File Name: species diversity in ecological communities historical and geographical perspectives .zip
Species diversity, community structure and ecological traits of trees in an upper montane forest, southern Brazil. Upper montane ecosystems in Brazil are little known, and their structural and functional aspects poorly understood. Our goals were to describe tree species diversity and community structure, and to characterize tree species in relation to their ecological traits, phytogeographic history and conservation status in an upper montane araucaria forest remnant.
Species interactions are responsible for many key mechanisms that govern the dynamics of ecological communities. Variation in the way interactions are organized among species results in different network structures, which translates into a community's ability to resist collapse and change.
Species diversity, community structure and ecological traits of trees in an upper montane forest, southern Brazil. Upper montane ecosystems in Brazil are little known, and their structural and functional aspects poorly understood.
Our goals were to describe tree species diversity and community structure, and to characterize tree species in relation to their ecological traits, phytogeographic history and conservation status in an upper montane araucaria forest remnant. A total of 26 species belonging to 18 families were found in a 1-hectare permanent plot. The tree community mainly comprised trees with diameters of less than 20 cm and heights of between 6.
Drimys angustifolia and Myrceugenia regnelliana had the highest importance values. Most species were shade tolerant while most individuals were pioneers. Most species and individuals presented zoophily and zoochory. Most sampled species and individuals were related to araucaria forests. Seven species are threatened to some degree while one species, Crinodendron brasiliensis , besides threatened, is also endemic to the region. The presence of endemic and endangered species demonstrates that the studied area serves important conservation purposes.
Furthermore, the present study demonstrates the important role that upper montane regions have for conservation and describes the structural patterns of still poorly studied habitats, reinforcing the importance such systems have in maintaining species diversity at high elevations.
Understanding aspects related to diversity, forest community structure and dynamics are essential for supporting conservation policies and monitoring biodiversity Brito et al. Also, diversity-related aspects, such as species ecological traits and phytogeographic history, are key to comprehending ecological and organizational processes of plant communities.
Thus, combining information about diversity, structure and ecological traits may result in a better understanding of ecological systems than evaluating this information separately. However, baseline studies on diversity and structure are still lacking to properly characterize Brazilian ecosystems, especially those located in regions that are difficult to access, such as montane environments in southern Brazil.
Montane environments occur globally, usually above m a. Meybeck et al. Of all tropical forests, these environments are among the most poorly known and most threatened, and usually have high levels of endemism Gentry In subtropical Brazil, araucaria forests mixed rainforests occur mainly on the southern Brazilian plateau Veloso et al. At higher altitudes above m a. Processes and patterns that generate and maintain the biodiversity of Brazilian upper montane systems above 1, m a.
Therefore, considering the idiosyncrasies of upper montane ecosystems, the high levels of endemism, the threats and the need to increase knowledge about these systems, our objectives were 1 to describe the species diversity and community structure of trees, and 2 to characterize species in relation to their ecological traits, phytogeographic history migration routes and conservation status, in a permanent plot in an upper montane araucaria forest remnant.
The park protects high-altitude grasslands, mixed rainforest araucaria forest and subtropical rainforest, all belonging to Atlantic Forest domain Veloso et al. At higher elevations, the climate between and , recorded by the nearest weather station ca.
The average minimum temperature for the coldest month July was 6. The implemented methodology more info at: Fernandes et al. This study was conducted in the plot TN, in Module 1. The vegetation is characterized as upper montane araucaria forest and was possibly influenced by cattle until , when the area was protected. There are, however, reports of cattle influencing the area after it was protected. In general, soils in this region are shallow and usually Cambisols and Litholic Neosols Higuchi et al.
The plot has an average inclination of ca. To describe the species diversity and community structure, a 1-hectare permanent plot was built from a central line m long; permanent pickets were placed every 10 m.
The line was set at a point with a known altitude in this case 1, m a. Data collection of community structure followed the methodology in Castilho et al. We measured diameter at breast height DBH - 1. Two bands 2 and 3 were delimited upstream and downstream on both sides of the central line.
Each band was 10 m wide and m long 0. The total sampling area was 1 ha 0. For this study, the area within each demarked picket was considered a subplot, totaling 25 subplots of 10 x 20 m. To have a better understanding of the studied system, we characterized species in relation to their ecological traits, phytogeographic history and conservation status.
We classified the species into ecological groups of vertical distribution, light requirement, pollen and diaspore dispersal and phytogeographic history. The classification of each species into these groups was based on observations during fieldwork from to , scientific literature and consultations with specialists.
To determine diaspore dispersal strategy, species were grouped into categories based on diaspore morphology Pijl The latter group was further classified into two subgroups based on diaspore size and color Hoffmann et al.
Dispersal process studies are advisable to confirm such conjectures. We only focused on species with some degree of extinction risk, i. We used descriptive statistics to describe community structure and ecological characteristics.
We used rarefaction curves to visualize the completeness of sampling and extrapolate species richness in our phytosociological subplots Chao et al. Curves were extrapolated up to double our sample size. We sampled 1, trees 1, alive and 81 dead standing belonging to 26 species within 20 genera and 18 families one fern, two gymnosperms and 23 angiosperms Tab.
The most representative family was Myrtaceae seven spp. The most representative genus was Myrceugenia six spp. These species are among the five with highest values of density and frequency.
Only I. The total basal area was Decreasing order of IV alive individuals , followed by dead trees. The average diameter value was In relation to the frequency distribution of height classes, the average value was 7. Fifty percent of sampled individuals were between 6.
Dicksonia sellowiana was the most abundant small tree species nine individuals , M. Araucaria angustifolia was the only species considered as emergent and had 60 sampled individuals. Tree ferns were not included in the pollen transport and dispersal categories. Standing dead individuals were left out of this analysis.
The colors white, beige and yellow were predominant Tab. S1 in supplementary material. Only A. Apart from A. The true diversity of the sampled permanent plot is 10 species. The group of dead trees ranked fifth for the importance value 6.
Seven species Araucaria angustifolia is considered critically endangered in Santa Catarina State Consema , endangered in Brazil Brasil and classified as critically endangered on the world list Thomas Dicksonia sellowiana is considered critically endangered in Santa Catarina State Consema and endangered in Brazil Brasil Podocarpus lambertii is classified as endangered in Santa Catarina State Consema Myrceugenia miersiana and M.
This pattern of few dominant species and several subdominant to rare species is commonly found in araucaria forests e. The five most important species in this study D. Martins-Ramos et al. Among the surveyed families, Myrtaceae had the highest number of species. This family, in particular Myrceugenia , contributes the most species for the tree component in araucaria forests, including those from upper montane regions Klauberg et al. About half of all Myrceugenia species that occur in Brazil are found in araucaria forests in Santa Catarina State Gasper et al.
The tree fern D. However, although D. This fact could be related to the humidity conditions of the area, since this species prefers sites with elevated levels of humidity and shade Sehnem , such as valleys and south-facing slopes. However, this value is inferior compared to other studies carried out in similar systems e. Higuchi et al. Moreover, the historical exploration of the area must also be taken into consideration because constant interventions in the understory, such as cattle grazing, can cause losses in total diversity of the community Vibrans et al.
We did not observe a continuous strata of emergent araucaria trees in the studied stand, which is commonly attributed to araucaria forests Souza Moreover, the high number of dead standing individuals leads to gaps that allow more sunlight to reach the forest floor. From a successional perspective, this could be indicative of an advanced stage of forest development Budowisk Additionally, pioneer trees species, such as A. Regarding pollen transport and seed dispersal, animals seem to play an important role for both processes in the studied area.
The majority of surveyed species and individuals have zoophilous pollen dispersal and seeds dispersed primarily by animals. These mechanisms underlie the transmission of genetic information, population growth, and migration of plant species Kuparinen et al. These characteristics tend to attract small animals, such as insects, especially bees, wasps and beetles Heithaus ; Somavilla et al.
These values match other studies in upper montane araucaria forests e. In this context, A. Moreover, araucaria diaspores are available during unfavorable seasons i. The predominance of zoochorous species for both pollen transport and seed dispersal reinforces the role of animal-plant interactions for the maintenance of these systems.
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Publications of Michael L. Species diversity. What accounts for the number of species that exist? The following works present a basic, continent-scale, mathematical theory of diversity as a process, a process resulting from the differential equations of speciation and extinction. They identify area e. They predict several patterns of diversity with area, patterns that have proved accurate in the decades since the theory first emerged. They predict long-term equilibria actually steady states in diversity.
Skip to search form Skip to main content You are currently offline. Some features of the site may not work correctly. DOI: In this essay, I argue that the seemingly indestructible concept of the community as a local, interacting assemblage of species has hindered progress toward understanding species richness at local to regional scales.
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