Arsenic is a naturally occurring element, which is toxic to aquatic biota especially in disturbed areas where it may be found at high concentrations. A headwater stream adjacent to an 85 year-old abandoned arsenic mine was investigated to determine the influence of arsenic on stream biota and processes using an upstream (reference) and downstream (mine-influenced) comparative approach. Arsenic concentration was measured monthly at 10 sites along the stream length. Benthic macroinvertebrate surveys were conducted in both reaches five times throughout the course of a year. Leaf breakdown assays were conducted in reference and mine-influenced reaches. Leaf biofilm respiration was recorded during leaf breakdown assays and also with experimental arsenic additions to reference reach leaf biofilms. At the field site, arsenic concentrations varied from below detection limit (<2.5µg/L) to more than 12 mg/L. Macroinvertebrate density was greatly reduced down-gradient of the mine with 154 individuals/m2, while upstream there were 7869 individuals/m2. Leaf biofilm respiration rates were comparable to others found in the literature and not significantly different between reference and mine-influenced reaches. Further, experimental additions of arsenic did not alter biofilm respiration under laboratory conditions. However, shredder abundance on leaf packs was eight to twenty times greater upstream than the mine-influenced reach. Leaf breakdown rate varied two to three fold among sites distributed above and below the mine and were significantly lower in reaches of elevated arsenic concentration. Together, these data suggest that the mining operations on this headwater stream have altered organic matter processing primarily by decreasing invertebrate densities and limiting shredder abundance. / Master of Science

The structure and function of stream ecosystems may be strongly influenced by land-use practices within watersheds. The magnitude of land-use impacts may depend upon the spatial arrangement of development in watersheds. This study examines the relationship between land-cover patterns and stream structure and function in 9 southern Appalachian headwater basins. Using a GIS/remote sensing approach, land-cover patterns were quantified at several spatial scales, including the entire watershed, riparian corridor, and riparian sub-corridors extending upstream in 200 m increments for 2 km. In-stream physico-chemical variables were related to land-cover patterns at different spatial scales. Dissolved constituents (e.g., TIN, alkalinity) were frequently related to physical features or land-cover patterns at the watershed scale. Conversely, mean substrate particle size and stream temperature were most strongly related to land-use practices at the entire riparian corridor scale. Finally, maximum stream temperature was best explained from land-cover patterns at the 200 m sub-corridor scale. The relationship between land-cover patterns and benthic macroinvertebrate communities is examined in Chapter 1. Macroinvertebrate assemblage structure was quantified using the slope of rank-abundance plots, and further described using standard diversity and evenness indices. Macroinvertebrate taxa richness ranged from 24 to 54 among sites, and the analysis of rank-abundance curves defined three distinct groups with high, medium, and low diversity. In general, other macroinvertebrate indices were in accord with rank-abundance groups, with richness and evenness decreasing among sites with maximum stream temperature. Macroinvertebrate indices were most strongly related to land cover patterns evaluated at the 200 m sub-corridor scale, suggesting local, streamside development effectively alters assemblage structure. The relationship between land-cover patterns and leaf breakdown is examined in Chapter 2. Breakdown rate for American sycamore (Plantanus occidentalis) leaf packs varied significantly among sites (k = 0.0051 to 0.0180 d-1), but fell within the range reported in the literature for sycamore. Leaf breakdown rate increased among sites with shredder density and biomass. Further, breakdown rate and shredder density and biomass were positively related to mean substrate particle size. Though several instream variables were related to watershed-scale features, leaf breakdown rate was not related to land cover at the watershed scale. Leaf breakdown rate was inversely related to % non-forest within riparian sub-corridors of approximately 1 km. Results suggest that the distribution of shredders is critical to leaf processing in these streams. In some streams, increased sediment inputs as a result of agricultural activity or residential development in riparian corridors may limit the distribution of shredders and thus influence leaf breakdown rates. Alternatively, near stream development may reduce the quantity and/or quality of allochthonous inputs to streams, and thus indirectly influence the distribution of shredders. / Master of Science

Land-use practices have long been associated with alterations in stream ecosystem structure and function, however, 'exurbanization' and its impact on streams is poorly understood. This study compares the ecosystem structure and function of 9 southern Appalachian streams of differing land-use (forested, exurban, agricultural). Impacts of land-use on leaf breakdown are examined in Chapter 1. Leaf breakdown rates were significantly related to land-use. Forested streams exhibited the slowest breakdown rates, followed by exurban streams, with agricultural streams having the fastest rates. Leaf breakdown was most strongly related to discharge (white oak) and some fine sediment metrics (red maple). Our results suggest that the altered hydrological regimes in agricultural streams, as well as the influx of fine sediments into streams from exurban development, can play a role in altering in-stream organic matter processing. The taxa and number of shredders present may play a role to a lesser extent. Impacts of land-use on macroinvertebrate assemblages are examined in Chapter 2. Shannon diversity, %EPT, and NCBI were significantly related to land-use regime. There were significant negative relationships between macroinvertebrate diversity and conductivity and temperature. In addition, biotic integrity had a significant negative relationship with conductivity. Canonical Correspondence Analysis (CCA) showed that agricultural streams were characterized by temperature and flow, forested streams by MPS and standing stock course particulate organic matter (SSCPOM), and two of three exurban streams by conductivity and temperature. Principal Coordinates Analysis (PCoA) revealed that while macroinvertebrate communities overlapped, some differences in community assemblage could be seen between land-use types. / Master of Science

Stream ecosystems can be influenced by cattle grazing in the riparian zone due to sediment input, nutrient loading, and soil compaction, which lead to alterations of macroinvertebrate and microbial activity. Recently government programs, such as the Conservation Reserve Enhancement Program (CREP), have provided funding for farmers to exclude cattle from streams and riparian zones. Funding for CREP is limited and does not allow for post exclusion assessment. The objectives for this study were; 1) to explore whether CREP and other cattle exclusion initiatives help restore functional integrity to streams; 2) and if they do, to evaluate the time required for integrity to be restored. I predicted leaf processing (a fundamental ecosystem level function) in streams would be influenced by excluding cattle from the riparian zone due to changes in nutrient availability, sediment abundance, shredding macroinvertebrates, and microbial activity. I tested this prediction by measuring leaf processing at sites that had cattle excluded for <1 to 15 years. Breakdown rates did not correspond linearly to time since cattle exclusion. This was probably due to the opposing effects of elevated sediment versus nutrients on leaf breakdown at recently grazed sites. Leaf breakdown and shredder density were strongly correlated with riparian vegetation density. This study suggests that in addition to cattle exclusion, reforestation of woody riparian vegetation may be essential to restore functional integrity to agricultural streams. / Master of Science

Mountaintop removal and valley fill (MTRVF) mining has become a widespread means of coal extraction in the central Appalachians. During MTRVF several hundred meters of overburden are removed to access coal seams, and excess rubble is dumped into adjoining valleys and streams. Filling valleys eliminates stream headwaters and may result in loss of stream ecosystem functions, which are dependent on temporal and lateral connectivity in river networks. To determine the affect of MTRVF on stream ecosystem function, leaf breakdown, which is an ecosystem level attribute of forested streams, was measured in five streams draining MTRVF sites and five reference streams in central West Virginia. Leaf packs of white oak and red maple were installed in these streams in December 2007, leaves were collected in January, February, March, April, and June of 2008, and leaves were washed and processed in the lab. Leaf breakdown rates were significantly slower in filled streams. MTRVF streams were marked by high sediment levels, elevated base flow, elevated conductivity and pH, and a lower density and richness of shredding macroinvertebrates than reference sites, suggesting that slower leaf decay was the result of the combined set of altered conditions in MTRVF streams. Additionally, MTRVF streams showed no species-level difference between red maple and white oak breakdown rates, indicating that MTRVF inhibits control of ecosystem function exerted by leaf species characteristics. / Master of Science

Central Appalachian headwater streams in coalfield areas are prone to mining disturbances, and compensatory mitigation is required in cases of documented impacts. Stream construction on reclaimed mines is a common mitigation strategy. Streams constructed as compensatory mitigation are meant to restore structural and functional attributes of headwater streams and are often evaluated by measuring structural ecosystem characteristics. However, replacement of stream ecosystem functions is essential for mitigation of mining disturbances from an ecosystem perspective. This research compared selected structural and functional measures in eight constructed streams on mined areas to those of four forested reference streams across two years. Three organic matter functions were evaluated: riparian litterfall input, leaf breakdown, and periphyton accrual. Constructed streams were typically warmer than reference streams and also had elevated specific conductance, elevated oxidized nitrogen concentrations, depressed benthic macroinvertebrate richness, and lower levels of canopy cover. Functionally, litterfall input and total leaf breakdown means for constructed streams were approximately 25% and 60% of reference means, respectively. Leaf breakdown in constructed streams appeared to be inhibited as a result of reduced processing by benthic macroinvertebrates as well as inhibition of microbial and physicochemical pathways. Constructed streams with total breakdown rates most similar to reference-stream levels had the coldest stream temperatures. Areal periphyton biomass, benthic algal standing crop, and senescent autotrophic organic matter in constructed streams were roughly quadruple, double, and quintuple those of reference streams, respectively. Indicator ratios also suggested stream-type differences in periphyton structure. Mean algal accrual was greater in constructed streams than in reference streams during leaf-on seasons. My results suggest that light is likely the primary factor driving accrual rate differences during summer and fall, but that temperature may also be important during fall. Planting a diverse assemblage of native riparian trees and ensuring their successful development can inhibit benthic irradiance and thermal energy inputs while providing similar quantity and quality of OM to constructed streams, thereby fostering replacement of reference-like OM functions in some streams. / Ph. D.

Streams and terrestrial ecosystems are linked through allochthonous organic matter inputs from streamside vegetation. This allochthonous material makes up the energy base for forested aquatic food webs. Therefore, removal of riparian vegetation associated with agricultural land use affects stream ecosystem structure and function. The objectives of this study were to measure and compare allochthonous input and leaf breakdown rates along a gradient of agricultural land use in southern Appalachian streams. Study streams were placed into the following land use categories: forest and light, moderate, and heavy agriculture. Several physical, chemical, and biological parameters also were measured including discharge, temperature, nutrient concentrations, macroinvertebrate abundance and density, periphyton biomass, and chlorophyll a concentration. In forested, light agricultural, and moderate agricultural streams, the quantity and quality of allochthonous input were not significantly different. However, the timing and composition of allochthonous materials were related to land use. Chlorophyll a and periphyton biomass did not vary among land use types. Leaf breakdown rates were significantly faster in light and moderate agricultural streams in comparison to forested and heavy agricultural streams. Slow breakdown rates in forested streams resulted from low nutrient concentration and cool stream temperature. The scarcity of shredding macroinvertebrates and sedimentation probably limited leaf breakdown in heavy agricultural streams. Though limited riparian vegetation along agricultural streams resulted in an energy supply equivalent to forested streams, agricultural land use may still have long term impacts on stream structure including nutrient concentrations, temperature, macroinvertebrate community, and sedimentation thus affecting stream ecosystem function. / Master of Science

Made available in DSpace on 2016-06-02T19:32:08Z (GMT). No. of bitstreams: 1 5535.pdf: 7207431 bytes, checksum: 523a8fec3f0f24a0756174126c56beba (MD5) Previous issue date: 2013-08-29 / Universidade Federal de Sao Carlos / Lotic systems are highly influenced by the landscape through which they flow, and changes in the landscape are the main threat to their ecological integrity. Evaluating the ecological "health" of lotic systems is essential and of great importance to the management of water resources worldwide. In this study, we evaluated the integrity of streams in southeastern Brazil using the protocol WHEBIP (Watershed Habitat Evaluation and Biotic Integrity Protocol), which combines information about the coverage of riparian vegetation, geomorphology, land cover and human activities to assess the physical characteristics of the sub-basin and to evaluate the integrity of streams. We compared this protocol with the protocol RCE (Riparian, Channel and Environmental), already widely used in tropical regions, to directly assess stream physical condition. As a measure of the functional integrity of streams, we estimated leaf breakdown rates, an important process in lotic systems. Furthermore, we sorted and identified the macroinvertebrates that colonized leaves in the 2nd and 28th days of the decomposition experiment and calculated environmental quality metrics related to these communities to test their relationship with WHEBIP. The protocols WHEBIP and RCE were significantly correlated to each other, with greater differentiation among streams especially when RCE was high. Possibly, the WHEBIP, by incorporating spatial variables on a large scale in the landscape, best differentiates these streams. None of the protocols tested were correlated with leaf breakdown rates. However, when calculating variation of decay rates (standard error), we observed a positive relationship with the protocol WHEBIP. Thus, we grouped the metrics of the protocol WHEBIP in a Principal Component Analysis (PCA), noting the trend to a significant correlation between changes in leaf breakdown rates and the first axis of the PCA, which indicates that the increase of forest cover in the microbasin could reduce variation in leaf breakdown rates in streams. The WHEBIP and RCE showed no correlation with the environmental quality metrics related to macroinvertebrate communities. But we tested the hypothesis that higher values of WHEBIP decreases the variation in leaf breakdown rates due to higher stability of macoinvertebrate communities, we found a significant correlation to withdraw one of the streams of the analysis. This stream differed greatly from the rest, because even getting down in value in WHEBIP, showed a differentiation between communities, due to the dominance of certain taxa in the days analyzed. This is the first study in the tropics that relates the variation in leaf breakdown rates in streams and forest cover of the microbasin within they are inserted. Our results suggest that WHEBIP protocol can be used to assess the integrity of streams in tropical regions. This protocol showed significant relationships with the variation in leaf breakdown rates, which may prove to be an interesting metric for use in monitoring, and the stability of the macroinvertebrate community, which is greater in less impacted streams, as suggested by other studies. / Os sistemas lóticos são extremamente influenciados pela paisagem através da qual fluem, e as transformações na paisagem são a principal ameaça à sua integridade ecológica. Avaliar a saúde ecológica dos sistemas lóticos é fundamental e de grande importância para o manejo dos recursos hídricos em todo o mundo. Neste estudo, avaliamos a integridade de córregos no sudeste brasileiro utilizando o protocolo WHEBIP (Watershed Habitat Evaluation and Biotic Integrity Protocol), que combina informações sobre a cobertura de vegetação ripária, geomorfologia, cobertura da terra e atividades humanas para avaliar as características físicas da sub-bacia e estimar a integridade de córregos. Comparamos esse protocolo com o protocolo RCE (Riparian, Channel and Environmental), já bastante utilizado em regiões tropicais, para avaliação física direta dos córregos. Como medida da integridade funcional dos córregos, estimamos a taxa de decomposição foliar, importante processo nos sistemas lóticos. Além disso, triamos e identificamos os macroinvertebrados que colonizaram as folhas referentes ao 2º e ao 28º dias do experimento de decomposição e calculamos métricas de qualidade ambiental relacionadas às comunidades desses organismos, para testar sua relação com o WHEBIP. Os protocolos WHEBIP e RCE foram significativamente correlacionados entre si, havendo maior diferenciação entre os córregos principalmente quando o RCE foi alto. Possivelmente o WHEBIP, por incorporar variáveis espaciais em uma escala maior na paisagem, diferencia melhor esses córregos. Nenhum dos protocolos testados apresentou correlação com as taxas de decomposição. No entanto, ao calcularmos a variação das taxas de decomposição (erro padrão), observamos uma relação positiva com o protocolo WHEBIP. Assim, agrupamos as métricas do protocolo WHEBIP em uma Análise de Componentes Principais (PCA), observando tendência a uma correlação significativa entre a variação das taxas de decomposição e o primeiro Eixo da PCA, o que indica que o aumento da cobertura florestal na microbacia poderia reduzir a variação nas taxas de decomposição foliar nos córregos. O WHEBIP e o RCE não apresentaram correlações com as métricas de qualidade ambiental relacionadas às comunidades de macroinvertebrados. Mas ao testarmos a hipótese de que os maiores valores do WHEBIP diminuiriam a variação das taxas de decomposição devido a maior estabilidade das comunidades de macroinvertebrados, encontramos uma correlação significativa ao retirarmos um dos córregos das análises. Esse córrego diferenciava-se bastante do restante, pois mesmo obtendo baixo valor no protocolo WHEBIP, apresentou uma baixa diferenciação entre as comunidades, devido à dominância de alguns táxons nos dias analisados. Este é o primeiro trabalho para os trópicos que relaciona a variação nas taxas de decomposição foliar nos córregos e a cobertura florestal das microbacias em que estão inseridos. Nossos resultados sugerem que o protocolo WHEBIP pode ser utilizado para avaliar a integridade de córregos em regiões tropicais. Esse protocolo apresentou relações significativas com a variação nas taxas de decomposição, que pode vir a ser uma métrica interessante para o uso em monitoramento, e com a estabilidade da comunidade de macroinvertebrados, que é maior em córregos menos impactados, conforme sugerido por outros estudos.

Em riachos de cabeceira florestados, o aporte de material vegetal da zona ripária é de suma importância, pois sua decomposição disponibiliza nutrientes para um sistema de baixa produtividade primária. Mudanças no uso do solo têm forte influência na abundância e composição do material vegetal alóctone disponível para decomposição, alterando fontes e fluxos de nutrientes. Os macroinvertebrados atuam na decomposição como organismos fundamentais na conversão da matéria orgânica grossa em matéria orgânica fina. Neste contexto, este estudo teve como objetivo investigar a colonização e a função dos macroinvertebrados aquáticos na decomposição foliar. Foram selecionados dois riachos na Serra do Mar, SP, sendo um em área de floresta e outro em área de pastagem, onde foram instalados litter bags preenchidos com Mollinedia schottiana, Brachiaria brizantha (gramínea) ou a mistura das espécies. Estes foram dispostos no fundo dos riachos e coletados temporalmente aos 7, 17, 31, 63 e 91 dias após suas instalações. Os invertebrados foram identificados, quantificados e classificados em grupos funcionais e o material vegetal foi seco e determinado seu peso remanescente. Em seguida, foi realizada a análise isotópica dos macroinvertebrados encontrados e das suas possíveis fontes alimentares, sendo calculada também a contribuição dos produtores primários em suas dietas. Os resultados mostram uma decomposição mais rápida da gramínea na área de floresta e da M. schottiana na pastagem. Maiores abundâncias e densidades de macroinvertebrados foram encontradas na pastagem e nas gramíneas, sendo a densidade inversamente proporcional ao peso remanescente. A riqueza foi similar entre os riachos e tratamentos e a diversidade foi superior na área florestal. Chironomidae foram os mais abundantes em ambos os riachos e tratamentos, sendo responsáveis por mais de 50% do total de indivíduos. Trichoptera foram mais abundantes na floresta e nos tratamentos com a M. schottiana. Amphipoda foram encontrados apenas na floresta. Coletores, fragmentadores e predadores, de modo geral, foram os principais grupos tróficos encontrados, sendo os fragmentadores mais representativos nas coletas iniciais, destacando-se principalmente na floresta e nos tratamentos com a M. schottiana. Os valores isotópicos na pastagem se mostraram mais enriquecidos, tanto com relação ao 13C quanto ao 15N. Os valores isotópicos dos macroinvertebrados indicaram baixa contribuição das gramíneas (C4) em sua dieta, podendo destacar a maior influência de M. schottiana (C3) na floresta enquanto que, na pastagem, maior influência de perifiton e M. schottiana (C3). Assim, pode-se reforçar papel da vegetação ripária para os riachos, sendo sua conservação de grande importância na transferência de matéria e energia nesses ecossistemas e outros adjacentes / In forested headwaters, the plant material input from the riparian zone is very important, as its decomposition provides nutrients for a low primary production system. Land use changes have a great influence in the abundance and composition of allochthonous plant material available for decomposition, altering nutrients sources and fluxes. The macroinvertebrates act in the decomposition process as key organisms at the conversion of coarse organic matter into fine organic matter. In this context, this study aimed to investigate the colonization and the role of aquatic macroinvertebrates in leaf breakdown. Two streams of the Serra do Mar, SP, were selected, one at a forest area and the other at a pasture area, where litter bags filled with Mollinedia schottiana, Brachiaria brizantha (grass) or a mixture of species were installed. These were placed at the bottom of streams and collected periodically (7, 17, 31, 63 and 91 days).Invertebrates were identified, quantified and ranked into functional groups while plant material was dried for determination of its remaining dry weight. Then, the isotopic analyzes were performed for the found macroinvertebrates and its possible food sources, and it was also calculated the contribution of the primary producers in their diets. The results show faster breakdown of the grass at the forest area and of Mollinedia schottiana at the pasture. Greater macroinvertebrates abundance and density were found in the pasture and in the grass, being the density inversely proportional to the remaining weight. Richness was similar between streams and treatments and the diversity was higher at the forest. Chironomidae were the most abundant in both streams and treatments, being responsible for more than 50% of all individuals. Trichoptera were more abundant at the forest and in treatments with Mollinedia schottiana, while Amphipoda were found only in the forest. Collectors, shredders and predators, in general, were the main functional trophic group found and shredders were more representative in the first samplings, mainly at the forest and in treatments with Mollinedia schottiana. The pasture was more isotopically enriched, both in relation to 13C as to 15N. The isotopic values of macroinvertebrates indicated low grasses (C4) contribution in their diet, what can highlight the higher influence of Mollinedia schottiana (C3) in the forest and periphyton and Mollinedia schottiana (C3) in the pasture. Thus, it can enhance the role of riparian vegetation to the streams, and the importance of its conservation for the transfer of matter and energy process at these ecosystems and other adjacent systems

Made available in DSpace on 2016-06-02T19:32:03Z (GMT). No. of bitstreams: 1 4456.pdf: 1247547 bytes, checksum: ea5094b8a857fd0fd716f021fd9cf991 (MD5) Previous issue date: 2012-05-18 / Financiadora de Estudos e Projetos / Riparian ecosystems are being rapidly degraded due to deforestation for conversion of natural areas to agriculture, pasture, and urban development. In rural areas, riparian forest remnants can be very important for biodiversity conservation and for the maintenance and improvement of water physical and chemical characteristics as the deforested stream passes through these remnants. Here, we evaluated whether distance from the forest edge and forest structure influenced stream water physical and chemical characteristics and leaf breakdown rates, a measure of ecosystem function. Sampling was carried out from 150 m outside the remnant until 600 m inside the forest remnant. Water physical and chemical characteristics, leaf breakdown rates and riparian forest structure were evaluated at 50 m intervals until 300 m inside the remnant, and then each 100 m. Forest structure was evaluated by mean diameter at breast height, total basal area, mean canopy height, tree stratification, and tree density per plot; the variables were later reduced to the first two axes of a Principal Components Analysis (PCA), representing two gradients, 1) forest stratification vs. tree size, and 2) tree density vs. basal area. Electric conductivity and ammonium concentrations reduced as the stream passed through the remnant, whereas dissolved oxygen, total phosphorus, total dissolved P, organic P, silicate concentrations, and leaf breakdown rates increased along the remnant, as determined by first-order exponential models. Residual variation of these models was regressed against the first two PCA axes of forest structure. More stratified parts of the forest, with smaller trees, resulted in lower electric conductivity values and concentrations of total nitrogen and nitrite, whereas higher density of trees resulted in lower levels of total and dissolved P, but higher rates of leaf breakdown. This suggests that the distribution of fragments with different qualities of forest, with different structures possibly influences the quality of the water stream on a scale of watersheds. / Ecossistemas ripários vêm sendo rapidamente degradados devido ao desmatamento resultante da conversão de áreas naturais para agropecuária e desenvolvimento urbano. Em áreas rurais, remanescentes de florestas podem ter grande importância para a conservação da biodiversidade e para a manutenção e melhoria das características físicas e químicas da água de córregos que cortam estes remanescentes. Neste estudo avaliamos se a distância a partir da borda da floresta e a estrutura da floresta influenciaram as características físicas e químicas da água do córrego e as taxas de decomposição foliar, uma medida da função do ecossistema. Realizamos a amostragem a partir de 150 m fora do fragmento florestal até 600 m no interior do mesmo. Avaliamos as características físicas e químicas da água, as taxas de decomposição foliar e a estrutura da floresta ripária em intervalos de 50 m até atingir 300 m no interior do fragmento, a partir daí realizamos a avaliação a cada 100 m. Avaliamos a estrutura da floresta através das medidas do diâmetro médio à altura do peito, área basal total, altura média do dossel, estratificação e densidade de árvores por trecho, e as variáveis foram posteriormente reduzidas aos dois primeiros eixos da Análise de Componentes Principais (ACP), representando dois gradientes: 1) estratificação da floresta versus tamanho das árvores, e 2) densidade de árvores versus área basal. A condutividade elétrica e as concentrações de amônio diminuiram à medida que o córrego passou ao longo do fragmento, enquanto as concentrações de oxigênio dissolvido, fósforo total, fosfato total dissolvido, fosfato orgânico e silicato, e as taxas de decomposição foliar aumentaram ao longo do fragmento, conforme determinado pelos modelos exponenciais de primeira ordem. Os resíduos destes modelos foram usados em um modelo de regressão linear com os dois primeiros eixos da ACP da estrutura da vegetação. Os trechos mais estratificados da floresta e com árvores menores, resultaram em menores valores da condutividade elétrica e das concentrações de nitrogênio total e nitrito, enquanto maior densidade de árvores resultaram em baixos níveis de fósforo total e fosfato total dissolvido, mas taxas de decomposição foliar mais elevadas. Isto sugere que a distribuição de fragmentos com qualidades da floresta diferentes, ou seja, com estruturas diferentes possivelmente influencia a qualidade da água do córrego em uma escala de bacias hidrográficas.