Research Article |
Corresponding author: Manuela Gazzoni dos Passos ( biologamanu@gmail.com ) Academic editor: Ana Maria Leal-Zanchet
© 2021 Manuela Gazzoni dos Passos, Geisa Percio do Prado, Claudia Fontana, Edilvane Ines Zonta, Edmilson Bianchini.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Passos MG, Prado GP, Fontana C, Zonta EI, Bianchini E (2021) Natural regeneration in a mixed ombrophilous forest remnant in southern Brazil. Neotropical Biology and Conservation 16(1): 167-183. https://doi.org/10.3897/neotropical.16.e58188
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The study of forest regeneration allows the diagnosis of conservation status of fragments and estimating population parameters that are essential for management projects. This study evaluated the structure, diversity and dynamics of the tree regenerating component of a remnant of mixed ombrophilous forest, aiming to support management actions for this forest type. The study was developed at the Parque Estadual das Araucárias (PEAR), located in the western region of the state of Santa Catarina, southern Brazil. A total of 100 plots of 25 m2 (0.25 ha) were allocated, all individuals with height ≥ 1.0 m and DBH < 5 cm were sampled. Shannon’s diversity index (H’), Pielou’s equability index (J) and total natural regeneration rate (TNR) were estimated. We sampled 1,425 individuals from 99 species and 39 families, with an estimated total density of 5,700 individuals by hectare. The richest families were Fabaceae (13), Myrtaceae (10) and Lauraceae (7). The H’ was 3.76 and the J was 0.80. The TNR rate ranged from 0.05 to 8.12%, highlighting Trichilia elegans, with the highest rate and Araucaria angustifolia with low potential for natural regeneration. The analysis of the results indicated a high diversity in the regenerating component of the PEAR compared to other studies, probably because the area presents itself as a successional mosaic due to past disturbances.
O estudo da regeneração florestal permite diagnosticar o estado de conservação de fragmentos florestais e estimar os parâmetros populacionais que são imprescindíveis para o manejo florestal. Este estudo avaliou a estrutura, a diversidade e a dinâmica do componente regenerante arbóreo de um remanescente de floresta ombrófila mista, visando dar suporte cientifico às ações de gestão e manejo para este tipo florestal. O estudo foi desenvolvido no Parque Estadual das Araucárias (PEAR), localizado na região oeste de Santa Catarina, sul do Brasil. Foram alocadas 100 parcelas de 25 m2 (0.25 ha) e, nestas, foram amostrados todos os indivíduos com altura maior ou igual a 1.0 m e diâmetro à altura do peito menor que 5 cm. Foram estimados os índices de diversidade de Shannon (H’) e de equabilidade de Pielou (J) e a taxa de regeneração natural total (RNT). Foram amostrados 1.425 indivíduos pertencentes a 99 espécies e 39 famílias botânicas, com densidade total estimada de 5.700 indivíduos por hectare. As famílias com maior riqueza foram Fabaceae (13), Myrtaceae (10) e Lauraceae (7). O H’ foi de 3.76 e o J foi de 0.80. A taxa RNT variou de 0.05 a 8.12%, com destaque para Trichilia elegans, com a maior taxa de regeneração natural e Araucaria angustifolia com baixo potencial de regeneração natural. A análise dos resultados indicou alta diversidade no componente regenerante do PEAR, provavelmente em razão da área se apresentar como um mosaico sucessional em razão de perturbações pretéritas.
Atlantic forest, biodiversity, conservation, disturbance, heterogeneity, tree species
Araucaria, biodiversidade, conservação, espécies arbóreas, heterogeneidade, mata atlântica, perturbação
Natural regeneration is related to the ability of species to establish and develop after natural or anthropic disturbances (
The forests of the state of Santa Catarina (SC) were greatly impacted by human action (
Some studies on natural regeneration of MOF have been developed in SC (e.g.
The study was carried out at Parque Estadual das Araucárias (PEAR – 26°27'08"S, 52°33'56"W), western SC, southern Brazil. This protected area (612 ha), created in May 2003, was previously used for the extraction and processing of wood, especially of Araucaria angustifolia.
According to the Köppen classification, the region’s climate is of the Cfb type – with mild summers (
On a PEAR map 100 plots of 100 m2 (10 m × 10 m) were allocated, seeking to represent all areas of the PEAR, but avoiding those that are difficult to access or particularly degraded (
We used the rarefaction curve and Jackknife2 method in order to compare the observed richness with the estimated richness (
The density and frequency (absolute and relative) of each species were calculated according to
The species’ natural regeneration rate by size class (NRC) was estimated by the equation NRC = RD + RF / 2 (
A total of 1,425 individuals belonging to 99 species distributed in 39 families were sampled, corresponding to an overall density of 5,700 individuals per hectare. The analysis of the rarefaction curve shows that the observed richness was less than the richness estimated by the Jackknife2 estimator, indicating that the species richness may be greater than that sampled (Fig.
The families with the highest species richness were Fabaceae (13), Myrtaceae (10), Lauraceae (7), Sapindaceae, Salicaceae and Meliaceae (5), which together represented 46.6% of the total species.
Natural regeneration in the PEAR showed a Shannon diversity index of 3.76 nats ind.-1 and a Pielou equability index of 0.8. The species with the highest density were Nectandra megapotamica, Coussarea contracta (Walp.) Müll.Arg., Trichilia elegans A.Juss., Cupania vernalis and Cestrum bracteatum Link & Otto, which accounted for 29.3% of the total absolute density of regenerants (Table
Regenerating tree species sampled at the Parque Estadual das Araucárias, Santa Catarina, southern Brazil. N = number of individuals sampled; SG = successional group (P = pioneer, S = secondary, C = clímax); DS = dispersal syndrome (Z = zoochory, A = anemochory, Au = autochory); AD = absolute density (ind ha-1); RD = relative density (%); AF = absolute frequency (%); RF = relative frequency (%); NRC1, NRC2, NRC3 (%) = natural regeneration rate in classes 1, 2 and 3, respectively; TNR = potential total natural regeneration rate.
Species | N | SG | DS | AD | RD | AF | RF | NRC1 | NRC2 | NRC3 | TNR |
---|---|---|---|---|---|---|---|---|---|---|---|
Nectandra megapotamica (Spreng.) Mez | 119 | S | Z | 476 | 8.35 | 36 | 5.22 | 7.65 | 6.87 | 6.89 | 7.14 |
Coussarea contracta (Walp.) Mull.Arg. | 109 | P | Z | 436 | 7.65 | 30 | 4.35 | 5.83 | 6.40 | 8.59 | 6.94 |
Trichilia elegans A.Juss | 103 | S | Z | 412 | 7.23 | 36 | 5.22 | 4.95 | 8.84 | 10.57 | 8.12 |
Cupania vernalis Cambess. | 86 | P | Z | 344 | 6.04 | 36 | 5.22 | 5.95 | 5.38 | 7.64 | 6.33 |
Cestrum bracteatum Link & Otto | 69 | S | Z | 276 | 4.84 | 30 | 4.35 | 4.41 | 4.45 | 5.86 | 4.90 |
Matayba elaeagnoides Radlk. | 57 | S | Z | 228 | 4.00 | 30 | 4.35 | 5.35 | 3.42 | 1.83 | 3.53 |
Ocotea diospyrifolia (Meisn.) Mez | 51 | C | Z | 204 | 3.58 | 24 | 3.48 | 1.50 | 1.91 | 3.04 | 2.15 |
Luehea divaricata Mart. | 49 | S | A | 196 | 3.44 | 16 | 2.32 | 2.22 | 2.94 | 5.55 | 3.57 |
Nectandra grandiflora Ness | 49 | S | Z | 196 | 3.44 | 8 | 1.16 | 2.46 | 3.60 | 0.91 | 2.32 |
Casearia decandra Jacq. | 45 | S | Z | 180 | 3.16 | 23 | 3.34 | 3.08 | 3.30 | 3.58 | 3.32 |
Parapiptadenia rigida (Benth.) Brenan. | 43 | S | A | 172 | 3.02 | 24 | 3.48 | 3.58 | 2.48 | 2.74 | 2.94 |
Allophylus edulis (A.St.-Hil. et al.) Hieron. ex Niederl | 34 | S | Z | 136 | 2.39 | 15 | 2.18 | 2.10 | 2.84 | 2.40 | 2.45 |
Allophylus guaraniticus (A.St.-Hil.) Radlk. | 32 | C | Z | 128 | 2.25 | 18 | 2.61 | 2.21 | 3.05 | 2.28 | 2.52 |
Prunus myrtifolia (L.) Urb. | 30 | S | Z | 120 | 2.11 | 14 | 2.03 | 2.09 | 1.60 | 3.58 | 2.42 |
Sorocea bonplandii (Bail.) W.C.Burger, Lanj. & Boer | 30 | S | Z | 120 | 2.11 | 10 | 1.45 | 1.63 | 1.39 | 2.58 | 1.87 |
Campomanesia xanthocarpa (Mart.) O.Berg | 29 | S | Z | 116 | 2.04 | 21 | 3.05 | 3.02 | 1.81 | 0.46 | 1.76 |
Diatenopteryx sorbifolia Radlk. | 29 | P | Z | 116 | 2.04 | 21 | 3.05 | 2.62 | 1.91 | 1.56 | 2.03 |
Ocotea puberula (Rich.) Nees | 29 | P | A | 116 | 2.04 | 11 | 1.60 | 0.93 | 1.24 | 0.46 | 0.88 |
Trichilia clausseni C.DC. | 25 | S | Z | 100 | 1.75 | 15 | 2.18 | 1.69 | 3.05 | 2.28 | 2.34 |
Urera baccifera (L.) Gaudich. ex Wedd. | 21 | S | Z | 84 | 1.47 | 15 | 2.18 | 2.47 | 0.73 | 0.00 | 1.07 |
Cinnamomum amoenum (Ness & Mart). Kosterm. | 19 | S | Z | 76 | 1.33 | 6 | 0.87 | 1.13 | 0.88 | 1.56 | 1.19 |
Ilex paraguariensis A.St.-Hil. | 17 | P | Z | 68 | 1.19 | 9 | 1.31 | 0.61 | 2.64 | 1.37 | 1.54 |
Actinostemon concolor (Spreng.) Müll.Arg. | 16 | C | Au | 64 | 1.12 | 1 | 0.15 | 0.82 | 0.67 | 0.46 | 0.65 |
Muellera campestris (Mart. ex Benth.) M.J.Silva & A.M.G.Azevedo | 16 | S | A | 64 | 1.12 | 10 | 1.45 | 1.70 | 0.73 | 0.46 | 0.96 |
Sebastiania commersoniana (Baill.) L.B.Sm. & Downs | 16 | P | Au | 64 | 1.12 | 7 | 1.02 | 1.01 | 1.24 | 0.91 | 1.05 |
Syagrus romanzoffiana (Cham.) Glassman. | 14 | P | Z | 56 | 0.98 | 9 | 1.31 | 0.49 | 2.69 | 1.10 | 1.43 |
Chrysophyllum marginatum (Hook. & Arn.) Radlk. | 13 | S | Z | 52 | 0.91 | 10 | 1.45 | 0.99 | 1.81 | 0.00 | 0.94 |
Myrocarpus frondosus Allemão | 13 | S | A | 52 | 0.91 | 11 | 1.60 | 1.52 | 0.00 | 1.37 | 0.96 |
Ocotea pulchella (Ness & Mart.) Mez | 12 | P | Z | 48 | 0.84 | 7 | 1.02 | 3.72 | 4.81 | 1.37 | 3.30 |
Cordia americana (L.) Gottschling & J.E.Mill. | 11 | C | A | 44 | 0.77 | 8 | 1.16 | 0.71 | 1.60 | 0.46 | 0.92 |
Annona rugulosa (Schltdl.) H.Rainer | 10 | P | Z | 40 | 0.70 | 8 | 1.16 | 0.98 | 0.73 | 0.91 | 0.87 |
Cordyline spectabilis Kunth & Bouché | 10 | S | Z | 40 | 0.70 | 7 | 1.02 | 0.49 | 1.76 | 0.46 | 0.90 |
not identified | 10 | - | - | 40 | 0.70 | 8 | 1.16 | 0.65 | 1.45 | 0.91 | 1.00 |
Ruprechtia laxiflora Meisn. | 10 | S | A | 40 | 0.70 | 8 | 1.16 | 0.93 | 0.73 | 0.46 | 0.70 |
Casearia sylvestris Sw. | 9 | S | Z | 36 | 0.63 | 7 | 1.02 | 0.81 | 0.73 | 0.91 | 0.82 |
Clethra scabra Pers. | 9 | S | A | 36 | 0.63 | 4 | 0.58 | 0.67 | 0.00 | 0.84 | 0.50 |
Cordiera concolor (Cham). Kuntze | 9 | C | Z | 36 | 0.63 | 4 | 0.58 | 0.83 | 0.36 | 0.46 | 0.55 |
Cedrela fissilis Vell. | 8 | S | A | 32 | 0.56 | 4 | 0.58 | 0.33 | 0.73 | 1.29 | 0.78 |
Myrcia oblongata D.C. | 8 | P | Z | 32 | 0.56 | 4 | 0.58 | 0.67 | 0.36 | 0.46 | 0.50 |
Nectandra lanceolata Nees | 8 | S | Z | 32 | 0.56 | 5 | 0.73 | 0.77 | 0.36 | 0.46 | 0.53 |
Casearia obliqua Spreng. | 6 | S | Z | 24 | 0.42 | 4 | 0.58 | 0.33 | 0.00 | 1.29 | 0.54 |
Celtis iguanaea (Jacq.) Sarg. | 6 | P | Z | 24 | 0.42 | 3 | 0.44 | 0.34 | 0.36 | 0.46 | 0.39 |
Eugenia uniflora L. | 5 | S | Z | 20 | 0.35 | 3 | 0.44 | 0.38 | 0.52 | 0.00 | 0.30 |
Machaerium stipitatum Vogel | 5 | S | A | 20 | 0.35 | 4 | 0.58 | 0.49 | 0.00 | 0.91 | 0.47 |
Myrsine loefgrenii (Mez) Imkhan. | 5 | S | Z | 20 | 0.35 | 3 | 0.44 | 0.22 | 1.09 | 0.00 | 0.44 |
Peltophorum dubium (Spreng.) Taub | 5 | P | A | 20 | 0.35 | 2 | 0.29 | 0.28 | 0.36 | 0.46 | 0.37 |
Zanthoxylum rhoifolium Lam. | 5 | S | Z | 20 | 0.35 | 4 | 0.58 | 0.49 | 0.00 | 0.65 | 0.38 |
Apuleia leiocarpa (Vogel) J.F.Macbr. | 4 | P | A | 16 | 0.28 | 1 | 0.15 | 0.22 | 0.00 | 0.65 | 0.29 |
Ateleia glazioveana Baill. | 4 | P | A | 16 | 0.28 | 2 | 0.29 | 0.38 | 0.00 | 0.46 | 0.28 |
Banara tomentosa Clos | 4 | S | Z | 16 | 0.28 | 4 | 0.58 | 0.33 | 0.36 | 0.46 | 0.38 |
Campomanesia guazumifolia (Cambess.) O.Berg | 4 | S | Z | 16 | 0.28 | 3 | 0.44 | 0.49 | 0.00 | 0.46 | 0.31 |
Eugenia ramboi D.Legrand | 4 | S | Z | 16 | 0.28 | 3 | 0.44 | 0.55 | 0.00 | 0.00 | 0.18 |
Inga virescens Benth. | 4 | S | Z | 16 | 0.28 | 4 | 0.58 | 0.65 | 0.00 | 0.00 | 0.22 |
Mollinedia triflora (Spreng.) Tul. | 4 | S | Z | 16 | 0.28 | 4 | 0.58 | 0.33 | 0.36 | 0.46 | 0.38 |
Solanum mauritianum Scop. | 4 | S | Z | 16 | 0.28 | 2 | 0.29 | 0.22 | 0.73 | 0.00 | 0.32 |
Styrax leprosus Hook. & Arn. | 4 | S | Z | 16 | 0.28 | 4 | 0.58 | 0.65 | 0.00 | 0.00 | 0.22 |
Annona neosalicifolia H.Rainer | 3 | P | Z | 12 | 0.21 | 2 | 0.29 | 0.33 | 0.36 | 0.00 | 0.23 |
Ilex brevicuspis Reissek | 3 | S | Z | 12 | 0.21 | 2 | 0.29 | 0.00 | 0.73 | 0.46 | 0.39 |
Machaerium paraguariense Hassl. | 3 | S | A | 12 | 0.21 | 3 | 0.44 | 0.16 | 0.73 | 0.00 | 0.30 |
Miconia cinerascens Miq | 3 | P | Au | 12 | 0.21 | 3 | 0.44 | 0.49 | 0.00 | 0.00 | 0.16 |
Myrsine coriacea (Sw.) R.Br. ex Roem. & Schult. | 3 | P | Z | 12 | 0.21 | 3 | 0.44 | 0.49 | 0.00 | 0.00 | 0.16 |
Strychnos brasiliensis Mart. | 3 | S | Z | 12 | 0.21 | 3 | 0.44 | 0.16 | 0.36 | 0.46 | 0.33 |
Zanthoxylum fagara (L.) Sarg. | 3 | S | Z | 12 | 0.21 | 2 | 0.29 | 0.38 | 0.00 | 0.00 | 0.13 |
Zanthoxylum petiolare A.St-Hil. & Tul | 3 | S | Z | 12 | 0.21 | 3 | 0.44 | 0.49 | 0.00 | 0.00 | 0.16 |
Albizia edwallii (Hoehne) Barneby & J.W.Grimes | 2 | S | A | 8 | 0.14 | 1 | 0.15 | 0.00 | 0.36 | 0.46 | 0.27 |
Albizia niopoides (Spruce ex Benth.) Burkart | 2 | P | A | 8 | 0.14 | 2 | 0.29 | 0.33 | 0.00 | 0.00 | 0.11 |
Araucaria angustifolia (Bertol.) Kuntze | 2 | P | Z | 8 | 0.14 | 2 | 0.29 | 0.33 | 0.00 | 0.00 | 0.11 |
Balfourodendron riedelianum (Engl.) Engl. | 2 | S | A | 8 | 0.14 | 2 | 0.29 | 0.33 | 0.00 | 0.00 | 0.11 |
Brunfelsia cuneifolia J.A.Schmidt | 2 | P | Z | 8 | 0.14 | 2 | 0.29 | 0.16 | 0.00 | 0.46 | 0.21 |
Chrysophyllum gonocarpum (Mart. & Eichler ex Miq.) Engl. | 2 | S | Z | 8 | 0.14 | 1 | 0.15 | 0.00 | 0.00 | 0.65 | 0.22 |
Erythoxylum deciduum A.St.-Hil. | 2 | S | Z | 8 | 0.14 | 2 | 0.29 | 0.33 | 0.00 | 0.00 | 0.11 |
Erythroxylum myrsinites Mart | 2 | S | Z | 8 | 0.14 | 2 | 0.29 | 0.33 | 0.00 | 0.00 | 0.11 |
Eugenia involucrata DC. | 2 | S | Z | 8 | 0.14 | 2 | 0.29 | 0.33 | 0.00 | 0.00 | 0.11 |
Myrcianthes gigantea (D.Legrand). D.Legrand | 2 | S | Z | 8 | 0.14 | 2 | 0.29 | 0.33 | 0.00 | 0.00 | 0.11 |
Myrsine umbellata Mart. | 2 | S | Z | 8 | 0.14 | 2 | 0.29 | 0.16 | 0.00 | 0.46 | 0.21 |
Picrasma crenata (Vell.) Engl. | 2 | S | Z | 8 | 0.14 | 2 | 0.29 | 0.33 | 0.00 | 0.00 | 0.11 |
Psychotria suterella Müll.Arg. | 2 | - | A | 8 | 0.14 | 1 | 0.15 | 0.22 | 0.00 | 0.00 | 0.07 |
Sapium glandulosum (L.) Morong | 2 | P | Z | 8 | 0.14 | 2 | 0.29 | 0.16 | 0.00 | 0.46 | 0.21 |
Symplocos pentandra (Mattos) Occhioni ex Aranha | 2 | S | Z | 8 | 0.14 | 2 | 0.29 | 0.00 | 0.36 | 0.46 | 0.27 |
Trichilia catigua A.Juss | 2 | C | Z | 8 | 0.14 | 2 | 0.29 | 0.16 | 0.00 | 0.46 | 0.21 |
Aegiphila brachiata Vell. | 1 | S | Z | 4 | 0.07 | 1 | 0.15 | 0.00 | 0.36 | 0.00 | 0.12 |
Brunfelsia pilosa Plowman | 1 | P | Z | 4 | 0.07 | 1 | 0.15 | 0.00 | 0.36 | 0.00 | 0.12 |
Cabralea canjerana (Vell.) | 1 | S | Z | 4 | 0.07 | 1 | 0.15 | 0.16 | 0.00 | 0.00 | 0.05 |
Cordia ecalyculata Vell. | 1 | S | A | 4 | 0.07 | 1 | 0.15 | 0.16 | 0.00 | 0.00 | 0.05 |
Dalbergia frutescens (Vell.) Britton | 1 | S | A | 4 | 0.07 | 1 | 0.15 | 0.16 | 0.00 | 0.00 | 0.05 |
Eugenia burkartiana (D.Legrand) D.Legrand | 1 | C | Z | 4 | 0.07 | 1 | 0.15 | 0.16 | 0.00 | 0.00 | 0.05 |
Ilex microdonta Reissek | 1 | S | Z | 4 | 0.07 | 1 | 0.15 | 0.00 | 0.36 | 0.00 | 0.12 |
Maytenus aquifolia Mart. | 1 | - | Z | 4 | 0.07 | 1 | 0.15 | 0.16 | 0.00 | 0.00 | 0.05 |
Mimosa scabrella Benth. | 1 | S | A | 4 | 0.07 | 1 | 0.15 | 0.16 | 0.00 | 0.00 | 0.05 |
Myrceugenia glaucescens (Cambess.) D.Legrand & Kausel | 1 | S | Z | 4 | 0.07 | 1 | 0.15 | 0.00 | 0.36 | 0.00 | 0.12 |
Myrcia hatschbachii D.Legrand | 1 | S | Z | 4 | 0.07 | 1 | 0.15 | 0.16 | 0.00 | 0.00 | 0.05 |
Picramnia parvifolia Engl. | 1 | S | Z | 4 | 0.07 | 1 | 0.15 | 0.16 | 0.00 | 0.00 | 0.05 |
Roupala asplenioides Sleume | 1 | S | Z | 4 | 0.07 | 1 | 0.15 | 0.16 | 0.00 | 0.00 | 0.05 |
Rudgea parquioides (Cham.) Mull.Arg. | 1 | S | A | 4 | 0.07 | 1 | 0.15 | 0.16 | 0.00 | 0.00 | 0.05 |
Sambucus australis Cham. & Schltdl. | 1 | P | Z | 4 | 0.07 | 1 | 0.15 | 0.16 | 0.00 | 0.00 | 0.05 |
Schaefferia argentinensis Speg. | 1 | S | Z | 4 | 0.07 | 1 | 0.15 | 0.16 | 0.00 | 0.00 | 0.05 |
Schinus terebinthifolius Raddi | 1 | P | Au | 4 | 0.07 | 1 | 0.15 | 0.00 | 0.36 | 0.00 | 0.12 |
Vernonanthura discolor (Spreng.) H.Rob | 1 | P | A | 4 | 0.07 | 1 | 0.15 | 0.00 | 0.00 | 0.46 | 0.15 |
Xylosma pseudosalzmanii Sleumer | 1 | S | Z | 4 | 0.07 | 1 | 0.15 | 0.16 | 0.00 | 0.00 | 0.05 |
Total | 1425 | 5700 | 100 | 100 | 100 | 100 | 100 | 100 |
Of the 99 species sampled, 18% (18 spp.) are considered rare in the PEAR because they have only one individual. The regenerating component showed high floristic similarity with the tree component (Sorensen similarity index = 0.79). Species exclusive to natural regeneration (17) are rare locally, presenting mostly one individual. Most of the exclusive species (12) are secondary, which indicates that they are finding favorable conditions for germination and establishment in the PEAR. The absence of Dicksonia sellowiana Hook. and Alsophila setosa Kaulf. should be highlighted in the regenerating component.
The most frequent dispersal syndrome was the zoochory with 71% of the species and 1,157 individuals, followed by anemochory (23% and 222 individuals) and autochory (4% and 36 individuals). As for the successional category, 65% of the species are secondary, 25% pioneer, 7% climax and 3% without information (Table
In the class 1, 3,340 ind ha-1 were sampled, belonging to 89 species and 35 families; in the class 2, 1,304 ind ha-1, 56 species and 26 families; and in the class 3, 1,056 ind ha-1, 58 species and 26 families. There was a reduction in the number of individuals from the class 1 to class 3 (Fig.
Regarding the size classes, 41% of the species occurred in all size classes. Twenty-nine species occurred only in class 1, five species were sampled only in class 2 and Vernonanthura discolor (Spreng.) H.Rob. occurred exclusively in class 3. However, this species is rare locally in natural regeneration with only one individual. TNR values ranged from 0.05 to 8.12% (Table
Number of individuals by size classes of tree natural regeneration in Parque Estadual das Araucárias, Santa Catarina, southern Brazil. Class 1 = height between 1.0 m and 2.0 m; class 2 = height between 2.01 m and 3.0 m; class 3 = height above 3.0 m and diameter at breast height less than 5 cm.
The study area underwent logging for decades (
As for families with greater specific richness, studies have shown that the MOF tends to follow a floristic pattern, with emphasis on Myrtaceae and Lauraceae (
The regenerating component showed high similarity with the PEAR tree component (
Among the five species best positioned in the density ranking in the regenerating component of PEAR, only Cupania vernalis, Casearia decandra and Matayba elaeagnoides are common with those best positioned in other fragments of MOF in the south of SC (
Among the species with the highest density and frequency in the regenerating component, N. megapotamica stood out, which had already been highlighted in the PEAR tree stratum, forming an association with A. angustifolia (
Similar to the tree component (
The values recorded for the TNR in the PEAR were lower than those observed by
Considering natural regeneration as a whole, 41% of species occurred in all height classes. These species, with more regular distribution in the different growth phases, are more likely to compose the forest structure in the future (
Trichilia elegans showed the highest TNR (8.12%), mainly because the species obtained the highest NRC in classes 2 and 3. In one of the plots sampled in the PEAR by the IFFSC (
The low value of TNR for A. angustifolia is consistent with other studies (
Another issue to be considered may be the reduction in the number of propagules and young individuals of A. angustifolia in the PEAR. Despite the presence of reproductive adults, park rangers and researchers have observed the ringing of the stem of young plants, which can lead to death for the individual, as well as the large amount of pine cones with immature seeds on the forest floor. One of those responsible for these practices (already registered by park rangers) is Sapajus nigritus Goldfuss, 1809 (capuchin monkey), which has a high population density in the PEAR (
On the other hand,
In general, the high similarity between the studies of natural regeneration and the tree component indicates that the composition of the forest will suffer little change in the future if the current conditions are maintained. However, the absence or low regeneration of A. angustifolia, D. sellowiana and A. setosa, as well as other species of MOF, such as O. porosa and M. scabrella can imply important floristic changes, such as the invasion by species typical of the seasonal forest. According to
The Parque Estadual das Araucárias, in addition to the past anthropic disturbance (logging), presents variations of relief, which favors the occurrence of different habitats. This heterogeneity of habitats made it possible to record high species richness and diversity in the tree regenerating component. However, the calculation of the estimated richness indicates that the number of species may be even greater. Because it is a protected area, the presence of park rangers and constant monitoring ensures that destructive human activities are reduced or nullified in the PEAR, allowing biodiversity to be conserved.
The low value obtained for the TNR for A. angustifolia is in agreement with the results of other studies, since it is a heliophile species. Therefore, its establishment in the interior of the forest is difficult due to the shading, and consequently, its conservation in situ is more complex.
The similarity of species between natural regeneration and the tree component indicates that, in the future, there will be little change in species composition. However, the absence (or decrease) of the regeneration of some typical species of MOF, such as A. angustifolia, in addition to climate changes, may result in a change in the area’s phytophysiognomy in the future. Therefore, silvicultural treatments and enrichment plantations can be implemented in the PEAR, aiming at the conservation of typical MOF species of this region, such as Dicksonia sellowiana and Alsophila setosa. In the specific case of A. angustifolia, enrichment plantation in areas with the most open vegetation in the PEAR can contribute to the conservation of this species.
We thank the Fundação de Amparo à Pesquisa e Inovação no Estado de Santa Catarina (FAPESC); National Science Foundation and São Paulo State Research Support Foundation for the postdoctoral fellowship (NSF-FAPESP PIRE-CREATE project grants 2017/50085-3 and 2019/27110-7); Specialists who assisted in the identification: Martin Grings and André Luiz de Gasper; This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)–Brazil–Finance Code 001.