Journal American Society of Mining and Reclamation, 2013 Volume 2, Issue 2

UNDERSTANDING AND DELIVERY OF THE COMPONENTS OF STRUCTURE, DIVERSITY, AND FUNCTION IN THE RESTORATION OF ON MINED LAND: WORKING TOWARDS A PRACTICAL METHODOLOGY1

R. N. Humphries2

Abstract: With the full implementation of the Convention on Biological Diversity (CBD) by 2020, surface mining and other industries in the UK will have to embrace the concept of ecosystems and services, and be ready to deliver satisfactory schemes with all the necessary elements where important natural vegetation and are involved. It is debatable whether there is sufficient understanding of the ecosystems being considered and clarity in what needs to be achieved leaving practitioners and regulators with little guidance when faced with designing or evaluating a mining proposal or the evaluation of the success of restoration schemes. This paper introduces and examines a measurable and workable methodology based on the Tansley concept of vegetation communities (being the basic unit of ecosystems) and the application of the national monitoring standards (CSM) for the key requisite ecosystem structural elements. These are encompassed in the proposed Canopy-Age-Regeneration-Genetic-Indicator–Exotic design and assessment model. It is argued that the Joint Conservancy Council (JNCC) derived CARGIE Model is applicable to the restoration of ecosystems in the UK. It could enable better design and evaluation of the restoration of ecosystems and their services, and the mining industry to meet the challenges posed by CBD and the new and emerging legislation and policies.

Additional Key Words: biological diversity, ecosystem services, vegetation classification, plant traits ______1. Paper presented at the 2013 National Meeting of the American Society of Mining and Reclamation, Laramie, WY Reclamation Across Industries, June 1 - 6, 2013 and accepted for the online Journal of The American Society of Mining and Reclamation, Volume 2, No. 2, 2013. R.I. Barnhisel (Ed.) Published by ASMR, 3134 Montavesta Rd., Lexington, KY 40502. 2 Neil Humphries, Environmental Co-ordinator, Celtic Energy Ltd, Castlegate Business Park, Caerphilly, CF83 2AX, UK. and Visiting Professor, National Soils Research Institute, University of Cranfield, Cranfield, MK43 0AL, UK. Journal American Society of Mining and Reclamation, 2013 Volume 2, Issue 2 pp 1-31 DOI: http://doi.org/10.21000/JASMR13020001

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Introduction

Human kind, for good reason, has become increasingly preoccupied with the (bio-) diversity component of ecosystems; particularly in respect of the loss of rare species and the degradation of life supporting ecosystem services that living entities provide. The consideration of ecosystems is now beginning to determine how we exploit sustainably the natural resources of Planet Earth and consequently the consenting of future mine developments and the detailing of their reclamation.

By 2020 planning authorities and regulators in the UK will have had to review the impact and mitigation of development and management of natural resources and to have had fully implemented the Convention on Biological Diversity (CBD). This involves the enactment of legislation and policy to protect, enhance, and restore ecosystems and ecosystem services (Department of Environment, Farming and Rural Affairs, 2013). Surface mining and other industries in the UK will have to embrace the concept of ecosystems and ecosystem services, and be ready to deliver satisfactory restoration schemes with the recognised ecosystem elements.

Whether we have sufficient understanding of the ecosystems being considered and clarity in what needs to be achieved may be debated for some time to come. Whilst there is growing enthusiasm for a more ecological approach to restoration, we are seemingly stumbling around for clear guidance beyond repeatedly rehearsing “what a good thing this might be.”

This paper is concerned with the re-establishment of semi-natural ecosystems on mined land in the UK and to determine if there are useful and guiding principles that might be put to practical and beneficial effect. An outcome could be measurable and workable criteria to enable better design and evaluation of the restoration of semi-natural ecosystems and their services, thereby enabling the UK mining industry to meet the emerging challenges posed by CBD.

The Ecosystem Concept

Over the millennia, globally, there has become a myriad of species at both the macro- and the microscopic scales within the same abiotic environments, and even the of biotic ecosystems within ecosystems (Thompson, 2010). In the simplest of terms, the conceptual definition of an ecosystem is a (biotic) community of living entities (comprising of individuals and populations of animals, plants, fungi, bacteria species) within a non-living (abiotic) environment (Odum, 1963). The concept embraces a bewildering range and complexity of living entities across

2 Journal American Society of Mining and Reclamation, 2013 Volume 2, Issue 2 a range of spatial scales from continental coral reef systems to the microscopic level of microorganisms and protists of soil aggregates. Some systems are temporal in nature, such as the migratory Caribou with spatially different supporting communities depending on season.

The search for a unifying understanding of ecosystems and its application to the sustainable exploitation of natural resources developed considerably in the 1950s and 1960s with the study of energetics and trophic structures and functions (Odum, 1963). This was followed by studies of the dynamics of interactions between individuals and populations from the 1970s (e.g., Harper, 1977) through to today.

The conceptual structure and function of the biotic component of ecosystems is based on a pyramid of trophic levels (Odum, 1963), comprising populations of producers () and consumers (heterotrophs - including predators and ). For any particular ecosystem there are populations of associated plants, fungi, bacteria, and animals. For these to exist and function there are a number of fundamental life cycle processes comprising immigration, establishment (niche), growth and development, and reproduction and dispersal (Harper, 1977). This is further embellished through genetic differentiation in terms of competitive ability through life form and phenology, physiological adaptation to environmental and biotic (disease, predator) stresses, and and resource availability (Grime et al., 1988).

The complexity of the topic makes it a seemingly impossible task to marshal a workable approach to grasp and apply in practice. So is there a pragmatic way forward to this conundrum? A possibility is to define the scale the reclamation approach needs to work. To this end, the thinking of Arthur G. Tansley (the reputed originator of the term ‘ecosystem’ (Moore, 2012) is most helpful. He used the term ecosystem to form a rational system for vegetation succession from pioneer (pre-sere) or secondary (sub-sere) stages to climax/plagio-climax stability between its plant (), animal, and (heterotroph) components. The merit of this definition of ecosystems and their complexity is the easily recognisable scale of plant vegetation communities (e.g., beech woodland, basic grasslands, dry heaths (see Tansley, 1949). It is at this scale and complexity that the restoration of ecosystems on mined land is considered further as a practical way forward for reclamationists.

The Restoration of Ecosystems

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John Harper (1987) aptly likened ecosystem restoration to repairing a damaged watch. To do this he considered the repairer needed “… a kit of parts and knowledge of how to fit together” and “… if this is done properly the watch will have acquired the emergent property of the whole ….”

Harper’s parts are synonymous with Odum’s structure and how they fit with his functional element. Magnuson et al. (1980) proposed a simple two-dimensional graphical model for the restoration of the Great Lakes’ aquatic ecosystems, which predicted spatially the outcome between structure and function (Odum, 1963). Bradshaw (1987) adopted his approach to illustrate the hypothetical directional development of restored and replacement terrestrial ecosystems. Here, he defined structure as species and/or complexity and function as and/or nutrients, and worked as follows:

• Degraded ecosystems are low in species complexity and therefore low in biomass/nutrients • Original ecosystem are high in species complexity and therefore high in biomass and/or nutrients • Degraded ecosystems recover through natural processes to the original by increasing in species complexity and therefore biomass and/or nutrients • Ecosystems are restored when they have the same level and balance in species complexity and biomass and/or nutrients • Other (replacement) ecosystems increase in level of species complexity and biomass and/or nutrients, but in a different balance to the original In the absence of further elaboration or definition, these might be taken as being representative of species number and trophic levels/ for structure and carbon assimilation, sequestration, and capacities for function. Bradshaw goes on to describe how the development from a degraded (low level) ecosystem to a restored (high level) ecosystem can be driven in the reclamation process through increasing the biotic structure by adding species and increasing ecosystem function by such measures as soil replacement, physical treatment, nutrient addition, and treatment of toxicities. If we take literally what this suggests, all that is required is to simply provide the requisite species and ensure the abiotic environment is not limiting to restore a particular ecosystem.

Burger (2012) in his recent paper on ecosystem reclamation and mining made similar suggestions based on the Bradshaw principles. Here, , habitat and water quality (as structural elements); and biomass/carbon accumulation, hydrologic function, flood control, etc.

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(functions) could contribute to higher levels of ecosystem reclamation where practices of geomorphic-landform design, replacement of topsoil, stream reconstruction and reforestation were implemented. In commenting on the general achievements of ecological and ecosystem restoration, Thompson (2010) considered that the restoration practices for the abiotic (physical) environment to have been largely perfected. This, in his view, was in contrast to the biotic element (particularly biodiversity). Given an apparent consensus there is sufficient knowledge to specify the required abiotic environment, this raises the question, what are the essential biotic structural elements in reclamation schemes? If the ecosystem structural elements are reassembled properly, then so will their functional elements, and the ecosystem and its services as a whole.

Developing a Methodology

Three temperate ecosystems are explored below as to their biotic structural elements at the plant-community scale and their application in the design and implementation of mine restoration schemes, and the assessment of the ecosystem restoration achievement. The three temperate ecosystems considered are woodland, a dwarf shrub heathland, and upland acid grassland.

Woodland Ecosystems In considering the application of Tansley’s vegetation-community-based ecosystem approach, the overreaching functional parts of mature woodland communities are essentially the autotrophic tree, shrub, and ground-layer vegetation components. The structural elements being vegetation height, density, growth form etc., which create and modify microclimate (humidity, temperature, and light), and provide food and breeding habitat providers for a range of heterotrophs and decomposers. In terms of woodland ecosystems, this embodies an array of structures and functions at the species level (Morris and Perring, 1974). In order to apply as a set of design and monitoring principles in the practical world this needs to be simplified.

Tansley’s structural model of woodland vegetation types, the vertical spatial distribution of the component higher plant species (i.e., horizontal canopy layers of tree, shrub, field, and ground layers) is obviously simplistic in that it overlooks the belowground components. Despite this it has been subsequently refined over the past decades to be more representative of the complexity of woodland ecosystems by introducing additional structural elements such as tree-layer, age class, regeneration potential, genetic pool, local features, and the presence of exotic, alien or weed species (Table 1). This six-element structural model has been adopted by the UK Forestry

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Commission in their surveys to compile the National Inventory of Woodland and Trees (Forestry Commission, 2001). Importantly, it has also been used by the UK Government’s scientific and oversight advisory body, the Joint Nature Conservation Committee (2004), in setting management actions/targets and monitoring of statutory protected internationally and nationally important woodlands in the UK. The following discussion considers the application of the JNCC derived Canopy-Age-Regeneration-Genetic-Indicator-Exotic model (referred to subsequently as the CARGIE Model) in the reclamation of terrestrial ecosystems using Sessile Oak woodland.

Table 1: Canopy-Age-Regeneration-Genetic-Indicator –Exotic Model for Restoring Woodland Ecosystems Structural Elements Definitions* Canopy Cover: Has a range of 30-90% of canopy cover for the tree layer with an understory cover of 20% of the total stand, and with a minimum of 10% open space. Age Class: A range of age classes (seedlings, saplings, young trees, mature trees, decaying trees, dead trees) where, at least three age classes are to be represented by the commonest trees with 10% or 5-10 trees/ha of commonest mature tree species represented by old growth (>150 years for deciduous species, >110 years for coniferous species) and a minimum 3 fallen trees of >20cm dbh and 4 dead standing trees per hectare. Regeneration Potential: Strictly as the capacity of the woodland’s main structural tree species to produce and regenerate from seed and to develop to sapling class. Age maturity …. Seed bearing years Genetic Pool: Not less than 95% cover in any structural layer to be solely native or naturalised species, and local provenance where local variations. Indicators of Local Distributions: Characteristic local micro-habitat features (other than dead wood), presence of notable species (other than tree species) to maintain distinctive local woodland characteristics. Exotic / Alien and Weed Species: No prescribed limits. Exotic/alien weed species eg Rhododendron spp to be progressively eradicated.

*Source – Joint Nature Conservation Committee, 2004

Sessile oak woodland (Quercus spp – Betula spp – Deschampsia flexuosa woodland, National Vegetation Classification type W16, Rodwell, 1991a) is one of several types of lowland woodland occurring typically on ranker, brown-podsol and podsol soils in the warm-dry conditions of south eastern UK. The mature woodland comprises tree, shrub, and herbaceous ground layers having a range of number of species (3-29) present. The constant characteristic tree layer species are either Sessile Oak (Q. patraea) or Pedunculate Oak (Q. robur) and Silver Birch (Betula pendula) or Brown Birch (Betula pubescens). The shrub layer is typically Holly (Ilex aquifolium) and Rowan

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(Sorbus acuparia), with a ground layer of Wavy Hair-grass (Deschampsia flexuosa), Bracken Pteridium aquilinem), Bilberry (Vaccinium myrtillus),Broad Buckler Fern (Dryopteris dilatata), Heather (Calluna vulgaris), and Bramble (Rubus fruticosa agg.).

Typically, these woodlands are of some age and the sites having been woodland for 200 years or more, with some examples predating Medieval times. In the UK, these woodlands have not gone unmodified and have historically been a source of timber on an ad hoc, a rotational or coppice basis, livestock grazing and hunting, and even as parts of a planned landscape (Marren, 1990). Others have been clear-felled and replanted from time to time. The oak trees are usually of some stature, but at a low density and often seemingly even-aged, which reflects the woodland’s history and exploitation. Where coppiced, the stools are of some size with the regrowth multi-stemmed, even-aged stems. Oak is usually the dominant mature tree species, but can be co-dominant with Birch or in some places Birch is the dominant (especially with clear felling and the opening up of the woodland canopy). In these woodlands canopy cover is usually not complete and characteristically comprise areas of ‘high wood’ with open areas (glades) and a high degree of woodland edge.

The following applies the CARGIE Model (Table 1) as the requisites for having established a Sessile Oak Woodland ecosystem on mined land. The five structural biotic elements are to be the essential part of the delivery by the reclamation design and a means for an evaluation of success.

Canopy Cover: According to the CARGIE Model, the requisite for this structural element of woodland ecosystems is the provision of 30-90% ground cover by the canopy (leaf cover) of the main constituent tree layer characteristic of the target woodland type (comprising of Birch and Oak in the example of Sessile Oak woodland being used as a reference example here). The widely qualifying range of canopy cover could be made up of any or combinations of the prescribed age classes of the Oak and/or Birch tree species. The primary purpose of the canopy cover is to provide the light and humidity conditions required for a woodland ecosystem function and diversity of associated woodland flora and fauna. It also provides for the conditions conducive for woodland regeneration (i.e., establishment of seedlings and maturation of seedlings).

For the shrub layer (Holly and/or Rowan in the Sessile Oak woodland) there is a requirement for a 20% canopy cover relative to the whole stand. The distribution of this qualifying element can be at the woodland edge, scattered, and/or clumped within the woodland. The third requisite

7 Journal American Society of Mining and Reclamation, 2013 Volume 2, Issue 2 is the 10% open space within the woodland as a whole, which may take the form of scattered glades or larger areas.

This structural element of woodland could be provided by the design of the reclamation scheme; for example, for an area of 100ha of woodland, 90ha would be wooded and the overall tree canopy cover (of the main community tree species (Birch and Oak in the Sessile Oak woodland) would be between 30 and 90%. Within the wooded area as a whole 20ha of shrub layer canopy and 10ha of open space could be provided. The tree and shrub-layer canopy cover criteria could be achieved in a number of ways, either by planting and/or sowing the component woodland tree and shrub species or by leaving woodland regeneration to natural colonisation (where there is a nearby and certain source of propagules and the required species have sufficient dispersal mechanisms).

Where planted, compared with relying on natural colonisation, the tree and shrub canopy cover can be rapidly and predictably achieved through planting design and specification (stock size and planting density), and species growth habit and performance. For example for Birch – Oak woodland with a qualifying canopy cover criteria can established within five years as described by Humphries and McQuire (1994a). Where dense planting is relied upon, the understory can be provided in the woodland design as edges and openings. The attainment of open space can also be delegated as a matter of design and achieved without difficulty.

In the UK, planted schemes are typically managed under planning consent agreements by standard forestry practices (see Evans (1984) and Hibberd (1986)) for the first 10-20 years, and thereafter, under the owner’s or tenant’s stewardship, to achieve the intended use (e.g., timber, catchment management, recreation, wildlife, or as visual landscape treatment). Here, density of stems and canopy cover may be reduced or nurse species removed to alleviate and facilitate tree and shrub maturity, and provide space for understory and ground layer development. This is achieved by a cyclic programme of thinning, whilst maintaining tree and shrub canopy cover.

Where there is reliance on seeding, the time to reach the required canopy cover will be longer and maybe less predictable and more so where natural colonisation is relied upon. If a specific woodland composition and structure is required, subsequent intervention by managing species composition and density may be necessary.

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Age Class: To meet the qualifying requirement of this second CARGIE Model element there needs to be the presence of at least three of six prescribed age classes (see Table 1) of the characteristic tree layer species (i.e., Birch and Oak in the example being used here). This is primarily to provide important physical habitat structure and conditions, and a range of food sources for the diverse assemblage of woodland flora and fauna. In this respect three age classes are particularly important for woodland ecosystem function and diversity, these are: the sapling growth stage, maturation to seed-bearing age, and old growth (particularly fallen/standing dead trees) of the tree layer species.

In the design of restoration schemes either a spectrum of age classes are to be introduced at the time of site reclamation, during the ‘aftercare period’ or later during the first complete life cycle of the trees within the woodland. In application of this age-related structural element, qualification would only be achieved with the manifestation of three or more classes within the woodland.

Taking the sapling, seed bearing aged trees, and old growth classes as examples the following might be considered. The sapling age class in reclamation schemes can be quickly achieved (typically 5-10yrs) by planting young nursery stock (as is standard practice in the UK (Moffat and McNeill, 1994), but thereafter it takes a number of decades (depending on species) to reach the next mature stage (Evans, 1984). As the sapling cohorts mature into the next older classes in the course of the development of the woodland, either further replacement saplings will be required for this age class aspect of woodland structure to be maintained or a different age class will need to be present as a replacement. The next cohort of saplings could be provided by further planting of young trees or recruited from seed and seedlings. The former would require intervention at some point during the development and maturation of the woodland. This may be several decades after the initial planting. The latter could also be by intervention through introducing seed of the tree layer species to the woodland or reliance on the maturation of the tree layer species (Birch and Oak in this example) to produce seed from which seedlings mature into the replacement saplings. However, in the latter case, the time before the first cohort of planted trees matures sufficiently to produce seeds and provide their own seedlings is a matter of decades. For Birch it is typically 15 years and for the Oak species it is 40 or more years (Hibberd, 1986). The provision of the old/dead wood element from the first cohort of trees will be considerably longer, being in the order of 50- 60 years for Birch and 200 or more years for the Oaks (Evans, 1984).

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In the interim decades before the Birch and Oak mature to produce seed and dead wood, these two missing aspects of the woodland ecosystem might be catered for by intervention to provide these age class structural elements and contribute to the early development of the woodland ecosystem. Seed could be periodically sown or young trees planted during the early development of the woodland to provide cohorts of the sapling age class. The provision of fallen dead trees and upright decaying wood could be provided from areas of the mine development being clear-felled as part of the forestry programme in advance of mining or felled or from restored areas being thinned as part of the aftercare management. The timber could then be stored for later reintroduction. Felled timber can be planted to satisfy the requirement for upright dead wood. In some situations it may be possible in the wider mining plan to provide seed bearing trees and mature/over-mature trees by translocation or through leaving islands or corridors of existing mature woodland. In ecosystem restoration terms, the crucial seed, sapling, and dead wood age classes and their contribution to the vertical structural components of the woodland ecosystem could be provided within a 15-20 year period for Birch dominated woodland and 50 years for Oak dominated woodland. Where woodland is established by seeding or to rely on natural regeneration will take longer to generate the qualifying tree canopy cover because of slower immigration and establishment rates.

In applying the age class structural criterion, the type and amount of old growth is quantified as the provision of fallen and dead trees at three and four per hectare respectively, whereas the amount of saplings and seed production is not, and is related to the next structural element of the potential of the woodland to regenerate.

Regeneration Potential: A key characteristic of ecosystems is their ability to re-new and regenerate their constituent populations. In principle, this qualifying criterion is satisfied by showing that the complete life-cycle processes are operational (as without this ability other vegetation and ecosystems will develop). In the case of woodland, regeneration is typically by seed with the regeneration potential being simply a function of the presence of the key tree canopy species and the time it takes before they become seed bearing as set out above. There will have to be a sufficient number of trees to provide an adequate amount of seed and sufficient number of seedlings that provide the necessary replacement saplings and mature trees for the required canopy cover to persist. In terms of the amount of seed produced and number of saplings needed for woodland regeneration, this is dependent on many factors including seed viability and dormancy,

10 Journal American Society of Mining and Reclamation, 2013 Volume 2, Issue 2 and disease, available suitable niches, etc.. Whilst the qualifying criterion in Table 1 is not quantified in terms of numbers, density, or distribution, it would be expected that the saplings and maturing trees would be apparent throughout the woodland and capable of providing further mature/over-mature trees in due course.

Whilst the age class structure is informative of the regeneration potential of woodland ecosystem restoration schemes, cognisance needs to be given in the design and specification to the timing and amount of seed production by the first cohort of tree layer species planted. In practice, this may be a case of ensuring there are a sufficient number of trees (in locations where seed establishment is likely to be favoured) and a balance between generally uniform or clumped distribution to promote the chances of pollination, seedling establishment, and ultimately the replacement of the trees contributing to the woodland. In the early years of woodland restoration, regeneration could be promoted through intervention by periodic supplementary planting and/or seeding (in concert with other interventions to diversify the woodland’s age class structure as described above).

Genetic Pool: Reliance on foreign sources of seed and nursery plant material for the supply of ‘native’ species has meant that alien elements have been introduced into the UK gene pool over the past decades. Because of recent concerns for the conservation of species’ resilience and diversity, and introduction of diseases and pests, the genetic pool is now considered and specified at regional/local levels for the sourcing of seed and nursery plant material for reclamation schemes. This has resulted in the purposeful collection of seed and growing-on of local plants for some schemes and particularly where there is sensitivity of introducing non-local gene pools into the local landscape. Where woodland establishment relies on natural regeneration, it may be assumed that this will probably comprise of local gene pools.

Indicators of Local Distribution: Within the overall woodland ecosystem matrix of canopy cover of the main tree layer, range of age classes, and genetic pools there is a range of woody and non-woody species to be found giving distinct regional and local woodland characteristics. In the UK, there are twenty-five recognised semi-natural woodland and scrub community types (Rodwell, 1991a). Of these, there are four Oak Woodland types. Taking two Sessile Oak woodland types (NVC W16 and W17 (Rodwell, 1991a)) as examples, these woodlands in the UK have distinct ‘lowland’ and ‘upland’ Oak-Birch forms, Quercus spp - Betula spp - Deschampsia

11 Journal American Society of Mining and Reclamation, 2013 Volume 2, Issue 2 fexuosa (NVC W16) and Quercus petrea – Betula pubescens – Dicranium majus (NVC W17, Rodwell), respectively. The former W16 type is widespread through the relatively warmer and drier central, south, and east parts of the UK whilst the W17 type is typical of the cooler and wetter western and northern uplands of Wales and Scotland.

Within both types of Oak Woodland there are local variations in species composition of the shrub and ground layers giving two distinct types of W16 (largely soil and/or climate variants) and four types of W17 (largely climatic with oceanic and continental variants) and each variant has its own indicator species (see Rodwell, 1991a). The example referred to above in this paper is the W16a Quercus robur sub-community with an of Bracken over a Wavy Hair-grass sward, but no particular indicator species, whereas W16b has a number of associated moss indicator species (e.g., Isopterygium elegans).

In the design and specification of reclamation schemes cognisance needs to be given to the woodland composition and to the local indicator species. At the wider regional level, Rodwell and Patterson (1994) provide a list of species that can be selected from. It would be expected that the restored woodland ecosystem would have the appropriate compositional elements.

Exotics and Aliens: In designing mine restoration schemes in the UK there has been a move away from the use of non-native species. Their use in the past was largely because methods of establishing native species on disturbed soils and mine wastes, was little understood and the non- natives were sometimes easier to establish. With the development of mine restoration practices this is no longer necessary and besides the national nature conservation policy is now firmly against introducing further alien species following their detrimental effects on native woodland and other native ecosystems (UK Parliamentary Office of Science and Technology, 2008). Some tree species like Sweet Chestnut (Castenea sativa) and Sycamore (Acer pseudoplatanus) were introduced into the UK some 2000 years ago by the Romans. They are regarded as being naturalised in the UK landscape, although these and others are often regarded as being detrimental to native woodlands (Pearman and Walker, 2009). Many of the commercial conifer crop species are non-native and of North American origin and may be regarded as becoming ‘naturalised’ in turn. In terms of restoration of non-coniferous commercial plantations, it is now typical that only native dicotyledons and conifer tree and shrub species are to be established.

Dwarf Shrub (Heathland ) Ecosystems

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The same Tansley based CARGIE Model principles described above for woodland can be applied to other ecosystems. Here, the reclamation of Heather (Calluna vulgaris) dominated heathland (as an idealised model for shrub ecosystems) is considered. The same Joint Nature Conservation Committee (JNCC) source of vegetation monitoring information (as for woodland) was referred to for the key structural elements for dwarf shrub ecosystems. For the dwarf shrub communities (JNCC, 2009a) the information is presented in a different format from that for woodlands (JNCC, 2004) and had to be extracted, and compiled in the woodland format as set out in Table 2.

Calluna dry heathland (Calluna vulgaris – Deschampsia flexuosa heath, NVC H9 Rodwell, 1991b) is one of several types of lowland heathland occurring in the UK. It is typically associated with free-draining, strongly acid (pH 3 - 4) and base-poor, shallow ranker soils or highly leached deep brown soils and typically on the Permian-Triasic Sandstones soils at low and moderate altitudes in the cool and wet parts of central and north-central England. Mature dwarf shrub heathland comprises shrub and herbaceous ground layers with a typical range in number of species from 2-21. The constant shrub species is Heather (Calluna vulgaris) and the ground layer Wavy Hair-grass (D. flexuosa) and the Nodding Thread-moss (Pohlia nutans). Typically these heathland areas are of some age and may have originated from past woodland clearance and maintained by the subsequent introduction of burning and grazing (Webb, 1986). This type of heathland is often exploited commercially for its grazing and sporting returns.

Table 2: Canopy-Age-Regeneration-Genetic-Indicator –Exotic Model for Restoring Dry Dwarf Shrub (Heathland) Ecosystems Structural Elements Definitions* Canopy Cover: Shrub canopy cover of 25% - 90% comprising of at least two ericaceous species, with <50% Gorse cover, a ground cover of <25% - 30% graminoids-forbs-lichens & bryophytes, and 1% - 10% bare ground. Age Class: A range of growth phases for ericaceous species: Pioneer 10-40%; Building/Mature 20-80%; Degenerate <30%; Dead <10%.

Regeneration Potential: Strictly as the capacity of the heathland’s main structural dwarf shrub species to produce and regenerate from seed Genetic Pool: Not less than 95% cover in any structural layer to be solely native or naturalised species, and local provenance where local variations.

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Indicators of Local Distributions: characteristic local micro-habitat features, presence of notable species to maintain distinctive local dwarf shrub community characteristics. Exotic / Alien and Weed Species: Less than 1% alien or weedy species; <5% Bracken; <10% trees or scrub

*Source JNCC, 2009a

Canopy Cover: In the case of the NVC H9 dry heath community, there is only one CARGIE Model qualifying shrub, Heather, with a requirement for a canopy cover of between 25 and 90%. The ground layer is to have up to 30% herbaceous ground cover and 10% bare ground.

In dwarf-shrub restoration schemes in the UK the shrub layer is established from sown seed, although in some cases natural colonisation may be relied upon where there is an adjacent seed source. The ground layer may or may not be sown.

Age Class: The dwarf shrub component is relatively short-lived (typically 30 years). Four age classes are recognised in dwarf-shrub heath ecosystems, these are: the pioneer, building/mature, degenerate, and dead stages (Gimingham, 1972). Unlike woodland, the main source of dead plant material is the accumulated leaf litter beneath the shrubs.

To qualify for the age class CARGIE Model criterion, the definition requires that all four growth phases are to be present at the same time. Individual stands of these heaths tend to be monocultures of the pioneer and building/mature phases in their physical form due to cyclic management (burning) to promote their grazing and sporting (game birds) value. Hence, the implied structural-mix occurring at the same time in these ecosystems may not be met in practice in individual stands. However, where either less formal management is implemented or the heath left to natural processes as in nature conservation areas, it would be expected there would be more than one age class present.

In restoration schemes (where the heaths are not being commercially exploited) the spectrum of age classes can be provided by either a phased cycle of establishment or differential management (e.g., localised cutting/burning) over a period of 10-15 years. Areas of established heath left without intervention of grazing or burning are readily invaded by tree and shrub species and rapidly become scrub and woodland.

Regeneration Potential:

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This structural element is not defined in the JNCC monitoring guidance. However, the key to regeneration of the dwarf shrub heath is the production of seed and open habitat (bare ground with little litter). Flowering and seed production occurs early in the life cycle of Heather and is at its maximum during the building/mature phase. In restoration schemes, management programmes can be devised to promote these phases.

Genetic Pool: Whilst no JNCC guidance is given as to criteria for this structural element, it would be expected that strict conservation of local genetic gene pools would be required. Seed in the UK is typically sourced locally by harvesting from existing stands (as part of wider heathland management programmes).

Indicators of Local Distribution: In the UK twenty-two dwarf-shrub (heathland) community types have been described (Rodwell, 1991b). Like the woodland vegetation types, all the types of dwarf shrub heathland have distinct regional and local characteristics, some of which are extremely localised. For example, NVC H5 Erica vagans – Schoenus nigricans heath is restricted to the Cornish Lizard in the far southwest of England. Here, the Cornish Heath (E. vagans) would be an indicator species as it is endemic and not found elsewhere in the UK. Whereas, the NVC H9 covers tens of square miles over the southern Pennines and North York Moors. The latter has five recognised sub-community types with their own characteristics and indicator species. For the regional variant example in central-east of England (the Galium saxatile sub-community) Lady’s Bedstraw (G. saxatile) and Tormentil (Potentilla erecta) would be indicator species.

Hence, in reclamation schemes in the above localities it would be expected E. vagans would be present for schemes on the Cornish Lizard and other species to be present in schemes in the central England, these being introduced by sowing, or planting, or colonisation.

Exotic / Alien and Weed Species: The JNCC guidance is prescriptive regarding this structural element where the heathland is to have less than the prescribed number/cover of alien or weedy species, bracken and trees/scrub.

These are generally post-reclamation management issues and are controlled by grazing or burning. The intensity of such programmes depends on whether the heathland is being exploited or left to natural processes.

Upland Acid Grassland Ecosystems

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The same Tansley based CARGIE Model ecosystem principles described above for woodland can also be applied to grassland ecosystems. Here, the reclamation of upland acid grassland (as an idealised model for grassland ecosystems) is considered. The same JNCC source of vegetation monitoring information (as for woodland) was referred to for the key ecosystem structural elements. For the upland habitats (JNCC, 2009b) the information for acid grassland was presented in a different format from that for woodlands (JNCC, 2004) and had to be extracted and compiled in the woodland format as set out in Table 3.

Sheep Fescue – Common Bent (Festuca ovina – Agrostis capillaris – Gallium saxatile grassland, NVC U4, Rodwell, 1992) is one of several types of upland grassland occurring in the UK. It is the most extensive type of pasture in the sub-montane cool, wet climate zone of Britain and typical of acidic podsol and stagnogley soils. The typical range in species is 7 to 62. The constant species are Common Bent (A. capilaris), Sweet Vernal-grass (Anthoxanthum odoratum) and P. erecta with Sheep Fescue (F. ovina) and G. saxatile. These grasslands are exploited for stock rearing and particularly as summer sheep pastures.

Canopy Cover: In the case of grasslands, the requisite canopy cover is concerned with the herbaceous ground layer. Here, the JNCC guidance is prescriptive for the grassland canopy to be dominated by grass species (70% – 80%). In the case of NVC U4 grassland this can be a mixture of A. capilliaris, A. odoratum, and F. ovina along with 10% forb cover comprising G. saxatile and/or P. erecta or other U4 characteristic species, and up to 10% bare ground.

In grassland restoration schemes in the UK the grassland is established by seeding, although natural colonisation may be relied upon where there is an adjacent seed source.

Table 3: Canopy-Age-Regeneration-Genetic-Indicator-Exotic Model for Restoring Acid Upland Grasslands Ecosystems Structural Elements Definitions* Canopy Cover: Less than 10% cover tree or scrub/Bracken canopy layers Ground cover 70% - 80% graminoids with 10% forb species, variable sward height range 1-25cm, <10% bare ground.

Age Class: Greater than 25% mature flowering to be more than 5cm height above the ground surface & >25% non-flowering maturity to be less than 5cm height above the ground surface, <10% dead material as litter layer Regeneration Potential: Strictly as the capacity of the grassland’s main structural species to produce and regenerate from seed and/or vegetatively

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Genetic Pool: Not less than 95% cover in any structural layer to be solely native or naturalised species, and local provenance where local variations. Indicators of Local Distributions: Characteristic local micro-habitat features presence of notable species to maintain distinctive local dwarf shrub community characteristics. Exotic / Alien and Weed Species: Less than 1% alien or weedy species; <5% Bracken; <10% trees or scrub <1% neutral grassland species, <10% Soft Rush <25% weed species *Source – JNCC, 2009b

Age Class: Although not set out in these terms, it appears from the JNCC monitoring guidance that there are three structural age classes, non-flowering pre-maturity, mature/flowering, and dead material. To qualify for the age class criterion (using the CARGIE Model) all three class have to be apparent and not less than the thresholds given in Table 3.

Unlike the productive neutral grassland types (Rodwell, 1992), these upland short-sward grasslands are not usually suitable for haymaking. Consequently, where these grasslands are used by commercial farming enterprises as pasture, they are grazed for much of the growing season and it is unusual to find flowering stands. However, like the dwarf shrub heathland above, where either less formal management is implemented or the grassland left to natural processes (as in nature conservation areas) it would be expected all three age classes would be present.

Regeneration Potential: This structural element is not defined in the JNCC monitoring guidance. Many species in this grazed grassland, particularly the grasses, spread and regenerate vegetatively (e.g., tillering, stolons, rhizomes) and are not necessarily reliant on the production of seed and seedling , and management programmes can be devised to promote these vegetative growth forms (Spedding, 1971).

Genetic Pool: Whilst no current JNCC guidance is given for this structural element, where it is proposed to establish native grasslands in reclamation schemes it is now expected that local sources are required. Until quite recently, seed in the UK has been typically sourced abroad or has been grown from horticultural stock or from seed collected elsewhere in the UK. Local harvesting from existing stands for reclamation schemes is possible, as described by Humphries (2012).

Indicators of Local Distribution: In the UK there are twenty one types of acid grassland communities (Rodwell, 1992). JNCC (2009b) identify five of these (NVC U2, U3, U4, U5 & U6) as being upland types. Like the woodland and dwarf shrub heathland, all five types of acid

17 Journal American Society of Mining and Reclamation, 2013 Volume 2, Issue 2 grassland have distinct regional and local characteristics. For example, NVC U4c Lathyrus montanus – Stachys betonica sub-community is only found in a few locations in the Derbyshire Dales in central England, here, the indicator species are the grasses: Oat Grass (Avenula pratensis), Crested Hair-grass (Koeleria macrantha), Quaking Oat-grass (Briza media) and Heath Grass (Danthonia decumbens).

Exotic / Alien and Weed Species: The JNCC guidelines are prescriptive as to the amount of alien and weedy species, woody species, and other types of grassland species for the grassland to qualify as acid grassland.

Discussion

The origin of this paper was a thought stimulating presentation given by Professor Jim Burger at the annual ASMR meeting at Tupelo in 2012. He considered the notion and application to mine site reclamation that ecosystem structure and function were intrinsically linked with the type and level of ecosystem recovery achieved (Bradshaw, 1987, Burger, 2012). The purpose of this paper is to explore this further and attempt to define a workable methodology whereby the successful restoration of the biotic component of important CBD (conventional or biological diversity) ecosystems in the UK might be determined. In considering, the possible application and value of the proposed JNCC derived CARGIE Model, there were a number of issues that might be asked by academics, practitioners, and regulators. Some of the more obvious ones are discussed below.

Does the CARGIE Model Meet CBD Standards? Of foremost importance, a key requisite for the acceptance of the CARGIE Model is whether it meets CBD expectations and standards. If not then the Model may not be accepted as a measure of success in the assessment of restoration schemes. As the Model is derived directly from the current and proposed government agency tool used for the monitoring and management of biodiversity reference ecosystems in the UK (JNCC, 1998), there is no reason to believe it would not be accepted (at least in principle) by the stakeholders. Hence, it is reasonable to believe it could be applied to both the design and assessment of mine reclamation as set out in this paper.

Ecosystem Structure May Not be Equitable to Function It is implicit in the proposed CARGIE Model that levels of ecosystem structure are equitable to levels in function. This is likely to be considered highly contentious amongst many ecologists (C. Zipper, pers. com.), although it is also the basis of the readily accepted Bradshaw derived

18 Journal American Society of Mining and Reclamation, 2013 Volume 2, Issue 2 model (Bradshaw, 1987). In this respect the JNCC Common Monitoring Standards (JNCC, 1998) stand out having identified the key structural biotic elements for the entire range of UK terrestrial ecosystems and implicitly assumes there is consummate functioning of the ecosystem as a result. The structural elements are at the vegetation community scale as originally suggested more than sixty years ago by Arthur Tansley (1949). The vegetation communities provide the habitat and food sources for the associated plant, animal, and microbe communities. For example, the decaying trees and dead wood were named as an essential component for woodland ecosystems providing habitat and substrate for saprophytic invertebrates, fungi, and bacteria (Jonsson and Stockland, 2012a). The JNCC approach reasonably assumes that the presence of dead wood is an indicator of their presence within the woodland or at least provides an opportunity for their occurrence.

The Approach Ignores the Belowground Components The CARGIE Model and the JNCC criteria focus on the aboveground structural characteristics and criteria. As a result they are both open to criticism that important belowground species’ rich biotic elements and essential functions such as decomposition and nutrient cycling are ignored (Bardgett et al., 2005; Wurst et al., 2012), given the importance of the soil as the supporting physical and biotic habitat. Whilst in this context the proffered approach is somewhat simplistic, it may be that for some ecosystems, the functioning of the belowground components could be manifest in the composition and condition of the aboveground litter layer, hence its incorporation into the soil and involvement in the soil-carbon and soil-nutrient transformation processes. This is demonstrated by the studies on the restoration of the Jarrah (Eucalyptus marginata) forest on bauxite mines (Grant et al., 2007).

It could be argued in defence of the JNCC approach that the aboveground vegetation communities are themselves an integration and expression of both the structure and functioning of the aerial environment (climate) and the soil environment (including the biotic components), thereby embracing decomposition and nutrient cycling processes in the soil. This notion is supported by a view that it is the plant roots and buried aboveground derived plant , and their associated bacteria, fungi, protists, and animals that are the overarching biotic components of soils (Bardgett and Wardle, 2010; Jonsson and Stokland, 2012a; Siitonen and Stokland, 2012). Different species of plants and therefore plant communities have their root and soil associations, some of which are known to have key roles in plant community development (Marx, 1991; Jose

19 Journal American Society of Mining and Reclamation, 2013 Volume 2, Issue 2 et al., 2006; Piotrowski et al., 2008). Some of the other biotic components, such as those involved in decomposition processes, may be essential for a fully functioning ecosystem, whereas others are not and simply reflect the array of diversification of living entities within the same habitat giving rise to notion of species redundancy in the functioning of ecosystems (Ritz, 2005; Thompson, 2010).

Given the current swell in research into soil diversity and function (Wall, 2012), this particular criticism of the Model (the balance between above- and belowground biotic relationships), merits further investigation and, if the Model is to be a valid representation, further refinement to the Model may be possible to encompass the belowground structural components.

What about the ?

Whilst the abiotic physical environment (climate, topography, soils, etc.) component of ecosystems has not been explicitly considered in the Model, it is acknowledged as being the most commonly considered factor determining the potential level of ecosystem type, development, and function on restored mine sites. Here, much research and monitoring effort has been put into defining these and the modification of the abiotic environment and the biotic response, and in particular growth ( responses). Interestingly, Jonsson and Stokland (2012a) refer to plants themselves as being the abiotic environment for a range of saproxlic species.

There are various methodologies whereby the potential of sites and soils might be determined for a range of agricultural, forestry, and natural ecosystems, for example, that set out by Humphries and McQuire (1994b). Such abiotic criteria can be used to predict the type and level of ecosystem achievable and the type of amendment required for specific ecosystems to be restored (the ecosystem being defined by NVC vegetation community type (Rodwell, 2006).

Rodwell in his NVC monographs defines the abiotic components for each of the community types and their derivatives. As set out above for the below ground components, it can be reasonably argued that the vegetation communities are themselves an integration and expression of both the biotic structure and the abiotic aerial (climate) and soil environments as illustrated by the following example. Festuca ovina – Carlina vulgaris calcareous grasslands (NVC CG1, Rodwell, 1992) occurs on excessively draining, base-rich and strongly alkaline (pH 6.4 – 8.1) oligotrophic rendziniform soils on calcareous bedrock. It is confined to areas with 800 to 1,000mm annual rainfall and low frequency of frost days. In contrast, Festuca ovina – Agrostis capillaris –

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Galium saxatile calcifugous grasslands (NVC U4) occurs on moderately draining, base poor moderately to strongly acidic (pH 4.0 – 5.5) oligotrophic shallow ranker soils over bedrock in areas with 800 to 1,600mm annual rainfall. Whilst the sub-community variants of the coastal CG1 vegetation type may be a result of geographic isolation, those of the more ubiquitous upland U4 type reflect gradients in winter and summer temperature extremes, rainfall, and nutrient levels with transition types of a mesotrophic Lolium perenne – Cynosurus cristatus grassland character on more typical brown soils (NVC MG6b, Rodwell, 1992). Given that they are reflecting both the aerial and the soil abiotic environments, and integrating climate-soil interactions, it is possible to predict the type and range represented by the vegetation community types. Hence, in characterising the vegetation community type, the CARGIE Model can be used with confidence in the integration of biotic and abiotic elements.

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Equally Applicable to Vegetation Development, Succession and Natural Colonisation? Because the JNCC derived, CARGIE Model is based on vegetation life cycles, it caters to community development from juvenile seedling stages through to mature and over-mature senescent stages, and the mixture of age classes to be expected in a restored ecosystem for a given set of land use and management circumstances. Examples of these are set out in Tables 1, 2 and 3. Where the CARGIE criteria have been reached, this will be the point that restoration of a particular ecosystem has been achieved because of vegetation and community development.

It might also be asked what is the Model’s use in the assessment of the success of natural colonisation and succession in restoration schemes? Whilst the definition of success here is dependent on the objectives and desired outcomes of a restoration scheme, in the UK context it is possible to define and compare with the target NVC vegetation communities for a given location, site, soil, and other circumstances. In doing so, a set of CARGIE criteria can be assembled against which an assessment can be made. Where vegetation development and further immigration leads to succession, these can be defined again in NVC terms and allocated CARGIE criteria for assessment of success. In these circumstances, a sequence of CARGIE criteria would be expected.

Where natural colonisation is being relied upon, as for vegetation development and succession, NVC types and CARGIE criteria can be set for appropriate outcomes. Success will largely be a function of their abundance, mobility, and their local presence. Whilst mobile species such as birds and flying invertebrates rapidly recolonize restored land (where there is suitable habitat), other species like some woodland plant species (which spread vegetatively) and some soil invertebrates typically spread very slowly, and may not recolonize areas for a very long period of time, if at all. This may have consequences where there are Indicators of Local Distributions for the achievement in all the CARGIE criteria.

Adaptive to Climate Change? The UK NVC spans a range of climatic conditions and the interactions with soils and other factors. Consequently, it is possible to redefine the likely vegetation communities and their sub- community types according to climate. In the CARGIE Model, the most likely changes over time are with the Canopy criteria (community characteristic main tree species), the Regeneration Potential (increase or decrease in fecundity), Indicators of Local Distribution, and Exotic/Alien and Weed Species.

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For example, with warmer and drier conditions at the lower margins of the Quercus petrea – Betula pubescens - Dicranium majus Oak Woodland (NVC W17, Rodwell, 1991a) a transition to the Quercus – Betula – Deschampsia flexuoas Oak Woodland (NVC W16) would be predicted. Probably little change in the Canopy, Age Class, Regeneration Potential, Genetic Pool and Exotics, and Aliens might be expected in this case. However, the Indicators of Local Distribution are likely to change with the invasion of Bracken and Bramble (Rubus fruticosa agg.) with the woodland assuming more of a NVC 16 character. This example is of a relatively insensitive kind, in contrast, the NVC CG1 grassland referred to above is on the other hand very sensitive to rainfall levels. As a possible outcome of future climate change in the UK, an increase in annual rainfall may lead to the invasion of more competitive species in this short and well drained open-turf community. This is likely to drive a change to the scrub community of Crataegus monogyna – Hedra helix – sub- community Brachypodium sylvaticum scrub (NVC W21c (Rodwell, 1991a)), comprising Wild Privet (Ligustrum vulgare), Bramble, Ivy (Hedra helix) the tussocky grass False Brome (Brachypodium sylvaticum). Hence, a JNCC based CARGIE Model can be prepared for both the current and the future predicted vegetation communities for design and assessment purposes.

Projected Time Scales for Ecosystem Restoration The CARGIE Model can be used to explore and assess the projected time scales for the restoration of ecosystem structural and function.

Taking woodland as an example, typically woodland reclamation starts with the planting of nursery grown trees and shrubs which in time grow and mature to saplings, mature, and seed bearing trees; then progress to decaying trees; and eventually become dead wood with each stage providing their functional entities. Whilst the development of the trees and shrubs in themselves provides for increase in structural complexity and graduation to a fully functioning ecosystem, it is the coincidence of several of the structural forms over time that together provide the increasing functional complexity associated with fully restored ecosystems (as illustrated by the notation in Table 4). What is clear is the attainment of at least three requisite structural elements will only occur sometime the first complete life cycle of the planted tree layer is completed or near to completion.

Table 4: Sequential development of ecosystem structural elements in a traditionally planted restoration scheme

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Tree Layer Traditional Restoration Scheme Woodland Development / Ecosystem Life Cycle Target Planted Stock Subsequent Woodland Stand Development from Planted Stock 1 S S Z M D F 2 Z S Z M D F 3 M S S Z M D F 4 D Z S Z M D F 5 F M S S Z M D F Key : S - seed / seedlings / nursery stock; Z – sapling; M - mature /seed bearing; D - decaying; and F - dead fallen trees

As might be expected (in the context of the life cycle dynamics of the biotic components of ecosystems), time is an important variable and probably the ultimate determinant of when ecosystems are actually restored. It is inherently longer in woodland systems where just nursery stock is provided (Table 5). This is inherently longer in woodland systems compared to dwarf shrub and grassland ecosystems where life cycles are shorter (Table 5).

Table 5 demonstrates clearly the difference in timescales that the attainment of the required ecosystem structural elements might be achieved (i.e., all the life cycle stages at the same time). In the case of grassland communities this might be achieved relatively quickly and within 15 years (where longer lived semi-woody components are present such as the rhizomatous Potentilla erecta in the upland Festuca ovina – Agrostis capillaris – Galium saxatile acid grasslands (NVC U4, Rodwell, 1992)) or sooner where woody herbaceous plant species are absent. For the dwarf shrub communities the period is longer still and in the order of 30-50 years.

In contrast, the Birch and Oak components of woodland may be as much as 150-200 and 250- 350 years respectively, with Birch dominated woodland potentially completing two complete life cycles within the first for Oak dominated woodland.

Table 5: Comparative schematic temporal development of structural elements in woodland, dwarf shrub and grassland ecosystems (bold symbols indicate when all age classes are present) Tree Layer Traditional Restoration Scheme Development / Life Cycle

YEARS Birch Woodland Oak Woodland Dwarf shrub Upland (Heather) Grassland heathland

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0-5 S S S S Z M B 5-10 Z S Z B S S Z M B D 10-15 Z Z Z B S S Z M B D F 15-20 M Z M B S D 20-30 B S Z D B S M 30-50 B S M F D B S M 50-70 D Z B S 70-80 F D M B S Z 80-100 F B S B S Z 100-120 B S Z B S Z M 120-150 D M Z M Z B S 150-200 F D B Z B S D Z M B S 200-250 F D B Z B S D Z M B S 250-350 F D B Z B S F D M B S Z Key : Key : Key : S - seed / seedlings / nursery stock S - pioneer S - seed/ seedlings Z - sapling Z - building Z - tillering etc M - mature M - mature M - mature & B - seed bearing B - seed bearing B - seed bearing) D - decaying D - degenerate D - degenerate F - dead fallen trees F - dead F - dead

Applied at What Scale ? The JNCC Common Standards for Monitoring (JNCC, 1998) is designed to be applied at the vegetation community scale within typical landscape settings of, for example, wooded valleys, and heather moorlands. Minimum qualifying areas for small isolated parcels of land are set out for descriptive and monitoring purposes; generic vegetation types and sample sizes are prescribed and can be applied to mine restoration schemes. Where CARGIE criteria are quantified, these units are to be applied on a pro rata basis.

Implications for Restoration Practices An outcome of the CARGIE Model is an understanding of the importance of life cycle completion and renewal, and its key role in determining ecosystem restoration of the natural vegetation communities. Hence, it would be expected to find a mixture of appropriate age classes in restored communities if they and the ecosystem were to be judged self-sustaining and the scheme a success. Restoration schemes are typically simplistic in that the component species are planted or sown at prescribed densities and then left to mature or are managed in some manner with the result it can be decades or centuries before the semblance of mixed aged communities are established. The implications are that certain parts of the ecosystem structure and function may not be re-established in some types of vegetation community for a very long period of time and

25 Journal American Society of Mining and Reclamation, 2013 Volume 2, Issue 2 long after any prescribed aftercare period when further inputs and management are unlikely. Given this, it is important for practitioners to be aware and take whatever actions they can to provide for the age class related structural elements. In the case of woodlands the key elements being new cohorts of recruits and dead wood.

Whilst there is an opportunity to prime the new woodlands by introducing dead wood and ‘short-circuit’ this time limiting process for ecosystem restoration by thinning programs at the sapling and early mature stage and leaving the cut-wood (rather than its removal as in commercial woodlands), this option is likely to be much less beneficial (as it relies on colonisation by dead wood saproxylic species from outside) than the introduction of dead wood from mature woodland with its in situ dead wood species (Stokland, 2012; Jonsson and Stokland, 2012a and 2012b).

Where woodland has been cleared as part of the mine development, there is an opportunity to introduce mature and over-mature felled timber as complete trees, root-plates, and branches with their associated animal and microbe communities into the planting scheme thereby short-circuiting the long process of dead wood production. This requires a change in general practice where often woodland is being cleared to make way for mining. Here, the dead wood and litter layers should be considered as valuable restoration resources and where possible retained and reintroduced as good practice.

Concluding Comments

The original notion behind this paper was that some dimension (yet to be defined) was probably the key to practical ecosystem reclamation on mine sites. What has come out of the debate, firstly, and not unsurprisingly, time (because of the life cycle dynamics of the biotic components of ecosystems) is probably the key dimensional scale and the ultimate determinant of the achievement of ecosystem reclamation, and challenges our own perceptions of restoration achievement and restorability. Secondly, vegetation communities are a practical and justifiable scale to consider ecosystem restoration for mine sites. To this end, the CARGIE Model could enable better design and evaluation of restored ecosystems and their services, before and after surface mining, and enable the mining industry in the UK to meet the challenges posed by CBD and the new and emerging legislation and policies.

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At the outset, the aim of this paper was simply explorative. The CARGIE methodology suggested is just an idea and is open to further examination and development if it is deemed to have merit. If not, maybe an outcome of this paper is that stimulates others to suggest alternatives.

If the CARGIE Model is to have a wide application and to be generally useful, the next steps could be to determine:

1 If the qualifying criteria can be identified and applied to other Biomes.

2 If it is justifiable to assume the soil ecosystems are integrated within the model, and if not what above- or belowground-based criteria should be added to the CARGIE model.

3 The outcomes of applying the Model to restored mine sites.

In these and any other respect, the author welcomes comments, other’s experiences, and the exchange of ideas.

Acknowledgements

I would like to thank the anonymous Reviewers and Carl Zipper (Virginia Tech, Blacksburg) for their helpful comments on the original manuscript.

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