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Gerrit Lohmann - One of the best experts on this subject based on the ideXlab platform.
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this article has been retracted what caused the mid holocene Forest Decline on the eastern tibet qinghai plateau
Global Ecology and Biogeography, 2010Co-Authors: Ulrike Herzschuh, Xingqi Liu, Claudia Kubatzki, John H B Birks, Gerrit LohmannAbstract:Aim Atmospheric CO2 concentrations depend, in part, on the amount of biomass locked up in terrestrial vegetation. Information on the causes of a broad-scale vegetation transition and associated loss of biomass is thus of critical interest for understanding global palaeoclimatic changes. Pollen records from the north-eastern Tibet-Qinghai Plateau reveal a dramatic and extensive Forest Decline beginning c. 6000 cal. yr bp. The aim of this study is to elucidate the causes of this regional-scale change from high-biomass Forest to low-biomass steppe on the Tibet-Qinghai Plateau during the second half of the Holocene. Location Our study focuses on the north-eastern Tibet-Qinghai Plateau. Stratigraphical data used are from Qinghai Lake (3200 m a.s.l., 36°32′–37°15′ N, 99°36′–100°47′ E). Methods We apply a modern pollen-precipitation transfer function from the eastern and north-eastern Tibet-Qinghai Plateau to fossil pollen spectra from Qinghai Lake to reconstruct annual precipitation changes during the Holocene. The reconstructions are compared to a stable oxygen-isotope record from the same sediment core and to results from two transient climate model simulations. Results The pollen-based precipitation reconstruction covering the Holocene parallels moisture changes inferred from the stable oxygen-isotope record. Furthermore, these results are in close agreement with simulated model-based past annual precipitation changes. Main conclusions In the light of these data and the model results, we conclude that it is not necessary to attribute the broad-scale Forest Decline to human activity. Climate change as a result of changes in the intensity of the East Asian Summer Monsoon in the mid-Holocene is the most parsimonious explanation for the widespread Forest Decline on the Tibet-Qinghai Plateau. Moreover, climate feedback from a reduced Forest cover accentuates increasingly drier conditions in the area, indicating complex vegetation–climate interactions during this major ecological change.
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Retracted: What caused the mid-Holocene Forest Decline on the eastern Tibet-Qinghai Plateau?
2010Co-Authors: Ulrike Herzschuh, H. John B. Birks, Xingqi Liu, Claudia Kubatzki, Gerrit LohmannAbstract:Aim: Atmospheric CO2 concentrations depend, in part, on the amount of biomass locked up in terrestrial vegetation. Information on the causes of a broad-scale vegetation transition and associated loss of biomass is thus of critical interest for understanding global palaeoclimatic changes. Pollen records from the north-eastern Tibet-Qinghai Plateau reveal a dramatic and extensive Forest Decline beginning c. 6000 cal. yr bp. The aim of this study is to elucidate the causes of this regional-scale change from high-biomass Forest to low-biomass steppe on the Tibet-Qinghai Plateau during the second half of the Holocene. Location: Our study focuses on the north-eastern Tibet-Qinghai Plateau. Stratigraphical data used are from Qinghai Lake (3200 m a.s.l., 36 degrees 32'-37 degrees 15' N, 99 degrees 36'-100 degrees 47' E). Methods: We apply a modern pollen-precipitation transfer function from the eastern and north-eastern Tibet-Qinghai Plateau to fossil pollen spectra from Qinghai Lake to reconstruct annual precipitation changes during the Holocene. The reconstructions are compared to a stable oxygen-isotope record from the same sediment core and to results from two transient climate model simulations. Results: The pollen-based precipitation reconstruction covering the Holocene parallels moisture changes inferred from the stable oxygen-isotope record. Furthermore, these results are in close agreement with simulated model-based past annual precipitation changes. Main conclusions: In the light of these data and the model results, we conclude that it is not necessary to attribute the broad-scale Forest Decline to human activity. Climate change as a result of changes in the intensity of the East Asian Summer Monsoon in the mid-Holocene is the most parsimonious explanation for the widespread Forest Decline on the Tibet-Qinghai Plateau. Moreover, climate feedback from a reduced Forest cover accentuates increasingly drier conditions in the area, indicating complex vegetation-climate interactions during this major ecological change.
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What caused the mid-Holocene Forest Decline on the eastern Tibet-Qinghai Plateau?
Global Ecology and Biogeography, 2009Co-Authors: Ulrike Herzschuh, H. John B. Birks, Xingqi Liu, Claudia Kubatzki, Gerrit LohmannAbstract:Aim Atmospheric CO 2 concentrations depend, in part, on the amount of biomass locked up in terrestrial vegetation. Information on the causes of a broad-scale vegetation transition and associated loss of biomass is thus of critical interest for understanding global palaeoclimatic changes. Pollen records from the north-eastern Tibet-Qinghai Plateau reveal a dramatic and extensive Forest Decline beginning c. 6000 cal. yr BP. The aim of this study is to elucidate the causes of this regional-scale change from high-biomass Forest to low-biomass steppe on the Tibet-Qinghai Plateau during the second half of the Holocene. Location Our study focuses on the north-eastern Tibet-Qinghai Plateau. Stratigraphical data used are from Qinghai Lake (3200 m a.s.l., 36°32'-37°15' N, 99°36'-100°47' E). Methods We apply a modern pollen-precipitation transfer function from the eastern and north-eastern Tibet-Qinghai Plateau to fossil pollen spectra from Qinghai Lake to reconstruct annual precipitation changes during the Holocene. The reconstructions are compared to a stable oxygen-isotope record from the same sediment core and to results from two transient climate model simulations. Results The pollen-based precipitation reconstruction covering the Holocene parallels moisture changes inferred from the stable oxygen-isotope record. Furthermore, these results are in close agreement with simulated model-based past annual precipitation changes. Main conclusions In the light of these data and the model results, we conclude that it is not necessary to attribute the broad-scale Forest Decline to human activity. Climate change as a result of changes in the intensity of the East Asian Summer Monsoon in the mid-Holocene is the most parsimonious explanation for the widespread Forest Decline on the Tibet-Qinghai Plateau. Moreover, climate feedback from a reduced Forest cover accentuates increasingly drier conditions in the area, indicating complex vegetation-climate interactions during this major ecological change.
Ulrike Herzschuh - One of the best experts on this subject based on the ideXlab platform.
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this article has been retracted what caused the mid holocene Forest Decline on the eastern tibet qinghai plateau
Global Ecology and Biogeography, 2010Co-Authors: Ulrike Herzschuh, Xingqi Liu, Claudia Kubatzki, John H B Birks, Gerrit LohmannAbstract:Aim Atmospheric CO2 concentrations depend, in part, on the amount of biomass locked up in terrestrial vegetation. Information on the causes of a broad-scale vegetation transition and associated loss of biomass is thus of critical interest for understanding global palaeoclimatic changes. Pollen records from the north-eastern Tibet-Qinghai Plateau reveal a dramatic and extensive Forest Decline beginning c. 6000 cal. yr bp. The aim of this study is to elucidate the causes of this regional-scale change from high-biomass Forest to low-biomass steppe on the Tibet-Qinghai Plateau during the second half of the Holocene. Location Our study focuses on the north-eastern Tibet-Qinghai Plateau. Stratigraphical data used are from Qinghai Lake (3200 m a.s.l., 36°32′–37°15′ N, 99°36′–100°47′ E). Methods We apply a modern pollen-precipitation transfer function from the eastern and north-eastern Tibet-Qinghai Plateau to fossil pollen spectra from Qinghai Lake to reconstruct annual precipitation changes during the Holocene. The reconstructions are compared to a stable oxygen-isotope record from the same sediment core and to results from two transient climate model simulations. Results The pollen-based precipitation reconstruction covering the Holocene parallels moisture changes inferred from the stable oxygen-isotope record. Furthermore, these results are in close agreement with simulated model-based past annual precipitation changes. Main conclusions In the light of these data and the model results, we conclude that it is not necessary to attribute the broad-scale Forest Decline to human activity. Climate change as a result of changes in the intensity of the East Asian Summer Monsoon in the mid-Holocene is the most parsimonious explanation for the widespread Forest Decline on the Tibet-Qinghai Plateau. Moreover, climate feedback from a reduced Forest cover accentuates increasingly drier conditions in the area, indicating complex vegetation–climate interactions during this major ecological change.
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Retracted: What caused the mid-Holocene Forest Decline on the eastern Tibet-Qinghai Plateau?
2010Co-Authors: Ulrike Herzschuh, H. John B. Birks, Xingqi Liu, Claudia Kubatzki, Gerrit LohmannAbstract:Aim: Atmospheric CO2 concentrations depend, in part, on the amount of biomass locked up in terrestrial vegetation. Information on the causes of a broad-scale vegetation transition and associated loss of biomass is thus of critical interest for understanding global palaeoclimatic changes. Pollen records from the north-eastern Tibet-Qinghai Plateau reveal a dramatic and extensive Forest Decline beginning c. 6000 cal. yr bp. The aim of this study is to elucidate the causes of this regional-scale change from high-biomass Forest to low-biomass steppe on the Tibet-Qinghai Plateau during the second half of the Holocene. Location: Our study focuses on the north-eastern Tibet-Qinghai Plateau. Stratigraphical data used are from Qinghai Lake (3200 m a.s.l., 36 degrees 32'-37 degrees 15' N, 99 degrees 36'-100 degrees 47' E). Methods: We apply a modern pollen-precipitation transfer function from the eastern and north-eastern Tibet-Qinghai Plateau to fossil pollen spectra from Qinghai Lake to reconstruct annual precipitation changes during the Holocene. The reconstructions are compared to a stable oxygen-isotope record from the same sediment core and to results from two transient climate model simulations. Results: The pollen-based precipitation reconstruction covering the Holocene parallels moisture changes inferred from the stable oxygen-isotope record. Furthermore, these results are in close agreement with simulated model-based past annual precipitation changes. Main conclusions: In the light of these data and the model results, we conclude that it is not necessary to attribute the broad-scale Forest Decline to human activity. Climate change as a result of changes in the intensity of the East Asian Summer Monsoon in the mid-Holocene is the most parsimonious explanation for the widespread Forest Decline on the Tibet-Qinghai Plateau. Moreover, climate feedback from a reduced Forest cover accentuates increasingly drier conditions in the area, indicating complex vegetation-climate interactions during this major ecological change.
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What caused the mid-Holocene Forest Decline on the eastern Tibet-Qinghai Plateau?
Global Ecology and Biogeography, 2009Co-Authors: Ulrike Herzschuh, H. John B. Birks, Xingqi Liu, Claudia Kubatzki, Gerrit LohmannAbstract:Aim Atmospheric CO 2 concentrations depend, in part, on the amount of biomass locked up in terrestrial vegetation. Information on the causes of a broad-scale vegetation transition and associated loss of biomass is thus of critical interest for understanding global palaeoclimatic changes. Pollen records from the north-eastern Tibet-Qinghai Plateau reveal a dramatic and extensive Forest Decline beginning c. 6000 cal. yr BP. The aim of this study is to elucidate the causes of this regional-scale change from high-biomass Forest to low-biomass steppe on the Tibet-Qinghai Plateau during the second half of the Holocene. Location Our study focuses on the north-eastern Tibet-Qinghai Plateau. Stratigraphical data used are from Qinghai Lake (3200 m a.s.l., 36°32'-37°15' N, 99°36'-100°47' E). Methods We apply a modern pollen-precipitation transfer function from the eastern and north-eastern Tibet-Qinghai Plateau to fossil pollen spectra from Qinghai Lake to reconstruct annual precipitation changes during the Holocene. The reconstructions are compared to a stable oxygen-isotope record from the same sediment core and to results from two transient climate model simulations. Results The pollen-based precipitation reconstruction covering the Holocene parallels moisture changes inferred from the stable oxygen-isotope record. Furthermore, these results are in close agreement with simulated model-based past annual precipitation changes. Main conclusions In the light of these data and the model results, we conclude that it is not necessary to attribute the broad-scale Forest Decline to human activity. Climate change as a result of changes in the intensity of the East Asian Summer Monsoon in the mid-Holocene is the most parsimonious explanation for the widespread Forest Decline on the Tibet-Qinghai Plateau. Moreover, climate feedback from a reduced Forest cover accentuates increasingly drier conditions in the area, indicating complex vegetation-climate interactions during this major ecological change.
Gessesse Dessie - One of the best experts on this subject based on the ideXlab platform.
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Khat expansion and Forest Decline in Wondo Genet, Ethiopia
Geografiska Annaler Series B-human Geography, 2008Co-Authors: Gessesse Dessie, Peter KinlundAbstract:This study analyses the expansion of khat productionin relation to Forest Decline in the Wondo Genet area in southcentralEthiopia. By assessing spatial variables and social factors,and using remote ...
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Forest Decline and its causes in the south-central rift valley of Ethiopia: human impact over a one hundred year perspective.
AMBIO: A Journal of the Human Environment, 2008Co-Authors: Gessesse Dessie, Carl ChristianssonAbstract:Forest Decline in Ethiopia is highlighted by several authors but there is no consensus on its causes and consequences. The objective of this study is to investigate, from sociopolitical and geographical perspectives, the linkage between the trend of Forest Decline and changes in the social, economic, and political pattern in the Awassa watershed over a 100-year perspective. Field observations, satellite image and map analyses, interviews, and literature studies were employed, and natural indicators were analyzed. The findings indicate that the Forest area Declined from about 40% at the turn of the 19th century to less than 3% in the year 2000. Forest Decline in the study area during the elected time period is the result of the combination of biophysical and social conditions. Important causes are geographic properties, sociopolitical changes, population growth, unstable land tenure principles, agricultural development, and the improvement of transport capacity. The main conclusions are as follows: Already in the early 20th century Forest Decline was in progress and Forests were attributed an insignificant economic classification. Large areas of Forest were cut down during periods of political transition when as a result of the political vacuum, interest in the protection of resources including Forests was lacking. Long-term planning efforts to manage Forests were obstructed by uncertainty resulting from land tenure principle change during each political period. The sparse area of Forest land that remains is becoming increasingly attractive as potential land for arable agriculture because of improved road access between the study area and distant markets.
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Forest Decline in South Central Ethiopia : Extent, history and process
2007Co-Authors: Gessesse DessieAbstract:This study presents the extent, history and process of Forest Decline in Awassa watershed, south central Ethiopia. By combining different data sources such as satellite images, social surveys and h ...
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Ecological and human spatial boundaries and their impact on Forest management and Forest Decline in Wondo Genet, Ethiopia
2007Co-Authors: Gessesse Dessie, Johan KlemanAbstract:Ecological and human spatial boundaries and their impact on Forest management and Forest Decline in Wondo Genet, Ethiopia
Werner Schmidt - One of the best experts on this subject based on the ideXlab platform.
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Time-Resolved Chlorophyll Fluorescence for Monitoring of Forest Decline
Laser in der Umweltmeßtechnik Laser in Remote Sensing, 1994Co-Authors: Herbert Schneckenburger, Werner SchmidtAbstract:Aiming at clues of Forest Decline we studied prompt and delayed luminescence of spruce needles from the picosecond to the second time range using various custom made kinetic equipments. Both kinetics in the picosecond and in the seconds time range could be fitted by three exponentially decaying components yielding three amplitudes and three reaction constants each. Basically, all components showed a typical annual time course, independent of the degree of damage or air pollution. In addition, it turned out that on one hand the “slow” component of picosecond decay kinetics (decay time τ = 2.0–3.5 ns) reflects some damage of the photosynthetic apparatus, which is mainly located in photosystem II. Similarly, in long term delayed luminescence in the seconds time range the “fast” component (decay time τ = 0.13 s) obviously carries some information on the spruces’ vitality. In general, healthy or Declined spruces showed the highest photosynthetic efficiencies but also the most pronounced stress symptoms during the summer period — probalby due to high irradiance, drought and increased ozone concentrations.
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Time-resolved chlorophyll fluorescence for early detection of Forest Decline
Laser Study of Macroscopic Biosystems, 1993Co-Authors: Herbert Schneckenburger, Werner SchmidtAbstract:Aiming to an early detection of Forest Decline, prompt and delayed luminescence of spruce needles was studied from the picosecond to the second time range using novel laser diodes and highly sensitive detection systems. In particular, (1) subnanosecond fluorescence decay measurements showed a superposition of at least three exponentially decaying components, the largest of which (decay time (tau) equals 2.0 - 3.5 ns) represented some `dead' chlorophyll or closed reaction centers. This component is more pronounced in slightly damaged than in healthy spruces and can be used to monitor the early steps of photosynthesis. (2) Delayed luminescence -- which is supposed to report on the electron transport chain as a whole -- could also be correlated with the physiological state of the individual spruce. In general, healthy and Declined spruces showed the highest photosynthetic efficiencies during the summer period, but also the most pronounced stress symptoms -- probably due to high irradiance, drought, and increased ozone concentrations.
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Fluorescence in Forest Decline Studies
Fluorescence Spectroscopy, 1993Co-Authors: Herbert Schneckenburger, Werner SchmidtAbstract:Plants have to cope with various stress factors such as environmental pollutants, mineral deficiencies, climate or parasite infection giving rise to the current phenomenon of “Forest Decline”. To assess the various impacts of these stress factors, complex biochemical procedures are mostly utilized demanding damage to the specimen and fairly high sample concentrations. In contrast to these, spectroscopic methods offer many advantages. They are fast, non-invasive, easy to perform, highly selective for specific plant pigments, and require only small samples.
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Fiber optic and time-resolving techniques in Forest Decline research
Environment and Pollution Measurement Sensors and Systems, 1990Co-Authors: Werner Schmidt, Herbert SchneckenburgerAbstract:ABSTRACT Three novel techniques of fiber—optic spectroscopy have been recently introduced into research of Forest Decline. These include measurement of luminescence changesand fluorescence—decay of chiorophylls (i) under continuous irradiation, and after pulse—induction in the (ii) long—term and the (iii) picosecond time range. These chan— ges will be correlated both with environmental factors such as air pollutants, soil, fertilization and various experimental and physiological conditions. 1 . INTRODUCTION Plants have to cope with environmental pollutants and mineral deficiencies as ubi— quitous stress factors throughout the world, particularly in Forestry and arboriculture. To access the various environmental impacts for early diagnosis of the status of Forest Decline most often laboratory—bound, in vitro "wet analytical procedures" suchas chromatography, atomic absorption and emission spectroscopy and colorimetry areemployed, requiring laborious extraction procedures and —most important— damage of
Xingqi Liu - One of the best experts on this subject based on the ideXlab platform.
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this article has been retracted what caused the mid holocene Forest Decline on the eastern tibet qinghai plateau
Global Ecology and Biogeography, 2010Co-Authors: Ulrike Herzschuh, Xingqi Liu, Claudia Kubatzki, John H B Birks, Gerrit LohmannAbstract:Aim Atmospheric CO2 concentrations depend, in part, on the amount of biomass locked up in terrestrial vegetation. Information on the causes of a broad-scale vegetation transition and associated loss of biomass is thus of critical interest for understanding global palaeoclimatic changes. Pollen records from the north-eastern Tibet-Qinghai Plateau reveal a dramatic and extensive Forest Decline beginning c. 6000 cal. yr bp. The aim of this study is to elucidate the causes of this regional-scale change from high-biomass Forest to low-biomass steppe on the Tibet-Qinghai Plateau during the second half of the Holocene. Location Our study focuses on the north-eastern Tibet-Qinghai Plateau. Stratigraphical data used are from Qinghai Lake (3200 m a.s.l., 36°32′–37°15′ N, 99°36′–100°47′ E). Methods We apply a modern pollen-precipitation transfer function from the eastern and north-eastern Tibet-Qinghai Plateau to fossil pollen spectra from Qinghai Lake to reconstruct annual precipitation changes during the Holocene. The reconstructions are compared to a stable oxygen-isotope record from the same sediment core and to results from two transient climate model simulations. Results The pollen-based precipitation reconstruction covering the Holocene parallels moisture changes inferred from the stable oxygen-isotope record. Furthermore, these results are in close agreement with simulated model-based past annual precipitation changes. Main conclusions In the light of these data and the model results, we conclude that it is not necessary to attribute the broad-scale Forest Decline to human activity. Climate change as a result of changes in the intensity of the East Asian Summer Monsoon in the mid-Holocene is the most parsimonious explanation for the widespread Forest Decline on the Tibet-Qinghai Plateau. Moreover, climate feedback from a reduced Forest cover accentuates increasingly drier conditions in the area, indicating complex vegetation–climate interactions during this major ecological change.
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Retracted: What caused the mid-Holocene Forest Decline on the eastern Tibet-Qinghai Plateau?
2010Co-Authors: Ulrike Herzschuh, H. John B. Birks, Xingqi Liu, Claudia Kubatzki, Gerrit LohmannAbstract:Aim: Atmospheric CO2 concentrations depend, in part, on the amount of biomass locked up in terrestrial vegetation. Information on the causes of a broad-scale vegetation transition and associated loss of biomass is thus of critical interest for understanding global palaeoclimatic changes. Pollen records from the north-eastern Tibet-Qinghai Plateau reveal a dramatic and extensive Forest Decline beginning c. 6000 cal. yr bp. The aim of this study is to elucidate the causes of this regional-scale change from high-biomass Forest to low-biomass steppe on the Tibet-Qinghai Plateau during the second half of the Holocene. Location: Our study focuses on the north-eastern Tibet-Qinghai Plateau. Stratigraphical data used are from Qinghai Lake (3200 m a.s.l., 36 degrees 32'-37 degrees 15' N, 99 degrees 36'-100 degrees 47' E). Methods: We apply a modern pollen-precipitation transfer function from the eastern and north-eastern Tibet-Qinghai Plateau to fossil pollen spectra from Qinghai Lake to reconstruct annual precipitation changes during the Holocene. The reconstructions are compared to a stable oxygen-isotope record from the same sediment core and to results from two transient climate model simulations. Results: The pollen-based precipitation reconstruction covering the Holocene parallels moisture changes inferred from the stable oxygen-isotope record. Furthermore, these results are in close agreement with simulated model-based past annual precipitation changes. Main conclusions: In the light of these data and the model results, we conclude that it is not necessary to attribute the broad-scale Forest Decline to human activity. Climate change as a result of changes in the intensity of the East Asian Summer Monsoon in the mid-Holocene is the most parsimonious explanation for the widespread Forest Decline on the Tibet-Qinghai Plateau. Moreover, climate feedback from a reduced Forest cover accentuates increasingly drier conditions in the area, indicating complex vegetation-climate interactions during this major ecological change.
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What caused the mid-Holocene Forest Decline on the eastern Tibet-Qinghai Plateau?
Global Ecology and Biogeography, 2009Co-Authors: Ulrike Herzschuh, H. John B. Birks, Xingqi Liu, Claudia Kubatzki, Gerrit LohmannAbstract:Aim Atmospheric CO 2 concentrations depend, in part, on the amount of biomass locked up in terrestrial vegetation. Information on the causes of a broad-scale vegetation transition and associated loss of biomass is thus of critical interest for understanding global palaeoclimatic changes. Pollen records from the north-eastern Tibet-Qinghai Plateau reveal a dramatic and extensive Forest Decline beginning c. 6000 cal. yr BP. The aim of this study is to elucidate the causes of this regional-scale change from high-biomass Forest to low-biomass steppe on the Tibet-Qinghai Plateau during the second half of the Holocene. Location Our study focuses on the north-eastern Tibet-Qinghai Plateau. Stratigraphical data used are from Qinghai Lake (3200 m a.s.l., 36°32'-37°15' N, 99°36'-100°47' E). Methods We apply a modern pollen-precipitation transfer function from the eastern and north-eastern Tibet-Qinghai Plateau to fossil pollen spectra from Qinghai Lake to reconstruct annual precipitation changes during the Holocene. The reconstructions are compared to a stable oxygen-isotope record from the same sediment core and to results from two transient climate model simulations. Results The pollen-based precipitation reconstruction covering the Holocene parallels moisture changes inferred from the stable oxygen-isotope record. Furthermore, these results are in close agreement with simulated model-based past annual precipitation changes. Main conclusions In the light of these data and the model results, we conclude that it is not necessary to attribute the broad-scale Forest Decline to human activity. Climate change as a result of changes in the intensity of the East Asian Summer Monsoon in the mid-Holocene is the most parsimonious explanation for the widespread Forest Decline on the Tibet-Qinghai Plateau. Moreover, climate feedback from a reduced Forest cover accentuates increasingly drier conditions in the area, indicating complex vegetation-climate interactions during this major ecological change.