Applications: RegWise

 

You can let RegWise simulate large scale storm fellings based on user defined wind scenarios. A wind scenarios contains information when and where storms will occur, and the wind load of each storm.

 

Model description

The model to calculate risk of storm felling is described here (Lagergren et al) https://www.heurekaslu.se/wiki/File:Stormskador_i_Heureka.pdf

 

Settings

Settings for storm fellings are made in control table Scenario Settings (RegWise only), in sektion Wind Damage:

 

 

Use Wind Damage Model: Set this parameter to True to include storm fellings in a simulation.

 

Probability for Final Felling*: Probability that a stand is so severely damaged by a storm that final felling and regeneration is required. Refers to proportion of total forest area damaged by a storm. The default value (0.64) is based on the report "Analys av stormskador efter Gudrun" by Fridman et al (2006) (http://www.slu.se/PageFiles/33707/2006/FS06-08.pdf).

 

Windthrow Proportion Other Stands: The proportion of stand's basal area that is damaged by a storm less severely than a stand that must be regenerated. Wind-thrown trees are extracted by simulating a thinning, if not left as dead wood. The thinning grade depends on how many of the wind-thrown trees that are extracted or left as dead wood, respectively (see Dead Wood Proportion of Windthrown Trees below). Example: If Windthrow Proportion is 35 %, and Dead Wood Proportion of Windthrown Trees is 50 %, then a thinning is applied with thinning grade 17.5 %. A thinning is done as a uniform thinning - once a storm felling has occurred all trees trees in a stand are assumed to be damaged to the same degree. However, the selection of stands that are damaged takes into account each tree's species, height and diameter (see the model document for details).

 

Dead Wood Proportion of Windthrown Trees: Proportion of wind-thrown trees that are no extracted but left as dead wood.

 

Storm Exposure Data: Contains data that describes landscape fragmentation and average stand size at a county level.

 

Storm Scenario Parameters: Table with parameters for which time periods storms should occur, and the wind load in each storm. The table also contains assumed mean height of trees (HgvCounty) in each county (!) which is used as a variable in the storm felling model. The reason for not letting Heureka calculate these mean heights is that a simulation is not necessarily done for a whole county.

 

 

Storm Exposure Data and Storm Scenario Parameters can be imported from text files (csv-files) by clicking on the "Load from file.."-button (see figure above).

 

Increased harvesting costs

Starting from version 2.12, you can let the program account for increased harvesting costs in storm-felled stands. In the Cost and Revenues control table, in section Storm Felling Time Consumption Adjustment. Here you can enter time adjustment factors for the time consumption in harvesting and forwarding in final felling and thinning. For example, a factor of 1.5 means a 50% increase. For selection felling, the same factors as for thinning are used.

 

 

 

Limitations:

Possible price reductions on timber and pulpwood as well as increased harvesting costs are not handled today (Nov 2014).