SimForest Issues

I was attempting to run the SimForest simulation to find the number of tree species using the Zoar Valley Species Table, but I also encountered the same problems as Erin did, namely that this new species table is somehow incompatible with the equation list. Since the program does not run correctly when you modify the species table and the equation list at the same time, it will hamper our ability to track the number of trees of different species growing in Zoar Valley. 

I am also working to add the available light equation to my NetLogo program. This will use the leaf weight equation, which we have defined for the time being as being equal to 0.4 (the constant) * diameter of the tree.  

- Irena

I still cannot get Simforest to run all of our customizations at once. It will only cooperate with one or two at a time depending on what you want it to do. I emailed the creators of simforest and I was told that the project was no longer active and that they had no advice. This is very frustrating for me, I am not able to continue with my part of the project. I tried to add the number trees equation parameter to the original species table and then build the Zoar Valley species composition but it still won't work. I am going to have Irena try to run the new parameter with the zoar valley species table and see if it works for her. I am curious to see if it just my program or java not working correctly or if its an inherent problem with the program all together.

~Erin K. Pfeil

NetLogo Update

I've had some progress on the NetLogo model in that I finally have the trees growing to reflect their changing height and diameter. I am currently working on getting the user to insert their own tree species via a drop-down menu. This has been set up in the program, but a problem has been encountered in that the trees are currently only growing with the current values that the program was designed around. Now, the program must be able to work with a wide variety of species, so this is the last major issue that needs to be addressed. I think that this could be due to the fact that the available light equation is not reflecting the changing tree types, however, Erin is trying to address that by emailing a few of the people who worked on the SimForest project, and while some are no longer actively associated with it hopefully she can come across someone who will provide some info regarding the Botkin equations being used. 

After this (fairly major) issue has been addressed, all that remains will be to attempt to run the program with an eye to how it reflects the actual composition of Zoar Valley. 

Ok, I think I found a way to make it work. If you add the parameter and the equation to the original species table then change the species composition of the table it seems to work. I am going to print out the table that Dr. Lazar recently created and after adding the parameter "num trees" I will build the Zoar Valley species table. Cross your fingers everybody! I will post whether or not I am successfull later tonight.

~Erin K. Pfeil

Well Im still trying to get Simforest to work and produce usable data. After many hours over several days, I got it to accept the numbertrees equation into the Zoar Valley species composition table, but now the parameter won't actually do anything. Hey what a surprise. I will try to start all over again and see if it will work. It seems Simforest has serious issues allowing you to use more then one custom table at a time. If I use the new equation with the original tree list, it works fine and vise versa. When I try to use all of our custom stuff together it fails, several times its actually crashed the program. If anyone has any suggestions, let me know.

~Erin K. Pfeil

OK, I found some things that might be useful:

Ci = A constant of proportionallity relating leaf weight to tree diameter.

SLA = actually the leaf weight above tree n, the sum of the weight of the leaves on all trees taller then tree n.

soooo... when i get my simforest working again (which I optimistically am hoping is before our meeting today) i will see what equations they give in their equation list. I'm assuming that SLA depends on values provided from other equations, particularly one or ones that deal with leaf weight.

~Erin K. Pfeil

I have recieved the Forest Dynamics book from Ohiolink and found the equation for light availibility. Irena has put it into the following format with values I found in the book:

AL=1e^1(-(1/6000)*SLA)

The only issue at this moment is what value to give to SLA (Shading leaf weight). Three assumptions are given for the this variable:

1.) all of the leaf wieght is concentrated at a point at the top of a tree.
2.) therefore that all of the leaves of one tree shade any shroter tree and...
3.)... conversely, that none of the leaves of any shorter tree shade any leaf of a taller tree.

It states that SLA is leaf weight, which would differ from species to species, particularly as stated by Botkin, shaded tolerant and shade intolerant species. Earlier in the book its states that leaf wieght is the square of the diameter of the leaf, and an equations is given:

W=CD^2 (C is a constant with an i as subtext, which and what its value is, I dont know)

I am still working on getting my Simforest to work. My computer decided to bail on my over the weekend and I had to fix it and reinstall vista. Now I am in the process of finding a working download of Java 1.2 so that I can at least get Simforest up and running again, since it appears I no longer have that version of Java and the program won't open at all. Perhaps it will run correctly after I download Java again.

~Erin K. Pfeil

NetLogo Update

So far, the NetLogo model that we currently have plants one tree species. It has both birth, recruitment and death of the tree. The user can plant the tree anywhere using the cursor. There was a slight problem with recursion being too extreme in the program, as there were three equations (Growth, Maximum Potential Growth, and Diameter) which depended on each other and as a result couldn’t properly function when running at the same time. This was corrected. Now, the next goals we have for the model are:

                - Changing the size of the trees in the model to reflect their growth

                - Planting trees of different species

                - Adding graphs that reflect the changing state of certain tree variables

 

-- Irena

 

I have constructed a site table to reflect the affect of global warming on eastern hardwood forest, particularly Zoar Valley. I used data I found on this website:

http://www.epa.gov/climatechange/science/futurecc.html

I will make another that reflects a more extreme increase in temperature. This table shows the minimum predicted difference (1.8 degrees Celsius). There are no reliable predicted changes for rainfall, so I doubled it for every month. My guess is as good as any at the moment. I have also created a working excel notebook that contains tree table data from the historic site table and the global warming site table. I do not know what to really do with it at this time, until it can be broken up into more manageable pieces.

Once my Glass Box program is repaired (again) I will build the exact terraces I have data for as they exist. I feel this will offer an even more realistic simulation.

I have also ordered a book (Forest Dynamics: An ecological Model, by Botkin) through Ohio Link that Irena found, it should be very useful.


~Erin K. Pfeil

NetLogo Model Progress

I have been working on some of the issues with the NetLogo model and made the following changes:

 - the waterstress variable has been changed to 0.1 to produce a high enough value in the sitequality equation to ensure that trees are being recruited. 

- availablelight has been changed to 0.99 (from 0.74), which now allows recruitment to proceed as well

With these variables, trees are now both dying and being recruited. 

Next on the list is working on height, diameter and age. I am working towards having the entire model based on "ticks", which is simply a different method of representing the passage of time - the model changes after a certain discrete amount of time (one "tick") rather than continuously. This could help reflect the way that a change in a tree is shown after every whole year, the way it is in other models. 

Irena