Principles of Ecological Restoration

The work of Trees for Life is helping to pioneer the techniques of ecological restoration, the newly-developing science of rehabilitating degraded and damaged ecosystems, or, in more simple terms, the healing of the Earth. Restoration work is underway in a wide variety of ecosystems, ranging from Costa Rica's dry tropical forests and the tallgrass prairies of the midwestern USA to the subtropical rainforests of New South Wales in Australia. From those diverse and wide-ranging situations, some common basic principles are emerging. Ecological restoration is based on the premise that 'Nature knows best', and is in fact a natural process which takes place normally in the absence of interference from humans. A good example of this is in the Mount St. Helens region of Washington State in the USA, where a large area of forest was devastated and blanketed by ash from the volcanic eruption there in 1980. Because the forest ecosystem surrounding the affected area is relatively intact, pioneer species have already colonised the land and the whole process of ecological restoration is occurring of its own accord. Ecological restoration is based on the premise that 'Nature knows best', and is in fact a natural process Just as our own human bodies have a self-healing ability which comes into effect when we cut or injure ourselves, so too does Gaia, the Earth organism, have the capacity to heal the 'wounds' which injure the organic ecosystems on her surface. However, in many situations now the scale and impact of human activities prevent this self-regenerating process of the Earth from taking place, so pro-active ecological restoration becomes necessary. In presenting these guiding principles here, we do not intend them to be a definitive and complete statement of ecological restoration. Instead, they are a 'work in progress' in that we, and others involved in this work, are learning as we go along, and nature still has much more to teach us.

Mimic nature wherever possible Work outwards from areas of strength, where the ecosystem is closest to its natural condition Pay particular attention to 'keystone' species Utilise pioneer species and natural succession to facilitate the restoration process Re-create ecological niches where they have been lost Re-establish ecological linkages Control and/or remove introduced species Remove or mitigate the limiting factors which prevent restoration from taking place naturally Let nature do most of the work Love has a beneficial effect on all life

1. Mimic nature wherever possible

It follows from the premise 'Nature knows best' that we should seek to mimic nature wherever possible when we work to restore degraded ecosystems. A simple example of this principle involves our programme of planting trees in Glen Affric. Under natural circumstances, the trees in the forest would regenerate by themselves but the artificially-high grazing levels maintained by human interests prevent this. So when we plant trees, we do so in patterns which copy the distribution of naturally-regenerating tree seedlings in the glen, and in the same soil types and topography as the trees grow in by themselves. This is in direct contrast to commercial tree planting, which is done in a linear fashion, and where the land is shaped (through ploughing etc.) to human needs.

2. Work outwards from areas of strength, where the ecosystem is closest to its natural condition

For ecological restoration to be most effective, it should begin in and spread outwards from sites where the ecosystem is as intact as possible. Under natural conditions, the ecosystem would expand again from such areas, as, for example, is widely believed to have happened at the end of the last Ice Age, when the tropical rainforests expanded to their present range from the refugia to which they had been confined during the drier climate of the glacial period.

Working outwards from the intact remnants of ecosystems facilitates the dispersal of insects, animals and plant seeds etc. into the adjacent areas being restored, and this minimises the amount of human intervention which is necessary. In Glen Affric, this principle is evident in our work through projects such as the fence at Coille Ruigh na Cuileige. This exclosure protects an area of 50 hectares on the periphery of a remnant of the Caledonian Forest, and the seed source provided by the mature trees mean there are an estimated 100,000 naturally-regenerating pine seedlings inside the fence, and therefore no need to plant any trees there.

3. Pay particular attention to 'keystone' species

In conservation biology, keystone species are ones which play a central, critical role in ecosystems, and upon which many other species depend. If an ecosystem can be returned to a state in which the keystone species flourish, then all the other species which depend on it will benefit as well. In the boreal component of the Caledonian Forest, such as the pinewoods in Glen Affric, the Scots pine is a keystone species. Therefore, by concentrating our efforts on Scots pines, we find that the whole forest community begins to recover. Another example of a keystone species, for riparian (or river-side) ecosystems is the European beaver, which through its dam-building creates micro-habitats of still water. These benefit certain fish species and promote the growth of aquatic vegetation, which in turn provides food for mammals such as the moose.

4. Utilise pioneer species and natural succession to facilitate the restoration process

When a forest community colonises an area of open ground, there is a process of succession which takes place, beginning with the pioneer species. These typically are fast growing short-lived species whose seeds are widely dispersed, and they eventually make way for slower growing, longer-lived species of tree. In the pinewoods, the main pioneer trees are birch, rowan (right) and aspen, all of which grow quickly, but only live for 100 years or so, in contrast to the slower growing Scots pines, which reach a much larger size and can live for 350 years. The pioneer trees draw up nutrients from the earth, which are returned to the forest floor when their leaves fall each autumn, thereby enriching the soil for the more nutrient-demanding successional species. By utilising the process of succession and pioneer species, we are working with nature, and a current example of this in our work is in the planting we will be doing in the almost totally deforested Carnach Mor area of West Affric this spring:- the species we are planting there (rowan, downy birch and eared willow) are all pioneeer species.

5. Re-create ecological niches where they've been lost

In degraded ecosystems the ecological niches which support species with specialised habitat requirements have often been lost. For example, with the conversion of natural forests into managed plantations of tree crops in many parts of the world there has been an almost total loss of standing dead trees (snags) or fallen logs, as they are seen as 'waste', and are removed or burned to make way for 'productive' growing trees. However, dead wood in the form of logs provides the habitat for many invertebrate species which are essential components of the forest ecosystem, while snags provide nesting sites for various types of birds.

The re-creation of lost ecological niches is therefore an important step in the restoration process, and a relevant example of this from our work in Glen Affric is when we fell areas of introduced non-native conifers. In a commercial situation, the felled trees would be 'extracted', but by leaving them to decompose where they fall, their nutrients are returned to the soil and a habitat is provided for a range of fungi, invertebrates and micro-organisms.

6. Re-establish ecological linkages - reconnect the threads in the web of life

An ecosystem is a community of interdependent species, all of which are necessary for the health and proper functioning of the whole. When ecosystems become degraded and disjointed, many of the ecological linkages or connections between populations or species are broken. A simple example of this is that the remnants of the Caledonian Forest are very fragmented and isolated, and in some cases where only a handful of trees survive, the gene pool, on which the long term health of the species depends, is now very small indeed. It also means that when species such as wood ants disappear from a forest remnant because there are not enough trees to support them anymore, it is extremely unlikely that they will get back there by themselves, even if the number of trees were to increase again, because the remnant is now so isolated from other forest areas.

While we haven't carried out any direct work to re-establish such linkages yet, we have organised studies of both wood ants and mycorrhizal fungi to discover whether specific action is needed to relocate them into areas of regenerating forest, but further research is needed before any definitive conclusions can be drawn.

7. Control and/or remove introduced species

All over the world ecosystems are being degraded, and their integrity (and in some cases their survival) threatened through the introduction of non-native, exotic species. Islands are particularly vulnerable to disruption from introduced species, and in the Galapagos Islands, for example, the endemic giant tortoises are seriously endangered by introduced goats, which eat their eggs. In Britain the native red squirrel has steadily decreased in range and numbers since the grey squirrel was introduced from North America. The control, or where possible the removal, of such introduced species is an important and essential element of any restoration programme for ecosystems affected by them.

In Glen Affric, the most obvious example of this is the work which we've been involved with since 1989 to fell the introduced non-native species of conifer. The removal of these exotics is in turn one of the most urgent and effective means of securing the regeneration of the Caledonian Forest.

8. Remove or mitigate the limiting factors which prevent restoration from taking place naturally

As mentioned in the introduction above, restoration of ecosystems is a natural process, which is often prevented by human interference. Removing the limiting factors can sometimes be all that is needed for restoration to be successful, without the need for other intervention to assist it.

In the Highlands of Scotland, the main limiting factor preventing the Caledonian Forest from regenerating itself is the excessive number of grazing herbivores, mainly red deer and sheep, which eat any young seedling trees that grow above the heather. A reduction in the number of grazing animals is a better approach to forest regeneration than erecting extensive, unsightly and expensive deer fences. On the Abernethy Reserve in the Cairngorms the RSPB is dismantling deer fences and relying on a heavy deer cull to achieve forest regeneration, but this approach only works where there are a lot of trees and the balance between grazing and seedling survival is not too far off. In an area like West Affric, where there are virtually no trees left, fences are the only viable method of achieving regeneration because the ecosystem is so far out of balance at present.

9. Let nature do most of the work

This principle is a logical extension of the premise that 'Nature knows best', and is essential if restoration is to achieve a wild ecosystem, rather than just another managed landscape. The misguided belief that humans can do it better, and that nature needs to be 'managed' is one of the main factors contributing to the present sad state of many of the world's ecosystems. This 'arrogance of humanism' as it has been called is in direct contradiction to the experience that nature, in five billion years of evolution on this planet, has produced ecosystems of whose sophistication and complexity we are only now beginning to get an understanding.

In practice, we are implementing this principle in our work through the establishment of small pockets or islands of new forest at strategic locations in the denuded landscapes of West Affric and other areas. When the trees in them reach seed-bearing age, we will rely on natural regeneration to restore the forest outside the exclosures, assuming that deer and sheep numbers have been brought down in the interim. Thus, we are in effect 'kick starting' the restoration process and then letting it develop by itself.

10. Love has a beneficial effect on all life

This is perhaps the one unique principle which we work with at Trees for Life, and it stems from the early experiences of the original Findhorn Community garden in the 1960s. Working with love and respect, in cooperation with nature, the gardeners were able to grow remarkably large vegetables and flowers. Anyone who has a 'green thumb' and grows especially beautiful houseplants or vegetables is also experiencing this.

This principle underlies all our work, as we know that love nurtures the life force and spirit of all beings, and is a significant factor in helping to heal the Earth. In some areas of Glen Affric we've found pine seedlings growing in the most unlikely locations, and we know that in some way that's connected with the quality of love which we, and others, bring to the ecological restoration work there.

See also Ecological Restoration Quotations

Published: "Trees for Life News" April 1996
Last updated: 25 August 2010