Dynamic and complex microclimate responses to warming and grazing manipulations

Synthesis efforts that identify patterns of ecosystem response to a suite of warming manipulations can make important contributions to climate change science. However, cross-study comparisons are impeded by the paucity of detailed analyses of how passive warming and other manipulations affect microclimate. Here we document the independent and combined effects of a common passive warming manipulation, open-top chambers (OTCs), and a simulated widespread land use, clipping, on microclimate on the Tibetan Plateau. OTCs consistently elevated growing season averaged mean daily air temperature by 1.0-2.0 degrees C, maximum daily air temperature by 2.1-7.3 degrees C and the diurnal air temperature range by 1.9-6.5 degrees C, with mixed effects on minimum daily air temperature, and mean daily soil temperature and moisture. These OTC effects on microclimate differ from reported effects of a common active warming method, infrared heating, which has more consistent effects on soil than on air temperature. There were significant interannual and intragrowing season differences in OTC effects on microclimate. For example, while OTCs had mixed effects on growing season averaged soil temperatures, OTCs consistently elevated soil temperature by approximately 1.0 degrees C early in the growing season. Nonadditive interactions between OTCs and clipping were also present: OTCs in clipped plots generally elevated air and soil temperatures more than OTCs in nonclipped plots. Moreover, site factors dynamically interacted with microclimate and with the efficacy of the OTC manipulations.These findings highlight the need to understand differential microclimate effects between warming methods, within warming method across ecosystem sites, within warming method crossed with other treatments, and within sites over various timescales. Methods, sites and scales are potential explanatory variables and covariables in climate warming experiments. Consideration of this variability among and between experimental warming studies will lead to greater understanding and better prediction of ecosystem response to anthropogenic climate warming.

Local warming about 1.3 degrees C in alpine meadow has no effect on root vole (Microtus oeconomus L.) population during winter

The influence of air and soil warming on root vole (Microtus oeconomus L.) population was studied in winter period in top open chambers (OTC) (0.8-1.8 m(2) warmed by conical fiberglass material and situated in alpine meadow (3250 m) at Qinghai-Tibet Plateau, China. The OTCs were distributed on an area of 30 x 30 m of experimental warming site; another site of the same area was a control one. The root vole population was investigated on two pairs of sites in "low-grazing" and "high-grazing" (by sheep) parts of the meadow; mark-recapture method was used. The winter-season averaged air and soil temperature inside of the chambers were 1.3 degrees C higher than the temperature outside the chambers. The warming in the chambers had no statistically significant effect on root vole numbers, on average body mass of individual, and on average body mass of males and females. In conclusion, as small as 1.3 degrees C warming of soil and air introduced locally and on small (several m(2)) scale, in the alpine meadow habitat in winter period, has possibly no effect on root vole numbers and biomass.

Experimental warming causes large and rapid species loss, dampened by simulated grazing, on the Tibetan Plateau

We investigated the independent and combined effects of experimental warming and grazing on plant species diversity on the north-eastern Tibetan Plateau, a region highly vulnerable to ongoing climate and land use changes. Experimental warming caused a 26-36% decrease in species richness, a response that was generally dampened by experimental grazing. Higher species losses occurred at the drier sites where N was less available. Moreover, we observed an indirect effect of climate change on species richness as mediated by plant-plant interactions. Heat stress and warming-induced litter accumulation are potential explanations for the species' responses to experimental warming. This is the first reported experimental evidence that climate warming could cause dramatic declines in plant species diversity in high elevation ecosystems over short time frames and supports model predictions of species losses with anthropogenic climate change.

Avaliacao preliminar de cinco tipos de graviola (Annona muricata L.) nas condicoes de Manaus-AM.

Foram avaliados, na colecao de fruteiras da Embrapa Amazonia Ocidental, cinco tipos de graviola (Morada, FAO II, Blanca, Lisa e B), com o objetivo de se verificar o desenvolvimento vegetativo, producao e caracteristicas do fruto. O plantio foi realizado em linha com dez plantas de cada tipo de graviola, em espacamento de 4m entre plantas e 8m entre linhas. As caracteristicas avaliadas foram: diametro do caule, diametro da copa, numero de frutos/planta, peso do fruto, peso da polpa, numero de sementes/fruto, peso das sementes, teor de solidos soluveis totais (°Brix) e periodo de frutificacao. No terceiro ano de plantio, Morada produziu, em media, 18 frutos/planta, com peso media de 2,82kg, e FAO II, 16 frutos/planta, com peso medio de 2,90kg, com producao estimada de 7,8t/ha e 7,2t/ha de frutos, respectivamente. Lisa apresentou a menor media de frutos/planta (duas unidades). Esses resultados indicam a viabilidade do cultivo de FAO II e Morada para as condicoes de Manaus.

A cultura da gravioleira (Annona muricata L.).

Informacoes sobre o cultivo da graviola envolvendo: clima, solo, descricao botanica, variedades, propagacao, procedimentos para obtencao de mudas, preparo da area e plantio definitivo, tratos culturais (poda, capina, adubacao, doencas, pragas), floracao, frutificacao, producao, colheita, comercializacao, coeficiente tecnico, em Manaus-AM (Brasil).

O cultivo da pinha, fruta-do-conde ou ata (Annona squamosa, L.) no Brasil.

A Pinha, Fruta-do-conde ou Ata (Annona squamosa, L.) pertence a familia das anonaceas. No Brasil, e considerada uma fruta exotica cuja producao vem aumentando nos ultimos anos. Atualmente, os maiores produtores da pinha sao os Estados de Alagoas e de Sao Paulo. Essa anonacea apresenta frutos de sabor muito agradavel e ricos em minerais e vitaminas, sendo portanto, um bom complemento alimentar na dieta humana. Alem disso, tem sido isolados compostos quimicos presentes em diferentes partes da planta, como acetogeninas e alcaloides que apresentam atividades inseticidas e medicinais. Este trabalho apresenta uma revisao dos principais topicos para uma producao eficiente da pinha em diferentes estados brasileiros.

What we need to know before speaking on Climate Change and Global Warming

Workshop on Energy Greenhouse Gases & Environment, Porto, 2008

The toxicology of climate change: environmental contaminants in a warming world.

Climate change induced by anthropogenic warming of the earth's atmosphere is a daunting problem. This review examines one of the consequences of climate change that has only recently attracted attention: namely, the effects of climate change on the environmental distribution and toxicity of chemical pollutants. A review was undertaken of the scientific literature (original research articles, reviews, government and intergovernmental reports) focusing on the interactions of toxicants with the environmental parameters, temperature, precipitation, and salinity, as altered by climate change. Three broad classes of chemical toxicants of global significance were the focus: air pollutants, persistent organic pollutants (POPs), including some organochlorine pesticides, and other classes of pesticides. Generally, increases in temperature will enhance the toxicity of contaminants and increase concentrations of tropospheric ozone regionally, but will also likely increase rates of chemical degradation. While further research is needed, climate change coupled with air pollutant exposures may have potentially serious adverse consequences for human health in urban and polluted regions. Climate change producing alterations in: food webs, lipid dynamics, ice and snow melt, and organic carbon cycling could result in increased POP levels in water, soil, and biota. There is also compelling evidence that increasing temperatures could be deleterious to pollutant-exposed wildlife. For example, elevated water temperatures may alter the biotransformation of contaminants to more bioactive metabolites and impair homeostasis. The complex interactions between climate change and pollutants may be particularly problematic for species living at the edge of their physiological tolerance range where acclimation capacity may be limited. In addition to temperature increases, regional precipitation patterns are projected to be altered with climate change. Regions subject to decreases in precipitation may experience enhanced volatilization of POPs and pesticides to the atmosphere. Reduced precipitation will also increase air pollution in urbanized regions resulting in negative health effects, which may be exacerbated by temperature increases. Regions subject to increased precipitation will have lower levels of air pollution, but will likely experience enhanced surface deposition of airborne POPs and increased run-off of pesticides. Moreover, increases in the intensity and frequency of storm events linked to climate change could lead to more severe episodes of chemical contamination of water bodies and surrounding watersheds. Changes in salinity may affect aquatic organisms as an independent stressor as well as by altering the bioavailability and in some instances increasing the toxicity of chemicals. A paramount issue will be to identify species and populations especially vulnerable to climate-pollutant interactions, in the context of the many other physical, chemical, and biological stressors that will be altered with climate change. Moreover, it will be important to predict tipping points that might trigger or accelerate synergistic interactions between climate change and contaminant exposures.

Comparing the model-simulated global warming signal to observations using empirical estimates of unforced noise.

The comparison of observed global mean surface air temperature (GMT) change to the mean change simulated by climate models has received much public and scientific attention. For a given global warming signal produced by a climate model ensemble, there exists an envelope of GMT values representing the range of possible unforced states of the climate system (the Envelope of Unforced Noise; EUN). Typically, the EUN is derived from climate models themselves, but climate models might not accurately simulate the correct characteristics of unforced GMT variability. Here, we simulate a new, empirical, EUN that is based on instrumental and reconstructed surface temperature records. We compare the forced GMT signal produced by climate models to observations while noting the range of GMT values provided by the empirical EUN. We find that the empirical EUN is wide enough so that the interdecadal variability in the rate of global warming over the 20(th) century does not necessarily require corresponding variability in the rate-of-increase of the forced signal. The empirical EUN also indicates that the reduced GMT warming over the past decade or so is still consistent with a middle emission scenario's forced signal, but is likely inconsistent with the steepest emission scenario's forced signal.

Unanticipated biological changes and global warming

Evidence of global warming is now unequivocal, and studies suggest that it has started to influence natural systems of the planet, including the oceans. However, in the marine environment, it is well-known that species and ecosystems can also be influenced by natural sources of large-scale hydro-climatological variability. The North Atlantic Oscillation (NAO) was negatively correlated with the mean abundance of one of the subarctic key species Calanus finmarchicus in the North Sea. This correlation was thought to have broken down in 1996, however, the timing has never been tested statistically. The present study revisits this unanticipated change and reveals that the correlation did not break down in 1996 as originally proposed but earlier, at the time of an abrupt ecosystem shift in the North Sea in the 1980s. Furthermore, the analyses demonstrate that the correlation between the NAO and C. finmarchicus abundance is modulated by the thermal regime of the North Sea, which in turn covaries positively with global temperature anomalies. This study thereby provides evidence that global climate change is likely to alter some empirical relationships found in the past between species abundance or the ecosystem state and large-scale natural sources of hydro-climatological variability. A theory is proposed to explain how this might happen. These unanticipated changes, also called ‘surprises’ in climatic research, are a direct consequence of the complexity of both climatic and biological systems. In this period of rapid climate change, it is therefore hazardous to integrate meteo-oceanic indices such as the NAO in models used in the management of living resources, as it has been sometimes attempted in the past.

Trophic amplification of climate warming

Ecosystems can alternate suddenly between contrasting persistent states due to internal processes or external drivers. It is important to understand the mechanisms by which these shifts occur, especially in exploited ecosystems. There have been several abrupt marine ecosystem shifts attributed either to fishing, recent climate change or a combination of these two drivers. We show that temperature has been an important driver of the trophodynamics of the North Sea, a heavily fished marine ecosystem, for nearly 50 years and that a recent pronounced change in temperature established a new ecosystem dynamic regime through a series of internal mechanisms. Using an end-to-end ecosystem approach that included primary producers, primary, secondary and tertiary consumers, and detritivores, we found that temperature modified the relationships among species through nonlinearities in the ecosystem involving ecological thresholds and trophic amplifications. Trophic amplification provides an alternative mechanism to positive feedback to drive an ecosystem towards a new dynamic regime, which in this case favours jellyfish in the plankton and decapods and detritivores in the benthos. Although overfishing is often held responsible for marine ecosystem degeneration, temperature can clearly bring about similar effects. Our results are relevant to ecosystem-based fisheries management (EBFM), seen as the way forward to manage exploited marine ecosystems.