Does the natural decomposition of deciduous tree leaves form methane and contribute to global warming?

Question

Does the natural decomposition of deciduous tree leaves form methane and contribute to global warming?

Answer 1

No, because all of the carbon going into the atmosphere started there in the first place a year ago when the tree first grew those leaves.

Answer 2

Methane seems to form most commonly in anoxic conditions such as deep in landfills and in lake and ocean sediments, but it can occur as a by product of digestion as well:

""The leaf litter and duff layers consist almost entirely of stored carbon, so when the worms eat and process the litter and duff, they release carbon dioxide and possibly methane in their burrows"

http://www.sciencedaily.com/releases/200...

Oceanic methane deposits may have contributed to the Permian-Triassic extinction:

http://www.killerinourmidst.com/methane%...

Answer 3

First it should be known that both deciduous and evergreen trees lose their "leaves". Deciduous flora lose their leaves all at once (more or less) and evergreen flora lose and replace their "leaves" at about the same rate (which is why in most forests with pines, spruces, furs, etc you find needles all over the forest floor but no bald trees). To address methane production the answer is that it depends. Methane is primarily produced from anaerobic microbial facultative organisms which use alternate electron receptors for respiration. Since methane, even in rumanents, is produced by these organisms, a lack of oxygen is necessary for methane production. That said, if the tree leaves are decomposing in an oxygen-free environment they are giving off methane gas. This is common in the tundra up north where the warming of the Earth and the thawing of the land is heating up the soil enough that this type of decomposition can occur and millions of tonnes of methane are given off. However, on a forest floor at the surface or O horizon of soil, there is plenty of oxygen for aerobic decomposition. The chemical reactions for these events can be found in any soil-science book.

Decomposition in the presence of oxygen can be easily compared to composting although generally on the forest floor fungi and other macro/micro fauna lend to the break-down of materials as opposed to bacteria in composting. According to "The Nature and Properties of Soils" When organic tissue is added to aerobic soil, three general reactions take place:

1. Carbon compounds are enzymatically oxidized to produce carbon dioxide, water, energy, and decomposer biomass.

2. The essential nutrient elements, such as nitrogen, phosphorus, and sulfur, are released and/or immobilized by a series of specific reactions that are unique to each element.

3. Compounds very resistant to microbial action are formed, either through modification of compounds in the original tissue or by microbial synthesis.

As you can see, when oxygen is involved methane is not produced from natural decomposition.

As a side note there is some literature out there that plants give off methane "somehow" as no mechanism has been described and current studies do contradict eachother. Anti-global climate change nuts like the gentleman above may find this useful in their dogmatic stances but truthfully humans and plants cannot survive in high-methane environments. Plants, even if they did produce methane when alive, produce MUCH more oxygen as a byproduct of photosynthesis and thus could never contribute to global warming. Think about it: If your plants ever did produce that much methane, or if the rotting leaves outside produced enough methane to outweigh all the oxygen they produce, then we would quickly be asphyxiated and dead in our homes and out on our lawns. Just a thought.

Answer 4

The natural decomposition of deciduous tree leaves does form methane, but has no detectable influence on this planet's temperature.  By the way, if you didn't know already global warming already ended a few years ago and we are in a global cooling, oh Al Gore didn't tell you that did he!  Oh another thing, when we were in times of global warming so were all the other planets in this solar system!  If you haven't figured this out already, the temperature of the planets in this solar system are directly proportional to their distance to our central star called the Sun.  Oh, and one more thing, the temperatures of the planets in this solar system are directly effected by the temperature cycles of this solar system's central star called the Sun!  Don't assume those of influence know what they are talking about and DO YOUR OWN RESEARCH!  Besides the Global Warming scheme is too profitable to assume the politicians are telling the truth!  Global Warming is just a huge scam!  By the way, Polar Bears can swim over 100 miles you know!  The ice sheets have grown 60% over normal growth this winter!  Once again, DO...YOUR...OWN...RESEARCH!  Thank you for reading!