# A holistic microclimate model

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# Plant Database PLANTS.DAT

## Introduction

Plants are more than just porous wind shelters in ENVI-met. The model allows to define any plant from small grass up to huge trees using the same database scheme.
The main database PLANTS.DAT is stored in the \sys.basedata folder. You can used this file or use local databases containing more plant definitions.
Use local databases to define plants which are specific to your simulation and should not be stored in a global file. If you create a model area and need new plants in ENVI-met, you should add them to a local database, too. If you transfer this simulation file to another computer, don't forget to transfer you local database with them.

This is an example of a PLANTS.DAT: (Columns LAD2 to LAD9 and RAD2 to RAD9 are dropped here)

**************************ENVI-met Vegetation Database V3**************************

MO C3 01  400 0.20 20.00 02.00 0.040    0.000 0.100     0.100 Tree 20m aver. dense., no distinct crownlayer
DO C3 01  400 0.20 20.00 02.00 0.110    0.000 0.100     0.100 Tree 20 m dense., no distinct crown layer
DM C3 01  400 0.20 20.00 02.00 0.075    0.000 0.100     0.100 Tree 20 m dense., distinct crown layer
dm C3 01  400 0.20 20.00 02.00 0.075    0.000 0.100     0.100 Tree 20 m dense., distinct crown layer
ds C3 01  400 0.20 10.00 02.00 0.075    0.000 0.100     0.100 Tree 10 m dense.,distinct crown layer
sm C3 01  400 0.20 20.00 02.00 0.150    0.000 0.100     0.100 Tree 20 m very dense, distinct crown layer
H2 C3 01  400 0.20 02.00 01.00 2.000    2.000 0.100     0.100 Hedge dense, 2m
T1 C3 01  400 0.20 10.00 02.00 0.000    0.000 0.100     0.100 Tree 10 m very dense, leafless base
g C3 03  200 0.20 00.50 00.50 0.300    0.300 0.100     0.100 Grass 50 cm aver. dense
bs C3 01  400 0.20 20.00 02.00 0.000    0.000 0.100     0.100 Tree 20 m dense.,distinct crown layer
m C4 03  200 0.20 01.50 00.50 0.300    0.300 0.100     0.100 Maize, 1.5 m

V3 indicates that the database is in format V3 which I assume to be the case after more then 4 years of using this format.

## What do the lines and columns mean?

This entry defines whether a plant is of a C3-type (most of the plants) or of a C4-type (e.g. maize). C3 and C4 plants have different ways how to handle the CO2 fixation, but explaining this would go beyond this manual. See a botany book if you want to know more about this.

Most of the columns of the database are filled with the LAD (Leaf Area Density) and RAD (Root Area Density) profiles for the plant. Both are given in m2 leaf (or root) surface per m3 air volume.

There are some example trees in the file (all deciduous) and there are other profiles available in literature.
The profiles are normalized from z/H=0.1 (LAD1 and RAD1) to z/H=1 (LAD10 and RAD10) where z is the height of the LAD or RAD entry and H is the total plant height or the depth of the root zone.
So you always need 10 entries, this is the same for a 50cm grass and a 100m tropical tree. The profile will then be stretched or compressed to the actual grid point size in the model.

The columns in detail:

ID:           Like in each other file, there is the Plant ID.
You enter this two-digit ID into your Input File to define where your vegetation is.
Only alpha numerical ID's should be used here, otherwise ENVI-met interprets them as buildings!

C?:           Defines the type of plant according to the CO2 fixation.
Valid entries are "C3" and "C4". Missing or invalid data will be taken as "C3".

TY:           Plant Type, 01 for deciduous trees, 02 for conifers and 03 for grass.
This information is used to calculate the leaf diameter and aerodynamic properties

rs_min:       minimum stomata resistance of the plant.
Keep it to 400 for trees and 200 for grass unless you are an expert and have special information
rs_min is only used for the (old) Deardorff-Approach.
If you use the A-gs model (recommended), rs_min has no influence on the calculation of rs

a_f:          short-wave albedo of the plant leaf and normally 0.20 unless you have a very special plant.

HH.HH:        The height of the plant  in [m].
Defines what you finally get inside your model area: a small flower or a huge tree.

TT.TT:        Total depth of the root zone in positive values.
The water transpired by the plant will be taken from the soil moisture using the
soil root distribution as a relative weighting function.

LAD1 to LAD10: The Leaf Area Density in m²/m³ for the 10 data points, see above

RAD1 to RAD10: The Root Area Density in m²/m³ for the 10 data points, see above

Name:          Given name for the plant

Important to know:

• The name of the database used by ENVI-met can be selected in the Configuration File. Also, you can keep this entry empty if you want to ignore all plants in your Model Area!
• The ID's are case sensitive: “DM” is not the same as “dm”!