The island of Chiloe holds some of the region's last, and
greatest, temperate rainforests (bosques templado-lluviosos). However, little of their
former range still exists as forest, much to the detriment of the whole host of
wonderful endemic creatures (from the 5mm long scorpions to the 3,600 year old Alerce trees) that inhabit them.
I have known about old-growth forest destruction for years,
but being a New Englander, I had never witnessed it firsthand (we cut all our
forests hundreds of years ago!) and it seemed an abstract concept - like
parachuting or actually catching fish while fishing. But I got the point awhile
back. One of the other researchers here, Ariel, who studies mammals here (but
is getting a PhD in biogeochemistry) was preparing a talk for a conference on
Monitos, which he had researched for several years. One of his projects looked
at habitat use in different forests, so he needed to take some pictures of his old
study sites, which he had not visited in two years.
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Argopteron aureipennis, a skipper that only lives in clearings in forests with Quila bamboo, where the males dance for mates - flashing their iridescent gold wings. |
After some difficulty finding the desired site, we walked in
about 15-20 yards into the seemingly intact forest and saw the damage – all
large trees in one area had been cut and they seemed to be clearing the
understory and brush from much of the rest. One small section of old forest was
left as was the section between the road and the cuts.
After surveying the damage we returned and talked to others
at the center about it. Apparently it followed the typical logging routine
here: cut forest away from the road, allowing the area near the road to stand.
Of course, in a few years, that too will either die or be cut – a section of
forest 200m x 20 m is not going to survive. And then the invasives will move in
at the expense of the native plants.
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Ariel surveys the once old-growth forest |
One of the sharpest memories of my first few field days in
Argentina was simply that I knew a good number of the plants. I am not a
botanist but I have a pretty good knowledge of the common New England plants.
And here they were: in Argentina. And then in Peru. And then in the Bahamas.
Even Tierra del Fuego had some old friends: hawkweeds and dandelions popping
out of the sidewalk, daisies in the fields – not to mention the muskrats,
beavers, trout and salmon that have completely demolished almost all of the
wetland ecosystems in the area.
Here in Chile though, it seems worse. On Chiloe, acres upon
acres of Scotch broom turn the countryside yellow, a common forest type is Eucalyptus,
you can get as mired in patches of blackberry
as at home and a maple species (I think it is Norway) is taking over
roadsides. In Santiago it was hardly better: tree-of-heaven (Alanthius) sprouting in any barren place
with the standard set of weedy exotics around it.
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Eucalyptus grove, Argentina |
South America has had a short history of interchange of flora
with North America/Europe/Asia, geologically speaking, of course. Instead, much
of the flora (and fauna) is similar to that of Australia and Africa, as they
were once connected in the supercontinent of Gondwana after the breakup of
Pangea. Nothofagus, the dominant tree
genus in Tierra del Fuego, and common here on Chiloe shows this Gondwanan
distribution well, it occurs in South America, Australia and New Zealand. The
common ferns here, in the genus Blechnum,
are also found in New Zealand. Marsupials radiated in Australia and South
America – now in both they are threatened by human activity – development of
the fragile habitats they inhabit and our introductions: dogs, cats, rats,
plants and more. Were it not for these introductions, the logged areas of Chiloe
would grow back into the standard Chiloe forest (eventually), instead, it turns
into a monoculture of Eucalyptus or a scrub of Scotch broom.
However, let's not carry this pessimism too far. I am firmly
of the belief that over time, many invasives get assimilated into the
community. Of course, we do not know the consequences at the time of older
invasions, in New England, for example: plantain, dandelion, daisy, and many
others, including some that we probably just associate with our region. Will
autumn olive, purple loosestrife, Japanese beetles and gypsy moths integrate
into the communities which they invade or remain hugely damaging species
forever?
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This dung beetle - I think Homocopris torulosus - has increased substantially with development and introductions of cattle/sheep/horses and the massive increase in dung that comes with them. |
Some evidence points to the former. The famous story is the
Brown-tailed Moth, which is probably better known for its horrible sting than
anything else (the caterpillar sends people to the hospital with regularity!).
But it was a huge problem species in New England during the first half of the
20th century – its range extended into every state and was a pest of
many tree/shrub species. Then, rather suddenly, it declined – and now is found
on a few islands in Maine and at the very tip of Cape Cod. Why? One paper claims
that an introduced parasitic fly probably played a big role and the authors did
a very clever experiment to support this by transferring caterpillars to plots
within the former range, which resulted in higher mortality than found in the
remnant range. Other invasives have expanded and then contracted as well: the
Skylark and Mynha in the Pacific northwest, hops in the northeast, Argentine
ants in several places. And others, such as English plantain, have become hosts
for native species (in that case, the Baltimore Checkerspot).
Here in Chiloe, I found one native butterfly,
Butleria elwesi, ovipositing on a
European grass, suggesting that here – where the history with such species is
shorter than in New England (Darwin remarked on the lack of cleared land when
he passed through Chiloe) – adaptation to these exotic species is occurring,
too. In 200 more years, will Eucalyptus trees peek through the canopies of
Nothofagus forests?
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B. elwesi, showing the distinctive underwing pattern. |
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Egg of B. elwesi, on I think, Dactylis sp. |