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A short note on the significance of leaf litter

February 6, 2013

It has been said many times before; a leaf litter layer in a forest reduces erosion by softening the force of tropical rains, reduces water losses due to evaporation and lowers the temperature around roots in deciduous forests. The leaf litter provides food for earthworms which keep the soil aerated and more porous, of benefit to root growth. In addition, the leaf litter is the home of many interesting critters.

One may argue that annual burning would reduce fuel accumulation, preventing dangerous fire storms near cities. That might be true for some areas of the world with short or unreliable rainy seasons and absence of termites, but the experiment has been done at a large scale in Chiang Mai, where the eastern side of the Doi Suthep mountain has been spared from fires for many years, largely thanks to determined lobbying from the Chiang Mai University. As everyone in town can notice, the mountain flourishes and there have not been any fire storms. The fuel is kept at a naturally moderate level by termites and to some extent by fungi.

In a man-made woodland or parkland one could consider increasing the volume of the leaf litter during the initial years when the trees are too young to produce leaves in abundance. We do so at Dokmai Garden, and as a result we enjoy copious amounts of delicious mushrooms, and it has also changed the behaviour of our hens. Previously they would lay their eggs on top of arbours or in the space between tree trunks. With the generous leaf litter, they lay their eggs on the ground. Domesticated chicken is the same species as the wild red jungle fowl (Gallus gallus), and they are adapted to searching food in the leaf litter (reducing the number of scorpions, snakes, snails, slugs and centipedes) and apparently also to roost there.

In a national park management plan, it should be emphasized that annual man-made fires can not be tolerated, as they will kill seedlings and reduce the biodiversity significantly. Rotating pockets of natural fires many years apart enhances biodiversity by regeneration, but annual fires of vast tracts prevents restoration of the devastated Southeast Asian forests.

Leaf litter Feb 6th.2013.72

A Dokmai Garden scenery from 08.00 this morning.

Text & Photo: Eric Danell

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7 Comments leave one →
  1. February 6, 2013 9:36 AM

    Hi Eric, thanks for this. I wish this would be translated in Thai and that everyone in Chiang Mai would read this.

    • February 6, 2013 10:09 PM

      There is a lot of efforts from the central Thai government, courses for villagers and educational efforts via schools and media. Old-timers do not care though, so we simply have to wait until they are replaced by younger and more well-educated generations.

  2. February 6, 2013 10:09 AM

    Sorry Eric, I must contradict you, but not your view of the benefits of not burning. The Eastern face of Doi Suthep burns in most years as I can see from my bedroom window, and as a result the forest is highly degraded and flash floods, which are worsened by the lack of leaf cover and friable soil cause serious damage. There is one small area where this is not the case and that is around Wat Palat just west of CMU main campus where burning has been excluded, not due to CMU’s help however.
    Also you mention “natural fires”, but apart from insignificant tiny spot fires associated with lightning strikes during the rainy season we do not have evidence that natural fires occur. Maxwell, who has collected plant specimens on Doi Suthep for over 20 years and lives at the foot of the mountain, is of the opinion that forest fire is not a natural phenomenon in the Thai forests.
    Your readers should note that as of January 2013, any lighting of fire in the forest is an offence punishable by a jail sentence.

    • February 6, 2013 10:18 PM

      Thanks Ricky,

      I just tried to show one good example, but maybe that example is not that good. Indeed the interval between natural fires can be debated, and only studied once we have truly protected forests.

      There is nothing wrong with the Thai law, but there is no enforcement. We did consider offering police a two hour course on orchids and orchid conservation, but my experience from our gardeners is that they have not learnt anything in six years, so why would somebody who spends two hours want to learn anything?

      All efforts have to be aimed at schools and younger generations, and until they have replaced today’s pyromaniacs we just have to endure.

  3. marcel Prahin permalink
    February 6, 2013 7:52 PM

    Hi Eric,

    How could someone loving green not agree with you about leaves to be kept when they fall in the forest and about the fact that fires should be prohibited as much as possible.
    A part of our property(in Phuket) is still a real forest with big trees(just great and lucky to have it still). On the other end our young garden with fruit trees would love and need the addition of leaves especially from now to the end of May(hot season) until before the first rain. The point is that there are quite many cobras and other poisonous snakes around and as from next month until May it is their pregnancy and delivery time. And they are loving to stay into bunch of leaves to keep their eggs at the right temperature. I wonder if you would have some advise to keep them away(somehow) although helping young trees with leaves to have some freshness ?

    Thanks in advance and green day to you

    • February 6, 2013 11:29 PM

      Dear Marcel,

      Indochinese spitting cobra is indeed a common species in Thailand, especially in rice field areas where their main prey, amphibians, reside. To lower the density of cobras at Dokmai Garden to currently one sighting a year we have:

      1. 15-20 chicken per 25 rai. They can keep hatchlings and other smaller venomous critters at low numbers.

      2. Fenced the area, using a small mesh and rust-free chicken-net which we have dug into the soil. Snakes can climb if they really want to get inside, but many snakes simply follow an obstacle.

      3. Taught our staff to walk slowly and most venomous critters disappear even before they see them. Teach the staff not to attack the snakes; 90% of the snake bites are men bitten in their hands. I have never seen an angry cobra in nature, only on TV and at snake shows.

      The statistics may help you realize whether cobras are a problem or not: there were over 88000 Thai traffic accidents with over 13000 dead in 2008 (http://www.thaiwebsites.com/caraccidents.asp). The number of murders in Thailand was 4435 in 2007, about 12 per day (http://www.unodc.org/unodc/en/data-and-analysis/homicide.html). The number of deaths from snake bites in Thailand in 2007 was estimated at maximum 94 (http://www.toxinology.org/GSI-epidemiology2.htm).

      It seems there are 1700 times more deaths due to people than due to unprovoked snake bites. During my six years in Thailand I have not met with a single person who later died from a snake bite, while I have met with two people who were later murdered and far too many acquaintances and friends dying in traffic accidents.

      I believe you are much safer in a fruit orchard with cobras, than on a motorbike downtown 😉

      • marcel Prahin permalink
        February 7, 2013 4:09 PM

        Thank you for these infos and advises I will follow your advise of fencing the area, using a small mesh and rust-free chicken-net duged into the soil. The few figures are always a help
        to take a bit of distance… 😉
        Good day

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