Estrutura, composição e diversidade em florestas alagáveis de várzea de maré e de igapó e suas relações com variáveis edáficas e o período de inundação no Amapá, Amazônia oriental, Brasil

The objective of this study was to evaluate ecological and phytosociological patterns in flooded forests of várzea and igapó under different inundation regimes and their relationships with environmental variables, especially soil, in eastern Amazonia, Amapá, Brazil. All live trees with diameter at breast height (DBH) ≥ 10 cm were documented. A total of 26 100 x 100 m 1-ha plots were inventoried, distributed in 13 hectares within each forest typology. Gradient analysis, using both principal components analysis and canonical correspondence analysis, were sufficient to explain associations of plots and the distribution of species. Above ground biomass was evaluated using an allometric model already tested in humid forests, which considers wood density (p), height (H), and basal area (BA). In the 26 hectares sampled a total of 10,575 trees pertaining to 343 species, 172 genera and 49 families were registered, with mean wood density of 406.73 ± 61.27 trees ha -1 and mean basal area of 27.2 ± 11.13 m 2 ha -1 . Fabaceae, Arecaceae, Malvaceae, Meliaceae and Rubiaceae were the most important in várzea, together accounting for 74.76% of the family importance value index (FIVI%). In igapó, Fabaceae, Lecythidaceae, Euphorbiaceae, Malvaceae and Arecaceae stand out, accounting for 57.05% of the family importance value index (FIVI%). There were significant differences among forest types in regards to the mean number of individuals, species, diversity and height. However, they did not significantly differ in mean equitability, diameter, dominance and basal area. In igapó, acidity, aluminum, inundation regime, potassium and sand influence the distribution of species, in decreasing order of significance. In várzea, the associations of species with environmental variables showed association with cation exchange capacity, base saturation, inundation regime, potassium and antagonistically with silt, calcium, phosphorous and pH. Estimated biomass for each ecosystem showed practically the same mean (198.56 Mg/ha -1 ). In igapó the largest amplitude was 326.83 Mg ha -1 and for várzea, 272,12 Mg ha -1 . The inundation regime had a mean of 61±25,69 days/year and 21±1,33 days/year in igapó and várzea respectively. In várzea, the plot with least biomass was positively related with the duration of inundation. In igapó, was negatively related with pH and the silt fraction. In general, biomass showed little relation with edaphic variables in both environments. In conclusion, while hydro- edaphic variables characterize differences in the environmental gradient, these are poorly reflected in the distribution of species, which basically respond to duration of inundation and soil acidity.O objetivo deste estudo foi avaliar os padrões ecológicos e fitossociológicos em florestas alagáveis de várzea e igapó sob diferentes regimes de inundações e suas relações com variáveis ambientais, especialmente solo no Estado do Amapá, Amazônia oriental, Brasil. Foram registrados todos os indivíduos arbóreos, vivos, com diâmetro à altura do peito (DAP) ≥ 10 cm. Inventariou-se 26 parcelas de 100 x 100 m (1 ha cada), distribuídas em 13 hectares em cada tipologia florestal. As análises de gradientes, realizadas por meio de análise de componentes principais e análise de correspondência canônica foram suficientes para explicar a associação das parcelas e a distribuição das espécies. Optou-se por avaliar a biomassa acima do solo através do modelo alométrico já testado em florestas úmidas em que considera as variáveis de densidade da madeira (p), altura (H) e a área basal (AB). Registrou-se 10.575 árvores pertencentes 343 espécies, 172 gêneros e 49 famílias, com densidade média de 406.73 ± 61.27 árvores ha -1 e 27.2 ± 11.13 m 2 ha -1 de área basal nos 26 hectares amostrados. Fabaceae, Arecaceae, Malvaceae, Meliaceae e Rubiaceae, foram mais importantes na várzea, juntas responderam por 74.76 do índice de valor de importância familiar (IVIF%). Para o igapó destacaram-se Fabaceae, Lecythidaceae, Euphorbiaceae, Malvaceae e Arecaceae, juntas responderam por 57.05 do índice de valor de importância (IVIF%). Houve diferença significativa entre os dois tipos de floresta em termos de número médio de indivíduos, espécies, diversidade e altura. No entanto, não diferiram significativamente para média de equabilidade, diâmetro, dominância e área basal. No igapó, acidez, alumínio, regime de inundação, potássio e areia influenciaram a distribuição das espécies, em ordem decrescente de significância. Na várzea, a associação das espécies com as variáveis ambientais mostraram associação com a capacidade de troca catiônica, saturação de bases, regime de inundação, potássio e, antagonicamente a silte, cálcio, fósforo e pH. A biomassa estimada para os dois ecossistemas, apresentaram praticamente a mesma média (198,56 Mg/ha -1 ). No igapó a amplitude maior foi de 326,83 Mg ha -1 e na várzea foi 272,12 Mg ha -1 . O regime de inundação teve média de 61±25,69 dias/ano e 21±1,33 dias/ano, respectivamente, no igapó e na várzea. Na várzea a parcela com menor biomassa foi positivamente relacionada com o período de inundação. No igapó foi negativamente relacionada com pH e fração de silte. No geral, a biomassa apresentou pouca relação com as variáveis edáficas nos dois ambientes. Conclui-se que por mais que as variáveis hidroedáficas caracterizam as diferenças no gradiente ambiental, estas apresentaram pouco reflexo na distribuição das espécies e, estas, respondem basicamente ao período de inundação e a acidez do solo

Diversidade florística em dois trechos de Floresta Secundária na Amazônia Oriental, estado do Amapá.

The increasing importance of secondary forests all over the world alerts us to the urgent need to understand the biophysical and social underlying factors that affect its regeneration after the abandonment of agricultural practices and natural disturbances. In the state of Amapá, studies related to the structure of secondary forests are still scarce. Therefore, this article aims to characterize the floristic composition and structure in two stretches of secondary forest in the eastern Amazon, state of Amapá. For the floristic and phytosociological study of tree species, 10 plots of 10 x 100 m (1.0 ha) were established: five plots in the community of São Francisco do Iratapuru and five plots in the community of Santo Antônio waterfall, totaling half a hectare (0,5 ha) in each area. In all plots, subjects with diameter at breast height (DBH) ≥ 5 cm were considered. In total, 1,183 subjects were sampled in the two stretches of forest. In stretch 01, 565 subjects belonging to 74 species, 55 genera and 33 families were recorded. In stretch 02, 618 subjects belonging to 26 species, 23 genera and 15 families were recorded. The Shannon diversity index (H'), estimated for stretch 1, was 3.52; and for stretch 2 (2.23). The two studied stretches, despite being registered at the same age, showed significant difference in the species richness, which is the major factor for diversity differences, resulting in low similarity between the studied forests.O reconhecimento do papel das florestas secundárias na manutenção estrutural e funcional da biodiversidade em nível de paisagem e seu potencial ecológico passa pela intensificação dos estudos sobre sua dinâmica, conhecimento florístico e das condições atuais em que elas se encontram em diversas paisagens antropizadas. Este artigo objetivou caracterizar a diversidade florística em dois trechos de floresta secundária na Amazônia oriental, estado do Amapá. Para o estudo florístico e fitossociológico das espécies arbóreas, foram estabelecidas 10 parcelas de 10 x 100 m (1,0 ha): cinco na comunidade de São Francisco do Iratapuru e cinco na comunidade de Santo Antônio da cachoeira, totalizando meio hectare (0,5 ha) em cada área. Em todas as parcelas foram mensurados indivíduos arbóreos com diâmetro a 1,30 cm do solo (DAP) ≥ 5 cm. No total, foram amostrados 1.183 indivíduos nos dois trechos de floresta. No trecho 1 foram registrados 565 indivíduos, distribuídos em 74 espécies, 55 gêneros e 33 famílias. No trecho 2 foram registrados 618 indivíduos, distribuídos em 26 espécies, 23 gêneros e 15 famílias. O índice de diversidade de Shannon para o trecho 1 foi de H’=3,52 e para o trecho 2 foi de H’=2,23. Os dois trechos estudados, embora registrados com a mesma idade, apresentaram expressiva diferença na riqueza de espécies, sendo este o fator preponderante para diferenças de diversidade, culminando com a baixa similaridade entre as florestas estudadas.

COMPOSITION AND STRUTURE OF DENSE OMBROPHYLOUS FOREST IN THE EXTREME NORTH OF THE STATE OF AMAPÁ, BRASIL

Neste artigo é apresentado a fitossociologia e florística de um fragmento de Floresta Ombrófila Densa no extremo Norte do Brasil, com árvores de CAP ≥ 33cm. Os dados foram coletados em 17 parcelas de 20m x 100m distribuídos aleatoriamente na área de estudo. Foram registrados 1804 indivíduos distribuídos em 30 famílias, 70 gêneros e 93 espécies. As famílias Fabaceae e Lauraceae destacaram-se em todos os parâmetros fitossociológicos analisados, assumindo a primeira e segunda posição em riqueza, densidade, dominância e frequência. Protium pubescens destacou-se como a espécie mais importante com 24,59 de IVI, como também a que apresentou o maior número de indivíduos na comunidade (144), seguida de Dipteryx odorata com 13,99 de IVI e 43 indivíduos e Hymenaea courbaril, com 11,45 de IVI e 29 indivíduos.Palavras-chave: florística, fitossociologia, Amazônia.This paper presents the floristic and phytosociological fragment of a Tropical Rain Forest in the extreme North of Brazil, with trees CBH ≥ 33cm. Data were collected on 17 plots of 20m x 100m randomly distributed in the study area. We recorded 1804 individuals belonging to 30 families, 70 genera and 93 species. Lauraceae and Fabaceae families stood out in all phytosociological parameters analyzed, assuming the first and second position in richness, density, dominance and frequency. Protium pubescens stood out as the most important species with 24.59 of IVI, as well as the one with the largest number of individuals in the community (144), followed by Dipteryx odorata 13.99 of IVI and 43 individuals and Hymenaea courbaril, with 11,45 of IVI and 29 individuals.Keywords: Floristic; Phytosociology; Amazon

COMPOSITION AND FLORISTIC DIVERSITY OF A PATCH OF THE UPLAND IN SOUTHWESTERN AMAPÁ, EASTERN AMAZON, BRAZIL

O objetivo do presente trabalho foi determinar a composição e a diversidade florística de um trecho de floresta de terra firme no Sudoeste do Estado do Amapá, Amazônia Oriental, Brasil. Visando com este estudo, ações de conservação florestal. Para o levantamento, foram distribuídas aleatoriamente 10 parcelas de 10mx100m, perfazendo um hectare. Com auxílio de fita métrica e uma haste de 6m, dividida de um em um metro, foram tomados dados de altura e DAP≥10cm (Diâmetro a Altura do Peito) de todos os indivíduos arbóreos vivos. Neste trabalho, foram registrados 462 indivíduos, pertencentes a 33 famílias e 123 espécies. As espécies com maiores valores de importância (VI) foram, Sclerolobium densiflorum Geissospermum sericeum, Pouteria decorticans, Pentaclethra macroloba e Rinorea racemosa. Na área amostrada, foram encontradas espécies com grande valor comercial e presentes na lista de espécies ameaçadas, dentre elas: Aniba rosaedora (Pau rosa), Vouacapoua americana (Acapú) e Bertholethia excelsa (Castanheira). A presença das referidas espécies é um indicativo de qualidade e conservação ambiental.Palavras-chave: Vegetação, Biodiversidade, fitossociologia.The purpose of this study was to determine the composition and floristic diversity of a stretch of upland forest in southwestern Amapá State, eastern Amazon, Brazil. Aiming to this study, the actions of forest conservation. For the survey, 10 parcels were randomly distribuited in 10mx100m, making an hectare. Along with a tape and a six-meter-long rod, divided into meter by meter data and DBH≥10cm (Diameter at Breast Height) of all living individual trees were taken. In this study, 462 individuals belonging to 33 families and 123 species were recorded. The species with the highest importance values (IV) were, Sclerolobium densiflorum, Geissospermum sericeum, Pouteria decorticans, Pentaclethra macroloba and Rinorea racemosa. In the sampled area, species with high commercial value and present in the list were found of endangered species, among them: Aniba rosaeodora (Pau rosa), Vouacapoua americana (Acapu) and Bertholethia excelsa (Chestnut). The presence of such species is an indicator of quality and environmental conservation.Keywords: Vegetation; biodiversity; phytosociology

Composição, estrutura e diversidade florística em floresta ombrófila densa na Amazônia Oriental, Amapá, Brasil

This study aims to evaluate the phytosociology and floristic composition of tree species in the eastern Amazon, at the Iratapuru River Sustainable Development Reserve (RDS), State of Amapá. Fouteen quarters with dimensions of 100 m x 100 m were randomly inventoried, and 50 sub-plots of 10 m x 20 m were established. In each sub-plot all living individuals were sampled, being taken from the height data and DAP (breast height diameter) for tree species ≥ 10 cm. A total of 5,233 individuals belonging to 33 families and 184 species were registered. The families with the largest number of species were Fabaceae (32), Lauraceae (17), Sapotaceae (12), Moraceae (10), Lecythidaceae (8) and Annonaceae (8). The six most abundant families (18.18% of total families) in the present study were responsible for more than half (57.92%) of the total number of species. The floristic structure of the area studied was diverse, with species of varied interests, including: medicinal, timber and oil-producing. © 2015 Eduem - Editora da Universidade Estadual de Maringa. All rights reserved

Composition, diversity, and structure of tidal “Várzea” and “Igapó” floodplain forests in eastern Amazonia, Brazil

The objective of this study was to evaluate the composition, diversity, and structure of tidal “Várzea” and “Igapó” forests in eastern Amazonia, Amapá, Brazil. All live tree individuals with diameter at breast height (dbh) ≥10 cm were registered. A total of 130 plots measuring 10 × 100 m were inventoried, distributed among 13 ha in each of the two forest typologies. A total of 10,575 trees were reported, belonging to 343 species, 172 genera, and 49 families. For all 26 ha sampled, mean tree density was 406 ± 61.27 trees ha−1 and mean basal area was 27.2 ± 11.13 m2 ha−1. Fabaceae, Arecaceae, Malvaceae, Meliaceae, and Rubiaceae were the most important families in tidal “Várzea”, together accounting for 74.76 % of the family importance value index (FIVI %). In “Igapó”, the most important families were Lecythidaceae, Euphorbiaceae, Malvaceae, and Arecaceae, which together accounted for 57.05 % of the family important value index (FIVI %). Smaller diameter trees measuring between 10 and 30 cm dbh dominated the landscape, accounting for 75.52 % of all individuals sampled. In general, 80 % (8285) individuals were under 24 m in height, while only 1.32 % of trees (140) reached heights above 34 m. There was evidence for statistically significant mean differences among tidal “Várzea” and “Igapó” with regard to the number of individuals, species, diversity, and tree height. However, no mean differences were detected for equitability, dbh, dominance, and basal area. Compositional patterns showed low similarity between the evaluated areas, indicating the existence of phytogeographic pattern based on species distribution. © 2016, Botanical Society of Sao Paulo

Padrão de distribuição espacial e estrutura diamétrica de Protium Burm. F. na reserva de desenvolvimento sustentável do rio iratapuru, Amapá, Brasil

The present work aims to determine the spatial distribution pattern of Protium Burm. f and the diametric structure of these species in a dense tropical submontane rainforest along the Sustainable Development Reserve (SDR) of the Iratapuru river. The area of study was divided into three plateau compartments called Mane Preto Sierra, Banco Grande Sierra and Alaska Sierra. In each plateau compartment it was settled a single area transect with 1,000 x 20 m, where DAP ≥ 10 cm of the entire Protium population within the transects was measured. The data was processed in the specific software Mata Nativa 2. There were inventoried Protium tenuifolium, Protium altsoni, Protium polybotryum subsp. blackii and Protium paniculatum var. riedelianum. Most individuals concentrated in smaller diametric classes, decreasing progressively to a lesser extent in larger classes. It can be concluded that the population has medium size and its vertical structure is characterized by the presence of three strata, however, its phytocenoses is defined by two clear constants: the first groups individuals of up to 15 m of height and forms the uniform and dominant stratum; the second is composed by emerging up to 35 m high and whose diameter structure shows a population in dynamic balance. © 2018, Eduem - Editora da Universidade Estadual de Maringa. All rights reserved

MORFO-ANATOMIA COMPARATIVA DO SISTEMA REPRODUTIVO DE Urospatha SCHOTT (ARACEAE) OCORRENTE NO ESTADO DO AMAPÁ, BRASIL

The genus Urospatha Schott, an aquatic and perennial herb occurring in “várzea” and “igapó” areas. Describe the inflorescence morpho-anatomy of the species found in the state of Amapá, to identify the present types of secretory structures and to verify the chemical nature of the secretion. Adult and fertile Urospatha specimens were collected in the Bailique Archipelago; in the municipalities of Calçoene; Mazagão; Porto Grande and Macapá. There were performed morpho-anatomical studies, using scanning electron microscopy techniques and also histochemical tests. Urospatha species present terminal inflorescence with flowering throughout the whole year; the spadix has hermaphrodite, tetramerous flowers. The tepals have uniseriate and heterodimensional epidermis, with thick-walled cells with thin and striated cuticle, secretory papillae and stomata. The androecium in adaxial and abaxial regions and right below epidermis occurs in parenchymal cells, and in lower regions occurs the presence of idioblasts carriers of raphides and druses that are more typical in the region close to the anthers. The ovary has/ an uniseriate epidermis with two or three anatropous ovules. The stigma has simple epidermis, papillose and parenchyma with raphides idioblasts. In the adaxial region of the spathe occurs uniseriate epidermis with heterodimensional cells with lignified walls and thin cuticle, and uniseriate hypodermis. The peduncle presents an uniseriate epidermis with lignified walls, thin cuticle, lenticels, stomata, and collenchyma just below the epidermis, with collateral vascular bundless and aerenchyma. The results of this work, especially the morphological and anatomical data, cannot differentiate Urospatha species found in the state of Amapá, because they present the same morpho-anatomical pattern for their floral structure.Keywords: Araceae, anatomy, inflorescence, morphology, Urospatha.O gênero Urospatha Schott é uma erva aquática e perene que ocorre nas áreas de várzea e igapó. O trabalho descreve a morfoanatomia da inflorescência das espécies encontradas no estado do Amapá, identifica os tipos atuais de estruturas secretoras e verifica a natureza química da secreção. Amostras de Urospatha adultas e férteis foram coletadas no arquipélago do Bailique; nos municípios de Calçoene; Mazagão; Porto Grande e Macapá. Foram realizados estudos morfoanatômicos, utilizando técnicas de microscopia eletrônica de varredura e também testes histoquímicos. As espécies de Urospatha apresentam inflorescência terminal com floração durante todo o ano; a espadice tem flores hermafroditas e tetrâmeras. Os tépals têm epiderme unisseriada e heterodimensional, com células de paredes espessas, com cutícula fina e estriada, papilas secretórias e estômatos. O androceu nas regiões adaxial e abaxial e logo abaixo da epiderme ocorre nas células parenquimatosas, e nas regiões inferiores ocorre a presença de idiosblastos portadores de ráfides e drusas mais típicos da região próxima às anteras. O ovário tem uma epiderme unisseriada com dois ou três óvulos anátropos. O estigma tem epiderme simples, papilose e parênquima com ráfides idiosblastos. Na região adaxial da espata ocorre epiderme unisseriada com células heterodimensionais, com paredes lignificadas e cutícula fina e hipoderme unisseriada. O pedúnculo apresenta uma epiderme unisseriada com paredes lignificadas, cutícula fina, lenticelas, estômatos e colênquima logo abaixo da epiderme, com bundless vascular colateral e aerênquima. Os resultados deste trabalho, principalmente os dados morfológicos e anatômicos, não conseguem diferenciar as espécies de Urospatha encontradas no estado do Amapá, pois apresentam o mesmo padrão morfo-anatômico para sua estrutura floral.Palavras-chave: Araceae, anatomia, inflorescência, morfologia, Urospatha

Rarity of monodominance in hyperdiverse Amazonian forests.

Tropical forests are known for their high diversity. Yet, forest patches do occur in the tropics where a single tree species is dominant. Such "monodominant" forests are known from all of the main tropical regions. For Amazonia, we sampled the occurrence of monodominance in a massive, basin-wide database of forest-inventory plots from the Amazon Tree Diversity Network (ATDN). Utilizing a simple defining metric of at least half of the trees ≥ 10 cm diameter belonging to one species, we found only a few occurrences of monodominance in Amazonia, and the phenomenon was not significantly linked to previously hypothesized life history traits such wood density, seed mass, ectomycorrhizal associations, or Rhizobium nodulation. In our analysis, coppicing (the formation of sprouts at the base of the tree or on roots) was the only trait significantly linked to monodominance. While at specific locales coppicing or ectomycorrhizal associations may confer a considerable advantage to a tree species and lead to its monodominance, very few species have these traits. Mining of the ATDN dataset suggests that monodominance is quite rare in Amazonia, and may be linked primarily to edaphic factors