Background
Since
the industrial revolution, human activities such as land-use,
over-exploitation of natural resources, burning of fossil fuels and
pollution, are changing global ecosystems and causing an accelerating
loss in biodiversity. Contemporary climate change is an
important part of this mechanism. Mountain areas are especially sensitive
to the impact of climate change, because their steep altitude
gradients create pronounced local climate zones in short distances
(such as the tree line). Small variations in
climate can cause rapid displacements of these boundaries and impact
the functioning of the local ecosystem. Because mountain areas are
important carbon sinks, these changes may also have global effects, such as changes in carbon flux
between the atmosphere and the terrestrial biosphere, which might accelerate or slow down global climate change.Several studies have shown recent changes in the composition and distribution of biological communities, caused by climate change. Most of these studies deal with plants or animals. However, microorganisms, including bacteria, archaea, fungi and microbial eukaryotes, are also important players in the soil ecosystem, often adapting faster to changing environmental conditions and directly influence plant communities. This makes microorganisms ideal as indicators for soil and ecosystem health. Yet, relatively little is known about how climate change impacts the soil microbial communities.
The Microbial Observatory
Through
the projects MicrObs and Behatoki, hosted at the Soil
Microbial Ecology Group (SMEG) of
NEIKER-Tecnalia, a
microbial observatory was
established along an altitude gradient in the Ordesa and Monte Perdido National Park,
located in the Pyrenees.
The aim of this observatory is to monitor how the properties of the
soil microbial community changes with temperature along the altitude
gradient, as well as other factors like pH, nutrient availability,
weather patterns and random heterogeneity. By studying the diversity,
composition and function along this gradient, the aim is to predict
how future changes in climate can impact mountain ecosystems like the
one studied, on a global as well as local level.
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| Sampling stations of the MicrObs Microbial Observatory |
Until
recently, in-depth studies of microbial community composition in
natural environments have been held back by technological
limitations. Advancements in molecular analysis methods, mainly DNAsequencing, now allow them.
MicrObs takes advantage of this, currently using the Illumina
MiSeq sequencing
platform. Preliminary data (approximately 100 samples) suggests high
levels of local heterogeneity, but show promising results for the
general approach.
Sampling of the Microbial Observatory
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| Soil transplanted to lower altitude |
The
MicrObs observatory consist of twelve sampling stations along an
altitude gradient spanning from 1,500 – 2,600 m. Since the
establishment of the observatory in 2011, samples have been collected yearly in late August or early September, and is planned
to continue indefinitely, given sufficient funding. Several samples have also been taken at other times in the year, earlier and later during
the summer, during the late autumn and late spring, above and under
snow cover. Together with temperature data, measured
continuously at all sampling stations, this allows us to study the
temporal dynamics of the microbial community throughout the year, as well as
changes from one year to another. To simulate the effect of climate
change, transplantation experiments have also been done, moving soil
from higher to lower altitudes and studying the change in community
structure and function after one and two years. Spatial replicates
have also been collected, including a grid experiment, to study the
spatial heterogeneity
of the microbial communities.
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