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submitted 2 days ago by fossilesque@mander.xyz to c/science_memes@mander.xyz

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[-] Track_Shovel@slrpnk.net 26 points 2 days ago

Point of clarification: organic matter doesn't really retain the nutrients but acts as the slowly mineralized pool of nutrients associated with soil quality.

The way you describe it is similar to how a sponge works rather than a storehouse.

You are right, though, in that you don't need to fertilize trees for the most part. Forest soils are hilariously low in nutrients: TOC is around 1% and N is next to non existent (N is highly labile), while P and K are moderate to high. As a result, forests veg is most competitive in nutrient poor conditions. If you fertilize a disturbed area, you get a pile of weeds and grass that can set back your revegetation timeline because your desirable woody spp now have to out-compete them. This process still happens if you don't fertilize, but it's generally less pronounced and allows some woody plants to gain the foothold they need

[-] LibertyLizard@slrpnk.net 2 points 9 hours ago

Well, based on our prior conversations I suspect you know far more about soil science than I do, I only know the basics necessary for arboriculture.

So what you wrote is of course accurate but I understand both to be at play here—leaves break down into humus that chelates minerals and supports fungi that can hold onto nutrients and keep them from leaching away in rain. Leaves also provide a physical barrier that protects soil from physical erosion. But let me know if I got anything wrong.

My overall point was mainly just that you don’t need to replace leaves with fertilizer if you are removing them, but it’s still a good idea to leave them in place for other reasons.

[-] mojofrododojo@lemmy.world 2 points 1 day ago

I read a while ago that trees attempt to reduce competition by dropping their leaves to prevent saplings growing too near. Was that all bunk?

[-] Track_Shovel@slrpnk.net 4 points 1 day ago

Not bunk, but not an evolutionary strategy, I imagine. Leaves are dropped because they are too hard to maintain, rather than the benefit the trees get from mulching out competition.

[-] sem@lemmy.blahaj.zone 1 points 7 hours ago

Depends on the type of tree -- pine trees do benefit from the acidification of soil via their dropped needles - it reduces competition.

[-] JovialMicrobial@lemm.ee 4 points 1 day ago

I'm not directly aware of any trees that do that, but it honestly wouldn't surprise me if that was true for at least one species.

Most trees that drop seeds have methods of getting them away from the parent tree. Maple trees have little helicopter twirlies, oak trees have animals carry them off, some trees grow new ones from their roots called suckers.

I'll try to look it up later because now I'm curious. I'll update here if I find anything interesting about trees dropping leaves to prevent new ones growing too close.

I don't think my arborist textbook said anything about that specifically, but I'll double check there first.

[-] mojofrododojo@lemmy.world 2 points 1 day ago

Thanks!

[-] JovialMicrobial@lemm.ee 2 points 14 hours ago

Np! I couldn't find any evidence that any species of tree use their leaves to prevent new ones from growing too close.

The lack of light, water, and nutrients would kill and new saplings all on its own.

That might be an old hypothesis that later got disproven, but most people don't keep up on forestry sciences so that's understandable!

[-] mojofrododojo@lemmy.world 1 points 3 hours ago

appreciate it.

[-] silasmariner@programming.dev 3 points 1 day ago

Some trees do a bit, I guess? Like, beech trees will release some chemicals to inhibit other plant growth, and iirc their leaves do that as they decompose, as well as the root system itself. But depends on the plant and mostly bunk I believe.