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Trumbore Department (Prozesses)
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Abstract
Biogeochemical processes are the actions that trasform and distribute the elements essential to life among
the atmosphere, biosphere, land and oceans. In the Department of Biogeochemical Processes we develop
and apply a range of experimental and analytical tools to quantify the rates and global importance of key
processes governing the exchange of carbon, oxygen, nitrogen and phosphorous between ecosystems and the
atmosphere. We explore how these cycles have changed because of human activity, how they alter
greenhouse gases in the atmosphere, and how they interact with a changing climate.
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Terrestrial ecosystems – plants, animals, and soils - both influence and are impacted by changes atmospheric
composition and climate. During the last centuries, humans have increasingly modified the land surface,
fundamentally altering ecosystems and the rates at which energy, water, carbon, nitrogen, and phosphorous
cycle through them. The impact of these changes contributes to climate change and affects soil fertility,
water availability, and air and water quality. In the Department of Biogeochemical Processes, we study the
basic science of how ecosystems process energy, water and elements – and how human land use changes
like deforestation and agriculture have altered those functions with global consequences. This research
explores basic properties of ecosytstems and ecology, and informs future land management strategies.
Terrestrial ecosystems are undergoing rapid change in many parts of the globe, adding urgency to our work.
Much of the emphasis on ecosystem changes has focused on direct human management of land, such as
deforestation or agriculture. However, evidence is accumulating that changes in climate and the supply of
nutrients like nitrogen and CO2 from the atmosphere are already having global effects. There are
documented changes in the timing of spring leaf-out and animal migration patterns associated with climate
change, and increasing evidence of warming-induced vegetation change in high northern latitidues.
Nitrogen deposition and high ozone levels associated with pollution as well as elevated CO2 levels all have
been shown to affect plant growth rates, though it is uncertain what the net effects are globally. The
introduction of new species, including herbivores and pathogens, is altering the makeup of communities that
co-evolved with their local environment over many millennia. Changes in the frequency and severity of
disturbances such as fire or severe storms, when combined with management practice, drought, and insect
infestation, are pushing some ecosystems towards thresholds that will rapidly and perhaps irreversibly alter
the makeup and diversity of plant and soil communities. Our ultimate goal is to predict how such changes
will affect the biogeochemical functions of ecosystems – how they affect the availability and quality of
water, the fertility of soils, and how they feed back to influence climate.
In the Department of Biogeochemical Processes, we address this complex problem with a range of tools and
approaches. In the field, we measure the exchange of gases like carbon dioxide, methane and nitrous oxide
between the land and atmosphere and document how those fluxes vary with climate and plant or microbial
community compostion (FIGURE OF VARIOUS FLUX MEASUREMENT DEVICES IN THE FIELD).
Studies of fluxes along spatial gradients in ecosystem properties, for example, temperature gradients
associated with elevation, allow us to document relationships between climate and ecosytem fluxes that
evolve over longer time scales. Laboratory and field experiments (FIGURE OF FIELD MANIPULATION?)
manipulate individual factors such as temperature or nutrient availability in order to document how
components of the ecosystems respond to environmental conditions, and how these combine to create the
whole ecosystem patterns of response. We develop new analytical tools using isotopes or other tracers that
allow us to evaluate the importance of processes across a range of spatial scales.
Research in the Department of Biogeochemical Processes integrates with the other Departments in the
Institute. We work closely with the Central Facilities to develop new analytical tools to quantify fluxes and
their controls across spatial scales. The process understanding we gain is used, in collaboration with the
Modeling groups, to improve global estimates of the changing role of terrestrial ecosytsems. Tracers of
specific processes such as those that discriminate isotopes or emit specific trace gases, are combined with
global atmospheric observations of atmospheric composition in the Department of Biogeochemical
Integration. These interactions help identify where critical gaps in understanding exist and help design the
experiments to close those gaps.
The Department of Biogeochemical Processes is currently in transition to a new Director. Under the
leadership of founding Director, Professor E-D Schulze, a major emphasis has been the role of terrestrial
ecosytems in the global and European carbon cycles. This emphasis will continue, though specifics of new
projects are still in the planning stages. New experiments and field research will focus on processes and
ecosystems where significant uncertainties limit our ability to predict the future, and where large responses
to climate change or direct human management might be expected in the coming century.
Focus area 1. The origin, fate and vulnerability of organic matter stored in soils.
(Gleixner, Schrumpf) Soils store more than twice as much carbon in organic matter as does vegetation,
which make it an important component of the global carbon cycle (FIGURE OF SOIL PROFILE WITH
CARBON CYCLE). Organic matter decomposition provides the major source of nutrients for plant growth
in many ecosystems and loss of organic matter, for example, under agricultural management, can severely
limit soil fertility. Decomposition processes are also major sources and sinks of greenhouse gases
likecarbon dioxie, methane and nitrous oxide. In spite of its importance to human well-being and to a
number of global biogeochemical cycles, we still lack fundamental understanding of how and why organic
matter is stabilized in soils, and how factors such as climate, organisms, and mineral composition combine
to determine how long it is stored before ultimately lost to decomposition, erosion or leaching. Particular
projects focus on the vulnerability of high-latitude organic matter to rapid decomposition with permafrost
melting and change from tussock tundra to shrubland, determining whether changes in soil carbon can be
detected and attributed to climate or management change, and assessing the potential of soil amendment
with biochar to alter soil fertility or chemistry.
Focus area 2. Understanding plant allocation and respiration pathways.
While photosynthesis, a single process, is responsible for uptake of CO2 from the atmosphere by ecosystems,
the pathways returning C to the atmosphere are complex and occur over a range of timescales. Plants use
the stugars made by photosynthesis for respiration, growth, defense, transfer to symbionts, or storage, but we
do not have good theories to predict how allocation strategies among those pathways are determined, or how
those allocation patterns will respond to changes in environmental conditions. We have developed methods
for tracking allocation pathways and the residence time of carbon in plants in field experiments and will
design experiments to detect shifts in allocation with climate and nutrient availability. Of particular interest
are the storage reserves that allow plants to survive damage, including how long it takes for those reserves to
be replenished and their role in plant mortality.
Focus area 3. Documenting and predicting thresholds in ecosystems.
While we can measure exchange of carbon and other trace gases between land and atmosphere at the plot
scale, we cannot simply assume that the same processes controlling fluxes at these scales will dominate at
larger spatial scales, or even on longer timescales. For example, on landscapes where succession is
dominated by fire, the balance of carbon uptake and loss at the regional scale depends on how the carbon
lost in fire balances the carbon gained in stands that are recovering from fire. Responses of vegetation or
soils to factors like warming or CO2 fertilization will interact with this disturbance-recovery dynamic.
Ongoing investigations study the boreal forest ecosystems and their recovery from fire. We will begin new
collaborative projects to investigate the role of wind disturbance in tropical forests as a regional control of
carbon fluxes. These studies will use remote sensing tools to quantify disturbance regimes across large
biomes like tropical forests to guide our field flux measurements and allow us to integrate those spatial
variations into a regional context.
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Portait of Leader/Director: 542 Zeichen mit Leerzeichen
Susan Trumbore will assume Directorship of the Department of Biogeochemical Processes in October, 2009.
Trumbore comes to MPI-BGC from the University of California, Irvine where she is Professor and past
Chair of the Department of Earth System Science. Trumbore’s areas of expertise are in using isotopes to
quantify the processes and timescales controlling the exchange of greenhouse gases between the atmosphere
and terrestrial plants and soils, including detection of alterations in terrestrial carbon cycling associated with
climate and land use change. She works in a range of ecosystems, from tropical forests and savannahs to
tundra.
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Figure legends: 141 Zeichen mit Leerzeichen
Figure 1. I suggest this be a collection of photos of various instrumentation for flux measurements: the
Hainich tower, soil chambers, peat incubations. (I do not have any of these).
Figure 2. Picture of a field manipulation (for now that could be the Jena experiment, since that will continue
with Gleixner? )
Possible Figure 3. Soils contain large stores of carbon as organic matter. We are using a variety of
analytical methods to trace the processes that stabilize carbon in soils, in particular how vulnerable those
stores are to future climate changes
(NB. This figure is copyrighted, we should re-draw it a bit if it is to be used)
Possible Figure. 4. Studies of the role of plant sugars and starches contrast deciduous and evergreen oaks.
Carbon reserves up to a decade old are used by these trees to fuel root respiration and to survive catastrophic
events like fire. Increases in fire frequency may impact the ability of these plants to resprout and recover.
Possible Figure - Picture of blow-down in tropical forest