|Gardening for nature - management of our national nature reserves|
Even a competent gardener needs a certain amount of stoicism in the face of the plant failures that will come their way from time to time. The adage of the right plant in the right place is so simple but so often overlooked in the desire to achieve a particular effect, or to push a plant to survive outside of its normal range. Sometimes a plant will flourish for one season, but then disappear only to reappear a few years later. Mystifying as this could be, it does show that in spite of our best efforts, we are not always the one in control and that Mother Nature still gets to have her say.
While gardening is how we embellish where we live, you wouldn’t necessarily think that it is also a common practice in nature reserves, except that conservation professionals lack the candour to describe their actions as such. By any analysis, the helping hand they give nature is a process of selection and control that is equal in effect to what happens in any suburban garden. Except that what is an acceptable practice in a garden setting can seem very out of place in a nature reserve.
Lindisfarne National Nature Reserve (NNR) is a mix of tidal mudflats, saltmarshes and dunes along a long stretch of the Northumberland coast. (It is an SSSI that is also a Ramsar Wetland of International Importance, and a Special Protection Area for wild birds.) We like to visit the sand dunes on Holy Island in July when the dune slacks are packed with drifts of thousands of marsh helleborines. It is one of nature’s surprises in this arid landscape that the slacks or hollows can hold water all summer and that their wetland vegetation provides a striking contrast to the dryland species of the dunes.
An English Nature noticeboard proclaims that the dunes are home to 10 orchid species. We think we have seen five of them in flower over the years, and have got our eye-in for the rare dune helleborine that grows on the low dunes at the edge of the slacks. In recent years, the dune helleborines have been protected from rabbits by small individual enclosures of chicken wire, ensuring that they seed well. Ironically, the rabbits are praised in an English Nature leaflet as they are said to perform a useful function on the NNR in keeping down the characteristic creeping willow in the dune slacks, allowing many rarer plants to establish. Except that the creeping willow has been manually cut in recent years. And yes, dune helleborines have sprung up in the reduced sward of the dune slacks, more so than they have spread out on the low dunes. Is this a case of the dune helleborine changing its usual distribution? If so, will it now rely on our intervention for its survival?
I think it’s likely that the dune helleborine has suffered from the drier summers of late, reducing their presence on the low dunes, but gladly accepting the opened-up opportunity presented by the moisture of the gardened slacks. However, their continued survival in there is uncertain: would it become too moist in the slacks during a summer with usual rainfall (but never too moist for the marsh helleborine); can the dune helleborine there survive the regrowth and crowding out of the creeping willow? Unlike the abundant marsh helleborine of the dune slacks, the dune helleborine would seem to have a more precarious existence on the low dunes, ebbing and flowing in numbers as the summer’s weather unfolds. Perhaps we need to be more trusting of nature than impose our expectation upon it.
The high dunes expose the full horror of an invasive foreign plant. The pirri-pirri bur, a native of New Zealand, has a strong grip on the dunes, growing low under the marram grass and drifting rampageously down desire lines. The burs stick tenaciously to socks, trouser cuffs and boot laces so that seed transfer is guaranteed. We are always careful to remove all the burs as we leave so that we don’t transfer it ourselves.
The arrival of the pirri-pirri bur may be ill fortune, but the presence of another foreign plant in the dunes is a by-product of intent. You may think it inappropriate, but I think it bizarre, to come across masses of spiky dead Christmas trees lodged in the dunes, some of which still have their price tag. A plaque tells you that these dead trees represent the efforts of local schoolchildren in a project to stabilise the dunes. Thus a job-lot of unsold garden centre conifers have been enlisted to hold back the normal dynamics of the sand dunes, except that one has rooted and glows emerald green amongst the sinister and tangled deathliness of the rest.
Bradfield Woods NNR is an ancient woodland in Suffolk, praised for its tradition of coppice management that can be traced back to medieval times. The continuously coppiced hazel and ash have formed massive woody bases called stools that are cut on a 20-25 year cycle. The coppiced stems can be used for firewood, fencing and thatching spars. Scattered amongst the coppice are standard trees, allowed to grow for 60-100 years before being felled for timber.
Much is made of the wildlife value of this wood, but I have been underwhelmed about its overall feel on the occasions I have visited. Coppice regrowth produces dense bushy thicket that closes off the woodland so that there is hardly any forest interior habitat. This is reinforced by the internal fencing regime that means that although you enter into this woodland, you can’t walk through it, only around it, peering into the gloom from the rides. It is a highly artificial structure in which wildlife has to persist in spite of the management, except that of course the species that it favours are those that benefit from the gardening.
Perhaps the most serious criticism that can be levelled against coppiced woodland is the lack of accumulation of coarse woody debris. Historically, managers removed deadwood to protect woodland resources from insect and fungal attack. The amount of deadwood in coppiced woodland is thus very low so that there is no home for many woodland species. In natural temperate forests, decaying wood provides important habitat for small vertebrates, invertebrates, cavity nesting birds, and many lichens and bryophytes, bracket fungi and other saproxylic fungi (1). There is deadwood habitat on living trees as well: in the rot holes, dead branches and heartrot, each being a home to some plant or animal. In natural forests, droughts, storms, insects, disease and fire are the most important factors that can kill trees and create deadwood.
A sign at the Bradfield Woods reserve praises the flush of wildflowers that occurs in the first few years of a newly coppiced area. I’m not sure how you get to see this because of the fences that ring the newly coppiced areas, but negotiating a barrier, I walked into one of these only to find disturbed ground weeds, which pretty much summed up my experience of Bradfield Woods NNR.
The relationship between human practices and the behaviour of plants is many millennia old in Britain. Plants often need disturbance to an existing vegetation cover in order to become established. Thus in nature, the action of animals (burrowing, rootling, trampling, damming etc.) insects (ant mounds) river deposits, storm damage and fire are obvious examples, but increasing shade from a growing tree is a form of disturbance that favours change as well.
Today, the main source of disturbance arises from human practices such as grazing by domestic animals, felling, excavation and construction, and ground clearance of any sort. It is thus unsurprising that if you search through a wildflower book for the British Isles, many of the entries list waste or disturbed ground as the likely habitat in which you can find this wildflower. It may also say footpath edges, tracksides and weedy areas. As we have disturbed the land around us, the build up of these disturbed ground wildflowers has turned them into invasive weeds so that we no longer care what would be the natural habitat of docks, nettles or thistles, we just want them to stop following us around.
Beauty rather than ecological function is often how we decide whether a wildflower is a weed. We are perverse in our dislike of the ugly, disturbed ground species when instead we admire the charms of other disturbed ground wildflowers such as field scabious, even lamenting its decline. Field scabious is still common, but grazing and early cutting of hay meadows means that it often does not reach flowering stage. As you would expect, a bit of tinkering with the way that we farm – or habitat management as the conservation professional would call it – can reverse that decline and keep the field scabious as our fellow traveller.
Should we garden for nature? At what point is human intervention a natural influence - if at all – when we place ourselves alongside all the other species that have an influence on the planet? Eric Higgs is a Canadian who writes about ecological restoration. He recently reflected on a study that repeated a series of survey photographs of Jasper National Park in Canada taken in 1915 (2). As you would expect, clear differences can be seen in the expansion of the town of Jasper and the support service areas for the park and tourism. There are also striking changes in the vegetation of the montane valleys. Contemporary photographs show denser forest cover compared to the more open landscape of the earlier photographs. The few fields of the pre-park farmsteads are still clearly visible although attenuated, but traces of the open landscape mosaic of subsistence agriculture and trapping from that pre-park era are obscured by the new growth.
Higgs tells us of the Métis that dwelled in the valley (descendants from fur trapping and trading between Europeans and the Cree and Iroquois) and whose activities where a combination of the old of first nation practice and the new of the Euro-American economy. With the displacement of the Métis from the park, the rate of change in the landscape was accelerated, giving rise to what Higgs polemically terms as “freak landscapes” because they had lost an influencing force that existed before the park was set up.
As he says, it begs the question as to whether human influence can ever be regarded as normal – or at what point in past history did it become abnormal. We do not have the luxury in Britain that Higgs had of making observations on a landscape ecologically much closer to a pre-agricultural, “first nature” state – something that our landscapes haven’t seen for thousands of years. We have yet also to see the effect of withdrawing our influence on a large scale, as he was able to observe from when the Jasper National Park was first set up. In its place, we lack the serious critical self-analysis that would have us reflecting on our behaviour in nature conservation. Without that, we will continue with interventions that set up a management responsibility to keep those gardened ecosystems within a narrow range of variability, and thus have them dependent on us for ever.
Mark Fisher, 17 August 2006
for instance, Ecological features of the Caledonian Forest - Dead