population dynamics: seeds + transport + reproduction

why is understanding population dynamics important?

• better predictions of invasions and spread

• determinations of '“weediness”

• predicting transfer of genetic characteristics (resistance)

• provide insights into biological and ecological mechanisms for aiding in weed management.

seed abundance in the soil

120 million - 1.4 billion in an acre

10/11 - 20 - packed on a 1” by 1” square

seed distribution

tillage type affects seed incorporation depth

moldboard plow flips the soil so seed is distributed mostly evenly throughout depth

• very inconsistent and depends on frequency

light chisel plow leaves much on the top and some down in

ridge till mixes more with middle level highest

if we aren’t tilling how do seeds make it down into the soil further?

seed survived from past management strategy

animals/insects/invertebrates move seeds down into the profile

water flow

how texture affects deposition

soil tex

seed persistence

seeds with less of a coat persist less

thistles 20 yrs

lambsquarters rr pigweed 40 years

***think about averages and the species they are related to

external factors affecting seed viability

silage

• heat - may stimulate germination

• ph change

• dependent on species it can be really good at controlling most species however length of ensilage may need extended to destroy (of small thinly protected seeds)

manure storage

• some seeds degrade very quickly when stored; again very variable on how long you have to store in order to destroy the seeds

digestive tract

• digestion can decrease germination, if you use manure storage after the combination is the best.

• digestion does not completely control germination