Tag Archives: Pinus contorta

A long migration

5000 years ago, Native Americans in what is now the southern US created an extraordinary earthwork: Watson Brake took centuries to build and is the oldest mound complex we know about in North America.

We don’t know what it was called or what it meant to its builders; things that happened 5000 years ago are hard to reconstruct. But we try anyway.

While the creators of Watson Brake were mixing their fish bones into the mounds in Louisiana, the eastern edge of the lodgepole pine migration front was crossing the Yukon Plateau 4000 km away. By the time the last handfuls of soil were being packed onto Watson Brake’s 25 foot tall ridges, lodgepole had hit the high, cold teeth of the Selwyn and Pelly Mountain ranges.

Photo by Ed Struzik of Cirque of the Unclimbables (actually in the Mackenzie Mountains to the east of the Selwyns)

The trees couldn’t cross the high mountains, but they followed the Frances River through a pass just 20 km wide to Frances Lake in southeastern Yukon.

Frances Lake with Logan Mountains in the back. From Frances Lake Wilderness Lodge

4000 years ago the vizier to Pharaoh Mentuhotep IV led an expedition to Wadi Hammamat where he gave offerings to Min, a fertility god. A few years later, Mentuhotep was dead, childless, and the vizier was Pharaoh. He probably didn’t kill Mentuhotep, but that was 4000 years ago, so who knows?

About the same time Amenemhat was maybe-but-probably-not thinking about usurping the throne of ancient Egypt, lodgepole pushed out of Frances Lake’s narrow valley. Freed from the confines of the high mountains, lodgepole began a slow march up the the Tintina Trench.

The Tintina trench and its extension, the Northern Rocky Mountain Trench, are a longstanding human travel route and geological marvel. I wonder if the trees followed the people or the people followed the trees?

When the first Roman Emperor died, the eastern edge of the lodgepole migration front rounded the top edge of the Pelly Mountains at Pelly Crossing and sprawled across the eastern portions of the Yukon River watershed, down to meet the western migration front slowly making its way through the valleys of the northern Coast Range.

Pelly Crossing. Bridge not available for use by trees.

But lodgepole kept going up the Tintina Trench, too. Today, they’re are all the way up to Dawson. It’s not clear exactly when they got there, but the Tr’ondëk Hwëch’in have definitely been there longer than lodgepole has.

People move so much faster than trees that we don’t always notice their incredible journeys. But journey they do!

From Strong & Hills in The Holocene, 2013

If you want the details and a discussion of uncertainty around these estimates, check out the paper: Strong, W. L., & Hills, L. V. (2013). Holocene migration of lodgepole pine (Pinus contorta var. latifolia) in southern Yukon, Canada. The Holocene, 23(9), 1340–1349. http://doi.org/10.1177/0959683613484614

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Pinus contorta distribution map in #rstats

I made a map in R for the first time last week using these guides by Kim Gilbert and Mollie Taylor.

Pinus contorta range map including all subspecies. White areas within the distribution boundary contain no lodgepole. Based on Little 1971.

Pinus contorta range map including all subspecies. White areas within the distribution boundary contain no lodgepole. Based on Little 1971.

As you can see, I wasn’t able to show the holes in the distribution properly. Ideally, they would be actual holes showing the base map. I couldn’t get geom_map to not fill in the holes, so I overfilled them with white.

The code for the map is below and the shapefile I used is from the USGS GECSC Tree Species Distribution Maps for North America.

If anyone’s got a shapefile for just subspecies latifolia or a more recent distribution map, I’d love to use it.

pcontorta <- readShapePoly("pinucont.shp")
colors <- brewer.pal(9, "BuGn") # make pretty color palette

basemap <- get_map(location = c(lon = -120, lat= 50), #build basemap of Western North America
  color = 'color',
  source = 'google',
  maptype = 'terrain',
  zoom = 4)
basemap <- ggmap(basemap)

pcontorta.points <- fortify(pcontorta) 

lodgepole <- geom_map(inherit.aes = FALSE, #make a layer for the lodgepole distribution
  fill = colors[9],
  alpha = .5 )

holes <- geom_map(inherit.aes = FALSE, #fill the holes with white
  data = pcontorta.points[which(pcontorta.points$hole==TRUE),],
  fill = "#FFFFFF",
  alpha = 1 )

basemap + lodgepole + holes + #put it all together
xlab("Longitude") + ylab("Latitude") +
ggtitle("Lodgepole Pine distribution") 
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Joining the National Phenology Network to help me with my PhD

As part of my PhD, I want to predict when lodgepole pine releases pollen and when its seed cones are receptive across as much of the species range as I can. I’m using data collected in seed orchards (thanks Joe Webber, Chris Walsh, Rita Wagner, and the countless people who were part of building these data sets) to build a model, and I’d like to use citizen science data from the National Phenology Network to test my model.

Right now, the dataset for lodgepole pine from NPN has observations for 28 individuals at 6 sites over about 2 months in 2 years. I’d like more sites, more individuals, and more years to test my model against. I’m going to be tracking down as many lodgepole pine populations as I can around Vancouver and keeping track of them in my own Nature’s Notebook.

You could help!

NPN has pretty fantastic data sets from a lot of awesome volunteers. You can be awesome, too: pick your favorite species and start collecting data! It will make you look really important when you’re out hiking and provides a great excuse for that time your neighbor catches you in their yard right next to their lovely camellias.

Of course, I hope all you western North Americans choose to start collecting data on lodgepole pine. How could you resist these lovely little pollen cones?

Pinus contorta male strobili/pollen cones. Photo by Sally Aitken

Pinus contorta male strobili/pollen cones. Photo by Sally Aitken

If you’ve never had a close look at pollen cones, here are some nice pictures summarizing the stages the cones go through from a report by John Owens:1

Figure from Owens 2006

Figure from Owens 2006.

If you give me a year and a location, I want to be able to tell you when stages 3 and 4 happened. Stay tuned for results!
1. Owens JN: The Reproductive Biology of Lodgepole Pine. Forest Genetics Council of British Columbia; 2006.

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