Not unless accelerated with bacteria. Usually takes months.
1000's of year
eight weeks - two months
Keep and gather them in a mulch bin then when they decompose Mix them in with the garden soil
When the leaves and bark of a plant fall onto the ground, they decompose forming nutrient rich brown mulch. This mulch later turns into soil with age.
Bread will begin to decompose in a couple days. It can take 2 to 3 weeks to completely decompose.
Cardboard takes about 2 weeks to decompose in the ocean.
It takes about 3 to 4 weeks to decompose a paper bag.
Most leaves will decompose in a few weeks if they are in a moist climate.
Mulch itself is not alive, however within a few weeks or days there is a lot of life working with mulch to break it down. There are different bacteria and fungi that break it down into humus (not the kind you eat) and other nutrients. This is why you have to continue to apply mulch and also why aged mulch is good to plant in.
2-5 weeks
Usually 3-4 weeks
10-15 weeks