Monday, April 3, 2017

Urban reforestation

Last week I got to do something I’ve fantasized about for years—urban reforestation.

Our organization here in West Kalimantan does a lot of reforestation work in Gunung Palung National Park.  We plant native rainforest seedlings in areas that are important for wildlife but have been illegally cleared for timber or farmland. One site is in a hilly area that was clearcut and then burned repeatedly until the forest was replaced by man-made grassland.  Another site is a peat swamp that was cleared to make rice paddies.  And earlier this year we planted on land recovering from years of use for farms and plantations.

But our newest challenge may be the most difficult yet.  We’re working to restore 0.5 hectares of urban landscape to native rainforest.

Our newest reforestation effort targets narrow belts of land around a private clinic

The land in question has a long history of abuse by humans.  It was farmed for years, and some small buildings were built on it.  Then in 2006 the vegetation was completely destroyed by a human-caused wildfire, paving the way for the plot’s invasion by invasive Acacia mangium trees.  After nearly a decade of regrowth the vegetation was again completely destroyed, this time by bulldozers.  Construction workers followed the bulldozers, covering some of the site in gravel and concrete, and using the rest as a dump.   The land today is covered in scraps of sheet metal, cans of paint and chemicals, and other garbage, much of which has been burned to form twisted piles of toxic ash and melted plastic.  There are even the ruins of an outhouse, the concrete toilet holes now filled with sand.

The land has been severely degraded by human activities, and many areas are now covered in concrete or trash

For years this land has been valued only for what people could get out of it, put on it, or dump in it, and we’re trying to change that.  If left alone this land could once again become valuable rainforest, and we want to ensure that happens.

To that end, last week we planted nine hundred seedlings of around fifteen native species.   What’s more, we turned our reforestation vision into an educational opportunity by inviting local teenagers to help.  Around 20 students volunteered after school to prepare the site and plant seedlings.

Teenagers from our conservation education programs volunteered to help plant native seedlings…

…and so did nurses, doctors, and other clinic staff

Although this project is relatively small—900 trees on ~0.5 hectares—it could have a huge impact.  It’s in a critical area bordering the national park and surrounded by rapid development.  The newly planted land will serve as a corridor that extends the park’s forest an extra 400 meters to a nearby road.  Just two years ago red leaf monkeys (Presbytis rubicunda) and silvery lutungs (Trachypithecus cristatus) could be seen from the roadside.  Then the land was bulldozed, new homes and businesses popped up nearby, and the monkeys disappeared.  The most commonly seen animals today are foreign invaders like tropical fire ants (Solenopsis geminata) and Eurasian tree sparrows (Passer montanus).

By ensuring rainforest once again reaches to the road, we not only hope to return the monkeys and other native species, but also keep wildlife populations on either side from becoming isolated by development.

We hope to create a narrow belt of forest extending all the way to the roadside to prevent development from fragmenting wildlife populations

The urban conditions are challenging for the seedlings—planted in compacted gravel or among concrete building foundations, exposed to fierce sunlight, and drawing nutrients from soil polluted by chemicals, metals and burned plastic—and we expect fewer to survive than normal.  But we’re optimistic.  Rainforests have thrived here for tens of thousands of years, and they can do so again if we let them.

I can't wait to see how these seedlings look in a few years.

Tuesday, February 14, 2017

Virtual fire ants

Last month I published my first computer modeling paper.  I understand the power and value of simulation studies, but I’m not usually a fan of them.  I tend instead to do projects that involve field experiments, collecting specimens, or measuring things in a lab.  But after years of collecting data on dozens of real-life ant species, I thought I had enough information to create a realistic virtual one.

A computer simulation would allow us to test ideas that would be difficult or impossible to test in real life.  We could, for example, build a virtual ant population and watch it evolve over generations.  And we could do that repeatedly with many populations at the same time.  In just a few days we could have 25 virtual years of data from hundreds of simulated worlds.  Getting the same information in the field could take a whole career.

So we got to work designing virtual ants.  We made a program that created worlds inhabited by ant colonies whose properties we could tailor as we saw fit.  We could then see how tweaking the biology of ant colonies—how they grew, died, and reproduced—affected their populations.

Our program followed ant colonies over several generations as they were founded, grew, acquired territory, reproduced, and died (figure adapted from Helms & Bridge 2017)

Our ant of choice was the red imported fire ant (Solenopsis invicta).  We chose to work with fire ants for three reasons.

1) We know a lot about them.  Programming a realistic animal requires a lot of information, and fire ants are perhaps the most studied ant on the planet.  We have detailed field measurements of how and when they reproduce, how colonies grow and compete for space, and how long they live.

2) They are important.  Fire ants are an invasive species in the US and elsewhere.  Farmers, governments, and conservation organizations around the world want to know how they spread.

Fire ants were accidentally introduced to Alabama in the 1930s and have since spread throughout the southern US (figure from Calcott & Collins 1996, The Florida Entomologist)

3) They are interesting.  Fire ants are a model system for studying alternate reproductive strategies.  They have a complicated life history and reproduce in several ways.  Colonies produce queens that fly off and found new colonies in vacant soil, but they also produce parasitic queens that take over other colonies of the same species.  So by studying them we could learn how parasitic ants evolve, and how the evolution of parasitism affects other aspects of their biology.  (Fire ants have plenty of other odd twists in their biology as well, but for this study we focused on parasitism)

Fire ant colonies practice two reproductive strategies—they produce some queens that found new colonies and other, parasitic, queens that take over existing colonies whose previous queens have died

Once we had our program and our virtual ants, we ran a couple experiments.  In the first, we set up different ant populations that varied in how colonies reproduced.  In some populations colonies only produced queens that founded new colonies, whereas in others half the queens produced by colonies were parasites, and other populations fell somewhere in between.  We then tested whether producing parasitic queens affected the demographics of populations—how large or how spread out the colonies were.

In our second experiment we created mixed populations inhabited by several lineages of ants.  Some lineages produced lots of parasitic queens and others didn’t.  We then watched the populations evolve over time as some lineages survived and reproduced more effectively than others.

We found that populations that produced more parasitic queens had larger colonies and occupied more of the available habitat.  Populations that don’t produce any parasitic queens, on the other hand, spread faster.  This is because parasitic queens can only take over existing colonies—they can only survive in areas already occupied by fire ants.  But queens that found new colonies can survive anywhere that isn’t already claimed by an existing colony.

When it comes to evolution, it turns out that location plays a deciding role in which strategy is favored by natural selection.  Populations at the edge of an expanding range, which are surrounded by suitable empty habitat just waiting to be colonized, evolved to produce almost no parasitic queens.  Conditions are nearly opposite in the interior of the range, which is saturated with existing colonies and contains little free space in which to found new ones.  Not surprisingly, populations in those areas evolved to produce more parasitic queens.

No computer model is supposed to be entirely accurate.  Models are instead meant to be useful for teasing apart how different factors influence a process.  What we need now is a field study to see whether we see the same patterns in nature that we do in our model.  That’s a project for another day…

So while a computer simulation was way outside my comfort zone, it did have one thing in common with all good research—it raised just as many questions as it answered.

Saturday, January 14, 2017

How to start an ant lab in the rural tropics

Borneo is one of the most important areas in the world for urgent ant exploration.  It is home to a high number of ant genera, is estimated to contain hundreds of undescribed species, and is under extreme conservation threat, with over half its land area cleared for farmland in just the past few decades.

But we still know little about the ants of Indonesian Borneo.  Most ant research in Borneo occurs in Malaysia or Brunei—the two countries that share the island with Indonesia—even though they cover only a small minority of its land area.  As far as ants are concerned, the three fourths of the island that happen to fall on the Indonesian side of the border are pretty much a blank spot.

So for the past few months I’ve been setting up a lab here in Sukadana, making us the only hub of ant work for hundreds of miles in any direction.  But starting a lab in rural conditions in the wet tropics required a bit of improvising.

Getting ethanol, for example, is almost impossible.  There is a medical supply store in the provincial capital of Pontianak, a 4 to 5 hour boat journey away through the winding Kapuas River delta.  But even they don’t sell ethanol.  Ethanol must be special ordered in Jakarta, shipped overseas to Borneo, and transported to Sukadana by riverboat.  This complex supply chain drives the cost up to a staggering forty US dollars per liter.

Stymied by geography and economics, we are forced instead to preserve specimens in rubbing alcohol, which is available in Pontianak.  Even that takes time, with the alcohol arriving by riverboat a few weeks after ordering.

To collect data in support of our conservation work, I’ve set up an ant lab in Indonesian Borneo

I brought some basic equipment with me from the US—microscope, lamp and bulbs, forceps and insect pins.  But much of the rest of our gear is pieced together from supplies available at local hardware or grocery stores.

I built a litter sifter, for example, out of two paint trays, some wire mesh, duct tape, epoxy and a can of spray paint.

I made a litter sifter to sort ants and other insects from piles of decaying leaves.  This one consists of two layers—a top one to hold the litter…

...and a lower one, spray painted white, to catch the insects that fall through the mesh.

To find ants inside rotting logs and vegetation, I bought a locally made machete.

To collect ants once we find them, we built pooters out of plastic tubing, rubber bands, and either a thin cloth or soft mesh from a kitchen strainer.

A pooter is a long straw that lets you use lung power to suck up ants, but prevents them from going into your mouth

To store specimens once they’ve been collected, Brian Fisher recommended I use plastic containers with mothballs and a drying agent.  I lined my containers with packing foam that Sara and I used on our move from the US, and sealed it in place with Elmer’s glue.

A plastic container, packing foam, a mothball, and some silica gel make a decent specimen drawer

After collecting and storing ants, the final technical hurdle was finding a way to view them under a microscope.  For this step I adapted a trick I learned at Ant Course in Uganda.  I placed a plastic ball inside a spool of electrical tape, and put a blob of modeling clay on top of the ball.  By sticking the pin in the clay and rotating the ball in its socket, I can view specimens at just about any angle.

A homemade ball-and-socket joint, with a dab of modeling clay or old chewing gum, can be used as a stage for looking at specimens under a microscope

With all our equipment in place, we are finally ready to begin collecting ants.  We’ll start with a couple projects to see how local slash-and-burn farming practices impact ant communities, and how our reforestation efforts help undo the damage.

I can’t wait to see what we find!