Posted on

weed seed dispersal mechanisms

Specialized mechanisms of some weed species to bury themselves: wild oat hygroscopic awns that twist themselves into the soil (self-seeding)

Selection for time of seed release: adaptation for quick or slow release from parent plant?
-quick release: oversaturate predator demands of feeding and leave enough after that for new colonizers
-slow release: maximize chance some seeds land on ground during favorable time for quick germination or escape from predators

Wind dispersal of weed seed is a function of:
-how fast seed falls: weight, density, ability to float in air
-height of release: may be most important factor in distance spread; mullein seed
-speed, direction and turbulence of wind between release point and ground
-very light, dust-like seed (poppies; fungal spores)
-species with specialized wind dispersal mechanisms generally don’t colonize as a horizon but as isolated individuals over a greater distance

Ants play important role, especially in storage concentrations

Human dispersal
-new continent, region invasions
-local dispersal: machinery, crop seed contamination

Animal behavior affects where the moved seed ends up, and its success thereafter:
-the territorial and migratory behavior of animals dispersing seed
-animal feeding (eating, digestion) affects seed viability
-animal storage of seed: distance, concentration, location;

Specialized mechanisms of some weed species to bury themselves: wild oat hygroscopic awns

Specialized structures:
a. burrs: cocklebur, sandbur seed
b. appendages: beggarticks seed

preventative weed control is very important

Ants play important role, especially in storage concentrations

Post-Dispersal movement of seed

Animal storage of seed: distance, concentration, location

invasion from the outside overemphasized