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Comment by bradford | Hacker News Reader

It's a great site, but I don't think many of the listings could be properly categorized as old-growth. For example, I checked out a few samples:

"The oldest trees are estimated to be over 200 years old." https://www.oldgrowthforest.net/md-schoolhouse-woods

"The age of the oldest trees is not certain, but 100 rings have been counted on a downed loblolly pine and a downed chestnut oak. There is no old-growth forest in this park, however, the strong protections put in place on this forest ensure that it may recover in time." https://www.oldgrowthforest.net/va-james-river-park-system

(The exact definition of old-growth isn't agreed on, but I've seen some foresty documents in the PNW that demand tree age of 400+ years as a prerequisite for the old-growth categorization)

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I had always thought of an old-growth forest as less defined by the age of the trees, and more by the lack of human management/disturbance. I think of old growth as being in comparison to a second-growth forest, which had been logged and replanted. I'm not a forestry scientist, just cobbling definitions together as I go. But it seems unfair to say you could never have an old growth forest of aspen—a species where individual trees only live about 100 years—if the forest itself had been untouched since the dawn of time.

It's not about the age of the individual trees but the overall forest since it was last disturbed by humans (on a large scale like logging or agriculture).

Age matters because there are several "thresholds" during which the diversity of species significantly increases and that starts with the older trees falling and decomposing. The conifers in the PNW take anywhere from 50-150 years to decompose before they start breaking apart and littering the forest floor. Once the first generation of trees is broken up and spread around by the wildlife and the fungi species are fully established, the growth of third/fourth/fifth generation of trees and plants become a lot more vigorous. When the second and third generation of trees start falling, they end up creating the dense habitats that supports large food webs from the rodents on up. All the while, the tree roots pull nutrients from deeper and deeper in the earth, allowing the rain and cold to build up a layer of peat on the forest floor that cycles and stores the nutrients, improving the quality of the dirt.

It just takes a while for all these processes to build up.

The east and southeast don't have many ultra-long-lived tree species, outside of cypresses [0].

I think most oaks top out ~100 years and pines ~200. Not as much slow-growth, live-forever stuff.

[0] https://en.m.wikipedia.org/wiki/Taxodium_distichum

Oaks easily go to 500y, sometimes up to 1000!

https://en.m.wikipedia.org/wiki/Oak

I suppose they are the exception tho since 500 year old oaks are likely to be famous. Airlie Oak in Wilmington NC is one I know of.

https://www.starnewsonline.com/story/news/2009/06/13/airlie-...

Right! I guess they are exceptions because we cut them before eldery, not because biological reasons. Cows older than 4yo are an exception because we slaughter most of them before but they could live 5 times more.

Is that true?

I thought super-long-lived trees tended to have special biological optimizations to persist over centuries.

E.g. https://www.nps.gov/parkhistory/online_books/shirley/sec6.ht...

> Cows older than 4yo are an exception because we slaughter most of them before

Huh? A heifer generally won't have her first calf before two years of age. If you are only getting two productive years out of your typical cow, you're doing something horribly wrong.

Right, it's more 4/5 years

Calf 3-5 months Heifer 8-10 months milk cow 4-5 years Bull 18-20 months

https://www.swissveg.ch/life-expectancy?language=en

Looks close to US ranch:

> Meat or beef cows live for 1.5-2 years in the commercial beef industry. However, the natural life of beef cattle is between 15-20 years. Heifers and cows (female cattle) often live for between 5-6 years as they breed to produce the next generation of beef cattle.

https://ohthatschelsey.com/how-long-does-a-cow-live/#:~:text....

Todays milk caws are bred for producing a LOT of milk (30/60L/day), in comparaison those not bred for that produce 4L/day. However this quantity does not keep vealing after vealing and they became unprofitable soon.

Beef cows live for 1.5-2 years, while simultaneously also living for 5-6 years? The claims keep getting stranger and stranger.

I think you misread. Beef caws (male) usually live 1.5-2 years, while milk caw (female) live 5-6 years.

> If you are only getting two productive years out of your typical cow, you're doing something horribly wrong.

What do you mean by wrong ? These are the figures of modern practice.

> think you misread. Beef caws (male) usually live 1.5-2 years

I'll assume I misread "caw". But this apparent multi-sexed beef cattle beast you now speak of is even stranger still.

> What do you mean by wrong ? These are the figures of modern practice.

Under modern practices, the productive lifespan of a cow is usually around 4-5 years, as echoed by your links[1]. If you're only getting two out of your typical cow, something is afoot with the management of your herd. If you are culling them before their productivity has been exhausted, how are you squaring the resources you put into their unproductive early years? In other words, how the hell is your farm managing to stay profitable if you find a cow older than four to be abnormal?

[1] Which was strange in its own right. Can you not speak to the subject yourself?

> is even stranger still.

Thanks to point that out, my English isn’t perfect and a quick search show me that a caw is a female :-)

> speak to the subject yourself

I wasn't explicit enough here neither: "we slaughter [...]" -> "Humans slaughter [...]". I'm not farmer, just some random guy.

For the profitability part : "The value of cull cows at slaughter represents a source of income for dairy farms."[1]

However the profitability incentives varies depending on the breed and lead to ...strange... practices: the male newborn are hardly profitable if from a diary-super-optimized breed and some farms culled them at birth [2]. It's now forbidden in UK but still a practice in Switzerland (yummy Toblerone).

[1] https://www.sciencedirect.com/science/article/pii/S002203021...

[2] https://www.theguardian.com/environment/2018/mar/26/dairy-di...

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