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A week in the life of a marteloscopist

The morning sky is still pitch black when the alarm goes off. I wake up in a hotel room on a grey busy rainy road in a post-industrial town in southern Luxembourg. Hitting the snooze button is not an option; daylight is scarce in late November and we should really reach the forest at dawn. There is still time for a sad corona-proof breakfast though, that is to be consumed in the hotel room. Crackers, instant coffee, jam, all individually packed in plastic of course. What is good for hygiene is not necessarily good for the environment.

Before sunrise, my colleague and I get to the site of our next marteloscope. The morning fog reduces the visibility to almost nothing, but luckily our memory manages to lead us back to the place we had visited with the local forester a month earlier. Despite the dense undergrowth we had managed to survey the perimeter of the square one-hectare stand in October, but not without cutting much of the regeneration along the borders that were obstructing the view and the functioning of our measurement equipment. A tedious effort, but one less task this week. Last time the foliage was still too dense to measure heights or spot tree microhabitats. Now that most of the leaves have fallen, we can continue the inventory. Yesterday we were still in the far north of this little country, to finish precisely those tasks for the previous site. Now we are ready to wrap up the inventory of the final marteloscope in Luxembourg.

The warm glow of autumn makes place for the ubiquitous grey of winter

The forest, dominated by beech and oak, is situated in an ancient mining region right on the French border. The fog cover does not only conceal the views but dims the sounds. No wind, no rustling leaves or birds to be heard. We quickly retrieve the corner stakes that mark the perimeter of the stand and get to work. The first step now is to number and georeference each individual tree with a diameter over seven centimeters. A quick estimate teaches us that we can expect 50-60 trees per quadrant. My companion cleans the bark with a steel brush and a drawknife before painting on the tree number. The rain that has been falling all night makes the bark wet and the writing difficult. I measure the distance and azimuth to the center of the quadrant. Then I write down the collected information and the tree species. When the transponder does not catch the signal of the Vertex, my colleague has to walk there to point it in the right direction. Luckily it stopped raining, as raindrops can also interfere with the ultrasonic waves of the device. We swap tasks each quadrant; writing on bark with a paint tube is tough on the wrists. By the end of this exercise we reach a total of 208 trees. Not a bad guesstimate! Time to call it a day.

The next morning we proceed with the following stage. First up is determining the diameter at breast height with a measuring tape. This task involves a lot of literal tree hugging. Unless the trunk is too stout, in which case we have to walk around the tree. Before starting the height measurement, it is lunch time. This day the weather gods are really not on our side. The cold and rain force us to eat our bread and cheese lunch in the relative comfort of our cars. Today no extensive tasting of homemade jams, sharing Belgian chocolate or finishing with a warm cup of freshly brewed coffee. Luckily the rain subsides in the afternoon and we can start the height measurement. One person attaches the transponder to the tree while the other one looks for a spot that allows a clear aim at the top of the tree with the Vertex. We manage to measure all trees just before darkness sets in. Black windy roads lead us back through the woods to the warmth of our rooms.

The foggy forest

The following day, we are joined by the local forester. For the assessment of the wood qualities, we always try to get an insight in the local practices and the local wood market. For instance, we learn that in this region, there is a demand for staves to produce wine barrels. That means that good quality oak lengths of one meter can already be sold separately. During the assessment we pay attention to defaults that may count as tree microhabitats, such as fungi, witches brooms or hollow branches. Amusedly the forester remarks that he hasn’t looked at trees this way since he finished school. After lunch, mist sets in again, hindering the use of binoculars to spot hidden microhabitats in the tree crowns. But we manage. And believe it or not, as we successfully conclude the inventory and start heading home, the first rays of sunshine in over a week manage to pierce through the mist and ultimately light up the whole landscape. A subtle nudge of nature to get ready for the next marteloscope?

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