Assessing Forest CommunitiesAssessing Forest Communities

Ani Mardiastuti

Canopy StratificationCanopy Stratification

A

B

C

D

E

4 layersy

3 layers3 layers

2 layersy

Assessing Forest Communities

1. Density

2. Basal Area/Dominance 

3. Frequencyq y

4. Canopy cover

5 Species Diversity5. Species Diversity

Important Value Index = INP 

Measuring the size of treesMeasuring the size of trees

• Diameter breast height (dbh): 1 30 m• Diameter breast height (dbh): 1.30 m

• Measures the girth of a tree

• Estimates age of the tree

–Saplings vs mature–Saplings vs. mature

• The larger trees (older trees) have the greatest impact on the other trees in the forest

Measuring the size of treesMeasuring the size of trees

Trees with buttress Trees with rhizophores

DensityDensity• Number of individuals per unit area or volume, regardless of speciesregardless of species 

• For example , if 11 trees were found in 5 ha, the density would be 2 2 trees/hadensity would be 2.2 trees/ha

• Definition of trees– Mature tree (pohon): diameter > 35 cm (or 20 cm for some– Mature tree (pohon): diameter > 35 cm (or 20 cm for some habitat)

– Poles (tiang): min diameter 20 cm up to <35 cm

– Sapling (pancang): 1.5 m up to diameter 20 cm

– Seedling (semai): up to 1.5 m

DominanceDominance

• For mature trees onlyFor mature trees only

• Basal area (luas bidang dasar) measures the area occupied by a treearea occupied by a tree  

• It is reported in meters2/hectare or ft2 per acre

• Big, ‘fat’ tree: dominant 

• Height of a tree: excluded in calculation

Basal AreaBasal Area

• Basal area/ha could be used as an indicator ofBasal area/ha could be used as an indicator of the level of degradation or status of standing stockstock 

• If the basal area is declining, it can be safely concluded that the forest is degradingconcluded that the forest is degrading

FrequencyFrequency

• The occurrence of a certain species in aThe occurrence of a certain species in a designated plots

• High frequency vs low frequency?• High frequency vs. low frequency?

• Frequency vs. abundance?

• Frequency vs. dominance?

• Frequency vs. density?q y y

Metoda Garis BerpetakMetoda Garis Berpetak

Grass and ground coverGrass and ground cover

Indeks Nilai Penting (IVI)Indeks Nilai Penting (IVI)

Kerapatan (Phn/Ha) = Jumlah Individu Suatu Jenis

Luas Seluruh Petak

KR (%) =Kerapatan Suatu Jenis

x 100 %Kerapatan Seluruh Jenis

Dominansi (m2/Ha) = Luas Bidang Dasar Suatu Jenis Jumlah Seluruh Luas Petak Contoh

DR (%) = Dominansi Suatu Jenis x 100 %Dominansi Seluruh JenisDominansi Seluruh Jenis

Frekuensi = Jumlah Petak Ditemukan Suatu JenisJumlah Seluruh petak Contoh

FR (%) = Frekuensi Suatu Jenis x 100 %Frekuensi Seluruh Jenis

INP = KR + DR + FRINP = KR + DR + FR

How to measure/determine …How to measure/determine …

• Tree heightTree height

• Branchless tree height (tinggi bebas cabang)

C l• Canopy closure

• Canopy diameter

• Canopy depth

• Leaf Area IndexLeaf Area Index

• Tree architecture

CoverCover

• Cover: A measure of the vertical projectionCover: A measure of the vertical projection onto the ground 

• It can include overlaps or not• It can include overlaps or not

• Cover is often summarized by broad "cover‐b d l ”abundance scales”

• It would be better to be much more precise if you are interested in monitoring fine‐scale patterns.

Vegetation Profile

Forest Garden (kebun, talun)

Take Home Exam ITake Home Exam I

• Collect data• Collect data

• Calculate INP