Cutting Down Forests Releases Green House Gases

Eucalyptus forests are exceptionally good at sequestering carbon: They’re big and fast-growing, with dense wood and long lives. The forests store even more carbon in the soil, much of it in the top three feet. This is true of Sutro Forest, of Mt Davidson, of the forested areas of Sharp Park and McLaren Park and Bayview Hill, the forests on Yerba Buena island. All these forests are threatened, and the people who want to cut them down have understated the expected release of carbon once the trees are cut down, the soil churned up, and the chipped trees left to decay.

The article below is specifically about such understatements in UCSF’s Draft Environmental Impact Report for the Sutro Forest Management Plan (that starts with cutting down 6,000 trees in Phase I). But it’s the same story in all the other forests we mentioned: The carbon impacts are ignored or minimized with bad data.

This article is reprinted with permission from SaveSutro.com, a website that advocates for Sutro Forest.

Sutro Forest is an excellent carbon sink: The eucalyptus trees are tall, fast growing and have dense wood. In some parts of the forest, the mid-story of blackwood acacia boosts this carbon storage as well. The understory is lush and evergreen. The forest floor is damp most of the time. It’s practically the perfect carbon forest. It’s also a special ecosystem and excellent wildlife  habitat.


Disturbing this forest is going to release Green House Gases (GHG), and the Sutro Forest DEIR (where the deadline for comments closed on September 22nd) underestimates how much. Here, we publish with permission the comment from Eric Brooks. He’s the Sustainability Chair, San Francisco Green Party and Campaign Coordinator, Our City SF. [Please note: all the photographs in this article are ours and not part of the comment sent to UCSF.]

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Comments To: Draft Environmental Impact Report (Draft EIR) – UCSF Mount Sutro Open Space Reserve Vegetation Management Plan

Fundamental GHG Calculation Flaws & Neglect of Wildlife Habitat Retention Strategy

To all concerned with the Draft Environmental Impact Report for the UCSF Mount Sutro Open Space Reserve Vegetation Management Plan,

I write to raise very serious concerns about very fundamental and deep flaws in the Draft EIR (DEIR) assessment of greenhouse gas emissions from the proposed project and related wildlife habitat impacts.

The assessment has key and deep flaws in its methodology for greenhouse gas assessment, and must be fundamentally changed, and the assessment completely redone.

1) The first deep flaw in the methodology and assessment is the assumption on page 4.7-3 that:

“Forest‐soil carbon is a large, stable pool, accounting for some 50 percent of the total forest carbon and changing very slowly over hundreds of years (Kimmins 1997). For timeframes of 100 years and less, forest accounting can ignore this pool and focus on changes to more labile forest carbon components (i.e., trees, understory, litter).”

This assumption is simply not correct and completely ignores the fact that when forest soils become both disturbed and more exposed to the elements, due to tree and vegetation removal, vast amounts of carbon in the form of CO2 and methane are released *from* the soil. The greenhouse gas emissions calculations and assessment must therefore be completely redone to include soil carbon losses in the calculations.

2) The second deep fundamental flaw in the DEIR greenhouse gas assessment is its reliance on the Significance Criteria under section 4.7.5 on page 4.7-10

This criteria is solely an arbitrary emissions cap and is the wrong criteria. The only proper criteria by which to assess greenhouse gas emissions of a forest is to compare its net carbon sequestration and emissions before disturbance, to its net sequestration and emissions after disturbance, in order to make a comprehensive assessment of its full internal net sequestration and emissions impacts – including all soil impacts and carbon losses and sequestration. It is the percentage net increase of greenhouse gas emissions in any given forest that matter, not an arbitrary cap on a specific emissions number which is not related to the full carbon cycle of that specific forest.

Therefore this assessment must be fully redone to examine solely the correct net sequestration and emissions, from the forest area that will be managed, accounting for all factors, and also accounting for the fact that near term net emissions over the next 20 years are the most significant because it is over the next 20 years that the planet is hitting a wide array of extremely dangerous climate crisis tipping points, and also because that is the proper window in which to analyze the forcing effect of methane (about 87 times higher than CO2 under that time frame).

3) Besides, and partly because of, the completely incorrect omission of soil carbon loss in the assessment, the net sequestration/emissions calculations in section 4.7 are far too optimistic and appear to be incorrect. This section does not properly and fully account for all emissions and sequestration losses, with an eye to new data which shows that after forests are disturbed it takes at least a century, and likely longer, for a disturbed forest to return to net sequestration of carbon. See links below which discuss these dynamics and which can serve as a starting point for redesigning and redoing your greenhouse gas analysis to make it an accurate one.

4) Chipping of felled and downed trees induces them to lose their carbon to the atmosphere much more rapidly. This assessment must be redone to show options for not chipping felled and downed trees at all, and instead leaving these trees intact, and on site, both as snags and downed trees. (See point 5.)

Chipping in Sutro Forest – 2016

5) Removing any vegetation (especially trees, including dead and felled trees) from a forest, drastically reduces the ecological capacity of that forest to uptake, store and retain carbon, and also dramatically reduces the crucial role of intact dead and dying trees to serve as wildlife habitat.

This DEIR contains no management assessment or mitigation plans that would call for a dramatic reduction in tree felling and removals in order to leave the forest and its soils as undisturbed as possible in order to maximize carbon sequestration, and maximize wildlife density and biodiversity through enhanced intact habitat. See the third link below to the report “The Myth of Catastrophic Wildfire” by expert forest ecologist Chad Hanson, PhD, to get a sense of, and some numbers on, the importance of leaving dead and dying trees intact and on site in a forest.

This assessment must be completely redone to show a management and mitigation option which *only* removes dead and dying trees *which pose a direct threat to human health and safety and property integrity* while leaving all other trees in the forest undisturbed. This assessment must include both net greenhouse gas, and wildlife density and diversity impacts.

References:

Old-growth forests as global carbon sinks – Sebastiaan Luyssaert, et al
(contains extensive data showing that forests store more carbon the less they are disturbed)
https://www.researchgate.net/publication/42089659_Old-growth_forests_as_global_carbon_sinks_Nature

Forest Carbon Basics – Mark E. Harmon, PhD (contains basic numbers for how forest and soil carbon dynamics operate over both short and long term timescales, and shows clearly that disturbed forests store less carbon for a century or longer)
http://our-city.org/Forest_Carbon_Basics-Harmon.pdf

The Myth of Catastrophic Wildfire – Chad Hansen, PhD
(See pages 19, 22 and 23 *and* referenced documents and studies)
http://johnmuirproject.org/wp-content/uploads/2014/12/TheMythOfTheCatastrophicWildfireReport.pdf

Thanks for your attention to this extremely important matter.

Eric Brooks
Sustainability Chair, San Francisco Green Party
Campaign Coordinator, Our City SF

Sutro Forest

Sutro Forest viewed from Forest Knolls

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