Daniel Rieker (Doctoral student)
Ph.D.
Student, since
2020 Goethe-University
Frankfurt
M.Sc.
Landscape ecology, 2016-019 University
of Münster
B.Sc.
Geography, 2012-2016 University
of Augsburg
Research
Interest
My research
interests are the reciprocal interactions among ecosystems and species, predominantly
plants, lichens, and bryophytes in cultivated landscapes. Due to an increasing transformation
of ecosystems by human activities, biodiversity is endangered. Each ecosystem
has a specific biodiversity threshold down to which ecosystem processes and
functions are performed and to maintain resilience. Below this biodiversity threshold,
these processes are impeded, and the ecosystem changes. Hence, I am keen to
investigate what drives biodiversity and develop evidence-based conservation
recommendations to achieve the goals of different nature conservation
strategies. For this, I am interested in comparing the diversity of organisms
across systematic kingdoms on temporal and spatial scales and along use-intensity
gradients.
Forest
ecosystems are among the most anthropogenically modified ones. Besides homogenization
and fragmentation, the logging of trees has a crucial impact on forest
biodiversity. Saproxylic communities are highly diverse, and their habitat
abundance decreased by a decline in deadwood volume and heterogeneity. Since
these communities drive decomposition and soil formation, and nutrient
recycling, high diversity in deadwood biocoenosis seems important to maintain
ecosystem processes. Previous research has mostly focused on a specific realm,
but cross-taxonomic research is necessary due to strong interactions between
saproxylic species. Otherwise, derived conservation methods focus on a small
subset of the occurring species diversity with potential negative effects on
other than the targeted species group.
This issue
is addressed in the joint research effort in the BELongDead experiment of the
Biodiversity Exploratories. Funded by the Deutsche Forschungsgemeinschaft
(German Research Foundation) I analyze data of saproxylic beetles, fungi and
bacteria via a diversity partitioning. With this analysis, it is possible to
detect the relevant scales for saproxylic biodiversity conservation and answer
the question: Does the mere presence of a deadwood stem, irrespective of tree
species, determine the presence and absence of most deadwood-depending species
or does it require a diverse array of deadwood tree species over a larger area?
Selected Research
R.J. Heim,
A. Bucharova, L. Brodt, J. Kamp, D.
Rieker, A.V. Soromotin, A. Yurteav, N. Hölzel (2020): Post-fire vegetation
succession in the Siberian subarctic tundra over 45 years, Science of the Total
Environment, DOI: 10.1016/j.scitotenv.2020.143425
Research
► Biodiversity
Exploratories
The Biodiversity
Exploratories are a large-scale and long-time biodiversity experimental set up,
funded by the German Research Foundation. In three climatically different
regions of Germany, the influence of management on the biodiversity of forests
and grassland is studied through a wide range of fields of research ranging
from microbes, herbs, and butterflies to deer and trees.
Multitrophic functional diversity in deadwood
► BELongDead
– Biodiversity Exploratories Long term Deadwood
In this experiment, 1140 logs of thirteen tree species (9 deciduous, 4 coniferous) were placed in different forest sites in 2009. On these logs, the biodiversity of beetles, fungi, bacteria, mosses, and lichens is studied and set into the context of molecular and biochemical mechanisms and processes of wood decomposition in relation to forest management practices and geographical scale. Besides assembly processes and succession of these organisms on different host species, their influence on decomposition rates and vice versa are examined.
► BESterile –
Biodiversity Exploratories Sterile
In a new setup,
72 logs from the two most abundant tree species in Germany Fagus sylvatica and Picea
abies will be exposed to gamma rays and placed beside the BElongDead experiment.
The sterilized logs will help clarify if differences in fungal diversity on
logs are caused by host tree characteristics or the endophyte communities.