Pros and cons of tarp-based invasive management?

Hi - I've got some square footage that I want to convert over into a forest garden next year, and currently it's overgrown - mostly with vinca minor, but also with various saplings and quite a bit of nasty poison ivy.

I'd like to deal with it all as quickly and painlessly as possible, without using any herbicides - I will be growing edibles there soon and would rather not go that way.

Can I put tarp down to kill off the vinca + poison ivy? Does it need to be a certain color or thickness to ensure minimal light is getting through? About how long would I want to leave the tarp down?

I'm also thinking about putting down a cardboard and mulch treatment for the soil, though the soil is already in pretty decent shape as it is a mature forest area. If I'm going to go that route, is the tarp even necessary? Would the cardboard and 2-3" of mulch kill off all the unwanted stuff anyway?

Thanks in advance - any information or advice is welcome and helpful!

I think that using a tarp or black plastic is a fantastic idea.  You may need to leave it down for a full two growing seasons to completely smother some plant species.  

Pro:  It smothers all light and causes the plants to die a natural death.
Pro:  You can selectively plant other things in a hole in the plastic and allow the vines to run over the top of the plastic, thus still utilizing that land and obtaining a yield.
Pro:  Ease of application.  It's helpful to have a partner to get on the other end of the long sheet of plastic and help you stretch it into place, and then secure it by throwing bricks down every 3 feet along the border.
Pro:  If you can utilize natural slope and the contour of the land, you can easily direct the rainwater to other locations where you want it.  So not only does the lack of light kill the plants below, but also the lack of moisture.  Meanwhile, the plants you wish to encourage get an exponentially larger amount of "rain fall", as the plastic can be used to channel the water.

Con:  Cost.  Heavy, UV-resistant plastic isn't cheep.  Like any other tool, pay more and buy quality.  
Con:  Wasted land and wasted sunlight.  At least for a short season, that is land that will go unused, or minimally used if you wish to keep the plastic pristine and not punch holes in it.

I used black plastic mulch exactly as you are proposing.  I use it to smother crimson clover cover crop in the spring.  I also use it to channel rain water toward swales.  

Best of luck.

If blocking the light will work and you have access to some, cardboard might be better than tarps for a couple of reasons.

First, it can stay in place. Fungi will eventually colonise it, sequestering and breaking down adhesive and dye components, and if there's any concern about the native fungi handling the job, I would do monthly applications of oyster mushroom slurry. If there were any breakouts, I would just drop another piece/sheet of cardboard.

This is of benefit against poison ivy in two ways.

First, you don't risk being afflicted with poison ivy due to contact with the tarp.

Second, if the cardboard unexpectedly breaks down faster than you'd expected, all that you need do is add another layer, perhaps only over weak spots. If the plastic breaks down, however, you're looking at the possibility of tiny pieces of plastic virtually impossible to track down, all mixed up in your soil and mulch layers. And if you're planting into that plastic, through holes, either you get to cut the plastic out from around the established plants, or you have to chop down the plants, and either way, you are limited in your next use of the plastic mulch, if it can even be used again.

I suggest that, even where multiple layers of cardboard are either unavailable or impractical, tarps are one of the worst materials to use in this application.

I further suggest that, if cardboard is inutile, then some liner material tougher than tarps be used, like pool or pond liner, for instance.

-CK

Better than both cardboard or plastic, or best of all in combination with them, is CARPET!  This can often be dumpstered or had for free whenever and wherever people change out old carpet.  It's heavy, so it won't blow away as easily.  Compared to cardboard or tarp or plastic it's comparatively sun-proof and rot-proof, so you can just place it and forget it for a year or three....and then move it to the next place after you're confident the weeds under there are smothered.  By itself, it will let some rain through, but is largely light proof, so if you want to add dessication to light exclusion for weed control you could put plastic under the carpet.  And don't buy plastic!  Plenty is to be had for the scrounging from your nearest mattress or furniture store dumpster!  Most such items are shipped in huge plastic bags which can be slit open into large rectangular pieces.

I would only use natural fibre carpet. They do degrade over time, meaning that if it's a synthetic, or a synthetic blend, it gradually sheds microplastics into your soil.

I would only use waste plastic in such a manner if I had a proper high-temperature incinerator, maybe even retort-based, that can burn the plastic without creating dioxins. Even then, I would probably use cardboard. The plastic would go right in the incinerator.

-CK

Con: what about critters and seasonal flowers and such that you might have missed.

Pro:  it seems my attempt to reduce brambles with cardboard and mulch only gave it more time to work on its root system.   When they emerged a season later the brambles were pleasantly surprised to find all the wonderful wood chips.  

I would use cardboard and mulch where you can. Perhaps use plastic where you know you need a hard core fix, like a solid poison patch.   Don't feel you need to clean it all up,  open, fertile land will sprout quickly with problem plants you may not currently have.  

Thanks, everyone, for taking the time to reply. Lots of good thoughts and helpful comments here.

I think I've found an even better solution... a friend with a goat! I'm going to bring him over one weekend soon and let him go to town, looking forward to seeing how he can handle things.

For other areas where I've already got a couple things planted, or need a somewhat more delicate touch, I think I'll give the cardboard and mulch strategy a shot.

Thanks again.

If the goats eat it, they will only be eating the top part and the roots will still be there to resprout.  You can cut with a weed wackier down to the soil and be even more thorough than the goats but I have found that vinca, ivy, poison oak, and blackberries all come back from the roots even when eradicated above ground with a weed wacker  or tri-blade, and I own goats

The previous owners here used old carpet to smother weeds and I recommend against it,  I still find yarn from avacado green shag carpet in the soil in spots and suspect that the chickens have eaten some.  I suppose it could be used short term on its way to the dump but is risky and is harder to move again when waterlogged