Abstracts on Global Climate Change

Oct 2006

Farmers’ annual activities are not tracking the speed of climate change

Menzel, A Von Vopelius, J Estrella, N Schleip, C Dose, V


Global climate change impacts are already tracked in many physical and biological systems and they reveal a consistent picture of changes, e.g. an earlier onset of spring events in mid and higher latitudes and a lengthening of the plant growing season. However, available results are mainly based on the study of wild plants, whereas only a few studies have hinted at an earlier spring onset for agricultural plants. So far, no comprehensive study has compared phenological shifts between agricultural crops, fruit trees and wild plants. We analysed phenological time series of 93 phases in Germany (1951-2004) employing Bayesian nonparametric function estimation, and found that events related to the production of annual crops clearly differ from spring and summer events in wild plants and fruit trees. While non-farmer driven agricultural events and spring and summer growth stages of wild plants and fruit trees advanced (i.e. occurred earlier) by 4.4 to 7.1 d decade(-1), farming indicators, such as sowing and subsequent emergence of spring and winter crops, as well as harvesting, advanced by only 2.1 d decade(-1). The estimated functional behaviour and emergence of discontinuous changes are clearly different between the 2 groups. We conclude that phenological responses to temperature changes are only reflected in data of wild plants, fruit trees and those spring growth stages of winter crops and later growth stages of spring crops which are exclusively triggered by climate, while other changes due to agricultural production are subject to management practice alterations.

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Determination of forest growth trends in Komi Republic (northwestern Russia): combination of tree-ring analysis and remote sensing data

Lopatin, E Kolstrom, T Spiecker, H


It is very important to detect changes in forest productivity due to the global change on a large scale. In this work, the evolution of the vegetation in the Komi Republic (northwestern Russia) from 1982 to 2001 was analyzed using NOAA AVHRR PAL time series. A statistically significant correlation (adjusted r(2) = 0.44-0.59) between Normalized Difference Vegetation Index (NDVI) data and tree ring width (261 living trees) was identified for the territory of the Komi Republic. The increased site productivity reflected an increase of integrated NDVI values from June to August. This allows NDVI to be used as a proxy for estimation of forest growth trends for the recent decades. A positive and significant trend in NDVI data was identified from 1982 to 2001, coinciding with an increase in site productivity in the study area. The decrease in precipitations coincided with an increase in site productivity (highest r(2) was 0.71). The increase in productivity reflected in NDVI data is maximal on the sites with increased temperature and decreased precipitations. In the Komi Republic the distribution of the trends in NDVI data changes on the south-west to north-east gradient. NDVI data could be used to increase spatial resolution of tree ring width series. Taking into account the relatively small role of human activity in the Komi Republic compared with Europe, the site productivity during recent decades also increased in relatively untouched forests.

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Predicted climate change alters the indirect effect of predators on an ecosystem process

Lensing, JR Wise, DH


Changes in rainfall predicted to occur with global climate change will likely alter rates of leaf-litter decomposition through direct effects on primary decomposers. In a field experiment replicated at two sites, we show that altered rainfall may also change how cascading trophic interactions initiated by arthropod predators in the leaf litter indirectly influence litter decomposition. On the drier site there was no interaction between rainfall and the indirect effect of predators on decomposition. In contrast, on the moister site spiders accelerated the disappearance rate of deciduous leaf litter under low rainfall, but had no, or possibly a negative, indirect effect under high rainfall. Thus, changes resulting from the more intense hydrological cycle expected to occur with climate change will likely influence how predators indirectly affect an essential ecosystem process.

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Relationship between climate, pollen concentrations of Ambrosia and medical consultations for allergic rhinitis in Montreal, 1994-2002

Breton, MC Garneau, M Fortier, I Guay, F Louis, J


The aim of this study is to evaluate the influence of meteorological factors on Ambrosia pollen concentrations and its impact on medical consultations for allergic rhinitis of residents from various socio-economic levels in Montreal (Quebec, Canada) between 1994 and 2002. The study was conducted to recognize the sensitivity of pollen productivity to daily climate variability in order to estimate the consequences on human health vulnerability in the context of global climate change. Information related to medical consultations for allergic rhinitis due to pollen comes from the Quebec Health Insurance Board (Regie de l’assurance-maladie du Quebec). Ambrosia pollen concentration was measured by the Aerobiology Research Laboratories (Nepean, Ontario). Daily temperature (maximum, minimum, and mean) and precipitation data were obtained from the Meteorological Service of Canada. Socio-economic data come from the 1996 and 2001 census data of Statistics Canada. Between 1994 and 2002, during the Ambrosia pollen season, 7667 consultations for allergic rhinitis due to pollen were recorded. We found a significant association between the number of medical consultations and pollen levels. Significant associations were detected for over-consultation the day of exposure, 1, 2, 3 and 5 days after exposure to high levels of pollen. The consultation rate is higher from low-income residents (3.10 consultations per 10,000 inhabitants) than for high-income (1.65 consultations per 10,000 inhabitants). Considering the demonstrated impact of pollen levels on health, it has become critical to ensure adequate monitoring of Ambrosia and its meteorological sensivity in the context of the anticipated climate change and its potential consequences on human health. (c) 2006 Elsevier B.V. All rights reserved.

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Aquatic plants diversity in arid zones of Northwest China: patterns, threats and conservation

Li, ZQ Yu, D Xiong, W Wang, D


We investigated aquatic plant diversity by conducting the field investigation and collecting the published data in the arid regions of Northwest China. Two hundred and twenty four taxa of vascular aquatic plants representing 64 genera and 34 families occur in this area, 8.48% of which are endemic. Among these, 1 genus and 6 species were new state records and 1 family, 9 genera and 29 species were new area records. Typhaceae, Potamogetonaceae, Juncaginaceae and Haloragaceae were the most frequent families (considering relative frequency of occurrence), whereas Cyperaceae, Potamogetonaceae and Ranuncnlaceae are the most species-rich. The most frequent genera were Typha, Potamogeton, and Triglochin, and the most species-rich were Potamogeton, Eleocharis and Scirpus. The most frequent species are Triglochin palustre, Myriophyllum spicatum, Potamogeton pectinatus and Typha angustifolia. Aquatic plants diversity is distributed unevenly in the region. The maximum species occurs in Dzungarian basin while the least species in Hexi corridor. The aquatic flora in arid zone of China is not distinctive although some endemic species are found, most species are widely distributed. Local aquatic plants diversity can be influenced by many factors such as hydrological alteration, habitat loss, over-grazing, high human population pressure, global climate change, an inappropriate economic development policy. Among them, the largest threat to aquatic plants biodiversity may be habitat loss due to hydrological alteration. In order to conserve the aquatic plants biological resources and biodiversity in this region, some strategies and measures must be suggested including strengthening scientific research and biodiversity education in the local people, balancing economic development and ecological conservation, and enhancing governmental assistance and subsidy to the local residents.

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Ecological niche modelling and prioritizing areas for species reintroductions

Martinez-Meyer, E Peterson, AT Servin, JI Kiff, LF

ORYX 40:4 411-418

Species reintroduction programmes, in prioritizing areas for reintroductions, have traditionally used tools that include measures of habitat suitability and evaluations of area requirements for viable populations. Here we add two tools to this approach: evaluation of ecological requirements of species and evaluation of future suitability for species facing changing climates. We demonstrate this approach with two species for which reintroduction programmes are in the planning stages in Mexico: California condor Gymnogyps californianns and Mexican wolf Canis lupus baileyi. For the condor, we identify three areas clustered in the Sierra San Pedro Martir, Baja California; for the wolf, we identify a string of suitable sites along the Sierra Madre Occidental of western Mexico. We discuss the limitations of this approach, identifying ways in which the models illustrated could be made more realistic and directly useful to reintroduction programmes.

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Soil carbon turnover in the McMurdo Dry Valleys, Antarctica

Barrett, JE Virginia, RA Parsons, AN Wall, DH


Terrestrial ecosystems of the Antarctic Dry Valleys are among the most inhospitable soil environments on Earth due to climate and substrate limitations over biota. These ecosystems present a challenge to understanding controls over carbon (C) cycling because likely sources of organic matter are 10(2)-10(4) yrs old and in situ soil respiration is typically less than 1.0 mu mol CO2 m(-2) s(-1). In this paper we describe an analytical approach to characterize kinetic pools of labile and recalcitrant soil C, and estimate C turnover in dry valley soils based upon these descriptions. Rate parameters for C turnover were derived from laboratory incubations conducted under a range of soil moistures and temperatures. We developed a C flux and reservoir model using these rate parameters along with published estimates of internal C transformations in soil microbial ecosystems, and a previously described primary production (NPP) model for Antarctic endolithic communities. We found that decomposition in 120 d incubations was well described by double-exponential rate kinetics, and that temperature, moisture and substrate availability significantly influenced observed rates of soil respiration. Simulations of soil C cycling based upon these parameters produced initially high rates of soil respiration following inputs of external organic matter, with mean residence times for C of 10-60 yrs. Soil organic C content equilibrated at 44-140% of observed levels within 1000 yrs. Simulations of equilibrium C were sensitive to NPP, microbial efficiency (Y), and the distribution of C inputs into labile and passive pools, indicating that more thorough investigation of microbial influence over the C cycle in dry valley soils is necessary. (c) 2006 Elsevier Ltd. All rights reserved.

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Lichen flora around the Korean Antarctic Scientific Station, King George Island, Antarctic

Kim, JH Ahn, IY Hong, SG Andreev, M Lim, KM Oh, MJ Koh, YJ Hur, JS


As part of the long-term monitoring projects on Antarctic terrestrial vegetation in relation to global climate change, a lichen floristical survey was conducted around the Korean Antarctic Station (King Sejong Station), which is located on Barton Peninsula, King George Island, in January and February of 2006. Two hundred and twenty-five lichen specimens were collected and sixty-two lichen species in 38 genera were identified by morphological characteristics, chemical constituents, TLC analysis and ITS nucleotide sequence analysis.

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European phenological response to climate change matches the warming pattern

Menzel, A Sparks, TH Estrella, N Koch, E Aasa, A Ahas, R Alm-Kubler, K Bissolli, P Braslavska, O Briede, A Chmielewski, FM Crepinsek, Z Curnel, Y Dahl, A Defila, C Donnelly, A Filella, Y Jatcza, K Mage, F Mestre, A Nordli, O Penuelas, J Pirinen, P Remisova, V Scheifinger, H Striz, M Susnik, A Van Vliet, AJH Wielgolaski, FE Zach, S Zust, A


Global climate change impacts can already be tracked in many physical and biological systems; in particular, terrestrial ecosystems provide a consistent picture of observed changes. One of the preferred indicators is phenology, the science of natural recurring events, as their recorded dates provide a high-temporal resolution of ongoing changes. Thus, numerous analyses have demonstrated an earlier onset of spring events for mid and higher latitudes and a lengthening of the growing season. However, published single-site or single-species studies are particularly open to suspicion of being biased towards predominantly reporting climate change-induced impacts. No comprehensive study or meta-analysis has so far examined the possible lack of evidence for changes or shifts at sites where no temperature change is observed. We used an enormous systematic phenological network data set of more than 125 000 observational series of 542 plant and 19 animal species in 21 European countries (1971-2000). Our results showed that 78% of all leafing, flowering and fruiting records advanced (30% significantly) and only 3% were significantly delayed, whereas the signal of leaf colouring/fall is ambiguous. We conclude that previously published results of phenological changes were not biased by reporting or publication predisposition: the average advance of spring/summer was 2.5 days decade(-1) in Europe. Our analysis of 254 mean national time series undoubtedly demonstrates that species’ phenology is responsive to temperature of the preceding months (mean advance of spring/summer by 2.5 days degrees C-1, delay of leaf colouring and fall by 1.0 day degrees C-1). The pattern of observed change in spring efficiently matches measured national warming across 19 European countries (correlation coefficient r=-0.69, P < 0.001).

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The northern geographic range limit of the intertidal limpet Collisella scabra: a test of performance, recruitment, and temperature hypotheses

Gilman, SE

ECOGRAPHY 29:5 709-720

A decline in abundance towards a species’ range boundary is often interpreted as evidence of a decline in individual success, and is usually assumed to reflect a decline in suitable environmental conditions. Gradual declines towards high latitude range boundaries are frequently attributed to limitations on organismal tolerance of cold temperature. Rarely have these two assumptions been empirically tested. The intertidal gastropod Collisella scabra declines monotonically in abundance from 435 to < 1 m(-2) over the northern 300 km of its geographic distribution. I examined temperature, adult performance (survival, growth, reproduction), and recruitment at five locations in this region of decline. Mortality ranged from 4.9 to 11.2% per month, but was highest at the lowest latitude study site. Growth rates ranged from 0 to 5.2 mm yr(-1), but were generally lower at lower latitude sites. Gonad development was high in the three populations examined, but the possibility of infrequent spawning at high latitude sites could not be excluded. Finally, a comparison of performance differences among populations with temperature revealed clear effects of temperature on both growth and mortality; however, the patterns were not consistent with a hypothesis of cold stress at the range boundary. Overall there was little evidence for either reduced performance or increasing cold stress in low density high latitude populations. Over the same 300 km, recruitment declined monotonically from a mean of six recruits per 625 cm(2) to less than one; suggesting that limitations on recruitment, rather that adult performance, are responsible for low abundance in marginal populations. Several hypotheses for the decline in recruitment are discussed in the paper and the most likely explanation appears to be an increase in the distance between populations at the range margin, reducing the chances that dispersing larvae find suitable habitat for settlement.

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Seasonal resource availability and use by an endangered tropical mycophagous marsupial

Abell, SE Gadek, PA Pearce, CA Congdon, BC


This study highlights the importance of considering how seasonality of rainfall affects availability of resources and consequently species distributions within tropical ecosystems. The endangered northern bettong, Bettongia tropica Wakefield is thought to be restricted to habitats where seasonal availability of hypogeous fungi, their principal food resource, remains high. To test this hypothesis fungal abundance was quantified in the early wet, late wet, early dry and late dry seasons within known bettong habitat. A relationship was found between precipitation and fungal availability, with the abundance of hypogeous fungi being significantly lower in the late dry season. Fungal availability correlated strongly with the seasonal rainfall pattern determined from 74-year monthly means. This contrasts with a previous study where mycophagy, measured by faecal analysis, remained high across seasons presumably because of aseasonal rainfall during that study period. Alloteropsis semialata R.Br. (cockatoo grass) use by bettongs increased significantly during the period of low fungal availability. This suggests that the importance of cockatoo grass as an alternative food resource during annual and extended dry periods has previously been underestimated. With the frequency and intensity of drought expected to increase with global climate change, these findings have significant implications for bettong management. The important and possibly equivalent dependence of B. tropica on both hypogeous fungi and A. semialata helps to explain their habitat preference and identifies this species as a true ecotonal specialist. (c) 2006 Elsevier Ltd. All rights reserved.

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The PACE monitoring strategy: A concept for permafrost research in Qinghai-Tibet

King, L Herz, T Hartmann, H Hof, R Jiang, T Ke, C Wei, Z Liu, J Yi, C


Permafrost has been identified as one of six cryospheric indicators for global climate change within the monitoring framework of the World Meteorological Organisations Global Climate Observing System (GCOS). Vast areas of the Tibetan Plateau are underlain by predominantly warm permafrost, which is actually degrading due to a rise in mean surface temperatures caused by global warming. Because of the important role of surface temperature variations on the Tibetan Plateau for the onset and characteristic of the monsoon circulation over south-east Asia, it becomes evident that a consistent climate monitoring strategy in the region is urgently required. As permafrost reacts sensitively to changes in surface temperature, it is considered as a key variable in such a regional climate monitoring system. The Permafrost and Climate in Europe (PACE) project developed standardised methods for the monitoring of permafrost temperatures and distribution in European mountains, which are in good agreement with the site selection criteria of the GCOS Global Terrestrial Network-Permafrost (GTN-P). Following the PACE monitoring strategy, an international project “Permafrost and Climate in Tibet” is proposed. (c) 2006 Elsevier Ltd and INQUA. All rights reserved.

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The impact of increased environmental stochasticity due to climate change on the dynamics of asiatic wild ass

Saltz, D Rubenstein, DI White, GC


Theory proposes that increased environmental stochasticity negatively impacts population viability. Thus, in addition to the directional changes predicted for weather parameters under global climate change (GCC), the increase in variance of these parameters may also have a negative effect on biodiversity. As a case study, we assessed the impact of interannual variance in precipitation on the viability of an Asiatic wild ass (Equus hemionus) population reintroduced in Makhtesh Ramon Nature Reserve, Israel. We monitored the population from 1985 to 1999 to determine what environmental factors affect reproductive success. Annual precipitation during the year before conception, drought conditions during gestation, and population size determined reproductive success. We used the parameters derived from this model to assess population performance under various scenarios in a Leslie matrix type model with demographic and environmental stochasticity. Specifically, we used a change in the precipitation regime in our study area to formulate a GCC scenario and compared the simulated dynamics of the population with a no-change scenario. The coefficient of variation in population size under the global change scenario was 30% higher than under the no-change scenario. Minor die-offs (>= 15%) following droughts increased extinction probability nearly 10-fold. Our results support the idea that an increase in environmental stochasticity due to GCC may, in itself, pose a significant threat to biodiversity.

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Invasive grass reduces aboveground carbon stocks in shrublands of the Western US

Bradley, BA Houghtonw, RA Mustard, JF Hamburg, SP


Understanding the terrestrial carbon budget, in particular the strength of the terrestrial carbon sink, is important in the context of global climate change. Considerable attention has been given to woody encroachment in the western US and the role it might play as a carbon sink; however, in many parts of the western US the reverse process is also occurring. The conversion of woody shrublands to annual grasslands involves the invasion of non-native cheatgrass (Bromus tectorum) which in turn leads to increased frequency and extent of fires. We compared carbon storage in adjacent plots of invasive grassland and native shrubland. We scaled-up the impact of this ecosystem shift using regional maps of the current invasion and of the risk of future invasion. The expansion of cheatgrass within the Great Basin has released an estimated 8 +/- 3 Tg C to the atmosphere, and will likely release another 50 +/- 20 Tg C in the coming decades. This ecosystem conversion has changed portions of the western US from a carbon sink to a source, making previous estimates of a western carbon sink almost certainly spurious. The growing importance of invasive species in driving land cover changes may substantially change future estimates of US terrestrial carbon storage.

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