Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Biomassa de raízes em sistemas florestais dispersos nas matrizes de savana da Amazônia é pobremente estudada e indiretamente calculada dentro do Inventário Nacional sobre fontes e reservatórios de carbono do Brasil. O objetivo do estudo foi estimar a biomassa de raízes em ilhas de mata dispersas na savana de Roraima levando em consideração o efeito da dimensão destes fragmentos florestais, distribuição espacial (borda e interior) e das variáveis edáficas como fontes de variação da biomassa. A amostragem foi desenvolvida em 12 ilhas de mata distintas por categorias de dimensão (pequenas ≤ 10 ha, médias = 1020 ha, grandes = 20-60 ha) e pela borda e interior do fragmento. Tradagens de solo (1 m de profundidade) foram realizadas de forma equidistante ao longo de transectos estabelecidos no sentido norte sul em cada ilha. Todas as raízes com diâmetro ≥ 2 mm foram triadas manualmente a intervalos de 10 cm no perfil vertical do solo e transformadas em massa por unidade de área. Foram realizadas análises químicas e físicas do solo a cada intervalo de 10 cm. A análise dos dados foi realizada através de ANOVA, teste t e regressão linear. A biomassa de raízes não diferiu em relação a dimensão dos fragmentos (38,8 22,4 Mg ha-1 de média geral). No entanto, a média das bordas (37,6 19,6 Mg ha-1) foi distinta do interior (23,3 24,4 Mg ha-1), independente da dimensão das ilhas, sugerindo ser afetada por diferenças florísticas e estruturais entre a borda e o interior. Apenas 50% da variação da biomassa de raízes ao longo do perfil vertical (0-1 m) foram explicados pelas variáveis edáficas devido à uniformidade química e física dos solos amostrados. A maior concentração de raízes foi registrada entre 0-30 cm (finas = 32,8%, médias = 55,9% e grossas = 11,3%), não sendo observadas diferenças entre as dimensões dos fragmentos neste intervalo de profundidade. O valor médio da razão root:shoot nas ilhas amostradas foi de 0,40 0,28 no perfil de 0 a 1 m de profundidade A conclusão do estudo é que biomassa de raízes em fragmentos florestais dispersos na savana de Roraima não é afetada pela dimensão dos fragmentos, mas é distinta entre borda e interior das ilhas, podendo ser explicada pelas diferenças na estrutura e composição florística entre borda e interior. / Root biomass in forest ecosystems scattered in Amazonian savanna matrix is poorly studied and indirectly calculated within the National Inventory of carbon sources and reservoirs in Brazil. The goal of the study is to estimate root biomass in forest islands dispersed in Roraima savanna taking into account the size effect of these forest fragments, spatial distribution (edge and interior) and edaphic variables as biomass sources of variation. Sampling was conducted in 12 different forest islands by size categories (small ≤10 ha, medium = 10-20 ha, large = 20-60 ha) and the edge and the forest interior. Soil samples (1 m deep) were performed at equal distances along transects established in the north - south direction on each forest island. All root diameter ≥ 2 mm were manually screened at intervals of 10 cm in the soil vertical column and converted in mass per unit area. Chemical and physical soil analyzes were made in each10 cm interval. Data analysis was performed using ANOVA, t test and linear regression. The average root biomass did not differ in the size of fragments, resulting in 38.8 22.4 t ha-1 as the overall mean for all fragments. However the edge mean (37.6 19.6 t ha-1) was distinct from the interior (23.3 24.4 t ha-1), regardless of the size of the islands, suggesting that it is affected by floristic and structural distinctions between the edge and the interior. Only 50% of the variation in root biomass along the vertical profile (0-1 m) were explained by the soil characteristics due to chemical and physical uniformity of the sampled soils. The highest concentration of roots was recorded between 0-30 cm (fine = 32.8%, medium = 55.9% and coarse = 11.3%), with no differences between the sizes of the fragments in this depth range. The ratio root: shoot in the sampled forest islands was 0.40 0.28 (0-1 m deep). The conclusion is that root biomass in forest fragments dispersed in Roraima savannah is not affected by the size of the fragments, but is distinct between edge and interior of the islands, which can be partially explained by differences in the structure and floristic composition between edge and interior.

Andean montane forests are one of the most diverse ecosystems on Earth, but are also highly vulnerable to climate change. Therefore, the link between plant distribution and ecosystem productivity is a critical point to investigate in these ecosystems. Are the patterns in productivity observed in montane forest due to species turnover along the elevational gradients? Methodological constraints keep this question unanswered. Also, despite their importance, belowground biomass remains poorly quantified and understood. I measured two plant functional traits in seedlings, root:shoot ratio and specific leaf area, to identify different strategies in growth and biomass allocation across elevations. A tradeoff in specific leaf area with elevation was found in only one species, and no generalized directional change was detected with elevations for root:shoot ratio. Lack of information for the ontogeny of the measured plant traits could confounding the analysis.

Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2017-09-15T18:57:49Z No. of bitstreams: 1 2014 - Ana Carolina Carvalho de Barros.pdf: 2646968 bytes, checksum: 755045d3111f54dc02cc0c3c6834d0c5 (MD5) / Made available in DSpace on 2017-09-15T18:57:49Z (GMT). No. of bitstreams: 1 2014 - Ana Carolina Carvalho de Barros.pdf: 2646968 bytes, checksum: 755045d3111f54dc02cc0c3c6834d0c5 (MD5) Previous issue date: 2014-09-22 / CAPES / This study was carried out for evaluating the dynamics of the root dry matter stock in Florico grass pastures managed at two light interception levels (90 and 95%) and two post-grazing residue heights (0.2 and 0.3 m) (90IL 0,2m RPP; 90IL 0,3m RPP; 95IL 0,2m RPP; 95IL 0,3m RPP). The lowering of vegetation was performed by the technique "mob grazing", simulating the condition of intermittent grazing. In shoot mass were related (MFF and MF) and the rate of herbage accumulation (TAMFF and TAF) with varying root system, using the technique of digging trenches 0,5x0,4x0,6 me withdraw prism?sticos blocks per monoliths 0,05x0,2x0,1 m up to 0.4 m profundida for root stock and fractional distribution (DF), and the root / shoot ratio, and total biomass (FT). The experiment was performed at PESAGRO-RIO, in Serop?dica municipality, Rio de Janeiro state , from July, 2012 to July, 2013, covering the four seasons. Shoots fresh matter yield was effective for treatment, season, and repeated measures interaction, with total production in the summer of 2013 for the four grazing intensities (908.1 ? 73.8 g/m2), compared to other seasons where treatments were similar. In the season of different days between cycles, shoots fresh matter yield was estimated where the winter, presented the lowest yield (10.8 ? 5.1 g/m2 day 1), when compared to the rainy season (28,7 ? 13.1 g/m2 day 1), as well as, between the treatments, the highest grazing intensity presented the greatest yield (26.6 ? 15.8 g/m2 day 1) while the lowest one presented the smallest yields (13.6 ? 4.1 g/m2 day 1). Shoots dry matter yield indicated high significant effects for treatments, season, and interaction for repeated measurements over time between treatments the 90IL 0,3RPP treatment presented no difference in relation to shoot dry matter among seasons, whereas 95IL 0,3RPP treatment presented greater shoot dry matter quantity in the spring (219.8 g/m2 cycle 1), followed by summer (192.2 g/m2 cycle 1), as well as, in the autumn 90IL 0,3RPP treatment was more productive than 95IL 0,3RPP one. Shoot dry matter yield was lower in all the treatments in the winter when compared to the other seasons, the greatest roots dry matter (RDM) were: 639.3 ? 246.8 and 667.2 ? 225.7 g 400dm3 soil in the spring, for 90IL 0,3RPP and 95IL 0.3 RPP, respectively and 591.8 ? 168.2 and 655.1 ? 252.7g 400 dm3 soil in the summer anol autumn, for 90IL 0.2RPP respectively 647.8 ? 68.4g 400 dm3 soil in the autumn for 95IL 0,2RPP treatment. In regarding to the roots distribution profile there was no difference between RDM stock treatments between grazing intensities evaluated, summer and autumn equations did not differ eithen. In fractional root distribution all the seasons presented significative results, being autumn the single one no differing between treatments on the present study. Total phytomass presented significantive effect for the treatments, where the winter was the season presenting the lowest yield in all the treatments, when compared to other stations. Root:shoot ratio was no effect for treatment and season, as well as, the autumn highlighted with the greatest RDM:SDM ratio in 95IL 0,2RPP treatment, when compared to the other seasons. It might be concluded that The Florico grass was sensitive to variations in weather conditions presenting to the accumulation of forage and root stock, showing the existence of phenotypic plasticity for the evaluated variables. / Objetivou-se avaliar o estoque de massa seca de raiz em pastos de capim Florico manejados sob dois n?veis de intercepta??o luminosa (90 e 95 %) e duas alturas de res?duo p?s-pastejo (0,2 e 0,3 m), os quais deram origem a quatro tratamentos de intensidades de pastejo (90IL 0,2m RPP; 90IL 0,3m RPP; 95IL 0,2m RPP; 95IL 0,3m RPP). O rebaixamento da vegeta??o foi realizado pela t?cnica ?mob grazing?, simulando a condi??o de pastejo intermitente. Na parte a?rea foram relacionados massa (MFF e MF) e a taxa de ac?mulo de forragem (TAMFF e TAF) com vari?veis do sistema radicular, utilizando a t?cnica de escava??o de trincheiras de 0,5x0,4x0,6 m e retirada de blocos prism?sticos por mon?litos de 0,05x0,2x0,1 m, at? a profundida de 0,4 m para o estoque radicular e distribui??o fracional (DF), al?m da rela??o raiz/parte a?rea e fitomassa total (FT). O experimento foi conduzido na PESAGRO-RIO, em Serop?dica, Rio de Janeiro, de julho de 2012 a julho de 2013, durante quatro esta??es do ano. A massa fresca de forragem variou com tratamento, esta??o do ano e com a intera??o entre eles (p<0,01), apresentando maiores valores no ver?o com 908,1 ? 73,8 g m-2 (m?dias dos quatro tratamentos de pastejo), comparado com as demais esta??es que foram semelhantes entre si. Devido a varia??o existente entre os ciclos de pastejos, em dias, foi calculado a taxa de ac?mulo de forragem de massa seca de forragem, com menor valor obtido no inverno (10,8 ? 5,1 g m-2 dia-1), quando comparado ao per?odo chuvoso (28,7 ? 13,1 g m-2 dia-1). Maior taxa de ac?mulo de forragem massa fresca de forragem foi obtida para o tratamento (90IL 0,2m RPP) de maior intensidade de pastejo (26,6 ? 15,8 g m-2 dia-1) e, menor valor, para aquele (95IL 0,3m RPP) de menor intensidade (13,6 ? 4,1 g m-2 dia-1). A massa seca de forragem n?o variou (p>0,05) entre as esta??es para o tratamento 90IL 0,3m RPP, enquanto que, o tratamento 95IL 0,3RPP, na primavera e ver?o, apresentou maior massa, (219,8 e 192,2 g m-2 ciclo-1), enquanto o tratamento 90IL 0,3RPP foi mais produtivo que o 95IL 0,3RPP no outono. A produ??o de massa seca radicular (MSR) do inverno foi inferior aquelas das demais esta??es. Na primavera, os maiores estoques de MSR foi de: 639,3 ? 246,8 e 667,2 ? 225,7 g 400dm3 de solo, respectivamente , para 90IL 0,3m RPP e 95IL 0,3m RPP; enquanto que o tratamento 90IL 0,2m RPP apresentou maiores estoques de MSR: 591,8 ? 168,2 e 655,1 ? 252,7 g 400dm3 de solo-1, respectivamente no ver?o e outono e o tratamento 95IL 0,2m RPP estocou maiores quantidades de MSR no outono (647,8 ? 68,4 g 400dm3 de solo-1). Quanto a distribui??o das ra?zes no perfil, houve diferen?a do estoque de MSR entre tratamentos na primavera e, as equa??es do ver?o e outono n?o diferiram entre si. A distribui??o fracional do sistema radicular variou (p<0,05) entre todas as esta??es, por?m no outono, houve semelhan?a entre os tratamentos. A produ??o de fitomassa total variou (p<0,05) entre os tratamentos, com a menor produ??o no inverno, para os tratamentos. A rela??o raiz: parte a?rea variou (p<0,05) com tratamento e esta??o. Para 95IL 0,2m RPP, maior valor foi obtido no outono. O capim Florico foi sens?vel ?s condi??es clim?ticas apresentando varia??es quanto ao ac?mulo de forragem e estoque radicular, evidenciando a exist?ncia de plasticidade fenot?pica para as vari?veis avaliadas.

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