Leaf area index
The leaf area index ( BFI , LAI from Leaf area index ) is a key parameter in the calculation of global climate scenarios (carbon dioxide emissions from plants) and the assessment of the ecological structure of, for example, grasslands. The leaf area index also describes the influence of agricultural, forest and natural vegetation on runoff formation .
definition
The leaf area index is defined as the leaf area per soil surface, BFI = A (leaf) / A (soil) (dimensionless).
Here, leaves are counted on one side and needle leaves are projected onto the ground. A BFI between 0 and 1 means that there is less leaf area over one unit of soil area. If BFI = 1, the areas are the same, and if BFI> 1 there is more leaf area than the floor area below.
Examples:
| place | BFI |
|---|---|
| Field (winter) | 0.2 |
| Intensive meadow (summer) | 7th |
| "Ordinary" grassland | 1-2 |
| Coniferous forest | 5 |
| Douglas fir | 10-13 |
| Spruce | 5-10 |
| Beech (summer) | 6-8 |
| Oak | 5-7 |
| Scots pine | 3-4 |
| European larch | 2-4 |
| Beech forest (winter) | 0.2 |
| Maize (32 plants / m²) | 10 |
| Maize (8 plants / m²) | 4th |
Special
The extent to which leaves absorb rain depends on the type of plants, the density, the time of year and the cultivation method. This effect also determines how much water reaches the soil or is previously lost as initial loss for wetting and through evaporation . The amount of water that evaporates before it hits the ground is called interception . This is particularly important in areas with little rain, because there the wide cultivation of narrow-leaved varieties is advantageous.
The rain shadow of the leaves also has an indirect effect on the infiltration , as it softens the silting up of the topsoil.
In general, the more uniform the stocks are, the more generally binding the BFI is. Plantations and agricultural crops can therefore be assessed relatively precisely using tabular values, whereas the BFI of natural forests varies over wide areas and must be calibrated by measurements.
Leaf area density
The leaf area density ( BFD , English LAD from Leaf area density) is calculated from the BFI by dividing it by the stand height. If you consider individual layers of the existing structure, the BFD results from the BFI per cubic meter (m² / m³). The BFD is interesting insofar as it can provide information about the light profile in existing buildings.