Projects
Modeling forest diversity in response to management and herbivory and the consequences for long-term carbon dynamics
Scientist(s): Frederic Holzwarth (PhD), Christian Wirth (PI)
Technical staff: Dorothea Frank, Anja Fankhänel
Funding: DFG, Task 3 within the joint project "Towards a mechanistic understanding of biodiversity and its functional consequences - The Biodiversity Exploratory additional modeling component (BEAM)" (WI 2045/5-1)
Duration: 2008-2010
Project description:
General overview BEAM: We propose to develop, test and apply complementary modeling tools that set an intellectual framework to better understand the causes and drivers of biodiversity and their consequences for ecosystem processes and functioning (functional biodiversity research). The overall goal is to test and elucidate the main processes behind three central hypotheses underpinning the experiments of the "Biodiversity Exploratories" initiative that was recently started in Germany. These hypotheses fall into three groups: (A) Diversity is positively correlated across taxa and levels; (B) Along land use gradients the biodiversity of different taxa and levels (genetic, species, interactions) changes in similar ways; (C) Higher biodiversity improves ecosystem functioning. The proposed models progress from theoretical models addressing general questions concerning the emergence of diversity patterns at the landscape level to more data-oriented models that specifically apply to the two major habitats (grassland, forest) investigated in all three Exploratories. All model approaches will explicitly address the link between biodiversity and ecosystem functioning, e.g. resilience, stability, productivity, carbon sequestration, decomposition, water use, pollination. These models are intended as first steps towards a mechanistic understanding of the factors determining biodiversity and its link to ecosystem functioning at the Biodiversity Exploratories. Beyond the integration of the five models, we intend to play an active role within the overall Biodiversity Exploratories project and provide a platform for integrating the German modeling community by organizing a series of disciplinary and interdisciplinary workshops.
Task 3:The overall goal of Task 3 is to develop a modeling framework that allows a better understanding of the causes and drivers of tree diversity and their consequences for carbon, water and energy exchange in temperate forests. Different models and modeling strategies will be combined to address a range of hypotheses within set B ("understanding the role of land use for biodiversity", B.1) and set C ("understanding the role of biodiversity for ecosystem processes", C.1, C.2, C.4, C.5, C.7, and C.11) of the Biodiversity Exploratory project. The initial step is to use the full suit of inventory data available for the Biodiversity Exploratories to either directly or inversely parameterize the core functions of a demographic model. This will allow us to project and analyze succession under different management regimes and levels of herbivory (subtask 3.1). The emergent patterns of species-, functional and structural diversity will be translated into ecosystem functions such as gross and net primary production, soil carbon accumulation and evapotranspiration. To this end, the demographic model will be coupled to two different ecosystem models reflecting different processes and time-scales (a pool-based soil and vegetation carbon model with an annual time-step in subtask 3.1 and an ecophysiological soil-vegetation-atmosphere model with an hourly time-step in subtask 3.3). This sequential strategy allows us to explore the consequences of correlations between demographic and functional traits ("cross-categorical trait correlations" - see 2.1.3 and hypothesis C.9). Under subtask 3.4 the parameterization and validation strategy will be outlined.
This task is designed for two PhD projects and will deliver (a) a succession model designed to assimilate a large part of the forest inventory data of the Biodiversity Exploratories, (b) a characterization of the diversity of the potential natural forest composition, (c) a quantification of the effect of management and browsing on forest diversity, (d) new insights into diversity-functioning relationships by means of a novel approach of cross-categorial trait analysis, (e) characterization of indirect effects of management on long-term carbon cycling, and (f) a biophysical and ecophysiological interpretation of diversity-functioning relations in forests diversity
Partners:
Within BEAM: Kerstin Wiegand (Universität Jena), Thomas Hovestadt (Universität Würzburg), Florian Jeltsch (Universität Potsdam) und Markus Reichstein (MPI für Biogeochemie)
External Partners: Markus Fischer (Universität Bern), Jürgen Bauhus (Universität Freiburg), Christoph Leuschner (Universität Göttingen), Drew Purves (Microsoft Research Cambridge), Jürgen Vosshage (Thüringer Landesanstalt für Wald, Jagd und Fischerei), Tanguy Daufresne (INRA, Castanet-Tolosane, France), Michael Scherer-Lorenzen (ETH Zürich)