Eleandro José Brun

Retorno de nutrientes via deposição de serapilheira em um povoamento de acácia-negra (Acacia mearnsii De Wild.) no Estado do Rio Grande do Sul

This study aimed to evaluate all the aspects involved in the transfer of litterfall and nutrients into the soil in a 3-year-old Black-wattle stand (Acacia mearnsii De Wild.), in Butia, RS. For the experiment, 5 plots of 18 m x 24 m were allocated systematically. In these plots, 20 litter collectors of 1 m 2 were distributed (4 in each plot). For branch collection, 15 splitplots of 3 m x 3 m were delimited on the soil surface. The intercepted material was collected monthly from May/1999 to December/2001. After collection, the material was separated in fractions (leaves, branches, flowers, fruits and feces), oven-dried, weighed, ground and chemically analyzed for concentrations of N, P, K, Ca and Mg. The annual average deposition of litter achieved 5.85 Mg/ha, being 77.0% leaves, 3.7% branches, 2.5% flowers, 2.4% fruits and 14.3% feces. The low deposition of branches. Litterfall was more concentrated in the summer. The largest supply of nutrients to the soil occurred through the fraction leaves. The fractions with higher concentrations of N, P and Mg were the flowers and the fruits, only differing from the leaves and feces in Ca concentration and not differing in relation to K. The magnitude of nutrient transfer to the soil was 106.2 of N> 62.8 of Ca> 41.8 of K> 9.4 of Mg> 3.4 of P, in kg/ha.

Litterfall in an Araucaria angustifolia (Bertol.) Kuntze forest in Pinhal Grande, RS

The objective of this work was to evaluate the annual deposition of litter and macronutrient devolution (N, P, K, Ca and Mg) in a 17 year - old stand of Araucaria angustifolia in Pinhal Grande, RS. The experiment was arranged in a randomized design (5 plots of 10 m x 20 m). In each plot 4 wooder collectors of 1 m2 of area were systematically distributed. The material was collected monthly during one year and separated in needle and branch fractions, stove-dried and weighed in a precision balance, milled and analyzed chemically. Litter deposition was 6.96 Mg/ha, composed by 74% needles and 26% branches. An outstanding deposition seasonality with deposition peacs between spring and summer was observed, decreasing towards the autumn and winter months, according to the average monthly precipitation. Needles and branches were responsible for the return to the forest floor of 84% and 16% of the total of the nutrients, which was 254,3 kg/ha. Calcium presented the highest devolution (177.1 kg/ha). The expressive amount of nutrients returned to the soil demonstrates the importance of litter in maintaining productive local capacity.

Avaliação da sazonalidade da produção de serapilheira numa Floresta Estacional Decidual no município de Santa Maria-RS

The amount of litter produced and its seasonal fall were estimated during the period of one year, in a Seasonal Deciduous Forest ecosystem next to Santa Maria, RS. Thirty round-shaped metal collectors (50 cm diameter) were used, systematically distributed in 6 rectangular plots (10 m x 20 m) presenting similar environmental characteristics. The material deposited was collected monthly, separated into different fractions, dried and weighed. Litter production was 9.2 Mg/ha/year, presenting the following composition: 67.8% of leaves, 19.3% of fine branches and 12.9% of miscellany (flowers, fruit, seeds and other plant materials). The greatest amounts of litter production occurred between the months of July and September, in the winter, and the smallest productions between October and April, in the spring and summer. The devolution of litter presented negative correlations with the temperature.

Estudo fenológico em três fases sucessionais de uma floresta estacional decidual no município de Santa Tereza, RS, Brasil

n The present study was accomplished in forty permanent plots belonging to three forest successional stages, denominated: Brush Forest, Secondary Forest and Mature Forest, in a seasonal deciduous forest in the municipal district of Santa Tereza, RS, Brazil. Phenologic observations were accomplished fortnightly for 53 arboreal species, in an average of 8,4 individuals per species, during the period of November 2001 to November 2002. The stages observed were flowering, fruiting and foliage change. The results indicate that the reproductive activity remained relatively low for three successional stages during the observed period, with a tendency to be even lower during winter. The total amount of leaves on the trees, regardless of the successional stage, decreased from approximately 85%, in the period of higher vegetative activity, to 35% in the winter, resting season. The Mature Forest maintained the largest percentage of leaves during the studied period.

Banco de sementes do solo em três fases sucessionais de uma Floresta Estacional Decidual em Santa Tereza, RS.

With the objective of evaluating soil seed bank and understanding aspects of the sucessional dynamics of a Seasonal Deciduous Forest, 60 samples of 1 m 2 were collected at the end of each season, in three sucessional phases (understory, secondary forest and mature forest). In each sample point it was collected the litter and the first 3 cm of soil. In laboratory at UFSM the material was placed to germinate, separately, in stonemasons of wood of 1 m 2 , that contained 5 cm of horizon B soil as substratum. The stonemasons were covered with sombrite of 50% for understory, 70% for the secondary forest and 80% for the mature forest. There were made qualitative and quantitative evaluations, by species and sample unit, 20 days after placing in nursery and afterward every 30 days. The frequency and relative density, the Index of Value of Importance for the seed bank and the Index of Diversity of Shannon were calculated. There were 216 individuals, most of them in the mature forest, which also presented the largest floristic richness. In the three subsere s, there was predominance of secondary initial species. The spring season presented the largest abundance of species; however, in summer happened the largest density of individuals per area.

A quitosana como fungistático no crescimento micelial de Rhizoctonia solani Kuhn

Rhizoctonia solani is a fungus that causes damping-off of seedlings in various plant species. Chitosan is a polymer derived from the process of desacetylation of chitin, which is found in large quantities in the exoskeleton of crustaceans, insects and fungal cell wall. Chitosan has been tested for various uses, including the control of plant pathogens in agriculture, since it presents antimicrobial activity to control pathogens. This study aimed to evaluate the fungistatic effect of different chitosan concentrations (0; 0.25; 0.5; 1 and 2%) in mycelial growth in vitro of the fungus R. solani. The results showed a significant effect of different concentrations of chitosan, in reduccing the mycelial growth of R. solani. It was also observed increased fungistatic effect with increasing of the concentration.

Compactação do solo causada por tratores florestais na colheita de Pinus taeda L. na região sudoeste do Paraná

Soil compaction has been becoming one of the main impacts caused by mechanized harvesting activities. The weight and movement of machines at the time of cutting and loading timber combined with the inappropriate moisture condition of the soil are the main causes of soil structural degradation, observed mainly by changes in physical properties. Thus, this work aimed to identify soil compaction caused due to forest harvesting of Pinus taeda L. performed on three different soil moistures. The study was conducted in the operational areas of a forestry company located in Parana on red latosol. The treatments consisted of the interaction of three factors: moisture (rainy day harvesting and 3 and 7 days after rain), harvesting operations (machine traffic, no machine traffic/eventual timer landing and yard), and time of collection (before and after harvest). The residual biomass from forest harvesting was essential to minimize soil compaction caused by machinery traffic that was close to the maximum. The gradation of soil moisture represented by the different days of harvest after a rain did not influence differently the soil compaction. However, harvesting operations impacted soil to a depth of 10 cm causing compaction on the traffic lines of the machines, while the others operations did not cause changes in density, macroporosity and resistance to penetration.

Espectrorradiometria na região do visível e do infravermelho próximo em povoamento de Eucalyptus grandis Hill ex Maiden

Leituras de reflectância em folhas de arvores de bordadura e de interior de um povoamento florestal de Eucalyptus grandis , no municipio de Sao Pedro das Missoes - RS, foram analisadas nas regioes do espectro eletromagnetico visivel e do infravermelho proximo, utilizando-se espectrorradiometria. A area foi dividida em duas partes: bordadura e centro do povoamento. Para a coleta de material, a copa das arvores foi dividida em tres partes (superior, media e inferior), de forma a diferenciar as posicoes de coleta de folhas, em cada uma das areas. Foram amostradas tres arvores em cada area, totalizando seis arvores, sendo que para cada arvore foram coletadas 60 folhas isoladas, 20 em cada posicao. As leituras de reflectância foram realizadas atraves do espectrorradiometro FieldSpec®3 e os resultados finais foram segmentados nas bandas espectrais do visivel e do infravermelho proximo. A analise estatistica valeu-se do teste Tukey HSD, para comparacao das medias da regiao do visivel, que de acordo com a ANOVA apresentaram diferencas significativas. Conclui-se que as classes indicadas de coleta de folhas para analise espectrorradiometrica na regiao do visivel sao preferencialmente a 5 (arvore de centro, leitura na parte mediana) e a 3 (arvore de bordadura, leitura parte superior).

Development and nutrition of black wattle seedlings (Acacia mearnsii de Wild. De Wild.) in poultry litter substrate

We evaluated the development and the nutritional status of Acacia mearnsii De Wild. seedlings produced in four organic substrates with poultry litter base, distributed in percentage terms: T1: 25CA:50S:25A; T2: 50CA25S25A; T3: 25CA75S and T4: 100SC (CA: poultry litter; S: soil; A: sand; SC: commercial substrate), in tubes of 125 cm 3 conducted in greenhouse / shade area. The best results, to the morphological variables height, stem diameter, number of leaves, dry mass of roots and total, were obtained in commercial substrate and in between 25 to 50% of poultry litter with clay soil and sand. The N and Mg contents (shoot and roots) and P and K (shoot) were not influenced by substrates. In the roots, the P content was greater on treatment with biggest proportion of clay soil. The K, in the roots, had the highest levels in substrates composed of 25 to 50% of poultry litter and commercial substrate. For Ca, the contents in shoots were higher than roots, mainly in the substrates with up to 50% of poultry litter. In the roots, the proportion of poultry litter did not influence Ca. The tested substrates, generally, did not influence the nutritional status of the seedlings.

Danos causados por gado leiteiro no componente arbóreo de sistema silvipastoril

The study aimed to quantify the damage caused by dairy cattle on the growth and recovery capacity of hybrid Eucalyptus grandis x E. camaldulensis (grancam) trees in a experimental silvopastoral system implanted in October/2012, after release of animals in the area in winter/2014. The experimental design consisted of a two-factor scheme, considering the distance between the animals entering the area and the double planting lines (factor 1) and the two evaluation occasions (February / 2015 and July / 2016) (factor 2). The damage levels (low / medium / high) were classified and their interference on growth in diameter at breast height (DBH) and total height (Ht), as well as the recovery capacity of the trees were evaluated. There was no significant interaction between factor 1 and 2 for DBH. The trees of the lines closest to the place of entry of the animals in the area showed a lower DBH (19.7 and 20.6 cm) in relation to the furthest lines (26.1 and 23.9 cm). The interaction was significant for Ht, but not significant difference between the lines. At the two evaluations, there was a general average increase of 2.59 cm year -1 in DBH and, in Ht, of 5.9 and 6.0 m in year -1 in lines 2 and 4, 4.6 and 4.4 m year -1 in lines 1 and 3, respectively. In 2015, most of the trees presented high-level of damage (65%), falling to 6.7% in 2016, showing the recuperation capacity of grancam. There was a significant inverse correlation between DBH and Ht with high level of damage (r = -0.25 and -0.24, respectively), showing that small trees are more susceptible to damage by cattle.