Biological adaptations to waterlogging

1. Conditions generating stress in saturated soils:

A. Lack of oxygen

B. Toxic forms of materials

C. Nutrient deficiency or unavailability

2. Anaerobic respiration

3. Physical adaptations:

Aerenchyma

Root ventilation systems

Root avoidance

4. Adaptations to toxicity:

External toxic substances

Internally generated by-products

5. Waterlogging effects

A. Temporary flooding: increased growth

B. Prolonged flooding: trees

Decrease in function:

Water and nutrient uptake

Photosynthesis and transpiration

Metabolic changes

Tolerant spp.: no change

Intolerant spp increase metabolic rate

Visible damage:

Leaf chlorosis

Downward curling leaves

Leaf abscission

Absence of fruiting

Increased susceptibility to predators and pathogens

Branch dieback

C. Prolonged flooding: seedlings

6. Factors which modify the effect of waterlogging

A. Time-of-year

B. Flood frequency

C. Flood duration, speed of floodup and drawdown

D. Flooding depth

E. Siltation

F. Other: rainfall, moving water, cool water