QRY: Evidence of reforestation increasing rainfall?

Discussion in 'The big picture' started by cjwardle, May 28, 2009.

  1. cjwardle

    cjwardle Junior Member

    Joined:
    May 16, 2008
    Messages:
    5
    Likes Received:
    0
    Trophy Points:
    0
    I'm running into a research stumbling block and wonder if this somewhat public musing could tap into the greater wisdom accessible through cyber-networking?
    But first some background ...
    A month or so ago I was doing some bushwalking in the North-East of Pakistan's Balochistan Province, with one of my younger brothers-in-law, Danish. As we reached the top of a large mesa-like hill called Dhera and looked out at his - and my beloved's - home village of Phugla to the north, we were struck by how few trees we saw.
    This got us to chatting about climate change, the area's potential for agro-forestry, and the possible impact of large scale tree planting on the weather pattern.
    Within twenty kilometres to the northwest, native Olive trees thrive in the area's sandy soils and hot summer, which prompted me to ask, "With a similar climate and soil, why don't people look to plant commercial Olive varieties here?"
    It was a question we later repeated with community members and their answers seemed to confirm our prediction that it rested somewhere between:
    * a lack of awareness,
    * an unwillingness to collaborate or experiment, and
    * no patience to wait for the long-term gains offered through agro-forestry.
    Well, these are challenges we’ll return to another time, but as we discussed climate change, Danish noted that there was much more reliable rainfall fifteen to twenty years ago and remarked that if tree loss accounted for a decrease in rainfall, would reforestation improve the rainfall pattern and how much effort would people have to put in, to effect real change?
    "Specifically," he asked, "how many trees would every person in this community have to plant, in order to increase our rainfall - five, ten, fifty trees each?"
    In answering I said I didn't know, but thought it might be in the order of thousands, but that was just a very rough guess and I would go and find out for him.
    So, after a very long introduction, here's my question:

    Is there any well-documented evidence that reforestation mitigates the negative impacts of climate change by increasing rainfall, and on what sort of scale do we begin to see such effects, if they exist?


    When I look at policy-level climate change mitigation strategies, I consistently read that we need to plant more trees, but this seems to be based on documented evidence of tree loss. Sure, there is evidence that tree planting decreases erosion and increases soil moisture retention, but I am yet to find references to positive rainfall gains from reforestation.
    Please don't get me wrong, I'm very much on board with this issue. In the previous century I've encouraged and worked with my children on community tree plantings in my home town of Darwin and on saving the one remaining remnant of tropical rainforest on the fringe of Darwin city - the Duke Street Rainforest. More recently, my beloved Maha and I spent four wonderful months of joyful, practical learning during our voluntary permaculture internship on an organic coffee plantation in Nepal.
    In my heart of hearts and from my permaculture training, I feel that a reforestation strategy should work to increase rainfall, but my attempts to uncover hard evidence keep running into a brick wall.
    Maybe I'm not using the right search terms or looking in the right places, so I turn to you, dear reader, for guidance and possible permaculture solutions and research experience in this regard.
    Thanks in anticipation of your kind responses and my apologies for cross-posting.
    Looking forward to hearing from you in due course and wishing you salaams from Quetta,
    Chris Wardle.
    ===========
    skype: cjwardle
    mobile: +92 333 784 1679
    ===========
    View my profile on
    LinkedIn: https://www.linkedin.com/in/cjwardle
    or
    facebook: https://www.facebook.com/profile.php?id= ... ef=profile
     
  2. duanejen

    duanejen Junior Member

    Joined:
    Jul 23, 2007
    Messages:
    45
    Likes Received:
    0
    Trophy Points:
    0
    Re: QRY: Evidence of reforestation increasing rainfall?

    Some of the research you are is at viewtopic.php?f=6&t=10455 where Russian research published recently in New Scientist validates this and substantiates what James Lovelock, of Gaia fame, spoke of when he said 'vegetation mitigates the landscapes climate by acting as the air conditioners of the planet'.

    The simple answer is yes it can be done....not with monocultures but with biodiversity as the key.

    see https://www.newscientist.com/articleimag ... dwide.html for diagram
    plus
    see https://www.newscientist.com/article/mg2 ... ?full=true for the New Scientist article.
    Perhaps someone out there can load the graphic on this blog....I am unsure of the process of loading images.
     
  3. gardenlen

    gardenlen Group for banned users

    Joined:
    May 14, 2004
    Messages:
    3,464
    Likes Received:
    0
    Trophy Points:
    0
    Re: QRY: Evidence of reforestation increasing rainfall?

    just want to throw my support in here. the new age science that supports the greed of gov' and industry will never agree to this premise, and they are the ones that hold sway as our short sighted gov's fail in the job to run our societies sustainably within the planets capacity.

    yes as duanejen, says it must be bio-diversity that is the forest as they were, originally agri-forestry won't do it(and when that becomes painfuully obvious those scientists will then have extra leverage to say "there told you so trees don't work"), and not just the more attractive rain forest but all bushland the good the bad and the ugly. that's right across our nations to our desert centres not just the coastal strips.

    the way i see it our states are getting colder in winter hotter in summer because of the degredation of the brigalo and mulga buffer zones all in the name of growing food un-sustainably and creating a desert type landscapes along the way. we ahve a state planting un-workable wind farms instead of habitat which would help increase there ever lessening rain fall and reducing livable areas.

    len
     
  4. Ojo

    Ojo Junior Member

    Joined:
    Sep 6, 2007
    Messages:
    490
    Likes Received:
    0
    Trophy Points:
    0
    Re: QRY: Evidence of reforestation increasing rainfall?

    Isotopic studies of rainwater collected at various points in the Amazon basin indicated that nearly half of the total rain came from water originating in the ocean and half transpired through the vegetation. Evidence of the proportion of transpired water in rainfall reaching as high as 88 percent has been reported for the Amazon foothills of the Andes. General climate
    circulation models indicate that, without transpired water from plants, rainfall in the central regions of the continents would be greatly reduced. As a general rule, the farther the distance from oceanic water sources, the higher the fraction of rainwater originating from transpiration.
    excerpt
    https://www.britannica.com/EBchecked/top ... -processes

    Transpiration is an important part of the water cycle. A large proportion of rain falling on land is transpired by plants back into the atmosphere.

    In natural bushland surrounding Sydney, most rainfall enters the soil and 60% of the total rainfall is returned into the atmosphere by plant transpiration. In the suburbs there are not as many trees and only 10% of rainfall is transpired into the air and most rain lands on streets and houses then flows swiftly down gutters.

    In Sydney a large gum tree transpires up to 200 litres of water a day. A well maintained garden in Sydney will transpire nearly twice the volume of water as the total rainfall.
    excerpt
    https://www.ramin.com.au/creekcare/trees.shtml
     
  5. Jana

    Jana Junior Member

    Joined:
    Oct 22, 2006
    Messages:
    393
    Likes Received:
    0
    Trophy Points:
    16
    Re: QRY: Evidence of reforestation increasing rainfall?

    Firs were planted in Tlemcen valley in Algeria on the verge of the Sahara and this bought in snow every year. www.kheper.net/topics/Theon/Alma.html

    The Man Who Planted Trees by Jean Giono is a beautiful tale of the regeneration of land, rivers and human community through one mans efforts of tree planting. A forested earth holds more water in the watertable, humus layer and biomass, also it aids in cooling through increased evaporation, this would tend to keep water more on the land and less in the oceans.

    “Trees are known to evaporate more water than even lakes, due to the surface area of the leaves. So the more deforestation the less evaporative cooling of the land…the slower the evaporation cycle and the more droughts and flooding occur. Because there is less evaporative cooling this means a hotter more humid climate. By planting more trees, evaporative cooling is increased, speeded up the evaporative cooling cycle, so the more trees, the cooler the land and the more rain. By speeding up the evaporative cooling cycle we can slow down the carbon dioxide global warming taking place.” Brett de Courcy Harris, Speeding up Evaporative Cooling to Minimise the Symptoms of Global Climate Change. Brett is Windguy at www.theenvironmentsite.org/forum/

    Forests affect climate in three different ways: they absorb the greenhouse gas carbon dioxide from the atmosphere and help to keep the planet cool; they evaporate water to the atmosphere and increase cloudiness, which also helps keep the planet cool; and they are dark and absorb a lot of sunlight, warming the Earth. https://www.sciencedaily.com/releases/20 ... 220936.htm

    The people of Gaviotas grew Pinus caribaea (Hondoras pine) on their savanna...this was the only thing that would grow other than the existing grasses...then overtime the native rainforest species started to infiltrate the pine forest as the soil ecosystem started to upgrade. None of this would have occurred without the Pizolithus tinctorius mycorrhiza that cohabited with the pine trees. www.accessmylibrary.com/coms2/summary_0286-31746133_ITM
    A tropical forest like Las Gaviotas helps to increase cloudiness and rainfall through a process known as transpiration and condensation. www.gaviotasoffsets.org/offsets_main.html
     
  6. gardenlen

    gardenlen Group for banned users

    Joined:
    May 14, 2004
    Messages:
    3,464
    Likes Received:
    0
    Trophy Points:
    0
    Re: QRY: Evidence of reforestation increasing rainfall?

    wasn't it the late Masanobu Fukuoka who said:

    "plant the plants and the rain will come"?

    by plants i would imagine he means the whole gammit shrubs trees etc.,. a whole biodiversity.

    len
     
  7. Tim Auld

    Tim Auld Junior Member

    Joined:
    Jun 28, 2008
    Messages:
    38
    Likes Received:
    0
    Trophy Points:
    0
    Re: QRY: Evidence of reforestation increasing rainfall?

    I'm fascinated by this topic too. My home region, The Riverland, in South Australia in frequently suffering from a dearth in rainfall and I wonder how it relates to the widespread scrub clearing used to prepare land for wheat and other crops.

    Here's a fascinating presentation you will enjoy, about a well documented reforestation project in borneo. It didn't go under the name of permaculture, but it uses much of the same techniques:

    https://www.ted.com/index.php/talks/will ... orest.html

    Cheers,
    Tim
     
  8. Ojo

    Ojo Junior Member

    Joined:
    Sep 6, 2007
    Messages:
    490
    Likes Received:
    0
    Trophy Points:
    0

Share This Page

-->