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Species-rich forests store twice as much carbon as monocultures
In 2009, BEF-China began as a unique forest biodiversity experiment in collaboration between institutions in China, Germany and Switzerland. The large-scale project investigated the importance of tree species richness for the good functioning of forest ecosystems. Stands of trees comprising different numbers of species were planted -- from monocultures to highly species-rich plots with 16 different tree species on an area of 670 square meter.
After eight years, such species-rich forest plots stored an average of 32 tons of carbon per hectare in aboveground biomass. By contrast, monocultures averaged only 12 tons of carbon per hectare -- less than half as much. During photosynthesis, the plants absorb carbon dioxide from the atmosphere and convert the carbon to biomass. When a forest stores more carbon, this helps reduce greenhouse gases and at the same time also indicates high forest productivity.
The fact that biodiversity increases productivity had previously been demonstrated through experiments in grassland ecosystems in Europe and the USA. By contrast, since it was assumed that all tree species occupy similar ecological niches, a minimal effect of biodiversity was conjectured for forests. Evidently, however, this assumption was wrong. "In the forest biodiversity experiment, biomass increased just as quickly with species richness as it did in the meadow ecosystems. As a result, even after just four years, there were clear differences between the monocultures and the species-rich forests," explains Prof. Helge Bruelheide of the Martin Luther University Halle-Wittenberg, co-director of the German Centre for Integrative Biodiversity Research (iDiv), which together with the Institute of Botany of the Chinese Adacemy of Sciences oversaw the field experiments. These differences grew continuously over further four years.
Impacts of species richness on productivity in a large-scale subtropical forest experiment. Science, 2018; 362 (6410): 80 DOI: 10.1126/science.aat6405
(Score: 2) by Hartree on Monday October 08 2018, @06:47PM (1 child)
So, they are saying old growth forests store less carbon than new?
Reason, old growth tends to reach a low species diversity as the competition battles are fought out. example: Redwood forests. Nearly everything is a redwood tree. They shade everything else out. That's why spotted owls in them need such a large territory. There's not much else than the old growth trees there and owls don't eat redwoods. The animals they feed on are pretty low density.
Given that redwood forests tend to have a lot of biomass, it's just all redwoods, and they live a very long time. I'm not ready to just accept this whole hog without some other ifs ands and whereases.
(Score: 2) by dry on Tuesday October 09 2018, @04:06AM
Aren't Redwoods slow to rot? Around here, some of the old growth forests are mostly Western Red Cedar (Arborvitae) and the trunks can take centuries to rot and return the carbon to the ecosystem. Similar with Douglas Fir, though they rot faster then Cedar, compared to Western Hemlock, they're pretty slow, lots of century old logs laying around.
The growth rate might be slower, but the carbon stays locked up longer, especially compared to man made plantains (usually mono-culture) where the fast growing trees rot really quick