A couple questions on collecting in the wild

[crab apple]

I have a great opportunity to wild collect several species for bonsai, I have my eye on quite a few variety's but right now I looking at live oaks, laurel oaks and a type of short needle sand pine that is everywhere around here.
I have done quite a bit of research and am still a little confused on a couple things, one is that there is a lot of mention on saving as much of the root ball as possible especially on the pines but still potting them in a large container with a well draining soil, in my case it would probable be mostly Turface, perlite, some pumice and a little pine bark is what I have locally available. Actually have to order the pumice, anyways do you not clean off the root ball? I see some ppl washing it of to bare root and others I assume put the rootball in with the native soil in with the bonsai type soil all around it, not sure which way to go there.
Also for the oaks it has been recommended to use pumice half and half with potting soil, is this a thing? mix potting soil with hard aggregates used in bonsai-seems like the potting soil would just clog everything up.
I didn't realize how poor draining the potting soil was until I got into Bonsai. I'm surprised that stuff doesn't kill everything it gets near.

 

[Shibui]

Different people use different approaches and still seem to have good results. Ultimately it probably comes down to how they manage care post collection. Some of the differences in approach seem to be based on not fully understanding how trees grow and respond to root pruning. Most trees are just as capable of growing new roots as they are of recovering from pruning branches above ground so in most cases keeping lots of roots is not necessary. As usual it varies from species to species so while some trees can tolerate radical root reduction, others don't do so well.
Field soil is implicated in a lot of problems when used in pots but plants can still survive with careful management of water, etc.
Due to the problems associated with field soil in pots I shake/rake off as much field soil as possible while taking care not to damage roots too much. I do not wash roots. Residual soil provides beneficial fungi, etc that can help and are sometimes vital to the tree.

Standard potting soil is good when used in deeper pots and with appropriate watering regime. The problems start when we try to use it in shallow containers and water aggressively.

 

[rockm]

Depends greatly on the species. Pines generally need a rootball with native soil--which is gradually reduced over the years and replaced with bonsai soil. Deciduous trees (which includes live oaks since they are deciduous, but drop their old leaves in the spring as new growth arrives) can be handled a little or a lot more aggressively--including bareroot and hard pruning of roots. Live oak is tricky and hard to collect. I wouldn't be aggressive with the roots. Leave a little of the collected root mass undisturbed.

It's important to work the outer edges of those root masses loose from their original soil and work bonsai soil into the edges. Simply plunking the root mass into bonsai soil can prevent new roots from growing, as roots are reluctant to cross from one type of soil to another...

A note, original soil remaining on the root mass in a container causes problems as it retains too much water, while surrounding bonsai soil drains quickly. That means watering takes some finesse to keep the interior soil from staying too wet and the outer soil from getting too dry. The "beneficial" stuff in the original soil is an overblown benefit. Original soil is more of a problem than a solution.

 

[Wires_Guy_wires]

Potting soil is terrible for our watering habits. For other potted plants that get watered every week or so, it's great stuff. For seedlings, it's even better than most bonsai soil. But we have to work with it, and not against its natural properties.

Sand pine sounds like bad news. Not because of the pine, but because of the sand part. We have patches of desert-like areas in The Netherlands (inland dunes and all) and the pines that thrive there send out deeeeeep roots. They have yamadori character, grazed by cattle, sheep and deer, beaten by the sun, winds and frosts.. But they are uncollectable. You can dig down a foot or two on a tree that's a foot tall and still find no feeder roots. Just one peg diggin down.
I can say with fair confidence that your best chances of success are trees from a forest floor filled with debris and organic dandruff. Because pines in those soils tend to skip the tap root and form feeders from the base. Circle back around to potting soil; that's a positive trait of potting soil that can help us develop a good root system from the start. Throw a couple seedlings in bonsai soil, and they'll behave as if they're in sand. Throw them in potting soil or coco coir and they'll produce a dense mat of feeder roots all around. If you water right and don't kill them of course.

Collecting successfully is a skill on its own. Don't dive into the deep end too soon, because you'll be killing a couple on your first tries. Leave the best trees for when you're more experienced and know how to handle things. Trust me, you will look back at one point and say: dang, if only I would've known!
I still remember that one tree and it still pisses me off that I wasn't experienced enough to keep it alive.

Native soil can be a blessing and a problem. I had a wonderful pine going into refinement, then it suddenly stopped moving. Turned out that the native soil was staying too dry and the surrounding soil drained too fast. Now it'll take a couple more years to be back at that point. I have other trees that wouldn't have made it without some native soil left in their rootballs.