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Project 2 (phase II):

Connecting the green and the grey world - an experimental approach to separating climate, vegetation and geochemical effects on nutrient cycling along a climate gradient

 

Investigator Names and Contact Info::

  • Yvonne Oelmann (Geoecology-Biogeochemistry). Geoecology, Geography, University of Tuebingen, Germany
  • Katja Tielbörger (Plant Ecology). Plant Ecology Group, Institute of Evolution and Ecology, University of Tuebingen, Germany
  • Harald Neidhardt (Geoecology). Geoecology, Geography, University of Tuebingen, Germany

 

Chilean Collaborators Involved:

  • Lohengrin Cavieres (Ecology, Ecophysiology). Dept. Botánica, Universidad de Concepción, Chile
  • Felipe A. Aburto (Pedology, Biogeochemistry). Facultad de Ciencias Forestales, Universidad de Concepción, Chile

 

 

Postdoc:

Connecting the green and the grey world: an experimental approach to separating climate, vegetation, and geochemical effects on nutrient cycling along a climate gradient.

supervisor: Prof. K. Tielbörger, co-supervisor: Prof. Y. Oelmann

 

 

PhD:

Connecting the green and the grey world: an experimental approach to separating climate, vegetation, and geochemical effects on nutrient cycling along a climate gradient.

supervisor: Prof. Y. Oelmann, co-supervisors: Dr. H. Neidhardt, Prof. K. Tielbörger

 

MSc:

Export of nutrients from catchments along a climatic gradient in the Chilean Coastal Cordillera.

  • Lorenz Kandolf. University of Tübingen, Germany

supervisor: Prof. Y. Oelmann, co-supervisors: Dr. H. Neidhardt

 

MSc:

Nährstofflimitierung von Bodenmikroorganismen entlang eines Klimagradienten in Chile.

  • Katharina Huesmann. University of Tübingen, Germany

supervisor: Prof. Y. Oelmann, co-supervisors: Dr. H. Neidhardt

     

    BSc:

    Impact of climate and biota on the storage dynamics of sediment-associated organic carbon in river channels.

    • Paul Sandhaas. University of Tübingen, Germany

    supervisor: Prof. Y. Oelmann, co-supervisors: Dr. H. Neidhardt

    in cooperation with Dr. Thomas Hoffmann, project 6

     

     

    Project summary:

    One component why biota might shape the Earth’s surface is related to their active role as “weathering engine”. However, efficient nutrient cycling of both plants and soil microorganisms might reduce their need to access nutrients contained in bedrock especially under increasingly progressed weathering towards more humid climate. In addition, nutrient cycling is affected by even higher trophic levels i.e., herbivory. However, it is virtually unknown how climate, especially rainfall, interacts with herbivory in affecting nutrient cycling and litter decomposition. Our overall goal is to dissect the relative importance of biotic (plants, microorganisms, herbivores) and abiotic factors (geology, climate) on processes related to weathering and biogeochemical nutrient cycling. We will directly link biological and geochemical processes by a) doing in-depth studies on processes at the interface between the green, the brown, and the grey world that build on the foundations laid in Phase 1, and by b) doing integrated analyses of this data and of new data collected by a large interdisciplinary consortium collaborating in our drought experiment. We expand our initial focus on plant-soil-geology feedbacks related to litter both ‘downwards’ and ‘upwards’. Specifically, we will focus on a) nutrient limitation and nutrient efficiency of plants and soil microorganisms, and b) the influence of herbivory on decomposability of litter that both potentially affect biogeochemical rock weathering. To that end, we combine the EarthShape space-for-time approach with mechanistically orientated field experiments that manipulate climate conditions on-site. With this approach, we address the following overarching questions: Can spatial climate gradients, i.e. the result of long-term climatic impact on the earth surface, serve as proxy for short- to medium-term temporal climatic changes? Which processes (‘green vs. brown vs. grey’) can be best described by spatial gradients? We will be able to answer these questions based on observations and experiments in the field as well as plant and herbivory experiments in the greenhouse. To assess nutrient cycling, we will measure nutrients in plants, soil and soil microorganisms complemented by innovative stable isotope tracers. By addressing the explicit role of a whole suite of biota in nutrient cycling, we will reveal their potential role as “weathering engine” which is a backbone of EarthShape. Additionally, our study is the first in Chile to investigate climate change impacts on ecosystem processes using large field experiments. 

     

    Fig.: Conceptual model of the proposed work programme. Asterisks * indicate the central focus of Phase 1 with measurements that will be complemented in Phase 2. Dashed lines and the grey box show the tight connection to weathering processes, and thus the close integration into the EarthShape SPP.