Impact model: 3PG-Hydro

Sector
Forests
Region
local

3PG-Hydro is an upgraded version of the process-based model 3-PG (Landsberg and Waring, 1997) that was developed to represent important hydrological processes. The update integrates a soil model and calculates in daily time steps.

Information for the model 3PG-Hydro is provided for the simulation rounds shown in the tabs below. Click on the appropriate tab to get the information for the simulation round you are interested in.

Person responsible for model simulations in this simulation round
Marc Djahangard: marc.djahangard@ife.uni-freiburg.de, 0000-0001-9550-6343, Universität Freiburg (Germany)
Additional persons involved: rasoul.yousefpour@ife.uni-freiburg.de
Basic information
Model Version: 1.1
Model Homepage: https://github.com/mdjahan/3PGHydro
Model License: use on request (GPL-3.0 license)
Reference Paper: Main Reference: Yousefpour, Rasoul & Djahangard, Marc et al. Simulating the effects of thinning events on forest growth and water services asks for daily analysis of underlying processes. Forests,12,,2021
Resolution
Spatial aggregation: forest stand
Vertically resolved: No
Temporal resolution of input data: climate variables: daily
Temporal resolution of input data: co2: annual
Temporal resolution of input data: soil: constant
Input data
Observed atmospheric climate data sets used: W5E5v1.0
Climate variables: tasmax, tasmin, rsds, pr
Spin-up
Was a spin-up performed?: No
Natural Vegetation
Soil layers: Two soil layers: effective root zone & deep root zone, water flow is simulated as 1-D vertical flow.
Management & Adaptation Measures
Management: By thinning
Model set-up specifications
How did you initialize your model, e.g. using individual tree dbh and height or stand basal area? how do you initialize soil conditions?: Tree number and total tree biomass per stand derived from average DBH
Which data from profound db did you use for initialisation (name of variable, which year)? from stand data or from individual tree data?: Stand data: average DBH, stem number, soil characteristics
How is management implemented? e.g. do you harvest biomass/basal area proportions or by tree numbers or dimensions (target dbh)?: By number of trees removde and thinning regime: from below, middle, above. Depending on the selection lower or higher amount of biomass is extracted.
When is harvesting simulated by your model (start/middle/end of the year, i.e., before or after the growing season)?: Start of the year
How do you regenerate? do you plant seedlings one year after harvest or several years of gap and then plant larger saplings?: No regeneration
How are the unmanaged simulations designed? is there some kind of regrowth/regeneration or are the existing trees just growing older and older?: No regrowth or regeneration but self-thinning mortality is included reducing the stem number.
Does your model consider leap-years or a 365 calendar only? or any other calendar?: Leap-years
What is the soil depth you assumed for each site and how many soil layers (including their depths) do you assume in each site? please upload a list of the soil depth and soil layers your model assumes for each site as an attachment (section 7).: 2 layers for each site. Upper layer (0.5 - 1m), lower layer (3m).
Is there any stochastic element in your model (e.g. in the management or mortality submodel) that will lead to slightly different results if the model is re-run, even though all drivers etc. remain the same?: No
What is the minimum diameter at which a „tree is considered a tree“? and is there a similar threshold for the minimum harvestable diameter?: 1 cm
Has your model been "historically calibrated" to any of the sites you simulated? e.g. has the site been used for model testing during model development?: No
Key model processes
Dynamic vegetation: Yes, forest growth and management
Nitrogen limitation: No
Co2 effects: Yes
Light interception: Yes
Light utilization: Yes
Phenology: Yes, only for deciduous trees start of the growing season calculated by the growing-degree-days with average temperature exceeding threshold. Ends in october.
Water stress: Yes, photosynthesis is reduced if water demand is greater than water supply and by the water content of the upper soil layer.
Heat stress: Yes, photosynthesis is reduced if temperature exceeds a maximum threshold.
Evapo-transpiration approach: Yes, calculated with Penman-Monteith equation. Seperatly: Interception water evaporation, stand transpiration & soil evaporation.
Differences in rooting depth: No
Root distribution over depth: No
Closed energy balance: No
Coupling/feedback between soil moisture and surface temperature: No
Regeneration/planting: No
Soil water balance: Yes
Causes of mortality in vegetation models
Age/senescence: Yes
Fire: No
Drought: No
Insects: No
Storm: No
Stochastic random disturbance: No
Other: Self-thinning depending on stand density
NBP components
Harvest: Harvest is included: all fluxed affected.
Model output specifications
Do you provide the initial state in your simulation outputs (i.e., at year 0; before the simulation starts)?: Yes, first day of output is initial state.
Output format: Daily, stand scale
When you report a variable as "xxx-total" does it equal the (sum of) "xxx-species" value(s)? or are there confounding factors such as ground/herbaceous vegetation contributing to the "total" in your model?: Accounts only to species, no confounding factors
Did you report any output per dbh-class? if yes, which variables?: No
Additional Forest Information
Forest sites simulated: Bily kriz, Collelongo, Solling