Vegetation impacts soil water content patterns by shaping canopy water fluxes and soil properties          下载免费PDF全文

Johanna Clara Metzger  Thomas Wutzler  Nicolas Dalla Valle  Janett Filipzik  Christoph Grauer  Robert Lehmann  Martin Roggenbuck  Danny Schelhorn  Josef Weckmüller  Kirsten Küsel  Kai Uwe Totsche  Susan Trumbore  Anke Hildebrandt 《水文研究》2017,31(22):3783-3795

Soil water content is a key variable for biogeochemical and atmospheric coupled processes. Its small‐scale heterogeneity impacts the partitioning of precipitation (e.g., deep percolation or transpiration) by triggering threshold processes and connecting flow paths. Forest hydrologists frequently hypothesized that throughfall and stemflow patterns induce soil water content heterogeneity, yet experimental validation is limited. Here, we pursued a pattern‐oriented approach to explore the relationship between net precipitation and soil water content. Both were measured in independent high‐resolution stratified random designs on a 1‐ha temperate mixed beech forest plot in Germany. We recorded throughfall (350 locations) and stemflow (65 trees) for 16 precipitation events in 2015. Soil water content was measured continuously in topsoil and subsoil (210 profiles). Soil wetting was only weakly related to net precipitation patterns. The precipitation‐induced pattern quickly dissipates and returns to a basic pattern, which is temporally stable. Instead, soil hydraulic properties (by the proxy of field capacity) were significantly correlated with this stable soil water content pattern, indicating that soil structure more than net precipitation drives soil water content heterogeneity. Also, both field capacity and soil water content were lower in the immediate vicinity of tree stems compared to further away at all times, including winter, despite stemflow occurrence. Thus, soil structure varies systematically according to vegetation in our site. We conclude that enhanced macroporosity increases gravity‐driven flow in stem proximal areas. Therefore, although soil water content patterns are little affected by net precipitation, the resulting soil water fluxes may strongly be affected. Specifically, this may further enhance the channelling of stemflow to greater depth and beyond the rooting zone.  相似文献   

Combined climatic and geological forcings on the spatio-temporal variability of piezometric levels in the chalk aquifer of Upper Normandy (France) at pluridecennal scale     

Smail Slimani  Nicolas Massei  Johanna Mesquita  Danièle Valdés  Matthieu Fournier  Benoît Laignel  Jean-Paul Dupont 《Hydrogeology Journal》2009,17(8):1823-1832

The temporal variability of water-level fluctuations in the chalk aquifer of Upper Normandy, France is constrained by natural climate fluctuations and is closely linked to the regional geological patterns. The chalk plateaus are covered with 5–50 m thick semi-permeable surficial formations; the thickness of the underlying chalk aquifer varies from 50 to 300 m. The relationship among climate oscillations, piezometric levels, and geologic structure were investigated by correlation, Fourier spectral, and continuous wavelet analyses of selected piezometric time-series data. Analysis focused on two piezometers located on the uplifted side of a major fault and two piezometers on the downthrown side. After generalization to other piezometers in the region, it was deduced that, in the downthrown compartments, a substantial aquifer and surficial formations thickness would imply a strong attenuation of annual variability, while multi-year variability is clearly expressed. Conversely, in the uplifted compartments, a thin layer of surficial formations and small thickness of the chalk authorizes strong variations on the annual mode with respect to the contribution of long-term climatic oscillations (multi-year variability). The results then demonstrated—and proposed a spatial determination of—the differential influence of geological patterns on the filtering of climate-induced oscillations in piezometric variability.  相似文献   

Are there social limits to adaptation to climate change?   总被引：1，自引：0，他引：1  

W. Neil Adger  Suraje Dessai  Marisa Goulden  Mike Hulme  Irene Lorenzoni  Donald R. Nelson  Lars Otto Naess  Johanna Wolf  Anita Wreford 《Climatic change》2009,93(3-4):335-354

While there is a recognised need to adapt to changing climatic conditions, there is an emerging discourse of limits to such adaptation. Limits are traditionally analysed as a set of immutable thresholds in biological, economic or technological parameters. This paper contends that limits to adaptation are endogenous to society and hence contingent on ethics, knowledge, attitudes to risk and culture. We review insights from history, sociology and psychology of risk, economics and political science to develop four propositions concerning limits to adaptation. First, any limits to adaptation depend on the ultimate goals of adaptation underpinned by diverse values. Second, adaptation need not be limited by uncertainty around future foresight of risk. Third, social and individual factors limit adaptation action. Fourth, systematic undervaluation of loss of places and culture disguises real, experienced but subjective limits to adaptation. We conclude that these issues of values and ethics, risk, knowledge and culture construct societal limits to adaptation, but that these limits are mutable.  相似文献   

Effects of climate change on oceanic fisheries in the tropical Pacific: implications for economic development and food security     

Johann D. Bell  Chris Reid  Michael J. Batty  Patrick Lehodey  Len Rodwell  Alistair J. Hobday  Johanna E. Johnson  Andreas Demmke 《Climatic change》2013,119(1):199-212

The four species of tuna that underpin oceanic fisheries in the tropical Pacific (skipjack, yellowfin, bigeye and albacore tuna) deliver great economic and social benefits to Pacific Island countries and territories (PICTs). Domestic tuna fleets and local fish processing operations contribute 3–20 % to gross domestic product in four PICTs and licence fees from foreign fleets provide an average of 3–40 % of government revenue for seven PICTs. More than 12,000 people are employed in tuna processing facilities and on tuna fishing vessels. Fish is a cornerstone of food security for many PICTs and provides 50–90 % of dietary animal protein in rural areas. Several PICTs have plans to (1) increase the benefits they receive from oceanic fisheries by increasing the amount of tuna processed locally, and (2) allocate more tuna for the food security of their rapidly growing populations. The projected effects of climate change on the distribution of tuna in the tropical Pacific Ocean, due to increases in sea surface temperature, changes in velocity of major currents and decreases in nutrient supply to the photic zone from greater stratification, are likely to affect these plans. PICTs in the east of the region with a high dependence on licence fees for government revenue are expected to receive more revenue as tuna catches increase in their exclusive economic zones. On the other hand, countries in the west may encounter problems securing enough fish for their canneries as tuna are redistributed progressively to the east. Changes in the distribution of tuna will also affect the proportions of national tuna catches required for food security. We present priority adaptations to reduce the threats to oceanic fisheries posed by climate change and to capitalise on opportunities.  相似文献   

Credited forest carbon sinks: how the cost reduction is allocated among countries and sectors     

Johanna Pohjola  Leena Kerkelä  Raisa Mäkipää 《Climate Policy》2013,13(4):445-461

Forest carbon sinks have been included in the Kyoto Protocol as one of the mechanisms for mitigating climate change. Consequently, credited sinks decrease the need to reduce emissions.We analyse in detail both the economywide and the sectoral effects of inclusion of carbon sinks as agreed upon in Bonn and Marrakesh for the first commitment period of 2008–2012. The focus of our analysis is the special treatment for Canada and Japan that allows them larger sinks. The analysis is performed with the multi-region computable general equilibrium (CGE) model GTAP-E.

New Zealand benefits most from the inclusion of sinks as it gains large carbon sinks from afforestation. Also in Sweden, Canada and Japan the costs of achieving the emission target are considerably reduced. Of these countries, only Canada has high costs without sinks. Thus credited sinks partly reduce the difference in economic burden of achieving the Kyoto target among countries. Even though larger sinks clearly benefit Canada and Japan, their effect on other countries, either on the economywide or on the sectoral level, remains marginal. Allowing larger sinks is, indeed, of relatively minor importance for the world economy and emission reduction, compared to the US withdrawal from the Kyoto Protocol.  相似文献   

Spatiotemporal changes in the size and shape of heat waves over North America     

David Keellings  Erin Bunting  Johanna Engström 《Climatic change》2018,147(1-2):165-178

Heat waves are occurring more frequently across the globe and are likely to increase in intensity and duration under climate change. Much work has already been completed on attributing causes of observed heat waves and on modeling their future occurrence, but such efforts are often lacking in exploration of spatial relationships. Based on principles of landscape ecology, we utilized fragmentation metrics to examine the spatiotemporal changes in heat wave shape and occurrence across North America. This methodological approach enables us to examine area, shape, perimeter, and other key metrics. The application of these shape metrics to high-resolution historical (1950–2013) climate data reveals that the total number and spatial extent of heat waves are increasing over the continent, but at an individual heat wave patch level, they are becoming significantly smaller in extent and more complex in shape, indicating that heat waves have become a more widespread and fragmented phenomena.  相似文献   

The Jurassic fossil plant record of the UK area     

Johanna H.A. van Konijnenburg-van Cittert 《Proceedings of the Geologists' Association. Geologists' Association》2008,119(1):59-72

  相似文献   

Values,climate change,and implications for adaptation: Evidence from two communities in Labrador,Canada     

Johanna Wolf  Ilana Allice  Trevor Bell 《Global Environmental Change》2013,23(2):548-562

Local material and symbolic values have to date remained underrepresented in climate change research and policy and this gap is particularly salient in places that have been identified as at significant risk from climate change. In such places, the dominant approach to understanding the effects of climate change has been centred on vulnerability; it has highlighted the social determinants of vulnerability and the differential and uneven distribution of effects. This approach cannot, however, illuminate the diverse and nuanced meanings people attach to specific aspects of their way of life, how the changing climate might affect these, and what this implies for adaptation. To address this gap, this empirical study uses the concept of values, defined as trans-situational conceptions of the desirable that give meaning to behaviour and events, and influence perception and interpretation of situations and events. We develop a set of values from 53 qualitative interviews in two remote communities in subarctic easternmost Canada. It draws on these values to frame how effects of climate change, specifically intangible and subjective effects, are felt, and how responses to them are imagined by those affected. The article argues that values are crucial in shaping perception of climate impacts and adaptation to them. Distinct values, such as tradition, freedom, harmony, safety, and unity shape different interpretations and meaning of impacts, and lead to distinct views on how to adapt to these. Conflicting and competing values can act as barriers to adaptation. The findings imply that adaptation research and policy need to address values explicitly if efforts for planned adaptation are to be perceived as legitimate and effective by those affected by the changing climate.  相似文献   

Variability of heat shock proteins and glutathione S-transferase in gill and digestive gland of blue mussel,Mytilus edulis     

Lyons C  Dowling V  Tedengren M  Gardeström J  Hartl MG  O'Brien N  van Pelt FN  O'Halloran J  Sheehan D 《Marine environmental research》2003,56(5):585-597

Glutathione S-transferase (GST) and heat shock proteins (hsps) 40, 60, 70 and 90 were determined by immunoblotting using actin as an internal control in Mytilus edulis from one station outside (site1) and three stations within (sites 2-4) Cork Harbour, Ireland. Comparisons were made between gill and digestive gland and between sites. Gill shows generally higher hsp 60, 70 and 90 while digestive gland has higher hsp 40. Site 1 showed higher gill hsps 40 and 70 than sites 2-4 while gill GST was higher in sites 3 and 4 than 1 and 2. Comparison with sites in the North Sea (site 5: outside Tj?rn? in The Koster archipelago in the Skagerack) and Baltic Sea (site 6: Ask? island) also revealed lower hsps 40 and 70 in site 6 (low salinity) than site 5 (high salinity) although hsps 60, 70 and 90 were detectable in digestive gland unlike sites 1-4. Previously, only hsp 70 had been studied at these sites [Mar. Environ. Res. 39. (1995), 181]. At the mRNA level, gill hsp 70 is 80-fold higher at Tj?rn? than Ask?. These data suggest that, while salinity may slightly decrease hsp 40 and 70, both hsp 70 and GST are selectively up-regulated by approx. 10- and 3-fold, respectively, at Tj?rn? compared to the other sites which we attribute to exposure to more widely fluctuating pollution levels.  相似文献   

The Dakhleh Glass: Product of an impact airburst or cratering event in the Western Desert of Egypt?     

Gordon R. OSINSKI  Johanna KIENIEWICZ  Jennifer R. SMITH  Mark B. E. BOSLOUGH  Mark ECCLESTON  Henry P. SCHWARCZ  Maxine R. KLEINDIENST  Albert F. C. HALDEMANN  Charles S. CHURCHER 《Meteoritics & planetary science》2008,43(12):2089-2107

Abstract— Impact cratering is a ubiquitous geological process on the terrestrial planets. Meteorite impact craters are the most visible product of impact events, but there is a growing recognition that large aerial bursts or airbursts should occur relatively frequently throughout geological time. In this contribution, we report on an unusual impact glass‐the Dakhleh Glass (DG)–which is distributed over an area of ?400 km ²of the Dakhleh Oasis, Egypt. This region preserves a rich history of habitation stretching back to over 400,000 years before the emergence of Homo sapiens. We report on observations made during recent fieldwork and subsequent analytical analyses that strengthen previous suggestions that the DG formed during an impact event. The wide distribution and large size of DG specimens (up to ?50 cm across), the chemistry (e.g., CaO and Al₂O₃ contents up to ?25 and ?18 wt, respectively), the presence of lechatelierite and burnt sediments, and the inclusion of clasts and spherules in the DG is inconsistent with known terrestrial processes of glass formation. The age and other textural characteristics rule out a human origin. Instead, we draw upon recent numerical modeling of airbursts to suggest that the properties of DG, coupled with the absence of a confirmed crater, can best be explained by melting of surficial sediments as a result of a large airburst event. We suggest that glass produced by such events should, therefore, be more common in the rock record than impact craters, assuming that the glass formed in a suitable preserving environment.  相似文献