The Earth's ecosystems range from highly productive tropical rainforests around the equator to the barren tundra in the far north. But even one and the same ecosystem can look very different, for example a very young forest with many pioneer plants (after a disturbance event) compared to an old forest with few, large trees. In addition, in most regions of the world, humans have noticeably changed the landscape, for example by clearing forest for agriculture and livestock breeding or by planting foreign tree species for economic use. The complexity of these processes can only be represented in a simplified way in computer models.
LPJ-GUESS is a process-based dynamic global vegetation model simulating vegetation dynamics and composition in response to changes in climate, atmospheric CO2 concentration, nitrogen deposition and land-management at local to global scale (Smith et al., 2014).
The Earth's surface is divided into a grid, with the size of each grid-cell depending on the total simulated area and the resolution of the available input data (usually 0.5° x 0.5°). Grid-cells are often further subdivided (e.g. one part of the grid cell is covered by forests while the rest is used for agriculture), but the environmental conditions (e.g. climate) are the same everywhere within the grid-cell. in the standard LPJ-GUESS version, different plant species are combined to a number of so-called plant functional types which differ in their growth strategies and climatic preferences (e.g. beech and oak are both represented by the temperate broad-leaved deciduous plant functional type). While in many other dynamic vegetation models only one single average tree is calculated per grid-cell and plant function type, LPJ-GUESS simulates different age classes. This allows for a more realistic representation of interactions and competition. For example, young trees may die when the canopy closes and thus not enough light reaches the layers close to the ground. Mortality also results from a limited supply of resources in the soil (e.g. water), when the maximum life span of a tree is reached, when certain temperature limits are exceeded, or due to disturbances.. The dead biomass goes into the soil where it is gradually decomposed. Subsequently, a slow regrowth of vegetation occurs in the form of a succession from shade-intolerant to shade-tolerant plant function types. Besides forest ecosystems, LPJ-GUESS also allows for the simulation of pastures and crop functional types and their management (Lindeskog et al., 2013).
Selected LPJ-GUESS related publications from our group
Krause A, Knoke T, Rammig A (2020). A regional assessment of land-based carbon mitigation potentials: bioenergy, BECCS, reforestation, and forest management. Global Change Biology Bioenergy. 12: 346-360.
Krause A, Haverd V, Poulter B, Anthoni P, Quesada B, Rammig A, Arneth A (2019). Multimodel Analysis of Future Land Use and Climate Change Impacts on Ecosystem Functioning. Earth's Future 7, 833-851.
Fleischer K, Rammig A, DeKauwe M, Walker A, Domingues T, Fuchslueger L, Garcia S, Goll D, Grandis A, Jiang M, Haverd V, Hofhansl F, Holm J, Kruijt B, Leung F, Medlyn BE, Mercado L, Norby R, Pak B, Quesada CA, von Randow C, Schaap K, Valverde-Barrantes OJ, Wang Y-P, Yang X, Zaehle S, Zhu Q, Lapola D (2019). Future CO2 fertilization of the Amazon forest hinges on plant phosphorus use and acquisition. Nature Geoscience 12, 736-741.
Rammig A, Jönsson AM, Hickler T, Smith B, Bärring L, Sykes MT (2010).
Impacts of changing frost regimes on Swedish forests: Incorporating cold hardiness in a regional ecosystem model. Ecological Modelling 221 (2):