I am sorry if I don’t go deep enough or I have wandered somewhat. I am not a researcher and I don’t have a degree.
What I found (research listed below)
The first three articles support the idea that primary forests have indeed been reduced in area. Although complex, the global area is reducing for old growth forests.
Reforested land or plantations do make up for it somewhat but ultimately the amount of land that is forested has decline over the last 300 odd years. Not a massive surprise.
It does appear that the temperate regions (Russia) remains about the same although it is stressed. Tropical regions are not doing as well (
https://www.sciencealert.com/worlds-tropical-forests-declining)
I then saw something about soil and carbon, so I looked into that to see if there was a difference between how much carbon was held in old growth forests compared to plantation forests. From what I can determine at this quick glance, is old growth forests store a lot of carbon and the soil goes deeper. Reforested or plantations also store a lot of carbon in the soil but the depth of the soil is less and the root systems are not as deep as old growth forests. BUT, plantation forest are a positive influence in taking carbon out of the air and into the soil and is one way to improve soil quality over time. (my thinking is it would be better to simply not destroy old growth forest in the first place)
Burning old growth forests does release more carbon via burning and then soil degradation after the fact, something that is happening in Central Africa, SE Asia and the Amazon. Australia as well, but I don’t think that is deliberate, that is just climate changing in a way that allows more and bigger fires to occur naturally.
This is getting way off track, if I dig any deeper I will find myself down a bottomless pit of reading.
In short, old growth forests are reducing over the last 300 years. Reforestation is sort of keeping up but is losing the battle, and the quality of forest (diversity of life, soil quality etc) is reduced.
I am so sorry for dragging the wildfire thread off topic. The only thing I got from this is that old forest destruction via burning is far worse than other types of forests mostly because of the degradation of soil and reduced diversity of life.
Article One
Abstract
Here, we provide the first global gridded estimates of the underlying land conversions (land‐use transitions), wood harvesting, and resulting secondary lands annually, for the period 1700–2000. Using data‐based historical cases, our results suggest that 42–68% of the land surface was impacted by land‐use activities (crop, pasture, wood harvest) during this period, some multiple times. Secondary land area increased 10–44 × 106 km2; about half of this was forested. Wood harvest and shifting cultivation generated 70–90% of the secondary land by 2000
https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2486.2006.01150.xArticle 2
Abstract
The results of a new approach to the specification of the relationship between deforestation and population are presented. They suggest that approximately half of the deforestation that has occurred over the long sweep of human history can be explained statistically in terms of population growth. It is cautioned, however, that serious conceptual and methodological problems confront the analysis of the relationship.
https://onlinelibrary.wiley.com/doi/abs/10.1002/(SICI)1099-1085(19981030)12:13/14%3C1983::AID-HYP713%3E3.0.CO;2-MArticle three
Forests in Flux
Forests worldwide are in a state of flux, with accelerating losses in some regions and gains in others. Hansen et al. (p. 850) examined global Landsat data at a 30-meter spatial resolution to characterize forest extent, loss, and gain from 2000 to 2012. Globally, 2.3 million square kilometers of forest were lost during the 12-year study period and 0.8 million square kilometers of new forest were gained. The tropics exhibited both the greatest losses and the greatest gains (through regrowth and plantation), with losses outstripping gains.
https://science.sciencemag.org/content/342/6160/850Soil
Article 1
Abstract
Old-growth forests remove carbon dioxide from the atmosphere1,2 at rates that vary with climate and nitrogen deposition3. The sequestered carbon dioxide is stored in live woody tissues and slowly decomposing organic matter in litter and soil4. Old-growth forests therefore serve as a global carbon dioxide sink, but they are not protected by international treaties, because it is generally thought that ageing forests cease to accumulate carbon5,6. Here we report a search of literature and databases for forest carbon-flux estimates. We find that in forests between 15 and 800 years of age, net ecosystem productivity (the net carbon balance of the forest including soils) is usually positive. Our results demonstrate that old-growth forests can continue to accumulate carbon, contrary to the long-standing view that they are carbon neutral. Over 30 per cent of the global forest area is unmanaged primary forest, and this area contains the remaining old-growth forests7. Half of the primary forests (6 × 108 hectares) are located in the boreal and temperate regions of the Northern Hemisphere. On the basis of our analysis, these forests alone sequester about 1.3 ± 0.5 gigatonnes of carbon per year. Thus, our findings suggest that 15 per cent of the global forest area, which is currently not considered when offsetting increasing atmospheric carbon dioxide concentrations, provides at least 10 per cent of the global net ecosystem productivity8. Old-growth forests accumulate carbon for centuries and contain large quantities of it. We expect, however, that much of this carbon, even soil carbon9, will move back to the atmosphere if these forests are disturbed.
https://www.nature.com/articles/nature07276Soil article 2
Results
Mean annual temperature (MAT) was the most important predictor of soil C. Forest age explained little to no variability in soil C, in contrast with above‐ground studies. Data on long‐term trends in soil C are limited, as median time since forest growth was 15 years. Soil C stocks were similar between tropical secondary forests, tree plantations and reference forests. Differences between plantation and successional forests only appeared below 10 cm on sites with MAT < 21.3 °C. Former pastures and cultivated sites differed from each other only to depths of 30 or 100 cm. Climatic variables appeared multiple times across all layers of the regression trees, consistent with strong interactions between MAT and precipitation on soil C stocks.
https://onlinelibrary.wiley.com/doi/full/10.1111/j.1466-8238.2012.00788.x