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SVD

Scaling Vegetation Dynamics

 

 

SVD

The SVD framework is a deep-learning based modeling framework for upscaling vegetation transitions. iLand is particularly well suited to provide training data for the deep neural networks and ecosystem attribute data. The model already includes the means to classify vegetaiton into distinct "states" that are used in SVD and direct outputs to generate attribute information.
The spatial grain for SVD related data is the resource unit level, i.e. 1ha.

Definition of states

iLand can
The section model.settings.svdStates in the project file is dedicated to the definition of states in iLand.

KeyTypeDescription
enabledbooleanif true iLand tracks the vegetation state for each resource unit over time.
structurestringtype of classification scheme for structure (i.e. canopy height). See below for details.
functioningstringtype of classification scheme for ecosystem functioning (i.e. canopy height). See below for details.

The classification of structure

The structure component is related to the canopy height on a resource unit; we here use the "top height" which we define as the 90th percentile of the the maximum tree height on the 10m "height grid".
A canopy is irregular when the height on 50% of the area (10m pixels) is below the top height

The following types are available (key structure):

  • 4m: classes with a width of 4m (0- <4m, 4- <8m, 8 - <12m, ...) and a maximum height of 80m. For irregular canopies the class width is 12m (<12, 12- <24, ... 48- <60m, >=60m). The total number of classes is 27 (21 standard, 6 irregular)
  • 2m: classes with a width of 2m and a maximum top height of 60m (0 - <2m, 2 - <4m, .... 58 - <60m, >60m ). For irregular canopies the class width 8m (<8m, 8 - <16m, 48- <56m, >=56m). The total number of classes is 39 (31 standard, 8 irregular)

The classification of functioning

Ecosystem functioning is based on the leaf area index of a resource unit. The leaf area index includes both adult trees (height >4m) and saplings (<4m).
The following schemes are available (key functioning):

  • 3: three classes: LAI 0 - <2, 2 - <4, >=4
  • 5: five classes LAI 0- <1, 1- <2, 2- <3, 3- <4, >=4


Compact GPP potential per RU

Table Name: svdgpp
GPP potential (as conditioned by climate/site) per species and m2.

captiondatatypedescription
yearintegersimulation year
ruintegerindex of ressource unit
ridintegerid of ressource unit (-1: no ids set)
climate_yearintegeryear of the climate table
gpp_s1doublegpp of species 1
gpp_s2doublegpp of species 2
gpp_s3doublegpp of species 3
gpp_s4doublegpp of species 4
gpp_s5doublegpp of species 5
gpp_s6doublegpp of species 6
gpp_s7doublegpp of species 7
gpp_s8doublegpp of species 8
gpp_s9doublegpp of species 9
gpp_s10doublegpp of species 10


Forest state transitions

Table Name: svdstate
Forest state (for SVD). The output contains fixed columns (see below) and adds two extra columns for every active tree species. Those species columns hold the species share 0..1 for the local and the mid-range-neighborhood. Former have 'l_' and latter 'm_' as prefix (e.g. 'l_piab', 'm_piab'). Note that the sum of all shares is <=1, but can be lower than 1. See also the 'svduniquestate' output.

captiondatatypedescription
yearintegersimulation year
ruintegerindex of ressource unit
ridintegerid of ressource unit (-1: no ids set)
stateIdintegerunique state Id within one iLand simulation
previousStateIdintegerunique state Id that the RU was before the current state
previousTimeintegernumber of years that the resource unit was in the previous state
l_piabdouble
m_piabdouble
...double


SVD forest indicator data

Table Name: svdindicator
Indicator data per resource unit as used by SVD.
The selection of indicators is triggered by keys in the project file (sub section 'indicators'). The following columns are supported:

keydescription
shannonIndexshannon index (exponential) on the RU (based on basal area of trees >4m)
abovegroundCarbonliving aboveground carbon (tC/ha) on the RU (trees + regen)
totalCarbonall C on the RU (tC/ha), including soil, lying and standing deadwood
volumetree volume (trees>4m) m3/ha
crownCoverfraction of crown cover (0..1) (see saveCrownCoverGrid() in SpatialAnalysis - not yet implemented)


An example for the project file node:
<indicators>
<shannonIndex>true</shannonIndex>
<abovegroundCarbon></abovegroundCarbon> ...
</indicators>

captiondatatypedescription
yearintegersimulation year
ruintegerindex of ressource unit
ridintegerid of ressource unit (-1: no ids set)
stateIdintegercurrent state of the resource unit (see 'svdstate' output)
timeintegernumber of years the resource unit is already in the state 'stateId' (see 'svdstate' output)


Unique forest states

Table Name: svduniquestate
List of forest states for the current simulation (for SVD). Each state is defined by a unique numerical Id ('stateId') which is used as a key in the 'svdstate' output.

captiondatatypedescription
stateIdintegerunique state Id within one iLand simulation
compositionstringspecies composition state
structureintegerdominant height class (class index)
functioningintegerleaf area index (class index)
descriptionstringVerbose description of the state

Created by werner. Last Modification: Friday 07 of December, 2018 08:42:08 CET by werner.