650sqm / 0.15acres of tough weeds by a river - best livestock to clear?

The southernmost point on our property is dominated by nettles, creeping buttercup, docks and a few grasses. Since I've been mowing it with a scythe and removing the cut grass, a few wildflowers are trying to come up, but the weeds mentioned above are fiercely pinning them back. 5/6 trees, willows and alder, but in bad shape, around a shady depression in the ground.

The whole area is obviously not big and fronts a river. I want to clear it of these weeds, spread some wetland meadow seeds, and plant more trees.

To reset I started mowing circa 4 years ago, but it is extremely arduous among all the other mowing to do (overall property about 1 acre), and hand pulling (particularly the nettles) is even more strenuous. There are seemingly more weeds each year. Exploring better ways, most advice is either spraying something nasty (even from rewilding / organic gardeners!) or black plastic for months. These are not only short-term but also massively expensive.

Livestock isn't free but would provide a yield, fertilise, and all the good stuff we already know. But given the limitations of location (by a river) and the small size, what would you pick for the best balance of resetting this space? I think it's either a couple of pigs or goats, but I do not know. I am guessing a window of circa six months from here until the other end of the year before the area's wetness would be a problem. Pigs might, I assume, dig out roots, so sound like the strongest contender to me, but I am not fixed in a view, just in trying to reset this space.

Other considerations? I have a terrier dog (training to be done there), who will need to adjust some, and a public woodland is nearby, so I have to consider smell and noise a little: UK, zone 9.

Goats seem good to me.

Don't underestimate sheep for tidying up rough pasture. Older ewes are best...they'll mow through all sorts of stuff. They don't root like pigs and aren't as troublesome as goats.

Phil Stevens wrote:Don't underestimate sheep for tidying up rough pasture. Older ewes are best...they'll mow through all sorts of stuff. They don't root like pigs and aren't as troublesome as goats.

Thanks. I'll assume that 650sqm is a bit tight for keeping them though?

Not if they're someone else's and you can send them back when they've done the work.

Surprisingly perhaps chickens may be your best answer.  That would not be too small an area to confine a laying flock.  The dock and nettle roots are persistent but my experience is the hens are more persistent in eating them. the buttercup roots are shallow and do not stand up to the scratching.  If the terrier  will be protective rather than harassing then you will only have to invest in net and get pay back in eggs.  
This area used to be covered with the weeds you described.

Goats and sheep cannot tolerate wetlands.  They would quickly die from liver fluke and other parasites in that climate.  

The weeds are growing because calcium is not available, or commercial fertilizer with nitrogen or chicken litter (also high nitrogen) was applied at one point.  Buttercup, in particular is an indication of excess nitrogen fertilizer/calcium deficiency.  Keep mowing it, will weaken the plant enough it eventually will fail to come back.  Applying a little calcium should also help.  

650 sqm isn't that hard to control.
Cut all to the ground then take black foil and cover the entire area for 6 month - summer incl and bake them properly.

After6 month or so seed out an annual ground cover that grows quickly which will most probably outshade any return.