Story of the Bogs - Part 1 - with John Feehan

00:12:51
https://www.youtube.com/watch?v=XWtni9mbzzg

Résumé

TLDRTwo centuries ago, bogs covered a significant portion of Ireland, providing fuel in a country that had lost most of its forests. Due to large-scale industrial harvesting, the majority of these boglands have disappeared, leaving only smaller, fragmented bogs. Conservation efforts emphasize the importance of preserving these remnants and focus on restorative actions for degraded peatlands to revive biodiversity and their role in carbon sequestration. Historically, these bogs formed post-glacial periods from waterlogged, anaerobic conditions, forming various strata of peat over millennia. Today, efforts are aimed at understanding their ecological narrative from inception to exploitation, aiming to restore ecological richness and sustainability.

A retenir

  • 🌍 Two centuries ago, bogs covered much of Ireland as a crucial fuel source.
  • 📉 Industrial peat harvesting has drastically reduced these boglands.
  • 🌿 Restoring biodiversity and carbon sequestration in bogs is crucial now.
  • 🏞️ Bogs formed over millennia in post-glacial Ireland.
  • 🔍 Small remaining fragments of bogs are vital for conservation.
  • 🏗️ Historical peat was replaced with clay for brick-making in some areas.
  • 🌱 Essential restoration work focuses on degraded peatlands' biodiversity.
  • 🔄 Understanding peatlands' past helps guide future restoration efforts.
  • 🧪 Bogs support unique ecological systems under restoration focus.
  • 🔎 Fine marl deposits under peat provide evidence of bog origins.

Chronologie

  • 00:00:00 - 00:05:00

    Two centuries ago, a quarter of Ireland was covered with bogs, important for fuel due to deforestation. Now, most are gone, leaving few fragments. The focus is on conserving and restoring these peatlands, vital for biodiversity and carbon sequestration. The video series explores the history, degradation, and restoration possibilities of these bogs.

  • 00:05:00 - 00:12:51

    As the ice age ended, a major lake formed and eventually transformed into peatlands through a series of stages involving vegetation in lakes and deposits of marl. The video details these developments, including marl formation with limey skeletons and diverse freshwater species, leading to peat formation. Further, an older clay composes bricks used in Offaly's architecture, highlighting the resource use by humans over the centuries. Future topics will explore further peatland use and restoration.

Carte mentale

Vidéo Q&R

  • What happened to the boglands in Ireland?

    Most have disappeared due to industrial harvesting, leaving only small fragments behind.

  • Why are peatlands important in Ireland?

    They were a vital source of fuel in a country that had lost most of its woods.

  • What is being done to restore the peatlands?

    Efforts are focused on conservation and restoring degraded peatlands to enhance biodiversity and carbon sequestration.

  • How did peatlands originally form in Ireland?

    Peatlands formed from organic soil build-up in waterlogged conditions post-glacial period, evolving over thousands of years.

  • What is marl, and how does it relate to peatlands?

    Marl is a limey deposit found under peatlands, formed from ancient lake vegetation remains. It serves as a basis for peat development.

  • What challenges do current restoration efforts face?

    Restoration aims to recover biodiversity and carbon capture abilities, despite significant degradation of peat reserves.

  • How deep were historical bogs in Ireland?

    Some were underlying up to 15 meters deep.

  • What historical impact did the loss of bogs have?

    The industrial harvesting severely reduced peat reserves, impacting fuel availability and the natural environment.

  • What were bogs replaced with in terms of usage?

    Parts of peatlands were used for making bricks, exploiting deeper geological clay deposits.

  • What is the future goal for raised bog restoration?

    To restore as much biodiversity and carbon sequestration ability as possible.

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Sous-titres
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  • 00:00:02
    two centuries ago
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    one in every four or five hectares of
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    land in ireland
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    was covered by bog a wild
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    and wonderful type of landscape
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    underlying by anything up to
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    15 meters of peace a very limited
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    agricultural value
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    but a vital source of fuel in a country
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    that had lost
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    almost all of its woods between the 16th
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    and the 19th century now
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    almost all of that has disappeared
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    mostly as a result of large-scale
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    industrial harvesting of peat and all
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    we're left with
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    are a few small remnant fragments
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    precious fragments such as this
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    the conservation of which is an
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    important conservation priority
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    but perhaps even more important
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    is the restoration to as
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    great an extent as possible to those
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    now degraded peatlands which have been
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    stripped
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    of their great reserves of peat
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    to a state of biological diversity
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    and to a state where something is
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    restored of their ability to sequester
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    carbon
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    so what we're going to do or try to do
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    in this short series of videos
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    is to tell very briefly the story
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    of the raised bogs of how they came to
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    be here in the first place
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    of how they came to be the wild and
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    wonderful places they once
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    were to tell the brief
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    chapter of how they disappeared and most
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    importantly
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    what we can do to restore as much as is
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    possible
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    of what has been lost
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    towards the end of the ice age 12 or 13
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    000 years ago
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    a great lake formed in the midlands
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    between two melting ice masses
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    that had begun to split apart and were
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    moving away from each other
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    one of them was anchored in place on
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    sleeve bloom to the south
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    and the other was retreating north
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    westwards
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    over time great quantities of sand and
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    gravel
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    carried in melt water streams in tunnels
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    at the base of the ice
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    were washed into this lake and deposited
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    as
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    deltas and fans along the margins of the
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    lake
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    and it is these deposits that in time
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    came to become
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    the winding ridges and waves of the
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    eskers
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    which are such a distinguishing and
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    characteristic feature
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    of the landscape of the midlands
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    the great size of some of the boulders
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    in the eskers gives us some idea of the
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    power
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    of the meltwater rivers flowing beneath
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    the ice
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    elsewhere a more general blanket of
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    mixed rocky debris was dumped on the
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    land
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    rock debris that had been entombed in
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    the moving glaciers and left behind when
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    the retreating ice finally melted
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    when the ice had all melted away a
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    network of lakes replaced the one great
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    lake of the late glacial period
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    then when conditions became warm enough
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    for life to return
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    the lakes were colonized by vegetation
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    and animal life
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    and it was these lakes that over the
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    course of time became the templates
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    for the formation of peat peat
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    is an organic soil that forms where
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    conditions are waterlogged
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    and therefore anaerobic inhibiting
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    decomposition of dead plant material
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    which therefore builds up over time
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    where the many meters of peat have been
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    stripped away from the bogs
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    we can see with our own eyes and examine
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    the evidence
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    for this first chapter in the story of
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    the bogs
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    so this is what we find underneath all
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    those many meters of peat
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    this white limey deposit which is known
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    as marl
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    and the marble is made up largely of the
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    remains of the plants that were growing
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    at the bottom of these
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    early post-glacial lakes particularly
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    stonewarts
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    which have a limey skeleton and in fact
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    there are still some stonewarts actually
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    growing in the drain
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    here are some so
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    the limey skeletons of these building up
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    year by year
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    is what largely went to the composition
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    of the marl
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    and if we examine the mild more closely
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    we can see that it also contains
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    numerous remains of lots of different
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    species of freshwater snails
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    many of them similar to species that are
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    found in limestone lakes in the midlands
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    today
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    and others which have since disappeared
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    from ireland
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    so that's the mall and sometimes in some
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    places
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    the mile can accumulate or has
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    accumulated to a depth of several meters
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    and if we take a look now at what is on
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    top of the mall what comes immediately
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    after the marl
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    you can see this is the lowest piece
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    here okay the lowest pin it will take
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    take some of that away
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    and have a look at that
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    because it's very crumbly and
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    it breaks into kind of flat plate like
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    bits
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    this is reed swamp or reed marsh
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    peat and it's made up largely
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    of the remains of reeds
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    that were growing on the margins of the
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    lake and if you look
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    more closely you can actually still see
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    the flattened remains of the leaf stems
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    you see how easy it breaks because it's
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    breaking parallel
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    to those flat
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    stems of the reeds
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    so those are flattened reed stems
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    basically that's a good example see
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    okay so that's reed swamp peat and again
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    in some places
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    that reed marsh reed swamp pete can
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    accumulate to a depth of several meters
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    then on top of that
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    here it's not as deep as that it's maybe
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    two-thirds of a meter here but on top of
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    that you'll see
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    the peat
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    becomes much more crumbly
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    becomes much more crumbly there are no
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    reed stems in this but there are present
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    are little twigs
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    you see bits of twigs present here that
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    and if you look at those more closely
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    those little twigs are going to be
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    mainly birch or alder
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    this is this crumbly black peat is fen
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    peat
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    which accumulated as the advance of the
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    reed marsh into the lake squeezed out
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    the open water all together
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    and conditions became suitable for a a
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    woody
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    swamp-like habitat in which this
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    thin piece accumulated again for many
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    hundreds of years
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    over the course of time then the reeds
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    extended further and further out into
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    the deeper waters of the lake
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    giving rise to large areas of reed swamp
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    eventually squeezing the open water out
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    altogether and accumulating
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    as reed swamp peat sometimes to a depth
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    of several meters
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    although the plants growing in these new
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    fen habitats had an abundant supply of
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    minerals
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    limited soil aeration and water-logged
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    conditions continue to inhibit
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    decomposition
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    resulting in continued peat formation
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    but in time the growing thickness of
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    peat
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    raised the surface beyond the reach of
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    groundwater and its nutrient supply
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    giving the advantage to new communities
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    of plants that could thrive without that
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    source of nutrients
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    these communities of bog plants now
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    replaced those of the fen
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    plants that had evolved a variety of
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    different strategies which enable them
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    to survive
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    independently of groundwater nutrients
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    the marl here can be as much as several
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    meters deep
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    but down below the marl there is often
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    an
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    older and very different sort of clay
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    this older clay formed in the great lake
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    that lay across the midlands towards the
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    end of the ice age
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    the same lake into which the sands and
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    gravels of the eskers were swept
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    and deposited along the margins long
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    before
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    conditions became warm enough for any
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    vegetation to grow
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    or for the marl to form
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    but this was the finest sediment
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    which drifted out into the deeper waters
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    of that great lake
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    where it settled slowly year by year
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    forming a finely laminated clay each
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    narrow band recording a single year of
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    seasonal deposition
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    this older clay which is very dense and
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    heavy
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    sticky in texture and blue gray in color
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    is the material from which the yellow
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    bricks that are such a distinctive
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    feature of offaly's architecture were
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    made
  • 00:10:39
    from the 17th century onward
  • 00:10:46
    in the 19th and early 20th centuries
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    bricks from this clay
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    were made on a modestly industrial scale
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    along the brosnan and its claudia
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    tributary
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    where the same blue grey late glacial
  • 00:10:58
    play occurs extensively under the
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    callows
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    but they were made on a smaller scale
  • 00:11:03
    from clay under the bog in many
  • 00:11:04
    localities
  • 00:11:08
    the bricks were made by hand one by one
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    using timber molds
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    and since the kiln in which they were
  • 00:11:14
    burnt was made of the bricks themselves
  • 00:11:16
    nothing remains at the site of these
  • 00:11:18
    kilns today but the telltale signs of
  • 00:11:20
    scattered broken brick
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    they were especially fashionable for
  • 00:11:25
    framing windows and doors
  • 00:11:28
    but in areas close to the bogs entire
  • 00:11:31
    houses were often made of brick
  • 00:11:32
    and rough stone from the glacial moraine
  • 00:11:44
    this brief look at how the bogs came to
  • 00:11:46
    be here in the first place
  • 00:11:48
    is the first part of a tree act drama
  • 00:11:53
    which is the story of the raised bogs
  • 00:11:56
    in the second act we will look at how
  • 00:11:58
    the bogs grew to be the wild and
  • 00:12:00
    wonderful places they once were
  • 00:12:02
    and at how they disappeared as we
  • 00:12:05
    exploited their great reserves of peat
  • 00:12:07
    for
  • 00:12:08
    energy for fuel and for horticultural
  • 00:12:11
    use
  • 00:12:13
    in the third act we will look to the
  • 00:12:16
    future
  • 00:12:17
    at what we need to do in particular
  • 00:12:21
    uh to restore to these now degraded
  • 00:12:23
    areas of peatland
  • 00:12:25
    that have been stripped of their great
  • 00:12:27
    reserves of peat
  • 00:12:28
    of as much as we can of their lost
  • 00:12:30
    biological diversity
  • 00:12:32
    and their ability to sequester carbon
  • 00:12:51
    you
Tags
  • Bogs
  • Peatlands
  • Restoration
  • Ireland
  • Conservation
  • Biodiversity
  • Carbon Sequestration
  • Industrial Harvesting
  • Ecology
  • Historical Geology