Submitted by Jordan (jordanbiblio@gmail.com) on 2017-05-05T13:55:14Z No. of bitstreams: 1 DISS_2015_Magdiel Josias do Prado.pdf: 1377746 bytes, checksum: c0558030ad829d4b3388055267457759 (MD5) / Approved for entry into archive by Jordan (jordanbiblio@gmail.com) on 2017-05-18T16:23:32Z (GMT) No. of bitstreams: 1 DISS_2015_Magdiel Josias do Prado.pdf: 1377746 bytes, checksum: c0558030ad829d4b3388055267457759 (MD5) / Made available in DSpace on 2017-05-18T16:23:32Z (GMT). No. of bitstreams: 1 DISS_2015_Magdiel Josias do Prado.pdf: 1377746 bytes, checksum: c0558030ad829d4b3388055267457759 (MD5) Previous issue date: 2015-02-23 / CNPq / O Pantanal norte de Mato Grosso é caracterizado por quatro períodos sazonais: a enchente, a cheia, a vazante e a seca. Esses períodos determinam uma intensa variação na disponibilidade de água e no grau de oxigenação do solo da região, agindo como um filtro seletivo que permite que somente as espécies com capacidade de adaptação consigam ali sobreviver. Considerando esses aspectos, o objetivo com esta pesquisa foi o de analisar a capacidade adaptativa de duas espécies do gênero Combretum, o C. lanceolatum Pohl ex Eickl e o C. laxum Jacq, que figuram como espécies invasoras na região. Dois aspectos fisiológicos foram levados em consideração para tal avaliação, o intercâmbio gasoso e as relações hídricas. Para ambos os aspectos analisados foram medidas as variáveis inerentes em cada um dos quatro períodos sazonais. Para as medições de intercâmbio gasoso foi utilizado um analisador de gás infravermelho portátil, modelo LI-6400 (LI-COR, Inc., Lincoln, NE, USA) e para análise das relações hídricas foi utilizado uma bomba de pressão do tipo Scholander. Observou-se que a sazonalidade climática, afetou de forma particular o intercambio gasoso das espécies em estudo. Apesar de ambas as espécies ocorrerem de forma extensiva no Pantanal, o que por si é um indicador da adaptabilidade das mesmas ao local, as estratégias fisiológicas adotadas pelas mesmas são diferentes. Do ponto de vista da assimilação do carbono, enquanto o período de vazante causa redução na taxa fotossintética de C. lanceolatum, é o período seco que causa esse mesmo efeito no C. laxum. Enquanto a redução na taxa fotossintética líquida no C. laxum pode estar associada a um efeito estomático, porque nesse período, independentemente das espécies, é quando se verifica o menor valor da condutância estomática; para o C. lanceolatum a redução deve estar mais relacionada com aspectos não estomáticos. Nas relações hídricas observou-se que a capacidade de ressaturação de ambas as espécies variou com a sazonalidade, sendo mais efetivos durante os períodos de enchente e cheia e menos efetivos durante a vazante e a seca. Ambas as espécies não apresentaram variações significativas do conteúdo relativo de água a plena turgência e do módulo volumétrico de elasticidade da parede celular. As variações no potencial osmótico à turgescência plena e à turgescência insipiente não revelam claramente a busca por um ajuste sazonal dessas variáveis. Aparentemente a relativa constância dos valores das variáveis das relações hídricas verificada para ambas as espécies ao longo dos períodos sazonais sugere uma adaptação à qualquer variação extrema na disponibilidade de água no ambiente. / The North Pantanal of Mato Grosso is characterized by four seasonal periods: the flood, full, the ebb and dry. These periods determine an intense variation in water availability and the degree of oxygenation of the soil of the region, acting as a selective filter that allows only the species with adaptability able to survive there. Considering these aspects, the aim of this study was to analyze the adaptive capacity of two species of the genus Combretum, C. lanceolatum Pohl ex Eickl and C. laxum Jacq, listed as invasive species in the region. Two physiological aspects were taken into account in this assessment, the gas exchange and water relations. For both aspects analyzed were measured variables inherent in each of the four seasonal periods. For gas exchange, measurement was performed using a portable infrared gas analyzer, Model LI-6400 (Li-COR Inc., Lincoln, NE, USA) and water relations analysis was used a pressure type pump Scholander. It was observed that the seasonality, affected in a particular way the gas exchange of the species studied. Although both species occur extensively in the Pantanal, which in itself is an indicator of the adaptability of the same location, the physiological strategies adopted by them are different. Carbon assimilation of view, while the ebb period causes a reduction in photosynthetic rate of C. lanceolatum, is the dry season, which causes the same effect on C. laxum. While the reduction in net photosynthetic rate in C. laxum may be associated with a stomatal effect because this period, regardless of species, when there is the lowest value of stomatal conductance; for C. lanceolatum the reduction must be more related to aspects not stomatal. In water relations noted that the resaturation capacity of both species with varied seasonally, being more effective during flood periods and full and less effective during ebb tide and dried. Both species showed no significant changes in relative water content at full turgor and bulk modulus of elasticity of the cell wall. Changes in osmotic potential at full turgor and swelling incipient not clearly reveal the search for a seasonal adjustment of these variables. Apparently, the relative constancy of variable water relations values observed for both species along seasonal periods suggests an adaptation to any extreme variation in water availability in the environment.

Resumo parte 1: A invasão biológica é uma das principais ameaças à biodiversidade em todo o mundo. Entretanto, apesar dos trópicos concentrarem a maior parcela desta diversidade, ainda é pouco e esparso o conhecimento científico disponível sobre plantas invasoras nos ecossistemas tropicais. Este capítulo tem como objetivo comparar a quantidade de trabalhos publicados sobre invasões biológicas por plantas terrestres em ambientes tropicais e não tropicais, assim como a abordagem seguida nesses artigos. Foram lidos, selecionados e revisados os artigos publicados no intervalo de 1995 a 2004, em oito revistas científicas de alto índice de impacto. Ao todo, foram encontrados 239 artigos sobre plantas invasoras, sendo que a maioria deles aborda ecossistemas da América do Norte e Europa. Este é um reflexo do desequilíbrio na produção científica atual, que não dá a devida atenção aos ambientes com a maior biodiversidade, sendo que esta recebe vários tipos de ameaças à sua conservação. Resumo parte 2: As palmeiras da espécie Archontophoenix cf. cunninghamiana são invasoras em um pequeno fragmento florestal na região metropolitana da cidade de São Paulo (SP). Este trabalho investigou a abundância das sementes dessa espécie na chuva e no banco de sementes nesse local. Foram coletadas cinqüenta amostras de solo e de sementes da chuva de sementes em doze coletas mensais. Os resultados indicam que a dispersão de sementes dessa espécie invasora é efetiva na mata e que há a possibilidade dessa espécie formar um banco de sementes sazonal. Portanto, o sucesso da invasão poderia ser explicado pela capacidade de dispersão dessa espécie na mata, assim como por outras características da espécie e pela baixa resistência à invasão da comunidade neste fragmento. / Biological invasion is one of the worst threats to the world biodiversity. The actual extent of the impact of biological invasions in the tropics is still unknown. The aim of this chapter is to survey the literature published on plant invasions, comparing the material concerning the tropics with that regarding the rest of the world. 239 articles published in 8 ecological journals over the past ten years were reviewed. Most of them focused on temperate ecosystems, in North America and Europe. There is a weak effort on research concerning plant invasions in tropical ecosystems. Much more research is needed to evaluate the real scenario in the countries that contain the highest biodiversity of the world. The exotic palm Archontophoenix cf. cunninghamiana invaded a small forest fragment in São Paulo (São Paulo, Brazil). The abundance of this species in the seed rain and seed bank were investigated. The results indicate that this species may form a seasonal seed bank in the soil and that the seed dispersal is effective in the community. The success of the invasion by this exotic palm can be attributed to its high dispersal ability and to the community high invasibility due to the isolation of the forest fragment.

A atividade de restauração florestal é freqüentemente realizada em áreas degradadas, ocupadas por gramíneas exóticas invasoras, e o controle destas plantas é fator determinante no sucesso da restauração. Esta pesquisa tem o objetivo de testar intervenções para controle da gramínea exótica invasora Urochloa decumbens Stapf. em área de restauração florestal, com plantio de mudas nativas em área total. O delineamento utilizado foi o de blocos com parcelas subdivididas. Os tratamentos aplicados nas parcelas foram: 1. Não inversão de solo (R) e 2. Com inversão de solo por gradagem (G). Os tratamentos aplicados nas subparcelas foram: 1. Aplicação de herbicida na instalação e nas manutenções (H), 2. Plantio de feijão de porco (Canavalia ensiformes DC.) com aplicação de herbicida na instalação e nas manutenções só roçagem (H+FP), 3. Plantio de feijão de guandu (Cajanus cajan L.) com aplicação de herbicida na instalação e nas manutenções só roçagem (H+FG), 4. Plantio de feijão de porco (Canavalia ensiformes DC.) na instalação e nas manutenções só roçagem (FP), 5. Plantio de feijão de guandu (Cajanus cajan L.) na instalação e nas manutenções só roçagem (FG), 6. Roçagem na instalação e nas manutenções (sem aplicação de herbicida e sem plantio de adubos verdes) (s/Hs/AV). O desenvolvimento da gramínea foi avaliado pela altura e porcentagem de cobertura no solo e o desenvolvimento das mudas pela altura, área de copas e mortalidade. As analises estatísticas foram realizadas pelo pacote estatístico SAS. O experimento permitiu concluir que, no período entre plantio e a primeira manutenção (realizada 3 meses após o plantio) as coberturas vivas na interação R(H+FP) e R(H+FG) diminuíram a porcentagem de cobertura no solo de U. decumbens em relação ao tratamento R(s/Hs/AV) e os tratamentos (H+FP) e (H+FG) diminuíram a altura da U. decumbens no primeiro mês em relação ao tratamento (s/Hs/AV). Após a primeira manutenção, apenas o tratamento (H) diminuiu a porcentagem de cobertura no solo de U. decumbens e a altura desta gramínea em relação a todos os demais. Nas variáveis referentes ao desenvolvimento das mudas, apenas a variável área de copas apresentou diferença significativa nas interações entre os tratamentos R(H) e R(s/Hs/AV) 7 meses após o plantio e R(H) em relação a todos os demais 9 meses após o plantio, sendo que o R(H) apresentou maior área de copas. Neste experimento, o uso de adubos verdes em área de restauração florestal não melhorou o desenvolvimento das mudas plantadas. O tratamento que promoveu menor porcentagem de cobertura no solo de U. decumbens, menor altura de Urochloa decumbens Stapf. e mudas com maior área de copas foi o que teve aplicação de herbicida na instalação e nas manutenções (H). / The activity of forest restoration is often performed in areas covered by exotic grasses. In this way, the weed control of these plants is a determining factor in the success of restoration. This project aims to test different interventions for Urochloa decumbens Stapf. control in an area of forest restoration with seedlings planting in total area. The design adopted was split plot treatments divided in blocks, with each plot with different kind of soil tillage systems: 1. tillage (no soil movement) and 2. Harrowing (ground motion); and subplots with: 1. herbicide application in the installation and during maintenance (H); 2. herbicide application and planting of bean (Canavalia ensiformis DC.) in the installation and maintenance on mowing (FP + H); 3. herbicide application and planting beans (Cajanus cajan L.) in the installation and maintenance on mowing (H + FG); 4. planting bean (Canavalia ensiformis DC.) in the installation and maintenance on mowing (FP), 5. planting bean (Cajanus cajan L.) in the installation and maintenance on mowing (FG); and 6. no herbicide application nor planting green manure in the installation and the maintenance on mowing (s / Hs / AV). The grass height and percentage of occupation in of the soil was measured, as well the height, canopy area and mortality of seedlings, all of them analyzed by the SAS statistical package. In the period between planting and first maintenance (3 months), the living roofs in the interaction R (H + FP) and R (H + FG) controlled the percentage of invasive exotic grasses in the soil, and the treatments (H + FP) and ( H + FG) controlled the height of grasses in the first month. After the first maintenance, only the treatment (H) controlled the grasses in percentage of occupancy in the soil and height. Regarding the variables referred to the seedlings, only the canopy area showed a significant difference between treatments (H) and (s / Hs / AV) 7 months after planting and the (H) treatment showed a difference among all others, 9 months after planting,, as well its showed the biggest area. In this experiment the use of green manure in the area of forest restoration did not improve seedling growth. The (H) treatment was the one that promotes the Urochloa decumbens Stapf. control for a longer time and the seedlings with the largest canopy area.

Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Extensive areas of the Eastern Cape Province have been invaded by Pteronia incana (Blue bush), a non-palatable patchy invader shrub that is associated with soil degradation. This study sought to establish the relationship between the invasion and a range of eco-physical and land use gradients. The impact of the invader on soil moisture flux was investigated by comparing soil moisture variations under grass, bare and P. incana invaded surfaces. Field based and laboratory spectroscopy was used to validate P. incana spectral characteristics identified from multi-temporal High Resolution Imagery (HRI). A belt transect was surveyed to gain an understanding of the occurrence of the invasion across land use, isohyetic, geologic, vegetation, pedologic and altitudinal gradients. Soil moisture sensors were calibrated and installed under the respective surfaces in order to determine soil moisture trends over a period of six months. To classify the surfaces using HRI, the pixel and sub-pixel based Perpendicular Vegetation Index (PVI) and Spectral Mixture Analysis (SMA) respectively were used. There was no clear trend established between the underlying geology and P. incana invasion. Land disturbance in general was strongly associated with the invasion, as the endemic zone for the invasion mainly comprised abandoned cultivated and overgrazed land. Isohyetic gradients emerged as the major limiting factor of the invasion; a distinct zone below 619mm of mean annual rainfall was identified as the apparent boundary for the invasion. Low organic matter content identified under invaded areas was attributed to the patchy nature of the invader, leading to loss of the top soil in the bare inter-patch areas. The area covered by grass had consistently higher moisture values than P. incana and bare surfaces. The difference in post-rainfall moisture retention between grass and P. incana surfaces was significant up to about six days, after which a near parallel trend was noticed towards the ensuing rainfall episode. Whereas a higher amount of moisture was recorded on grass, the surface experienced moisture loss faster than the invaded and bare surfaces after each rainfall episode. ii There was consistency in multi-temporal Digital Number (DN) values for the surfaces investigated. The typically low P. incana reflectance in the Near Infrared band, identified from the multi-temporal HRI was validated by field and laboratory spectroscopy. The PVI showed clear spectral separability between all the land surfaces in the respective multi-temporal HRI. The consistence of the PVI with the unmixed surface image fractions from the SMA illustrates that using HRI, the effectiveness of the PVI is not impeded by the mixed pixel problem. Results of the laboratory spectroscopy that validated HRI analyses showed that P. incana’s typically low reflectance is a function of its leaf canopy, as higher proportions of leaves gave a higher reflectance. Future research directions could focus on comparisons between P. incana and typical green vegetation internal leaf structures as potential causes of spectral differences. Collection of spectra for P incana and other invader vegetation types, some of which have similar characteristics, with a view to assembling a spectral library for delineating invaded environments using imagery, is another research direction.

Orientadores: Bárbara Janet Teruel Mederos, Neucimar Jerônimo Leite / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola / Made available in DSpace on 2018-08-27T18:36:30Z (GMT). No. of bitstreams: 1 Santiago_WesleyEsdrar_D.pdf: 3166190 bytes, checksum: 2b92c9e10c657873f3a49bbd80582db3 (MD5) Previous issue date: 2015 / Resumo: O aumento da produção sem causar danos ao meio ambiente é um dos maiores desafios da agricultura moderna. Na produção de cana-de-açúcar, isso se torna mais nítido quando se trata do manejo de plantas daninhas, uma vez que o uso de herbicidas configura-se como a técnica mais adotada. Plantas daninhas causam interferência na produção agrícola, provocando redução na qualidade do produto e na produtividade da lavoura. Portanto, a identificação da espécie infestante, bem como o nível de infestação torna-se de grande importância para que estratégias adequadas de manejo possam ser definidas. Este trabalho foi realizado visando desenvolver e avaliar o desempenho de um sistema de processamento de imagens RGB, para identificar plantas daninhas na cultura de cana-de-açúcar e estimar a área de solo coberta por elas, uma vez que a existência de uma ferramenta computacional para reconhecimento de espécies de plantas é de grande auxílio para a tomada de decisão acerca do manejo de comunidades infestantes. A abordagem adotada para identificar plantas daninhas e cultura, baseou-se na metodologia do dicionário de palavras. Nesta metodologia, pontos invariantes e característicos de várias imagens são usados para criar um dicionário de características, o dicionário é usado depois para averiguar quais palavras dele estão presentes nas imagens a serem processadas. A quantização do número de palavras do dicionário presentes na imagem foi realizada através de uma função densidade de probabilidade e o modelo matemático de classificação foi construído por meio de máquinas de vetores de suporte. Considerando as seguintes medidas de desempenho: exatidão global e coeficiente de Kappa, o sistema desenvolvido processou 435 imagens RGB, as quais foram obtidas de três cultivos experimentais contendo plantas de cana-de-açúcar, milho e seis espécies de plantas daninhas (Urochloa plantaginea, Urochloa decumbens, Panicum maximum, Euphorbia heterophylla, Ipomoea hederifolia e Ipomoea quamoclit). Os resultados obtidos demonstram que a metodologia possui alto poder para identificar e discriminar plantas daninhas e cultura, alcançando exatidão global e coeficiente Kappa de até 94% e 0,94, respectivamente. Estes resultados suportam a premissa de que um sistema de processamento de imagens é capaz de identificar plantas daninhas na cultura de cana-de-açúcar, estimar o nível de infestação e ainda servir como ferramenta para auxílio à tomada de decisão quanto ao manejo das espécies infestantes / Abstract: The increase in production without causing damage to the environment is one of the biggest challenges of modern agriculture. In the production of sugarcane, this becomes clearer when it comes to the weed management, since the use of herbicides to configure most widely adopted technique. Weeds cause interference in agricultural production, causing reduction in product quality and crop yields. Therefore, the identification of weed species and the level of infestation becomes very important so that appropriate management strategies can be defined. This study sought to develop and evaluate the performance of an image processing system to identify weeds in sugarcane and estimate their level of infestation, since the existence of a computer tool to recognize plants species should give a great support to decision-making about the management of weed communities. The approach taken to identify weeds and crop plants was based on the methodology of bag-of-words. On this methodology, invariant feature points and multiple images are used to create a dictionary of features, the dictionary is then used to ascertain what his words are present the images to be processed, the quantization of the number of words in the dictionary is present in the image made by a probability density function and the mathematical model of rank was made by support vector machine. Considering the performance measures: overall accuracy and Kappa coefficient, the developed system has processed 435 RGB images, what were obtained from three experimental cultives having plants of sugarcane, corn and six weed species (Urochloa plantaginea, Urochloa decumbens, Panicum maximum, Euphorbia heterophylla, Ipomoea hederifolia and Ipomoea quamoclit). The results show that the method has high power to identify and discriminate weed and crop, reaching overall accuracy and Kappa coefficient of up to 94% and 0.94, respectively. These results give support to premise that an image processing system is capable to identify weeds in sugarcane, estimate the infestation level and to be yet a tool for support the decision-making about the management from the weed species / Doutorado / Maquinas Agricolas / Doutor em Engenharia Agrícola

Invasive plants represent an important topic of study in current ecology because of their effects on whole ecosystems. The plants interact with the soil including soil biota, with the other plants in the community and with other organisms, eg. herbivores. Invasive plants often differ from non- invasive plants in nutrient utilization and can thus affect soil pH as well. They may also differ in the way they interact with mycorrhizal fungi that help the plants with nutrient uptake. In this study, the effect of invasive and native plants on soil properties is compared. Congeneric pairs of species, where one species is native and the other invasive, are compared. The native species are chosen so that they are dominant and therefore comparable to the invasive plants in the new environment. The evaluated soil properties are pH value and content of elemental nutrients from abiotic properties, and the amount of mycorrhizal fungi propagules and their spreading rate in soil from the biotic properties. In this study, the invasive and native plants differ only in the content of exchangeable phosphorus and potassium. Content of these two nutrients and one of the indicators of mycorrhizal fungi differ within the pairs of species as well. For most soil properties, the genus of the plant plays the main role, not...

<p> Kudzu (Pueraria montana) is an invasive woody vine widespread throughout the  southeastern United States, with recent studies predicting that its habitat will expand northward.  New occurrences and recent studies using climatic parameters suggest that the Midwestern  region of the United States is at the greatest risk of kudzu invasion. As there have already been  25 reports of kudzu within the Great Lakes basin, and no previous landscape models exist for the  basin, I developed probability models from existing spatial data (land cover, hydrology, geology,  annual precipitation, elevation, aspect, and known kudzu locations) using generalized additive,  bioclimate envelope, and maximum entropy methods. I further expanded each model to include  the basin and a 2.25-degree buffer in order to include 193 reported kudzu sites. For each  predictive model, I determined the area under the curve (AUC) for a receiver operating  characteristic curve (ROC) comparing false positive and false negative rates. I performed field  surveys at eight known sites of kudzu presence in Michigan, Indiana, and Ohio. Each presence  site was paired with a control (known kudzu absence site). I collected environmental data  including canopy cover, volumetric soil moisture, soil pH, litter depth, midstory species diversity  and diameter at breast height (DBH), and overstory basal area. Each environmental measure was  compared between kudzu presence and control survey sites as well as between in-basin and out?of-basin survey sites using a two-way ANOVA. Maximum entropy models produced the highest  AUC in both the basin and buffer models during model development. These models showed that  urban and disturbed habitats resulted in the greatest probability of potential habitat for kudzu. I  found no statistically significant differences in environmental characteristics between kudzu  absent and presence sites or between in- and out-of-basin sites, suggesting kudzu might be  dispersal-limited rather than limited by environmental characteristics. Continuing existing  management and further monitoring of kudzu spread is likely necessary to limit further  introduction and to mitigate spread of kudzu within the Great Lakes region.  </p>

In this study, we extend the spatial weight matrix defined by Getis and Aldstadt (2004) to a more general case. The modified spatial weight matrix performs better than the original spatial weight matrix since the modified spatial weight matrix adjusts weights of observations based on the distance from other observations. Both the simulation study and the application to the ecological process of invasion of non-native invasive plants (NNIPs) provide evidences for the better performance of the modified spatial weight matrix. We also develop procedures that can be used to quantify the invasion stages of NNIPs. The resultant map of invasion stage on county-level provides a useful and meaningful tool for policy makers; especially, it can be used to optimize allocation of management resources. The result of simultaneous autoregressive model shows that not only the biotic and abiotic factors but also human activities play an important role in the establishment and spread of multiflora rose in the Upper Midwest. It also shows the tendency of the establishment and spread of multiflora rose (Rosa Multiflora, Thunb. ex Murr.) in the Upper Midwest.

Indiana University-Purdue University Indianapolis (IUPUI) / Terrestrial carbon sequestration is one of several proposed strategies to reduce the rate of carbon dioxide (CO2) accumulation in the atmosphere, but the impact of plant invasion on soil organic carbon (SOC) storage is unclear. The results of past studies are often confounded by differences in vegetation and environmental conditions. Reed canary grass (Phalaris arundinacea) is an herbaceous species that invades riparian fringes and wetlands throughout North America, including Beanblossom Bottoms – a wetland complex in south-central Indiana. Because of the prolific growth of P. arundinacea, it was hypothesized that significant alterations in SOC pools and dynamics would occur at invaded sites within the wetland complex. To test this hypothesis, study plots were established in areas colonized either by native herbaceous species or by P. arundinacea. Above and below-ground biomass were collected at the middle and end of the growing season and were analyzed for cellulose, lignin, acid detergent fiber, total phenolics, and organic carbon and nitrogen concentration. Soil samples were analyzed for SOC and nitrogen, bulk density, pH, and texture. The biomass of Scirpus cyperinus – a native wetland species was found to contain significantly (P < 0.05) more lignin (168 g kg-1 versus 98 g kg-1) and phenolics (19 g kg-1 versus 3 g kg-1), and had a higher C to N ratio (28 versus 20) than P. arundinacea biomass, suggesting greater recalcitrance of S. cyperinus tissues compared to P. arundinacea biomass. Results of a laboratory incubation study were consistent with the residue biochemistry data and showed that S. cyperinus biomass degraded at much slower rates than the biomass of P. arundinacea. However, measurements of SOC pools (0-30 cm) showed larger pools under P. arundinacea (25.5 Mg C ha-1) than under stands of S. cyperinus (21.8 Mg C ha-1). Likewise, SOC stocks under stands of mixed native vegetation were significantly (P < 0.05) smaller (18.8 Mg C ha-1) than in areas invaded by P. arundinacea. Biomass of the mixed native vegetation was also considered more recalcitrant than that of P. arundinacea based on residue biochemistry. Therefore, contrary to the study hypothesis, residue quality was not a good predictor of SOC stocks in the wetland soils. Thus, it appears that traditional laboratory assessments of biomass recalcitrance and decomposition do not accurately simulate the various biological interactions occurring in the field.