Pteris vittata L.

Humidity Value H

1

very dry

1⁺

dry

2

moderatly dry

2⁺

moist

3

medium wet

3⁺

wet

4

very wet

4⁺

soggy

5

submerged or underwater

f

plants living in running water

u

mostly submerged plants

v

partly submerged, partly floating plants

w

humidity moderately variable (± scale of 1-2)

w⁺

highly variable humidity (scale exceeding ± 2)

Reaction Value R

1

Very acid (pH 2.5-5.5)

2

acid (pH 3.5-6.5)

3

lightly acid to neutral (pH 4.5-7.5)

4

neutral to basic (pH 5.5-8.5)

5

basic (pH 6-5 -> 8.5

Nutriments value N

1

very low in nutrients

2

low in nutriments

3

medium-poor to medium-rich in nutrients

4

rich in nutriments

5

very rich in nutriments

Salinity tolerance

1

halotolerant

3

halophyle

Light Value L

1

very shady

2

shady

3

lighted areas

4

luminous

5

highly luminous

Temperature factor T

1

alpine to nival stages (from the treeline to the snowline)

1⁺

suprasubalpine and upper subalpine levels (pine and larch forests)

2

subalpine level (coniferous forests without beeches up to the upper limit of spruces)

2⁺

lower subalpine and upper mountain stages

3

mountain level (beech and silver fir forests, in the central Alps Scots pine forests)

3⁺

lower mountain and upper hill levels

4

hill level (mixed deciduous oak forests)

4⁺

hot places, hill level

5

very hot places, hill level (only in the hottest places, typical of southern Europe)

Continentality K

1

Atlantic (high air humidity, very low temperature variations, mild winters)

2

Sub-Atlantic (high air humidity, low temperature variations, relatively mild winters)

3

sub-Atlantic to subcontinental (average air humidity, moderately variable temperature, slightly low winter temperatures)

4

subcontinental (low air humidity, large temperature variations, rather cold winters)

5

continental (very low air humidity, very large temperature variations, cold winters)