Siberia 2012: Long Day in the Larch

July 11th, 2012 by Joanne Howl
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Embenchime River  66  N  97 E

9:15 a.m. local, 9:15 p.m. EDT

70°F high   53°F low   rainy with gusting wind

Dr. Ranson Reports:

This evening I have to admit – I am tired.  I was out of my tent and working around camp by 7:30 this morning.  We reached our field sites about 11, and worked making measurements until after 7 in the evening.  It was a good day’s work, and great to be back out in the field.

At the end of the day, we had collected data from 22 plots – a full day.  And yes, we trampled across Papa Moose’s territorial line.  Fortunately, he graciously decided to leave us alone.

The morning began with paperwork in camp beside the Embenchime. Sergei (left) is entering GPS points. Ross (left) is checking out the plot sampling plan. Slava (center) is updating his expedition journal. Note the rocky soil – this is the same type of ground that the tents sit on – and on which the scientists sleep.

It was chilly overnight, and the morning was cloudy, with winds from the northwest that carried promises of rain.  By the afternoon, it the rain and wind had arrived. It wasn’t all that bad – we still were able to work – and this region needs rain.

The cool, rainy weather, however, seemed to cause Slava some pain.  He had hurt his back earlier in the week, but it hasn’t been troubling him too much. This morning, however, he decided it was wise to rest a day in camp.  We divided up into two teams: Ross, Sergei and Guoqing formed one group, and Pasha and I made up the other group.  The three man team was able to measure 12 plots, and my two-man team measured 10.  That’s a pretty good day’s work in these rugged lands.

Today we concentrated on sites where the GLAS instrument on the ICESat satellite has already acquired data.  This will help us correlate that data with the truth on the ground.  To get to a site, we plug the coordinates into our handheld GPS, then follow the GPS instructions to that point.  We then locate the center of that plot, as closely as possible.  Because there can be error in GPS, we then take out a more sophisticated GPS – a standing model with a large antenna – and double check our central coordinates. The handhelds gave us very good correlation with the fancier model.

Once we identify our sample plot, we make a set of very standard measurements and observations.  For each tree, we write down the species (all larch here) then measure the dbh, or the diameter of the trunk at breast height.  Then we choose a few trees in each plot and measure their height.  We’re using a basic inclinometer to find height.  To do this, we stand away from the tree, measure the distance from us to the trunk, then sight along this instrument to the top of the tree.  The inclinometer gives us the angle formed by the line from the top of the tree to the horizon.   We write that angle down.  Later we’ll break out calculators and derive the height of the tree.  It’s all triangles – simple stuff.  We find the length of one side of our imaginary triangle, and two angles (a right angle between the trunk and the ground, and the inclinometer angle). With two angles and one side, we can easily calculate the other sides of the triangle – and the height of the tree – no computers required.

In each plot, we find every tree over 5 cm in diameter to note species and dbh.  We also observe the understory and note what is found there – lichen, moss, sedges, shrubs or rock. These observations help us understand the reflectance properties of the forest floor.  When we look at the data acquired from space, this information will help us reduce the noise of the data, by removing the background reflectance.

It is very important for the scientists to make detailed notes about the ground cover in each study plot. Here, the understory on the left is primarily lichen. To the right, both Vaccinium (blueberries) and Betula nana (dwarf birch) grow. Each of these ground covers will reflect light different, and therefore should look very different from space. The reason for the difference in ground cover is soil mosture. To the left, the soil is dry; that on the right is more moist.

We also measure the shape of the crown of the trees, to help our mathematical models calculate the light reflectance from the crowns.  We measure the width of the crown in two directions, and the depth of the crown.  The depth is the measurement of the live crown from the top of the tree to the lowest live branch.  These measurements will give us the shape of the crown.  The “crown” is where the leaves and the branches are located.  Then, with statistical distributions, we can calculate how much of the larch canopy consists of leaf, and how much is branches.  All of this goes into our models to help us understand the reflectance characteristics of the crown of the trees in the forest.  It all helps us understand what a satellite would see from space.

We use these measurements to make better instruments, and to better understand the data we already have acquired.  Our driving question, of course, is to find out how much carbon is held by these forests, and carbon storage correlates strongly with biomass.  Because most of the biomass is contained in the tree trunks, we can get good idea of the of a tree biomass if we know the tree diameter and height. We can do that simply by measuring, here on the ground.

But forests are just too vast to personally measure each tree.  To know about the forests, we look to remote sensing – to instruments carried by satellites or aircraft – to collect data for us.  And that’s where it gets complicated.  Such instruments collect a lot of data, and we have to know a lot about things like the reflectance of the background and the canopy to sort out the noise from the useful information.  Maybe it all sounds all very complicated, but this is really critical – being able to sort out the noise from the trees is very fundamental science that is required in order to understand the biomass in the forest.

The GLAS plots run in straight lines, one every 172 meters.  When we finish with one plot, we load the coordinates of the next into the GPS, and walk 172 meters in that direction, and start the process all over again.

What we’ve found today is that there is great variability in the trees in each plot.  One plot had a total of six trees in it.  Another had 64 trees.  Based on our observations, it appears that the growth of the larch here is controlled by soil moisture.  Where conditions were dry, the trees appeared bigger and further apart.  If it was moist, they were closer together and smaller.

We saw one area where there were large trees mixed with a stand of smaller trees.  The large trees seemed to be in decline.   The smaller trees were all about the same age, and growing fairly thickly.  The impression is that a fire may have come through here several years ago, and damaged the older trees enough that they are slowly failing, and at the same time, the fire spurred regeneration.

Fire is a strong stimulant of larch regeneration.  It causes the cones to open, allowing for re-seeding. And fire provides the right conditions in the soil to enhance germination of larch seeds.  Larch has been called a “pyrophytic” tree – that means fire-loving.   That may be a little strong – because larch stands certainly can be burned to the ground by hot crown fires.  But once the fire has passed, you do see intense regeneration of larch – sometimes several thousand larch saplings growing in just a hectare.  Not all of these will live, of course, but the fire-induced reproductive effort is quite strong.

When we returned to camp, we heard that Slava had a little adventure today.  Every time we make camp, we set up a big tent.  It’s tall, so we can stand up in it.  We use it for storage and to protect of our gear, and sometimes we use it as an office.  To hold our tents down, we just tie them to rocks, because you can’t drive tent pegs into pure rocks. Normally, this works fine.  Today, as the rains began, a big gust of wind came up.  It caught our big tent, lofting it up and sending it down river.  Slava gave chase, and managed to catch it and drag it back to camp.  When we arrived, all was in good order, although our fine big tent was now VERY heavily weighted down with rocks. We’re grateful Slava needed to rest his back – I don’t know if he got any rest, but he did save our tent.

Pasha (left) and Guoqing (right) enjoy a fine lunch in the field. The primary components are canned fish, ikra (a canned veggie paste), and for desert, a candy bar.

We had plenty to eat again.  Oatmeal for breakfast, and a portable lunch of canned fish and ikra – that’s a canned vegetable paste that seems popular in Russia – and a Snicker’s bar.   For dinner, it was fish soup.  We are eating a lot of protein, with some high-fiber carbs and not too much sugar.  I feel like I’m losing weight already, and I look forward to winning Ross’ little weight loss challenge with me.  Hmmmm…. I wonder if Ross ate his Snicker’s bar, too?

We’re looking forward to another day’s worth of work at this campsite tomorrow.  We have several more plots, so we’ll probably spend another night here before moving down river.  The final decision, however, will be deferred until tomorrow afternoon.  If we get done in time, we’ll move on tomorrow evening.  If not, we’ll eat fish soup and sleep.

 

One Response to “Siberia 2012: Long Day in the Larch”

  1. Wm. Glesener says:

    If you can figure out the distance you need to be from the tree so that the reading equals the height (rather than doing the math) its a simple horizontal measurement to get the tree heights directly from the clinometer readings. In the US we use the 66′ type so we only need to be 66′ from the tree and can measure the heights directly.

    If you’re stuck with metric ones, do the math ahead of time to see what the distance from the tree is to record direct heights from the clinometer. (Top shot minus bottom shot equals total height).

    But you already probably knew that.