British Columbia Mine Reclamation Symposium

Assessing the level of difficulty of vegetation establishment on reclaimed sites Cranston, B. H.; Waterman, L. P. 2015

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Mine Closure 2015 – A.B. Fourie, M. Tibbett, L. Sawatsky and D. van Zyl (eds) © 2015 InfoMine Inc., Canada, ISBN 978-0-9917905-9-3 Mine Closure 2015, Vancouver, Canada 1  B.H. Cranston  Paragon Soil and Environmental Consulting Inc., Canada L.P. Waterman  Paragon Soil and Environmental Consulting Inc., Canada   Regulatory approvals for oil sands mining in Alberta, Canada, require that disturbed land be reclaimed to a self-sustaining, locally common boreal forest ecosystem; biodiversity is also a key stakeholder concern. Not all ecosites are readily reclaimed, yet conceptual reclamation plans often make assumptions that discount this challenge. To this end, we have developed a ranking system that uses measurable values to determine the level of difficulty to establish target vegetation on upland and transitional reclaimed sites. The ecosite phase reclamation targets of the Athabasca Oil Sands (Alberta, Canada) were used as a model system.  Six metrics were used to determine the relative difficulty to reclaim each upland and transitional ecosite phase: time required for target vegetation establishment, level of management required, difficulty associated with achieving the requisite edaphic (soil moisture and nutrients) regime, sensitivity to changing soil chemistry, utility of direct soil placement and erosion potential. Each metric was given a weighted value (1 through 4) according to its overall influence on the difficulty of reclaiming each ecosite phase. The weighted values of metrics deemed difficult, neutral and easy for a particular ecosite phase were multiplied by −1, 0 and +1, respectively. The values for all six metrics were then summed for each ecosite phase, yielding an overall value for the difficulty to reclaim each phase. Values below −2 were deemed to be difficult, −2 to +2 were deemed neutral and values exceeding +2 were deemed not difficult (“easy”) relative to the innate challenges of reclaiming anything on the scale of mineable oil sand leases.  This method of quantifying the level of difficulty in establishing target vegetation communities can be applied to any post-disturbance reclamation project. Its adoption would have broad-scale implications on activities from reclamation planning to revegetation practices and monitoring techniques. According to the Environmental Protection and Enhancement Act (EPEA) of Alberta, Canada, oil sands companies are required to submit a long-term, conceptual planning document (life of mine closure plan) that extends to the end of mine life. This plan outlines the technical measures and planning programs to be undertaken for the decommissioning, remediation and reclamation of a mine and plant site, with the ultimate goal of reclamation certification and return of land to the Crown (Pickard et al., 2013). Each operator must outline the extent (number of hectares) of reclamation planned for each year of project duration, allowing for identification of any mismatches between early and late reclamation. Ensuring that all site types, landforms, soils and regions are included in early reclamation increases learning and allows processes and practices to be adapted for maximum efficiency in later years. Adaptive management allows information to be fed back into the planning and design process so that future reclaimed areas will meet the intended objectives. Years in which more reclamation is planned than can practically be completed may also be identified.   While life of mine planning may identify pitfalls with respect to reclamation extent, it does not specifically account for the relative difficulty and required effort to re-establish various vegetation communities. To this end, we have developed a ranking system that uses measurable values to determine the level of difficulty of establishing target vegetation on reclaimed sites, using the ecosite phase reclamation targets of the Athabasca Oil Sands (Alberta, Canada) as a model system. As of 2013, only ~7% of the total area disturbed Assessing the level of difficulty of vegetation establishment on reclaimed sites B.H. Cranston and L.P. Waterman  2 Mine Closure 2015, Vancouver, Canada within the Athabasca Oil Sands has been reclaimed (Pickard et al. 2013). Approximately 32% is expected to be reclaimed by 2035, but the majority of reclamation will occur after 2035 (Pickard et al., 2013).  The ecosite phase targets of Athabasca Oil Sands reclamation were used to demonstrate the application of the difficulty matrix. Ecosites and their associated phases are mappable units dependent on the edaphic conditions (soil moisture and nutrient levels) at the site, and are not tied directly to landforms or vegetation communities (Beckingham and Archibald, 1996). For the ecosites under consideration in this paper, moisture regimes range from xeric to hygric, with very poor to very rich nutrient regimes. Each ecosite phase is described briefly in Table 1, and examples are depicted in Figure 1.  Ecosite Moisture regime Nutrient regime Key overstory species Key understory species a1 Subxeric–xeric Poor Jack pine Blueberry, bearberry, bog cranberry, cladina b1 Submesic–subxeric Poor Jack pine, aspen Bog cranberry, blueberry, green alder, bearberry, Labrador tea b2 Submesic–subxeric Poor Aspen, white birch Bearberry, Labrador tea, blueberry, green alder b3 Submesic–subxeric Poor Aspen, white spruce Blueberry, bearberry, bog cranberry, prickly rose b4 Submesic–subxeric Poor White spruce, jack pine Bearberry, blueberry, green alder, white spruce, bog cranberry c1 Mesic–submesic Poor Jack pine, black spruce Labrador tea, bog cranberry, black spruce, blueberry d1 Mesic Medium Aspen, balsam poplar Prickly rose, low-bush cranberry, Canada buffaloberry, twin-flower d2 Mesic Medium Aspen, white spruce Low-bush cranberry, prickly rose, twin-flower d3 Mesic–subhygric Medium White spruce, balsam fir Twin-flower, low-bush cranberry, balsam fir, prickly rose e1 Subhygric Rich Aspen, balsam poplar Prickly rose, dogwood, low-bush cranberry, bracted honeysuckle e2 Subhygric Rich White spruce, aspen Dogwood, low-bush cranberry, prickly rose, bracted honeysuckle f2 Hygric Rich White spruce, white birch Low-bush cranberry, willow, prickly rose, dogwood, horsetail f3 Hygric Rich White spruce Prickly rose, low-bush cranberry, currant, horsetail, marsh reed grass g1 Subhygric Poor Black spruce, jack pine Labrador tea, black spruce, bog cranberry, blueberry h1 Hygric Medium–Rich White spruce, black spruce Labrador tea, bog cranberry, willow, prickly rose, twin-flower, horsetail Miscellaneous Mine Closure 2015, Vancouver, Canada 3  To date there has been limited consideration of the practicability of reclaiming a comparatively full spectrum of upland and transitional ecosites. The research and technology transfer required to reclaim upland areas is relatively advanced compared to that for wetlands. Nonetheless, field experience and an examination of Assessing the level of difficulty of vegetation establishment on reclaimed sites B.H. Cranston and L.P. Waterman  4 Mine Closure 2015, Vancouver, Canada some industry closure plans submitted by area operators suggest that closer examination of upland reclamation challenges is warranted.  Six metrics were used to determine the relative difficulty to reclaim each upland and transitional ecosite phase:   the time required for a particular ecosite phase to establish;  the level of management required for ecosite phase vegetation to establish and be maintained;  the difficulty associated with achieving the edaphic (soil moisture and nutrients) regime;  the sensitivity of each ecosite phase to changing soil chemistry;  the utility of direct soil placement; and  the erosion potential. Each metric was given a weighted value according to its overall influence on the difficulty of reclaiming each ecosite phase. The weighted values of metrics deemed difficult, neutral and easy for a particular ecosite phase were multiplied by −1, 0 and +1, respectively. The values for all six metrics were then summed for each ecosite phase, yielding an overall value for the difficulty to reclaim each phase. Values below −2 were deemed to be difficult, −2 to +2 were deemed neutral, and values exceeding +2 were deemed not difficult relative to the innate challenges of reclaiming anything on the scale of mineable oil sand leases. The six metrics are described below. The time required for a particular ecosite phase to become established is partly dependent on the management level needed. The longer it takes for a vegetation community to develop, the more erosion and invasive species mitigation will be necessary.  In the past, vegetation communities were generally assumed to be established once they reached a “stable state.” However, a new understanding of community succession following disturbance suggests that succession rarely leads to a stable, unchanging configuration. This is because unpredictable changes in weather, hydrology, seasonal changes of light and temperature, and internal mechanisms in populations continuously affect the structure and function of natural systems (Connel and Slatyer, 1977; Dokulil et al., 2006). In a review by Connel and Slatyer (1977) no examples of a community of sexually reproducing individuals were found in which the average species composition had reached steady-state equilibrium. On this lack of evidence, they concluded that, in general, succession never stops. Therefore, achieving a stable state is a poor metric for community establishment. To determine the time required for each ecosite phase to become established, all phases were considered to be successional.  Two factors were considered when determining time to establish: (1) when are the successional trajectories initiated that will likely lead to the specified community configurations, and (2) at what time in succession is that configuration typically reached? Most seedlings will have established within 10 years following the initial disturbance, but it is the changing dominance of species within the community that will determine which ecosite phase has become established at any particular point in time. Individual growth rates for species characteristic of target ecosite phases are therefore a critical factor for this metric.  The individual growth rates of target species for each ecosite phase vary significantly; established communities may not perfectly represent target species assemblages. By taking this variation into account, it is possible to rank the ecosite phases relative to one another. Some ecosite phases (a1, b1–2, c1) are characterised by an understory dominated or co-dominated by lichen species. These lichens are slow to disperse and grow, sometimes taking 50+ years to establish. Wet-rich ecosite phases (e, f, h1), by comparison, with a predominantly fast-growing, herbaceous understory, should become established relatively quickly. To quantify these differences, the site index at 50 years is supplied for each ecosite phase. Miscellaneous Mine Closure 2015, Vancouver, Canada 5 There were several considerations behind the determination of management level for each ecosite phase. Mainly, the amount of erosion mitigation required, control of undesirable plant invasion, and fertilisation were evaluated. Weed management requirements were anticipated for all ecosites and were therefore not directly accounted for in the matrix. The primary methods of erosion control include proactive practices such as rough soil mounding, coarse woody debris (CWD) placement and the planting of nurse crops (Burger et al., 2009; Paquin and Brinker, 2011; Naeth and Brown, 2014). Nurse crops are not suggested for ecosite phases that have low productivity and target vegetation that is slow to establish, such as a1. Nurse crops can outcompete target vegetation, preventing it from establishing in such cases (Padilla and Pugnaire, 2006). Those ecosites that are unable to support nurse crops are therefore prone to invasion from weeds and non-native and non-target plant species, likely requiring moderate to aggressive management. In some cases, even target species (e.g. aspen) may need to be managed to ensure that they do not begin to dominate the site. This is not to say that initial ecosite targets will never be adjusted to allow for emergence of unplanned yet desirable species, but if biodiversity somewhat comparable to pre-development conditions is sought, some areas will require management to achieve the original targets. Finally, the need for fertilisation was evaluated. Fertilisation should only be used if necessary; fertiliser type, timing of application and the amount applied should be carefully considered (Alberta Environment and Water, 2012). Applying fertiliser directly after soil placement or before planting can encourage the growth of weeds and other herbaceous plants to the detriment of slow-growing target plants, which can be easily outcompeted (Preston et al., 1990). Likewise, excess fertilisers not taken up by the targeted plants tend to encourage the growth of herbaceous competitors (Preston et al., 1990). Fertilisation programs should rather be based on timely soil and foliar analyses. Along with establishing the edaphic regime, management level has the highest weighting relative to the other metrics. The amount of management required to establish and maintain ecosite vegetation communities is directly related to the difficulty of reclaiming each phase, and thus the cost. Along with vegetation, the edaphic regime is a key factor determining ecosite phase classification. For this reason, it has been assigned the highest weighting value of 4, an equivalent weighting to management level.  Some edaphic conditions are known to be difficult to achieve, particularly those of “extreme” upland ecosite phases, such as the dry-poor (a1), and wet-rich (e, f) phases. The c1 and g1 ecosite phases are also challenging to recreate; as soil moisture levels rise, it is difficult to maintain the poor to very poor nutrient levels required. This explains why c1 and g1 ecosites commonly occur in relatively narrow bands in the transition between upland and lowland, often adjacent to each other. Oil sand mine closure plans commonly target substantially larger swaths of c1 and g1 ecosites than may be feasible to achieve. Some plant species (i.e. Labrador Tea and bog cranberry) are tolerant of acidic conditions and can be indictors of plant communities that are relatively tolerant to changes in soil chemistry. Moreover, ecosite phases that have very specific, difficult-to-achieve edaphic requirements are predicted to be intolerant to changes in soil chemistry, much as specialist species are intolerant to change (Dukes and Mooney, 1999). No ecosite phase was rated as positive for this metric (very tolerant).  This metric was assigned a low weighting, primarily because it is also captured to some degree in the “difficulty to achieve edaphic regime” metric, which was assigned a higher weighting.  Direct soil placement is widely recognised as a useful tool for reclamation (Bell, 2001), not only because of the cost-savings associated with moving the soil only once (relative to moving it to stockpiles and placing it Assessing the level of difficulty of vegetation establishment on reclaimed sites B.H. Cranston and L.P. Waterman  6 Mine Closure 2015, Vancouver, Canada at a later date), but also because it encourages more rapid establishment of target vegetation — assuming the ecosite at the source is aligned with that of the target location. Avoiding lengthy stockpiling of soils allows viable source seed and other propagules (root/rhizome segments, etc.) to be retained in the soils (Bell, 2001). Once placed, these seeds/propagules can germinate and root, allowing target vegetation to establish as quickly as possible after soil placement. This natural revegetation can then be supplemented by planting as needed; however, planting requirements will likely be reduced, providing further savings.  Direct soil placement will be particularly effective for ecosite phases with low productivity vegetation, which is slow to establish and has low dispersive ability. No ecosite phase was predicted to be negatively impacted by direct soil placement practices. This metric was assigned a moderate weighting value of 2. Erosion potential includes both wind and water erosion. Wind erosion is a particular issue for dry ecosite phases, those in which vegetation is slow to establish and those in which nurse crop planting is not recommended. For these phases, soil is not stabilised and can easily be picked up by the wind.  Water erosion can be a problem for any ecosite, but is most severe before planting. Establishing a nurse crop has been proven to be an effective method of erosion control and soil stabilisation for those ecosites with highly productive, herbaceous vegetation (Burger et al., 2009). However, nurse crops have the potential to attract wildlife, and thus their use must be carefully considered when near active mine areas. Other methods of erosion control proven effective include rough soil mounding and CWD placement (Paquin and Brinker, 2011; Naeth and Brown, 2014). Both of these methods involve the creation of microtopographic variability, resulting in microclimatic pockets of favourable growing conditions.  The erosion potential metric was given a moderate weighting because it is also captured, to a degree, in the management level metric above.  The rating system presented is not intended to suggest that reclamation of any ecosite is easy; rather, the system provides a relative classification. Careful management of reclamation resources and thoughtful planning will always be required, regardless of the estimated level of difficulty. The difficulty matrix is presented in Figure 2.    Ecosite operational constraints   Time to establish  (site index [m]) Management level Difficulty to achieve edaphic regime Sensitivity to changing chemistry Utility of direct soil placement Erosion potential Difficulty to reclaim*   Weight 1 4 4 1 2 3 a1 Lichen, jack pine 50+ years  Site index: Pj = 13.4 ± 0.3  High: CWD for erosion, no fertilisation, competition must be managed  High: xeric and nutrient poor Neutral: tolerant of acidity, tolerance to alkalinity unknown High: introduces lichens, mosses, ericoid mycorrhizae High: very slow establishment of ground cover  −10 Strategy: Establish on coarse, rapidly draining soil that is relatively level. Typically found on topographic high points, but in reclaimed situations erosion risk necessitates more level area targets. Invasion and competition are high because of slow understory establishment. Any fertilisation will cause target species to be outcompeted (mosses/lichens in particular). Instead of vegetative erosion control, CWD and soil mounding is suggested. Lichens and dwarf shrubs are slow to establish. Competition from aspen will need to be controlled. Miscellaneous Mine Closure 2015, Vancouver, Canada 7   Ecosite operational constraints   Time to establish  (site index [m]) Management level Difficulty to achieve edaphic regime Sensitivity to changing chemistry Utility of direct soil placement Erosion potential Difficulty to reclaim*   Weight 1 4 4 1 2 3 b1 Blueberry, jack pine, aspen ~35 years Site index: Pj = 14.3 ± 0.5 Aw = 15.8 ± 0.5  Neutral: no fertiliser, use CWD for erosion, less competition management than in a  Low: develop a range of moisture and nutrient regimes Neutral: tolerant of some acidity, tolerance to alkalinity unknown High: introduces lichens, mosses, ericoid mycorrhizae High: slow establishment of ground cover 2 Strategy: Establish on coarse, well-draining soil. Invasion and competition are strong, but less so than for a1. Fertilisation will promote the establishment of herbaceous competitors, outcompeting target groundcover species. Lichens and dwarf shrubs are slow to establish. Special care and additional monitoring are suggested if using alkaline soils. b2 Blueberry, aspen (white birch) ~35 years Site index: Aw = 15.8 ± 0.6 Bw = 17.5 ± 0.7  Neutral: no fertiliser, use CWD for erosion, less competition management than in a  Low: develops on a range of moisture and nutrient regimes Neutral: tolerant of some acidity, tolerance to alkalinity unknown High: introduces lichens, mosses, ericoid mycorrhizae High: slow establishment of ground cover 2 Strategy: Establish on coarse, well-draining soil. Invasion and competition are strong, but less so than for a1. Fertilisation will promote the establishment of herbaceous competitors, outcompeting target groundcover species. Lichens and dwarf shrubs are slow to establish. Special care and additional monitoring are suggested if using alkaline soils.       b3 Blueberry, aspen, white spruce ~30 years Site Index: Aw = 15.8 ± 0.7 Sw = 17.5 ± 0.7  Neutral: no fertiliser, use CWD for erosion, less competition management than in a  Low: develops on a range of moisture and nutrient regimes Neutral: tolerant of some acidity, tolerance to alkalinity unknown High: introduces lichens, mosses, ericoid mycorrhizae High: slow establishment of ground cover 3 Strategy: Establish on coarse, fairly well-draining soil, moisture trending towards submesic–mesic. Vegetation invasion and competition are strong, but less so than for a1. Fertilisation will promote the establishment of herbaceous competitors, outcompeting target groundcover species. Lichens and dwarf shrubs are slow to establish. Special care and additional monitoring are suggested if using alkaline soils. b4 Blueberry, white spruce,  jack Pine ~30 years Neutral: no fertiliser, use CWD for Low: can trend toward d Neutral: tolerant of some High: introduces lichens, High: slow establishment 3 Assessing the level of difficulty of vegetation establishment on reclaimed sites B.H. Cranston and L.P. Waterman  8 Mine Closure 2015, Vancouver, Canada   Ecosite operational constraints   Time to establish  (site index [m]) Management level Difficulty to achieve edaphic regime Sensitivity to changing chemistry Utility of direct soil placement Erosion potential Difficulty to reclaim*   Weight 1 4 4 1 2 3 Site index: Sw = 17.5 ± 0.7 Pj = 14.3 ± 0.5 erosion, less competition management than in a  when moisture conditions permit acidity, tolerance to alkalinity unknown mosses, ericoid mycorrhizae of ground cover Strategy: Establish on coarse, fairly well-draining soil, moisture trending towards mesic. Invasion and competition are strong, but less so than for a1. Fertilisation will promote the establishment of herbaceous competitors, outcompeting target groundcover species. Lichens and dwarf shrubs are slow to establish. Competition from aspen will need to be controlled. Special care and additional monitoring are suggested if using alkaline soils. c1 Labrador tea,  jack pine, black spruce ~30 years  Site index: Pj = 14.3 ± 0.4 Sb = 11.5 ± 0.6 Neutral: no fertiliser, use CWD for erosion, less competition management than in a  High: mesic moisture with low nutrients, specific soil types High: Sensitive to changes in soil conditions Neutral: introduces native propagules, less important than for a/b High: slow establishment of ground cover −8 Strategy: Requires very specific edaphic regimes and is difficult to reclaim. Established on medium-fine soils with poor nutrient conditions. Fertilisation will alter the edaphic conditions and push the vegetation towards d. Soil mounding and CWD are suggested as alternative erosion control measures. More likely to occur as unplanned inclusions.          d1 Low-bush cranberry, aspen ~30 years  Site index: Aw = 18.2 ± 0.2 Pb = 17.3 ± 0.6  Low: fertiliser ok once established, competition management not required Low: mesic moisture and medium-to-rich nutrients Neutral: can tolerate a range of conditions (submesic–subhygric, poor–rich) Neutral: introduces native propagules, less important than for a/b Neutral: ground cover quicker to establish, more herbaceous 8 Strategy: Can establish on a range of soil types (medium-to-fine texture, or peat-mineral mix) and edaphic conditions. Moderately productive. Fertiliser can be added once woody species have established. Soil mounding and CWD can be employed as additional erosion control methods. d2 Low-bush cranberry, aspen,  white spruce ~30 years  Site index: Aw = 18.2 ± 0.2 Low: fertiliser ok once established, competition management not required Low: mesic moisture and medium-to-rich nutrients Neutral: can tolerate a range of conditions (submesic–Neutral: introduces native propagules, less Neutral: ground cover quicker to establish, more herbaceous 8 Miscellaneous Mine Closure 2015, Vancouver, Canada 9   Ecosite operational constraints   Time to establish  (site index [m]) Management level Difficulty to achieve edaphic regime Sensitivity to changing chemistry Utility of direct soil placement Erosion potential Difficulty to reclaim*   Weight 1 4 4 1 2 3 Sw = 16.8 ± 0.2 subhygric, poor–rich) important than for a/b Strategy: Can establish on a range of soil types (medium-to-fine texture, or peat-mineral mix) and edaphic conditions. Moderately productive. Fertiliser can be added once woody species have established. Soil mounding and CWD can be employed as additional erosion control methods. d3 Low-bush cranberry,  white spruce ~30 years Site index: Sw = 16.8 ± 0.2 Fb = 14 ± 1.1 Low: fertiliser ok once established, competition management not required Low: mesic moisture and medium-to-rich nutrients Neutral: can tolerate a range of conditions (submesic–subhygric, poor–rich) Neutral: introduces native propagules, less important than for a/b Neutral: ground cover quicker to establish, more herbaceous 8 Strategy: Can establish on a range of soil types (medium-to-fine texture, or peat-mineral mix) and edaphic conditions. Moderately productive. Fertiliser can be added once woody species have established. Soil mounding and CWD can be employed as additional erosion control methods.            e1 Dogwood balsam, poplar, aspen ~25 years  Site index:  Aw = 21.4 ± 0.4 Pb = 19.7 ± 0.6 High: may require fertilisation program to obtain edaphic regime High: specific, challenging soil moisture conditions (subhygric, rich) Sensitive to changes in soil conditions Neutral: introduces native propagules, less important than for a/b Low: grasses and forbs characteristic, shrubs quick to establish −5 Strategy: Can only establish under very specific edaphic conditions. Requires subhygric soils rich in nutrients. Understory is competitive and quick to establish. A nurse cover can be used for erosion control if necessary. Soil mounding and CWD are also suggested for erosion control. This ecosite prefers low topographic positions with imperfectly drained soils. e2 Dogwood, balsam, poplar,  white spruce ~25 years Site index: Sw = 17.8 ± High: may require fertilisation program to High: specific, challenging soil Sensitive to changes in soil conditions Neutral: introduces native propagules, Low: grasses and forbs characteristic, −5 Assessing the level of difficulty of vegetation establishment on reclaimed sites B.H. Cranston and L.P. Waterman  10 Mine Closure 2015, Vancouver, Canada   Ecosite operational constraints   Time to establish  (site index [m]) Management level Difficulty to achieve edaphic regime Sensitivity to changing chemistry Utility of direct soil placement Erosion potential Difficulty to reclaim*   Weight 1 4 4 1 2 3 0.3 Aw = 21.4 ± 0.4 obtain edaphic regime moisture conditions (subhygric, rich) less important than for a/b shrubs quick to establish Strategy: Can only establish under very specific edaphic conditions. Requires subhygric soils rich in nutrients. Understory is competitive and quick to establish. A nurse cover crop can be used for erosion control if necessary. Soil mounding and CWD are also suggested for erosion control. This ecosite prefers low topographic positions with imperfectly drained soils. f2 Horsetail, balsam, poplar, white spruce ~25 years Site index: Pb = 17.8 ± 1.8 Sw = 16.4 ± 0.3 High: may require fertilisation program to obtain edaphic regime High: specific, challenging soil moisture conditions (subhygric, rich) Sensitive to changes in soil conditions Neutral: introduces native propagules, less important than for a/b Low: wet soils, blanket of horsetails and herbaceous cover −5 Strategy: Flooding and seepage enhances nutrient supply in f ecosites. Additional fertilisation may be required. Once established, horsetails will provide some erosion control. CWD is also suggested          f3 Horsetail, white spruce ~25 years Site index: Sw = 16.4 ± 0.3 High: may require fertilisation program to obtain edaphic regime High: specific, challenging soil moisture conditions (subhygric, rich) Sensitive to changes in soil conditions Neutral: introduces native propagules, less important than for a/b Low: wet soils, blanket of horsetails and herbaceous cover −5 Strategy: Flooding and seepage enhances nutrient supply in f ecosites. Additional fertilisation may be required. Once established, horsetails will provide some erosion control. CWD is also suggested g1 Labrador tea, subhygric black spruce, jack pine ~35 years  Site index: Sb = 9.9 ± 0.7 Pj = 11.7 ± 0.4 Neutral: no fertiliser, use CWD for erosion, less competition than in a, c  High: specific, challenging soil conditions (subhygric, poor) Sensitive to changes in soil conditions High: introduces native propagules Neutral: few forbs and grasses, wet soil reduces erosion potential −4 Miscellaneous Mine Closure 2015, Vancouver, Canada 11   Ecosite operational constraints   Time to establish  (site index [m]) Management level Difficulty to achieve edaphic regime Sensitivity to changing chemistry Utility of direct soil placement Erosion potential Difficulty to reclaim*   Weight 1 4 4 1 2 3 Strategy: Difficult to reproduce because of the specific soil types (finer textured, poorly drained) required. High risk of site modification if operations are conducted on unfrozen soil because of the high soil water content. Operations should be limited to the winter season. CWD and mounding can be used to deter vehicle and equipment traffic. h1 Labrador tea, horsetail, white spruce, black spruce ~30 years Site index: Sw = 12.9 ± 1.0 Sb = 9.5 ± 0.7 Neutral: may require fertiliser program, erosion control less important Neutral: moisture regime easier to recreate than g1 Neutral: vegetation tolerant to some acidity Neutral: introduces native propagules, less important than for a/b Neutral: blanket of horsetails, shrubs slower to establish 0  Strategy: Limited to topographic depressions with finer, poorly drained soils. Vegetation is more difficult to recreate than in g1. *less than −2 = high; −2 to +2 = neutral; more than +2 = low This method of quantifying the level of difficulty of establishing target vegetation communities can be applied to any post-disturbance reclamation project. Its implementation may have broad-scale implications for activities from reclamation planning to revegetation practices and the monitoring techniques required. Using the matrix, we have identified trends in the extent (ha) of difficult ecosite phase revegetation over the course of 50 years of planned reclamation at an oil sands project. A distinct peak of “difficult” revegetation activities was identified during the final years of reclamation and monitoring. These activities can now be rescheduled when practicable to take full advantage of monitoring and adaptive management during earlier stages of reclamation. Research can be adjusted as needed to focus on developing successful conditions for reclaiming the more challenging ecosites. Moreover, when applied to planned or placed soil prescriptions, specific limitations to vegetation establishment may be identified and potentially mediated.  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(1977) Mechanisms of succession in natural communities and their role in community stability and organization, The American Naturalist, Vol. 11, pp. 1119–1144. Dokulil M.T., Donabaum, K. and Pall, K. (2006) Alternative stable states in floodplain ecosystems, Ecohydrology and Hydrobiology, Vol. 6, pp. 37–42. Assessing the level of difficulty of vegetation establishment on reclaimed sites B.H. Cranston and L.P. Waterman  12 Mine Closure 2015, Vancouver, Canada Dukes, J.S. and Mooney, H.A. (1999) Does global change increase the success of biological invaders? Trends in Ecology & Evolution, Vol. 14, pp. 135–139.  Naeth, M.A. and Brown, R.L. (2014) Woody debris amendment enhances reclamation after oil sands mining in Alberta, Canada, Restoration Ecology, Vol. 22, pp. 40–48. Padilla, F.M. and Pugnaire, F.I. (2006) The role of nurse plants in the restoration of degraded environments, Frontiers in Ecology and the Environment, Vol. 4, pp. 196–202. Paquin, L.D. and Brinker, C. (2011) Soil salvage and placement: Breaking new ground at Teck’s Cheviot open pit coal mine. In Proceedings of the 2011 Mine Closure Conference, Lake Louise, AB, September 18-21, 2011.  Pickard, D., Hall, A., Murray, C., Frid, L., Schwarz, C. and Ochoski, N. (2013) Long-term plot network: Effectiveness monitoring program, prepared for the Plot Network Task Group, Terrestrial Subgroup, Reclamation Working Group, Cumulative Environmental Management Association (CEMA), Fort McMurray, Canada.  Preston, C.D., Marshall, V.G., McCullough, K. and Mead, D.J. (1990) Fate of 15N-labelled fertilizer applied on snow at two forest sites in British Columbia, Canadian Journal of Forest Research, Vol. 20, pp. 1583–1592.  

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