Soil and phytosociological characterization of an area with predominance of arnica (Lychnophora pohlii sch. bip.)

Lychnophora pohlii Sch. Bip. (Asteraceae), known as "Arnica mineira", is widely used in folk medicine and very abundant in the altitude vegetation of rocky grassland. The aim of this work was to study the density of this species and its relationship with soil parameters in rocky grassland in Diamantina, in the Upper Jequitinhonha region, Minas Gerais. Ten contiguous 20 x 50 m plots were marked (total sampled area 10,000 m²) on the campus Juscelino Kubitschek of the Federal University of Jequitinhonha and Mucuri Valleys (UFVJM). The plants in these plots were evaluated for frequency, dominance and density. The relationship between the density of this species with nine soil physical and chemical properties was analyzed by means of canonical correspondence analysis (CCA). The highest plant abundance (I) of the species Lychnophora pohlii Sch. Bip. was found in the vegetation sampling areas: plot 6 with 255 plants, plot 7 with 173, plot 8 with 189, plot 9 with 159, and plot 1 with 151 plants. In these areas, the floristic soil characteristics were similar, resulting in spatial proximity in the ACC diagrams. The density of Lychnophora pohlii was higher in plots with higher pH, P-rem and base saturation, the variables most strongly correlated with the first axis of canonical correspondence analysis.

Phytosociological surveys: tools for weed science?

In simple terms, a phytosociological survey is a group of ecological evaluation methods whose aim is to provide a comprehensive overview of both the composition and distribution of plant species in a given plant community. To understand the applicability of phytosociological surveys for weed science, as well as their validity, their ecological basis should be understood and the most suitable ones need to be chosen, because cultivated fields present a relatively distinct group of selecting factors when compared to natural plant communities. For weed science, the following sequence of steps is proposed as the most suitable: (1) overall infestation; (2) phytosociological tables/graphs; (3) intra-characterization by diversity; (4) inter-characterization and grouping by cluster analysis. A summary of methods is established in order to assist Weed Science researchers through their steps into the realm of phytosociology.

Phytosociological variability of weeds in soybean field

Understanding spatial distribution of weeds in the crop enables to perform localized herbicide applications, increasing the technical and economic efficiency of operations and reducing environmental impacts. This work aimed to characterize the spatial and phytosociological variability of weeds occurring in soybean commercial field. It was conducted in an agricultural area located at the municipality of Boa Vista das Missões - RS, during the 2010/2011 harvest season. The area, that had been managed under no-tillage with soybean monoculture (summer) for five years, was divided in regular squares of 50 x 50 m (0.25 ha), totalizing 356 points. For species identification, 0.5 x 0.5 m sample squares were used. During the survey, 1,739 individuals were identified, distributed in 19 species of 13 families. The weed species Cardiospermum halicacabum, Digitaria horizontalis, Urochloa plantaginea and Raphanus raphanistrum showed the highest population variation in the area; however, only C. halicacabum, U. plantaginea and R. raphanistrum stood out based on the Importance Index Value (IVI). Localized management strategies considering the spatial variability of weed species placed in the Magnoliopsidas and Liliopsidas group show a high potential for use in soybean crop. The results show that the sampling method through regular grid was capable of characterizing the occurrence, population density and spatial variability of weed species in soybean crop.

Weed Phytosociological and Floristic Survey in Agricultural Areas of Southwestern Goiás Region

The use of the Roundup Ready(r) technology and the cultivation of a second crop influence the floristic composition of weed communities in Brazilian Central-West region cropping systems. This study has aimed to diagnose the dominant weed species in southwestern Goiás in areas of genetically-modified and conventional soybeans, using phytosociological and floristic surveys. Weed sampling was obtained by collecting all the plants present within a 0.5 m hollow frame, randomly thrown 20 times in each of thirty-five agricultural areas in the 2012/2013 harvest. Field survey was carried out in three periods: before desiccation for soybean sowing, before postemergence herbicide in soybean first application and before postemergence herbicide application in late harvest. A total of 525 m2 was inventoried and 3,219 weeds were collected, which included 79 species, 58 genera and 28 families. Families Poaceae, Asteraceae, Euphorbiaceae, Fabaceae, Amaranthaceae, were the most representative in the survey. Species Cenchrus echinatus, Glycine max, Chamaesyce hirta, Commelina benghalensis, and Alternanthera tenella stood out in importance. The RR+millet soybean treatment had the highest number of species (44), while the conventional soybean + sorghum treatment had the lowest number of species (18). The highest number of species was recorded in first sampling period. Treatments conventional soybean + maize and conventional soybean + millet showed higher similarity (70%), while treatments RR soybean + millet and conventional soybean + sorghum showed the least (51%). Species of difficult control were recorded in all cultivation systems analyzed.

Phytosociological study on the tree stratum of a semideciduous mesophytic forest in the municipality of Jau, SP, Brazil

Through the point-centered quarter method, a phytosociological study was carried out in an area of semideciduous mesophytic forest with 190 ha, in the municipality of Jahu,SP. Due to the fact of the forest be crossed by three small rivers, for the sampling process, the Total Area was divided in two sampling areas: the Area I (under the influence of the rivers) and the Area II (without this influence). Some differences between the two regions were observed.

Phytosociological study of the tree stratum of a semideciduous mesophytic forest in the municipality of Botucatu, SP, Brazil

The phytosociological structure was studied in an area of semideciduous mesophytic forest lied on the ascent of the Cuesta of Botucatu. Once the relief of the area was very heterogeneous, the forest, for the sampling process, was divided in three sampling regions: the upper one (on the plateau), the middle one (on the ascent properly said) and the lower one (on the plain). Through the point-centered method, 1224 (408 in each region) trees were sampled. For this work, only the trees with shaft equal or higher than 1.30m high were considered. The three sampling regions showed some interesting differences in regard to the phytosociologic structure. Once there are differences among the soil of the three regions, the variations in the structure must be connected to the differences in the soil.

Phytosociological studies in the morro do diabo forest (Pontal do Paranapanema, SP), Brazil

Results are given of a phytosociological study of a forest located in the Morro do Diabo State Park. in the county of Teodoro Sampaio (22 degrees 31'S, 52 degrees 10'W), Pontal do Paranapanema region, state of São Paulo. The point-centered quarter method, using 300 sampling points, was used establishing 3 trails of 100 sampling points each, 10 m interdistant. All woody vegetation with a breast height diameter of 5 cm or more were samplied. Three distinct ecotopes could be identified in the forest: the lower, thc slope and the peak, which were analised separately.The families that presented the greatest numbers of genera, species and individuals were Leguminosae, Euphorbiaceae and Myrtaceae, followed by Rutaceae, Lauraceae, Meliaceae and Moracea. A total of 104 species, 85 genera and 37 families were sampled by the phytosociological survey. The relative sociological position of each plant family or species varied according to ecotope.

The flora and vegetation of rocky outcrops in three municipalities in the northern region of Ceará, Brazil: phytosociological characterization

This study aims to identify the flora and vegetation of rocky outcrops of low altitude and confined in the municipalities of Sobral, Groaíras and Santa Quitéria (Ceará state, Brazil), to propose a phytosociological classification for the xerophilous communities. We selected five stations in areas with high proportion of bare rock (> 80%), and the field work were conducted in March 2014 and 2015 respectively (3º 56’ S and 40º 23’ W, 4º 01’ S and 40º 05’ W, 4º 07’’ S and 40º 08’ W, 4º 09’ S and 40º 09’ W and 4º 03’ S and 40º 00’ W). Floristic relevés were made following the Braun-Blanquet classic sigmatist method. The minimum areas of the floristic relevés vary between 8 e 16 m². All the plant species growing in cracks, crevices and vegetation "spots" that can be found in these habitats were identified. The classification of the relevés was made through the Twinspan. The floristic list is composed of 89 species, distributed in 61 genera and 29 families. Fabaceae was the most representative in species richness, 20 species, followed by Poaceae (10 spp.), Euphorbiaceae (7 spp.) and Convolvulaceae (6 spp.). 22 Brazilian endemisms have been identified. Based in the phytosociological analysis and in the classification results we identified five groups and two communities can be clearly distinguished: community of Pilosocereus gounellei FA.C.Weber) Byles & Rowley and Encholirium spectabile Mart. ex Schult. & Schult.f. and the community of Crateva tapia L. and Combretum leprosum Mart..

Phytosociological survey on the Lusitan-Extremadurean grasslands of Dactylis hispanica subsp. lusitanica (Stebbins & D.Zohary) Rivas-Mart. & Izco

Deeply connected with forest serial dynamics, and present in almost semi-natural landscapes of Iberian Peninsula, Dactylis hispanica subsp. lusitanica perennial grasslands antalis a major issue on biogeographical analysis, once it lacks on syntaxonomical solutions for its affiliation and respective positioning on serial dynamics of distinct territories, which edaphoclimatic envelopes suggest different floristic assemblages. Mainly part of Agrostion castellanae-Stipion giganteae alliance, the Lusitan-Extremadurean grasslands were studied, with the objective of updating that biogeographic Province, and several phytosociological relevés were made, allowing the syntaxonomical update as well to resolve the serial-dynamics arrangement where this peculiar grasslands makes part of. At last this communities belong to priority 6220 [*Pseudo-stepe with grasses and annuals (Thero-Brachypodietea)], habitat that interests as well for conservational matters, due to its peculiar flora.

Levantamento fitossociológico e caráter sucessional de um trecho de floresta secundária ciliar em Juquitiba, SP, Brasil

The objective of this study was to evaluate the horizontal and vertical structures of tree community in regeneration in a fragment of a secondary riparian forest at approximately 30 years of age and to identify the most abundant species in each fragment of the forest to determine the sucessional stage. An area of 800 m² was subdivided into 16 samples of 10 x 5 m and all individuals with DBH ≥ 1 cm were sampled and identified for the following analyzes: horizontal parameters (DR, FR, DoR, IVC and IVI), vertical parameters (PSR and RNR) and mixed parameters, from of value of increased importance index (IVIa). The survey measured 689 individuals, belonging to 38 families, 74 genus and 109 species. The total density was 8,614 individuals/ha. The index of Shannon´s diversity was 3.99 and the index of Pielou´s equability was 0.85. Tibouchina pulchra, Psychotria suterella and Endlicheria paniculata obtained high values of IVIa. Guarea macrophylla, Gomidesia anacardiaefolia, Xylopia langsdorffiana and Endlicheria paniculata achieved high values of RNT, indicating adequate natural regeneration in the plot. The initial secondary and umbrophylous species showed the highest ecological importance in this fragment of the forest, with the highest values of sociologic position and importance index. Furthermore, the presence of late secondary species in all layers suggest that the studied fragment is in intermediate succession degree.

O Complexo Vegetacional da Zona Litorânea no Ceará: Pecém, São Gonçalo do Amarante

Due to its geographical location, the northeastern Coast of Brazil (Litoral Setentrional do Nordeste - LSN) is a hotter and drier climate than the eastern coast. In addition, because of its proximity to caatinga and cerrado, the LSN contains species from these vegetation biomes and from the restinga on the coast, which comprise different plant formations and creates a vegetation complex. Despite the great importance of this ecotone, there are few studies about its flora. The objective of this work was to contribute to what is known about the floristic and phytosociological composition of this region. We made a floristic survey in the area (between 2007 and 2011), consulted herbaria data from the region and made a phytosociological study in a stretch of coastal semideciduous forest (mata de tabuleiro). The study recorded 382 plant species from 96 families. In the phytosociological survey (0.32 ha) we recorded 2,970 individuals and 52 species. The most abundant plants surveyed were the trees Manilkara triflora, Chamaecrista ensiformis and Guapira nitida and the shrubs Cordiera sessilis and Maytenus erythroxyla (average height 3.8 m, average diameter 6.2 cm, basal area 39.28 m²/ha). The local flora includes floristic elements of caatinga, cerrado and restinga, corroborating the idea that the plant community of the coastal region of Ceará has an ecotonal nature.