
dc.identifier.orcid	https://orcid.org/0000-0003-4852-9811	de
dc.notes.confirmationsent	Confirmation sent 2022-12-15T06:15:01	de

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Das Dokument erscheint in:

CBL - Zentrum für Biodiversität und Nachhaltige Landnutzung (ehem. GZBÖ) [100]
CBL - Centre of Biodiversity and sustainable Land Use

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