Seed Dispersal and Forest Fragmentation | HHMI BioInteractive Video

Seed Dispersal and Forest Fragmentation | HHMI BioInteractive Video


[INSECTS CHIRPING] [MUSIC PLAYING] SPEAKER 1: The tropical
forests of Colombia are home to a myriad of
plant and animal species. Like many of the
world’s forests, this one in the Middle Magdalena
Valley is also under threat. As Colombia’s human population
grows, huge swaths of forest are cleared for farmland
and cattle ranches. The remaining patches
of forest become fewer and further apart from each
other, in a process ecologists call habitat fragmentation. Fragmentation
threatens the survival of all animals that
live in the forest, by reducing the
amount of habitat. And converting what’s left to
patchy, disconnected areas. That is particularly
true for the largest primate in the Americas–
the brown spider monkey. They rely on trees for
their food and shelter. And a continuous forest
canopy acts as a highway, providing them the
freedom to move. ANDRES LINK: The situation
with brown spider monkeys in Colombia, is
very, very critical. They’ve lost more than
80% of their forests. SPEAKER 1: It’s clear
that spider monkeys rely on forests to survive,
but do the forests also rely on spider monkeys? [MUSIC PLAYING] Wind, water, or animals can
carry seeds from a parent plant to new locations. The seeds of
tropical tree species are primarily dispersed by
animals that eat fruits. SPEAKER 2: Many animals eat
hundreds and hundreds, if not thousands, of fruits in a day. Most of them will
swallow the seeds and will defecate
them in other places. And through this
process, disperse them in different parts
of the forest. SPEAKER 1: Spider monkeys
eat large amounts of fruits to support their size. And are likely, a major seed
disperser in Colombian forests. When seeds simply
fall in the forest, they end up near
their parent tree. Here, seeds compete with other
seeds from the same tree. Their chances of
survival are low, but seeds that are carried
away by spider monkeys and other dispensers are more
likely to survive and grow into a healthy plant. Fragmentation reduces forest
regeneration in two ways. It decreases the number
of seed dispensers. And it limits how far
they can safely travel. Andres Link and
his colleagues have come to the middle
Magdalena Valley to measure how many seeds
spider monkeys are dispersing. And from which tree species. ANDRES LINK: So we
started to wonder, what is the role of these
primates in the dispersal of seeds of many plant species? CAROLINA URBINA MALO: They
help to regenerate the forest, and it’s very important to know
which species are they eating because in that way, we
know which species are going to spread and which are not. SPEAKER 1: The first
step is to collect the seeds dispersed by an
individual monkey in a day. SPEAKER 2: And what
we do, literally, is to follow them
the whole day long. We see that they’re
going to defecate, and we pay close attention. But also, normally we
hear that some seeds fell that a monkey defecated. Then you can hear it,
how it sounds when it hits the leaves and the ground. But when we can’t
find it, what we do is that we rely on those animals
that are specialists in getting to these fecal samples. We just have to
stay really still. A couple of seconds,
you’ll start hearing some buzzing
that increases and increases in sound. CAROLINA URBINA MALO:
The dung beetles have a very particular sound. So you will follow the sound,
look for that dung beetle. And they will be making a
little bowl from the poop that you want. So you will just take it. SPEAKER 2: So we have some
dung beetles here collecting the poop. So there must be seeds around. And we can find something here. We collect each fecal sample
in an individual plastic bag. And we put an individual
number to each bag because we’re interested
in quantifying, not only seed dispersal
of the species, but also the ability
of each individual. Or the amount of seeds that it
can disperse in a single day. Or to find difference
between males and females or. In matures and mature animals. A single spider monkey
can defecate, probably, between 13 and 17 times a day. And this is only one monkey. And these will represent 100,
if not thousands, of seeds that a single monkey
disperses in this forest. SPEAKER 1: They clean
the seeds they’ve extracted so they can be further
characterized and cataloged. This work takes place back
in their lab, in Bogota. ANDRES LINK: In the
Middle Magdalena, these spider monkeys can
disperse about 100 species or maybe more. As we learn about the
important role of spider monkey seen in dispersing
the seeds of many plants. And at the same time, we see
how populations are declining. We start to worry a lot about
the future of these forests. SPEAKER 1: With
fewer spider monkeys, the forest is less
able to regenerate, further decreasing the
spider monkeys habitat. Researchers are trying to
break this cycle by replanting the seeds they found. They plant them in
deforested areas that are no longer
used for agriculture. They will grow into
the trees that monkeys need for food and shelter. ANDRES LINK: So what we do is
that we collect those seeds, and we plant them in areas
that have been degraded. Especially, we
planned them in areas that we have
identified that can be potential corridors between
isolated patches of forest. SPEAKER 1: Growing these trees
in the areas between forest patches will allow spider
monkeys to move from one patch to another, increasing both
their chances of survival and their ability
to disperse seeds. ANDRES LINK: We really think
this process of restoration and connecting these forests
will provide a future scenario that is much nicer. A future scenario
in which monkeys will not depend on us to
have a viable population going on there and
surviving without the need of our assistance.

7 thoughts on “Seed Dispersal and Forest Fragmentation | HHMI BioInteractive Video

  1. A critical topic to understand forest dynamics, very well explained and illustrated. Very happy to notice the narrator's native language is Spanish, shows great pronunciation of terms and names.

  2. In Malaysia,many forests belong to the rich people for logging, mining and everything. I studied gibbons but so hard to convince them to replant the forest. for them, development is more important than conservation as development will give profit in return (factories etc.) and forest brings nothing to them.

    It is amazing how your work is done successfully hoping that my country will follow. It's good to know how you communicate to the society about this. If you don't mind to share.

  3. This video is GREAT!!!!! It really helped me out in my biology class. You just gained a subscriber. Keep up the good work.

  4. This is a great video and helps students see real-world connections. However, the narrator speaks too fast for many of my students to understand and grasp what is being said. SLOW DOWN!

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