Evidence for Longevity of Seeds and Microorganisms in Permafrost

The problem of whether seeds and microorganisms are able to remain viable in permanently frozen ground during a very long span of years was recently considered by Porsild et al. who germinated Lupinus arcticus seeds from fossil rodent burrows in permanently frozen silt deposited in a placer mining area in the Yukon Territory. Based on the geology of the locality, Porsild et al. estimated the age of the seeds to be at least 10,000 years. Moreover, in that and in previous papers Porsild suggests that seeds of Rorippa barbareaefolia, Descurainia sophioides, and Senecio congestus may be able to survive in permanently frozen silt as these species apparently are restricted to freshly disturbed soil within the placer mining districts. Discussing in general the problems of dating viable seeds in old deposits Godwin questions the dating of the Lupinus arcticus seeds because of the indirect method applied. In view of these studies and the investigations made by Ødum on the presence and age of viable seeds in Danish soils, Ester Creek placer mine west of Fairbanks, Alaska, was visited 16 to 19 July 1968. Some observations on the vegetation on the exposed silt and disturbed soil were made and soil samples were taken for further examination .... The contents of microorganisms in the soil samples were examined by using the dilution plate technique: 10 g of each sample were mixed with 90 ml of sterile water and placed on a shaking table for 20 minutes. Serial dilutions were made, and 0.1 ml of each of 10**-1, 10**-2, 10**-3 and 10**-4 suspensions were plated on Bengal Rose-, Sabouraud-, Cook-, and V-8-agar. Besides 1 ml of each suspension was added to test tubes with NIB. After one week of incubation at 4°C, 24°C, and 37°C the colonies were counted and the different strains isolated on slants with V-8-agar. The sample from the top soil showed c 10**3 fungi per g soil at 24° C, representing the following genera, known from similar localities: Cladosporium herbarum, Mortierella sp., Mucor circinelloides, Penicillium spp., Trichoderma viride, and unidentified, sterile imperfects and phycomycetes. ... Only a few investigations have been carried out to find living microorganisms in permanently frozen soil, and generally only the upper layers have been studied, because of the difficulties of sampling through permafrost. However Becker and Volkmannlo recovered 8 bacteria at 20 to 60 feet below the surface in permanently frozen soil near Fairbanks. Boyd and Boyd also studied permafrost soils from Barrow, Alaska, near Bison Lagoon, and found living bacteria at 8 to 15 feet. The distribution of Descurainia sophioides within the placer mine area and its extremely high frequency on the exposed muck does strongly support Porsild's theory. However, the fact that the seeds of the species are lacking in the investigated samples may lead to the alternative possibility that the ecology of the species is rather specific. Which factor or combination of factors is responsible for the germination and growth of the species on that particular substratum, ... cannot be determined without field experiments at the locality and further analyses; the high water content of the silt may appear to be a factor of importance. The investigation does not prove that viable seeds of Descurainia sophioides, Rorippa barbareaefolia, Senecio congestus or any other species are not present in permanently frozen soil; the negative result of the investigation, however, indicates that on this locality it is not very likely that they are present. ..

Short- and long-term impacts of Acacia longifolia invasion on the belowground processes of a Mediterranean coastal dune ecosystem

Many coastal dune ecosystems in Portugal are invaded by the leguminous tree Acacia longifolia (Andrews) Willd. This exotic species was first introduced over one hundred years ago in an effort to mitigate dune erosion and loss of coastal landscapes. However, since then A. longifolia has spread to new areas, displacing the native vegetation. These invaded ecosystems contrast with the native dune ecosystems that are typically dominated by herb and shrub communities. This study characterizes belowground changes to the native environment as a result of recent (20 y) by A. longifolia by analyzing a range of chemical and microbial parameters. Both invaded areas accumulated higher litter densities with greater N contents and lower C/N ratios than the native areas, which corresponded to lower C/N ratio and to higher potential rates of nitrification in the invaded soils. Long-term occupation by A. longifolia has significantly altered the soil properties with increased levels of organic C, total N and exchangeable cations resulting in higher microbial biomass, basal respiration, and [beta]-glucosaminidase activity. However, basal respiration and microbial biomass were significantly higher within recent invasion sites when calculated relative to soil organic C. The results from this study show that invasions by A. longifolia have altered the original native ecosystem processes and that the impacts are more pronounced within long-term invaded sites. A positive feedback mechanism is apparent for A. longifolia invading these Mediterranean dunes, which can make the restoration of native plant communities increasingly difficult with time elapsed since invasion.http://www.sciencedirect.com/science/article/B6T4B-4SM206B-1/1/bddafe50838e7acced911a3255e7827

Bedre offentlig sprogbrug: Gode hensigter rammer grum virkelighed

Det er en selvfølgelighed at offentlige myndigheder bør udtrykke sig let forståeligt. Men mange monopolorganisationer gør modstand mod forbedringer, og alt forbliver uændret når sprogkonsulenterne er draget videre efter at have modtaget organisationens officielle hyldest. Hvordan undgår vi at konsulenten og hendes produkter: kurser, pjecer, diasshows, innovationsforløb og teambuildingdage, ender som skueværdier og hyldesucceser uden at kommunikationen forbedres? Artiklen svarer på spørgsmålet ved at give et overblik over udviklingen i Danmark inden for sprog- og kommunikationsrådgivningen fra 1970 til i dag. En udvikling frem mod en mere effektiv rådgivning. SummaryIt is a truism that public authorities should express themselves clearly. But many monopoly organisations are resisting improvement, and everything remains unchanged after the language consultants have received official thanks and moved on. How do we prevent the consultants and their products – courses, brochures, slide shows, innovation processes and teambuilding days – ending up as advertised values and hollow successes without communication being improved? This article answers the question with an overview of developments in the field of language and communication consultancy in Denmark from 1970 to today: a trend towards more effective counselling

Tilgængelighed før og under rejsen

Manglende viden og negativ holdning er væsentlige årsager til, at mange ikke bruger den kollektive trafik. De vælger andre måder at transportere sig på. 40 trafikselskaber er i et UITP-projekt nået frem til, at der kan gøres noget ved det..Hvis man tilfører viden og måske endda får tvivlerne til at prøve den kollektive transport, giver det gode resultater. Det forudsætter naturligvis at basisproduktet er i orden, så fordommene nedbrydes. Arbejdet med at overbevise tvivlerne skal udføres af mange i forening, men hovedsagelig er det markedsføring og kundeservice, der skal trække store dele af slæbet. Markedsføringen skal få tvivlerne til at tro på, at det er værd at forsøge. Kundeservice skal med sine aktiviteter kvalificere tilgængeligheden før og under rejsen. Det er forskellige behov, der afgør, hvad der betragtes som tilgængelighed før og under rejsen, men helt adskilles kan behovene ikke. Den, der for første gang prøver den kollektive trafik, har primært behov for, forud for rejsen, nemt at finde ud af, hvordan man kommer fra A til B. Efterfølgende er der behov for tryghed i form af at blive bekræftet i, at rejsen afvikles som planlagt. Den, der dagligt benytter den kollektive trafik, f.eks. til og fra sit arbejde, kender sin rejsevej. Her er det primære behov at få information om forhold eller driftsforstyrrelser, der forhindrer at den sædvanlige rejse kan gennemføres. Der skal for begge gruppers vedkommende dækkes behov FØR og UNDER rejsen. Mulighederne for at dække disse behov er mange. Rigtig mange. I en tid hvor IT udvikler sig med rivende hast, er det ikke et spørgsmål om at finde muligheder nok, det er nærmere et spørgsmål om begrænsningens kunst. Leverandørerne af informationerne kan let lade sig gribe af de mange spændende muligheder. Store forkromede projekter sættes i værk - mange gange uden forinden at konstatere, om løsningen vil dække kundebehov eller, om det i det hele taget er en løsning, som kunderne finder rigtig. I iver efter at udnytte de sidste IT landvindinger ender mange projekter på så højt et stade at kun dem, der udvikler dem kan se et formål med dem