Mangrove

What is the BELT TRANSECT METHOD in mangroves?

1. Lay a baseline transect parallel to the shore across mangrove area 2. Establish perpendicular transects every 100 m (spacing may vary depending on forest extent) 3. Transects should extend toward the most landward mangrove zone 4. Set up 10 m × 10 m quadrats along transects (nested design)

What is quadrat spacing in mangrove forests?

1. Large mangrove forests → ~100 m intervals 2. Narrow mangrove strips → as close as 20 m

What is recorded inside each 10 m × 10 m quadrat?

1. Identify and measure all trees with DBH ≥ 5 cm 2. Record DBH for each tree

What is done within quadrat corners in mangrove sampling?

1. Place four 2 m × 2 m sub-quadrats 2. Record: Small trees (< 5 cm DBH) & Shrubs, vines, herbs, ferns 3. Count and identify all vegetation in sub-quadrats

How is DBH calculated?

DBH = CBH ÷ π

What is the general rule for DBH measurement?

1. Measure circumference at breast height (CBH) using measuring tape 2. Convert to DBH using DBH = CBH ÷ π 3. Round down DBH values to avoid overestimation and reduce error

How is DBH measured in a normal tree?

measure at 1.3 m above ground

How is DBH measured in sloped terrain?

measure 1.3 m from the upper slope side

How is DBH measured in an inclined tree?

1. Measure at 1.3 m following the tree’s axis from the lower leaning side

How is a forked tree measured for DBH?

1. fork above 1.3 m → treat as one tree, measure at 1.3 m 2. fork below 1.3 m → treat as separate trees, measure each stem at 1.3 m

How is DBH measured in a tree with enlarged stem base and buttress root?

DBH will be measured 30 cm above the highest buttress

How is DBH measured in a tree with aerial roots?

DBH will be measured at 1.3 m starting from highest aerial root

What is Importance Value Index (IVI)?

standard measurement in forest ecology to determine the rank relationships of species

What is the formula for Importance Value Index?

Importance Value Index = Relative density + Relative frequency + Relative dominance

What is Relative Density (%) formula?

No. of individuals of a species × 100 / No. of individuals of all species

What is Relative Frequency (%) formula?

Frequency of a species / Total frequency of all species × 100

What is Relative Dominance (%) formula?

Basal area of a species / Basal area of all species × 100

What is Basal Area?

(DBH in cm)

What does Shannon (H') Diversity Index measure?

1. Very High

What does Simpson’s Diversity Index (D) measure?

1. Measures probability that two randomly selected individuals belong to the same species 2. Focuses more on dominance of species 3. Often expressed as: 1 - D (higher value = higher diversity) 4. Lower D = higher diversity (if using original form)

What is Species Richness (S)?

1. Simply the total number of species present 2. Does NOT consider abundance or distribution 3. Higher S = more species in the area

What is Pielou’s Evenness Index (J')?

1. Measures how evenly individuals are distributed across species 2. Ranges from 0 to 1 3. 1 = perfectly even distribution 4. 0 = highly uneven (dominance by few species)