I’ve said so many times that our readers are truly a gift and year after year (18 and counting!) have remained a key part of our editorial process here at TPM. Here is really a special case. You may have noticed that President Trump made this bizarre and almost certainly false comment that the President of Finland told him the Finns avoid forest fires by aggressive raking.

It so happens TPM Reader JI (pictured here at a mushroom exhibition) is an avid TPM Reader from Finland who is also a Phd plant biologist. He did us the service of giving a detailed explanation of how forest fires work in Finland and how raking is just not part of the equation.

My short non-biologist summary would be this: it’s fairly wet and cold in Finland so it’s pretty different. They don’t use rakes to avoid forest fires. Their big problem is bog fires. Many of the best parts of JI’s letter are cris de coeur, insisting on the non-role of rakes in any part of Finnish forage management.

On behalf of all TPM Readers, thank you to TPM Reader JI and we’re sorry about the Trump thing. Email below …

Thanks for covering the case of Mr. Trump’s statement of Finland and “raking”. President Niinistö’s “not remembering” seems to be just a diplomatic way to say “did not say that”!

For what it’s worth, in case this would be useful as a technical background for your work, I am as sending you some biological views to show the falsity of Mr. Trump’s statement. I am not searching number data now, just general views.

– In general, this seems just to be one of Trump’s routine/compulsory smoke bombs, lies and distractions.

– Forest fires in Finland are much limited by the snowy winter (length varies acc. to year and region, but traditionally around 3 months, is shortening due to climate change). Snow and ice are solid water, forests cannot burn in wintertime.

– Even after the visible snow melts, the soil remains frozen for a couple of weeks more, postponing the soil/humus fire a bit more.

– When all the snow and frost have melted, the melting water is still absorbed by the soil/humus for various amount of weeks, giving an important boost for spring vegetation and hampering soil burns.

– Some spring weeks after melting, if dry winds prevail, are vulnerable for grass etc. burns, due to the withered grass, but these seldom develop into economically important. E.g. March-April. After this period, the green leaves make burning more difficult.

(- In whole Finland, making an open fire prohibited in given areas of drought.)

– The most vulnerable period for forest fires is late summer (e.g. July-August), in summers of long-term droughts and winds. Towards September, the rainy fall season usually makes it more unlikely.

– In Finland, the annual rainfall is relatively high (moist winds from southwest prevail), and, very importantly, the Nordic cool temperatures leads to less evaporation, so the soils keep the moisture longer, and also the relative humidity is physically higher in cool temperature. So, our air is often relatively moist (not as moist as in the Atlantic coasts of Norway, however). This seen e.g. in the nearly ubiquitous moss

cover of our forests.

– The soil and vegetation type of Finland, typical for the Boreal vegetation zone, is different than that in Temperate regions. The soil and vegetation would make any extensive raking HIGHLY unpractical and useless, up to directly damaging, in our large forests.

– Due to the climatic conditions, in most forests there is NOT just a mineral soil or a mull where the plants grow. This would be a very mechanistic view. Instead, on the (often “podzole”-type of) mineral soil here, there is typically a felt-like layer of old, brown, still partly un-decayed, fibrous humus layer, consisting e.g. of lignin of tree remains, mixed with living and dead plant roots, fungal hyphae and so on. This layer is rather acidic and can be e.g. from 5 to 15 cm thick and is very important for the forest. If it gets deeply dry in dry summers, it will easily burn, but IT CANNOT BE REMOVED BY RAKING, without damaging the forest’s root and mycorrhizal network. The forest trees absorb their water and nutrients largely in this layer, with the help of the symbiotic fungi, and the mentioned humus layer acts as a moisture buffer for the trees.

– In our many water-logged areas this poorly decayed humus layer extends up to ten meters down, as the turf of bogs, also acting as an important reservoir of greenhouse gases. Difficult to rake so deep….

And bog fires are notoriously difficult to extinguish in long dry periods. – Our forest vegetation under trees consists commonly of berry-bearing and other boreal shrublets such as the blueberry (Vaccinium myrtillus) and lingonberry (Vaccinium vitis-idaea), and under them the acidic humus layer is typically covered by mosses such as Hylocomium splendens, Pleurozium schreberi and several Dicranum species. The bushlets (with their rhizomes in the humus layer) would make any extensive humus-removing raking very INEFFECTIFE, and the gentle mosses would be largely detached from the humus, as would many bush-like lichens on rocky sites such as Cladonia stellaris.

– The continuously falling needles and twigs, when they decay, return important nutrients back to the forest trees. Removing them regularly would deprive the trees and other plants from the bulk of long-term nutrients, not to speak of the extremely complex mesh of nutrient chains of thousands of other forest organisms, from fungi and insects to birds and mammals.

– Any small site CAN of course be raked and many people in rural houses or summer cottages DO rake their lawns and sometimes adjacent forest edges in, say, around 5 to maximally about 20 m radius from the house. The basic purpose of this is NOT fire prevention or forest management, but to keep the yard tidy, to keep the lawn mowable, to accumulate some litter to the garden, just out of custom and so on. This is not forest management, this is cleaning a yard. Such places would develop into grassy sites under the trees, not typical forest.

– If some site would be raked, why would that be done? What would be the effect for the large cost? Sometimes in history, e.g. on some nutrient-poor islands, litter may have been raked in small scale locally and brought e.g. to barns under the animals or in the gardens, not in any significant amount any more.

– The economic semi-natural forests are typically managed by thinning (gleansing) some times during the about 80 years’ logging cycle, but this is done by large forestry machines or farmer’s tractors and by machine saws. The time spent by humans in the forest in each step is tried to be minimized even then. NO PART of the routine management cycle includes raking!

– You are not allowed to rake in other people’s forests, even if you for some reason would like it. Typically, a forest owner is a farmer who owns, say, 20 to 100 hectares of forest in addition to fields and often also goes to additional paid work somewhere else. He or his family would have not time to do it. Who would rake the vast forests?

– In Sweden, our neighboring country with largely similar forests, there were this summer 2018 very difficult and long forest fires, simply due to the exceptionally dry summer (added with random sparks or other fire sources). This is equally possible in Finland, as well. And the climate change is making such summers more and more common, even here in the moister north! So, regarding your arid southern areas, my personal view is that you (and globally we all) are simply gradually loosing large, previously viable land areas, largely due to the serious climate change.

Josh, sorry this lengthy letter, hoping that somebody finds something useful detail in it.