The spatial distribution of tree-tree interaction effects on
soil microbial biomass and respiration
Henriette Christel1,2, Helge
Bruelheide1,3, Simone Cesarz1,2,
Nico Eisenhauer1,2, Georg J. A.
Hähn4, and Rémy Beugnon1,5,6
Institutions:
1 German Center for Integrative Biodiversity Research
(iDiv) Halle-Jena-Leipzig, Puschstrasse 4, 04103 Leipzig, Germany
2 Institute of Biology, Leipzig University,
Puschstrasse 4, 04103 Leipzig, Germany
3 Institute of Biology/Geobotany and Botanical Garden,
Martin Luther University Halle-Wittenberg, Am Kirchtor 1, 06108 Halle,
Germany
4 BIOME Lab, Department of Biological, Geological and
Environmental Sciences (BiGeA), Alma Mater Studiorum University of
Bologna, Via Irnerio 42, 40126, Bologna, Italy
5 Institute for Meteorology, Leipzig University,
Stephanstraße 3, 04103 Leipzig, Germany
6 CEFE, Univ Montpellier, CNRS, EPHE, IRD, 1919, route
de Mende, F-34293 Montpellier Cedex 5, France
Corresponding author: Henriette Christel, Puschstrasse 4, 04103 Leipzig,
Germany,
henriette.christel@idiv.de
Abstract
The capacity of forests to sequester carbon in both above- and
belowground compartments is a crucial tool to mitigate rising
atmospheric carbon concentrations. Belowground carbon storage in forests
is strongly linked to soil microbial communities that are the key
drivers of soil heterotrophic respiration, organic matter decomposition,
and thus nutrient cycling. However, the relationships between tree
diversity and soil microbial properties such as biomass and respiration
remain unclear with inconsistent findings among studies. It is unknown
so far how the spatial configuration and soil depth affects the
relationship of tree richness and microbial properties.
Here, we studied the spatial distribution of soil microbial properties
in the context of a tree diversity experiment by measuring soil
microbial biomass and respiration in subtropical forests (BEF-China
experiment). We sampled soil cores at two depths at five locations along
a spatial transect between the trees in mono- and heterospecific tree
pairs of the native deciduous species Liquidambar formosana andSapindus saponaria .
Our analyses showed decreasing soil microbial biomass and respiration
with increasing soil depth and distance from the tree in monospecific
tree pairs. We calculated belowground overyielding of soil microbial
biomass and respiration - which is a higher microbial biomass or
respiration than expected from the monocultures - and analysed the
distribution patterns along the transect. We found no general
overyielding across all sampling positions and depths. Yet, we
encountered a spatial pattern of microbial overyielding with a
significant microbial overyielding close to L. formosana trees
and microbial underyielding close to S. saponaria trees. We found
similar spatial patterns across microbial properties and depths that
only differed in their effect size.
Our results highlight the importance of small-scale variations of
tree-tree interaction effects on soil microbial communities and
functions and are calling for better integration of within-plot
variability to understand biodiversity-ecosystem functioning
relationships.
Key words: belowground overyielding, soil microbial biomass, tree-tree
interaction, Biodiversity-Ecosystem Functioning