FITOSSOCIOLOGIA DE PLANTAS DANINHAS EM CULTIVO DE FEIJÃO-CAUPI NO SEMIÁRIDO MINEIRO

O presente trabalho teve como objetivo caracterizar a dinâmica da comunidade infestante de plantas daninhas em cultivo do feijão-caupi no semiárido mineiro. Os tratamentos consistiram na coleta das plantas daninhas aos 7, 14, 21, 28, 35, 42, 49, 56, 63 dias após a emergência (DAE), posteriormente foi feito o controle da comunidade infestante por capina mecânica. A coleta de plantas daninhas foi feita pelo método padrão do quadrado inventário, lançado aleatoriamente na área útil de cada parcela, recolhendo todas as plantas. Foram determinados o número de indivíduos por espécie em cada parcela e o número total por coleta. Após a identificação e contagem das espécies, foi realizado o cálculo das variáveis fitossociológicas: Frequência, Densidade, Abundância, Frequência relativa, Densidade relativa, Abundância relativa, Dominância relativa, Índice de valor de importância (IVI), Índice de valor de cobertura (IVC) e Índice de similaridade (IS). As espécies Portulaca oleracea, Amaranthus viridis e Sorghum bicolor apresentaram maiores valores de IVI. Foi possível afirmar que é alta a similaridade florística das espécies de plantas daninhas que ocorreram durante o ciclo do feijão-caupi. Quanto ao Índice de valor de Cobertura (IVC), destacaram-se as espécies Portulaca oleracea, Sorghum bicolor e Senna obustifolia. Palavras-chave: comunidade infestante; Vigna ungiculata; levantamento fitossociológico. Phytosociology of weeds in cultivation of cowpea in the semi-arid region of Minas Gerais ABSTRACT: The present work aimed to characterize the dynamics of the weed community in cultivation of cowpea in the semi-arid region of Minas Gerais. The treatments consisted of collecting the weeds 7, 14, 21, 28, 35, 42, 49, 56, 63 days after emergence (DAE); following each collection, the weed community was controlled by mechanical weeding. The collections were carried out using the standard method of the inventory square, randomly launched in the useful area of each plot, collecting all the plants. The number of individuals per species in each plot and the total number per collect were determined. After identifying and counting the species, the phytosociological variables were calculated: Frequency, Density, Abundance, Relative frequency, Relative density, Relative abundance, Relative dominance, Importance value index (IVI), Coverage value index (CVI) and Similarity Index (SI). The species Portulaca oleracea, Amaranthus viridis and Sorghum bicolor presented the largest IVI. It was possible to affirm that the floristic similarity of the weed species that occurred during the cowpea cycle is high. The species Portulaca oleracea, Sorghum bicolor and Senna obustifolia presented the highest CVI values. Keywords: infestant comunnity; Vigna ungiculata; phytosociological survey.

The global loss of floristic uniqueness

Regional species assemblages have been shaped by colonization, speciation and extinction over millions of years. Humans have altered biogeography by introducing species to new ranges. However, an analysis of how strongly naturalized plant species (i.e. alien plants that have established self-sustaining populations) affect the taxonomic and phylogenetic uniqueness of regional floras globally is still missing. Here, we present such an analysis with data from native and naturalized alien floras in 658 regions around the world. We find strong taxonomic and phylogenetic floristic homogenization overall, and that the natural decline in floristic similarity with increasing geographic distance is weakened by naturalized species. Floristic homogenization increases with climatic similarity, which emphasizes the importance of climate matching in plant naturalization. Moreover, floristic homogenization is greater between regions with current or past administrative relationships, indicating that being part of the same country as well as historical colonial ties facilitate floristic exchange, most likely due to more intensive trade and transport between such regions. Our findings show that naturalization of alien plants threatens taxonomic and phylogenetic uniqueness of regional floras globally. Unless more effective biosecurity measures are implemented, it is likely that with ongoing globalization, even the most distant regions will lose their floristic uniqueness.

Atlantic Forest meeting Cerrado: floristic, structure, and species distribution of an ecotonal tree community

We evaluated the floristic and structural composition of a tree community in an ecotone between Cerrado (cerradão) and Atlantic Forest (seasonal semideciduous forest) domains located in Porto Ferreira State Park (PFSP), southeastern Brazil. We compared the floristic relationships of this ecotone with those of previous surveys carried out on the same vegetation types and checked the species distribution among the Brazilian biomes. We sampled all living trees with PBH>10 cm in 64 10x10 m plots (0.64 ha), totaling 1,755 individuals belonging to 101 species and 37 families. The richest families were Myrtaceae (13 spp.) and Fabaceae (11 spp.), and Siparuna guianensis was the most abundant species (188 individuals). We reported two threatened species. A great number of species are widely distributed, occurring in different Brazilian biomes. Floristic similarity values were low among the selected studies, but our sampled community clustered with communities of cerradão and ecotone areas of previous surveys. Our results corroborate that ecotonal areas have great tree diversity and the predominance of widely distributed species. This fact, combined with the vegetation thickening verified through historical photographs, reinforces that the study area belongs to an under-changing ecotone.

Tree structure and diversity of a Humid Mountain Forest in the protected natural area La Martinica, Veracruz, Mexico

Tree structure and diversity at the protected natural area La Martinica, Veracruz, México. Introduction: The Humid Mountain Forest (HMF) has the largest number of plants per unit area, which vegetation grows in heterogeneous environmental conditions and has a high variation flora, physiognomy and structural. The conservation of the HMF is important due to the biodiversity it harbors and the environmental regulation services it provides. Objective: This work evaluated the effect of the direction of sun exposure (aspect) of the terrain and the density of the forest canopy (canopy opening type) on the structure and tree diversity in La Martinica Protected Natural Area, in Veracruz, Mexico. Methods: stratified sampling was performed in four aspects of the terrain and two canopy density conditions. In total, 25 20 x 25 m sampling units were considered (subdivided into 10 x 5 m units), in which the normal diameter (ND), total height and the largest and smallest diameters of the crown of the individuals with a ND ≥10 cm were registered. The diversity was estimated by means of rarefaction curves and the structure was analyzed through the importance value index and the forest value index. Results: We recorded 37 species belonging to 30 genera and 24 families, Zenithal and South aspects had the highest floristic similarity. Greater diversity was observed in the North aspect and in the Closed canopy. The tree species with the highest structural values were different between aspects and canopy types; Carpinus tropicalis presented the highest values in the Zenithal aspect, Lippia myriocephala in the East and South aspects, and Liquidambar styraciflua in the North. In both types of canopy Lippia myriocephala obtained the highest values in the Importance Value Index (IVI) and only Forest Value Index (FVI) in the Open canopy; Carpinus tropicalis reached a higher FVI in the Closed canopy. Conclusions: The tree structure was different in the four aspects studied, as well as in the two conditions of the canopy. The greatest difference in species composition and diversity was observed between the North and East aspects, of these, the North presented the highest richness values, equally frequent species and dominant species.

Assessment of the Soil Seed Bank Aiming at Transposition to Forest Regeneration in the Western Amazonia

This study evaluated the soil seed bank’s germination potential and density in five distinct environmental areas namely: a) regenerated forest, b) secondary forest, c) degraded pasture, d) Eucalyptus sp. plantation and e) fallow corn growing area, with a view to regenerate forests in Western Amazonia using tray germination methodology. We assessed floristic similarity and diversity using the Jaccard Similarity Index and the Shannon Diversity Index, respectively. We computed each species’ phytosociological parameters: density, frequency and importance value of each species. We recorded a total 3674 individuals from 51 species and 21 families. The families with the highest species richness were Asteraceae, Malvaceae, Cyperaceae and Poaceae that contributed to 43% of the total species observed. The most important species computed in the phytosociological analysis were Chamaesyce hirta, Corchorus aestuans, Cyperus iria and Chamaesyce prostrata. All species had a herbaceous life form, which in the literature, are considered weeds. We documented the largest number of individuals in the fallow corn growing area that had 3620 plants m-2 and the smallest number in the regenerated forest that had 183 plants m-2. We observed the greatest floristic similarity between the secondary forest and Eucalyptus sp. plantation (40%), and the greatest floristic diversity in the Eucalyptus sp. plantation (H '= 2.59 nats individual-1). In conclusion, the transposition of the soil seed bank is not recommended for forest regeneration and recovery in degraded areas due to massive weed predominance in the soil seed bank.

Measuring Alpha and Beta Diversity by Field and Remote-Sensing Data: A Challenge for Coastal Dunes Biodiversity Monitoring

Combining field collected and remotely sensed (RS) data represents one of the most promising approaches for an extensive and up-to-date ecosystem assessment. We investigated the potential of the so called spectral variability hypothesis (SVH) in linking field-collected and remote-sensed data in Mediterranean coastal dunes and explored if spectral diversity provides reliable information to monitor floristic diversity, as well as the consistency of such information in altered ecosystems due to plant invasions. We analyzed alpha diversity and beta diversity, integrating floristic field and Remote-Sensing PlanetScope data in the Tyrrhenian coast (Central Italy). We explored the relationship among alpha field diversity (species richness, Shannon index, inverse Simpson index) and spectral variability (distance from the spectral centroid index) through linear regressions. For beta diversity, we implemented a distance decay model (DDM) relating field pairwise (Jaccard similarities index, Bray–Curtis similarities index) and spectral pairwise (Euclidean distance) measures. We observed a positive relationship between alpha diversity and spectral heterogeneity with richness reporting the higher R score. As for DDM, we found a significant relationship between Bray–Curtis floristic similarity and Euclidean spectral distance. We provided a first assessment of the relationship between floristic and spectral RS diversity in Mediterranean coastal dune habitats (i.e., natural or invaded). SVH provided evidence about the potential of RS for estimating diversity in complex and dynamic landscapes.

Integrative assessment of the floristic diversity of Gentianaceae in an area of campo rupestre of the Espinhaço Range in the state of Bahia, northeastern Brazil

This study aimed to assess the diversity of species in the Espinhaço Range (ER), eastern Brazil, using as a model the diverse plant family Gentianaceae and focusing on the Parque Municipal de Mucugê—Projeto Sempre Viva (PMM), a conservation unit with predominance of “campo rupestre”. For this purpose, fieldwork expeditions were carried out between the years 2016–2018 along with a survey of species of this family recorded for this conservation unit in public databases. For comparative purposes, the listing of species from other five areas of the ER were also surveyed and we modeled the distribution of species endemic to these mountains, taking into account that they have their restrict distribution, high habitat specificity and importance to the ecosystem. The results indicated the presence of 33 species of Gentianaceae for the ER, eight of them occurring in the PMM. Comparatively, the results pointed to a greater floristic similarity between the PMM, Pico das Almas and Catolés, due to the presence of seven common species. Predictive distribution modeling supports high endemicity of the analyzed species, given their low environmental suitability outside the ER. The models also allowed us to identify possible areas showing high Wallacean shortfall for these species. Thus, the results reinforce the importance of field work, access to physical and digital botanical collections and the integrated use of tools for a more reliable survey of biodiversity.

High richness, new occurrences, and threatened species in a savanna grassland remnant in the largest Brazilian metropolis

Parque Estadual do Juquery is the largest protected remnant of savanna grassland in the metropolitan region of São Paulo (MRSP). We conducted a floristic inventory and created a photographic record of the angiosperm flora of the savanna formations in this area and compared it with those of other Cerrado sites using Jaccard’s similarity index. We present a list with 366 species, distributed in 58 botanical families. Asteraceae and Poaceae were the families with the highest species richness. Eighty-six new occurrences were recorded in the park. According to the São Paulo state Red List, 14 species are threatened by extinction, of which four are presumably extinct. Most species are herbaceous (36.0%) and sub-shrub plants (26.5%). No floristic similarity was observed with other savanna formations in the countryside of the state of São Paulo. Our results emphasize the importance of the Parque Estadual do Juquery for the conservation of savanna grassland formations in the MRSP and the protection of locally endangered species.