BOTH RSPB and Sussex Wildlife Trust manage the priceless heritage known as Amberley Wildbrooks on our behalf.
There is a lot of maintenance, what with ditching, fencing, grazing, track clearance, etc.
The job is endless, but must be addressed.
No wonder the SWT has recently launched an online appeal for funds.
It also relies a lot on volunteer help in trying to keep this piece of biosphere solvent for all of us to enjoy and preserve for our descendants.
Just to give you something of a clue as to what it is preserving: more than half of all the aquatic plants found in Britain grow in Amberley Wildbrooks.
Years ago, the famous botanist and writer of childrens’ stories: Alison Ross took me out into the middle of the swamp and showed me one of the greatest of all Sussex botanical treasures, true fox sedge, Carex vulpina.
The flower looks like a miniature fox, being red-brown and bushy-tailed as it stands by the waterside half-a-mile in front of the castle.
It grows only here and on the Ouse above Newhaven in the county.
It is also found locally in Yorkshire.
Greater water-parsnip, frogbit and bladderwort are also local treasures, the latter having no ground roots to support its lovely little yellow flower on the end of a spindly procumbent stem.
It has to catch and digest insects for food.
What a curiosity that is.
I think there are close on 400 species of flowering plants in the meadow flood plains.
As you travel through them on the London train, you can sometimes see the flashes of water, and again, a vast inland lake in winter.
Hard rush grows nowadays across these meadows, where 40 years ago I remember these dark green tufts looking like besoms were rare.
The whole place makes an ideal rural landscape, and looks almost 17th-century in its primitive beauty.
This is the place where wild swans come from Russia to spend their winter, and wild ducks cross the winter moon as they sport in flights of many hundreds, the wigeon whistling wild cries of glee high up against the ice-white peaks of clouds.
In summer, migrants come from Africa to breed.
I have heard cuckoos and turtle doves, sedge warblers and reed warblers, peewits and redshanks.
Sometimes there is talk of the rarest duck of all breeding here – the garganey, which has come from Africa too.
Is all this worth protection?
Of course, and for the centuries ahead, for the people who will treasure it as we do today.