Simply stated, decomposition is the breakdown of matter into its basic components. When discussed in terms of environmental processes, it includes the breakdown of dead organic plant material by micro-organisms. When plant matter decomposes, it leaves behind sediment, or, a layer of "muck". This natural process is necessary so that waste matter doesn't accumulate and smother living material.
The processes of decomposition and sedimentation also take place underwater, such as on the bottom of a lake or pond. Over time, the build up of sediments on the bottom causes the lake to become shallower and shallower until one day the lake has turned into a marsh, or even a grassland or forest.
Where does all this organic matter come from? There are several ways in which organic matter is added to a waterbody:
As the lake becomes shallower, the emersed plants that grow along the shoreline start to grow towards the center of the lake, creating a marsh-like waterbody. These plants eventually die and decompose, creating more sediment buildup, creating a shallower waterbody, and allowing trees to start growing. A swamp now exists where there once was a lake.
These processes contribute to the natural aging of a lake: eutrophication. Eutrophication is the nutrient enrichment of a lake. Under normal conditions (without the added nutrients from human activities such as stormwater and agricultural runoff), eutrophication is a slow and natural occurrence that contributes to a lake becoming a marsh or swamp. The filling up of a lake can take hundreds to thousands of years. The rate of sedimentation can range from 1-10 millimeters a year. This translates to a rate of 3 feet per 1000 years and more.
AQUATIC PLANT MANAGEMENT AND LAKE PROCESSES
Even though sedimentation is a natural and slow process, some lakes become enriched and
shallow at a more rapid rate. Florida lakes, which are typically warm and shallow, are susceptible
to sedimentation and aging because these conditions are right for enrichment and plant growth.
For lakes that are used for recreation, water management, or aesthetic purposes, people may
choose to remove the sediment buildup in order to maintain the lake for its intended functions. See this story about the muck removal on Lake Tohopekaliga.
Many factors contribute to the life cycle of a lake including temperature, climate, shape
of the lake, oxygen concentrations, water chemistry, water movements, and as well as human
activities. Aquatic plant management is directly related to these factors which must be taken into
consideration when managing waterbodies.
This page was authored by Becca Hassell
Vic Ramey is the editor.
DEP review is by Jeff Schardt and Judy Ludlow.
A collaboration of
the Center for Aquatic and Invasive Plants, University of Florida,
and the Invasive Plant Management Section of the Florida Fish and Wildlife Conservation Commission.
The growth and proliferation of invasive aquatic plants speeds up the decomposition and
sedimentation processes. When nutrients are added to a waterbody, they cause plants to grow into
infestations. Plant managers then treat the lake, usually with herbicides, to eradicate the nuisance
plants. The dense concentrations of plants then die, decompose, and accumulate on the lake
bottom. Not only adding sediment, the decaying plants also use up oxygen in the water - oxygen
that native plants and animals need to survive.
When maintenance control methods are implemented, only a
small amount of invasive plants can grow before they are treated with herbicides. This reduces the
amount of dead plant material in the water, thus reducing sedimentation and oxygen depletion.
with assistance from Tara Muncaster and Aimee
Lyons.
Data is from the APIRS
database.
This page was designed and is managed by Becca Hassell.
CAIP-WEBSITE@ufl.edu
Copyright 2004 University of Florida