Tuesday, November 23, 2010

Leaf Litter Decomposition

     Decomposition of leaf litter is a major means of recycling nutrients in forest ecosystems. The process is carried out by bacteria, fungi, and soil fauna.  It begins in earnest about 2 months after the leaves fall but decomposition may not be complete for up to 18 months.  As the fallen leaves are broken down by insects and microbes, their carbon, nitrogen, phosphorus and other nutrients become available for uptake by plants within the local environment.  Litter accumulates annually creating a layering effect with the most accessible nutrients underneath a layer of less decomposed material.  Precipitation washes organic nutrients into the soil layers below.  Decomposition is also a major pathway by which carbon, fixed during photosynthesis, is returned to the atmosphere.

Partially Decomposed Leaf Litter

     The primary influences on the rate of leaf litter decomposition have been shown to be temperature and water loss due to evaporation and transpiration.  Another important factor is litter quality, the ratio of carbon to nitrogen and nitrogen to phosphorus.  Surprisingly, precipitation is secondary.
     Understanding the processes and factors controlling leaf litter decomposition is important for studying nutrient cycles, developing carbon budgets and assessing it's role in global climate change.


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