ilkkaleinonen.bsky.social
Research Professor
Natural Resources Institute Finland (LUKE)
35 posts
134 followers
17 following
Regular Contributor
Active Commenter
comment in response to
post
More or less steady state carbon stock now.
comment in response to
post
The harvest rate increased until the peak year 2018. After that, the harvests have decreased and the tree carbon sink has increased. So the the increase of emissions during the recent years is really about soils. Yes, the harvest rates are quite high, but the average age of trees still increases.
comment in response to
post
The harvest rate increased until the peak year 2018. After that, the harvests have decreased and the tree carbon sink has increased. So the the increase of emissions during the recent years is really about soils only.
comment in response to
post
This is a good practical example of the fact that biological carbon stocks are only temporary, and therefore their inclusion in the national net zero targets cannot be scientifically justified.
9/9
comment in response to
post
So, there are three permanent trends behind the increased emissions, the direction of which cannot be changed. Therefore, emissions from forests are likely to continue to increase.
8/9
comment in response to
post
Reason 3: Perhaps the most important reason for the increase in emissions, however, is the acceleration of decomposition activity due to rising temperatures. This is especially the case in the soils of drained peatlands, where there are huge amounts of dead organic matter ready to decompose.
7/9
comment in response to
post
So, aging reduces the sink in two ways: through slower growth of living biomass and through reduced litter production. Therefore, the carbon input to the forest carbon storage is now continuously decreasing as trees are not getting any younger.
6/9
comment in response to
post
Reason 2: At the same time as the decomposition of litter accelerated, litter input into the soil also decreased. The crown of aging trees is smaller in relation to the trunk volume, so less litter is produced now.
5/9
comment in response to
post
And eventually, the rate of decomposition was higher than the rate of formation of new litter. The soil became a source of emissions.
4/9
comment in response to
post
The litter accumulated in the soil, which meant that the soil was also a carbon sink for decades.
But litter is not a permanent carbon storage. The more litter accumulates in the soil, the more carbon it releases into the atmosphere when it decomposes.
3/9
comment in response to
post
Reason 1: In Finland, trees have been a carbon sink since the 1970s. The sink was created by forest regeneration and the development of forest management practices.
When the growth of the forest accelerated, the production of litter (e.g. dead leaves, needles, fine roots) also increased.
2/9
comment in response to
post
Jos halutaan verrata pysyviin hiilenpoistoihin tai fossiilisten päästöjen vähentämiseen, niin silloin tuo 1000 vuoden varastointiaika on perusteltu. Eli pysyvä hiilen varastointi metsiin on yli kymmenen kertaa kalliimpaa esim. BECCS:iin verrattuna.
comment in response to
post
The recent analysis by Curran & Curran showed a decreasing trend of land sink since 2008. That figure looks similar.
comment in response to
post
Of course it is not wood harvesting alone but the managed forests as a whole that generate CDR.
comment in response to
post
If the production keeps removing carbon from the atmosphere, then yes. That is the idea of CDR. But of course there are limits for that. In land-based systems, excess production can turn the negative emissions into positive.
comment in response to
post
Negative emissions indicate antropogenic carbon removals, and yes, they have a cooling effect. That is why removals are generated as part of climate actions (carbon farming etc.).
comment in response to
post
As the framework considers anthropogenic emissions and removals, the reference is unmanaged land, i.e. natural vegetation. All carbon losses following land transformation are accounted for and allocated to products. The framework can be applied for example in product environmental footprinting.
comment in response to
post
Hakkuutähteet tuottavat aluksi nielun maaperään ja muuttuvat sitten päästölähteeksi. Ruotsin osalta tilanne on mielenkiintoinen. Jos nielu johtuu viime vuosina syntyneistä hakkuutähteistä, niin tulevina vuosina on sitten merkittäviä päästöjä odotettavissa.
comment in response to
post
Tuossa puhutaan maaperän nielusta joka on kasvanut lisääntyneiden hakkuutähteiden vuoksi. Sen sijaan elävän puuston nielu on pienentynyt. Se on enää 3 Mt CO2 (Suomessa 13 Mt CO2).
comment in response to
post
But that question should be asked at the national level, it does not concern forestry only. Is it correct to take a credit of decisions that were (accidentally) made in the 50s and 60s and use those credits to offset present day fossil emissions?
comment in response to
post
Yes, not sure about Norway. In Finland the whole carbon sink was mainly created by forestry. Massive forest areas were regenerated during 1950s and 60s, and tree growth was improved e.g. through breeding.
comment in response to
post
The fact that the carbon sink is not as strong as it used to be does not remove the credit of carbon removals that have occurred during the past decades.