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Surface mining in the central Appalachian coalfield disturbs landscapes. Post-mining reforestation efforts now achieve successful reestablishment and growth; however, it is unclear whether reforestation efforts also restore the native forest ecosystem functions. We quantified rates of return of key ecosystem functions and structural attributes of the post-mining forested ecosystem. A chronosequence of four reforested mine sites and an unmined reference stand were studied in southwestern Virginia. Total soil nitrogen (N) and component (mineral soil, forest floor, root, and aboveground biomass) ecosystem carbon (C) pools were quantified. Throughout the growing season, soil gas fluxes [i.e., carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4)], soil inorganic-N [nitrate (NO3-) and ammonium (NH4+)], and total and active microbial biomass were measured. Soil organic C (SOC) and total ecosystem C are returning to the mined landscape. Ecosystem C was correlated with N (r= 0.80; p= 0.0003) and with total and active microbial biomass (r= 0.92; p=<.0001 and r= 0.86; p=<.0001). Available soil inorganic-N and CO2 and N2O fluxes showed no significant differences among study sites; however, the reforested mine soils showed a diminished capacity for CH4 uptake. Although some ecosystem components and functions rapidly returned to the mined landscape, others did not. Our results indicate that reforestation on surface mined lands is largely successful at restoring many ecosystem functions, yet certain functions are decoupled from the redeveloping ecosystem structure. Improved understanding of relationships between ecosystem functions and structural measures in this context can aid development of ecosystem restoration science and mine reclamation practice. / Master of Science

Insect herbivory on forest canopies strongly affects ecosystem nutrient cycling and availability in a variety of ways, e.g. by changing the quantity, quality and timing of nutrient input to forest soils. A qualitative method for measurements of ingestion, egestion and exuviation rates of the insect Chrysomela tremulae on leaves of the hybrid Populus tremula x tremuloides were tested in this study with the aim to detect differences in relative nutrient cycling efficiencies. The assimilation efficiency (AD), efficiency of conversion of digested food (ECD) and efficiency of conversion of ingested food (ECI) increased from 1st, through 2nd and 3rd instar larvae with generally higher efficiencies for nitrogen than carbon. Effects on nutrient limitations for the insect were also tested by increasing the C:N ratio of insect diet. A carbohydrate solution was painted onto leaves which resulted in a significant increase in C:N (p&lt;0.0001). This lead to a trend of lengthened developmental time for each ontogenetic stage, as well as higher ingestion rate and lower egestion- and exuviation rates. However, a different method of increasing the C:N ratio is recommended in future experiments since the leaves never truly absorbed the solution.

The expansion and proliferation of reactive nitrogen (N) sources, predominantly fertilizer application and fossil fuel combustion, has enriched the earth with N and acidified ecosystems. Acid rain is a primary vector of both N fertilization and acidification, initiating a cascade of consequences that alter biogeochemical cycling and global biological structure and function. Studies on N and acid influences are however rarely linked despite their common source. We used a wide, chronic gradient of N deposition (5.5 – 31 kg N ha⁻¹ yr-1) to explore patterns in carbon (C) and N cycling in light of recognized biogeochemical responses to acidic deposition. Specifically, we examined the response of key controls on dissolved C and N stability because soluble pools are involved in decomposition and nutrient recycling, the formation of soil organic matter (SOM), and the translation of elements through the biogeochemical continuum from atmospheric to soil to water. Results suggest that N deposition led to reduced organic matter C/N, enhanced net nitrification, and greater DON generation; and, these patterns were associated with changes in C composition. Conversely, physiochemical processes in the mineral soil seemed to control organic matter dynamics, with effects on N processing. Moreover, pH dependent controls on DOC stability were evidenced by changes in DOC concentration, chemical complexity and recalcitrance. These horizon-specific, differential responses to acid rain indicate that changes in the forest floor N economy were responsible for increased surface water NO3-N concentrations, whereas enhanced organomineral stability of DOC caused a significant increase in DOM concentrations in export. / Master of Science

This research investigated the long-term effects of transitioning from intensive tillage to no-till (NT) practices with cover crop (CC) incorporation on soil quality, agronomic performance, and economic returns in Virginia's Coastal Plain. Nine years after integrating NT practices and CCs, improvements in soil physical and chemical properties were observed, including a 22% to 65% increase in soil organic matter (SOM) in the top 5 cm, a 4% reduction in bulk density, and enhanced soil moisture retention in corn production. Timing of CC termination played a crucial role in optimizing biomass production and nutrient accumulation. Overall accumulation rates were 44.4 kg dry biomass ha-1 d-1, 1.22 kg N ha-1 d-1, 0.16 kg P ha-1 d-1, 1.36 kg K ha-1 d-1, and 0.08 kg S ha-1 d-1 of delayed termination between March 15 and April 30. Each additional day of cover crop growth contributed to a fertilizer value of $3.91 ha-1, highlighting the economic advantage of extending CC growth during this critical period. In 2023, CC effects on corn N fertilizer demand and yields were assessed by applying variable N rates of 0, 56, 112, and 168 kg N ha-1 at sidedressing. Greatest corn yields at each N rate were observed following hairy vetch and a vetch-dominant CC mix, which had low C:N ratios (≤12:1) and accumulated 134 to 186 kg N ha-1 in their aboveground biomass. Corn yields after these CCs were 8.5 to 9.3 Mg ha-1 at the zero N sidedressing rate, increasing to 10.8 to 11.3 Mg ha-1 at the 168 kg N ha-1 rate. However, increasing the N rate yielded minimal economic benefits for these treatments. Vetch treatments produced the highest net returns, with greater returns at lower N rates, as vetch generated an additional US$1,012 ha-1 at the zero N sidedressing rate compared to the no CC control. Conversely, cereal rye produced a negative net return across all N rates, with positive returns achievable only with state cost-share payments. The findings underscore the importance of adaptive N management strategies and policy adjustments to support environmentally and economically sustainable cover crop practices in corn production. / Doctor of Philosophy / This research examines long-term benefits of switching from intensive tillage to no-till (NT) farming with cover crops (CC) on soil health, crop performance, and economic returns in Virginia's Coastal Plain. After nine years of using NT and CCs, we saw significant improvements in soil quality: soil organic matter in the top 5 cm increased by 22% to 65%, bulk density decreased by 4%, and soil moisture retention improved in corn crops. The timing of cover crop termination was crucial for maximizing biomass and nutrient benefits. Delaying termination from March 15 to April 30 resulted in additional dry biomass and nutrients, translating into a fertilizer value of $3.91 per hectare for every day of extra growth. In 2023, we assessed how different nitrogen (N) rates affected corn yields and fertilizer needs. Best yields were achieved with hairy vetch and vetch-dominant cover crops, which had low carbon-to-nitrogen (C:N) ratios and accumulated significant N in their biomass. Although these cover crops improved yields, increasing N rates returned minimal economic gains. Vetch treatments provided the highest net returns, especially at lower N rates, generating an additional $1,012 per hectare compared to no cover crop. In contrast, cereal rye resulted in negative returns across all N rates, unless state cost-share payments were applied. These results highlight the need for flexible N management strategies and policy changes to support effective and profitable cover crop practices in corn farming.

Les écosystèmes procurent de nombreux services essentiels aux sociétés humaines à travers les effets positifs de la biodiversité des communautés d'espèces. Par conséquent, identifier le rôle des organismes vivants et les facteurs influençant la diversité de leurs fonctions (ou diversité fonctionnelle), est indispensable pour prédire efficacement l'évolution des écosystèmes soumis aux pressions locales et globales.Cette thèse s'articule donc autour de deux axes: (i) établir un cadre méthodologique pour décrire la structure fonctionnelle locale et régionale des communautés, et (ii) améliorer la connaissance de l'impact des poissons sur la dégradation de la matière organique.Dans un premier temps, nous avons consolidé les outils méthodologiques permettant (i) d'améliorer la fiabilité des dendrogrammes fonctionnels, (ii) l'étude comparative des principaux indices de diversité fonctionnelle à l'échelle locale, et (iii) le développement d'une nouvelle décomposition de la diversité fonctionnelle en composantes locale (α), régionale (γ) et turnover (β). Appliqué aux communautés ichthyologiques échantillonnés le long d'un gradient de salinité, dans le système lagunaire de Patos-Mirim (Brésil), ce socle méthodologique nous a permis de révéler une structure fonctionnelle stable le long du gradient, en dépit d'une forte variabilité en composition d'espèces, ces communautés étant structurées majoritairement par un filtre environnemental agissant sur les capacités de locomotion des poissons.Dans un second temps, nous avons étudié l'impact des communautés ichthyologiques sur le cycle des nutriments. Plus précisément, nous avons estimé le potentiel de dégradation de la matière organique de plusieurs espèces de poissons, en étudiant la diversité fonctionnelle et génétique de leur flore bactérienne intestinale. Nous avons montré que les communautés ichthyologiques pouvaient influencer le recyclage des nutriments de façon non négligeable en raison d'un important potentiel de dégradation commun à la plupart des espèces étudiées, ce potentiel étant peu affecté par la diversité génétique ou les facteurs environnementaux. / Ecosystems provide many services essential to Human societies through the positive effects of biodiversity exhibited by species communities. Therefore, identifying the role of living organisms and the factors influencing the diversity of their functions (i.e. functional diversity) is fundamental to accurately predict the evolution of ecosystems undergoing local and global pressures.This thesis is organized around two axes: (i) establishing a methodological framework to describe the functional structure of local and regional communities, and (ii) improving our knowledge of the impact of fish on the degradation of organic matter.First, we have consolidated the methodological tools through (i) the improvement of functional dendrograms reliability, (ii) the comparative study of the main indices estimating local functional diversity, and (iii) the development of a new decomposition of functional diversity into local (α) and regional (γ) components, and functional turnover (β). Applied to fish assemblages sampled along a salinity gradient in Patos-Mirim lagoons complex (Brazil), this methodological framework allowed us to reveal a steady functional structure, despite a high variability in species composition, these communities being primarily structured by environmental filtering acting on fish locomotion abilities.   In a second step, we studied the impact of fish communities on nutrient cycling. More specifically, we estimated degradation of organic matter potential of several fish species by studying the genetic and functional diversity of their intestinal bacterial flora. We showed that the fish community could significantly influence nutrient cycling through an important degradation potential, common to most species studied, which is weakly affected by genetic diversity or environmental factors.

O sistema de cultivo mínimo é caracterizado por um conjunto de operações mínimas de preparo de solo em que a maior parte dos resíduos florestais é mantida sobre o solo, a fim de garantir as demandas de produção e a sustentabilidade produtiva do sistema. Diante disto, os objetivos deste estudo foram: i) Avaliar a influência da remoção total ou parcial dos resíduos florestais e da fertilização mineral na fertilidade do solo e na produtividade de madeira; ii) Quantificar a biomassa e o estoque de nutrientes na parte aérea, em uma rotação de cultivo, sob manejo de resíduos florestais e omissões de nutrientes na fertilização mineral; iii) Quantificar a influência do manejo de resíduos florestais e da fertilização mineral na deposição, acúmulo, decomposição e qualidade nutricional da serapilheira; iv) Quantificar a exportação de nutrientes via colheita de madeira e outros componentes florestais; v) Avaliar o potencial de produtividade de madeira, com base no balanço nutricional, sob diferentes cenários de manejo florestal. Foi instalado um experimento com diferentes manejos de resíduos florestais e fertilização. Os tratamentos foram divididos em dois grupos em que o primeiro consistiu em remoção total ou parcial dos resíduos florestais: copa (folhas e galhos), casca e serapilheira. O segundo grupo de tratamentos consistiu na omissão de nutrientes na fertilização mineral: N, P, K ou calagem. Durante a rotação de oito anos foram monitoradas a fertilidade do solo, ciclagem biogeoquímica de nutrientes, crescimento e estado nutricional das árvores. Os diferentes manejos dos resíduos florestais e fertilização mineral apresentaram pouca influência na fertilidade do solo, pois, os níveis de nutrientes no solo estavam adequados, devido à aplicação de fertilizantes minerais no momento da instalação do experimento. A remoção total ou parcial dos resíduos florestais não influenciou a produtividade de madeira. Contudo, no tratamento em que o K foi omitido na fertilização, houve redução de 50% na produtividade de madeira. A omissão de P na fertilização não afetou a produtividade de madeira na rotação de cultivo avaliada, porém este foi o nutriente mais limitante quanto ao número potencial de futuras rotações. A remoção total ou parcial dos resíduos florestais não influenciou na ciclagem biogeoquímica de nutrientes, porém omissão de K via fertilização reduziu em 60% a deposição anual deste nutriente o que afetou sua a ciclagem biogeoquímica. Os resultados deste estudo mostram que embora os resíduos florestais exerçam funções fundamentais na qualidade química do solo e na nutrição mineral das árvores, a inadequada fertilização do solo pode diminuir expressivamente o potencial produtivo do sítio florestal. / The minimal tillage system is characterized by practices of reduced soil management which retains most part of forest residues in the production site, aiming to supply the forest demand and the sustainability of the production system. The aims of this study are: i) Access the effect on soil fertility and site production of total and partial removal of harvest residues and mineral fertilization. ii) Quantify the biomass and nutrient rates in trees along one eucalypt rotation, under different residues management and mineral fertilization. iii) Quantify the effects of residues management and mineral fertilization on deposition, accumulation, decomposition and nutritional qualities of litter. iv) Quantify the nutrient exportation due to the harvest, considering steam and other parts. v) Access productivity potential according to the nutritional balance under different forest management cases. For this study an experimental site with different residues management and mineral fertilization was established. The treatments were separated in two groups. The first one included the treatments with total or partial removal of forest residues: canopy (leaves and stems), bark and litter. The second group of treatment included the omission of nutrients in mineral fertilizer: N, P, K or lime. During eight years rotation were monitored soil fertility, biogeochemical cycling of nutrients, growth and tree nutritional status. The different residues management and mineral fertilizations has showed minor effects on soil fertility once the nutrient rates on soil were suitable due to the mineral fertilization applied for site preparation. However, when the fertilization was carried out without K, reduction of 50% in growth was observed. The omission of P in fertilization did not affect the wood productivity during the forest rotation, but P was the most limiting nutrient for the potential number of future rotations. The biochemical nutrient cycling was not affected by total or partial removal of forestry residues. Annual deposition of K was 60% reduced when the nutrient was not applied by fertilization, which affected the nutrient cycling. The results of this study demonstrated that despite the benefits of forest residues retention on chemical proprieties of soils, the inadequate fertilization reduces expressively the productive potential of the site.

Os objetivos deste estudo foram: estimar a produção e a decomposição de serapilheira, quantificar os macronutrientes, além de avaliar a estrutura da vegetação e a composição florística de uma floresta de várzea em uma região sob forte influência antrópica no sudoeste da Amazônia. O conhecimento destes processos é extremamente importante, uma vez que tais informações fornecem dados essenciais para estimar a produção líquida destes sistemas, sua ciclagem de nutrientes, além de auxiliar na recuperação de áreas degradadas através de planos de manejo adequados. As coletas de serapilheira foram realizadas quinzenalmente, durante o período de Setembro de 2005 a Agosto de 2007 e o experimento de decomposição foi realizado no período de um ano. O levantamento florístico e as medidas de estrutura florestal foram realizadas em campanha intensiva em Agosto de 2009. A produção média anual de serapilheira foi de 12,7 t ha-1, com elevado grau de sazonalidade, apresentando maior produção durante os meses mais secos do ano. A produção para as frações obedeceu à seguinte ordem: folhas >> galhos > miscelânea. O retorno médio anual de carbono via serapilheira foi de 5,4 t ha-1. Em termos de proporção, existem quase duas vezes mais carbono sendo depositado no período seco do que no chuvoso. A devolução média anual de N foi de 199,6 kg ha- 1.O grande retorno deste elemento está relacionado à elevada deposição de serapilheira. A eficiência na utilização de nutrientes (EUN) foi de 57,9, valor considerado relativamente baixo, indicando que o suprimento de nitrogênio não é limitante nesta floresta. A razão C:N foi alta para as duas etapas do experimento de decomposição, atingindo valor máximo no início da estiagem (40,0), influenciando o processo de decomposição, que foi relativamente lento, principalmente durante os meses mais secos do ano. O valor médio anual do coeficiente k foi de 0,9 para os litterbags e 0,7 para o método da serapilheira acumulada. Durante o processo de decomposição predominou a imobilização de N e houve liberação lenta de C. O balanço parcial de carbono indica que cerca de 342,3 kg ha-1 de carbono são liberados anualmente para outros compartimentos do ecossistema, representando cerca de 34,2% da troca líquida do ecossistema. Para o inventário florestal foram medidos todos os indivíduos com DAP > 3,2 cm, totalizando 2.170 indivíduos. As árvores com DAP < 20,0 cm representaram 49,1% do total da floresta. Foi observado decréscimo progressivo na concentração de indivíduos conforme o aumento do diâmetro, indicando que a população está estável e provavelmente, crescendo. Para a composição florística foram identificados 266 indivíduos com DAP > 10 cm, sendo observadas 43 espécies, 17 famílias, e 4 espécies não identificadas. As principais famílias encontradas foram Leguminoseae (30,2%), Palmae (9,3%), Anonaceae (7,0%) e Sapotaceae (7,0%). O índice de diversidade de Shannon-Winer (H) foi 3,2. A área basal foi de 24,3 m2 ha-1. Estes valores são similares aos encontrados em florestas na região sul/sudoeste da Amazônia, situando-se abaixo dos valores na Amazônia Central. Os menores valores de área basal implicam em menor biomassa florestal, e consequentemente, em menores emissões de CO2 nesta região em caso de queimadas / The objectives of this study were to estimate litterfall production and decomposition, macronutrients and to evaluate the structure and floristic composition of a varzea Forest in a region under strong anthropogenic influence in southwest Amazonia. Knowledge about these processes is extremely important, since they provide information on ecosystem net production, nutrient cycling and can serve as basis for degraded áreas restoration based on adequate management strategies. Litter was sampled biweekly from September 2005 to August 2007, while decomposition was measured during one year. Floristic survey and forest structure measurements were done in August 2009. Average annual litter production was 12.7 t ha-1, with strong seasonality and higher production during drier months. In terms of different litter fractions production followed the order leaves>>branches>miscellaneous. Average annual C deposition via litterfall was 5.4 t ha-1. Proportionally, almost twice as much C returns to the forest ground in the drier season. Average annual N deposition was 199.6 kg ha-1, which is related to relatively high litterfall deposition. Nutrient use efficiency (NUE) was 57.9, a value that can be considered relatively low, indicating that nitrogen supply is not a limiting factor in this forest. C:N ratios were high in both seasons, with maximum (40) occuring at the beginning of dry season, which probably influenced and promoted low decomposition rates, specially during drier months. Average annual k was 0.9 for litterbags and 0.7 based on litter accumulation. During decomposition N imobilization and slow C release predominated. Partial carbon budget indicates that around 342.3 kg C ha-1 are cycled via litterfall, representing 34.2% of net ecosystem exchange. For the forest inventory all individuals with diameter at the breast height (DBH) >3.2 cm were measured, totalling 2.170 individuals. Trees with DBH < 20.0 cm represent 49.1% of the forest. A progressive decrease in individuals as diameter size increase indicated that this forest is stable or even growing. The floristic composition was based on 266 individuals with DBH > 10 cm, composed of 43 species, 17 families and 4 unidentified species. Major families were Leguminoseae (30.2%), Palmae (9.3%), Anonaceae (7.0%) e Sapotaceae (7.0%). Shannon-Winer index (H) was 3.2. Basal area was 24.3 m2 ha-1. These values are similar to other findings in the south and southwest of the Amazon and lower than those of the central Amazon. Smaller basal area indicates smaller forest biomass and consequently smaller CO2 emission in case of fires in this region

Os objetivos deste estudo foram: estimar a produção e a decomposição de serapilheira, quantificar os macronutrientes, além de avaliar a estrutura da vegetação e a composição florística de uma floresta de várzea em uma região sob forte influência antrópica no sudoeste da Amazônia. O conhecimento destes processos é extremamente importante, uma vez que tais informações fornecem dados essenciais para estimar a produção líquida destes sistemas, sua ciclagem de nutrientes, além de auxiliar na recuperação de áreas degradadas através de planos de manejo adequados. As coletas de serapilheira foram realizadas quinzenalmente, durante o período de Setembro de 2005 a Agosto de 2007 e o experimento de decomposição foi realizado no período de um ano. O levantamento florístico e as medidas de estrutura florestal foram realizadas em campanha intensiva em Agosto de 2009. A produção média anual de serapilheira foi de 12,7 t ha-1, com elevado grau de sazonalidade, apresentando maior produção durante os meses mais secos do ano. A produção para as frações obedeceu à seguinte ordem: folhas >> galhos > miscelânea. O retorno médio anual de carbono via serapilheira foi de 5,4 t ha-1. Em termos de proporção, existem quase duas vezes mais carbono sendo depositado no período seco do que no chuvoso. A devolução média anual de N foi de 199,6 kg ha- 1.O grande retorno deste elemento está relacionado à elevada deposição de serapilheira. A eficiência na utilização de nutrientes (EUN) foi de 57,9, valor considerado relativamente baixo, indicando que o suprimento de nitrogênio não é limitante nesta floresta. A razão C:N foi alta para as duas etapas do experimento de decomposição, atingindo valor máximo no início da estiagem (40,0), influenciando o processo de decomposição, que foi relativamente lento, principalmente durante os meses mais secos do ano. O valor médio anual do coeficiente k foi de 0,9 para os litterbags e 0,7 para o método da serapilheira acumulada. Durante o processo de decomposição predominou a imobilização de N e houve liberação lenta de C. O balanço parcial de carbono indica que cerca de 342,3 kg ha-1 de carbono são liberados anualmente para outros compartimentos do ecossistema, representando cerca de 34,2% da troca líquida do ecossistema. Para o inventário florestal foram medidos todos os indivíduos com DAP > 3,2 cm, totalizando 2.170 indivíduos. As árvores com DAP < 20,0 cm representaram 49,1% do total da floresta. Foi observado decréscimo progressivo na concentração de indivíduos conforme o aumento do diâmetro, indicando que a população está estável e provavelmente, crescendo. Para a composição florística foram identificados 266 indivíduos com DAP > 10 cm, sendo observadas 43 espécies, 17 famílias, e 4 espécies não identificadas. As principais famílias encontradas foram Leguminoseae (30,2%), Palmae (9,3%), Anonaceae (7,0%) e Sapotaceae (7,0%). O índice de diversidade de Shannon-Winer (H) foi 3,2. A área basal foi de 24,3 m2 ha-1. Estes valores são similares aos encontrados em florestas na região sul/sudoeste da Amazônia, situando-se abaixo dos valores na Amazônia Central. Os menores valores de área basal implicam em menor biomassa florestal, e consequentemente, em menores emissões de CO2 nesta região em caso de queimadas / The objectives of this study were to estimate litterfall production and decomposition, macronutrients and to evaluate the structure and floristic composition of a varzea Forest in a region under strong anthropogenic influence in southwest Amazonia. Knowledge about these processes is extremely important, since they provide information on ecosystem net production, nutrient cycling and can serve as basis for degraded áreas restoration based on adequate management strategies. Litter was sampled biweekly from September 2005 to August 2007, while decomposition was measured during one year. Floristic survey and forest structure measurements were done in August 2009. Average annual litter production was 12.7 t ha-1, with strong seasonality and higher production during drier months. In terms of different litter fractions production followed the order leaves>>branches>miscellaneous. Average annual C deposition via litterfall was 5.4 t ha-1. Proportionally, almost twice as much C returns to the forest ground in the drier season. Average annual N deposition was 199.6 kg ha-1, which is related to relatively high litterfall deposition. Nutrient use efficiency (NUE) was 57.9, a value that can be considered relatively low, indicating that nitrogen supply is not a limiting factor in this forest. C:N ratios were high in both seasons, with maximum (40) occuring at the beginning of dry season, which probably influenced and promoted low decomposition rates, specially during drier months. Average annual k was 0.9 for litterbags and 0.7 based on litter accumulation. During decomposition N imobilization and slow C release predominated. Partial carbon budget indicates that around 342.3 kg C ha-1 are cycled via litterfall, representing 34.2% of net ecosystem exchange. For the forest inventory all individuals with diameter at the breast height (DBH) >3.2 cm were measured, totalling 2.170 individuals. Trees with DBH < 20.0 cm represent 49.1% of the forest. A progressive decrease in individuals as diameter size increase indicated that this forest is stable or even growing. The floristic composition was based on 266 individuals with DBH > 10 cm, composed of 43 species, 17 families and 4 unidentified species. Major families were Leguminoseae (30.2%), Palmae (9.3%), Anonaceae (7.0%) e Sapotaceae (7.0%). Shannon-Winer index (H) was 3.2. Basal area was 24.3 m2 ha-1. These values are similar to other findings in the south and southwest of the Amazon and lower than those of the central Amazon. Smaller basal area indicates smaller forest biomass and consequently smaller CO2 emission in case of fires in this region

Submitted by Rosivalda Pereira (mrs.pereira@ufma.br) on 2017-06-22T18:27:37Z No. of bitstreams: 1 ClemesonVale.pdf: 2109688 bytes, checksum: 66c1f271c7e5c2d788b9a17c44829c52 (MD5) / Made available in DSpace on 2017-06-22T18:27:37Z (GMT). No. of bitstreams: 1 ClemesonVale.pdf: 2109688 bytes, checksum: 66c1f271c7e5c2d788b9a17c44829c52 (MD5) Previous issue date: 2014-03-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / The constant concerns over the unsustainable use of natural resources, coupled with rapid population growth, direct them to the productive process of maximizing resources systems to provide greater increases in production to minimize impacts to the environment yields. The objective of this research was to evaluate the performance of maize in no-tillage in legume straw depending on the spatial variability of soil chemical properties and nutrient input in a Dystrophic cohesive oxisol. The experiment was conducted in a 0.6 ha area containing two environments (without legumes and pulses) and 170 sampling points regularly dispersed (7.0 x 5.0 m) for chemical soil variability and productive maize yields. Data were initially analyzed using descriptive statistics and later by geostatistical methods. The interaction between soil chemical properties and yield of corn production was assessed by Pearson correlation to 5%. There was an increase in levels of soil chemical properties in the area with legumes compared to the area without legumes, proving the applicability of this management system to improve the chemical quality of the soil due to continuous addition of plant residues. Found the presence of spatial variability for all soil chemical properties and productive yield with spatial dependence ranged from moderate to strong, allowing reveal through thematic maps the potentialities and limitations of the production system. The productive efficiency, productivity specifically, correlated positively with calcium, sum of bases, phosphorus, potassium, base saturation and cation exchange capacity. / As constantes preocupações com o uso insustentável dos recursos naturais, juntamente com o acelerado crescimento demográfico, direcionam os sistemas produtivos ao processo de maximização dos recursos a fim de proporcionar maiores incrementos nos rendimentos produtivos com minimização dos impactos ao ambiente. O objetivo da presente pesquisa foi avaliar o desempenho produtivo do milho em sistema de plantio direto na palha de leguminosas em função da variabilidade espacial dos atributos químicos do solo e do aporte de nutrientes num Latossolo Amarelo distrocoeso. O experimento foi conduzido numa área de 0,6 ha contendo dois ambientes (sem leguminosas e com leguminosas) e 170 pontos amostrais regularmente dispersos (7,0 x 5,0 m) para determinação da variabilidade química do solo e dos rendimentos produtivos do milho. Os dados foram inicialmente analisados por meio da estatística descritiva e posteriormente por métodos geoestatísticos. A interação entre os atributos químicos do solo e o rendimento produtivo do milho foi verificada pela correlação de Pearson a 5%. Verificou-se a elevação nos teores dos atributos químicos do solo na área com leguminosas quando comparado com a área sem leguminosas, comprovando a aplicabilidade desse sistema de manejo para a melhoria da qualidade química do solo em consequência da adição continuada de resíduos vegetais. Constatou-se a presença de variabilidade espacial para todos os atributos químicos do solo e rendimento produtivo, com grau de dependência espacial que variaram de moderado a forte, o que possibilitou revelar por meio de mapas temáticos as potencialidades e limitações do sistema de produção. O rendimento produtivo, especificamente a produtividade, apresentou correlação positiva com o cálcio, a soma de bases, o fósforo, o potássio, a saturação por bases e a capacidade de troca catiônica.