According to an analysis published on
ScienceWatch.com in May, Dr. Markus Reichstein has
been named a
in the field of Environment & Ecology. His current
citation record in this field in Essential Science
Reuters includes 26 papers cited a total of 611
times between January 1, 1998 and April 30, 2008. He
also has Highly Cited Papers in the fields of
Agricultural Sciences and Geosciences.
Dr. Reichstein is the Leader of the
Biogeochemical Model-Data Integration Group at the Max-Planck
Institute for Biogeochemistry in Jena. In the interview below,
he talks with us about his work involving Earth system
Please tell us a little about your research and
The research I am doing can be considered as part of the current Earth
System Science endeavor, where we are trying to understand the dynamics and
interactions between the major components ("spheres") of our planet Earth,
i.e. atmosphere, biosphere, hydrosphere including oceans, the cryosphere,
and the humans (anthroposphere). This field of research is quite young and
has been in existence for only a few decades, when the Earth was perceived
as a whole system. I think both the satellite observation from space (the
first photograph coming from Apollo) as well as the development of the Gaia
theory by James Lovelock (the Earth as a self-regulating system with the
biosphere as major actor) contributed to this new understanding.
I am particularly looking at the interactions between the subsystems
atmosphere and terrestrial biosphere (vegetation and soils). One important
diagnostic or test case of whether we understand the interactions within
the Earth System is the global carbon cycle, since carbon is resident and
processed in large quantities in all spheres and obviously the major
element of all living and dead organic material. Moreover, carbon interacts
with the climate system by absorbing long-wave radiation as carbon dioxide
or methane (greenhouse effect), implying a high significance of the carbon
cycle for applied topics such as global climate change.
"The European heat wave of 2003 not
only caused thousands of human casualties,
but also strongly stressed the terrestrial
To be successful in this field a broad interdisciplinary and quantitative
natural and geoscience background is very helpful. It is interesting to
note that at first glance our field largely relies on physicochemical
principles of the 19th century (there are no relativistic or
quantum effects to be considered), but the challenge is that we are working
with very complex systems that are far from thermodynamic equilibrium.
Hence, system-oriented and mathematical education and talent are very
important. Last but not least, processes always happen in a spatially
distributed way at various space scales, i.e., spatial expertise, e.g.,
through Geostatistics and Geography, is another critical asset.
I studied Landscape Ecology (often also called Geoecology) with Botany,
Physical Chemistry, and Mathematics/Information Science as minors at the
University of Münster, Germany, graduated with a soil ecological
Diploma thesis, and then continued with my Ph.D. work at the Department of
Plant Ecology at the University of Bayreuth.
What do you consider the main focus of your research,
and what drew your interest to this particular area?
My current main focus is to analyze how the biosphere/ecosystems react to
climate variability, i.e., changes in temperature but particularly in water
balance (e.g., drought). One crucial observational tool is the direct
observation of carbon dioxide, water vapor, and energy fluxes between
ecosystems and the atmosphere, which has been accomplished for roughly the
past 10 years in a global flux observation network
FLUXNET (cf). We try to link these observations to
satellite remote sensing of the terrestrial vegetation, watershed runoff
data, and atmospheric CO2 concentration observations to give
a regionally-to-globally integrated picture of the "breathing of the
biosphere." Hence, one important aspect of the research is to develop
data analysis and numerical modeling approaches, which extract the
maximum from this plethora of existing and ongoing observations, which
contain complementary information.
One big unknown and "final frontier" is what is happening below ground,
i.e., in the soil. Soil contains about four times more carbon than the
atmosphere, and annual global soil respiration fluxes are, for example,
10-fold higher than human fossil fuel CO2 emissions. While these
respiration processes are performed by soil organisms operating in a very
heterogeneous environment, the representation of the soil in current Earth
System models is oversimplified and largely neglects the role of biological
mechanisms. Thus, in my group we are dedicating large part of our research
to overcoming this "dead-soil paradigm."
In our approach we find it crucial to integrate data-oriented modeling
techniques (e.g., data mining techniques, machine learning), which allow
almost "assumption-free" exploration of patterns in the data, and
process-oriented modeling approaches (reductionistically based on physical
and biological theoretical principles), which is also reflected in the name
of the research group (Biogeochemical Model-Data Integration Group) that I
am currently leading at the Max-Planck Institute for Biogeochemistry,
One of your most-cited papers in our database is the
2005 Nature article, "Europe-wide reduction in primary
productivity caused by the heat and drought in 2003." Would you walk
our readers through this paper and its findings?
The European heat wave of 2003 not only caused thousands of human
casualties, but also strongly stressed the terrestrial biosphere. It can be
viewed as a natural experiment that let us better understand the response
of vegetation and soils to climate variability and extremes. Using
integrated observation and modeling systems as described above, for the
first time we could quantify the impact of such a dry summer on the
terrestrial carbon balance at continental scale. The main two lessons
learned were that water as a factor in limiting vegetation and ecosystem
productivity is becoming more and more widespread under such conditions (as
opposed to temperature effects mostly discussed so far) and that extreme
climate events may easily offset any beneficial effect of warming and
rising CO2 concentrations on vegetation productivity.
"Sometimes it strikes me a bit
ironic that vast amounts of public money and
intellectual capacity is spent for
investigating life on Mars, while we still
have quite limited understanding about the
In the case of the 2003 heat wave we found that this single event undid
five years of carbon uptake by the European terrestrial
ecosystems—lag effects like tree mortality were not even accounted
for. Given that in the future heat waves will become more frequent
according to climate model simulations, one might seriously doubt about a
continuation of the carbon absorption by the temperate forest ecosystems,
which has previously been inferred from temperature-related prolongation of
the growing season.
Another of your highly cited papers, the 2005 Global
Change Biology paper, deals with algorithms for net ecosystem
exchange. Would you please talk a little about this aspect of your
This paper is a methodological contribution to the above-mentioned FLUXNET,
the worldwide observation network of ecosystem-atmosphere CO2,
H2O, and energy exchange. Analogous to other observation
networks like meteorological or astrophysical networks, one crucial aspect
is the generation of standardized data products. In this paper an efficient
algorithm is presented to separate the net fluxes of carbon dioxide into
the major components of gross photosynthetic assimilation by the vegetation
and whole-ecosystem respiration, leading to a better process-understanding
of the reaction of the terrestrial carbon cycle to climate and other
perturbations. Additionally an algorithm to fill gaps inherent in the flux
data is presented there. The content of the paper now builds the basis for
the global processing of FLUXNET data that is performed in collaboration
with my colleague Dario Papale at the University of Tuscia, Viterbo, Italy.
Where do you see this research going in five to ten
We are just at the beginning of learning about manifold role of the
biosphere (vegetation and soils) for global and regional climate,
biogeochemical cycles, and the Earth System in general. I hope in five to
ten years we will have been able to represent this role adequately in a new
generation of Earth system models. I believe we will make particular
progress with respect to soil carbon processes by turning the current
"dead-soil paradigm" into a "living-soil" paradigm.
Moreover, new observation systems and more intimate integration of current
ground-based with satellite remote sensing and paleo-observations will
hopefully allow us to get deeper insight into various landsurface and
What should the "take-away lesson" about your work be
for the general public?
There is no doubt that we as humans are globally changing the Earth System
(most prominently known the climate), which has led to the term
"anthropocene" by Chemistry Nobel Laureate P. Crutzen. We definitely need
to know more about the crucial system dynamics within our Planet Earth.
Earth System Science is both intellectually challenging, and may be
necessary to guarantee continued "sustainable" human welfare. Sometimes it
strikes me a bit ironic that vast amounts of public money and intellectual
capacity is spent for investigating life on Mars, while we still have quite
limited understanding about the Living Earth.
Biogeochemical Model-Data Integration Group (SNWG)
Max-Planck-Institute for Biogeochemistry Jena
Reichstein's most-cited paper
with 135 cites to date:
Ciais P, et al., "Europe-wide reduction in primary
productivity caused by the heat and drought in 2003,"
Nature 437(7058): 529-33, 22 September 2005.
Source: Essential Science Indicators from Thomson