Forest-BGC System Summary

January, 1989

Steven W. Running

University of Montana

Two input files are needed to execute a simulation:

1) A climate file, named "filename.CLM". See code in DC_ZCOMP for

required input data format.

2) A header file which includes site parameters and constants, and

input-output processor control. It is named "filename.DAT"

Two optional files allow any of the input B variables to change

automatically with a specified year day or year number of simulation.

These files are:

3) filename.SEA Changes specified B variables seasonally by year

day

4) filename.LIF Changes specified B variables by year number

A 0/1 flag in the header file allows you to activate these files during

simulation. The .SEA and .LIF files are simple ASCII files like the

ones given in this demo as JAC84.SEA, which as an example changes B[11]

to 20.0 and B[18] to 1.0 on yearday 10, and JAC84.LIF, which changes B[30]

to 0.17 in year 3 and B[21] to 0.0004 in year 5. You may include as many

rows and columns as necessary, but all empty spaces should be occupied by

a * in the matrix. The file should have the same filename as the header

file, but with the extension .SEA for changes on a specific yearday, or

.LIF for change beginning with a particular year.

Three output files are possible:

1) "Filename.DAY" provides daily figures for: soil water; outflow;

evaporation; transpiration; water potential; photosynthesis;

and maintenance resp.

2) "Filename.GRW" provides annual figures for: transpiration;

photosynthesis; maintenance resp.; and leaf, stem, and root

carbon.

3) "Filename.LNG" provides detailed annual output of any variable

specified in the header file.

The user specifies the desired output file(s) in the header file. An

example of each is included for reference. The .DAY file was run for

one year with KPRINT = 1 (daily). The .GRW and .LNG files were run for

twenty years with KPRINT = 365 (yearly). Notice that the first two lines

in the .DAT files are reserved for comments, which are printed at the top

of the corresponding output files.

*Note: Although the header file contains 20 X variables, this portion of

the model is not fully developed, and only the first ten are used. In

this version, new canopy growth is assumed to equal canopy litterfall,

holding total leaf carbon constant.

The program files are:

SIMLAT5.PAS This is the main program and simulation processor,

written in Turbo Pascal. Its compilation and execution

encompasses the following files.

DC_DAY.PAS Code for daily water balance, photosynthesis, and

maintenance respiration

DC_YEAR.PAS Annual growth, respiration, and litterfall

DC_ZCOMP.PAS Reads climatic data and derives all climatic

variables

DC_FUNC.PAS Contains Penman-Monteith and miscellaneous functions

DC_DATA.PAS Global data and constants

DC_PRN.PAS Short file output specification

SIMLAT5.EXE Complete, compiled program in Turbo Pascal, ready to

run on an IBM PC/XT/AT/PS-2

This is logically one program. It has been separated into individual

files for clarity and easier text editing. Most compilers can include

code from other files during the compilation process, emulating a

monolithic program file.

The source code is documented to provide descriptions of system

functions and simulation processes. Read DC_ZCOMP.PAS for climatic

data inputs.

To recompile in Turbo Pascal, bring SIMLAT5.PAS into the work file area

and compile. SIMLAT5.PAS automatically couples the above files for

compilation. The .CLM and .DAT file are needed only for execution.

To run the model initially, just type SIMLAT5, and the SIMLAT5.EXE file

will begin. You will be prompted to enter the filename for the current

run. This demo includes two test files, one for Jacksonville, FL, the

other for Missoula, MT. These two sites were chosen for demonstration

because of their dramatically different climatic regimes. Depending on

which site you'd like to run, answer the prompt with either JAC84 or

MISS84, with no extension. The appropriate header and climate files

are then used in execution. The output files you've specified are

automatically written to the same disk as the header file.

Also included in the main directory is a file called DAY.WQ1. This

option allows you to examine .DAY output via four custom QUATTRO graphs.

You must have QUATTRO PRO available to utilize this option. In QUATTRO,

retrieve the DAY.WQ1 worksheet and go to the top of the worksheet. Replace

the sample directory to where you have loaded your FOREST-BGC demo, and the

filename to JAC84.DAY (unless you have already created a MISS84.DAY - you

may then use that one). Press Alt-D for the menu. Pressing L will then load

the .DAY file you have specified. Then simply choose the graph option that

you wish from the menu, using Esc to get back to the graph menu.

This demo disk also contains a subdirectory called MTCLIM that explains the

mountain microclimate simulator used in conjunction with FOREST-BGC.

Simply change the directory to MTCLIM and examine the readme.doc file.