Scaling ozone responses of forest trees to the ecosystem level in a changing climate

Many uncertainties remain regarding how climate change will alter the structure and function of forest ecosystems. At the Aspen FACE experiment in northern Wisconsin, we are attempting to understand how an aspen/birch/maple forest ecosystem responds to long-term exposure to elevated carbon dioxide (CO 2 ) and ozone (O 3 ), alone and in combination, from establishment onward. We examine how O 3 affects the flow of carbon through the ecosystem from the leaf level through to the roots and into the soil micro-organisms in present and future atmospheric CO 2 conditions. We provide evidence of adverse effects of O 3 , with or without co-occurring elevated CO 2 , that cascade through the entire ecosystem impacting complex trophic interactions and food webs on all three species in the study: trembling aspen ( Populus tremuloides Michx . ), paper birch ( Betula papyrifera Marsh), and sugar maple ( Acer saccharum Marsh). Interestingly, the negative effect of O 3 on the growth of sugar maple did not become evident until 3 years into the study. The negative effect of O 3 effect was most noticeable on paper birch trees growing under elevated CO 2 . Our results demonstrate the importance of long-term studies to detect subtle effects of atmospheric change and of the need for studies of interacting stresses whose responses could not be predicted by studies of single factors. In biologically complex forest ecosystems, effects at one scale can be very different from those at another scale. For scaling purposes, then, linking process with canopy level models is essential if O 3 impacts are to be accurately predicted. Finally, we describe how outputs from our long-term multispecies Aspen FACE experiment are being used to develop simple, coupled models to estimate productivity gain/loss from changing O 3 .Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72464/1/j.1365-3040.2005.01362.x.pd

Parâmetros biológicos e tabela de vida de Tetranychus urticae (Acari: Tetranychidae) em cultivares de mamão

Este trabalho foi realizado para avaliar o desenvolvimento e reprodução de Tetranychus urticae em cultivares comerciais de mamão Carica papaya. Foram utilizadas cultivares do grupo "Formosa" ("Tainung 01" e "Calimosa") e do grupo "Solo" ("Golden" e "Sunrise"). Para iniciar o bioensaio, foi transferida uma fêmea fertilizada por disco de folha (n=50 repetições) e retirado após um período de 12h, sendo avaliada a cada 12h, registrando-se o período de incubação, duração do estágio de imaturo, longevidade e fecundidade dos adultos e viabilidade desses estágios. Os resultados indicaram que as cultivares de mamão "Tainung 01", "Calimosa", "Sunrise" e "Golden" são bons hospedeiros para T. urticae. O parâmetro viabilidade não sofreu influência das cultivares em todas as fases de desenvolvimento avaliadas, apresentando valores superiores a 90%. Não houve diferença estatística entre as cultivares nos parâmetros: período de pre-oviposição e viabilidade dos ovos. A cultivar "Tainung 01" apresentou menor potencial hospedeiro, embora houvesse menor duração nos estágios de ovo, larva, protoninfa e ovo-adulto. Nos parâmetros de tabela de vida e fertilidade, apresentou menores valores de Ro, r m e λ e maior valor de Td. Entre as cultivares, o "Sunrise" apresentou um elevado potencial hospedeiro para T. urticae, pois essa cultivar proporcionou a maior produção de ovos por fêmea, maior longevidade das fêmeas, bem como a maior taxa de reprodução (maior Ro, r m e λ e menor valor de Td).The study was conducted to evaluate the Tetranichus urticae development and reproduction in commercial Carica papaya cultivars. The assayed cultivars belongs to the "Formosa" ("Tainung 01" and "Calimosa") and from the "Solo" ("Golden" and "Sunrise") groups. A fertilized female was transferred to a leaf dish (n=50 repetitions) and was removed after a period of 12 hours and evaluations were done every 12 hours recording the incubation period, length of immature stage, longevity and fecundity of adults and viability of these stages. The cultivars of papaya, "Tainung 01", "Calimosa", "Sunrise" and "Golden" are adequate hosts for T. urticae. The recorded viability above 90% was not influenced by the different cultivars during all the development phases. There was not statistic difference among the cultivars in the parameters: pre-ovopositional period, and egg viability. Mites assayed in "Tainung 01" cultivar showed a shorter duration of the egg, larva, protonymph and egg-adult. At life table parameters and fertility, presented smaller Ro, r m and λ, and larger Td. "Sunrise" is the cultivar most adequate for T. urticae development, considering that mites assayed in this cultivar showed a larger production of eggs per female, longer female longevity, and higher reproduction rate (larger Ro, r m and λ and smaller Td)

Aphid-plant interactions at ambient and elevated CO_2

SIGLEAvailable from British Library Document Supply Centre-DSC:DX200694 / BLDSC - British Library Document Supply CentreGBUnited Kingdo