I am concerned by the label "primary forests" - I assume it means climax forest, especially "old growth" containing trees at least half as old as their lifespans. Often, the implication is that this kind of forest has not been subjected to significant disturbance by human activities, such as logging, and that the species composition has not been affected by humans either. Old growth forests have some of the most commercially valuable timber, but occupied land that could be used for second-growth stands that grew more quickly and could be harvested more frequently. For example, in British Columbia, Canada, harvesting in the coastal region is moving to such second-growth stands.
There was a scientific symposium in Canada in 2001 that found difficulty in developing a rigorous scientific definition. I believe the results are available in the FAO data base: at the following: http://www.fao.org/3/xii/0042-b1.htm They concluded: "...Concerns over old-growth conservation go well beyond the more traditional areas of watershed (including water quality) and habitat protection, and includes emerging issues such as the conservation of genetic resources and carbon sequestration. Conservation of old growth is very much a cross-sectoral issue with many interdisciplinary linkages. It is important to dispel the notion that concerns about the disappearance of old-growth forests from our landscape are simply the preoccupation of environmentalists. It is an important issue with implications for ecological science, the long-term health of our forest economy, and our quality-of-life. It is time for the wider forestry community - the forest sector as a whole - to embrace this issue in a more serious way and to take up the cause of old-growth conservation."
My own research, while I was a principal scientist at the International Crop Research Institute for the Semi-Arid Tropics, was partly focussed on the issue of forest uses. I found that, in almost every case, both patches of climax forest, and the mosaic of secondary growth, were generally constituted the ecological "commons" of each community we studied in the Sahel. These appeared to be critical, moreover, in the maintenance of water tables, and in preventing both rainy season flooding and erosion and in preventing dry season failure of wells and other sources of water. As population increased, and, more significantly, as acreage devoted to commercial crops increased, the percentage of land returned to the commons, after a period of cultivation, was falling during the 1980s, and has fallen subsequently. My colleague, agronomist Willem Stoop, and I wrote on this here: https://www.sciencedirect.com/science/article/pii/016788099090214X
In the long run, it became clear that both nomadic pastoralism and slash and burn (long fallow) farming economies tended to produce mosaics of ecological diversity - in forested zones, this resulted in a complex of about 20-25% cleared land growing crops and 80% land in secondary growth. This secondary growth represented various stages from pioneering annual grasses and "weedy" plants, through early pioneering shrubs and trees, through to early stages marking the re-establishment of some of the climax tree species that would eventually become old growth primary forests if left alone. Sacred groves of such ancient trees were found in all the village territories. I suspect that these are essential to the overall process of restoring soil nutrients, for it was in symbiosis between these species and various underground fungi that nutrient capture was completed.
Elinor Ostrom found that the preservation of these areas of forested commons was an essential aspect of long term sustainability even where more intensive agriculture had developed, and emphasized the importance of local management - and control - over the degree of harvesting of trees and other forest products. See http://www.onthecommons.org/magazine/elinor-ostroms-8-principles-managing-commmons and https://www.youtube.com/watch?v=LqC7xG8fxHw
I hope this little contribution of mine is not too late to be of use.
sincerely, Helga Vieirch
Dr. Helga Vierich-Drever