Stand Browser - forestry in QGIS

I have for a long time used QGIS to store and view my forestry data. For almost as long time, I’ve been thinking about adapting QGIS to work better with forestry. There are mainly three areas I would like to improve:

  • Easy viewing of stand data
  • Caclulating stand data from observations
  • Yearly update of growth

This is the first step.

Data format

The plugin assumes the data is stored in a vector data set. The field names must follow the description below. It is modelled after how the Heureka data model of the SLU stores its data. See the Heureka Wiki for more info. Some filed names have been shortened, due to the 12 character limit of SHP-files.

The fields and their data shall be UTF-8 encoded.

Fält Typ Beskrivning
standid string Valfri identifierare, tex ‘12’
prodarea real Produktiv area [ha]
layer integer Beståndslager. Normalt = 1, överstandare/skärm = 2
meanage integer Genomsnittsålder
maturitycl string Huggningsklass Ex: ‘R1’ eller ‘S3’
sispecie string Art för ståndortsindex. Ex: G24 → ‘G’
sis integer Höjd för ståndortsindex. Ex: G24-> ‘24’
v integer Volym [m3sk/ha]
managecl string Målklass Ex: ‘PG eller ‘NO’
ppine string Andel tall i tiondelar Ex: ‘X’ = 10/10
pspruce string -”- gran -”-
pbroadleaf string -”- triviallöv -”-
pbirch string -”- björk -”-
pdeciduous string -”- ädellöv -”-
paspen string -”- asp -”-
poak string -”- ek -”-
pbeech string -”- bok -”-
pcontorta string -”- contorta -”-
plarch string -”- lärk -”-
dgv integer Medeldiameter, grundytevägd [cm]
comment string  
cai real Årlig tillväxt [m3sk/ha]
h real Medelhöjd [m]
n integer Stammantal [1/ha]
g real Grundyta [m2/ha]
invdate date Datum för senaste inventering
invsource string Källa senaste inventering (valfri text)
updated date Aktualitetsdatum (inventering, framskrivning, etc)
altitude integer Höjd över havet [m]
countycode integer DLÄN-kod. Se Heureka WIKI

Usage

In the drop-down menu at the top of the dock window, all available vector layers that contains the required standid field are shown. Select the layer you want to browse here.

Pushing the buttons Next and Prev shows information about the next and previous stand in the window. If any fields are missing in the vector layer, it is shown as blank. These buttons also change the current selection in the layer, and pans/zooms to the newly selected stand.

If you select - e.g. with the mouse or in the QGIS attribute table - more than one stand a new set of buttons appear. They are Next Selected and Prev Selected respectively. Pushing those buttons loops through the selected stands, but does not change the selection.

Next to the Stand ID field, there’s a field with yellow background and search icon next to it. Writing the name of a stand and hitting return or the search icon, searches for that stand and displays it. If no such stand is found, nothing happens.

Toolbox

By clicking the toolbox button, a new window is opened. It provuides the following functionality:

Grid

If you want to make a data set with inventory points for a stand, ‘Grid’ can distribute the points for you. By selecting a template layer file, you can also give the inventory points the fields you want. An example inventory template is provided.

The number of points is interpolated with a square root function between the minimum value for 1 hectare and the maximum value for 5 hectares. Above and below that size og stand, the number of points is fixed. The minimum distance between points is set to 25 m, and half that distance is used as padding to the stand border. If the number of points can not be randomly placed with those constraints within a certain time, the tool will give up and you will be notifed.

The ‘Grid’ tool scans the filed names and will look for a name indicating the field contains the id. If so, it will be populated with a sequence number.

If a field name indicates it contains a date, it will be populated with today’s date in ISO 8601 format (YYYY-MM-DD).

Example data

There is example data in the .../example_data directory.

It also contains a QML-file, that can be applied to the stand layer for a nice look.

A template file for inventory points is also provided. If you want to modify it, first copy it to a safe place.

Indices and tables