142 resultados para vegetation attributes


Relevância:

20.00% 20.00%

Publicador:

Resumo:

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Relevância:

20.00% 20.00%

Publicador:

Resumo:

13C e 14C obtidos da matéria orgânica do solo foram usados para diferenciar fases de flutuação da vegetação em transição floresta-savana. A região apresenta baixos platôs com depressões topográficas imperfeitamente drenadas na superfície. Na topossequência estudada foram analisados solos de cinco perfis localizados sob floresta (F), transição floresta-savana (S1), borda da depressão sob savana (S2) e centro da depressão sob savana (S3). Os valores de 13C e idades evidenciam que a ~ 200cm de profundidade, com idades entre ~ 12.000 e 10.000 A.P., valores de -27‰ a -27,7‰ indicam vegetação de floresta (C3) em todos os perfis. Na profundidade de 100 cm, com idades entre ~ 6.000 e 5.000 A.P., houve enriquecimento de – 20,2‰ a -22,3‰, indicando regressão da floresta e expansão da savana. Valores entre -15,9 e -18,7‰ a 50-60 cm, estimado entre ~ 4.700 a 3.800 A.P., sugere máxima expansão da vegetação C4 em resposta às condições climáticas mais secas, exceto no perfil S3 com valores mais empobrecidos (-20,9‰), sugerindo que na depressão, o desenvolvimento da hidromorfia possibilitou a presença de espécies de gramíneas C3 e C4 da savana em resposta as mudanças das condições ambientais.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

A utilização de ecossistemas naturais como meta a ser atingida e a seleção de indicadores para monitoramento dos projetos são temas controversos na ciência e na prática da restauração. Analisamos a vegetação ripária em quatro remanescentes de Floresta Estacional Semidecidual, para verificar se alguns atributos dessas comunidades se repetem em diferentes locais, podendo ser referência para esta região fitogeográfica. Instalamos dez parcelas de 100 m² em cada local, amostramos plantas lenhosas com altura ≥ 0,5 m, divididas em estrato regenerante (DAP < 5 cm) e estrato arbóreo (DAP ≥ 5 cm) e classificamos as espécies com base em atributos funcionais, raridade e status de ameaça. Contabilizamos lianas, pteridófitas e árvores com epífitas. As variáveis estruturais de densidade (estrato arbóreo e regenerante e árvores com epífitas), área basal e cobertura de copas não diferiram entre locais. Foram pouco variáveis entre as áreas a riqueza rarefeita para 100 indivíduos no estrato arbóreo, a riqueza total estimada por Jackknife e as proporções de espécies raras, tolerantes à sombra, de crescimento lento e zoocóricas. Porém, analisando-se a proporção de indivíduos na comunidade, somente a tolerância à sombra foi pouco variável. Para as outras variáveis analisadas não existem padrões que possam ser considerados referência para esta região fitogeográfica. No entanto, ainda que para algumas variáveis existam padrões, sua utilização como meta da restauração depende de: 1) prazos longos para monitoramento de projetos e, sobretudo, 2) estudos que demonstrem que os ecossistemas restaurados podem, um dia, igualar aos ecossistemas pré-existentes.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The socioeconomic importance of sugar cane in Brazil is unquestionable because it is the raw material for the production of ethanol and sugar. The accurate spatial intervention in the management of the crop, resulting zones of soil management, increases productivity as well as its agricultural yields. The spatial and Person's correlations between sugarcane attributes and physico-chemical attributes of a Typic Tropustalf were studied in the growing season of 2009, in Suzanápolis, State of São Paulo, Brazil (20°28'10'' S lat.; 50°49'20'' W long.), in order to obtain the one that best correlates with agricultural productivity. Thus, the geostatistical grid with 120 sampling points was installed to soil and data collection in a plot of 14.6 ha with second crop sugarcane. Due to their substantial and excellent linear and spatial correlations with the productivity of the sugarcane, the population of plants and the organic matter content of the soil, by evidencing substantial correlations, linear and spatial, with the productivity of sugarcane, were indicators of management zones strongly attached to such productivity.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This study aimed to investigate the potential use of magnetic susceptibility (MS) as pedotransfer function to predict soil attributes under two sugarcane harvesting management systems. For each area of 1 ha (one with green sugarcane mechanized harvesting and other one with burnt sugarcane manual harvesting), 126 soil samples were collected and subjected to laboratory analysis to determine soil physical, chemical and mineralogical attributes and for measuring of MS. Data were submitted to descriptive statistics by calculating the mean and coefficient of variation. In order to compare the means in the different harvesting management systems it was carried out the Tukey test at a significance level of 5%. In order to investigate the correlation of the MS with other soil properties it was made the correlation test and aiming to assess how the MS contributes to the prediction of soil complex attributes it was made the multiple linear regressions. The results demonstrate that MS showed, in both sugarcane harvesting management systems, statistical correlation with chemical, physical and mineralogical soil attributes and it also showed potential to be used as pedotransfer function to predict attributes of the studied oxisol.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Pós-graduação em Agronomia (Irrigação e Drenagem) - FCA

Relevância:

20.00% 20.00%

Publicador:

Resumo:

In crop year 2006/07, in Selviria, MS, Brazil, were analyzed the productivity of beans because of the chemical attributes of an Acrustox cultivated under conditions of high technological level of management by no-tillage irrigated with pivot central. The objective was to select, among the attributes studied soil, the one with the best representation to explain the variability of agricultural productivity. Geostatistical grid was installed to collect data from soil and plant, with 117 sampling points in an area of 2,025 m(2) and homogeneous slope of 0.055 m m(-1). From the standpoint of linear and spatial bean yield was respectively explained in terms of P and soil pH. So much for the values of phosphorus (P) in the intermediate layer and subsurface between 24-26 mg dm(-3), as well as for Hydrogen (pH) in the surface layer between 5.0 to 5.4, resulted in sites with the most high yield (2,160-2,665 kg ha(-1)).

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Soil CO2 emission (F-CO2) is influenced by chemical, physical and biological factors that affect the production of CO2 in the soil and its transport to the atmosphere. F-CO2 varies in time and space depending on environmental conditions, including the management of the agricultural area. The aim of this study was to investigate the spatial variability structure of F-CO2 and soil attributes in a mechanically harvested sugarcane area (green harvest) using fractal dimension (D-F) derived from isotropic variograms at different scales (fractograms). F-CO2 showed an overall average of 1.51 mu mol CO2 m(-2) s(-1) and correlated significantly (P < 0.05) with soil physical attributes, such as soil bulk density, air-filled pore space, macroporosity and microporosity. Topologically significant DF values were obtained from the characterization of F-CO2 at medium and large scales (above 20 m), with values of 2.92 and 2.90, respectively. The variations in D-F with scales indicate that the spatial variability structure of F-CO2 was similar to that observed for soil temperature and total pore volume and was the inverse of that observed for other soil attributes, such as soil moisture, soil bulk density, microporosity, air-filled pore space, silt and clay content, pH, available phosphorus and the sum of bases. Thus, the spatial variability structure of F-CO2 presented a significant relationship with the spatial variability structure for most soil attributes, indicating the possibility of using fractograms as a tool to better describe the spatial dependence of variables along the scale. (C) 2014 Elsevier B.V. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Knowing the attributes of the most suitable species to overcome the obstacles in different environmental conditions is an important tool for ecological restoration. To evaluate the comparative performance of native Cerrado species being cultivated at an arboretum (Assis State Forest, Assis, SP, Brazil), we categorized 106 species by the following attributes: average annual increment in height and crown diameter, survival rates, frequency of herbivory, frost susceptibility and seed dispersal syndrome. The score of each attribute may vary from 1 to 3, and the value of a species for restoration was generated from the sum of the scores for the different attributes converted to the scale of 0 to 100. Analyzing the species altogether, survival was 70%, the average annual increment was 30 cm in height and 21 cm in crown diameter. Only 8% of the species showed high susceptibility to frost and 17% high frequency of herbivory. Eighteen species had scores above 80, being the first Annona crassiflora, Cecropia pachystachya, Enterolobium gummiferum, Plathymenia reticulata e Protium heptaphyllum. In this group are the species that gather the highest number of favorable attributes for the restoration of Cerrado vegetation. We generated two separate lists of ten species of higher value, one for the cerrado sensu stricto and the other for cerradao the forest type of cerrado vegetation. We believe that using these species accelerates the recovery of vegetation structure and thus provide the restoration of ecological processes of ecosystems undergoing restoration. At the end of the list are species of low scores, which, if used, can lead to higher costs or delay in the recovery of structure and ecological processes of the ecosystem being restored.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)