Tree-Ring Talk

Accounting for non-stationarity when analyzing ecological time series

Increasingly studies highlight the non-stationary features of population dynamics. For instance, recent studies have shown that population dynamics can switch between different dynamics at multi-decadal scales, triggered by small environmental changes. These regime shifts were observed in different regions for different species. Transient behaviors in population dynamics have also been documented in epidemiology. Long-term changes in climate, human demography and/or social features of human populations have considerable effects on the dynamics of numerous epidemics.

Millennial–length tree–ring records: A basis for climate reconstruction an assessment of climate extremes and trends at local to global scales

(Multi-) proxy temperature reconstructions over the Common Era are crucial not only to place current temperature trends in a long-term context, but also to assess the full range of natural and anthropogenic climate forcings. However, estimates of the first millennium remain poorly constrained due to a paucity of millennial long tree-ring records causing a spatial under-representation of some regions in larger scale climate reconstructions and increasing uncertainty in the interpretation of climatic trends and extremes.

Population dynamics in a changing world: The consequences of environmental variation for species with complex life histories

Population dynamics in a changing world: the consequences of environmental variation for species with complex life histories Despite increasing awareness of the importance of environmental variation in ecological systems, there are still many open questions about how variation affects population dynamics. I studied several aspects of environmental variation and the roles it plays in population dynamics, particularly for species with complex life histories: (1) How do the the effects of native insect herbivores on the population dynamics of an invasive thistle vary across space?

FTIR spectroscopy as a potential tool in dendroarchaeology

Infrared spectroscopy is a well proven tool in the assessment of molecular structures. The presentation elaborates applications of this method to archaeometric questions. The main focus will be set on the prediction of sample age. Currently, dating tools are worked out best for wood. But also the possibilities for other materials are presented.

Reconstructing past marine variability using the longest-lived animals on Earth

Variability in the North Atlantic Ocean plays a significant role in moderating atmospheric climate variability over large portions of the Northern Hemisphere. However, there remain large uncertainties in our understanding of how the North Atlantic Ocean has varied in the past and the role of external forcings and internal mechanisms in driving this variability. These uncertainties largely stem from the short temporal and spatially heterogeneous nature of direct observations, that are typically constrained to the past 50 years.

Recent methodological advances of isotope dendroclimatology in Japan

In this talk, I would like to introduce four topics, (1) how we sample increment cores by using cordless impact wrench, (2) how to estimate the geographic origin of wood using tree-ring carbon and oxygen isotopes, (3) how to make the cellulose extraction process for tree-ring isotope analysis more efficient, and (4) how spring, summer and autumn photoassimilates are used for tree-ring formation.

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