Leita ķ fréttum mbl.is

Sprengingar og hrun ķ Mżvatni

Lķfrķki Mżvatns er mjög sérstakt, mżiš er ķ AŠAL hlutverki ķ vistkerfinu. Įrni Einarsson, forstöšumašur rannsóknarsetursins viš Mżvatn, og Arnžór Garšarson viš Lķffręšiskor HĶ, hafa um įratuga skeiš męlt višgang mżflugnanna, og annara lķfvera ķ vatninu. Slķkar langtķma rannsóknir krefjast mikillar žolinmęši, og mannafla, og eru žeir ófįir įhugamenn, fręšingar og nemar sem hafa lagt hönd į hįfinn (sżnatökudall hljómar ekki jafnvel).

Įrni, Arnžór og félagar hafa veriš virkir ķ rannsóknum į žessu vistkerfi en grein žeirra ķ Nature įriš 2008 er einn hįpunkturinn į góšu verkefni. Ķ greininni nutu žeir ašstošar erlendra lķkanasmiša, sem snišu reiknilķkön sem śtskżra įgętlega sveiflur ķ mżstofninum į Mżvatni. Anthony Ragnar Ives smķšaši lķkan til aš fylgja eftir sveiflum į mörkušum eša hreyfingum gervitungla, eins og lżst er ķ pistli ķ Nature. Vincent Jensen ašstošar žį aš tślka herlegheitin.

Megin nišurstašan er sś aš stofninn sveiflist milli tvennskonar įstanda. Annars vegar rótękar sveiflur ķ stęrš, sem fólk kannast viš, stundum er Mżvatn nęr ósżnilegt aš sumarlagi, en önnur įrin stendur žaš varla undir nafni. Hins vegar getur stofnstęršin stundum hangiš stöšug um nokkura įra skeiš. Lķkaniš sem žeir byggšu getur śtskżrt hvorutveggja.

Žaš sem skiptir nįttśrulega mestu er žaš aš vistkerfi eru ekki stöšug, og aš stundum geta žau hruniš, oft af veigalitlum orsökum. Žaš ętti aš vera įstęša til žess aš draga śr veigameira įlagi į vistkerfi, sem eru okkur naušsynleg lifibrauš. 

Tony Ragnar Ives heldur fyrirlestur um Mżvatn föstudaginn 20. aprķl, 12:30 ķ stofu 131 i Öskju nįttśrufręšihśsi HĶ. Allir velkomnir.

Booms and busts in the midges of Mżvatn

Kynning og įgrip į ensku

Anthony Ragnar Ives, Professor of Biological Sciences and head of the Ives lab at University of Wisconsin-Madison, will give a presentation of his research:

Ecosystems that show huge changes through time can reveal the ecological forces that stabilize or destabilize natural systems. Midges in Lake Mżvatn, Iceland, are an extreme example, with abundances that fluctuate over four orders of magnitude in irregular cycles lasting 4-8 years. Based on research conducting for over 40 years, we suspect that these fluctuations are caused by the midges' ability to deplete their food supply. If this hypothesis is correct, then Mżvatn will be a rare example in which the interactions between herbivores and their food create a highly unstable ecosystem.

Ķtarefni:

Lķfiš ķ hrauninu – lķfrķki ķ vatnsfylltum hraunhellum ķ Mżvatnssveit

Lķf og įstir viš eldfjallavatn

Nįttśra ķ jafnvęgi? Veišiskapur ķ Mżvatni ķ 150 įr

Til heišurs Arnžóri Garšarssyni


Hvaš gerist į tśndrunni viš hlżnun jaršar?

Tśndran er margslungin, fįtęk af tegundum en aušug af lķfmassa, stöšug en einnig viškvęm og hśn er eitt mikilvęgasta vistkerfiš sem veršur fyrir įhrifum hnattręnna loftslagsbreytinga.

Föstudagnn 13. aprķl kl. 12.30 ķ Öskju N-131, mun Ingibjörg Svala Jónsdóttir, prófessor viš Lķf- og umhverfisvķsindadeild, kynna rannsóknir sķnar ķ fyrirlestrarröš Lķffręšistofu:

Erindi hennar veršur flutt į ensku, og nefnist Phenological responses to climate warming across the tundra biome

a_141.jpgĮgrip erindis birtist einnig į vefsķšu lķffręšistofu HĶ.

During more than two decades valuable data has been collected within the research network International Tundra Experiment (ITEX) aiming at answering the question how climate warming affects tundra plant communities and ecosystems. The large number of research sites widely distributed across the tundra biome, the use of standardized protocols and the combination of experimental warming and monitoring make this network unique. Several data syntheses have provided groundbreaking insights into how climate warming affects growth and reproduction of individual tundra plants and tundra plant communities. In this talk I will focus on more recent synthesis of phenological data. As expected, they show that warming accelerates phenology in general. Furthermore, the syntheses reveal that plants at colder sites (high Arctic) are more sensitive to a given increase in summer temperatures than plants at warmer sites (low Arctic and Alpine), that warming shortens the flowering season for Arctic and alpine plants and more so for late flowering species than early flowering. I will discuss the implications of these differential phenological responses to warming for plant reproductive success, plant establishment and trophic interactions in tundra ecosystems.

Dagskrį föstudagsfyrirlestra Lķffręšistofu


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