RESPECT's general research concept is based on previous work which helped to define a-priori Plant Functional Types (PFT). First, traits and abiotic covariates are collected on joint core plots. This data is used for a statistical analysis in a Response-Effect Framework (REF) and for the parameterization, operation and evaluation of a Land Surface Model (LSM). Scenarios on future climate change are derived to force the LSM to test RESPECT’s central hypotheses.
The LSM approach consists of three coupled submodels that simulate biological processes (LPJ-GUESS), hydrological fluxes (CMF) and atmospheric fluxes (CLM). Mean exchange variables are soil moisture from LSMHydro to the other submodels and vegetation development (LAI) from LSMBio to the other submodels. The central hypotheses will be tested for the two ecosystem functions simulated by the coupled LSM under different environmental preconditions and scenarios.
To answer the RESEPCT research questions, LSM runs on the plots will be forced with present day conditions (undisturbed) and under disturbances (e.g. climate change). It is expected that mean ecosystem functions (TF) will be significantly reduced under disturbance regimes concomitant with a reduction in the mean trait values. Because the model considers trait diversity for all PFTs forming the community, the distribution of the TF effect traits will be narrowed after a disturbance, reducing trait diversity (see frequency distributions in the figure). The dotted line depicts the resulting mean trait value.
The REF approach will make use of a set of statistical methods, i.e. multiple regressions, structural equation models, simulation models to integrate all data into a common synthesis, based on the level of the community (PFT and plot level).
The REF approach is the complementary to the LSM approach by providing combined insights into the relationships between functional trait diversity and ecosystem processes and functioning as further impulses for the LSM (Note that R means response and E effect)
With the REF approach we:
(i) explore the change of trait metrics with elevation and land use.
(ii) estimate the overall response of the trait and process data to environmental changes from the differences between the response and effect trait diversity of the taxa and PFTs.
(iii) evaluate the effects of changes in the trait composition on the associated ecosystem process.