The Pantanal is subjected to a monomodal and predictable flood pulse of low amplitude which is the main driver of ecological processes and patterns of biodiversity in one of the largest wetlands in the world. Nevertheless, little is known about how the plant communities of this wetland respond to predicted climate changes. In this paper, we used tree-ring analyses of Vochysia divergens Pohl (Vochysiaceae), a light-demanding pioneer species that occurs in periodically or short-term flooded areas in the Cerrado and Pantanal. We evaluated the influence of precipitation and water level on the growth rates of this species, where it occurs, to determine how local climatic variables (precipitation and water level) influence tree growth and how a large-scale climatic driver in the tropical eastern Pacific (El Nin ˜o events) could affect both tree growth and local climate in the northern region of the Pantanal. The indexed tree-ring chronology of eight individuals had a significant relationship with annual precipitation (r = 0.22). Interannual variations of the water level did not affect tree growth. Sea surface temperature anomalies of the El Nin ˜o 1 ? 2 region lead to decreased precipitation in the northern region of the Pantanal, resulting in decreased diameter increments of V. divergens. Our results demonstrated the dendrochronological potential of V. divergens for analyzing climate-growth relationships for developing climate-sensitive proxies for reconstructing past climatic conditions.
RESUMO:Entre as savanas tropicais, o Cerrado apresenta maior diversidade de plantas com cerca de 12.000 espécies descritas. Considerado um dos hotspots mundiais de biodiversidade, o Cerrado vem sofrendo forte ameaça e o conhecimento dos padrões de distribuição vegetal em áreas com grande diversidade se torna imprescindível para a criação estratégias de conservação. O Parque Nacional da Chapada dos Guimarães (PNCG), localizado na área central do Cerrado, possui uma grande diversidade de ambientes devido às variações de altitude, sendo a tipologia mais representativa, a de Cerrado sensu stricto. Este trabalho teve como objetivo analisar a riqueza, diversidade e estrutura horizontal da comunidade arbórea desta tipologia. Para isto, foram alocadas 6 parcelas de 20 x 250 m (5000 m 2 ), em isolinhas, e amostrados todos os indivíduos com diâmetro a altura da base (DAB) ≥ 5 cm. Para verificação da suficiência amostral, utilizou-se o estimador não paramétrico de Jackknife, a diversidade foi estimada pelo índice de Shannon e de Simpson. Foram amostradas 100 espécies arbóreas distribuídas em 64 gêneros e 36 famílias botânicas. As famílias que mais contribuíram para a riqueza foram Fabaceae com 18 espécies, Myrtaceae com 7 espécies, Vochysiaceae e Apocynaceae com 6 espécies e Bignoniaceae com 5 espécies. Phytosociology of the cerrado stricto sensu community in the "Parque Nacional da Chapada dos Guimarães" ABSTRACT: Among the tropical savannas, Cerrado presentes greater diversity of plants with about 12.000 described species. The Cerrado biomeis considered one of the world's biodiversity hots pots and has come under strong threat, so the knowledge of plant distribution patterns in areas with high diversity is indispensable to create conservation strategies. The Chapada dos Guimarães National Park (CGNP), located in the central area of the Cerrado, has a large variety of environments due to variations in altitude, being the most representative type, the Cerrado sensu stricto. The objective of this study was to analyze the richness, diversity and horizontal structure of the arboreal community of this typology. To this, were allocated 6 plots of 20 x 250 m (5000 m 2 ), in isolines, and sampled all individual with diameter of the base height (DAB) ≥ 5 cm. In order to verify the sample sufficiency, we used the nonparametric estimator of Jackknife, diversity was estimated by Shannon and Simpson index. One hundred tree species distributed in 64 genera and 36 botanical families were sampled. The families who most contributed to the richness were Fabaceae with 18 species, Myrtaceae with 7 species, Vochysiaceae and Apocynaceae with 6 species and Bignoniaceae with 5 species. The arboreal community of Cerrado sensu stricto of the CGNP has density of 1.861,33 (± 719.93) individuals per hectare, and basal area of 15,14 (±7,01) m 2 ha -1. A group of 20 species represents 82.75% of all individuals and 80.79% of the basal area per hectare. The diversity of arboreal vegetation is 3,24 nats/individual by Shannon index, and 0,70 by Simpson ind...
Climatic factors can influence the establishment and growth of wood species, but little is known about the effect of these factors on monodominant communities in wetlands. Therefore, we asked how climatic factors, such as ENSO (El Niño-Southern Oscillation), precipitation and flooding, influence growth and establishment of the dominant species Erythrina fusca in the Pantanal. We determined the age of sampled individuals, the age of the population and evaluated the effects of climate on tree growth. We obtained samples for dendrochronological analyses using destructive (seven individuals) and non-destructive methods. We cross-dated and built a chronology, correlating results with climatic factors. We sampled 0.6 ha of the population and separated individuals into diameter classes to determine age based on diameter/age ratio obtained through dendrochronological analyses. We obtained a chronology with individuals up to 34 years old, while in the population sample, the oldest individual was 54 years old. The factors that influenced growth during the study period were precipitation (positive correlation) and El Niño (negative correlation). E. fusca individuals seem to grow more during the period of highest precipitation, and El Niño events reduce precipitation in the Pantanal, resulting in a decrease in the growth of E. fusca individuals. We detected a decrease of young individuals in the last nine years, which seems to be related to the decrease in minimum flood levels. This indicates a future decline in the number of individuals. These results allow us to propose measures to protect these monodominant formations, which mainly involve avoiding further anthropic activities, that could reduce flooding levels.
Understorey herbs form a diverse and understudied plant assemblage in tropical forests. Although several studies and research teams have long been dedicated to the study of this conspicuous vegetation component in Amazonia, no effort to unify the data has been undertaken to date. In contrast to trees and other life forms for which major data compilations already exist, a unified database dedicated to herbs is still lacking. Part of the problem is in defining what is a herb and how to effectively sample herb assemblages. In this article, we describe the database HERBase, an exhaustive compilation of published and unpublished data on herb inventories in Amazonia. We also describe the structure, functioning, and guidelines for data curation and integration in HERBase. We were able to compile information from 1381 plots from all six Amazonian geographic regions. Based on this dataset, we describe and discuss sampling and knowledge gaps, priority areas for new collections, and recommend sampling protocols to facilitate data integration in the future. This novel database provides a unique biodiversity data repository on understorey herbs that will enable new studies on community ecology and biogeography.
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