ABSTRACT: The Legado Verdes do Cerrado Sustainable Development Reserve is home to the largest private contiguous area of native vegetation in the Cerrado (Brazilian Savanna) biome, but its flora is still little studied. A floristic and phytosociological study was carried out in four phytophysiognomies of the Reserve (cerrado sensu stricto, cerradão, dry forest and ciliary forest). Eighty 10 x 10-m plots were systematically installed, with 20 in each phytophysiognomy. All live woody individuals with diameter at breast height ≥ 5 cm and height greater than 130 cm were measured. A total of 933 live individuals were sampled, with an estimated density of 1,166 ind ha-1, belonging to 154 species and 46 families. Diversity and equability were assessed at 4.47 nats ind-1 and 0.88, respectively. The diametric distribution of the individuals showed a negative exponential (reverse J), while the one for height classes showed a tendency towards normal distribution. Species richness and structural parameters were within the values found for native vegetation, except for the cerrado sensu stricto.
KEYWORDS: Native vegetationNative vegetation,biodiversitybiodiversity,conservation unitsconservation units.
RESUMO: A Reserva de Desenvolvimento Sustentável Legado Verdes do Cerrado abriga a maior área contígua particular de vegetação nativa do bioma Cerrado, porém, com flora ainda pouco estudada. Objetivou-se realizar estudo florístico e fitossociológico em quatro fitofisionomias da Reserva (cerrado sentido restrito, cerradão, mata seca e mata ciliar). Foram instaladas de forma sistemática 80 parcelas de 10 x 10 m, 20 em cada fitofisionomia. Todos os indivíduos lenhosos vivos com diâmetro à altura do peito ≥ 5 cm e altura superior a 130 cm foram mensurados. No total, foram amostrados 933 indivíduos vivos, densidade estimada em 1.166 ind ha-1, pertencentes a 154 espécies e 46 famílias. A diversidade e a equabilidade foram avaliadas em 4,47 nats ind-1 e 0,88, respectivamente. A distribuição diamétrica dos indivíduos apresentou exponencial negativo (J-reverso) e a de classes de altura mostrou tendência à distribuição normal. A riqueza de espécies e os parâmetros estruturais obtidos estão dentro dos valores encontrados para vegetações nativas, com exceção do cerrado sentido restrito.
PALAVRAS-CHAVE: Vegetação nativa, biodiversidade, unidades de conservação.
Special Supplement: Cerrado [Brazilian Savanna]
Floristic and structural aspects of Brazilian Savanna phytophysiognomies in the northern Goiás state, Brazil
Aspectos florísticos e estruturais de fitofisionomias de Cerrado no norte do estado de Goiás
Indiara Nunes Mesquita Ferreira indiaranunes@outlook.com
Fernanda Gomes Ferreira gomesfernanda@hotmail.com
Sabrina do Couto de Miranda sabrina.couto@ueg.br
Rafael Tassinari Resende rafael.tassinari@ufg.br
Fábio Venturoli venturoli@ufg.br
Received: 19 March 2021
Accepted: 30 April July 2021
The Cerrado (Brazilian Savanna) biome owns diverse landscapes and vegetation that form a true mosaic (Bueno et al. 2018, Felfili & Felfili 2001). At least 25 phytophysiognomies have already been mentioned in the literature, considering subtypes, inserted in forests, savannas and grasslands formations (Ribeiro & Walter 2008, Walter et al. 2015). Despite its biological relevance, much of the Cerrado vegetation is fragmented, with around 50-55 % of its original coverage remaining (Françoso et al. 2015, Sano et al. 2019, Alencar et al. 2020). Of this total, only 3 % is considered strictly protected in conservation units (Françoso et al. 2015). The creation and implementation of conservation units are important tools for protecting biodiversity. However, to be effective, they need to be concretely implemented, with adequate management levels (Coelho & Rezende 2016).
The Reserva de Desenvolvimento Sustentável Legado Verdes do Cerrado (Legado Verdes do Cerrado Sustainable Development Reserve - LVC), located in Niquelândia, in the northern region of the Goiás state, Brazil, is a type of conservation unit that falls under the sustainable development reserve category. The LVC is home to a flora that has been poorly studied. Botanical collections of arboreal plants in the region are restricted to a study by Mendonça et al. (2007), who sampled a nearby area in Chapada dos Veadeiros. However, there is no specific floristic list or structural data for the region’s vegetation.
It is important to emphasize the importance of floristic and phytosociological studies that aim to acquire knowledge and conserve remaining native areas. These studies generate data on the species distribution, frequency and dominance, and provide a basis to propose management plans involving areas or species (Batista et al. 2019). In addition, the registration of the deposit (voucher) of samples (exsiccates) in herbariums is essential for future studies related to taxonomic and occurrence data of the sampled species. According to Castro et al. (1999), a good taxonomy is preceded by good collections, with systematic visits to study sites, in order to sample plants in their reproductive phases, although it is difficult to obtain these data in a short period of time.
In this context, this study aimed to contribute to the biodiversity knowledge and conservation in the LVC, as well as to generate data on the different Cerrado woody communities present in the conservation unit. This study was guided by the following questions: 1) How is the flora of the cerrado sensu stricto, cerradão, dry forest and ciliary forest phytophysiognomies in the LVC composed?; 2) How are the four plant communities in the LCV structured, considering the horizontal (diameter) and vertical (height) structure of the arboreal vegetation?
The study was carried out in four Cerrado phytophysiognomies (cerrado sensu stricto, cerradão, dry forest and ciliary forest) (Ribeiro & Walter 2008) within the Reserva de Desenvolvimento Sustentável Legado Verdes do Cerrado (Legado Verdes do Cerrado Sustainable Development Reserve - LVC), in Niquelândia, Goiás state, Brazil (14º29’55”S; 48º28’5”W) (Figure 1), between October 2017 and December 2020.
The LVC belongs to the Companhia Brasileira de Alumínio and encompasses 32,000 ha (about 80 % being native vegetation). The area is of relevant ecological interest, as it houses a variety of phytophysiognomies of the Cerrado biome, from forest to savanna and grassland formations (Ribeiro & Walter 2008).
The floristic and phytosociological inventory was performed with the systematic allocation of twenty 10 x 10-m plots spaced equidistantly (50 m) in each phytophysiognomy, for a total of 80 plots/sample unit. All live woody individuals with a diameter at breast height (DBH) ≥ 5 cm and height greater than 130 cm were numbered with metal plates and subsequently measured for diameter and total height, the latter with the aid of a clinometer.
Fertile samples were collected and deposited in the herbariums of the Universidade Federal de Goiás (UFG) (Goiânia, Goiás state) and Cenargen-Embrapa (Brasília, Federal District), both in Brazil. The botanical families followed the classification system of the Angiosperm Phylogeny Group IV (Chase et al. 2016), while spelling, authorship and synonymy of scientific names were confirmed by consulting Flora do Brasil (Rio de Janeiro 2020). The choice of forest phytophysiognomies, plot size, inclusion criteria for arboreal individuals and botanical collection followed the National Forest Inventory standards (SFB 2015), in order to ultimately include the results in its database.
The structure of woody communities was explained by means of phytosociological parameters described by Mueller-Dombois & Ellenberg (2002). Floristic diversity was assessed using the Shannon’s diversity index (H’) and Pielou’s equability (J’) (Magurran 2019). The sampling sufficiency in each phytophysiognomy was assessed using species accumulation and rarefaction curves (Mao tau) (Colwell et al. 2004). The floristic similarity among the phytophysiognomies was calculated using the Dice-Sorensen index, with grouping via dendrogram, using the unweighted pair group method with arithmetic mean (UPGMA). The analyses were performed using the PAST software, version 4.03 (Hammer et al. 2001). Horizontal (diameters) and vertical (heights) structures were analyzed using frequency histograms in the R statistical environment (R Core Team 2020). The Spiegel formula (Spiegel 1976) was used to determine the ideal interval for the distribution of data among the classes.
The Cerrado communities sampled in the LVC showed a high floristic diversity (H’ between 3.04 and 3.94) and equitable distributions of individuals among the sampled species (J’ between 0.84 and 0.92) (Table 1). Our results are similar to those of Silva et al. (2019) for three areas of cerrado sensu stricto (H’ from 3.20 to 3.62), and within the range found by Miranda et al. (2017) for 12 areas of cerradão (2.13 to 4.00). The results obtained for dry and ciliary forests were superior to those found, respectively, by Walter et al. (2015) (2.98) and Ferreira et al. (2017) (3.25), as well as by Silva et al. (2015) (3.32) and Gomes et al. (2014) (3.62).
The total floristic survey sampled 933 live individuals, with estimated 1,166 ind ha-1. These individuals represent 154 species, belonging to 103 genera and 46 botanical families (Tables 2a-d). Of the 154 species, three were identified only to the family level and five to genus. The five richest families (Fabaceae, Myrtaceae, Malpighiaceae, Malvaceae and Vochysiaceae) accounted for 63 % of the total number of individuals sampled. Of this total, eight families were common to all phytophysiognomies (Anacardiaceae, Annonaceae, Apocynaceae, Fabaceae, Myrtaceae, Nyctaginaceae, Sapindaceae and Vochysiaceae) and, thus, representative in the tree strata of the Cerrado biome. Fabaceae, with 39 species, stood out regarding richness, accounting for 25 % of the total. Fabaceae was also the richest family in each of the different communities studied. This family is considered one of the largest in the world, and has a great importance for nitrogen balance in savanna ecosystems (Goodland & Ferri 1979).
The genera with the greatest richness were Byrsonima (cerrado sensu stricto and cerradão) and Machaerium (dry and ciliary forests). Byrsonima is common in the Cerrado with about 130 species (Mamede & Francener 2015) that are distributed in various types of plant formations (Mendonça et al. 2008), while Machaerium has 22 species in the same biome and is more common in forest areas (Rio de Janeiro 2020). The flora sampled in this study included species in common with the floristic list of Mendonça et al. (2008) and added to the list generated by Mendonça et al. (2007) for the Parque Nacional da Chapada dos Veadeiros, a nearby area, namely: Oxandra sp.; Syagrus oleracea (Mart.) Becc.; Erythroxylum citrifolium A. St.-Hil.; Inga ingoides (Rich.) Willd.; Myroxylon peruiferum L. f.; Stryphnodendron rotundifolium Mart.; Swartzia multijuga Vogel; Byrsonima guilleminiana A. Juss.; Agonandra excelsa Griseb.; and Myrsine gardneriana A. DC. It is noteworthy that E. citrifolium, M. peruiferum and A. excelsa are quite common in the studied phytophysiognomies of the LVC. The great Cerrado heterogeneity (Ratter et al. 2003, Costa-Coutinho et al. 2019) highlights the importance of establishing conservation units such as the LVC to protect species that occur regionally. Among the species sampled in the present research, Apuleia leiocarpa (Vogel) J. F. Macbr. and Cedrela fissilis Vell. are considered vulnerable (Lima et al. 2013), with recommendations for the monitoring of populations and the implementation of sustainable management strategies. In general, more than 30 % of the woody species found in the communities are considered locally rare, that is, they are represented by a single individual. Of the four sampled communities, the dry forest had the highest percentage of rare species (Table 1). These species are important in the floristic differentiation of Cerrado communities and contribute to the genetic diversity of these areas.
The sampling methodology proved to be sufficient for dry forest, ciliary forest and cerradão (Figures 2B, 2C and 2D). However, it represented only 50 % of the estimated richness for the cerrado sensu stricto (Figure 2A).
According to Felfili et al. (2005), the sampling sufficiency in this community can be obtained using the inclusion criterion of woody individuals with a base diameter ≥ 5 cm and a minimum sampling of one hectare. It is noteworthy that the methodology adopted in this study sought to standardize data for inclusion in the National Forest Inventory database, which diverges from the criteria proposed by Felfili et al. (2005).
The floristic similarities between cerradão and cerrado sensu stricto and between these and the dry forest were high (Figure 3).
In fact, most of the species occurring in the cerradão (71 %) were shared with other phytophysiognomies, corroborating that this phytophysiognomy is characterized by the presence of species from cerrado sensu stricto and those occurring in different forest formations (Ribeiro & Walter 2008, Ferreira et al. 2017). Geographical proximity and, consequently, similarities in local environmental conditions may have contributed to the overlap of species among these phytophysiognomies (Pinto et al. 2009, Ferreira et al. 2019). The ciliary forest was the most distinct phytophysiognomy of the four, sharing 40 % of its species with dry forest (Figure 3) and with 47 % exclusive species, probably due to the environmental conditions of association with a water source (Silva et al. 2015).
The analysis of the phytosociological parameters of the four communities revealed that Anadenanthera peregrina (L.) Speg, Curatella americana L. and Dilodendron bipinnatum Radlk. were the most important species, accounting for 12 % of the total importance value (IV). The C. americana species stood out as the most abundant in the joint analysis of the communities, with greater density and frequency, and occurring in three of the four formations, the exception being ciliary forest. This species was the most important in the cerrado sensu stricto (20 % of the total IV) and the sixth most important in cerradão (4 % of the total IV). Matching results were found for the same species in different studies undertaken in the Cerrado (Ratter et al. 2003, Ferreira et al. 2017, Silva et al. 2019, Brasil 2020).
In the cerradão, Tachigali vulgaris L. G. Silva & H. C. Lima was the most important species (7 % of the total IV) and had the highest values for density and dominance. The species is considered an indicator of dystrophic cerradão (Oliveira-Filho & Ratter 2002, Vasconcelos et al. 2020), although there are records of its occurrence in several areas of the Cerrado biome (Ratter et al. 2003).
The A. peregrina species was the most important in the analysis of the four communities (5 % of the total IV), as well as in the dry forest (11 % of the total IV). It is a typical species of seasonal forests (Haidar 2008, Ribeiro & Walter 2008). In the ciliary forest, Aspidosperma subincanum Mart. had high values for density and frequency (50 % of the plots), being considered the most important species (6 % of the total IV), as well as the fifth most important in the dry forest (5 % of the total IV). This species was considered to have a wide geographical distribution, according to a National Forest Inventory floristic survey conducted in the Federal District and in the states of Bahia, Goiás, Maranhão, Mato Grosso do Sul, Piauí, Paraná and Tocantins (Brasil 2020).
The studied communities differed with regard to mean values for diameter and height (Table 1). The forest phytophysiognomies had an average DBH above 10 cm, while the cerrado sensu stricto (savanna formation) had an average of 8.6 cm. The highest coefficient of variation was found for the ciliary forest, at around 60 % (Table 1). The cerrado sensu stricto was characterized by shorter trees, with an average of 4.0 m (CV = 45 %), while, in the cerradão, the average height was 7.4 m (CV = 49 %), a result of sharing species with the cerrado sensu stricto and forest formations. The average tree height for forests was 11.0 m, with a greater coefficient of variation for the dry forest (63 %) (Table 1).
The forest formations had an estimated density above 1,000 ind ha-1, but the cerrado sensu stricto, due to the minimum criterion for inclusion in the sample, had an estimated density of 630 ind ha-1, a value lower than the range of 906 to 1,859 ind ha-1 obtained in recent studies carried out in areas of cerrado sensu stricto (Silva et al. 2019, Ferreira et al. 2020). Abiotic factors (e.g., soil physical and chemical properties) may also influence the structural parameters of Cerrado communities on a local scale (Miranda et al. 2020).
The minimum criterion for inclusion in sampling also influenced the values obtained for estimated basal area for the cerrado sensu stricto and cerradão. The forest phytophysiognomies had expressive values for basal area (Table 1), which were related to the presence of large individuals.
The distribution of arboreal individuals by diameter class revealed a reverse J aspect, indicating that, in general, the communities are self-regenerating, with a greater concentration of individuals in the smallest diameter classes (Figure 4). As the LVC is a conservation unit, the absence of anthropic disorders may be contributing to the balance between mortality and recruitment of new individuals in these communities (Lisboa et al. 2019).
The mean values for DBH and height corroborated the expected gradient, with the smallest mean diameter for the cerrado sensu stricto (8.6 cm) and the largest (11.4 cm) for the ciliary forest (Table 1). The coefficient of variation for all phytophysiognomies being above 45 % (Table 1) reflects a variation in the data set related to the Cerrado heterogeneity. The distribution among height classes (Figure 4) revealed a unimodal pattern tending to a normal distribution, with individuals grouped mainly in the second and third classes, as seen in other studies (Maracahipes et al. 2011, Ferreira et al. 2015).
