Abstracts on Global Climate Change

Apr 2007

Causes of lineage decline in the Aplodontidae: Testing for the influence of physical and biological change

Hopkins, SSB


This study documents diversity decline in a once-speciose rodent clade, the family Aplodontidae, and evaluates the potential influence of three commonly suggested controls on diversity: climate change, floral change, and competitive interactions. Aplodontids first appeared in the late Eocene, diversified during the early Oligocene, declined precipitously at the end of the Oligocene such that standing diversity was only about 5 species during the early Miocene, peaked again in the early middle Miocene, then declined through the late Miocene, and are entirely absent from the Pliocene and early Pleistocene fossil record. This long term pattern culminated in the survival of a single extant species, Aplodontia rufa, the mountain beaver. The species’ richness and body size distribution through time were compared with the timing of climatic changes as inferred from global oxygen isotope curves, with the rise of grasslands as inferred from phytolith and other stable isotope studies, and with fluctuating diversity of potential competitors as inferred from published stratigraphic and geographic distributions. The timing of global climate change is decoupled from the diversity fluctuations and seems not to have been a proximate cause. Rise of grasslands and the increasing dominance Of C-4 vegetation correlates with diversity decline in the late Oligocene and late Miocene, but data are sparse, and more work will be required to determine the mechanism driving this relationship. Examination of potential mammalian competitors (sciurids and castorids) finds no evidence for competitive replacement of aplodontids. It is difficult to ascribe the fluctuations in aplodontid diversity to a single cause. The explanation likely involves vegetation changes associated with the spread of grasslands, but there is some variation in diversity that cannot be explained by the vegetation, at least using the proxies employed here. Climate and competition are less consistent with the available data. The reasons for the decline of aplodontids in the late Oligocene and the late Miocene apparently involved the interaction of multiple physical and biological causes, coupled with the chance events that underlie any evolutionary process. (c) 2006 Elsevier B.V. All rights reserved.

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Environmental hazard analysis and effective remediation of highway seepage

Yuan, RM Yang, YS Qiu, X Ma, FS


Risk assessment and minimisation of environmental hazards are critical issues to consider in the geotechnical engineering projects. A case of highway pavement seepage induced by groundwater, at a locality along the section of Hua-Qing Highway of Guangdong Province, China, is presented for environmental hazard analysis and effective remediation. The environmental hazard analyses were based on in situ hydrogeologic investigation, rock-soil testing and integrated environmental understanding. The analyses indicate that the highway seepage was caused by elevation of groundwater hydraulic pressure in low permeable strata near the highway pavement, which was controlled by landform, hydrology, weather and road structure. The risk source of groundwater ‘flooding’ was the groundwater and surface water in the ring-like valley around Fenshui Village. A blind-ditch system for effective remediation of the pavement seepage hazard was proposed and successfully implemented by declining groundwater table near the highway based on the comprehensive assessment of various conditions. This geotechnical accident shows that the role of groundwater is an essential factor to consider in the geotechnical and environmental engineering studies and multidisciplinary effort for risk assessment of environmental hazards is important under current global climate change condition. (c) 2006 Elsevier B.V. All rights reserved.

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Long-term changes in the geographic distribution and population structures of Osilinus lineatus (Gastropoda : Trochidae) in Britain and Ireland

Mieszkowska, N Hawkins, SJ Burrows, MT Kendall, MA


Since the rate of global climate change began to accelerate in the 1980s, the coastal seas of Britain have warmed by tip to l degrees C. Locations close to the northern range edges of a southern trochid gastropod Osilinus lineatus in Britain previously surveyed in the 1950s and 1980s were resurveyed during 2002-2004 to determine whether changes in the success of near-limit populations had occurred during the period of climate warming. Between the 1980s and the 2000s, the range limits had extended by up to 55 krn. Populations sampled over a latitudinal extent of 4 degrees from northern limits towards the centre of the range showed synchronous increases in abundance throughout the years sampled, suggesting a large-scale factor such as climate was driving the observed changes. These increases in abundance and changes in range limits are likely to have occurred via increased recruitment success in recent years.

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Construction of a novel economy-climate model

Chou, JM Dong, WJ Ye, DZ


An attempt has been made to construct a novel economy-climate model by combining climate change research with agricultural economy research to evaluate the influence of global climate change on grain yields. The insertion of a climate change factor into the economic C-D (Cobb-Dauglas) production function model yields a novel evaluation model, which connects the climate change factor to the economic variation factor, and the performance and reasonableness of the novel evaluation model are also preliminarily simulated and verified.

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Evolutionary aspects of climate-induced changes and the need for multidisciplinarity

Pertoldi, C Bach, LA


An integrated view on the possible effects of global climate change is provided while taking into account that not only the rising average temperature is likely to impact natural populations but also that increased variation around the mean and higher frequency of extreme events will be important. We propose that complex genetic effects in concert with demographic patterns may affect how focal populations react to the environmental challenge in an adaptive way (if they can). In order to aim for an inclusive picture of the ongoing environmental change we argue for a synthesis of knowledge from a range of ‘classical’ disciplines such as quantitative genetics, conservation genetics and population ecology. A hereto little exposed concern is the importance of the increase in amplitude of environmental fluctuations and how the corresponding evolutionary and ecological reactions are expected to occur. Due to the complex interactions between the ecological and genetic mechanisms in the response to climate-induced impacts interdisciplinary approaches are the most promising path in seeking knowledge about the present and future changes in the biosphere. (c) 2007 Elsevier Ltd. All rights reserved.

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Irrigation and enhanced soil carbon input effects on below-ground carbon cycling in semiarid temperate grasslands

Xiao, CW Janssens, IA Liu, P Zhou, ZY Sun, OJ

NEW PHYTOLOGIST 174:4 835-846

Global climate change is generally expected to increase net primary production, resulting in increased soil carbon (C) inputs. To gain an understanding of how such increased soil C inputs would affect C cycling in the vast grasslands of northern China, we conducted a field experiment in which the responses of plant and microbial biomass and respiration were studied. Our experiment included the below-ground addition of particulate organic matter (POM) at rates equivalent to 0, 60, 120 and 240 g C m(-2), under either natural precipitation or under enhanced precipitation during the summer period (as predicted for that region in recent simulations using general circulation models). We observed that addition of POM had a large effect on soil microbial biomass and activity and that a major part of the added C was rapidly lost from the system. This suggests that microbial activity in the vast temperate grassland ecosystems of northern China is energy-limited. Moreover, POM addition (and the associated nutrient release) affected plant growth much more than the additional water input. Although we performed no direct fertilization experiments, the response of plant productivity to POM addition (and associated release of nutrients) leads us to believe that plant productivity in the semiarid grassland ecosystems of northern China is primarily limited by nutrients and not by water.

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Population trends and spatial synchrony in peripheral populations of the endangered Lesser grey shrike in response to environmental change

Giralt, D Valera, F


Regional synchronization in species dynamics as well as particular ecological and demographic characteristics of peripheral populations poses special challenges for conservation purposes, particularly under the current scenario of global climate change. Here, we study the population trend and spatial synchrony of several peripheral populations of the endangered Lesser grey shrike Lanius minor at the western limit of its breeding range (southern France and northeast Spain). In an attempt to ascertain the effect of environmental change on the decline of the species we also look for evidence of climate changes in the breeding and wintering area of this shrike and related effects on vegetation by using the normalized difference vegetation index (NDVI). We found that the interannual fluctuations of the peripheral populations in France and Spain are strongly correlated, therefore suggesting that their decline can be under the influence of a common factor. We obtained clear evidence of climatic change (an increased thermal oscillation) in one peripheral population that could have resulted in a decrease of the NDVI index in the area. Our study finds correlational evidence that climatic variables in the breeding area may account for fluctuations in abundances of some populations and that environmental conditions experimented by some population could influence the fate of the neighboring populations. Our results indicate that the studied peripheral populations are spatially synchronized, so that conservation efforts should be applied at a large-scale encompassing all the isolated populations at the western border of the range of the species in the Mediterranean area.

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Combining airborne photographs and spaceborne SAR data to monitor temperate glaciers: Potentials and limits

Trouye, E Vasile, G Gay, M Bombrun, L Grussenmeyer, P Landes, T Nicolas, JM Bolon, P Petillot, I Julea, A Valet, L Chanussot, J Koehl, M


Monitoring temperate glacier activity has become more and more necessary for economical and security reasons and as an indicator of the local effects of global climate change. Remote sensing data provide useful information on such complex geophysical objects, but they require specific processing techniques to cope with the difficult context of moving and changing features in high-relief areas. This paper presents the first results of a project involving four laboratories developing and combining specific methods to extract information from optical and synthetic aperture radar (SAR) data. Two different information sources are processed, namely: 1) airborne photography and 2) spaceborne C-band SAR interferometry. The difficulties and limitations of their processing in the context of Alpine glaciers are discussed and illustrated on two glaciers located in the Mont-Blanc area. The results obtained by aerial triangulation techniques provide digital terrain models with an accuracy that is better than 30 cm, which is compatible with the computation of volume balance and useful for precise georeferencing and slope measurement updating. The results obtained by SAR differential interferometry using European Remote Sensing Satellite images show that it is possible to measure temperate glacier surface velocity fields from October to April in one-day interferograms with approximately 20-m ground sampling. This allows to derive ice surface strain rate fields required to model the glacier flow. These different measurements are complementary to results obtained during the summer from satellite optical data and ground measurements that are available only in few accessible points.

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The agricultural impact of global climate change: How can developing-country farmers cope?

Russell, N

GEOTIMES 52:4 30-34

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Ecophysiological response and morphological adjustment of two Central Asian desert shrubs towards variation in summer precipitation

Xu, H Li, Y Xu, GQ Zou, T


As part of global climate change, variation in precipitation in arid ecosystems is leading to plant adaptation in water-use strategies; significant interspecific differences in response will change the plant composition of desert communities. This integrated study on the ecophysiological and individual morphological scale investigated the response, acclimation and adaptation of two desert shrubs, with different water-use strategies, to variations in water conditions. The experiments were carried out on two native dominant desert shrubs, Tamarix ramosissima and Haloxylon ammodendron, under three precipitation treatments (natural, double and no precipitation, respectively), in their original habitats on the southern periphery of Gurbantonggut Desert, Central Asia, during the growing season in 2005. Changes in photosynthesis, transpiration, leaf water potential, water-use efficiency, above-ground biomass accumulation and root distribution of the two species were examined and compared under the contrasting precipitation treatments. There were significant interspecific differences in water-use strategy and maintenance of photosynthesis under variation in precipitation. For the phreatophyte T. ramosissima, physiological activity and biomass accumulation rely on the stable groundwater, which shields it from fluctuation in the water status of the upper soil layers caused by precipitation. For the non-phreatophyte H. ammodendron, efficient morphological adjustment, combined with strong stomatal control, contributes to its acclimation to variation in precipitation. On account of its positive responses to increased precipitation, H. ammodendron is predicted to succeed in interspecific competition in a future, moister habitat.

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Tension wood formed in Fagus sylvatica and Alnus glutinosa after simulated mass movement events

Heinrich, I Gartner, H Monbaron, M

IAWA JOURNAL 28:1 39-48

Due to the likelihood of global climate change, the frequency and magnitude of natural hazards such as mass movements may likewise change, thus favouring the refinement of methods to detect and quantify geomorphic events when precise records are not available. Geomorphic events typically have a significant effect on tree growth, e.g., reaction wood marked by changes in ring widths and wood density. To date, several dendroecological techniques have been developed to document the occurrence of these events but it rarely has been possible to retrieve additional information from reaction wood concerning the precise kind and intensity of geomorphic events. Additional qualitative information inferred from reaction wood of trees holds the potential to not only document but also estimate important characteristics of natural hazard events. To refine the methods already used in dendrogeornorpology, experiments simulating various geomorphic events were used to monitor subsequent wood anatomical responses of Fagus sylvatica and Alnus glutinosa. The preliminary results indicate that these two common broadleaf tree species show variations in their reactions to different experimental treatments.

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Breeding distributions of north American bird species moving north as a result of climate change

Hitch, AT Leberg, PL


Geographic changes in species distributions toward traditionally cooler climes is one hypothesized indicator of recent global climate change. We examined distribution data on 56 bird species. If global warming is affecting species distributions across the temperate northern hemisphere, these data should show the same northward range expansions of birds that have been reported for Great Britain. Because a northward shift of distributions might be due to multidirectional range expansions for multiple species, we also examined the possibility that birds with northern distributions may be expanding their ranges southward. There was no southward expansion of birds with a northern distribution, indicating that there is no evidence of overall range expansion of insectivorous and granivorous birds in North America. As predicted, the northern limit of birds with a southern distribution showed a significant shift northward (2.35 km/year). This northward shift is similar to that observed in previous work conducted in Great Britain: the widespread nature of this shift in species distributions over two distinct geographical regions and its coincidence with a period of global warming suggests a connection with global climate change.

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What environmental fate processes have the strongest influence on a completely persistent organic chemical’s accumulation in the Arctic?

Meyer, T Wania, F


Fate and transport models can be used to identify and classify chemicals that have the potential to undergo long-range transport and to accumulate in remote environments. For example, the Arctic contamination potential (ACP), calculated with the help of the zonally averaged global transport model Globo-POP, is a numerical indicator of an organic chemical’s potential to be transported to polar latitudes and to accumulate in the Arctic ecosystem. It is important to evaluate how robust such model predictions are and in particular to appreciate to what extent they may depend on a specific choice of environmental model input parameters. Here, we employ a recently developed graphical method based on partitioning maps to comprehensively explore the sensitivity of ACP estimates to variations in environmental parameters. Specifically, the changes in the ACP of persistent organic contaminants to changes in each environmental input parameter are plotted as a function of the two-dimensional hypothetical “chemical space” defined by two of the three equilibrium partition coefficients between air, water and octanol. Based on the patterns obtained, this chemical space is then segmented into areas of similar parameter sensitivities and superimposed with areas of high default ACP and elevated environmental bioaccumulation potential within the Arctic. Sea ice cover, latitudinal temperature gradient, and macro-diffusive atmospheric transport coefficients, and to a lesser extent precipitation rate, display the largest influence on ACP-values for persistent organic contaminants, including those that may bioaccumulate within the polar marine ecosystems. These environmental characteristics are expected to be significantly impacted by global climate change processes, highlighting the need to explore more explicitly how climate change may affect the long-range transport and accumulation behavior of persistent organic pollutants. (C) 2006 Elsevier Ltd. All rights reserved.

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Influence of elevated CO2 concentrations on thermal tolerance of the edible crab Cancer pagurus

Metzger, R Sartoris, FJ Langenbuch, M Portner, HO


Current trends of global climate change affect marine ectothermal animals not only through the increase in ambient temperature. Synergistic effects of carbon dioxide and temperature changes as well as more frequent hypoxia events must also be considered. As a first attempt, the combined effects of warming and elevated CO2 concentrations were investigated in the edible crab (Cancer pagurivs). Arterial oxygen tension (PaO2) in the haemolymph was recorded on-line during a progressive warming scenario from 10 to 22 degrees C and cooling back to 10 degrees C. Hypercapnia (1% CO2) caused a significant reduction of oxygen partial pressure in the haemolymph as well as a large, 5 degrees C downward shift of upper thermal limits of aerobic scope. The present findings are the first to show that hypercapnia causes enhanced sensitivity to heat and thus, a narrowing of the thermal tolerance window of a marine ectotherm. Such interactions of ambient temperature and anthropogenic increases in ambient CO2 concentrations will need to be considered during future investigations of the effects of climate change on ecosystems. (c) 2007 Elsevier Ltd. All rights reserved.

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