We address the question: under which circumstances can we rely upon spontaneous succession and when are technical measures more effective in restoration programs? To answer this question, the position of a disturbed site along the productivity–stress gradient was considered. The probability of attaining a target stage by spontaneous succession decreases toward both ends of the productivity–stress gradient, whereas the acceptance of technical measures generally increases. In correspondence with that, the monetary cost of restoration increases toward the ends of the gradient. Therefore, spontaneous succession is advocated especially if environmental site conditions are not very extreme.

To close this book, let us reiterate the goal of the book and ponder what we have achieved. As stated in the introduction, the aim of control loops is to maintain processes at the desired operating conditions, safely and efficiently. A poorly performing control loop can result in disrupted process operations, degraded product quality, higher material or energy consumption, and thus decreased plant profitability. Therefore, control loops have been increasingly recognised as important capital assets that should be routinely monitored and maintained. The performance of the controllers, as well as of the other loop components, should thus be improved continuously, ensuring products of consistently high quality. To achieve this goal, each component of the control loops should be monitored. The components of control loops include the actuator, sensor, controller and process. Each component is subject to possible faults or less-than-expected performance. Process and control monitoring has been a topic of active research over the last two decades. Actuator-fault detection along with sensor-fault detection has also been studied extensively in the faultdetection research community. The most important actuator in process industries is the control valve, and it has surprisingly received little attention until recently.

The objective of this work was to select indigenous vegetal species for restoration programs aiming at the regeneration of ombrophilous dense forest. Thirty-five spoil piles located in the county of Sideropolis, Santa Catarina, that received overburden disposal for 39 years (1950–1989) were selected for study because they exhibited remarkable spontaneous regrowth of trees compared to surrounding spoil piles. Floristic inventory covered the whole area of the 35 piles, whereas survey on phytosociology and natural regeneration studies were conducted in 70 plots distributed along the 35 piles. Floristic inventory recorded 83 species from 28 botanical families. Herbaceous terricolous plants constituted the predominant species (47.0%), followed by shrubs (26.5%), trees (19.3%), and vines (7.2%). Results from surveys on phytosociology and natural regeneration, focused on shrubs and trees, recorded incipient ecological succession. In addition, the most adapted species recorded on the overburden piles, as ranked by index of natural regeneration (RNT) plus importance value index (IVI), were as follows: Clethra scabra (RNT = 23.93%; IVI = 17.28%), Myrsine coriacea (RNT = 20.93%, IVI = 11.26%), Eupatorium intermedium (RNT = 7.56%, IVI = 0.40%), Miconia ligustroides (RNT = 5.84%, IVI = 2.37%), Ossaea amygdaloides (RNT = 3.84%, IVI = 1.30%), Tibouchina sellowiana (RNT = 3.29%, IVI = 1.94%), Eup. inulaefolium (RNT = 2.65%, IVI = 0.80%), and Baccharis dracunculifolia (RNT = 2.28%; IVI = 0.56%). High values of IVI and RNT exhibited by the exotic species Eucalyptus saligna (IVI = 21.73%, RNT = 51.41%) indicated strong competition between exotic and indigenous species. Severe chemical (acidic pH and lack of nutrients) and physical (coarse substrate and slope angle of 40–50°) characteristics displayed by the overburden piles constituted limitations to floristic diversity and size of indigenous trees, indicating the need for substrate reclamation prior to forest restoration.

Summary 1. Spontaneous succession is often underappreciated in restoration after the cessation of intensive agricultural management. Spontaneous succession could improve the success of restoration programmes, and offers a cost-effective option with little active intervention. 2. We studied the spontaneous recovery of loess grasslands in extensively managed lucerne Medicago sativa fields mown twice a year using space for time substitutions to highlight the importance of spontaneous processes in grassland restoration. 3. With increasing field age a gradual replacement of lucerne by perennial native grasses and forbs and increase of mean species richness was detected. As the age of fields increased, lucerne decreased from 75% to 2% of total vegetation cover, whereas perennial graminoids increased from 0AE 5t o 50% cover. Mean total cover showed no significant differences between the age groups; weed cover was less than 10%. 4. The phytomass of lucerne was negatively correlated with graminoid phytomass. As the age of the fields increased, lucerne phytomass decreased and grass phytomass increased. We found a negative correlation between litter and forb phytomass but there was no relationship with the age of the field. There was no litter accumulation and no increase of mean total phytomass as the age of fields increased. 5. Synthesis and applications. Native grasses within loess grasslands recovered within 10 years, but characteristic native forbs remained rare. The advantages of spontaneous succession in lucerne fields compared to technical reclamation include: (i) no early stages dominated by weeds, (ii) minimal litter accumulation, (iii) a spontaneous decrease in lucerne over time, and (iv) negligible cost. In addition, the requirement for twice yearly mowing in the early years will guarantee farmer involvement because of the high forage value of lucerne. The complete restoration of species rich grasslands will require more active management such as propagule transfer by hay and ⁄ or moderate grazing to encourage the return of native forbs.

Summary 1. The view of post-mining sites is rapidly changing among ecologists and conservationists, as sensitive restoration using spontaneous succession may turn such sites into biodiversity refuges in human-exploited regions. However, technical reclamation, consisting of covering the sites by topsoil, sowing fast-growing herb mixtures and planting trees, is still commonly adopted. Until now, no multi-taxa study has compared technically reclaimed sites and sites left with spontaneous succession. 2. We sampled communities of vascular plants and 10 arthropod groups in technically reclaimed and spontaneously restored plots in limestone quarries in the Bohemian Karst, Czech Republic. For comparison, we used paired t-tests and multivariate methods, emphasizing red-list status and habitat specialization of individual species. 3. We recorded 692 species of target taxa, with a high proportion of red-listed (10%) and xeric specialist (14%) species, corroborating the great conservation potential of the quarries. 4. Spontaneously restored post-mining sites did not differ in species richness from the technical reclaimed sites but they supported more rare species. The microhabitat cover of leaf litter, herbs and moss, were all directly influenced by the addition of topsoil during reclamation. 5.Synthesis and applications. Our results show that the high conservation potential of limestone quarries could be realized by allowing succession to progress spontaneously with minimal intervention. Given the threat to semi-natural sparsely vegetated habitats in many regions, active restoration measures at post-mining sites should be limited to maintenance of early successional stages, instead of acceleration of succession.

Strip-mining operations greatly disturb soil, vegetation and landscape elements, causing many ecological and environmental problems. Establishment of vegetation is a critical step in achieving the goal of ecosystem restoration in mining areas. At the Shouyun Iron Ore Mine in suburban Beijing, China, we investigated selective vegetation and soil traits on a tailings dam 7 years after site treatments with three contrasting approaches: (1) soil covering (designated as SC), (2) application of a straw mat, known as “vegetation carpet”, which contains prescribed plant seed mix and water retaining agent (designated as VC), on top of sand piles, and (3) combination of soil covering and application of vegetation carpet (designated as SC+VC). We found that after 7 years of reclamation, the SC+VC site had twice the number of plant species and greater biomass than the SC and VC sites, and that the VC site had a comparable plant abundance with the SC+VC site but much less biodiversity and plant coverage. The VC site did not differ with the SC site in the vegetation traits, albeit low soil fertility. It is suggested that application of vegetation carpet can be an alternative to introduction of topsoil for treatment of tailings dam with fine-structured substrate of ore sands. However, combination of topsoil treatment and application of vegetation carpet greatly increases vegetation coverage and plant biodiversity, and is therefore a much better approach for assisting vegetation establishment on the tailings dam of strip-mining operations. While application of vegetation carpet helps to stabilize the loose surface of fine-structured mine wastes and to introduce seed bank, introduction of fertile soil is necessary for supplying nutrients to plant growth in the efforts of ecosystem restoration of mining areas.

Spoil banks generated during coal mining are usually reclaimed by layering of fertile soil over original barren clay (co called indirect reclamation). This well-proven method is effective from the aspect of vegetation establishment and production, but it is very expensive. Direct reclamation of spoil bank clay promises much cheaper approach, yet its success is uncertain and the process might be rather long-term. This two-year field study aimed to assess the effect of application of commercially produced inoculum of arbuscular mycorrhizal fungi (AMF) Symbivit® on growth of two plant species commonly used for reclamation ( Lotus corniculatus and Arrhenatherum elatius ) sown on three different substrates: organic substrate (mixture of papermill waste, tree-bark and compost) and loess (both substrates typical for indirect reclamation) and original spoil bank clays (simulation of direct reclamation). On organic substrate and loess, A. elatius outcompeted the legume and established 100 % cover in all treatments. The effect of mycorrhizal inoculation was not observed. In contrast, on clay both species established successfully. The produced biomass and cover were, however, substantially lower compared to organic substrate and loess. In clay the positive effect of introduced AMF on plant was observed. Mycorrhizal inoculation was useful for supporting plant growth at direct reclamation. Direct reclamation in itself seems suitable for small-scale application, i.e. in patches where indirect reclamation is inconvenient or more diverse vegetation is required. Key words: arbuscular mycorrhizal fungi; inoculum; clay; papermill waste; loess; Arrhenatherum elatius ; Lotus corniculatus

Post‐mining restoration sites often develop novel ecosystems as soil conditions are completely new and ecosystem assemblage can be spontaneous even on afforested sites. This study presents results from long‐term monitoring and evaluation of an afforested oil‐shale quarry in Estonia. The study is based on chronosequence data of soil and vegetation and comparisons are made to similar forest site‐types used in forest management in Estonia. After site reclamation, soil development lowered pH and increased N, K, and organic C content in soil to levels similar to the common Hepatica forest site‐type but P, total C, and pH were more similar to the Calamagrostis forest site‐type. Vegetation of the restoration area differed from that on common forest sites; forest stand development was similar to the Hepatica forest‐type. A variety of species were present that are representive of dry and wet sites, as well as infertile and fertile sites. It appears that novel ecosystems may be developing on post‐mining reclaimed land in Northeast Estonia and may require adaptations to typical forest management regimes that have been based on site‐types. Monitoring and evaluation gives an opportunity to plan further management activities on these areas.

Lessons learned from the study of ecological succession have much to offer contemporary environmental problem solving but these lessons are being underutilized. As anthropogenic disturbances increase, succession is more relevant than ever. In this review, we suggest that succession is particularly suitable to address concerns about biodiversity loss, climate change, invasive species, and ecological restoration. By incorporating modern experimental techniques and linking results across environmental gradients with meta-analyses, studies of succession can substantially improve our understanding of other ecological phenomena. Succession can help predict changes in biodiversity and ecosystem services impacted by invasive species and climate change and guide manipulative responses to these disruptions by informing restoration efforts. Succession is still a critical, integrative concept that is central to ecology.

In order to identify suitable pioneer plant species for future revegetation of coal gob piles, a field survey was conducted to assess the success of different revegetation species and their influence on soil development nine years after initial planting on a reclaimed coal gob pile in the Yangquan mining area of Shanxi province, China. Data were analyzed using a quantitative classification method (TWINSPAN), ordination techniques (DCA and DCCA), Principal Component Analysis (PCA) and a geo-accumulation index (Igeo). The results revealed that the low levels of soil moisture and available N were the major limiting factors affecting plant community development on the coal gob pile, not metal toxicity. The plant communities that developed had significantly improved the topsoil (0-10cm) quality on the reclaimed coal gob pile nine years after initial planting (p<0.05), but the degree of improvement varied greatly with different planted species. Revegetation types comprised of the planted leguminous species, Medicago sativa and Amorpha fruticosa, and the non-leguminous species, Populus tomentosa and Salix babylonica had the best ecological restoration effects on the reclaimed coal gob pile. Revegetation using these species is therefore recommended for future reclamation of abandoned coal gob piles in this region.

Headwaters and small streams are crucial components of riverine systems, harbouring many highly specialized and unique invertebrate species. Unfortunately, the overwhelming majority of the Central European lowland headwaters are channelized, eutrophicated and/or polluted, and many related species have become critically endangered. Artificial streams established to drain some post-mining sites supplement a network of headwaters and generally do not suffer from agricultural pollution. Nevertheless, the biodiversity and conservation potential of the streams at post-mining sites has never been evaluated. We studied the biodiversity of dragonflies and damselflies (Odonata) at 53 sections (30 m) of an extraordinarily dense system of drainage ditches at a large lignite spoil heap in the Czech Republic. We recorded 22 dragonfly species, of which eight are threatened according to the national Red List. Moreover, four of them are closely associated with the endangered environment of small streams. Overall diversity was generally low at very tiny and/or narrowed streams and was also strongly reduced by high water velocity, high bankside inclination and dominance of expansive common reeds. Sufficient cover of rather shallow sediment layers strongly supports the studied diversity indicators. We thus conclude that post-mining streams in drainage ditches could have a strong potential to offer secondary habitats for threatened headwater biodiversity. However, intermittent reed suppression and the establishment of gently sloping banks and a structured stream bottom are necessary measures for maximizing post-mining stream conservation.

Although there is growing evidence that post-industrial barrens such as quarries can harbour a substantial proportion of species diversity formerly associated with traditional rural landscapes, most of the evidence originated from limestone quarries in relatively warm areas, while minimum studies exist for cool regions and acidic substrates. We used pitfall trapping to study spiders colonising three quarries in a piedmont region of southwestern Czech Republic. We compare samples from the quarries with adjoining seminatural localities using both univariate and multivariate analyses. Samples from the quarries contained less species per trap, but endangered species occurred both in the quarries and outside of them, and some were sampled in the quarries only. Compared to the seminatural localities, quarries were colonised by species preferring lighter and more open vegetation. These species had, in average, more restricted distribution in the Czech Republic, suggesting that the quarries indeed attracted specialists of early successional habitats that are increasingly rare in modern landscapes. Prospects of such species depend on future restoration policy in existing quarries. To safeguard them, spontaneous succession should be preferred over engineered reclamation. Copyright © 2007 John Wiley & Sons, Ltd.

Abstract This paper presents an evaluation of changes in the performance of the surface of the Velka Podkrusnohorska dump, a brown coal waste dump, over a period of 25 years from 1984 to 2009, on the basis of satellite data collected by the Landsat satellite. The changes in vegetation cover, surface moisture and surface temperature were evaluated on the basis of the NDVI index (Normalized Difference Vegetation Index), the NDMI index (Normalized Difference Moisture Index) and the Landsat satellite thermal band. Due to the intense piling up of extracted material and the removal of vegetation cover, there was a significant increase in surface temperature and a decline in NDVI and NDMI after the study of the dump territory began. The maximum surface temperatures and the minimum values of both indices were established in 2000. The trend of the changes in these values has reversed since 2000, due to intensive reclamation works as well as natural succession. The results indicate a significant role of vegetation cover in the formation of the surface temperature and moisture parameters, and the transformation of solar energy at the surface. We consider that the removal of vegetation cover over vast areas can have an impact on the regional climate and hydrological regime. Moreover, we recommend that emphasis be placed on this effect when planning structures for mining purposes.

Abstract Despite the ecological value of unreclaimed post-mining areas, in the Czech Republic, however, rigorous technical reclamation still prevails. Such an approach usually leads to a more uniform environment and destroys the habitat diversity of successional sites, including the variety of water bodies that are crucial habitats for many aquatic and semiaquatic species. The aim of our study was to assess the water environment on reclaimed and unreclaimed post-mining sites from an “amphibian point of view”. We compared the proportion of water habitat area, the number of ponds and their habitat features on 14 technically reclaimed and 6 unreclaimed sections of spoil banks in the North Bohemian brown coal basin in the Czech Republic. The proportion of water area, number of ponds per hectare of spoil bank, and number of ponds in a vicinity of 300 m were significantly higher on successional sections than on reclaimed sections of spoil banks. We also found on successional areas a higher proportion of smaller shallow ponds, with gentle shore slopes, partial insolation of water surface and partial vegetation cover. The ponds on technically reclaimed parts of spoil banks were larger and deeper, with steeper shore slopes, full insolation and partial vegetation cover. We conclude that primary succession leads to a more preferable environment for amphibians than does technical reclamation, and it should be considered as an equal type of post-mining site restoration.