Ecophysiological forest stand modelling with XL/Java and GroIMP via internet

Institute of Forest Biometry and Informatics

Georg-August-University Göttingen

Ecophysiological foreststand modelling with XL/Java and

GroIMP via internet

Dirk Lanwert

Institut of Forest Biometry and Informatics

Göttingen 2007



Today: two aspects?

Ecophysiological forest stand model

1. which method and scale uses the model

2. how to use the growth model as via internet

dirk lanwertSlide 2



1. Aspect

Method and scale of the model



Triangle of plant models

dirk lanwert

Base relationship between: Structure<-> Process -> core business of FSPM

Scale: higher aggegration

Where we can find classical forest yield models?

Quelle: Buck-Sorlin, Kurth

Slide 4



Forester’s Aim

dirk lanwert

how to include spatial information in forest yield models

without increasing to much

complexity

computing time

demand on underlying information

Short: how to intergrate reasonable the competition between individual trees within a stand in tree growth prediction

Quelle: Kurth

Slide 5



Eccophysiological models

dirk lanwert

: clasical position of FSPM-models

are a way to occupy the upper part of the model triangle for the use in forest practice.

Slide 6



Our proposal:

1. a ecophysiological forest stand model with individual trees

2. the estimation of light conditions within the stand using needle the biomass distribution (competition)

3. the calculation of the photosynthesis production efficiency using a relation between:– unshaded condition and shaded condition

(biomass as independent variable)

dirk lanwert

method from Sloboda & Pfreundt 1989

Slide 7



Stand data requirements

dirk lanwert

initial data requirements:► spatial stem parameter:

– position, d1.3, height,

► spatial crown parameter:– position, height, diameter

Slide 8



Model calculation cycle

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biomass

Slide 9



Structure: main features

► a tree consists of vertical segments► each segment owns his needle

mass (beta distribution)► segments are the calculation units

dirk lanwert

needle mass per segment

Slide 10



shading needle biomass

► calculated is all needle mass inside a cone of 60°

► divided by squared distance of the owner segment

dirk lanwertSlide 11



relative photosynthetic production

► maximum production rate = unshaded conditions above the tree top

► shading needle biomass within the cone as independant variable of a reduction function

dirk lanwert

)())(( xBkeaxBF

Slide 12



Why it is a good idea to use XL and GroIMP

1 private void kalkuliereExterneBeschattung(float winkel)

2 {

3 [

4 s:Segment -ancestor-> best:Bestand,

5 ( s.nadelMasseGesamt > 0.0f && best.aktiv == true) ::>

6 {

7 s.externeBeschattung = 0.0f;

8 // Ermitteln der beschattenden Segmente(a) für das aktuelle Segment (s)

9 for ((* b:Baum (-->)* a:Segment ,

10 ( s.getParent() != b && b.getLastChild() in cone(s, false, winkel)),

11 ( a.nadelMasseGesamt > 0.0f && a in cone(s, false, winkel)) *))

12 {

13 s[externeBeschattung] += ( a.nadelMasseGesamt

14 * b.lichtTransmissionsKoeffizient / (distanceSquared(a, s)

15 + b.kalkuliereNadelMasseVerteilungKorrekturTerm()));

16 };

17 if (s.externeBeschattung > 0.0f) s[color] = F_BESCHATTET;

18 }

19.]

20}




2. Aspect

Internet Connection



The idea:

1. the model should be accessible remotly via http

2. necessary stand description data can be included as http-post multipart/formdata.

3. calculation results will be stored in a file

4. the result file will delivered on demand via http-get

dirk lanwert

Short: the model as a web-service

Slide 15



The solution

Generalised stand desctiption(Forester stand description: VRML Format)

sending program( http, http-post)

(multipart/formdata)

dirk lanwert

ModellGroIMPCaller

build in web-server (part of GroIMP)

conecting the web-server (XL/Java class, input/output methods)

understanding multipart/formdata(httpform package)

understanding forester stand description (forester package)

using tree data(model code)

Slide 16



Easy integration of the web-server

import de.grogra.imp.net.*

…

protected void startup()

// Startmethode für den HTTP-Server-Betrieb.

{

super.startup();

HttpResponse resp = HttpResponse.get(workbench());

if (resp != null)

{

runLater(resp);

}

}

protected void run (Object info) {

HttpResponse resp = (HttpResponse) info; //object with all recieved data

StringBuffer buf = new StringBuffer(); // textbuffer for the answer

buf.append("url=" + server + "/open?" + modelout + ";" + filename + "\n"); // write answer

resp.setContent("text/text", "UTF-8", buf.toString()); //answer format

resp.send(true); //send answer

init(); // start model

closeWorkbench();

}




Easy integration of the web-server

protected void run (Object info)

{

…

// Read the form-data

HttpMultipartFormData n1 = httpstartup.verarbeiteHttpInput(info);

// Read Forester-Description

foresterDescriptionIn = httpstartup.readForesterDescriptionFormfield(n1);

// Create and send answer

String filename = httpstartup.createAnswer(info,n1,foresterDescriptionIn);

init(); // initialise model

if(foresterDescriptionIn != null){

// specific part: start

ersterSchritt(); // construct stand

for (apply (simulationsPeriode)) kompletterJahresDurchlauf(); // run one year periode

abspeichern(foresterDescriptionIn , ( modelOutputDir + filename) );

//specific part: end

}

closeWorkbench();

}




Step 1: send the vrml file

dirk lanwert

http://ufgb985.forst.uni-goettingen.de:5880/open?lichtmodel.gsz

Slide 19



Step 2: Model calculation with GroIMP

dirk lanwert

stored in file:bestand_100230049033 stored in file:bestand_100230061119

Slide 20



Step 3: deliver vrml file with resulting stand

dirk lanwert

http://ufgb985.forst.uni-goettingen.de:5880/open?deliverscene.gs

scene=bestand_100230049033 scene=bestand_00230061119

Slide 21



Thank you for your attention

and Ole Kniemeyer for GroIMP

Documents

Ecophysiological forest stand modelling with XL/Java and GroIMP via internet