Changes versus homeostasis in alpine and sub-alpine vegetation over three decades in the sub-arctic

Plant species distributions are expected to shift and diversity is expected to decline as a result of global climate change, particularly in the Arctic where climate warming is amplified. We have recorded the changes in richness and abundance of vascular plants at Abisko, sub-Arctic Sweden, by re-sampling five studies consisting of seven datasets; one in the mountain birch forest and six at open sites. The oldest study was initiated in 1977-1979 and the latest in 1992. Total species number increased at all sites except for the birch forest site where richness decreased. We found no general pattern in how composition of vascular plants has changed over time. Three species, Calamagrostis lapponica, Carex vaginata and Salix reticulata, showed an overall increase in cover/frequency, while two Equisetum taxa decreased. Instead, we showed that the magnitude and direction of changes in species richness and composition differ among sites.     

Challenges in assessing biological recovery from acidification in Swedish lakes

Since the 1980s, Swedish lakes have in general become less acidified. Assessment of biological recovery is, however, hampered by poor pre-acidification data, confounding effects of climate change, and few lakes with annual sampling of fish and other organisms. Only three critically acidified, but non-limed, lakes had two decades of fish monitoring. The lakes had not yet recovered to pre-industrial chemical targets. Fish had low species richness compared to other organism groups. Roach (Rutilus rutilus) and/or European perch (Perca fluviatilis) were the dominant fish species, and the acid-sensitive roach had been lost from one of the lakes. Calcium decreased, possibly approaching pre-acidification concentrations, but exceeded minimum levels needed to sustain some Daphnia species. High or increasing levels of total organic carbon, likely due to reduced acidification and climate change, might influence the biological communities in unexpected ways, for example, facilitating more frequent occurrence of the invasive algae Gonyostomum semen.     

Replacing monocultures with mixed-species stands: Ecosystem service implications of two production forest alternatives in Sweden

Whereas there is evidence that mixed-species approaches to production forestry in general can provide positive outcomes relative to monocultures, it is less clear to what extent multiple benefits can be derived from specific mixed-species alternatives. To provide such insights requires evaluations of an encompassing suite of ecosystem services, biodiversity, and forest management considerations provided by specific mixtures and monocultures within a region. Here, we conduct such an assessment in Sweden by contrasting even-aged Norway spruce (Picea abies)-dominated stands, with mixed-species stands of spruce and birch (Betula pendula or B. pubescens), or spruce and Scots pine (Pinus sylvestris). By synthesizing the available evidence, we identify positive outcomes from mixtures including increased biodiversity, water quality, esthetic and recreational values, as well as reduced stand vulnerability to pest and pathogen damage. However, some uncertainties and risks were projected to increase, highlighting the importance of conducting comprehensive interdisciplinary evaluations when assessing the pros and cons of mixtures.     

Phenological development stages variation versus mercury tolerance,accumulation, and allocation in salt marsh macrophytes <Emphasis Type="Italic">Triglochin maritima</Emphasis> and <Emphasis Type="Italic">Scirpus maritimus</Emphasis> prevalent in Ria de Aveiro coastal lagoon (Portugal)

Efficient and sustainable management of rapidly mounting environmental issues has been the focus of current intensive research. The present study aimed to investigate the impact of plant phenological development stage variation on mercury (Hg) tolerance, accumulation, and allocation in two salt marsh macrophytes Triglochin maritima and Scirpus maritimus prevalent in historically Hg-contaminated Ria de Aveiro coastal lagoon (Portugal). Both plant samples and the sediments vegetated by monospecific stands of T. maritima and S. maritimus were collected from reference (R) and sites with moderate (M) and high (H) Hg contamination in Laranjo bay within Ria de Aveiro lagoon. Hg tolerance, uptake, and allocation in T. maritima and S. maritimus, physico-chemical traits (pH, redox potential, and organic matter content) and Hg concentrations in sediments vegetated by these species were impacted differentially by phenological development stages variation irrespective of the Hg contamination level. In T. maritima, Hg concentration increased with increase in Hg contamination gradient where root displayed significantly higher Hg followed by rhizome and leaf maximally at H. However, in S. maritimus, the highest Hg concentration was perceptible in rhizome followed by root maximally at M. Between the two studied plant species, S. maritimus displayed higher Hg tolerance index (depicted by higher plant dry mass allocated to reproductive stage) and higher available Hg at M (during all growth stages) and H (during senescent stage) when compared to T. maritimus. Both plant species proved to be Hg excluder (low root/rhizome–leaf Hg translocation). Additionally, T. maritima also acted as Hg stabilizer while, S. maritimus as Hg accumulator. It can be inferred from the study that (a) the plant phenological development stage variations significantly influenced plant Hg sensitivity by impacting sediment chemistry, plant growth (in terms of plant dry mass), Hg accumulation, and its subsequent allocation capacity, contingent to Hg contamination gradient; (b) S. maritimus accumulated higher Hg but restricted its translocation to above-ground part using exclusion process at both M and H due to its accelerated growth during Hg-tolerant reproductive/metabolically active phenological development stage greater than its counterpart T. maritima; and (c) the studied salt marsh plants although hailed from the same C3 and monocot group did not necessarily display similar phenotypic plasticity and behavior towards Hg-contaminated scenario during their life cycle.     

Impact of the novel neonicotinoid insecticide Paichongding on bacterial communities in yellow loam and Huangshi soils

Insecticides are widely sprayed in modern agriculture for ensuring the crop yield, which could also lead to contamination and insecticide residue in soils. Paichongding (IPP) is a novel neonicotinoid insecticide and was developed recently in China. Soil bacterial community, diversity, and community composition vary widely depending on environmental factors. As for now, little is known about bacterial species thriving, bacterial community diversity, and structure in IPP-spraying soils. In present study, IPP degradation in yellow loam and Huangshi soils was investigated, and bacterial communities and diversity were examined in soil without IPP spray and with IPP spray through pyrosequencing of 16S ribosomal RNA (rRNA) gene amplicons. The degradation ratio of IPP at 60 days after treatment (DAT) reached 51.22 and 34.01 % in yellow loam and Huangshi soil, respectively. A higher richness of operational taxonomic units (OTUs) was found in yellow loam soil (867 OTUs) and Huangshi soil (762 OTUs) without IPP spray while OUTs were relatively low in IPP-spraying soils. The community composition also differed both in phyla and genus level between these two environmental conditions. Proteobacteria, Firmicutes, Planctomycetes, Chloroflexi, Armatimonadetes, and Chlorobi were stimulated to increase after IPP application, while IPP inhibited the phyla of Bacteroidetes, Actinobacteria, and Acidobacteria.     

Natural forest expansion on reclaimed coal mines in Northern Spain: the role of native shrubs as suitable microsites

The characterization of suitable microsites for tree seedling establishment and growth is one of the most important tasks to achieve the restoration of native forest using natural processes in disturbed sites. For that, we assessed the natural Quercus petraea forest expansion in a 20-year-old reclaimed open-cast mine under sub-Mediterranean climate in northern Spain, monitoring seedling survival, growth, and recruitment during 5 years in three contrasting environments (undisturbed forest, mine edge, and mine center). Seedling density and proportion of dead branches decreased greatly from undisturbed forest towards the center of the mine. There was a positive effect of shrubs on Q. petraea seedling establishment in both mine environments, which increase as the environment undergoes more stress (from the mine edge to the center of the mine), and it was produced by different shrub structural features in each mine environment. Seedling survival reduction through time in three environments did not lead to a density reduction because there was a yearly recruitment of new seedlings. Seedling survival, annual growth, and height through time were greater in mine sites than in the undisturbed forest. The successful colonization patterns and positive neighbor effect of shrubs on natural seedlings establishment found in this study during the first years support the use of shrubs as ecosystem engineers to increase heterogeneity in micro-environmental conditions on reclaimed mine sites, which improves late-successional Quercus species establishment.     

Accumulation of Cr,Cd, Pb,Cu, and Zn by plants in tanning sludge storage sites: opportunities for contamination bioindication and phytoremediation

Tanning sludge enriched with high concentrations of Cr and other metals has adverse effects on the environment. Plants growing in the metalliferous soils may have the ability to cope with high metal concentrations. This study focuses on potentials of using native plants for bioindication and/or phytoremediation of Cr-contaminated sites. In the study, we characterized plants and soils from six tanning sludge storage sites. Soil in these sites exhibited toxic levels of Cr (averaged 16,492 mg kg^?1) and other metals (e.g., 48.3 mg Cu kg^?1, 2370 mg Zn kg^?1, 44.9 mg Pb kg^?1, and 0.59 mg Cd kg^?1). Different metal tolerance and accumulation patterns were observed among the sampled plant species. Phragmites australis, Zephyranthes candida, Cynodon dactylon, and Alternanthera philoxeroides accumulated moderate-high concentrations of Cr and other metals, which could make them good bioindicators of heavy metal pollution. High Cr and other metal concentrations (e.g., Cd and Pb) were found in Chenopodium rubrum (372 mg Cr kg^?1), Aster subulatus (310 mg Cr kg^?1), and Brassica chinensis (300 mg Cr kg^?1), being considered as metal accumulators. In addition, Nerium indicum and Z. candida were able to tolerate high concentrations of Cr and other metals, and they may be used as preferable pioneer species to grow or use for restoration in Cr-contaminated sites. This study can be useful for establishing guidelines to select the most suitable plant species to revegetate and remediate metals in tanning sludge-contaminated fields.     

The impact of climate change and aquatic salinization on mangrove species in the Bangladesh Sundarbans

This paper investigates the possible impacts of climate change on aquatic salinity and mangrove species in the Bangladesh Sundarbans. The impact analysis combines the salinity tolerance ranges of predominant mangrove species with aquatic salinity measures in 27 scenarios of climate change by 2050. The estimates indicate significant overall losses for Heritiera fomes; substantial gains for Excoecaria agallocha; modest changes for Avicennia alba, A. marina, A. officinalis, Ceriops decandra, and Sonneratia apetala; and mixed results for species combinations. Changes in mangrove stocks are likely to change the prospects for forest-based livelihoods. The implications for neighboring communities are assessed by computing changes in high-value mangrove species for the five sub-districts in the Sundarbans. The results of the impact analysis indicate highly varied patterns of gain and loss across the five sub-districts. Overall, however, the results suggest that salinity-induced mangrove migration will have a strongly regressive impact on the value of timber stocks because of the loss of highest value timber species, Heritiera fomes. In addition, the augmented potential for honey production will likely increase conflicts between humans and wildlife in the region.     

Climate change,phenology, and butterfly host plant utilization

Knowledge of how species interactions are influenced by climate warming is paramount to understand current biodiversity changes. We review phenological changes of Swedish butterflies during the latest decades and explore potential climate effects on butterfly–host plant interactions using the Orange tip butterfly Anthocharis cardamines and its host plants as a model system. This butterfly has advanced its appearance dates substantially, and its mean flight date shows a positive correlation with latitude. We show that there is a large latitudinal variation in host use and that butterfly populations select plant individuals based on their flowering phenology. We conclude that A. cardamines is a phenological specialist but a host species generalist. This implies that thermal plasticity for spring development influences host utilization of the butterfly through effects on the phenological matching with its host plants. However, the host utilization strategy of A. cardamines appears to render it resilient to relatively large variation in climate.     

Endogenous <Emphasis Type="Italic">trans</Emphasis>-zeatin content in plants with different metal-accumulating ability: a field survey

A field survey was conducted to evaluate soil metal pollution and endogenous trans-zeatin content in the leaves of plants growing at six sites in a metal-polluted area located in Gejiu, Yunnan, China. Five plant species were collected, and the physicochemical properties and concentrations of five metals in the soil were analyzed. The trans-zeatin content in plant leaves was measured by high-performance liquid chromatography. Based on the Nemerow pollution index, the six sites were classified into four levels of pollution (i.e., low, medium, high, and severely high). The degree of soil metal pollution was cadmium (Cd) > arsenic (As) > lead (Pb) > zinc (Zn) > copper (Cu). The leaf trans-zeatin content in Pteris vittata (an arsenic hyperaccumulator) increased significantly by 98.6 % in soil with a severely high level of pollution compared with soil at a low level of pollution. However, in non-hyperaccumulators Bidens pilosa var. radiata and Ageratina adenophora, a significant decrease in leaf trans-zeatin content of 35.6 and 87.6 %, respectively, was observed. The leaf trans-zeatin content in Artemisia argyi also decreased significantly by 73.6 % in high metal-polluted soil compared with that in medium metal-polluted soil. Furthermore, significant correlations were observed between leaf trans-zeatin content in Pteris vittata and As, Pb, and Cd concentrations in the soil; however, either no correlation or a negative one was observed in the other plant species. Therefore, a high content of trans-zeatin in the leaves of Pteris vittata may play an important role in its normal growth and tolerance to metals.     

Heavy metal and trace elements in riparian vegetation and macrophytes associated with lacustrine systems in Northern Patagonia Andean Range

Vegetation associated with lacustrine systems in Northern Patagonia was studied for heavy metal and trace element contents, regarding their elemental contribution to these aquatic ecosystems. The research focused on native species and exotic vascular plant Salix spp. potential for absorbing heavy metals and trace elements. The native species studied were riparian Amomyrtus luma, Austrocedrus chilensis, Chusquea culeou, Desfontainia fulgens, Escallonia rubra, Gaultheria mucronata, Lomatia hirsuta, Luma apiculata, Maytenus boaria, Myrceugenia exsucca, Nothofagus antarctica, Nothofagus dombeyi, Schinus patagonicus, and Weinmannia trichosperma, and macrophytes Hydrocotyle chamaemorus, Isöetes chubutiana, Galium sp., Myriophyllum quitense, Nitella sp. (algae), Potamogeton linguatus, Ranunculus sp., and Schoenoplectus californicus. Fresh leaves were analyzed as well as leaves decomposing within the aquatic bodies, collected from lakes Futalaufquen and Rivadavia (Los Alerces National Park), and lakes Moreno and Nahuel Huapi (Nahuel Huapi National Park). The elements studied were heavy metals Ag, As, Cd, Hg, and U, major elements Ca, K, and Fe, and trace elements Ba, Br, Co, Cr, Cs, Hf, Na, Rb, Se, Sr, and Zn. Geochemical tracers La and Sm were also determined to evaluate contamination of the biological tissues by geological particulate (sediment, soil, dust) and to implement concentration corrections.     

Microbial communities in pesticide-contaminated soils in Kyrgyzstan and bioremediation possibilities

In Kyrgyzstan, many former storehouses and dump sites for obsolete pesticides exist. In 2009/2010, an inventory and assessment of these sites including risks of environmental hazard has been conducted by FAO and the World Bank. Monitoring revealed high concentration of pesticides listed as persistent organic pollutants (POPs). The purpose of this research was to study the microbial structural complexes of the pesticide-contaminated soils in these dumping zones, and to search for and select microorganism’s destructors with cytochrome P450 genes for pesticide degradation. Culture-dependent and culture-independent approaches were used to determine the taxonomic composition of these bacterial communities. The universal primer set for the 16S ribosomal RNA (rRNA) gene and the specific primer set P450R were used to amplify the cytochrome P450 hydroxylase gene. In soils from Suzak A and B and soils from Balykchy dumping sites, the bacteria from the Actinobacteria phylum (Micrococcus genus) were dominant. These bacteria made up 32–47% of the indigenous local microflora; bacteria species from the Pseudomonas genus (Gammaproteobacteria phylum) made up 23% in Suzak, 12% in Balykchy soils. Bacillus species from the Firmicutes phylum were found only in Suzak soils. The 16S rRNA analyses and the specific primer set P450R have revealed bacteria with cytochrome genes which are directly involved in the degradation process of organic carbon compounds. Experiments were carried out to help select active degraders from the bacterial populations isolated and used to degrade Aldrin in laboratory. Active bacterial strains from the Pseudomonas fluorescens and Bacillus polymyxa population were selected which demonstrated high rates of degradation activity on Aldrin.     

Proximate composition and mineral contents in the body wall of two species of sea cucumber from Oman Sea

The proximate composition and mineral contents of Stichopus horrens and Holothuria arenicola from Chabahar Bay were analyzed and investigated. During the present study, we aimed to demonstrate the nutritive value. The approximate percent composition of moisture, protein, fat, and ash were 92.8, 3.47, 0.4, and 3.33% in S. horrens and 93, 4.4, 0.6, and 2% in H. arenicola, respectively. Atomic absorption spectrophotometry of the ashes indicated the body wall of two species of sea cucumbers contained higher amounts of both macro minerals (92.5 mg/100 g Mg in S. horrens and 115 mg/100 g Mg in H. arenicola; 106.25 mg/100 g Ca in S. horrens and 83.25 mg/100 g Ca in H. arenicola) and trace elements (521.781 mg/100 g Fe in S. horrens; 60.354 mg/100 g Fe in H. arenicola, and 0.096 mg/100 g Zn in S. horrens; 0.04 mg/100 g Zn in H. arenicola). For both species, there were high content of protein and essential mineral. Also, they have low content of fat in the body wall of two species in the experiment.     

Plant species affect colonization patterns and metabolic activity of associated endophytes during phytoremediation of crude oil-contaminated soil

Plants coupled with endophytic bacteria hold great potential for the remediation of polluted environment. The colonization patterns and activity of inoculated endophytes in rhizosphere and endosphere of host plant are among the primary factors that may influence the phytoremediation process. However, these colonization patterns and metabolic activity of the inoculated endophytes are in turn controlled by none other than the host plant itself. The present study aims to determine such an interaction specifically for plant-endophyte systems remediating crude oil-contaminated soil. A consortium (AP) of two oil-degrading endophytic bacteria (Acinetobacter sp. strain BRSI56 and Pseudomonas aeruginosa strain BRRI54) was inoculated to two grasses, Brachiaria mutica and Leptochloa fusca, vegetated in crude oil-contaminated soil. Colonization patterns and metabolic activity of the endophytes were monitored in the rhizosphere and endosphere of the plants. Bacterial augmentation enhanced plant growth and crude oil degradation. Maximum crude oil degradation (78 %) was achieved with B. mutica plants inoculated with AP consortium. This degradation was significantly higher than those treatments, where plants and bacteria were used individually or L. fusca and endophytes were used in combination. Moreover, colonization and metabolic activity of the endophytes were higher in the rhizosphere and endosphere of B. mutica than L. fusca. The plant species affected not only colonization pattern and biofilm formation of the inoculated bacteria in the rhizosphere and endosphere of the host plant but also affected the expression of alkane hydroxylase gene, alkB. Hence, the investigation revealed that plant species can affect colonization patterns and metabolic activity of inoculated endophytic bacteria and ultimately the phytoremediation process.     

Phytoextraction of rare earth elements in herbaceous plant species growing close to roads

The aim of study was to determine the phytoextraction of rare earth elements (REEs) to roots, stems and leaves of five herbaceous plant species (Achillea millefolium L., Artemisia vulgaris L., Papaver rhoeas L., Taraxacum officinale and Tripleurospermum inodorum), growing in four areas located in close proximity to a road with varied traffic intensity. Additionally, the relationship between road traffic intensity, REE concentration in soil and the content of these elements in plant organs was estimated. A. vulgaris and P. rhoeas were able to effectively transport REEs in their leaves, independently of area collection. The highest content of REEs was observed in P. rhoeas leaves and T. inodorum roots. Generally, HREEs were accumulated in P. rhoeas roots and leaves and also in the stems of T. inodorum and T. officinale, whereas LREEs were accumulated in T. inodorum roots and T. officinale stems. It is worth underlining that there was a clear relationship between road traffic intensity and REE, HREE and LREE concentration in soil. No positive correlation was found between the concentration of these elements in soil and their content in plants, with the exception of T. officinale. An effective transport of REEs from the root system to leaves was observed, what points to the possible ability of some of the tested plant species to remove REEs from soils near roads.     

Long-term persistence of seeded grass species: an unwanted side effect of ecological restoration

Spoil heaps are the visible footprint of hydropower production, particularly in vulnerable alpine environments. Speeding up vegetation development by seeding commercial grass species has been a common restoration practice for the last 50 years, but we lack information on whether seeded species decline and allow native plant cover to develop. We visually estimated cover of native vascular plants and five seeded grass species (Agrostis capillaris, Festuca ovina, Festuca rubra, Schedonorus pratensis and Phleum pratense) on eight spoil heaps at different elevations (boreal–alpine zone) in western Norway. Spoil heap vegetation was censused twice (9–20 and 24–36 years after spoil heap construction); the undisturbed surrounding vegetation was also censused on the second occasion. Total cover on the spoil heaps showed some increase, but remained far below that in surrounding areas. Cover of seeded grass species in the surroundings was low (but not negligible), indicating suboptimal establishment ability. Seeded species usually covered less than 20 % of the spoil heaps, and only F. rubra, F. ovina and A. capillaris contributed substantially. Proportional cover indicated better initial establishment by seeded species, but their cover decreased between the censuses on all but the highest located spoil heap. The persistence of seeded grass species is problematic, and despite the decrease in proportional cover, they are likely to persist for decades on spoil heaps, posing a risk of invasion of surrounding areas. We therefore recommend replacing the practice of seeding with more appropriate restoration measures.     

Acute,chronic and biochemical effects of chlorothalonil on <Emphasis Type="Italic">Agalychnis callidryas</Emphasis>, <Emphasis Type="Italic">Isthmohyla pseudopuma</Emphasis> and <Emphasis Type="Italic">Smilisca baudinii</Emphasis> tadpoles

Declines of amphibian populations have been a worldwide issue of concern for the scientific community during the last several decades. Efforts are being carried out to elucidate factors related to this phenomenon. Among these factors, pathogens, climate change, and environmental pollution have been suggested as possible causes. Regarding environmental pollutants, some pesticides are persistent in the environment and capable of being transported long distances from their release point. In Costa Rica, some pesticides have been detected in protected areas, at locations where amphibian populations have declined. Information about toxicity of pesticides used in Costa Rican agriculture to amphibians is still scarce, particularly for native species.Toxicity tests with chlorothalonil, a fungicide intensively used in Costa Rica, were carried out exposing tadpoles of three Costa Rican native species: Agalychnis callidryas, Isthmohyla pseudopuma, and Smilisca baudinii in order to evaluate acute and chronic toxicity as well as the biomarkers cholinesterase activity (ChE), glutathione-S transferase activity (GST), and lipid peroxidation (LPO).96-h LC₅₀: 26.6 (18.9–35.8) μg/L to A. callidryas, 25.5 (21.3–29.7) μg/L to I pseudopuma and 32.3 (26.3–39.7) μg/L to S. baudinii were determined for chlorothalonil. These three species of anurans are among the most sensitive to chlorothalonil according to the literature. Besides, GST was induced in S. baudinii after exposure to sub-lethal concentrations of chlorothalonil while evisceration occurred in S. baudinii and A. callidryas tadpoles exposed to lethal concentrations of the fungicide. Chronic exposure to sub-lethal concentrations accelerated development in S. baudinii and caused lesions in tail of S. baudinii and I. pseudopuma tadpoles. Our results demonstrate that chlorothalonil is highly toxic to native amphibian species and that low concentrations can cause biochemical responses related to phase II of biotransformation and effects on development.     

Evaluation of air pollution tolerance index and anticipated performance index of plants and their application in development of green space along the urban areas

Air pollution due to vehicular emissions has become one of the most serious problems in the whole world and has resulted in huge threat to both the environment and the health of living organisms (plants, humans, animals, microorganisms). Plants growing along the roadsides get affected at the maximum as they are the primary recipients to different air pollutants and show varied levels of tolerance and sensitivity. Taking this into account, the present work was based on assessment of seasonal variation in air pollution tolerance index (APTI) and anticipated performance index (API) of four roadside plants, namely, Alstonia scholaris, Nerium oleander, Tabernaemontana coronaria, and Thevetia peruviana belonging to family Apocynaceae. APTI was calculated by the determination of four important biochemical parameters, viz., pH, relative water content (RWC), total chlorophyll (TChl), and ascorbic acid (AsA) content of leaves. The leaf samples were collected from plants growing at seven different sites of Amritsar (Punjab), India, for pre-monsoon and post-monsoon seasons. Highest APTI (82.14) was reported in N. oleander during the pre-monsoon season while the lowest was recorded in T. coronaria (18.59) in the post-monsoon season. On the basis of API score, A. scholaris was anticipated to be an excellent performer during the pre-monsoon and post-monsoon seasons followed by N. oleander, T. coronaria, and T. peruviana. Linear regression analysis and Pearson’s correlation coefficient depicted significant positive correlation between APTI and ascorbic acid content during the pre-monsoon and post-monsoon seasons.     

Potential of copper-tolerant grasses to implement phytostabilisation strategies on polluted soils in South D. R. Congo

Phytostabilisation (i.e. using plants to immobilise contaminants) represents a well-known technology to hamper heavy metal spread across landscapes. Southeastern D.R. Congo, Microchloa altera, a tolerant grass from the copper hills, was recently identified as a candidate species to stabilise copper in the soil. More than 50 grasses compose this flora, which may be studied to implement phytostabilisation strategies. However, little is known about their phenology, tolerance, reproductive strategy or demography. The present study aims to characterize the Poaceae that may be used in phytostabilisation purposes based on the following criteria: their ecological distribution, seed production at two times, abundance, soil coverage and the germination percentage of their seeds. We selected seven perennial Poaceae that occur on the copper hills. Their ecological distributions (i.e. species response curves) have been modelled along copper or cobalt gradients with generalised additive models using logic link based on 172 presence-absence samples on three sites. For other variables, a total of 69 quadrats (1 m²) were randomly placed across three sites and habitats. For each species, we compared the number of inflorescence-bearing stems (IBS) by plot, the percentage of cover, the number of seeds by IBS and the estimated number of seeds by plot between sites and habitat. Three species (Andropogon schirensis, Eragrostis racemosa and Loudetia simplex) were very interesting for phytostabilisation programs. They produced a large quantity of seeds and had the highest percentage of cover. However, A. schirensis and L. simplex presented significant variations in the number of seeds and the percentage of cover according to site.     

Remediation of metalliferous mines,revegetation challenges and emerging prospects in semi-arid and arid conditions

Understanding plant behaviour in polluted soils is critical for the sustainable remediation of metal-polluted sites including abandoned mines. Post-operational and abandoned metal mines particularly in semi-arid and arid zones are one of the major sources of pollution by soil erosion or plant hyperaccumulation bringing ecological impacts. We have selected from the literature 157 species belonging to 50 families to present a global overview of ‘plants under action’ against heavy metal pollution. Generally, all species of plants that are drought, salt and metal tolerant are candidates of interest to deal with harsh environmental conditions, particularly at semi-arid and arid mine sites. Pioneer metallophytes namely Atriplex nummularia, Atriplex semibaccata, Salsola kali, Phragmites australis and Medicago sativa, representing the taxonomic orders Caryophyllales, Poales and Fabales are evaluated in terms of phytoremediation in this review. Phytoremediation processes, microbial and algal bioremediation, the use and implication of tissue culture and biotechnology are critically examined. Overall, an integration of available remediation plant-based technologies, referred to here as ‘integrated remediation technology,’ is proposed to be one of the possible ways ahead to effectively address problems of toxic heavy metal pollution.

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Graphical abstract Integrated remediation technology (IRT) in metal-contaminated semi-arid and arid conditions. The hexagonal red line represents an IRT concept based on remediation decisions by combination of plants and microbial processes.