Ironstone Outcrops Research Articles

Investigating the reproductive strategies of Deuterocohnia meziana (Bromeliaceae), an endangered and restricted species from South American rocky outcrops.

Studies of reproductive biology and resources availability to floral visitors by plant species are important to understand the plant-pollinator interactions that drive species adaptation. We aim to understand the relationship between reproduction mechanisms of Deuterocohnia meziana (Bromeliaceae) and pollinators. The species occurs in Bolivia and Paraguay, and it is the only species of the genus found in Brazil, where it is restricted to ironstone outcrops. These areas are currently threatened by the iron mining industry. Additionally, they face risks from fire occurrence and grazing by cattle. We analyzed the floral biology, reproductive system, phenology, and pollination ecology of a natural population of Deuterocohnia meziana, from ironstone outcrops in Brazil. The species exhibits diurnal anthesis, with stigma receptive throughout anthesis, and 77% of pollen viability. Deuterocohnia meziana produces relatively large amounts of nectar, especially early in the morning (32.8 ± 9.4μl), with a mean sugar concentration of 23.5 (± 3.2) ºBrix. It is self-incompatible with a peak flowering occurring in August (dry season), although flowers are observed continuously throughout the year. The species exhibits two types of inflorescences, young and mature, among which an average of 13.1 and 3.6 flowers open per day, respectively. Hummingbirds and bees are the effective pollinators, although butterflies and ants also visit D. meziana flowers. The species is reliant on exogenous pollen and pollinators for fruit set. The continuous conservation of D. meziana populations and their communities is essential for preserving plant-pollinator mutualism and the floral community adapted to ironstone outcrops.

Vegetation mosaic shaping bryophyte diversity in a threatened ecosystem: A case study of Brazilian Cangas (ferruginous rupestrian fields)

The Canga vegetation in Brazil is a unique ecosystem found on ironstone outcrops, known as ferruginous rupestrian fields, and is considered one of the most diverse in the world. This mosaic landscape, comprised of trees, shrubs, and herbaceous vegetation, is home to a diverse range of plants, including angiosperm, bryophytes, and lichens. To understand the effect of Cangas' patchy landscape, here called mesohabitats, on bryophyte communities, we asked the following questions: Do the diversity parameters such as richness, abundance and composition of bryophytes differ along the different Cangas’ mesohabitats? Do bryophyte assemblages group by functional traits and filter per mesohabitat? We surveyed eight sites in the Quadrilátero Ferrífero (Iron Quadrangle), southeast Brazil. We collected and analysed data on bryophyte diversity and functional traits in three different mesohabitats: exposed areas (EA), shrub associations (SA), and tree associ ations (TA). The diversity of both groups was tested using one-way ANOVA; and functional traits were addressed with a Factorial Analysis of Mixed Data (FAMD). There are significant differences in the diversity of bryophytes among the mesohabitats, with TA having the highest diversity and abundance of liverworts and mosses, followed by SA and EA. The study also found bryophyte assemblies with similar functional traits in similar mesohabitats across the Brazilian Quadrilátero Ferrífero. The research revealed that the different mesohabitats provided important and distinct niches for bryophytes in Cangas, and this threatened ecosystem's high diversity must be considered when developing conservation strategies. This entails land managers adopting effective approaches aimed at improving both the quality and connectivity of habitats, fostering biodiversity, and bolstering the resilience of the ecosystem.

Anatomical adaptations in the stem of Discocactus catingicola (Cactaceae) to the highly threatened ironstone outcrops from southeastern Brazil

The geosystems known as “cangas” are composed of ferruginous concretions and are characterized by being subjected to elevated temperatures and by having highly acidic, shallow, unfertile soils. The extremely harsh environmental conditions therein limit the occupation of cangas to a restricted number of species, such as Discocactus catingicola. We aimed to analyze the stem anatomy of D. catingicola occurring on cangas in order to assess which structural traits provide the species with an adaptive advantage to these geosystems. Stem samples were subjected to protocols of cross-sectioning, epidermal dissociation and lugol histochemical detection, and were then analyzed under light microscopy. Stems have a uniseriate epidermis and a thick cuticle. Paracytic stomata occur at the same level of pavement cells. Conspicuous substomatal chambers extend through the entire hypodermis height. The two-layered, collenchymatous hypodermis has a high amount of calcium oxalate inclusions in the form of prismatic crystals. Stem structure is also composed of a water-storing chlorenchyma, a starch and water storage parenchyma, and wide-band tracheids. Our findings revealed the occurrence of xeromorphic adaptive characters in D. catingicola which provide the species with its adaptive success in ironstone outcrops. The description of these anatomical traits in D. catingicola make up a pioneer report, thus being of great importance for future research on ecological plant anatomy not only of Cactaceae species but also of other unrelated xerophytes. We expect our work will assist researchers in the fields of anatomy, taxonomy and systematics of Cactaceae. Future research investigating the anatomy of D. catingicola populations occurring on ecosystems other than the lateritic cangas should provide a helpful comparative basis for evaluating the species degree of phenotypic plasticity.

Reproductive phenology of critical native plant species for mineland restoration in the eastern Amazon

AbstractAmazon ironstone outcrops vegetation, or canga, is a remarkable environment in which the plants are adapted to peculiar circumstances. Knowledge regarding different aspects of this ecosystem remains modest, including necessary insights for its conservation and recovery, such as the reproductive phenology of priority species that form the plant community. This study aimed to monitor the reproductive phenology of critical native species that are categorized as rare, endemic, and/or threatened in the canga of the Amazon Rainforest, in Pará, Brazil. During February 2016 and May 2017, eleven species were evaluated regarding the presence or absence of flowering and fruiting phenophases, and these were associated with environmental variables. Phenological data were evaluated through circular statistical analysis. All studied species flowered and produced fruit during the monitoring period. The evaluated species have an annual reproductive cycle marked by seasonality and flowering peaks between March and April, during the wet season, and fruiting peaks during May, at the beginning of the dry season. The best period for collecting ripe seeds, a primary tool for the restoration of degraded areas, is June. Water availability may be essential for the establishment of annual plants and to induce flowering in both annual and perennial species. The reproductive phenophases of the studied species are concentrated within a short period and are synchronized, which may increase the possibility of cross‐pollination and minimize flower and seed predation. We discuss the challenges in including annual plants and the importance of having them and perennial species in conservation and restoration of degraded areas projects.

DNA metabarcoding reveals compositional and functional differences in fungal communities among Amazonian canga formations

Fungi execute many ecosystem functions and are thus expected to contribute substantially to ecosystem stability along environmental gradients. Here, we aimed to describe the fungal communities along a vegetation gradient found in Amazonian cangas using ITS2 metabarcoding. Rupestrian canga vegetation covers ironstone outcrops from the Carajás National Forest and the Campos Ferruginosos National Park of the Eastern Amazon. We detected 3574 operational taxonomic unit sequences dominated by the phyla Ascomycota , Basidiomycota , and Glomeromycota . The taxonomic and functional groups differed among periodically inundated grasslands (GR), typical scrublands (SB), Vellozia scrublands (VL), and woodlands (WD). Saprotrophic fungi were the most abundant, occurring primarily in WD, while stress-tolerant lineages and functional groups were dominant in environments with less soil. Our results provide new insights into the fungal ecology on ironstone outcrops and shed light on the importance of these organisms in enabling growth of vegetation cover, promoting species coexistence and increasing degrees of plant diversity in these harsh environments. • Metabarcoding reveals high fungal diversity in Amazonian ironstone outcrops. • Dothideomycetes and Agaricomycetes predominate in soils from canga ecosystems. • Fungal communities differ among canga formations. • Canga ecosystems harbor many fungi tolerant to extreme conditions. • The high number of unidentified OTUs highlights the need for further research.

Can ecological strategies be explained by photochemical efficiency in ironstone outcrops vegetation?

Can ecological strategies be explained by photochemical efficiency in ironstone outcrops vegetation?

Experimental manipulation of biotic and abiotic parameters changes the outcome of insect-plant interactions

Plants usually respond to environmental shifts with morpho-physiological adjustments, which trickles down to biotic interactions in the insect-plant system. We evaluate how Copaifera langsdorffii, a widespread tree species adapted to multiple ecosystems, responds to shifts in nutrient and water availability through experimental supplementation and how it affects its insect communities. We also evaluate how the presence of extrafloral nectaries (EFN) exudates modifies galling insect diversity and herbivory rates. Such experimental approach is scarce, as we simultaneously evaluate biotic and abiotic factors and cover the entire reproductive cycle of a species in natural environments, bringing important contributions to better understand how bottom-up factors drive species interactions and possibly community assembly. The experiment was set in an ironstone outcrop vegetation, where we deployed supplementation treatments in 80 plant individuals divided into the following field treatments: (T1 = Fertilizer, T2 = EFN simulation (Eppendorf tubes with a 20% sugar solution), T3 = fertilizer + EFN simulation, T4 = water spray, T5 = EFN control (microtube with water), and T6 = Control. We observed lower sclerophylly and greater leaf area in plant individuals that were supplemented with nutrients and water. Herbivory rates were lower and ant abundance was higher in plants with artificial EFNs available. While we did not observe variations in richness and abundance of galling insects, the patterns of co-occurrence of galls varied with the availability of resources (nesting space) in the plant. This study illustrates how variations in nutrient availability to plants modify interactions with insect communities. Ant-plant interactions can have a negative impact on general herbivory rates, however ants seem to have a more harmonious relationship with the galling insects.

The importance of pollination and dispersal syndromes for the conservation of Cerrado Rupestre fragments on ironstone outcrops immersed in an agricultural landscape

Studies on pollination and seed dispersal are essential for the conservation of plant diversity. In this study, we aimed to evaluate the pollination and dispersal syndromes of five fragments of the Cerrado Rupestre immersed in an agricultural landscape to answer the following questions: (i) What is the frequency of pollination and dispersal syndromes among species and individuals?; (ii) Which are the predominant pollination and seed dispersal syndromes in this environment?. A total of 66 species, belonging to 44 genera and 29 botanical families, were evaluated. Melittophily was the most common type of pollination syndrome, observed in 54.55% of the species, followed by phalenophily (9.09%), cantharophily, ornithophily, quiropterophilly and sphingophily (all 3.03%), and psychophilly (1.51%). Generalist pollination represented 22.73% of the records. Of the 1246 individuals identified, 59.23% were melitophilous, 25.20% generalists, 5.86% phalenophilous, 3.37% quiropterophilous, 2.49% cantharophilous, 2.25% ornithophilous, 1.44% sphingophilous and 0.16% psychophilous. Regarding dispersion syndromes, zoochory was the most common type of dispersion, observed in 68.18% of the species, followed by anemochory (28.79%) and autochory (3.03%). On the other hand, the frequency among individuals differed from the values found for frequency among species. Of the 1246 individuals identified, 55.38% were anemochoric, 43.10% zoochoric, and 1.52% autochoric. Our results demonstrate the predominance of biotic syndromes in the community, especially melittophily and zoochory, contributing to a better understanding of the functionality and availability of resources in the community, as well as indispensable information for the conservation, management, and restoration of natural environments.

Unraveling the plant diversity of the Amazonian canga through DNA barcoding.

The canga of the Serra dos Carajás, in Eastern Amazon, is home to a unique open plant community, harboring several endemic and rare species. Although a complete flora survey has been recently published, scarce to no genetic information is available for most plant species of the ironstone outcrops of the Serra dos Carajás. In this scenario, DNA barcoding appears as a fast and effective approach to assess the genetic diversity of the Serra dos Carajás flora, considering the growing need for robust biodiversity conservation planning in such an area with industrial mining activities. Thus, after testing eight different DNA barcode markers (matK, rbcL, rpoB, rpoC1, atpF‐atpH, psbK‐psbI, trnH‐psbA, and ITS2), we chose rbcL and ITS2 as the most suitable markers for a broad application in the regional flora. Here we describe DNA barcodes for 1,130 specimens of 538 species, 323 genera, and 115 families of vascular plants from a highly diverse flora in the Amazon basin, with a total of 344 species being barcoded for the first time. In addition, we assessed the potential of using DNA metabarcoding of bulk samples for surveying plant diversity in the canga. Upon achieving the first comprehensive DNA barcoding effort directed to a complete flora in the Brazilian Amazon, we discuss the relevance of our results to guide future conservation measures in the Serra dos Carajás.

Potential of Bacterial Strains Isolated from Ironstone Outcrops Bromeliads to Promote Plant Growth Under Drought Conditions.

Plant growth-promoting bacteria (PGPB) are bacteria that have mechanisms that facilitate plant growth in stress conditions such as drought. The objective of this study was to characterize bacterial strains isolated from bromeliads roots in ironstone outcrops (Urucum Residual Plateau, Mato Grosso do Sul, Brazil) for plant growth-promoting under drought conditions. Firstly, we screened isolates with the presence of 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity. Then, all isolates were tested for tolerance to drought, exopolysaccharides (EPS) production, indole-3-acetic acid (IAA)-producing abilities, phosphate and zinc solubilization, production of catalase and hydrolytic enzymes (amylase, cellulase, and protease). Germination assay and a pot experiment with maize plants submitted to well-watered and drought conditions were performed with the strains most promising (VBN11 and VBE23). Briefly, Bacillus cereus VBE23 showed in vitro higher ACC deaminase activity (3.83 and 2.52 µmol α-KB mg-1h-1 in non-drought and drought conditions, respectively), tolerance to drought, EPS production and other mechanisms of plant growth promotion: solubilization of phosphate and zinc, ammonia production, catalase activity and production of hydrolytic enzymes (amylase, cellulase, and protease). Inoculation of strain VBE23 in maize seeds submitted to drought conditions showed higher germination concerning uninoculated seeds and inoculated with VBN11. Also, the results indicated that the isolate VBE23 provided higher values of fresh and dry biomass compared to the control of uninoculated treatment and inoculated with VBN11 under drought conditions. This is the first report on the PGPB from ironstone outcrops of Urucum Residual Plateau, Mato Grosso do Sul, Brazil. Thus, this bacterial isolate could be used as a strategy for the facilitation of plant growth in drought environments.

What can bryophyte diversity on Cangas (ironstone outcrops) teach us?

AbstractQuestionsBryophytes are a common plant component of the mining‐threatened ironstone outcrops called Cangas, although quite neglected. Aiming to improve conservation strategies for this Brazilian landscape, here we ask: (a) are there differences in species composition, richness and abundance and the role of reproduction (i.e., sexual and asexual expression, and reproductive success) among bryophyte communities of Cangas; and (b) do abiotic and geographic factors influence species composition on these outcrops?LocationEight Canga sites in the Quadrilátero Ferrífero (QF) of the state of Minas Gerais, southeast Brazil.MethodsWe sampled eight Canga sites for bryophyte species composition, richness, abundance, and reproduction (i.e., sexual and asexual expression, reproductive success) using 18 4‐m2 plots per site. Similarities in species composition among sites were assessed by cluster analysis; differences in richness, abundance, and reproduction parameters were tested by ANOVA; and the correlations between species composition and climatic variables, altitude, and geographical distance were tested by the Mantel test.ResultsThe Canga sites had unique species compositions of bryophytes, with only liverwort richness and abundance differing significantly among sites. Nonetheless, there were floristic similarities among certain geographically close sites, and bryophyte composition was not completely explained by either environmental variables or geographical distance. Additionally, sexual, and asexual reproduction did not differ among Cangas.ConclusionsCangas of the Brazilian QF have unique bryophyte communities (i.e., high beta diversity), especially for liverworts. Liverwort composition was found to be strongly affected by threats to Cangas, especially in areas disturbed by intensive fire. We hypothesize that the local landscape and microclimate have a greater influence on bryophyte diversity than regional aspects. Therefore, future conservation efforts on Cangas must emphasize local diversity and the functionality of liverworts and mosses in different habitats, combined with enhanced protection of Conservation Units.

High C-and N-based soil fertility and microbial associations sustain the plant biodiversity of the campo rupestre in Brazil

The campo rupestre vegetation in the Serra do Rola Moça State Park (PESRM) grows on ironstone outcrops, forming vegetation islands where plant species establish belowground interactions. This area is circumscribed by several mining companies and, for mined land rehabilitation purpose, we assessed plant species composition, plat-microbial associations, and soil fertility patterns in a preserved campo rupestre. Aside from high plant biodiversity, we found elevated soil fertility in relation to soil CEC (~18 cmol/dm3), organic matter (~115 g/Kg), soil C (~ 53.3 g/Kg), humic (~12.5 g/Kg) and fulvic (~8.9 g/Kg) acids, soil N (~4 g/kg) and a low C:N ratio (~12). The overall nutrient levels were higher than or comparable to those of other preserved sites in Brazil. The prevalent legume Mimosa calodendron, hosting N-fixing and plant growth-promoting bacteria in its nodules, was considered an N source to the soil, as evidenced by the elevated leaf N content and the greater depletion of leaf δ15N compared to other families. However, leaf N was parsimoniously distributed among biogeochemical islands and within different plant species and families, which was attributed to a common mycorrhizal network (CMN) formed by arbuscular (AMF) and orchid mycorrhizal fungi (OMF), suggested by general root mycorrhizal colonisation and soil phospholipid fatty acid (PLFA) analyses. We revealed that a high C- and N-based soil fertility constitutes a natural pattern of fertility, which is maintained by below-ground associations and is sufficient to sustain plant biodiversity. For rehabilitation purposes, this natural soil fertility of preserved sites should be maintained by integrating the biogeochemical relations involving plant communities and microbial associations.

How does spatial micro‐environmental heterogeneity influence seedling recruitment in ironstone outcrops?

AbstractQuestionsEnvironmental filters limit the set of potentially coexisting species in plant communities. Paradoxically, some of the world's most biodiverse communities are subjected to strong abiotic filters. We explored how environmental heterogeneity provides conditions for niche segregation in a harsh megadiverse ecosystem, focusing on fine‐scale factors that drive seedling recruitment. Due to the environmental stress (mainly nutrient and water scarcity), we expected the prevalence of positive plant interactions over negative ones to contribute to species coexistence.LocationIronstone outcrop (canga) at Serra da Calçada, southeast Brazil.MethodsWe characterised microhabitats with one or neither of two dominant shrubs Mimosa calodendron (Fabaceae) and Lychnophora pinaster (Asteraceae), and assessed which micro‐environmental attributes affect seedling survival, growth, and abundance, as well as adult richness in the ecosystem.ResultsSpatial heterogeneity in the community was mostly driven by differences in substrate properties, and plots with Mimosa calodendron and Lychnophora pinaster exhibited different biotic and abiotic conditions from those lacking these species. Microhabitats under both shrubs had greater adult richness, and those occupied by Mimosa calodendron had greater seedling abundance, suggesting positive effects of environmental conditions associated with these plants. Nevertheless, we identified two potential negative plant–plant interactions: larger crown area of the two dominant shrubs was associated with lower species richness, and greater understorey plant cover with lower seedling abundance. Over one year, 63% of the recorded seedlings survived, but measured attributes failed to predict survival. Seedling relative growth rates were species‐specific and lower in microsites where the rocky substrate is fragmented. The most abundant seedling taxa occurred in association with specific microhabitats.ConclusionsOur study suggested that fine‐scale spatial heterogeneity determines the outcome of plant–plant interactions in a stressful ecosystem. Micro‐environmental heterogeneity allows for the spatial segregation of species recruitment, thereby broadening the range of viable strategies within a harsh megadiverse ecosystem.

Seed Functional Traits Provide Support for Ecological Restoration and ex situ Conservation in the Threatened Amazon Ironstone Outcrop Flora.

Cangas (ironstone outcrops) host a specialized flora, characterized by high degree of edaphic endemism and an apparent lack of natural history knowledge of its flora. Due to intense pressure from iron ore mining this ecosystem is under threat and in need of restoration. We studied seed functional traits that are relevant for restoration, translocation and ex situ conservation in 48 species from cangas in eastern Amazon. Were determined the thermal niche breadth, classified seed dormancy and determined methods to overcome it, determined the effect of seed storage on germination, tested the association between germination traits and functional groups, and tested whether seed traits are phylogenetically conserved. We found a broad interspecific variation in most seed traits, except for seed water content. Large interspecific variation in the temperature niche breadth was found among the studied species, but only four species, showed optimum germination at high temperatures of 35–40°C, despite high temperatures under natural conditions. Only 35% of the studied species produced dormant seeds. Mechanical scarification was effective in overcoming physical dormancy and application of gibberellic acid was effective in overcoming physiological dormancy in five species. For the 29 species that seeds were stored for 24 months, 76% showed decreases in the germination percentage. The weak association between germination traits and life-history traits indicate that no particular plant functional type requires specific methods for seed-based translocations. Exceptions were the lianas which showed relatively larger seeds compared to the other growth-forms. Dormancy was the only trait strongly related to phylogeny, suggesting that phylogenetic relatedness may not be a good predictor of regeneration from seeds in cangas. Our study provides support to better manage seed sourcing, use, storage and enhancement techniques with expected reduced costs and increased seedling establishment success.

Cultivable bacterial diversity associated with bromeliad roots from ironstone outcrops in central Brazil.

Studies on the bacterial diversity associated with wild plants are rare, especially on those that grow in association with bromeliads. In the present study, we isolated and identified epiphytic and endophytic bacteria from the roots of the bromeliads Dyckia excelsa, Dyckia leptostachya and Deuterocohnia meziana occurring in the "cangas" in the Pantanal from Mato Grosso do Sul State, Brazil. The epiphytic bacteria were isolated from washed roots, while the endophytic bacteria were isolated from surface disinfested roots. Bacterial representatives corresponding to each BOX-PCR fingerprint, as well as those that did not result in amplicons, were selected for 16S rDNA gene sequence analysis. The BOX-PCR data showed intrageneric and intraspecific diversity and could discriminate strains and identify their phenotypic characteristics. The 16S rDNA gene sequence and phylogeny analysis showed a higher occurrence of strains belonging to the genus Bacillus than Mycobacterium and Brevibacterium, which were found in lower numbers. Species from the Bacillus genus are well known for their sporulation capacity and longer survival in arid locations, such as the "cangas". This study clearly showed that the bromeliad species represent a vast reservoir of bacterial community diversity, and the cultivable strains represent a new source for biotechnological prospecting.

Landscape heterogeneity and habitat amount drive plant diversity in Amazonian canga ecosystems

Island Biogeography Theory and Habitat Amount Hypothesis postulate species richness and densities to increase with connectivity and habitat amount, while niche theory highlights the importance of environmental heterogeneity for species coexistence. Additional ecological niches in heterogeneous landscapes increase species richness and functional and phylogenetic diversity, but larger, less isolated habitats are expected to enlarge species densities by mass effects without effects on functional or phylogenetic diversity. We assessed the relative contribution of habitat amount, isolation and environmental heterogeneity on taxonomic, functional and phylogenetic diversity of the particular canga vegetation, i.e., rupestrian savannas associated to banded ironstone outcrops from the Carajas Massif, Eastern Amazon. We sampled vegetation at 48 sampling points comprising different physiognomies from 5 canga patches. Diversity measures were modelled as response variables in linear mixed models, using non-collinear predictors of habitat amount, isolation and environmental heterogeneity. Diversity and species composition differed among canga physiognomies, indicating that environmental filters segregate canga plant metacommunity in physiognomy-specific species pools. Landscape roughness, a proxy for heterogeneity on the landscape level, increases species densities and functional richness. Additionally, habitat amount was positively associated with the degree of phylogenetic relatedness and functional diversity in communities. Our results suggest that configurational landscape heterogeneity increases the number of available ecological niches, while larger habitat amounts select for functionally and phylogenetically convergent species. These different underlying mechanisms need to be considered for management plans and reserve design for canga ecosystems, so that functional canga portions can be protected.

Ecological succession in areas degraded by bauxite mining indicates successful use of topsoil

Brazilian ironstone outcrops (cangas) are nutrient‐poor stressful habitat dominated by slow‐growing woody species with high biodiversity and unique evolutionary history. Mining has produced great impacts on this ecosystem. Spontaneous regeneration of abandoned canga mined areas has not been observed. One of the active methods most widely used for ecological restoration in environments where soil has been lost or severely degraded is topsoil transposition due to the physical, chemical, and microbiological improvement of the substrate, in addition to the seed bank. Thus, plant succession was monitored for 40 months after topsoil transposition in a canga area degraded by aluminum mining, without any other type of management. A completely randomized design with 70 permanent plots (1 × 1 m) was used. Annual phytosociological surveys were carried out and floristic and vegetational spectra were constructed with the life‐forms proposed by Raunkiaer. Floristic composition was compared with a reference site. Overall, 105 species were identified. Both flora and vegetation changed over time, increasing resemblance to the reference areas. The floristic and vegetational spectra after 4 years of topsoil deposition are similar to pristine ones. The vegetation spectrum showed an increase in the dominance of phanerophytes and hemicryptophytes, while therophytes reduced their proportion. The early successional stage is dominated by weeds, like in other canga restoration studies, but did not impede the native species regeneration. Cangas's species recruited well from transposed topsoil. Unlike other studies with fertilized topsoil, our findings show the efficiency of topsoil transposition to provide initial conditions for the ecological restoration of this ecosystem.

Vegetation misclassification compromises conservation of biodiversity and ecosystem services in Atlantic Forest ironstone outcrops

A recent state provision allows quarzitic campo rupestre (QCR) set-asides as in-kind compensation for ironstone campo rupestre (ICR) suppression in the Atlantic Forest, which induces out-of-kind compensation. However, the recently published state provision defines no clear parameters to demonstrate “ecological equivalence” as an in-kind compensation. We evaluated whether there is ecological equivalence between and ICR and QCR in the Brazilian Atlantic Forest. We show marked geological, pedological, floristic, structural, and functional differences between ICR and QCR. There is evidence that the new compensation rules only partially offset loss of biodiversity and ecosystem services hosted by ICR, determining limited effectiveness of the legislation for ICR conservation in the Atlantic Forest. We conclude that the development of clear compensation parameters based on scientific evidence and quantitative indicators is a priority gap for the conservation of ICR under increasing mining pressure.

Two new Critically Endangered species of Ditassa (Apocynaceae) from the threatened cangas of the Iron Quadrangle, Minas Gerais, Brazil

Background and aims – Vegetation on ironstone outcrops is highly threatened, particularly due to the impact of mining. In this study, two new species of Ditassa (Metastelmatinae, Asclepiadoideae, Apocynaceae) from the cangas of the Iron Quadrangle (Minas Gerais, Brazil) are described and illustrated, and their conservation status is discussed.Material and methods – Species recognition is based on a morphological and molecular study of recent and historical collections, including a survey of the main herbaria of Brazil, Europe and the United States. Conservation status assessments are based on the evaluation of areas of occupancy and the impact of iron mining in the region.Key results – The two new species are morphologically similar to species in the “Hemipogon from the Espinhaço” clade, which includes Morilloa. Nevertheless, they exhibit flowers with a double corona and are described in Ditassa here, following preliminary phylogenetic analyses with 73 plastid-coding regions. These species are known from only two highly disturbed locations each and are Critically Endangered. A key to identify the 14 species of Metastelmatinae currently recorded in cangas of the Iron Quadrangle is provided.Conclusion – The Critically Endangered Ditassa cangae and D. ferricola are examples of poorly known, nearly extinct species under strong anthropogenic pressure caused by intense mining activities and the lack of adequate legislation for the protection of canga landscapes.

Phosphorus lability increases with the rehabilitation advance of iron mine land in the eastern Amazon

Impacted areas by iron mining may face challenges in the management of phosphate fertilization and reduced efficiency of rehabilitation practices, thus extending the time required for the rehabilitation of these areas. The objective of this study was to evaluate phosphorus (P) lability in soils of native forest and ferriferous canga areas (savanna vegetation above ironstone outcrops covering iron ore deposits) and in iron mine waste piles undergoing rehabilitation. Benches of the analysed waste pile differ in age of rehabilitation: as the initial rehabilitation stage (INI), we consider benches with fewer than 3years of rehabilitation; the intermediate stage (INT) were benches with up to 5years of rehabilitation; and the advanced rehabilitation stage (ADV) corresponds to benches with more than 8years of rehabilitation activities. Organic and inorganic P fractions were analysed in these areas by chemical fractionation and were classified according to the degree of soil lability. The results show that in the canga environment, there was a predominance of inorganic fractions of moderate lability and moderate stability, with a strong dependency of the soil organic matter (SOM) on the P fractions, whereas there was a greater participation of the moderately labile organic fractions in the forest than in the canga. On the other hand, in the rehabilitation areas, there was an increase in the labile organic and inorganic fractions as the rehabilitation process advanced. The distribution of P in areas undergoing rehabilitation indicates that there is a tendency for P levels to resemble those of native environments, such as the forests.