Aim To examine the contribution of large‐diameter trees to biomass, stand structure, and species richness across forest biomes.
Methods We examined the contribution of large trees to forest density, richness and biomass using a global network of 48 large (from 2 to 60 ha) forest plots representing 5,601,473 stems across 9,298 species and 210 plant families. This contribution was assessed using three metrics: the largest 1% of trees ≥ 1 cm diameter at breast height (DBH), all trees ≥ 60 cm DBH, and those rank‐ordered largest trees that cumulatively comprise 50% of forest biomass.
Results Averaged across these 48 forest plots, the largest 1% of trees ≥ 1 cm DBH comprised 50% of aboveground live biomass, with hectare‐scale standard deviation of 26%. Trees ≥ 60 cm DBH comprised 41% of aboveground live tree biomass. The size of the largest trees correlated with total forest biomass (r2 = .62, p < .001). Large‐diameter trees in high biomass forests represented far fewer species relative to overall forest richness (r2 = .45, p < .001). Forests with more diverse large‐diameter tree communities were comprised of smaller trees (r2 = .33, p < .001). Lower large‐diameter richness was associated with large‐diameter trees being individuals of more common species (r2 = .17, p = .002). The concentration of biomass in the largest 1% of trees declined with increasing absolute latitude (r2 = .46, p < .001), as did forest density (r2 = .31, p < .001). Forest structural complexity increased with increasing absolute latitude (r2 = .26, p < .001).
tw0pounds on May 9th, 2018 at 03:24 UTC »
Again, the 1% taking all the biomass from the rest of us
DSJustice on May 9th, 2018 at 00:56 UTC »
The second sentence in this title is quite precisely incorrect. The study states that a preponderance of biomass is in large trees, and recommends preserving them... for other reasons.
Yes, the amount sequestered depends mostly on the abundance of big trees. But the amount that a forest can sequester is in fact inversely correlated. The big trees are at steady state. If sequestration rate is the most desirable feature, then the most sensible thing to do is to cut down the big ones and convert them into forms where their carbon isn't released.
Nobody's arguing in favour of it, but it should be quite clear that a young growing forest sequesters more carbon than a mature, static one.
EDIT: I was writing quickly, not expecting to be at the top. Yes, big trees are still adding wood. What I should have said is that mature forest comes to steady state. The rate of sequestration for an area of big, mature trees is simply not as high as the same land with the adolescent trees that the same plot can support in much larger numbers. The areal sequestration rate is an S-curve with tree age. If I have time in the morning, I'll go digging for a citation.
FeivelSwindlebaum on May 8th, 2018 at 22:19 UTC »
If we're looking at biomass...if we look at density new trees are far more effective carbon scrubbers.