Abstract
One way to draw attention to an area regarding conservation is to declare it as an Atlantic Forest Biosphere Reserve (RBMA). In this article, we analyzed attributes related to different forest remnants, including the only RBMA of Santa Catarina state (Brazil), a modified old-growth Subtropical Atlantic Forest remnant. We brought evidences that patterns of distribution of species abundance and species diversity are influenced by highly dominant species. We found a relevant proportion of endemic tree/shrub species and three endangered species. These findings demonstrate the relevant biodiversity of the Subtropical Atlantic Forest of Santa Catarina. The diversity profiles of the RBMA and other areas overlapped. This finding, which has an important conservational implication that the tree species diversity in these areas is similar. Therefore, we concluded that the areas considered in our study deserve attention regarding biological conservation. New priority areas for conservation are necessary, and the establishment of new RBMA may be a way to achieve this goal.
Introduction
Biological diversity is a central theme in ecology and is often expressed in terms of species diversity (Liu, Whittaker, Ma, & Malcolm, 2007). This concept considers two attributes: (a) species richness and (b) the uniformity of distribution of species’ abundance (Hill, 1978; Hurlbert, 1971; Melo, 2008). Therefore, understanding the interaction between these attributes and their relation with the conservation status of a biological community is crucial, even more when species diversity is regarded as an essential attribute for identifying priority areas for conservation (Buckland, Studeny, Magurram, & Newson, 2011; Durigan et al., 2009).
The growing importance of Brazilian’s Atlantic Forest is stimulating the scientific community and government agencies to select priority areas for conservation (Anacleto, Ferreira, Diniz Filho, & Ferreira, 2005; Brasil, 2002, 2007a, 2007b; Durigan et al., 2009; Durigan, Siqueira, Franco, & Ratter, 2006; Galetti et al., 2009; Santos & Mantovani, 1999). These areas are usually selected based on the occurrence of rare and endangered species, species richness, level of endemism, and vegetation types (Joppa, Visconti, Jenkins, & Pimm, 2013; Margules & Pressey, 2000; Mews, Pinto, Eisenlohr, & Lenza, 2014; Pullin, Sutherland, Gardner, Kapos, & Fa, 2013). However, studies in tropical forests have suggested that species diversity is an important criterion, for it can vary among fairly conserved forests (Giam, Scheffers, Sodhi, Wilcove, Ceballos, & Ehrlich, 2012; Gibson et al., 2011; Sevegnani et al., 2013; Sevegnani, Vibrans, & Gasper, 2013). In this sense, species diversity plays a key role in defining the conservation status of tropical forests remnants.
On the other hand, if the community has few species with great abundance, some of the aforementioned issues might become contradictory. Hence, species diversity metrics must be used carefully (Imai et al., 2014). Well-conserved forests, for example, may yield lower species diversity when compared with less conserved forests, especially when using indices that address greater weight to the uniformity of species’ abundance distribution (Magurran, 2004; May, 1975; Melo, 2008; Oliveira, 2015). In addition, in some subtropical forests, the abundance and relative dominance of dominant species can be inversely proportional to the values yielded by species diversity indices (Oliveira, 2015).
Patterns of distribution of species abundance should be carefully verified when selecting areas for conservation, as they are related to the vegetation’s conservation status (Magurran, 2007). Very altered tropical forests might present few species with great abundance, and this could be related to species’ ecological adaptations (Pitman et al., 2001), to interspecific competition for space and resources (McGill et al., 2007) or, still, to processes of ecological succession (Volkov, Banavar, Hubbell, & Maritan, 2007). Meanwhile, these factors can also influence the formation of distribution patterns in conserved forests, where resource-demanding species may present great abundance, such as the brazilian-pine (
In Brazil, a program supported by the government called Atlantic Forest Biosphere Reserve (RBMA) has been standing out for selecting priority areas for conservation. The RBMA features a set of guidelines defined by UNESCO (RBMA, 2008) for selecting outposts which are intended to become centers of dissemination of ideas, concepts, programs, and projects developed by the each reserve (RBMA, 2014). One of the priority areas for conservation in the state of Santa Catarina (Southern Brazil) is the RBMA Chácara Edith Private Reserve of Natural Heritage (RPPN Chácara Edith). This reserve is the only RBMA in the state (ICMBio, 2011; RBMA, 2014). In this study, we considered the RPPN Chácara Edith as the reference area regarding ecological aspects of the vegetation. Therefore, due to the high degree of anthropic modification in the Subtropical Rainforest of Santa Catarina, we ask: Would not it be relevant that other areas might be regarded as priorities for conservation? On the basis of this question, we developed a case study involving forests remnants in different conservation status to demonstrate how differences in the patterns of distribution of tree species’ abundance—but not in species diversity—would reveal relevant implications for selecting areas for conservation. Our hypothesis was that the conservation status of a given forest remnant is not necessarily related to its species diversity, once dominant species lead to less uniform communities and, therefore, diversity indices would yield small values (Magurran, 2004; May, 1975; Melo, 2008; Oliveira, 2015). In addition, based on data from the considered forests remnants, we listed endemic and endangered tree/shrub species aiming to support the ongoing calling for conservational efforts in the Subtropical Atlantic Rainforest of Santa Catarina.
Methods
Study Area
The study area is inserted in the Coastal Mountain Range of Santa Catarina, Southern Brazil (Figure 1). The Subtropical Rainforest of Santa Catarina (Oliveira-Filho, 2015) state is placed between two different geomorphological units. The first is composed by the Serra do Tabuleiro/Itajaí complex, which is characterized by mountain ranges disposed in form of subplots with dissected relief, deep valleys with steep slopes, separated by sharped ridges; the second geomorphological unit is composed by the Delimitation of forest remnants of the Subtropical Rainforest of Santa Catarina according to SOS Atlantic Forest Foundation & INPE (2013), and the location of the 12 studies considered in this research.
According to the Köppen classification, the Subtropical Rainforest of Santa Catarina is influenced by two climate types: Cfa—humid mesothermal subtropical climate without dry season with a hot summer and Cfb—humid mesothermal subtropical climate without dry season with a mild summer (Alvares, Stape, Sentelhas, Gonçalves, & Sparovek, 2013). Due to environmental and altitudinal variations, the average annual temperature ranges from 11℃ to 20℃. Rainfall patterns may vary according to the altitude, ranging between 1,100 and 1,300 mm in the northern portion of the state (Pandolfo et al., 2002).
Data Collection
Number of Sampled Individuals (
We classified the conservation status of the vegetation of each study based on the description provided by the author(s). We defined three categories: (a)
We verified the patterns of distribution of species abundance (PDSA) through the Whittaker’s diagrams (Magurran, 2004). The similarities or differences among PDSA were tested by the Kolmogorov–Smirnov test for two samples, with α = .05 (Sokal & Rohlf, 1995). The Whittaker’s diagram is a useful tool to analyze PDSA in biological communities, such that contrasting patterns of species richness and vegetation uniformity may be addressed (Krebs, 2014; Magurran, 2004; Melo, 2008).
For the purpose of comparing the species richness of the studies, we constructed rarefaction curves using the Mao Tau method (Colwell, Mao, & Chang, 2004). We opted by the individual-based rarefaction, as multiple comparisons could be influenced by the tree density of each area (Gotelli & Colwell, 2001).
We estimated the
We investigated the relation between species diversity and the abundance of dominant species using Pearson’s correlation coefficient (
To support the necessity of directing efforts towards the conservation of the studied area, we listed the tree/shrub species recorded in the 12 studies and classified them according to their endemism to Brazil and to the Brazilian Atlantic Forest using information from
Results
We found similar patterns of species richness among the study areas (Figure 2). According to the Whittaker’s diagram, the community sampled by Maçaneiro et al. (2015) presented greater uniformity (less inclined curve) and greater species richness (more extended curve) when compared with the other studies (e.g., Citadini-Zanette, 1995; Colonetti et al., 2009; Ghoddosi, 2005; Martins, 2005; Sevegnani, 2003; Vibrans, 1999). The PDSA found in Maçaneiro et al. (2015) was significantly different (Kolmogorov–Smirnov, Whittaker’s diagram showing the abundance ( Individual-based rarefaction curves built by Mao Tau’s method, with their respective confidence intervals, for different studies conducted in the Subtropical Rainforest of Santa Catarina, Southern Brazil.

In the diversity profiles (Figure 4), we observed that species diversity varied among sites. Even though Maçaneiro et al. (2015) presented greater species diversity than other studies (e.g., Colonetti et al., 2009; Ghoddosi, 2005; Sevegnani, 2003; Vibrans, 1999), its diversity profile overlapped with the diversity profile of other sites (e.g., Emerich, 2009; Iza, 2002; Martins, 2005, 2010; Negrelle, 2006; Silva, 2006; Vibrans, 1999), suggesting that these sites are Diversity profiles build using Rényi’s series for different studies conducted in the Subtropical Rainforest of Santa Catarina, Southern Brazil. For the parameter α = 0, 
We found strong and highly significant correlations ( Relation between species diversity (
Among the 366 tree/shrub species registered in the compiled studies (Appendix), we detected three species classified as
Discussion
The tree species diversity of well-conserved sites in the Brazilian Atlantic Forest is not always superior to the diversity of less conserved areas in the same region—the species diversity of the RBMA (modified old-growth forest) is similar to secondary forests with different conservation status. However, it is important to highlight that this conclusion is based solely on tree species diversity with dbh ≥ 5.0 cm. Most likely, if other components were to be considered, such as understory plants, epiphytes and lianas, the species diversity would be greater in more conserved sites (Gasper et al., 2014; Leite & Klein, 1990). This hypothesis would be corroborated by studies contemplating various groups of plants using quantitative data collected in sample plots, instead of studies based solely on species checklists.
The translation of forest data into metrics of species diversity depends on the level of uniformity of the vegetation or, still, on the adopted diversity index. Despite the intrinsic characteristics of diversity indices regarding the weight given to rare and dominant species (Buckland et al., 2011; Hurlbert, 1971; May, 1975; Melo, 2008), our study brought evidence that
Our results revealed that PDSA are influenced by dominant species, such as the palm
In addition to the conservation status of the vegetation, the uniformity of populations might explain the similarities (or differences) in PDSA (Magurran, 2004). According to Melo (2008), communities with greater uniformity will present greater species diversity—dominant species have less chance to be observed. In less uniform communities, the species diversity will always be lower (Melo, 2008).
Even though species diversity is not always related to conservation status, the Subtropical Rainforest of Santa Catarina deserves attention regarding conservational efforts. Our study pointed a significant amount of endemism—46.4% of the listed species occur exclusively in the Atlantic Forest and 35.8% of the species are endemic to Brazil. The Subtropical Rainforest of Santa Catarina is inserted in the Serra do Mar endemism center (Silva & Casteleti, 2003), and the aforementioned statistics seem to support this fact. Our results add dimension to the findings of Rezende, Oliveira-Filho, Eisenlohr, Kamino, and Vibrans (2014), who pointed that ∼72% of Santa Catarina’s tree species have restrict geographical distribution (see also Oliveira et al., 2016). The species records summarized in our study corresponds to 65% of the species recorded by the Forest and Floristic Inventory of Santa Catarina, a systematic regional scale survey conduct in 418 sample plots (0.4 ha) among the state (Gasper et al., 2014). Therefore, these areas are relevant for conservation because they support populations of endemic species, including those registered in the IUCN Red List (IUCN, 2003; e.g.,
Implications for Conservation
Despite the fact that the species diversity of well-conserved forests may be inferior to the diversity of less conserved ones, such descriptor could be adopted for selecting priority areas for conservation in the neotropics (Gibson et al., 2011). Although, issues like those addressed in this study should be considered. In communities in which species diversity might not be the most adequate descriptor, the PDSA should be carefully analyzed. Facing the few studies regarding the Brazilian Subtropical Rain Forest, new studies, with similar approach, could concentrate efforts in investigating species diversity—especially PDSA—in different successional stages and environments, using a standardized sampling methodology to allow comparisons among sites.
Finally, we will try to conciliate the categories of
We conclude that conservation policies should be elaborated for the Brazilian Subtropical Rain Forest remnants, taking the example of the new forest policy of Santa Catarina state, which is grounded on the protection and management of secondary forests (Vibrans & Beilfuss, 2013). Facing the expressive (∼29%) native forestland cover of Santa Catarina (Vibrans, McRoberts, Moser, & Nicoletti, 2013), areas destined for biological conservation are mandatory, and there are no reasons for having a single RBMA in the state. Secondary forests also deserve attention because of the environmental services they perform. By these reasons, we encourage the establishment of new RBMAs, which will call for attention to the importance of biological conservation as a whole.
Appendix. List of the Native Tree/Shrub Species Recorded in Different Studies Conducted in the Subtropical Rainforest of Santa Catarina, Brazil
Footnotes
Acknowledgments
We are grateful to Luiz Henrique da Silva for reviewing the English language of the manuscript.
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: We are grateful to
