post by dave bangs, Author of "A Freedom to Roam, Guide to the Brighton Downs"
Chalk grassland functions at a landscape scale. It is only sustainable at that scale.
Many of its special species and groups of species depend upon a very large footprint of open grassland to move across in response to climate and management fluctuations, competition & other exigencies.
At the top of the scale of size we see its mega fauna (Great Bustards et al) only able to survive at the scale of Salisbury Plain...but Musk & Frog Orchids, the heathers of the chalk heath sub-system, Wartbiters and other small beasties, herbs and lower plants need large variable open matrices for their life cycles and long-term survival.
Chalk grassland can't survive as small fragments
The 180 shattered fragments of its ancient mantle on the Brighton Downs are intrinsically vulnerable to species loss and attrition from woody vegetation, farm sprays, dereliction and breeding failure.
On one tiny-but-rich fragment I have watched Adonis and Chalkhill Blue, Heath and Carthusian Snails disappear in recent years
Small sites are difficult to graze and manage. Even at the Castle Hill complex there are / were a number of small 'island' sub-sites that are losing cover and biodiversity through dereliction.
Chalk grassland's survival chances are reduced by the proximity of wood and extensive scrub.
It is not for nothing that Salisbury Plain's huge species-rich grasslands have survived more or less intact for 200 years since the Napoleonic plough-ups were reversed. Its large-scale treelessness meant that there were no sources from which woodland could invade.
It is a stable ecosystem.
By contrast, the West Sussex Downs' historical mixture of BIG woods and BIG sheep pastures in close proximity meant that when the economy of large-scale livestock pasturage collapsed the woods invaded all over. Chalk grassland is almost extinct except for fragments at Kingley Vale, Harting Down, et al - and woodland has invaded their footprint on a massive scale.
Whitehawk Hill's patchwork of scrub and grassland meant that it took a mere 15 years of under-management for scrub to invade about 60% of the chalk grassland we had restored or which survived. ..
Grazing ISN'T sufficient for chalk grassland management
There has been much talk of "natural processes" - i.e. hands-off free range grazing alone - conserving chalk grassland in a sustainable way.
It is not true.
Scrub MUST be kept under control by human management...which took place in the past for livestock winter litter and forage, for thatch, firing (e.g. bakers' ovens) and small scale construction (tools, hurdles, dead hedges et al) for local domestic and wider economies.
We have to ROLL-BACK invasive scrub in many places - often drastically - if shrinking chalk grassland sites are to survive in the long term.
Scrub is good and scrub is bad
Scrub is part of the chalk grassland ecosystem - but a minority part. A whole suite of species like Stonechat, Linnet, the Whitethroats, Yellowhammer and many mini-beasts need scrub for cover, breeding, hibernation, and forage...whilst depending on the larger matrix of grassland as well.
Scrub can also form huge single-species thickets that are very poor for wildlife except common mosses and small numbers of co-dependant species.
Ring Ouzel's on migration like bushes & little thickets on bare hillsides. They remind them of their homes on fell and peak. They won't hang about in wooded countryside.
Multiple public values
the restoration of the chalk grassland mantle is...
...good for nature...good for soil retention...good for food and clothes production...good for our recreation and delight...good for protecting the marks left by the ancient peoples...good for the eye to gaze upon "bare slopes where chasing shadows skim...clean of officious fence or hedge...half wild or wholly tame"
Chalk grassland LOVES being trampled. It LOVES being eaten. It LOVES being sat on. It LOVES sheep and cow shit.
That makes it pretty special!!!