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
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
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.