Just checked it. Are you sure? This is what our friend found:
This statement contains several inaccuracies about the carbon flow between birch and fir trees.
## Actual Carbon Flow Pattern
The carbon transfer between paper birch and Douglas fir occurs bidirectionally, but the pattern is different from what was stated[3][7]:
- In summer, when Douglas fir becomes more shaded, birch trees with excess carbon send more carbon to the fir trees[3].
- In fall, when birch trees lose their leaves, Douglas fir continues photosynthesizing and transfers carbon back to the birch[3].
## Key Corrections
**Direction of Spring Flow**
The claim that leafless birch receives carbon from fir in spring is incorrect. The research doesn't show this pattern.
**Magnitude of Transfer**
Studies have shown that the net carbon transfer results in a 2-3% gain by Douglas fir from paper birch[5]. This transfer occurs through underground mycorrhizal fungal networks that connect the root systems of both species[6].
**Mechanism**
The transfer isn't simply a "downhill flow from abundance to scarcity." Instead, it's a complex exchange facilitated by mycorrhizal fungi, where both species benefit from the symbiotic relationship[6]. The fungi receive carbohydrates and vitamins from the trees while increasing the trees' ability to absorb water and essential elements, especially phosphorous[6].
The carbon exchange between these species represents a sophisticated ecological relationship that helps maintain forest health and resilience, rather than a simple one-way flow based on scarcity[3].
Sources
[1] Asymmetric belowground carbon transfer in a diverse tree community https://pmc.ncbi.nlm.nih.gov/articles/PMC9325067/
[2] [PDF] Seasonal Patterns of Photosynthesis in Douglas Fir Seedlings ... https://pdxscholar.library.pdx.edu/cgi/viewcontent.cgi?article=1104&context=esm_fac
[3] Exploring How and Why Trees 'Talk' to Each Other - Yale E360 https://e360.yale.edu/features/exploring_how_and_why_trees_talk_to_each_other
[4] Relationships Between Trees and Fungi in a Time of Climate Change https://kids.frontiersin.org/articles/10.3389/frym.2023.1194085
[5] Pathways for below-ground carbon transfer between paper birch ... https://www.tandfonline.com/doi/abs/10.1080/17550874.2010.502564
[6] Paper Birch & Douglasfir: An Odd Relationship | Arbor Day Foundation https://www.arborday.org/perspectives/paper-birch-douglasfir-odd-relationship
[7] Suzanne Simard's Journey - The Nature Institute https://www.natureinstitute.org/in-context-46/craig-holdrege/susan-simards-journey
[8] Tree diversity increases carbon storage, soil fertility in forests | Folio https://www.ualberta.ca/en/folio/2023/04/tree-diversity-increases-carbon-storage-soil-fertility-in-forests.html
[9] CO2 Elevation and Photoperiods North of Seed Origin ... - Frontiers https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2020.00506/full
[10] Forest carbon - Canada.ca https://natural-resources.canada.ca/climate-change/climate-change-impacts-forests/forest-carbon/13085
[11] Carbon in Canada's boreal forest — A synthesis https://cdnsciencepub.com/doi/10.1139/er-2013-0041
[12] Carbon allocation dynamics in conifers and broadleaved tree ... https://www.sciencedirect.com/science/article/abs/pii/S0378112721003467
[13] If a forest has a variety of tree species, is it better at fighting climate ... https://www.cbc.ca/news/canada/edmonton/if-a-forest-has-a-variety-of-tree-species-is-it-better-at-fighting-climate-change-a-u-of-a-study-says-yes-1.6858279
[14] Forests could tip the carbon scales either way on Canada's path to ... https://climateinstitute.ca/forests-could-tip-the-carbon-scales-either-way-on-canadas-path-to-net-zero/
[15] Seasonal dynamics of stem N2O exchange follow the physiological ... https://www.nature.com/articles/s41467-019-12976-y
[16] Large seasonal fluctuations in whole-tree carbohydrate reserves https://pmc.ncbi.nlm.nih.gov/articles/PMC8577199/
[17] Asymmetric belowground carbon transfer in a diverse tree community https://pmc.ncbi.nlm.nih.gov/articles/PMC9325067/
[18] Seasonal dynamics and punctuated carbon sink reduction suggest ... https://nph.onlinelibrary.wiley.com/doi/10.1111/nph.19883
[19] Carbon balance of forest management and wood production in the ... https://www.frontiersin.org/journals/forests-and-global-change/articles/10.3389/ffgc.2023.1242218/full