International tree mortality network

Seminars

Online seminars

We are hosting a series of online seminars in regular 6–8 week intervals. 

Upcoming meetings and records of past events are posted here. 

Past events

Our #6 ITMN seminar took place on June 22 (1700 CEST)  We are happy to announce our speaker: 

CRAIG D. ALLEN

The global emergence of hotter-drought drivers of forest disturbance tipping points

Abstract: Current research is presented on global-scale patterns and trends of forest responses to increasingly hotter droughts, particularly extensive tree mortality and forest die-offs involving a range of interactive disturbances (e.g., water stress, insect outbreaks, high-severity wildfire). Diverse cross-scale observations and empirical findings increasingly indicate that amelioration of hotter-drought stress via fertilization of photosynthesis from elevated atmospheric CO2 concentrations may soon be overwhelmed by heat and accelerated atmospheric drought. These findings highlight some current challenges in realistically projecting the future of global forest ecosystems (and their associated carbon pools and fluxes) with process-based Earth system models. In particular there is substantial evidence that forests dominated by larger, older trees may be disproportionately vulnerable to increased growth stress and mortality under hotter-drought conditions. The fates of these old trees in response to global change are of vital importance, given that they are essential as: a) disproportionately large carbon sinks; b) among the most biodiverse and rare terrestrial ecosystems; c) irreplaceable archives of environmental history; and d) venerated for many cultural reasons. Key scientific uncertainties that impede modeling progress are outlined, and examples of promising empirical modeling approaches are illustrated.

Here the recording of Craig’s presentation. Enjoy!

Our #5 ITMN seminar took place on May 6 (1700 CEST)  We are happy to announce our speaker: 

LISA HÜLSMANN

Tree mortality modeling – a tool for ecological inference and a challenge for projecting forest dynamics

Abstract: Tree death is ubiquitous in forests, even without climate change, and has a lasting impact on forest structure, species composition, biomass, and biodiversity. By relating tree mortality and other vital rates to tree, forest, and environmental conditions, we can therefore identify the mechanisms that govern the shape of forest ecosystems. In turn, these empirical relationships can be useful for projecting future forest dynamics and range limits of tree species. In the talk, I will discuss empirical tree mortality models as a diagnostic opportunity and a modeling challenge through two examples: the role of conspecific negative density dependence (Janzen-Connell effects) for tree diversity and the tighter coupling of dynamic vegetation models to forest data.

Here the recording of Lisa’s presentation. Enjoy!

Our #4 ITMN seminar took place on Mar 24 (900 MDT) We are happy to announce our speaker: 

NATE MCDOWELL

natemcdowell

Rising tree mortality in the Anthropocene

Abstract: Tree mortality is rising in most documented locations but the drivers and mechanisms of this trend are unknown. Changes in atmospheric carbon dioxide, temperature, and vapor pressure deficit, along with drought, are primary potential drivers. Mechanisms linking these drivers to mortality include water, carbon, and pathogen defense processes. These processes are interdependent such that failure of one can lead to failure of the others. Prediction of future mortality is challenged by our understanding of the mechanisms, however, some evidence suggests the growing mortality rates are likely to continue well into the future. I conclude by reviewing the numerous challenges and opportunities for predicting future tree mortality.

Here the recording of Nate’s presentation. Enjoy!

 

Our #3 ITMN seminar took place on Feb 23 (900 Sydney) We are happy to announce our speaker: 

BELINDA MEDLYN

Tree mortality in Australian ecosystems: past, present and future

Abstract: Australia is not only the driest inhabited continent, it also experiences high interannual variability in rainfall, and severe multi-year droughts. Tree death from drought is thus a recurring feature of the Australian landscape. In this talk I will review our current understanding of drought mortality in Australian ecosystems, including the historical context, current field research on the extent and mechanisms of drought dieback and recovery, and the development of models to predict future drought mortality risk.

Here the recording of Belinda’s presentation. Enjoy!


Our #2 ITMN meeting took place on Jan 19 (4 pm, CET) and we are happy to announce our  speaker: 

FLÁVIA COSTA

Tree mortality in the Amazon across local hydrological gradients: how water table depth may save or condemn trees as climate changes

Abstract: Dr Costa will present results of 20 years of investigation on patterns of forest response to soil hydrology (more specifically water table depth) during normal and extreme climatic years to examine the hypothesis that shallow water tables buffer forests from droughts and forests in these conditions may even be benefited by droughts. Dr Costa will also present some data on the hydraulic trait distributions along hydrological gradients to analyse the shifting implications to mortality during moderate to strong droughts.

Here the recording of Flavia's presentation. Enjoy!

Our kick-off meeting was taking place on Nov 17 (5 pm, CET) with our first speaker:

MATT HANSEN

Global forest monitoring using satellite data

Abstract: Earth observation data enable the monitoring of forest extent and change from national to global scales. Consistent processing of time-series images has made possible the operational production of global tree cover extent, loss and gain products.  However, attribution of dynamics in the context 1) reference state, for example forest type, 2) change factor, for example fire or logging, and 3) outcome, for example land use type or natural recovery, is more challenging.   In addition to mapping, the requirement to perform robust sample-based analyses to report on all themes is underappreciated.  This talk will review our work on characterizing forest dynamics at the global scale using multi-source satellite imagery, including mapping and sampling, in the context of current operational versus future aspirational capabilities.

Here the recording of Matt's Seminar. Enjoy!

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Past Workshops

Virtual Tree Mortality Workshops 2020

We organize a series of virtual discussions to merge and harmonize different data sources on tree mortality.