Causes of regional change—land cover

Anthropogenic land-cover change (ALCC) is one of the few climate forcings for which the net direction of the climate response over the last two centuries is still not known. The uncertainty is due to the often counteracting temperature responses to the many biogeophysical effects and to the biogeochemical versus biogeophysical effects. Palaeoecological studies show that the major transformation of the landscape by anthropogenic activities in the southern zone of the Baltic Sea basin occurred between 6000 and 3000/2500 cal year BP. The only modelling study of the biogeophysical effects of past ALCCs on regional climate in north-western Europe suggests that deforestation between 6000 and 200 cal year BP may have caused significant change in winter and summer temperature. There is no indication that deforestation in the Baltic Sea area since AD 1850 would have been a major cause of the recent climate warming in the region through a positive biogeochemical feedback. Several model studies suggest that boreal reforestation might not be an effective climate warming mitigation tool as it might lead to increased warming through biogeophysical processes

Potential future dynamics of carbon fluxes and pools in New England forests and their climatic sensitivities: A model-based study

Projections of terrestrial carbon (C) dynamics must account for interannual variation in ecosystem C exchange associated with climate change, increasing atmospheric CO2 concentration, and species dynamics. We used a dynamic ecosystem model to (i) project the potential dynamics of C in New England forests under nine climate change scenarios (CCSs) for the 21st century and (ii) examine the sensitivity of potential C dynamics to changes in climate and atmospheric CO2 concentration. Our results indicated that forest net primary productivity (NPP) and soil heterotrophic respiration (RH) averaged 428 and 279 gC/m2/yr and New England forests sequestered CO 2 by 149 gC/m2/yr in the baseline period (1971-2000). Under the nine future CCSs, NPP and RH were modeled to increase by an average rate of 0.85 and 0.56 gC/m2/yr2 during 1971-2099. The asymmetric increase in NPP and RH resulted in New England forests sequestering atmospheric CO2 at a net rate of 0.29 gC/m2/yr2 with increases in vegetation and soil C. Simulations also indicated that climate warming alone decreases NPP, resulting in a net efflux of C from forests. In contrast, increasing precipitation by itself stimulates CO 2 sequestration by forests. At the individual cell level, however, changes in temperature or precipitation can either positively or negatively affect consequent C dynamics. Elevation of CO2 levels was found to be the biggest driver for modeled future enhancement of C sequestration. Without the elevation of CO2 levels, climate warming has the potential to change New England forests from C sinks to sources in the late 21st century. ©2014. American Geophysical Union. All Rights Reserved

Changes in the geographical distribution and abundance of the tick Ixodes ricinus during the past 30 years in Sweden

<p>Abstract</p> <p>Background</p> <p><it>Ixodes ricinus </it>is the main vector in Europe of human-pathogenic Lyme borreliosis (LB) spirochaetes, the tick-borne encephalitis virus (TBEV) and other pathogens of humans and domesticated mammals. The results of a previous 1994 questionnaire, directed at people living in Central and North Sweden (Svealand and Norrland) and aiming to gather information about tick exposure for humans and domestic animals, suggested that <it>Ixodes ricinus </it>ticks had become more widespread in Central Sweden and the southern part of North Sweden from the early 1980s to the early 1990s. To investigate whether the expansion of the tick's northern geographical range and the increasing abundance of ticks in Sweden were still occurring, in 2009 we performed a follow-up survey 16 years after the initial study.</p> <p>Methods</p> <p>A questionnaire similar to the one used in the 1994 study was published in Swedish magazines aimed at dog owners, home owners, and hunters. The questionnaire was published together with a popular science article about the tick's biology and role as a pathogen vector in Sweden. The magazines were selected to get information from people familiar with ticks and who spend time in areas where ticks might be present.</p> <p>Results</p> <p>Analyses of data from both surveys revealed that during the near 30-year period from the early 1980s to 2008, <it>I. ricinus </it>has expanded its distribution range northwards. In the early 1990s ticks were found in new areas along the northern coastline of the Baltic Sea, while in the 2009 study, ticks were reported for the first time from many locations in North Sweden. This included locations as far north as 66°N and places in the interior part of North Sweden. During this 16-year period the tick's range in Sweden was estimated to have increased by 9.9%. Most of the range expansion occurred in North Sweden (north of 60°N) where the tick's coverage area doubled from 12.5% in the early 1990s to 26.8% in 2008. Moreover, according to the respondents, the abundance of ticks had increased markedly in LB- and TBE-endemic areas in South (Götaland) and Central Sweden.</p> <p>Conclusions</p> <p>The results suggest that <it>I. ricinus </it>has expanded its range in North Sweden and has become distinctly more abundant in Central and South Sweden during the last three decades. However, in the northern mountain region <it>I. ricinus </it>is still absent. The increased abundance of the tick can be explained by two main factors: First, the high availability of large numbers of important tick maintenance hosts, i.e., cervids, particularly roe deer (<it>Capreolus capreolus</it>) during the last three decades. Second, a warmer climate with milder winters and a prolonged growing season that permits greater survival and proliferation over a larger geographical area of both the tick itself and deer. High reproductive potential of roe deer, high tick infestation rate and the tendency of roe deer to disperse great distances may explain the range expansion of <it>I. ricinus </it>and particularly the appearance of new TBEV foci far away from old TBEV-endemic localities. The geographical presence of LB in Sweden corresponds to the distribution of <it>I. ricinus</it>. Thus, LB is now an emerging disease risk in many parts of North Sweden. Unless countermeasures are undertaken to keep the deer populations, particularly <it>C. capreolus </it>and <it>Dama dama</it>, at the relatively low levels that prevailed before the late 1970s - especially in and around urban areas where human population density is high - by e.g. reduced hunting of red fox (<it>Vulpes vulpes</it>) and lynx (<it>Lynx lynx</it>), the incidences of human LB and TBE are expected to continue to be high or even to increase in Sweden in coming decades.</p

A mechanistic ecohydrological model to investigate complex interactions in cold and warm water‐controlled environments: 1. Theoretical framework and plot‐scale analysis

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95321/1/jame60.pd

The Role of Vegetation-Climate Feedbacks in Regional Earth System Dynamics

The hypothesis of this thesis is that climate models should take structural vegetation changes that operate on interannual to centennial time scales into account in order to simulate climate change in a more realistic manner. To evaluate this hypothesis, a regional Earth System Model (ESM) has been developed, validated and applied over Europe. The model has enabled the identification of a number of regions where vegetation dynamics affect future climate, lending support to the hypothesis. The model, RCA-GUESS, combines the regional climate model RCA with the dynamic vegetation model LPJ-GUESS. RCA is continuously updated with dynamic albedo, leaf area index (LAI) and vegetated tile fractions for broadleaved and needleleaved forest and open land vegetation. These factors influence the radiation balance and the ratio between sensible and latent heat surface fluxes. The results suggest that it is important to account for vegetation-climate feedbacks in the analysis both of changes in mean climate and climate variability. Regarding mean climate, results indicate an accentuated temperature increase (winter, spring) in the Scandinavian Mountains as a result of tree line advance in response to warming. An increased forest fraction masks snow-covered areas, with a resulting albedo reduction. A significant temperature increase (summer) in southern Europe leads to a decline in LAI, resulting in a reduced evapotranspiration that reinforces the temperature increase. A less pronounced temperature rise in central Europe was attributed to the positive effect of "CO2 fertilization" on the simulated vegetation: a favourable effect on LAI positively impacts evapotranspiration, which dampens the temperature increase. The albedo effect in the Scandinavian Mountains dampens temperature variability, since variations in snow characteristics lose their significance beneath an increased forest fraction. In southern and central Europe, variability is strengthened, due to greater variations in temperature and water availability around bioclimatic limits governing establishment, growth and survival. Traditional climate models consider fast energy exchanges between the land surface and the atmosphere, utilizing a prescribed vegetation cover over time. A new generation of global ESMs are now including vegetation and the carbon cycling of the biosphere as interactive components. Such models have demonstrated that vegetation changes can result in strong feedbacks impacting on global climate. The course spatial resolution in global ESMs may, however, miss significant regional feedbacks. Regional ESMs are therefore important tools to consider for more accurate scenarios of future climate change when the focus is on the regional scale of, for example, Sweden or Europe

Hotspots of vegetation-climate feedbacks under future greenhouse forcing in Europe

We performed simulations of future biophysical vegetation-climate feedbacks with a regional Earth System Model, RCA-GUESS, interactively coupling a regional climate model and a process-based model of vegetation dynamics and biogeochemistry. Simulated variations in leaf area index and in the relative coverage of evergreen forest, deciduous forest, and open land vegetation in response to simulated climate influence atmospheric state via variations in albedo, surface roughness, and the partitioning of the land-atmosphere heat flux into latent and sensible components. The model was applied on a similar to 50 x 50 km grid over Europe under a future climate scenario. Three potential "hot spots" of vegetation-climate feedbacks could be identified. In the Scandinavian Mountains, reduced albedo resulting from the snow-masking effect of forest expansion enhanced the winter warming trend. In central Europe, the stimulation of photosynthesis and plant growth by "CO2 fertilization" mitigated warming, through a negative evapotranspiration feedback associated with increased vegetation cover and leaf area index. In southern Europe, increased summer dryness restricted plant growth and survival, causing a positive warming feedback through reduced evapotranspiration. Our results suggest that vegetation-climate feedbacks over the European study area will be rather modest compared to the radiative forcing of increased global CO2 concentrations but may modify warming projections locally, regionally, and seasonally, compared with results from traditional "off-line" regional climate models lacking a representation of the relevant feedback mechanisms

Kväveläckage inom Tolångaåns dräneringsområde : modellering och åtgärdssimulering

Human-induced eutrophication has rapidly become one of the most important environmental issues. The problem is largely due to the shift in agricultural practices. Farming methods have become more efficient during the last 300 years. Watercourses have been straightened out and wetlands have been reduced to increase agricultural landuse. Since the end of the 1940s, fertilization has increased dramatically. These factors have caused unnatural eutrophication and algae blooming in watercourses, lakes and ultimately the sea. In Sweden, the government has determined to reduce the nitrogen discharge by 50 percent by the year 2000. In order to accomplish this reduction companies and authorities have been assigned to find suitable reduction measures. The soils in Scania are among the most nutritious ones in Sweden. This along with high fertilization makes Scania a high risk area. In 1991, Ekologgruppen was assigned by the government to investigate the drainage area of the stream of Kävlingeån. Tolångaån constitutes a part of Kävlingeån and measurements of the water quality have been taking place since 1976 at Tolånga. As there were plenty of data available in this area the decision was made, in agreement with the county administrative board in Malmö, to study Tolångaån. The fact that the water finally reaches the lake of Vombsjön highlights the importance of establishing a good quality of the water. The lake serves as a source of water supply and provides parts of Scania with drinking-water. The study focuses on investigating the nitrogen situation in the stream and comparing measured values with simulated ones. Nitrogen simulation models are usefool tools, when making predictions of leakage. The model used in this study is based on the SOILN-model and simulates nitrogen dynamics and losses in the agricultural soil of the study area. SOILN was developed in the mid 80s and simulated leakage has shown good accuracy with observed measurements. The simulation was made over a ten-year period (1985-1994). The leakage from four different crops were simulated; ley, seed, rootcrops and oil plant. In addition, the effect of one measure to reduce leakage was simulated, the use of catch cropping. To illustrate the effect of the climate, one year with low precipitation (1989) and one year with high precipitation (1994) were compared. A trend analysis shows that nitrogen content in the watercourse has been fairly constant during the last two decades. However, the nitrogen content is far too high to be acceptable. When comparing measured values with simulated values adjustments had to be made. The simulated leakage was too high and a model parameter was evaluated in order to adjust the leakage. In spite of this, simulated values did not agree totally with measured values. This is probably due to the fact that the ground water model which is connected to the nitrogen model is too simple. When comparing the leakage caused by different crops, it turned out that ley had the best nitrogen uptake. Seed and root-crops were not as efficient as ley when it comes to assimlate nitrogen and contributed to most of the leakage. When simulating the effect of catchcrops it was possible to reduce nitrogen leakage by 30 percent. Previous studies have shown that catchcrop may reduce nitrogen leakage by 60 percent. The results from Tolånga and the simulation showed that precipitation is the parameter that has the greatest influence on the nitrogen leakage.Under de senaste 300 åren har jordbrukslandskapet i Sverige genomgått stora förändringar. I början av 1900-talet introducerades konstgödslet och efter andra världskriget ökade gödslingen dramatiskt i syfte att maximera produktionen. Detta har lett till att överskottet av kväve har spolats ut i vattendragen. I detta arbete har stor vikt lagts vid att skapa en egen kvävemodell i syfte att simulera kväveläckaget från jordbruksmarken i Tolångaåns dräneringsområde.Populärvetenskaplig sammanfattning: Under de senaste 300 åren har jordbrukslandskapet i Sverige genomgått stora förändringar. Detta började med att bönderna i slutet av 1600-talet erhöll en stor del av adelns jord. De fick således förvalta sin egen vinst, vilket resulterade i en rad nyodlingar och tekniska hjälpmedel. I början av 1900-talet introducerades konstgödslet och efter andra världskriget ökade gödslingen dramatiskt i syfte att maximera produktionen. I detta skede införde många gårdar kreaturslös drift vilket gjorde att den tidigare balansen mellan nötkreatur, vall (bete) och spannmålsproduktion inte längre fanns kvar. Följden blev att vallarealen minskade och att bönderna köpte gödslet utifrån, ofta i form av konstgödsel. För att erhålla så mycket jordbruksmark som möjligt har rationaliseringar av olika slag genomförts av jordbrukslandskapet. Olika typer av odlingshinder såsom våtmarker, vattendrag och olika form av vegetation har tagits bort. Långa sträckor av tidigare öppna vattendrag och dräneringsdiken har lagts i kulvertar och rör. Detta har lett till att det kväve (i form av stallgödsel eller konstgödsel) som inte tas upp av grödorna spolas ut i vattendragen och slutligen ut till våra sjöar och hav För att bestämma hur mycket kväve som tillförs vattendragen utförs mätningar i olika forskningsprojekt runt om i landet. Dessa fältmätningar är ofta avancerade och kostnadskrävande, vilket omöjliggör övervakning av stor delar av den svenska åkermarken. Modellering, med vilket kvävets dynamik samt förluster kan simuleras, utgör därför ett bra alternativ till fältmätningar. I detta arbete har stor vikt lagts vid att skapa en egen kvävemodell i syfte att simulera kväveläckaget från jordbruksmarken i Tolångaåns dräneringsområde. Tolångaån utgör ett tillflöde till Vombsjön och ingår i Kävlingeåns dräneringsområde. Modellen tillverkades genom att studera kvävets kretslopp och genom att ta reda på hur mycket gödsel samt atmosfärisk kvävedepostition som tillförs marken. Kvävet i marken är lagrat i två former; oorganiskt (mineraliskt) eller organiskt. Det oorganiska kvävet är lagrat i form av ammonium och nitrat. Omfördelning av kväve sker hela tiden mellan de olika magasinen i marken och detta styrs av hur stor mängd lättillgänglig organisk substans (kol) som finns. Eftersom kolet har en avgörande betydelse för kvävets omvandling i marken kopplades en separat kolmodell till kvävemodellen. Markvattnet spelar också en central roll när det gäller kväveutlakningen, eftersom kvävet (nitrat) följer med det perkolerande vattnet ut till vattendragen. Simuleringen av mängden markvatten gjordes därför också i en separat modell. Kvävesituationen i Tolångaån studerades för åren 1976-1997 och en trendanalys av uppmätta kvävehalter visade att kvävehalterna har varit relativt konstanta under hela mätperioden. Modellen ovan applicerades på det uträknade dräneringsområdet runt Tolångaån. Uppmätta och simulerade kvävetransporter visade sig stämma bra överens vissa år medan skillnaden var stor andra år. Skillnader kan exempelvis bero på att det i verkligheten kan ha förekommit felmätningar eller punktutsläpp av kväve, vilket modellen inte kan ta hänsyn till. Hur stort kväveläckaget blir beror på många faktorer såsom klimat, jordart, vilken gröda som odlas, tid på året och framför allt på nederbördsmängd. För att se hur stor effekt klimatet utgör jämfördes ett nederbördsfattigt år (1989) och ett nederbördsrikt år (1994). Omfattande nederbörd tenderar att laka ut stora mängder kväve, vilket bekräftades vid jämförelse av de båda åren. Eftersom olika grödor har olika kvävebehov och således orsakar olika mycket utlakning, undersöktes även hur stor andel de olika grödorna står för i området. Grödorna delades in i vall, oljeväxter, rotfrukter och säd. Vall och oljeväxter visade sig enligt simuleringsresultaten stå för den minsta utlakningen. De är sålunda bra att odla i områden som har höga utlakningssiffror. Rotfrukter och säd är däremot inte alls lika effektiva att ta upp kväve och högre utlakningssiffror erhålls

From contamination to infective endocarditis—a population-based retrospective study of Corynebacterium isolated from blood cultures

Corynebacterium is a genus that can contaminate blood cultures and also cause severe infections like infective endocarditis (IE). Our purpose was to investigate microbiological and clinical features associated with contamination and true infection. A retrospective population-based study of Corynebacterium bacteremia 2012–2017 in southern Sweden was performed. Corynebacterium isolates were species determined using a matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS). Patient were, from the medical records, classified as having true infection or contamination caused by Corynebacterium through a scheme considering both bacteriological and clinical features and the groups were compared. Three hundred thirty-nine episodes of bacteremia with Corynebacterium were identified in 335 patients of which 30 (8.8%) episodes were classified as true infection. Thirteen patients with true bacteremia had only one positive blood culture. Infections were typically community acquired and affected mostly older males with comorbidities. The focus of infection was most often unknown, and in-hospital mortality was around 10% in both the groups with true infection and contamination. Corynebacterium jeikeium and Corynebacterium striatum were significantly overrepresented in the group with true infection, whereas Corynebacterium afermentans was significantly more common in the contamination group. Eight episodes of IE were identified, all of which in patients with heart valve prosthesis. Six of the IE cases affected the aortic valve and six of seven patients were male. The species of Corynebacterium in blood cultures can help to determine if a finding represent true infection or contamination. The finding of a single blood culture with Corynebacterium does not exclude true infection such as IE

A model of the coupled dynamics of climate, vegetation and terrestrial ecosystem biogeochemistry for regional applications

Regional climate models (RCMs) primarily represent physical components of the climate system, omitting vegetation dynamics, ecosystem biogeochemistry and their associated feedbacks. To account for such feedbacks, we implemented a novel plant individual-based vegetation dynamics-ecosystem biogeochemistry scheme within the RCA3 RCM. Variations in leaf area index (LAI) of seven plant functional type (PFTs) in response to physical forcing and evolving vegetation state feed back to climate via adjustments in surface energy fluxes and surface properties. In an ERA-40- driven simulation over Europe, the model reproduces the recent past climate with comparable accuracy to the standard RCM. Large-scale patterns of LAI, net primary production and vegetation composition were comparable with observations, although winter LAI was systematically overestimated compared to satellite estimates. Analysis of the ERA-40 simulation and an A1B climate-change simulation revealed considerable covariation among dynamic variables of the physical climate and vegetation. At a Mediterranean site, periodic soil water limitation led to fluctuations in leaf cover and a likely positive feedback to near-surface temperature. At an alpine site, rising temperatures led to forest advance onto tundra areas, reducing albedo and effecting a likely positive feedback on temperature. Climate–vegetation coupling was less pronounced but still apparent at intermediate temperate and boreal sites