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Research Article
Iron islands in the Amazon: investigating plant beta diversity of canga outcrops
expand article infoCaroline Oliveira Andrino§, Rafael Gomes Barbosa-Silva§, Juliana Lovo§, Pedro Lage Viana§, Marcelo Freire Moro|, Daniela Cristina Zappi§
‡ Instituto Tecnológico Vale, Belém, Brazil
§ Museu Paraense Emílio Goeldi, Belém, Brazil
| Universidade Federal do Ceará, Fortaleza, Brazil
Open Access

Abstract

The world’s largest mineral iron province, Serra dos Carajás, is home to an open vegetation known as canga, found on top of isolated outcrops rising out of the Amazon rainforest. Over one thousand vascular plants species have been recorded in these canga sites, including 38 edaphic endemics. A new survey adds to our investigation of biogeographic relationships between sixteen canga outcrops and the effect of the distance between site pairs on the number of shared species, regional species turnover and species distribution patterns. Plant collecting expeditions to the westernmost site, the Serra de Campos of São Félix do Xingu (SFX), were carried out followed by the identification of all collected specimens and the creation of a species database, built to perform biogeographical analyses. Floristic relationships among the sites were investigated regarding their similarity, using multivariate analyses. The correlation between canga areas and species richness was tested, as well as the geographical distance between pairs of outcrops and their shared species. Vascular plants at SFX total 254 species including 17 edaphic endemics. All canga sites are grouped with 25% of minimum similarity, and the SFX falls within a large subgroup of outcrops. The total species number shared between site pairs does not change significantly with geographical distance but is positively correlated with the area of each outcrop. Meanwhile, shared endemic species numbers between site pairs decline when geographical distance increases, possibly imposed by the barrier of the rainforest. Our data suggest higher shared similarity between the largest and species-richest sites as opposed to geographically nearby sites, and provide useful insight for drafting conservation and compensation measures for canga locations. The size of the canga outcrops is associated to higher floristic diversity but connectivity among islands also plays a role in their similarity.

Keywords

campo rupestre, edaphic endemism, island-like habitats, Neotropical mountains, plant species diversity, rainforest, vascular plant survey

Introduction

Mountaintops are often compared to sky-islands, as their vegetation is often distinct from the surrounding lowlands (Alves and Kolbek 2010; Barres et al. 2019). Montane habitats have been scrutinized due to their high species richness and complexity (Särkinen et al. 2012; Antonelli 2015; Kok et al. 2017), arousing scientific interest and have been featured since the first biogeographic studies (Humboldt 1805). In the Amazonian context, open vegetation predominates on exposed rocky surfaces on mountaintops, as opposed to the surrounding lowland rainforest. This vegetation may occur on isolated granite and gneiss inselbergs and quartzitic tepuis, usually above 900 m a.s.l. (Prance 1996; Riina et al. 2019), or over iron-ore conglomerates in the campo rupestre on canga (CRC), found between 600 and 800 m a.s.l. (Viana et al. 2016; Mota et al. 2018; Zappi et al. 2019). There are also island-like lowland ecosystems, such as white sand campinaranas, savannas, and low elevation granitic domes or inselbergs, associated with arenitic and often waterlogged soil in the Amazon region (Gröger and Huber 2007; Adeney et al. 2016; Costa et al. 2019; Henneron et al. 2019; Devecchi et al. 2020).

Canga is the lateritic duricrust that covers a supergene iron ore, with poorly developed soil and moderately hard rocks that are very resistant to erosion and permeable (Gagen et al. 2019). The iron-rich canga presents a series of restrictions to plant establishment, including shallow and rocky soils, high insolation levels, elevated temperatures at ground level, extreme water regime – waterlogged soil alternating with up to five months of drought, added to the presence of metals at potentially toxic concentrations (Schettini et al. 2018). The vegetation in the canga has specific strategies to survive in these stressful edaphic conditions (Gagen et al. 2019), and these conditions have favoured the diversification of edaphic endemic species that are exclusive to the CRC associated with the iron-rich substrate (Giulietti et al. 2019).

Species isolation caused by environmental conditions contrasting with the surrounding forests and associated with the mosaic of different geomorphological situations in the canga creates also an abundance of micro-habitats (Jacobi et al. 2007; Mota et al. 2015; Silva et al. 2020). It is known that such micro-habitats may be linked to multiple speciation events, and the occurrence of endemism (Bonatelli et al. 2014; Leal et al. 2016; Fiorini et al. 2019; Perrigo et al. 2019; Mota et al. 2020).

The first botanical studies on the iron islands of the Serra dos Carajás began in the late 1960s. However, the floristic knowledge was not synthetized and organized until the Flora of the canga of the Serra de Carajás (FCC) project was completed in 2018 (Viana et al. 2016; Mota et al. 2018). This recent flora increased the number of recorded species to 1042 vascular plants (Mota et al. 2018; Salino et al. 2018), and a number of species were confirmed as endemic to the local canga habitat, with 38 species occurring exclusively on this substrate in an area of occupancy of less than 150 km2 (Giulietti et al. 2019). In terms of phytophysiognomies, three major groups were defined by Mota et al. (2015) for Carajás: canga vegetation (scrub, bare slab, nodular canga and low forest grove), hydromorphic vegetation (bogs, temporary lagoons, permanent lakes, temporary streams, buriti palm lakes, swampy forest) and other associated forests (mostly at the edge of canga outcrops).

Due to historic reasons, collection efforts of the FCC project prioritized some areas of canga, while others still lack in-depth studies. For instance, a research in the canga of the Serra Arqueada (SA) in the municipality of Ourilândia do Norte has recently been completed (Fonseca-da-Silva et al. 2020), while the outcrops located within the recently created Parque Nacional dos Campos Ferruginosos (PNCF) are still in need of further investigation (Zappi et al. 2019). Giulietti et al. (2019) mentioned the existence of an interesting, isolated area of canga located c. 160 km southwest of the area studied by the FCC known as Serra de Campos, in the municipality of São Félix do Xingu (SFX).

This study aims to investigate plant distribution and biogeographical patterns that connect the island-like habitats of canga outcrops isolated within an Amazonian rainforest matrix. We evaluated species distribution in the different sites in order to observe whether canga vegetation has elevated levels of beta diversity and whether the flora of each outcrop will be more dissimilar to other outcrops as the geographical distance increases. We provided the first checklist of vascular plants growing on canga at the Serra de Campos of São Félix do Xingu (SFX), to add to the dataset we built to investigate the floristic relationship between canga areas, aiming to improve our understanding of the rich and diverse flora of the region.

Methods

Characterization of the overall study area

The CRC are found in the region of Carajás, located in the southeast part the State of Pará (Viana et al. 2016; Zappi et al. 2019), one of the largest mineral provinces in the world (Ab’saber 1986). At the Serra dos Carajás, the CRC appears atop a series of outcrops that form discontinuous island-like habitats of open, shrubby or grassy vegetation within a dense matrix of rainforest in the southeastern Amazon basin (Mota et al. 2018).

Most of the ferruginous island complex in the southeastern Amazon is within areas protected at different levels. The Serra Norte (SN1, SN2, SN3, SN4, SN5, SN6, SN7, SN8), the Serra Sul (S11A, S11B, S11C S11D) are located in the Floresta Nacional de Carajás, which is an area of sustainable use and thus subject to anthropogenic pressures, and iron ore mining currently occurs in areas SN4, SN5 and S11D. The Serra da Bocaina and Serra do Tarzan are the only fully protected areas, and are both inserted within the Parque Nacional dos Campos Ferruginosos (PNCF). However, the Serra Arqueada and Serra de Campos of São Félix do Xingu have no legal protection.

Floristic list of Serra de Campos

The Serra de Campos (SFX) is a canga outcrop found in the municipality of São Félix do Xingu, southeastern Pará state, Brazilian Amazon. It represents the westernmost limit of the Serra dos Carajás, a complex of ferruginous highland outcrops that extends eastwards to the Municipality of Curionópolis, totalling 126 km2. The plateaus previously studied in the scope of the FCC project (Viana et al. 2016) are found in the Municipalities of Parauapebas (Serra Norte – SN1 to SN8), and Canaã dos Carajás (Serra Sul – S11, Serra do Tarzan – ST and Serra da Bocaina – SB). The SFX comprises two plateaus measuring c. 9 km2, distant about 1 km from each other, known as SFX1 and SFX2 (Fig. 1). The largest of the two plateaus, known as SFX2, extends for 8.5 km and covers an area of 7.6 km2, while SFX1 is 2.5 km long, measuring 1.4 km2. The plateaus are located at 6°23'41"S, 51°52'25"W, with altitudes ranging from 580 to 730 m. a.s.l. (Fig. 1). Distant about 80 km west from SA, the SFX can be accessed through the Municipality of São Felix do Xingu first by crossing the Rio Fresco then taking a road that goes through farmland, leading, after a steep climb, to the canga plateaus.

Figure 1. 

a Geographic location of the present study site at SFX and the other study areas from Carajás complex b aerial view of an island of canga vegetation surrounding by the rainforest (Photo: Leonardo Vianna) c Serra de Campos of São Félix do Xingu (SFX) phytophysiognomy with shrubby and grassy vegetation.

Botanical specimens from SFX deposited in herbaria prior to this study were located through an online search at the Herbarium of the Museu Paraense Emílio Goeldi (MG) and Herbário Ezechias Paulo Heringer (HEPH) (acronyms according to Thiers, continuously updated). Prior to our expeditions, specimens at MG were collected in the 1990´s by João Batista Fernandes da Silva and include the type of Mimosa dasilvae A.S.L. Silva & Secco and several gatherings of Orchidaceae, while HEPH currently holds collections made by Annajulia Elizabeth Heringer Salles and J.B.F. Silva in 2001. All materials available in these collections were analyzed and included in this study.

Four plant collecting expeditions were carried out between 2016 and 2019 (May 2016, April 2017, March 2018, October 2019), aiming to collect fertile material of all vascular species. Collecting method followed Filgueiras et al. (1994) with random walks covering the accessible parts of both plateaus, attempting to stop every 1 km to sample the vegetation and collect fertile specimens. We aimed to visit diverse vegetation types, including open canga slabs, nodular canga, canga scrub, palm swamps (buritizais) and temporary lagoons (Mota et al. 2015)

The samples collected were identified to species by comparing their macroscopic and microscopic morphological features with available bibliography, against herbarium collections (physically and on-line) and also consulting key family specialists. Voucher specimens were deposited at MG. Only one collection number per taxon is cited in the present floristic list. A full specimen list is provided in supplement S1. Species names follow Flora do Brasil online (Flora do Brasil under construction), family delimitation followed APG IV (Angiosperm Phylogeny Group 2016) and author abbreviations follow IPNI (2019).

Database of the distribution of the flora of Serra dos Carajás

Seed plant species distribution data were assembled from the FCC project (Mota et al. 2018), with the compilation of a database comprising 3228 occurrences of 823 species (Zappi et al. 2019). The updates included 23 recent new occurrences for SN1, SN4, SN5, SN7, S11D, and the Serra da Bocaina based on recently collected herbarium material; 149 species for SA (Fonseca-da-Silva et al. 2020); and the newly prepared dataset of SFX. The assembled database comprises 909 seed plant species recorded in CRC at the Carajás complex, including 16 sites (SN1, SN2, SN3, SN4, SN5, SN6, SN7, SN8, S11A, S11B, S11C, S11D, ST, SB, SA and SFX). For the purpose of our analyses, exotic, invasive and weedy species were removed from the dataset as identified in (Giulietti et al. 2018), resulting in 893 species analysed. The code assigned for each site is found in Table 2.

Biogeographical analyses of the flora of canga sites in the Carajás complex

To perform the biogeographical analysis of the CRC of the Carajás complex, the species database was used to investigate the floristic similarity and shared endemicity between different mountaintops across canga sites. Invasive exotic species recorded in each site were excluded from this analysis, as well as specimens with imprecise identification, Lycophytes, and Monilophytes. Floristic similarity between sites was calculated using a presence-absence Matrix (S2, Suppl. material 1) to perform multivariate analysis using ordination and group multivariate methods using the Vegan package in R (Oksanen et al. 2010). We constructed a matrix showing the presence of each species in each site and subjected it to ordination and grouping analyses using a Non-metric Multidimensional Scaling (NMDS) and Unweighted Pair Group Method with Arithmetic mean (UPGMA), respectively. Both analyses used Sorensen (Bray-Curtis) index (Legendre and Legendre 2012) to reflect beta diversity between sites.

To investigate the floristic richness of sites in relation to the size of each outcrop we used the species count for each canga outcrop and, employing GIS, we calculated the area of each outcrop in square kilometres. A linear model of the recorded richness versus area of each outcrop using the ‘glm’ function with Gaussian model was prepared in R. Because the outcrops were subjected to a large collecting effort during the ‘Flora of Carajás’ Project, we assumed that they were adequately sampled. We also evaluated whether the total number of species and of endemic species shared between sites were significantly related with the geographical distance between them. We computed the centroid of each outcrop using GIS and calculated the geographical distance between the centroids of all outcrop pairs. We tested the normality of the residuals of the models with the Shapiro-Wilk test to see whether the residuals significantly departed from normality. If these did not significantly differ from normality, we accepted the p value of the model. If the residuals differed from normality, we analysed the data using non parametric Spearman’s correlation to evaluate if the correlation was significant.

Results

Plant species in canga vegetation at Serra de Campos

This study recorded a total of 254 species, of which 248 are seed plants, five ferns and one lycophyte in the SFX (Table 1). The richest families recorded are Fabaceae (22 species), Poaceae (21 spp.), Cyperaceae (15 spp.), Orchidaceae (12 spp.) and Rubiaceae (12 spp.). The five richest genera are Mimosa (Fabaceae), with 5 species, Cyperus and Rhynchospora (Cyperaceae), with 4 species each, and Borreria (Rubiaceae) and Aechmea (Bromeliaceae), with 3 species each. Thirty-seven species are new records for the CRC of the Carajás complex. From these new records, seven belong to the family Orchidaceae, five are new records of Fabaceae, three Annonaceae, and three Sapindaceae. A yet undescribed species of Lauraceae was found in SFX, belonging to the genus Dicypellium (Dicypellium aff. caryophyllaceum (Mart.) Nees – PLV 6100, Table 1; Fig. 2).

Table 1.

Vascular plant species from Serra de Campos of São Félix do Xingu (SFX), discriminated by novelties for Flora of the canga of Carajás according to Mota et al. (2018) and Fonseca-da-Silva et al. (2020) endemism in canga outcrops according to Giulietti et al. (2019); endemism in Serra de Campos, and life form and voucher information for each species. Collectors: AHS: Anajulia Heringer Salles; BF: Bruno Fernandes Falcão; COA: Caroline Oliveira Andrino; DCZ: Daniela Cristina Zappi; JBFS: João Batista da Silva; MN: Matheus Nogueira; MP: Mayara Pastore; PLV: Pedro Lage Viana. *Invasive exotic species.

Taxa New for Carajás Flora Endemic canga Endemic SFX Life form Voucher
Lycophyte
Selaginellaceae
Selaginella radiata (Aubl.) Spring. Herb DCZ 4055
Monilophytes
Dennstaedtiaceae
Pteridium arachnoideum (Kauf.) Maxon Herb DCZ 4002
Polypodiaceae
Microgramma persicariifolia (Schrad.) C.Presl Herb DCZ 4066
Pleopeltis polypodioides (L.) Andrews & Windham Herb DCZ 3922
Serpocaulon triseriale (Sw.) A.R.Sm. Herb DCZ 4037
Pteridaceae
Doryopteris collina (Raddi) J.Sm. Herb DCZ 4040
Spermathophytes
Acanthaceae
Justicia birae A.S.Reis, F.A.Silva, A.Gil & Kameyama Herb MP 600
Alismataceae
Helanthium tenellum (Mart. ex Schult & Schult.f.) Britton Herb MP 613
Limnocharis flava (L.) Buchenau X Herb PLV 6149
Anacardiaceae
Anacardium occidentale L. Treelet DCZ 3923
Spondias mombin L. X Treelet DCZ 3921
Annonaceae
Annona sericea Dunal X Shrub DCZ 4051
Annona exsucca DC. Tree COA 658
Guatteria procera R.E.Fr. X Tree DCZ 4050
Xylopia aromatica (Lam.) Mart. Treelet DCZ 3970
Apocynaceae
Himatanthus cf. articulatus (Vahl) Woodson Tree COA 676
Mandevilla scabra (Hoffmanns. ex Roem. & Schult.) K. Schum. Liana DCZ 3880
Mandevilla tenuifolia (J.C. Mikan) Woodson Herb DCZ 3885
Matelea microphylla Morillo X Herb DCZ 3942
Tabernaemontana flavicans Willd. ex Roem. & Schult. Treelet COA 613
Tabernaemontana macrocalyx Müll. Arg. Treelet COA 605
Araceae
Anthurium gracile (Rudge) Lindl. Herb DCZ 5017
Anthurium sp.1 X Herb DCZ 3898
Arecaceae
Mauritia flexuosa Mart. Palm DCZ 3961
Mauritiella armata (Mart.) Burret Palm DCZ 3960
Oenocarpus distichus Mart. Palm DCZ 3948
Syagrus cocoides Mart. Palm DCZ 3892
Asteraceae
Emilia fosbergii Nicolson Herb DCZ 4046
Ichthyothere terminalis (Spreng.) S.F. Blake Shrub DCZ 3868
Monogereion carajensis G.M. Barroso & R.M. King X Herb DCZ 3861
Riencourtia pedunculosa (Rich.) Pruski Herb DCZ 3924
Tilesia baccata (L.f.) Pruski Herb DCZ 3980
Unxia camphorata L.f. Herb DCZ 3941
Begoniaceae
Begonia humilis Dryand Herb DCZ 3973
Bignoniaceae
Adenocalymma schomburgkii (DC.) L.G.Lohmann Liana COA 611
Amphilophium mansoanum (DC.) L.G.Lohmann Liana DCZ 4025
Anemopaegma carajasense A.H. Gentry ex Firetti-Leggieri & L.G. Lohmann X Shrub DCZ 3914
Anemopaegma longipetiolatum Sprague Liana DCZ 3867
Jacaranda ulei Bureau & K.Schum. Shrub DCZ 3945
Pachyptera incarnata (Aubl.) Francisco & L.G. Lohmann Liana DCZ 4061
Pleonotoma melioides (S.Moore) A.H.Gentry Liana COA 638
Pleonotoma orientalis Sandwith Liana DCZ 3883
Bixaceae
Cochlospermum orinocense (Kunth) Steud. Treelet DCZ 3875
Boraginaceae
Cordia nodosa Lam. Tree COA 641
Bromeliaceae
Aechmea castelnavii Baker Herb COA 670
Aechmea mertensii (G.Mey.) Schult. & Schult.f. Herb COA 673
Aechmea tocantina Baker Herb AHS 2194
Ananas ananassoides (Baker) L.B. Sm. Herb DCZ 3891
Dyckia duckei L.B.Sm. Herb DCZ 3872
Tillandsia adpressiflora Mez X Herb DCZ 4034
Burmanniaceae
Burmannia capitata (Walter ex J.F.Gmel.) Mart. Herb MP 644
Burmannia flava Mart. Herb DCZ 3903
Cabombaceae
Cabomba furcata Schult. & Schult.f. Herb DCZ 3963
Commelinaceae
Commelina erecta L. Herb DCZ 4058
Dichorisandra hexandra (Aubl.) C.B. Clarke Liana DCZ 3858
Connaraceae
Rourea ligulata Baker Shrub COA 666
Convolvulaceae
Distimake macrocalyx (Ruiz & Pav.) A.R. Simões & Staples X Liana MP 660
Ipomoea decora Meisn. Liana DCZ 4057
Ipomoea marabaensis D.F.Austin & Secco Liana DCZ 3873
Ipomoea rubens Choisy X Liana MP 672
Cucurbitaceae
Gurania sinuata (Benth.) Cogn. Herb AHS 2167
Cyperaceae
Bulbostylis conifera (Kunth) C.B. Clarke Herb COA 624
Cyperus aggregatus (Willd.) Endl. Herb DCZ 3865
Cyperus laxus Lam. Herb DCZ 3957
Cyperus sesquiflorus (Torr.) Mattf. & Kük. Herb DCZ 4031
Cyperus sphacelatus Rottb. Herb DCZ 4042
Diplasia karatifolia Rich. in Pers. X Herb DCZ 4032
Eleocharis flavescens (Poir.) Urb. Herb MP 627
Eleocharis pedrovianae C.S. Nunes, R. Trevis. & A. Gil X Herb DCZ 4027
Eleocharis plicarhachis (Griseb.) Svenson Herb COA 678
Rhynchospora barbata (Vahl) Kunth Herb COA 657
Rhynchospora filiformis Vahl Herb DCZ 3930
Rhynchospora holoschoenoides (Rich.) Herter Herb MP 608
Rhynchospora seccoi C.S.Nunes, P.J.S. Silva Filho & A.Gil Herb DCZ 3905
Scleria cyperina Willd. ex Kunth Herb DCZ 3925
Scleria microcarpa Nees ex Kunth Herb COA 650
Dioscoreaceae
Dioscorea piperifolia Humb. & Bonpl. ex Willd. Liana DCZ 3884
Dioscorea trilinguis Griseb. X Liana DCZ 3934
Eriocaulaceae
Eriocaulon carajense Moldenke X Herb DCZ 3936
Eriocaulon cinereum R.Br. Herb DCZ 4049
Paepalanthus fasciculoides Hensold Herb DCZ 3878
Syngonanthus discretifolius (Moldenke) M.T.C. Watanabe X Herb PLV 6119
Syngonanthus heteropeplus (Körn.) Ruhland Herb MP 659
Erythroxylaceae
Erythroxylum nelson-rosae Plowman X Shrub COA 672
Erythroxylum rufum Cav. Shrub COA 637
Euphorbiaceae
Alchornea discolor Poeppig Shrub DCZ 3886
Aparisthmium cordatum (A. Juss.) Baill. Tree DCZ 3997
Astraea lobata (L.) Klotzsch Shrub DCZ 3955
Mabea angustifolia Spruce ex Benth. Shrub DCZ 3987
Manihot quinquepartita Huber ex D.J.Rogers Shrub DCZ 3954
Manihot tristis Müll.Arg. Shrub MP 666
Maprounea brasiliensis A.St.-Hil. X Shrub DCZ 3991
Fabaceae
Abrus melanospermus Hassk. Liana DCZ 3912
Aeschynomene sensistiva var. hispidula (Kunth) Rudd Subshrub DCZ 4024
Bauhinia pulchella Benth. Shrub DCZ 3869
Camptosema ellipticum (Desv.) Burkart Shrub DCZ 3907
Centrosema carajasense Cavalcante Herb/Liana DCZ 4007
Chamaecrista desvauxii (Collad.) Killip Subshrub DCZ 3946
Clitoria falcata Lam. Liana DCZ 3917
Crotalaria maypurensis Kunth Shrub DCZ 3881
Dioclea apurensis Kunth Liana DCZ 3919
Inga calantha Ducke X Tree COA 600
Inga heterophylla Willd X Tree DCZ 4036
Inga leiocalycina Benth. X Tree MP 598
Mimosa dasilvae A.S.L. Silva & Secco X X X Subshrub COA 622
Mimosa guilandinae var. spruceana (Benth.) Barneby Shrub COA 668
Mimosa skinneri Benth. var. carajarum Barneby X Herb DCZ 3860
Mimosa somnians Humb. & Bonpl. ex Willd. Subshrub DCZ 3876
Mimosa xanthocentra Mart. Tree PLV 6158
Parkia platycephala Benth. Shrub DCZ 4013
Periandra mediterranea (Vell.) Taub. Shrub DCZ 3902
Senegalia multipinnata (Ducke) Seigler & Ebinger Treelet COA 603
Stylosanthes capitata Vogel Subshrub DCZ 3977
Tachigali vulgaris L.F.G.Silva & H.C.Lima Tree COA 655
Gentianaceae
Schultesia benthamiana Klotzsch ex Griseb. Herb DCZ 3928
Heliconiaceae
Heliconia psittacorum L.f. X Herb MP 671
Hypericaceae
Vismia gracilis Hieron Treelet COA 654
Iridaceae
Cipura xanthomelas Maxim. ex Klatt Herb DCZ 3899
Lamiaceae
Amasonia lasiocaulos Mart. & Schau ex Schau. Subshrub DCZ 3947
Hyptis atrorubens Poit. Herb DCZ 3981
Mesosphaerum pectinatum (L.) Kuntze Herb MN 697
Mesosphaerum suaveolens (L.) Kuntze Herb DCZ 4048
Vitex panshiniana Moldenke X Tree DCZ 4053
Lauraceae
Cassytha filiformis L. Parasite DCZ 3874
Dicypellium aff. caryophyllaceum (Mart.) Nees X X Shrub PLV 6100
Mezilaurus itauba (Meisn.) Taub. ex Mez Shrub DCZ 4001
Rhodostemonodaphne praeclara (Sandwith) Madriñán X Tree DCZ 3983
Lentibulariaceae
Utricularia neottioides A.St-Hil & Girard Herb MP 664
Utricularia pusilla Vahl Herb DCZ 3904
Utricularia subulata L. Herb PLV 6139
Loranthaceae
Passovia pedunculata (Jacq.) Kuijt Parasite DCZ 3909
Psittacanthus eucalyptifolius (Kunth) G. Don Parasite DCZ 4056
Lythraceae
Cuphea annulata Koehne Subshrub DCZ 3864
Cuphea carajasensis Lourteig X Shrub COA 616
Malpighiaceae
Banisteriopsis malifolia (Nees & Mart.) B.Gates Shrub MN 743
Banisteriopsis stellaris (Griseb.) B.Gates Liana DCZ 3863
Byrsonima chrysophylla Kunth Shrub DCZ 3929
Heteropterys nervosa A.Juss. Liana COA 645
Malvaceae
Waltheria indica L. X Shrub DCZ 4064
Marantaceae
Monotagma plurispicatum (Körn.) K.Schum. Herb DCZ 4000
Marcgraviaceae
Norantea guianensis Aubl. Shrub DCZ 3887
Melastomataceae
Bellucia grossularioides (L.) Triana X Shrub DCZ 3995
Brasilianthus carajensis Almeda & Michelangeli Herb DCZ 3877
Clidemia capitellata (Bonpl.) D.Don Shrub DCZ 4020
Miconia alternans Naudin Shrub DCZ 4021
Miconia heliotropoides Triana Shrub DCZ 4008
Nepsera aquatica (Aubl.) Naudin Herb COA 649
Pleroma carajasense K.Rocha, R.Goldenb. & F.S.Mey X Shrub DCZ 3910
Pterolepis trichotoma (Rottb.) Cogn. Herb DCZ 4019
Tibouchina edmundoi Brade Shrub DCZ 3932
Menispermaceae
Abuta grandifolia (Mart.) Sandwith Shrub COA 646
Cissampelos andromorpha DC. . Liana COA 663
Metteniusaceae
Emmotum nitens (Benth.) Miers Shrub MP 601
Myrtaceae
Eugenia punicifolia (Kunth) DC. Shrub DCZ 3894
Myrcia cuprea (O.Berg.) Kiaersk. Shrub COA 639
Myrcia splendens (Sw.) DC. Shrub DCZ 3965
Myrciaria floribunda (H.West ex Willd.) O.Berg Shrub DCZ 3915
Myrciaria glomerata O.Berg X Shrub DCZ 4010
Ochnaceae
Ouratea castaneifolia (DC.) Engl. Treelet DCZ 3920
Ouratea cearensis (Tiegh.) Sastre & Offroy X Shrub COA 604
Ouratea racemiformis Ule Shrub DCZ 4033
Onagraceae
Ludwigia cf. latifolia (Benth.) H.Hara X Subshrub DCZ 3967
Ludwigia nervosa (Poir.) H.Hara Shrub COA 674
Orchidaceae
Catasetum boyi Mansf. X Herb JBFS 648
Catasetum discolor (Lindl.) Lindl. Herb DCZ 4030
Cyrtopodium andersonii (Lamb. ex Andrews) R.Br. Herb COA 643
Encyclia chloroleuca (Hook.) Neum. X Herb JBFS 540
Epidendrum strobiliferum Rchb.f. X Herb COA 667
Erycina pusilla (L.) N.H.Williams & M.W.Chase Herb JBFS 498
Habenaria nuda Lindl Herb MP 609
Habenaria orchiocalcar Hoehne X Herb JBFS 219
Polystachya concreta (Jacq.) Garay & H.R.Sweet Herb COA 669
Rodriguezia lanceolata Ruiz & Pav. X Herb COA 665
Scaphyglottis cf. livida Herb COA 671
Sobralia liliastrum Salzm. ex Lindl. Herb DCZ 3888
Orobanchaceae
Buchnera carajasensis Scatigna & N.Mota X Herb DCZ 3931
Passifloraceae
Passiflora ceratocarpa F. Silveira Liana DCZ 4060
Passiflora picturata Ker Gawl. X Liana DCZ 3976
Passiflora tholozanii Sacco Liana COA 612
Phyllanthaceae
Phyllanthus hyssopifolioides Kunth. Herb DCZ 4028
Phyllanthus minutulus Müll.Arg. Herb DCZ 4026
Phytolaccaceae
Phytolacca thyrsiflora Fenzl ex J. Schmidt Herb DCZ 4041
Piperaceae
Peperomia albopilosa D. Monteiro X Herb PLV 6169
Peperomia magnoliifolia (Jacq.) A.Dietr. Herb COA 647
Plantaginaceae
Scoparia dulcis L. Herb DCZ 4065
Poaceae
Acroceras zizanioides (Kunth) Dandy Herb DCZ 4022
Andropogon bicornis L. Herb DCZ 3950
Axonopus cf. longispicus (Döll) Kuhlm. Herb DCZ 4023
Axonopus rupestris Davidse Herb DCZ 3896
Eleusine indica (L.) Gaertn.* Herb DCZ 4045
Hildaea parvispiculata C. Silva & R.P. Oliveira Herb PLV 6124
Ichnanthus calvescens (Nees ex Trin.) Döll Herb DCZ 4011
Luziola peruviana Juss. ex J.F.Gmel. Herb DCZ 3918
Melinis minutiflora P.Beauv.* Herb COA 640
Mesosetum cayennense Steud. Herb PLV 6117
Oryza glumaepatula Steud. Herb BFF 634
Paspalum axillare Swallen Herb PLV 6130
Paspalum foliiforme S.Denham Herb DCZ 3916
Paspalum reticulinerve Renvoize Herb PLV 6166
Rhytachne gonzalezii Davidse Herb PLV 6127
Rugoloa pilosa (Sw.) Zuloaga Herb DCZ 3964
Steinchisma laxum (Sw.) Zuloaga Herb COA 677
Taquara micrantha (Kunth) I.L.C.Oliveira & R.P.Oliveira Herb DCZ 3999
Trachypogon spicatus (L.f.) Kuntze Herb DCZ 3944
Trichanthecium cf. arctum (Swallen) Zuloaga & Morrone Herb DCZ 3913
Urochloa maxima (Jacq.) R.D. Webster* Herb DCZ 3951
Polygalaceae
Bredemeyera divaricata (DC.) J.F.B. Pastore Shrub DCZ 3911
Caamembeca spectabilis (DC.) J.F.B. Pastore Subshrub COA 642
Polygala adenophora DC. Herb DCZ 3900
Portulacaceae
Portulaca sedifolia N.E.Br. Herb DCZ 3862
Primulaceae
Cybianthus detergens Mart. Shrub DCZ 4062
Proteaceae
Roupala montana Aubl. Shrub DCZ 4063
Rhamnaceae
Gouania pyrifolia Reissek X Liana DCZ 3953
Rubiaceae
Alibertia edulis (Rich.) A. Rich. ex DC. Shrub DCZ 4035
Borreria alata (Aubl.) DC. Herb DCZ 3866
Borreria carajasensis E.L. Cabral & L.M. Miguel X Subshrub DCZ 3859
Borreria semiamplexicaulis E.L.Cabral Herb DCZ 3938
Cordiera myrciifolia (K.Schum.) C.H.Perss. & Delprete Shrub DCZ 3971
Coutarea hexandra (Jacq.) K.Schum. X Shrub COA 610
Guettarda argentea Lam. Shrub COA 602
Palicourea guianensis Aubl. Treelet DCZ 4052
Perama carajensis J.H. Kirkbr. X Herb DCZ 3879
Psychotria colorata (Willd. ex Schult.) Mull. Arg. Herb DCZ 4017
Psychotria hoffmannseggiana (Willd. ex Schult.) Mull. Arg. Subshrub COA 601
Sabicea grisea Cham. & Schltdl. Liana DCZ 3901
Rutaceae
Dictyoloma vandellianum A. Juss. Treelet DCZ 3975
Ertela trifolia (L.) Kuntze Subshrub COA 607
Pilocarpus microphyllus Stapf ex Wardlew. Shrub COA 653
Salicaceae
Casearia arborea (Rich.) Urb. Tree DCZ 3982
Casearia javitensis Kunth Shrub DCZ 4014
Sapindaceae
Allophylus semidentatus (Miq.) Radlk. X Shrub DCZ 3959
Paullinia stellata Radlk. X Liana DCZ 4044
Pseudima frutescens (Aubl.) Radlk. X Shrub PLV 6151
Serjania lethalis A.St.-Hil. Liana DCZ 3996
Sapotaceae
Pouteria ramiflora (Mart.) Radlk. Treelet DCZ 3969
Simaroubaceae
Simaba guianensis Aubl. Shrub DCZ 3984
Simarouba amara Aubl. Shrub DCZ 3985
Siparunaceae
Siparuna ficoides S.S.Rener & Hausner Treelet COA 660
Smilacaceae
Smilax irrorata Mart. ex Griseb Liana DCZ 3935
Solanaceae
Solanum americanum Mill. Herb DCZ 4059
Solanum crinitum Lam. Treelet COA 623
Trigoniaceae
Trigonia nivea Cambess. Liana COA 651
Turneraceae
Turnera glaziovii Urb Shrub DCZ 4012
Turnera laciniata Arbo Herb DCZ 3993
Turnera melochioides Cambess. Shrub PLV 6160
Urticaceae
Cecropia palmata Willd. Tree COA 664
Velloziaceae
Vellozia glauca Pohl Herb DCZ 3890
Verbenaceae
Lantana trifolia L. X Shrub MN 755
Lippia grata Schauer Shrub DCZ 3871
Stachytarpheta cayennensis (Rich.) Vahl Subshrub COA 608
Vitaceae
Cissus erosa Rich. Liana DCZ 3882
Vochysiaceae
Qualea parviflora Mart. Tree MP 624
Xyridaceae
Xyris brachysepala Kral X Herb PLV 6125
SPECIES TOTAL (254) 36 17 2
Figure 2. 

Representative species of canga in new dataset, SFX a Axonopus longispicus (Döll) Kuhlm b Dicypellium aff. caryophyllaceum (Mart.) Nees c Inga heterophylla Willd d Ipomoea decora Meisn e Matelea microphylla Morillo f Mimosa dasilvae A.S.L. Silva & Secco g Nepsera aquatica (Aubl.) Naudin h Ouratea cearensis (Tiegh.) Sastre & Offroy i Pachyptera incarnata (Aubl.) Francisco & L.G. Lohmann j Passifora picturata Ker Gawl. k Phyllanthus minutulus Mull.Arg. l Rodriguezia lanceolata Ruiz & Pav.

Among the 38 edaphic endemic species of canga, defined according to Giulietti et al. (2019), 17 (c. 50%) were recorded in SFX. Two of these, Erythroxylum nelson-rosae Plowman (Erythroxylaceae) and Matelea microphylla Morillo (Apocynaceae) were not previously recorded for SFX in the list of endemic edaphic species of the canga of Carajás (Giulietti et al. 2019). One species, Mimosa dasilvae (Fabaceae), is only known to occur in SFX.

Table 2.

Areas compared by this study, respective area codes used in the multivariate analysis and number of angiosperms species recorded for each area. Serra de Campos of São Félix do Xingu (SFX) data is produced by this study, ARQ-CAN data is available in Fonseca-da-Silva et al. (2020) and Flora of the canga of the Serra de Carajás (FCC) data is available in Mota et al. (2018).

Area code Area Species Cumulative species
ARQ Serra Arqueada 149 149
S11A Serra dos Carajás – Serra Sul 11A 230 535
S11B Serra dos Carajás – Serra Sul 11B 201
S11C Serra dos Carajás – Serra Sul 11C 180
S11D Serra dos Carajás – Serra Sul 11D 428
SN1 Serra dos Carajás – Serra Norte 1 383 643
SN2 Serra dos Carajás – Serra Norte 2 125
SN3 Serra dos Carajás – Serra Norte 3 218
SN4 Serra dos Carajás – Serra Norte 4 308
SN5 Serra dos Carajás – Serra Norte 5 293
SN6 Serra dos Carajás – Serra Norte 6 99
SN7 Serra dos Carajás – Serra Norte 7 112
SN8 Serra dos Carajás – Serra Norte 8 101
SB Serra dos Carajás – Serra da Bocaina 223 336
ST Serra dos Carajás – Serra do Tarzan 211
SFX Serra de Campos – São Félix do Xingu 248 248

Around 25% (60) of the 248 angiosperms registered for SFX are restricted to the Amazonian Rainforest biome, but the majority of the flora is widely distributed in open habitats throughout South America.

The vegetation of the Serra de Campos

Regarding the phytophysiognomies listed by Mota et al. (2015) for the region, the canga vegetation of the SFX has a predominance of vast spreads of scrub composed of closely disposed treelets and shrubs. Amongst them, treelets and shrubs such as Byrsonima chrysophylla Kunth, Cordiera myrciifolia (K.Schum.) C.H.Perss. & Delprete, Anemopaegma carajasense A.H. Gentry ex Firetti-Leggieri & L.G. Lohmann*, Cuphea annulata Koehne, Lippia grata Schauer, Erythroxylum nelson-rosae Plowman*, Syagrus cocoides Mart., as well as several species of Myrcia and Eugenia, the palm Syagrus cocoides Mart. and scramblers and climbers such as Norantea guianensis Aubl., Cissus erosa Rich., Mandevilla scabra (Hoffmanns. ex Roem. & Schult.) K. Schum. and Smilax irrorata Mart. ex Griseb. On more exposed, bare canga slabs, the plants grow mostly in rock crevices with presence of monocots such as Vellozia glauca Pohl, Sobralia liliastrum Salzm. ex Lindl., Dyckia duckei L.B. Sm. and the tuberous, low growing Mandevilla tenuifolia (J.C. Mikan) Woodson, as well as the herbaceous Borreria semiamplexicaulis E.L.Cabral, Perama carajensis J.H.Kirk.*, Begonia humilis Dryand and Brasilianthus carajensis Almeda & Michelangeli*. The nodular canga has more or less continuous covering of grass and sedge, with occasional specimens of Riencourtia pedunculosa (Rich.) Prusky. During the expeditions we did not come across low forest groves, and our impression was that between the canga edge and the surrounding rainforest there was not much transition but a sharp substitution of the open vegetation by the associated forest types. Regarding the hydromorphic vegetation found in SFX, temporary shallow ponds with Utricularia species, Burmannia flava Mart., Cabomba furcata Schult. & Schult. f., Syngonanthus caulescens (Poir.) Ruhland and Xyris brachysepala Kral.* were visited. However, perennial, larger ponds of the magnitude found in the Serra Sul were lacking and temporary streams were not observed. There were also Palm swamps (buritizais), with margins occupied by Mauritia flexuosa Mart. and Mauritiella armata (Mart.) Burret, harbouring aquatic Oryza glumaepatula Steud., Helanthium tenellum (Mart. ex Schult. & Schult.f.) Britton and Eleocharis spp. (edaphic endemic species marked with *).

Database of the flora of Serra dos Carajás complex

The biogeographical database from the CRC of the Carajás complex was updated by our study (see supplementary data) and includes now a total of 893 angiosperms distributed in 121 families and 441 genera. For the Carajás flora (FCC), Poaceae was the most species-rich family (75 species in the FCC), followed by Fabaceae (66 spp.), Cyperaceae (57 spp.), Rubiaceae (49 spp.), and Melastomataceae (40 spp.). The richest genera were Rhynchospora (24 spp.), Miconia (18 spp.), Paspalum and Solanum (17 spp. each), Myrcia and Ipomoea (13 spp. each), while 64% (284 genera) were represented by only a single species. The inclusion of SFX in our database increased the number of known taxa by 18 genera and 37 species not previously recorded for the canga of Carajás.

Biogeography of the Campos Rupestres on Canga of the Carajás complex

The mean angiosperm species richness for each outcrop of the Serra dos Carajás was 218 species. The NMDS and UPGMA analyses included 3451 records of 893 species across 16 sites (Fig. 3a, b). The UPGMA analyses produced statistically significant clusters (Fig. 3b) with the same major groups found by Fonseca-da-Silva et al. (2020), one comprising four of the eight areas of the Serra Norte (SN2, SN6, SN7, and SN8), while the remaining four (SN1, SN3, SN4, and N5) appear closer to the areas of Serra Sul (S11A, S11B. S11C, S11D), along with SB and ST. SA also emerged as the least similar to the Carajás complex, and SFX was found to be more similar to the group comprising SB, ST, Serra Sul and the four most species rich sites in Serra Norte (SN1, SN3, SN4, and SN5). A similar result was obtained by the NMDS analysis (Fig. 3a), also showing SA as the most dissimilar from other areas.

Figure 3. 

UPGMA (a) and NMDS (b) multivariate analysis clustering areas from FCC and SFX (see Table 2 for area codes). UPGMA cophenetic coefficient: 0.902. b. NMDS stress: 0.1859.

Species richness was significantly correlated with site area (r = 0.806094, P = 0.001548). The larger the area of each individual mountaintop (site), the larger the number of species recorded. The total number of shared species between mountaintop outcrops did not differ significantly with geographical distance across sites (r = -0.16; P = 0.08). There was a tendency of distant sites to share less species, but this trend was not significant. When the residuals of this model were evaluated they significantly departed from normality. Spearman’s correlation was not significant either (p-value = 0.2972). However, when focusing on the number of shared endemic edaphic species versus the geographical distance between sites, we found a significant correlation, where closer sites shared more edaphic endemic species than with more distant sites (r = -0.45872; P = 1.37e-07) (Fig. 4).

Figure 4. 

a Species richness plotted against area of Carajás. Pearson correlation coefficients: r = 0.806094, P = 0.001548 b the number of species shared between site pairs does not change significantly with geographical distance between regions. r = -0.16; P = 0.08 c the number of shared endemic species between site pairs declines with geographical distance between regions. r= -0.45872; P = 1.37e-07.

Regarding the total of species of the canga, the Carajás iron islands share an average of 40% of their flora with each other. SFX has, on average, 30% of shared species with each other area. The percentage of similarity between sites was a minimum of 30% and a maximum of 55%.

Discussion

Floristic composition of Serra de Campos × other canga outcrops

The most species-rich families and genera found in the SFX coincide with those found in the Flora das cangas de Carajás (Mota et al. 2018) and SA (Fonseca-da-Silva et al. 2020), where Cyperaceae, Fabaceae, Poaceae, and Rubiaceae are among the richest plant families. Interestingly, SFX has a much higher number of Orchidaceae species than other surveys of canga in the Amazon (Koch et al. 2018; Mota et al. 2018; Fonseca-da-Silva et al. 2020). The participation of botanical specialists during collecting expeditions enhances floristic studies in the Amazon (Medeiros et al. 2014) and elsewhere, and the high number of Orchidaceae in SFX possibly reflects the specific search for this group by J.B. Silva in the region from the 1990’s onwards, which may have resulted in a greater sampling effort for this group when compared to other areas.

There is a large turnover of species between outcrops (Zappi et al. 2019; Fonseca-da-Silva et al. 2020) and very few species are widely distributed across these disjunct, isolated habitats. Similar to what was found by (Costa et al. 2019) in Amazonian White Sand Campinas, the isolation of the patchy canga outcrops limits dispersal and increases floristic differentiation, and the adverse conditions, such as high temperature, extreme exposure to sunlight and winds, and a relatively well defined dry season represent ecological filters for the species that occupy the canga, partly explaining the high number of endemic species in the CRC of Carajás.

As an example, only three species were recorded in all surveyed areas: the widely distributed Riencourtia pedunculosa, an Asteraceae common in open areas in the Amazon (Flora do Brasil under construction, Bringel 2014), and two species associated with Amazonian canga outcrops: Brasilianthus carajensis and Perama carajensis. Perama carajensis is a confirmed canga edaphic endemic species, and Brasilianthus carajensis has been collected also on granite, being locally endemic to Carajás, but not a canga edaphic endemic (Giulietti et al. 2019; Silva et al. 2020). Other four species also present wide occurrence across campos rupestres on canga of Carajás: Bulbostylis conifera (Kunth) C.B. Clarke, Rhynchospora barbata (Vahl) Kunth, Rhynchospora seccoi C.S.Nunes et al., and Syngonanthus discretifolius (Moldenke) M.T.C. Watanabe were recorded for SFX and many other FCC areas, except for one of them missing in SN3, SN7, SN7 and SA, respectively. Their absence in these four sites may be related to the more modest canga surface found in these areas.

Some widely distributed species from the canga of Carajás, found at more than 10 of the 16 sites surveyed, were not recorded at SFX. The absence of the common treelets Callisthene microphylla Warm. and Mimosa acutistipula var. ferrea Barneby (Mota et al. 2015) at SFX may be partially explained by differences in the micro-habitats between SFX and the other canga outcrops considered here. For Brasilianthus carajensis, distinct adaptive genetic clusters have been found in the SFX (see Silva et al. 2020), increasing the argument for the protection of the site.

The canga is typically a mosaic of different vegetation types (Mota et al. 2015, Viana et al. 2016). Some of these vegetation types are infrequent in SFX, as for example low forest groves (Mota et al. 2015), and in consequence some of the species found in these groves elsewhere are absent at SFX: Callisthene microphylla, Mimosa acutistipula var. ferrea, and Cereus hexagonus (L.) Mill. Although forest groves are closely associated with the lower scrub vegetation, the latter is more abundant in the canga plateau of SFX than the former. In plateau SFX2 of SFX the shrubby vegetation is dominant, and there are large stands of Syagrus cocoides Mart., a palm emerging from the impenetrable shrubbery. In the context of CRC of Carajás, this palm forms large populations only in SA and SFX.

Despite having the lowest number of species registered in the FCC, the hydromorphic vegetation found atop the plateaus is the habitat with the highest proportion of exclusive species (Pereira et al. 2016; Mota et al. 2018). Seasonal lakes and palm lakes in the SFX ensure the presence of annual aquatic species such as Eriocaulon carajense Moldenke, Oryza glumaepatula Steud., Syngonanthus caulescens (Poir.) Ruhland, and Xyris brachysepala Kral.

As a relatively large canga site isolated from the active iron mines further to the east, the SFX has been found to harbour a rich and unique vegetation, representing a suitable area for the implementation of conservation strategies. On the other hand, this canga outcrop is currently threatened by surrounding deforestation, land transformation and frequent fires, and is not included within any type of protected area.

Iron islands of Carajás and their floristic connections

The mosaic of landscapes typical of CRC of Carajás may also explain the low floristic similarity between the sites. The number of shared species represents less than half the local richness from each site separately. This brings attention to the high beta diversity among sites (Zappi et al. 2019), with a large species turnover across these disjunct outcrops. Habitat diversity associated with the size of the island-like habitats is also related to the beta diversity in French Guiana´s inselbergs (Henneron et al. 2019), similarly to what is found in Andean alpine flora (Sklenář et al. 2014) and South American tepuis (Riina et al. 2019). This confirms the association between area and habitat diversity found here for the canga vegetation as an important factor for determining plant biodiversity.

The greater similarity between SFX, SB and ST, along with Serra Sul (S11A, S11B, S11C, and S11D) and SN1, SN3, SN4 and SN5 reflected in the UPGMA clustering patterns (Fig. 3b) suggests there is more similarity of species richness between the largest sites rather than among geographically closest areas, as observed by Fonseca-da-Silva et al. (2020) for SA. In fact, the correlation between the shared species of each canga site and their geographical distance was significant. Considering the size of each of these areas and their positive correlation with floristic richness (Fig. 4), we interpret the canga’s overall surface as being more important for floristic composition than the distance between sites in the Serra dos Carajás. Thus, the larger a canga outcrop is, the greater the number of micro-habitats it can harbour, reflecting an increased species richness and unique floristic composition of each canga site. On the other hand, that relationship (distance between areas vs shared flora) holds true when analysing shared endemic species, where shared endemic species decrease with distance at different rates (Fig. 4C).

The low number of species restricted to the Amazon (25%) and the high number of species widely distributed in South America (75%) recorded at SFX, may explain the discrepancy in the correlation between shared species and distance being negative when all species are considered, whereas it is positive for endemic species only. On a macro-scale, the majority of the species recorded in SFX have a broad distribution, occurring beyond the Amazon Rainforest, and the distance factor between different outcrops may not matter so much. On the other hand, when observing only the species endemic to Carajás, and especially edaphic endemic species, the trend is the opposite, possibly due to the local scale of observation, as elsewhere the distance between areas tends to affect the floristic similarity between island vegetations (Sklenář et al. 2014; Schrader et al. 2020). A genomic study revealed that gene flow in two endemic species of Carajás is mainly influenced by geographic distance between mountain pairs, as the rainforest surrounding different mountaintops constitutes an important barrier (Carvalho et al. 2019). Therefore, gene flow also decreases with the increase of the barrier represented by the rainforest (Carvalho et al. 2019).

Another factor that may have an impact on the contrasting effects of floristic similarity vs. distance from canga islands is the different environmental requirements of herbs, shrubs and trees, that shape their biogeographical patterns and affect species-area and richness-environment relationships (Schrader et al. 2020). Herbs, shrubs and trees have contrasting strategies in different environmental conditions with potential implications for community assemblage on islands. For example, herbs can form larger populations on small islands due to their smaller size, and as a result face less risk of extinction and greater dispersal capacity (Moles 2005; Thomson et al. 2010), while shrubs are associated with more stable environmental conditions, and therefore have more success on larger islands (Chiarucci et al. 2017).

Recent analyses of open vegetation in the Amazon reinforce the insular character of Amazonian canga and their low similarity to other vegetation types in the Amazonian biome (Devecchi et al. 2020). While there is some evidence that canga in Southeastern Brazil may be influenced by the surrounding Atlantic Rainforest and Cerrado (Zappi et al. 2017) these biomes are known to have a more varied life-form balance (respectively 1: 4 and 1: 7 proportion of trees over other life forms) than the Amazon Rainforest, where the life form balance is less extreme (1: 2) (Brazil Flora Group [BFG] 2015), thus it may have less floristic influence over the open vegetation found in the CRC of Carajás (Zappi et al. 2019). Therefore, in order to colonize the Amazonian CRC, shrubby or herbaceous plant species may have to come from further afield through long distance dispersal, and, if established, they may remain genetically isolated from their original populations, leading over a period of time to the patterns of endemism observed today.

Table 3.

Species richness of the iron islands outcrops of Carajás complex (bold diagonal) along with the number of shared species (above diagonal) and distance in kilometres (below diagonal) between the centroid sites; an estimated area for each site is provided.

Sites Area (km2) SB ST ARQ S11A S11B S11C S11D SFX SN1 SN2 SN3 SN4 SN5 SN6 SN7 SN8
SB 19.98 221 100 47 79 80 75 135 85 124 46 84 108 101 56 57 56
ST 8.3 24 209 48 88 90 80 138 84 119 59 87 102 105 55 59 53
ARQ 1.27 140 116 149 52 44 45 80 70 75 30 52 77 62 30 29 32
S11A 15.27 59 24 92 228 139 119 170 96 143 59 89 116 101 56 54 53
S11B 8.44 54.6 30.8 82 4.5 199 107 147 77 120 53 81 96 99 49 52 48
S11C 6.26 52.5 28.8 85 10 4.5 177 140 83 110 46 72 101 91 49 41 50
S11D 16.41 47 24.4 92.3 15.7 9.8 5.7 424 141 222 80 134 189 168 75 80 72
SFX 9.04 217 193 79.5 158 162 165 170 239 131 48 82 111 95 52 44 51
SN1 11.81 52 37.7 111 37 38 40 42 180 381 98 154 183 174 77 71 78
SN2 0.86 46.8 32.8 113 36.8 37.1 39.3 40 184 5.18 124 69 73 71 40 34 44
SN3 2.1 44.7 32 117.5 40.2 40.1 42 42.2 188 8.1 3.8 217 129 103 71 60 59
SN4 14.83 38 25 117.4 37.5 36.4 37.7 37 189 13.7 8.6 7.4 305 181 74 65 81
SN5 8.26 32.36 22.75 122 41 39 40 38.53 195 19.78 14.6 12.4 6.2 289 63 54 69
SN6 0.97 35.29 22.46 118 37.3 35.8 36.7 35.7 190 16 11 10 3 4 99 40 42
SN7 0.34 33 19 117 35.7 33.8 34 33.1 190.5 18 14 13 6 5 3 112 46
SN8 2.69 30 17 119 37 34.7 35 33 192 22 17 16 8.8 6 5.7 3.3 100

Different evolutionary processes of the species occurring in CRC may also have led to different floristic composition in the outcrops. Although evolutionary studies involving species of canga in the Brazilian Amazon are just beginning (Zappi et al. 2017), the phylogeography of a species of Gesneriaceae distributed in humid rock formations in the Cerrado reveals its recent expansion into CRC vegetation during the Pleistocene (Fiorini et al. 2020). Recent and rapid radiations have been observed in mountaintops ecosystems (Salerno et al. 2012; Pirie et al. 2016; Vasconcelos et al. 2020) but more phylogenetic and phylogeographic studies are necessary to establish dating for plants species groups found in the CRC in order to understand their diversification and colonization processes.

Table 4.

Endemic edaphic species of the iron islands outcrops of Carajás complex (bold diagonal) along with the number of shared endemic species (above diagonal) and distance in kilometres (below diagonal) between the centroid sites.

Sites SB ST ARQ S11A S11B S11C S11D SFX SN1 SN2 SN3 SN4 SN5 SN6 SN7 SN8
SB 20 15 3 17 15 16 19 11 18 11 15 15 13 11 11 12
ST 24 16 2 14 13 14 15 9 15 9 12 11 11 9 10 10
ARQ 140 116 7 5 4 5 7 5 6 3 4 5 3 2 2 4
S11A 59 24 92 24 17 21 22 14 21 10 16 17 13 11 9 12
S11B 54.6 30.8 82 4.5 18 18 19 10 15 14 14 13 12 10 8 10
S11C 52.5 28.8 85 10 4.5 21 21 13 11 10 15 15 13 10 9 12
S11D 47 24.4 92.3 15.7 9.8 5.7 25 14 21 11 18 19 14 12 12 14
SFX 217 193 79.5 158 162 165 170 17 13 9 13 12 8 9 7 9
SN1 52 37.7 111 37 38 40 42 180 29 15 20 22 19 13 12 16
SN2 46.8 32.8 113 36.8 37.1 39.3 40 184 5.18 16 15 14 14 11 8 12
SN3 44.7 32 117.5 40.2 40.1 42 42.2 188 8.1 3.8 23 20 15 15 12 15
SN4 38 25 117.4 37.5 36.4 37.7 37 189 13.7 8.6 7.4 24 18 14 12 17
SN5 32.36 22.75 122 41 39 40 38.53 195 19.78 14.6 12.4 6.2 20 11 9 15
SN6 35.29 22.46 118 37.3 35.8 36.7 35.7 190 16 11 10 3 4 15 8 10
SN7 33 19 117 35.7 33.8 34 33.1 190.5 18 14 13 6 5 3 14 10
SN8 30 17 119 37 34.7 35 33 192 22 17 16 8.8 6 5.7 3.3 17

Conclusions

This is the most complete study analysing a database of canga outcrop islands in the Amazon thus far. Our data suggest higher shared similarity between largest sites and higher species richness. We show that species richness in these vegetation islands reveals complex biogeographic patterns and relatively high beta diversity. Outcrop size seemed to be more important than geographical proximity between outcrops, and this should be taken into account when drafting conservation and compensation measures for the canga. There are still inaccessible canga outcrops towards the north of the state of Pará that remain unexplored, and their study would certainly yield interesting information to be added to the present findings.

Acknowledgements

We are grateful to the Museu Paraense Emílio Goeldi (MPEG) and Instituto Tecnológico Vale (ITV) for essential infrastructure and support for this project, and to Priscila O. Rosa, from the Herbarium HEPH, for providing specimen images. We also acknowledge the financial support provided by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) for grants for COA and RGBS, and CAPES (JL). DCZ currently holds a research grant from CNPq. Invaluable help was provided by specialist botanists Aline Stadnik, Ana Carolina Mezzonato, Beatriz Gomes, Edgar Afonso, Edley Pessoa, Jovani Pereira, Layla Schneider, Matheus Cota, Mayara Pastore, Paulo Gonella, and Valdir Silva-Junior in specimen naming. We thank Nigel P. Taylor for revising the English. We also thank our colleague Alice Hiura for technical support and Fernando Marino Gomes dos Santos for critical reading.

Data availability statement: All supplementary data can be accessed at figshare repository: https://doi.org/10.6084/m9.figshare.12053487

References

  • Ab’saber AN (1986) Geomorfologia da região. In: Almeida JMG (Ed.) Carajás: desafio político, ecologia e desenvolvimento. CNPq, Brasília, 88–124.
  • Angiosperm Phylogeny Group (2016) An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG IV. Botanical Journal of the Linnean Society 181(1): 1–20. https://doi.org/10.1111/boj.12385
  • Barres L, Batalha-Filho H, Schnadelbach AS, Roque N (2019) Pleistocene climatic changes drove dispersal and isolation of Richterago discoidea (Asteraceae), an endemic plant of campos rupestres in the central and eastern Brazilian sky islands. Botanical Journal of the Linnean Society 189(2): 132–152. https://doi.org/10.1093/botlinnean/boy080
  • Bonatelli IAS, Perez MF, Peterson AT, Taylor NP, Zappi DC, Machado MC, Koch I, Pires AHC, Moraes EM (2014) Interglacial microrefugia and diversification of a cactus species complex: Phylogeography and palaeodistributional reconstructions for Pilosocereus aurisetus and allies. Molecular Ecology 23(12): 3044–3063. https://doi.org/10.1111/mec.12780
  • Bringel JB de AJ (2014) Contribuição ao estudo de Heliantheae (Asteraceae): Revisão taxonômica e filogenia de Riencourtia Cass. Universidade de Brasília.
  • Carvalho CS, Lanes ÉCM, Silva AR, Caldeira CF, Carvalho-Filho N, Gastauer M, Imperatriz-Fonseca VL, Nascimento Júnior W, Oliveira G, Siqueira JO, Viana PL, Jaffé R (2019) Habitat Loss Does Not Always Entail Negative Genetic Consequences. Frontiers in Genetics 10: 1011. https://doi.org/10.3389/fgene.2019.01101
  • Chiarucci A, Fattorini S, Foggi B, Landi S, Lazzaro L, Podani J, Simberloff D (2017) Plant recording across two centuries reveals dramatic changes in species diversity of a Mediterranean archipelago. Scientific Reports 7(1): 5415. https://doi.org/10.1038/s41598-017-05114-5
  • Costa FM, Terra‐Araujo MH, Zartman CE, Cornelius C, Carvalho FA, Hopkins MJG, Viana PL, Prata EMB, Vicentini A (2019) Islands in a green ocean: Spatially structured endemism in Amazonian white‐sand vegetation. Biotropica 52(1): 34–45. https://doi.org/10.1111/btp.12732
  • Devecchi MF, Lovo J, Moro MF, Andrino CO, Barbosa-Silva RG, Viana PL, Giulietti AM, Antar G, Watanabe MTC, Zappi DC (2020) Beyond forests in the Amazon: Biogeography and floristic relationships of the Amazonian savannas. Botanical Journal of the Linnean Society 193(4): 478–503. https://doi.org/10.1093/botlinnean/boaa025
  • Filgueiras TS, Nogueira PE, Brochado AL, Gualla II GF (1994) Caminhamento – um método expedito para levantamentos florísticos qualitativos. Cadernos de Geociências 12: 39–43.
  • Fiorini CF, Miranda MD, Silva-Pereira V, Barbosa AR, Oliveira UD, Kamino LHY, Mota NFDO, Viana PL, Borba EL (2019) The phylogeography of Vellozia auriculata (Velloziaceae) supports low zygotic gene flow and local population persistence in the campo rupestre, a Neotropical OCBIL. Botanical Journal of the Linnean Society 191(3): 381–398. https://doi.org/10.1093/botlinnean/boz051
  • Fiorini CF, Peres EA, da Silva MJ, Araujo AO, Borba EL, Solferini VN (2020) Phylogeography of the specialist plant Mandirola hirsuta (Gesneriaceae) suggests ancient habitat fragmentation due to savanna expansion. Flora 262: 151522. https://doi.org/10.1016/j.flora.2019.151522
  • Fonseca-da-Silva TL, Lovo J, Zappi DC, Moro MF, Leal E da S, Maurity C, Viana PL (2020) Plant species on Amazonian canga habitats of Serra Arqueada: The contribution of an isolated outcrop to the floristic knowledge of the Carajás region, Pará, Brazil. Brazilian Journal of Botany 43(2): 315–330. https://doi.org/10.1007/s40415-020-00608-5
  • Gagen EJ, Levett A, Paz A, Gastauer M, Caldeira CF, Valadares RB da S, Bitencourt JAP, Alves R, Oliveira G, Siqueira JO, Vasconcelos PM, Southam G (2019) Biogeochemical processes in canga ecosystems: Armoring of iron ore against erosion and importance in iron duricrust restoration in Brazil. Ore Geology Reviews 107: 573–586. https://doi.org/10.1016/j.oregeorev.2019.03.013
  • Giulietti AM, Abreu I, Viana PL, Furtini Neto AE, Siqueira JO, Pastore M, Harley R, Mota NFO, Watanabe MTC, Zappi D (2018) Guia das Espécies Invasoras e outras que requerem manejo e controle no S11D, Floresta Nacional de Carajás, Pará. Instituto Tecnológico Vale, Belém, 160 pp.
  • Giulietti AM, Giannini TC, Mota NFO, Watanabe MTC, Viana PL, Pastore M, Silva UCS, Siqueira MF, Pirani JR, Lima HC, Pereira JBS, Brito RM, Harley RM, Siqueira JO, Zappi DC (2019) Edaphic Endemism in the Amazon: Vascular Plants of the canga of Carajás, Brazil. Botanical Review 85(4): 357–383. https://doi.org/10.1007/s12229-019-09214-x
  • Gröger A, Huber O (2007) Rock outcrop habitats in the Venezuelan Guayana lowlands: Their main vegetation types and floristic components. Revista Brasileira de Botanica. Brazilian Journal of Botany 30(4): 599–609. https://doi.org/10.1590/S0100-84042007000400006
  • Henneron L, Sarthou C, de Massary J, Ponge J (2019) Habitat diversity associated to island size and environmental filtering control the species richness of rock‐savanna plants in neotropical inselbergs. Ecography 42(9): 1536–1547. https://doi.org/10.1111/ecog.04482
  • Humboldt A (1805) Essai sur la géographie des plantes: accompagné d’un tableau physique des régions équinoxiales, fondé sur des mesures exécutées, depuis le dixième degré de latitude boréale jusqu’au dixième degré de latitude australe, pendant les années 1799, 1800, 1801, 1802 et 1803 ([Reprod.]) par Al. de Humboldt.: 159. https://doi.org/10.5962/bhl.title.9309
  • Jacobi CM, do Carmo FF, Vincent RC, Stehmann JR (2007) Plant communities on ironstone outcrops: A diverse and endangered Brazilian ecosystem. Biodiversity and Conservation 16(7): 2185–2200. https://doi.org/10.1007/s10531-007-9156-8
  • Koch AK, Miranda JC, Hall CF, Koch AK, Miranda JC, Hall CF (2018) Flora of the canga of the Serra dos Carajás, Pará, Brazil: Orchidaceae. Rodriguésia 69(1): 165–188. https://doi.org/10.1590/2175-7860201869115
  • Kok PJR, Russo VG, Ratz S, Means DB, MacCulloch RD, Lathrop A, Aubret F, Bossuyt F (2017) Evolution in the South American “Lost World”: Insights from multilocus phylogeography of stefanias (Anura, Hemiphractidae, Stefania). Journal of Biogeography 44(1): 170–181. https://doi.org/10.1111/jbi.12860
  • Leal BSS, Palma da Silva C, Pinheiro F (2016) Phylogeographic Studies Depict the Role of Space and Time Scales of Plant Speciation in a Highly Diverse Neotropical Region. Critical Reviews in Plant Sciences 35(4): 215–230. https://doi.org/10.1080/07352689.2016.1254494
  • Legendre P, Legendre L (2012) Numerical Ecology. Elsevier Academic Press, Amsterdam.
  • Medeiros H, Obermuller FA, Daly D, Silveira M, Castro W, Forzza RC (2014) Botanical advances in Southwestern Amazonia: The flora of Acre (Brazil) five years after the first Catalogue. Phytotaxa 177(2): 101. https://doi.org/10.11646/phytotaxa.177.2.2
  • Mota NF de O, Martins FD, Viana PL (2015) Vegetação sobre Sistemas Ferruginosos da Serra dos Carajás. In: Carmo FF, Kamino LHY (Eds) Geossistemas Ferruginosos no Brasil. Instituto Prístino, Belo Horizonte, 289–315.
  • Mota MR, Pinheiro F, Leal BS dos S, Sardelli CH, Wendt T, Palma-Silva C (2020) From micro- to macroevolution: Insights from a Neotropical bromeliad with high population genetic structure adapted to rock outcrops. Heredity. https://doi.org/10.1038/s41437-020-00359-9
  • Mota NF de O, Watanabe MTC, Zappi DC, Hiura AL, Pallos J, Viveiros R, Giulietti AM, Viana PL (2018) Amazon canga: The unique vegetation of Carajás revealed by the list of seed plants. Rodriguésia 69: 1435–1487. https://doi.org/10.1590/2175-7860201869336
  • Oksanen J, Blanchet FG, Friendly M, Kindt R, Legendre P, McGlinn D, Minchin PR, O’Hara RB, Simpson GL, Solymos P, Stevens MHH, Szoecs E, Wagner H (2010) vegan: Community Ecology Package. https://CRAN.R-project.org/package=vegan
  • Pirie MD, Oliver EGH, Mugrabi de Kuppler A, Gehrke B, Le Maitre NC, Kandziora M, Bellstedt DU (2016) The biodiversity hotspot as evolutionary hot-bed: Spectacular radiation of Erica in the Cape Floristic Region. BMC Evolutionary Biology 16(1): 190. https://doi.org/10.1186/s12862-016-0764-3
  • Salerno PE, Ron SR, Señaris JC, Rojas-Runjaic FJM, Noonan BP, Cannatella DC (2012) Ancient tepui summits harbor young rather than old lineages of endemic frogs. Evolution 66(10): 3000–3013. https://doi.org/10.1111/j.1558-5646.2012.01666.x
  • Särkinen T, Pennington RT, Lavin M, Simon MF, Hughes CE (2012) Evolutionary islands in the Andes: persistence and isolation explain high endemism in Andean dry tropical forests: Evolutionary islands in the Andes. Journal of Biogeography 39(5): 884–900. https://doi.org/10.1111/j.1365-2699.2011.02644.x
  • Schettini AT, Leite MGP, Messias MCTB, Gauthier A, Li H, Kozovits AR (2018) Exploring Al, Mn and Fe phytoextraction in 27 ferruginous rocky outcrops plant species. Flora 238: 175–182. https://doi.org/10.1016/j.flora.2017.05.004
  • Schrader J, König C, Triantis KA, Trigas P, Kreft H, Weigelt P (2020) Species-area relationships on small islands differ among plant growth forms. Sandel B (Ed.). Global Ecology and Biogeography 29(5): 814–829. https://doi.org/10.1111/geb.13056
  • Silva AR, Resende-Moreira LC, Carvalho CS, Lanes ECM, Ortiz-Vera MP, Viana PL, Jaffé R (2020) Range-wide neutral and adaptive genetic structure of an endemic herb from Amazonian Savannas. Abdelaziz M (Ed.). AoB PLANTS 12: 1–11. https://doi.org/10.1093/aobpla/plaa003
  • Sklenář P, Hedberg I, Cleef AM (2014) Island biogeography of tropical alpine floras. Gillman LN (Ed). Journal of Biogeography 41: 287–297. https://doi.org/10.1111/jbi.12212
  • Thomson FJ, Moles AT, Auld TD, Ramp D, Ren S, Kingsford RT (2010) Chasing the unknown: predicting seed dispersal mechanisms from plant traits: Predicting plant dispersal mechanisms. Journal of Ecology 98(6): 1310–1318. https://doi.org/10.1111/j.1365-2745.2010.01724.x
  • Vasconcelos TNC, Alcantara S, Andrino CO, Forest F, Reginato M, Simon MF, Pirani JR (2020) Fast diversification through a mosaic of evolutionary histories characterizes the endemic flora of ancient Neotropical mountains. Proceedings. Biological Sciences 287(1923): 20192933. https://doi.org/10.1098/rspb.2019.2933
  • Viana PL, Mota NF de O, Gil A dos SB, Salino A, Zappi DC, Harley RM, Ilkiu-Borges AL, Secco R de S, Almeida TE, Watanabe MTC, dos Santos JUM, Trovó M, Maurity C, Giulietti AM (2016) Flora of the cangas of the Serra dos Carajás, Pará, Brazil: History, study area and methodology. Rodriguésia 67: 1107–1124. https://doi.org/10.1590/2175-7860201667501
  • Zappi DC, Moro MF, Meagher TR, Nic Lughadha E (2017) Plant Biodiversity Drivers in Brazilian Campos Rupestres: Insights from Phylogenetic Structure. Frontiers of Plant Science 8: 2141. https://doi.org/10.3389/fpls.2017.02141
  • Zappi DC, Moro MF, Walker B, Meagher T, Viana PL, Mota NFO, Watanabe MTC, Lughadha EN (2019) Plotting a future for Amazonian canga vegetation in a campo rupestre context. PLoS One 14(8): e0219753. https://doi.org/10.1371/journal.pone.0219753

Supplementary material

Supplementary material 1 

Investigating plant beta diversity of canga outcrops

Caroline Oliveira Andrino, Rafael Gomes Barbosa Silva, Juliana Lovo, Pedro Lage Viana, Marcelo Freire Moro, Daniela Cristina Zappi

Data type: species data

This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0/). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited.
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