Dr Bob Gibbons is a freelance botanist, photographer, lecturer, author and owner of Natural History Travel. He is a Trustee of The Grasslands Trust and member of its Conservation Committee. He sent us these thoughts from the Greek island of Chios.
In lowland Britain, after millenia of farming, we have become accustomed to a clearly demarcated countryside, where most units end in a straight line such as a fence, hedge or road. There are many lovely areas of woodland, heathland and even grassland, to be sure, but in most cases these habitats, even if they are nature reserves, end in an artificial boundary where there is an ownership or management change. This might not sound like an enormous problem, but in a number of ways, it is.
Looking first at the simple structural issues, there are several effects. Take, for example, an ancient woodland adjoining a flowery old pasture, both excellent habitats in their own right. The wood provides shelter for the grassland, but because of the normal grid pattern of much of the countryside, this will almost certainly affect only one wind direction. When the wind blows from any other direction – and this may often include the prevailing wind – the grassland is unsheltered. This affects humidity, warmth, and the movement of species, and will strongly affect both the feeding and reproductive behaviour of much animal life, especially insects. Butterflies that are towards the northern edge of their range in Britain, for example, are unable to colonise exposed sites, even if they are otherwise suitable. Under more natural conditions, woodlands and grasslands intergrade, often through intermediate scrub stages, creating an endless spectrum of micro-habitats with varying degrees of shade, shelter, humidity, fertility and other features. A much wider range of both plants and animals will thrive under these circumstances. Secondly, a woodland edge that abuts a fence or other solid boundary will almost certainly present a uniform front of trees, without major gaps. Such uncompromising edges do little to invite interchange between habitats.
Apart from these structural issues, there is, in any case, a strong need for more combinations of prime habitats in our over-used countryside. Two or more good habitats have a synergistic effect, the whole becoming more than the sum of their parts. So many species need something from each habitat and will fail, or fail to thrive, if only one element is present. Green woodpeckers, for example, need woodland – or at least well-treed – areas for breeding, but feed mainly in old pasture. Smooth snakes, and other reptiles, need the open warmth of heathland for breeding, but need to retreat to damper or shadier areas in the event of extreme heat or fire. Many plants, such as Primroses, Columbine, or the uncommon but lovely (despite its name!) Bastard Balm do far better in the semi-shade and increased humidity of a woodland edge.
But it’s insects that are most affected. The steady decline in abundance and diversity of our native insect fauna is well-known, and there are many causes, including general habitat loss, pesticide use, fragmentation and others. The lack of good habitat mosaics and interfaces is almost certainly another one. So many insect species need, for example, woodland conditions for successful breeding, and open flowery grassland for feeding – fritillary butterflies, hairstreaks, longhorn beetles, many moths and a host of other ‘macro’ insects, leaving aside the smaller insects of which we still know too little all thrive under these conditions. And in this fast-changing world of global warming, such micro-variety of habitat provides a much better cushion against severe conditions of drought or excess rainfall than do simple straight-line boundaries.
If you visit a number of other European countries, that may frequently have a much poorer record of, and interest in, nature conservation than ourselves – such as Greece, Bulgaria, France or Romania – you soon realise that their countryside is much more alive with the scents and sounds of nature than ours is. Climate plays a part, of course, but one strong linking factor in the best areas is the intergrading and overlapping of large areas of habitat, especially of grassland, woodland and scrub. The bigger and more varied they are, the better.
So what should we do about it? We need more larger mosaic reserves and protected areas, and we need more inter-connection between habitats. The larger reserves need to be managed more with habitat interfaces in mind, eschewing straight lines (other than natural ones) and accommodating as much intergrading and even shifting of habitat edges as possible. Much is being done already, of course. The Wildlife Trusts, The Grasslands Trust and others are increasingly looking at ‘landscape-scale’ conservation as a means to achieving greater connectivity and mosaic habitats. There are outstanding existing examples of dynamic mosaic habitats; the New Forest, for example is an extraordinary example of a large area full of dynamic natural habitat boundaries, though in recent years it has been rather too heavily-grazed to allow the full potential expression of its insect fauna. There are large reserves such as the Dorset Wildlife Trust’s Powerstock Common that are now being managed in this way, with wonderful results. But we need more, and we need more co-operation both within the conservation movement and with outside agencies that have an interest in the countryside. Boundaries between adjacent protected areas could be dismantled, and joint management undertaken. Joint purchases could be investigated – wouldn’t it be marvelous to have a Woodland Trust-Grasslands Trust reserve that encompassed old woodland grading into lovely flowery grassland, perhaps restored from degraded habitat? And perhaps, at the next opportunity, we could vote out the self-proclaimed ‘greenest government in history’ who are turning out to have so little sympathy for, or understanding of, the natural countryside, and replace them with something more sympathetic.