Download Methods of ecological study of fitocenosis

Methods of ecological study of fitocenosis
At sup. Plants
It is made on a sample surface (minimum area of probe) minimum surface with maximum
of sp.
a)For moss and lichens=10 square cm
b)For vegetation on the alpine rocks(saxicole)on the bare rock=1square meters
c)For the salts,sands and rabies(where the veg. is more uniform)=10square cm.
-To capture maximum species
-The nature of the substrate
-Soil chemestry
-Bog’s pH
The variation of salt on the soil profile, is performed with probes
At sand :
- size of sand grains
- the nature of the sand (wind,formed on water and from battled rocks)
- amount of organic substances
d)for reeds=10 square meters
e) for floating vegetation=100 square meters
f) for meadows=100 square meters. The surface is marked with strings and the study
of continuity in all seasons of vegetation.
All data on floristic composition and fitocenosis structure is noted in a chart named:
MAPPING
MAPPING
1.Date
2.Place
3.Altitude
4. Place exhibition
5.Slope( expressed in degrees-measured with an echimeter)
6.Probe surface
7.Vegetation coverage
8.Photography
9.Floristic composition(trees,bushes,grass species)
10.Informations about microrelief(leveled,accidental,low)
11.Soil type and mother rock
12.Usage mode( hayfields, pasture, forest cut)
13. Datas from the city hall
14. Data from Forestry(number of plots, the proportion of essences)
15.Other data about fires, defoliations
16. Treatments with pesticides
From the weather station we must have information related to
- rainfalls
-
brightness
fog
cloud
direction and wind power
The rare plants can be photographed.
Such a study ends with practical hints.
Estimating population density
- Direct method
The plants are counted. From where we make the observation
Method – network type
We take a surface of 16 square meters
L = 4 meters
We take one quarter of the surface
L = 2 meters
We take one quarter of the surface
L = 1 meter
There are counted the individuals from the species we study
Population density = number of individuals / unit area
If we calculate the effective we can find out the density
Density of trees/hectare - by at least 5 counts in each area of 1000m
In the meadow – the density 1 square meters – the measurements must be done by more than
5 times to be as close to the real density
Ways of knowing the number of population :
a) the census
b) the estimate
1. Frequency(F)=number of evidences in wich there is found a sp./nr.of probes collected
F=p/P*100
WHERE:
p-number of evidences in wich it is found the given species
P-total number of collected probes
2.(Relative)abundance= number of idividuals from a sp./number of individuals from other sp
from a given surface
A=n/N*100
In fitocenosis abundance case .It is made after the Braun-Blouchet scale
1-very rare individuals
2-rare individuals
3-less numerous individuals
4-numerous individuals
5-very numerous individuals
3.Dominant
Da=n/N*100
Where:
Da=dominant sp.A
n=number of individuals from sp.A
N=number of individuals belonging to the sp..Different fitocenosis
This shows the coverage area of the ground from the aerial parts of a plant population
1- covered less than 1/10 of the total probe surface
2- covered from1/10-1/4
3- covered from1/3-1/2
2- covered from1/2-3/4
4- covered from 3/4-4/4
4.The ecological index significance (W)
W=F*A*100/10000
WHERE
F-frequency
A-abundance
W1=0,1 sp.Accidental
W2=0,1-1%
W3=1-1,5 sp. Accessories
W4=5,1-10%
W5=over 10% the sp. caracteristic for the biocoenosis given