Resilience and vulnerability of northern regions to social and environmental change

The arctic tundra and boreal forest were once considered the last frontiers on earth because of their vast expanses remote from agricultural land-use change and industrial development. These regions are now, however, experiencing environmental and social changes that are as rapid as those occurring anywhere on earth. This paper summarizes the role of northern regions in the global system and provides a blueprint for assessing the factors that govern their sensitivity to social and environmental change.     

Circuit-theory applications to connectivity science and conservation

Conservation practitioners have long recognized ecological connectivity as a global priority for preserving biodiversity and ecosystem function. In the early years of conservation science, ecologists extended principles of island biogeography to assess connectivity based on source patch proximity and other metrics derived from binary maps of habitat. From 2006 to 2008, the late Brad McRae introduced circuit theory as an alternative approach to model gene flow and the dispersal or movement routes of organisms. He posited concepts and metrics from electrical circuit theory as a robust way to quantify movement across multiple possible paths in a landscape, not just a single least-cost path or corridor. Circuit theory offers many theoretical, conceptual, and practical linkages to conservation science. We reviewed 459 recent studies citing circuit theory or the open-source software Circuitscape. We focused on applications of circuit theory to the science and practice of connectivity conservation, including topics in landscape and population genetics, movement and dispersal paths of organisms, anthropogenic barriers to connectivity, fire behavior, water flow, and ecosystem services. Circuit theory is likely to have an effect on conservation science and practitioners through improved insights into landscape dynamics, animal movement, and habitat-use studies and through the development of new software tools for data analysis and visualization. The influence of circuit theory on conservation comes from the theoretical basis and elegance of the approach and the powerful collaborations and active user community that have emerged. Circuit theory provides a springboard for ecological understanding and will remain an important conservation tool for researchers and practitioners around the globe.     

Root-surface phosphatase activity in shrublands across a European gradient: effects of warming

Root-surface phosphatase activities were measured in natural and semi-natural shrublands across an European climatic gradient of temperature and rainfall including Wales (WL), Denmark (DK), Netherlands (NL), Hungary (HU), Italy (IT) and Spain (SP). In each site a warming experiment was conducted since 1999 or 2001 by means of passive night-time warming using reflective curtains that covered the vegetation at night. The treatments increased yearly average soil temperatures around 0. 8 degrees C in most of sites. Root-surface phosphatase activity values ranged between 56 mg PNP g(-1) h(-1) in IT and 3.5 mg PNP g(-1) h(-1) in HU. Warming had no effect on root-surface phosphatase activity across the sites and only in Hungary a slight increase was detected. Plants at Mediterranean sites (IT, SP) showed a higher root-surface phosphatase activity than plants at temperate sites (WL, NL, DK). We suggest it might be an adaptation of plant species evolved under Mediterranean climate that allows them a) to compensate in wet period for the decrease in phosphatase activity, and thus P uptake, during drought periods, and/or b) to benefit from soluble organic P flushes following the frequent drying-rewetting episodes experienced by soils in Mediterranean ecosystems.     

Microbial biotransformation of aryl sulfanylpentafluorides

We report, for the first time, the biotransformation of potential pollutants bearing the pentafluorosulfanyl (SF₅-) functional group in a fungus and bacteria. Cunninghamella elegans transformed p-methoxy phenyl SF₅ via demethylation; Pseudomonas knackmussii and P. pseudoalcaligenes KF707 transformed amino-, hydroxyamino- and diamino- substituted phenyl SF₅, forming the N-acetylated derivatives as the main product. Cell-free extract of Streptomyces griseus transformed 4-amino-3-hydroxy-phenyl SF₅ to the N-acetylated derivative in the presence of acetyl CoA, confirming that an N-acetyltransferase is responsible for the bacterial biotransformations. Approximately 25 % of drugs and 30 % of agrochemicals contain fluorine, and the trifluoromethyl group is a prominent feature of many of these since it improves lipophilicity and stability. The pentafluorosulfanyl substituent is seen as an improvement on the trifluoromethyl group and research efforts are underway to develop synthetic methods to incorporate this moiety into biologically active compounds. It is important to determine the potential environmental impact of these compounds, including the potential biotransformation reactions that may occur when they are exposed to microorganisms.     

Determining Minimum Habitat Areas and Habitat Corridors for Cougars

I simulated population dynamics of cougars to predict the minimum areas and levels of immigration needed to avoid population extinction caused by demographic and environmental stochasticity for a period of 100 years. Under most plausible parameter values, the model predicted very low extinction risk in areas as small as 2200 km², and (in the absence of immigration) increasing risk as area decreased below 2200 km². If as few as one to four animals per decade could immigrate into a small population, the probability of population persistence increased markedly. Thus a corridor for immigration will benefit a small population in an area where further loss of habitat will occur. The model was applied to the cougar population in the Santa Ana Mountain Range of southern California (2070 km², with about 20 adults). Field data support the model’s conclusion that this population is demographically unstable. There will be a high risk of extinction if the habitat is reduced to currently protected and connected areas (1114 km²). A movement corridor allowing immigration from the adjacent population and intra-range corridors would greatly enhance the prognosis. However, the last corridor for immigration has been degraded by recent human activity. Within the mountain range, cougars recently became extinct in a 75 km² habitat fragment recently isolated by development, and cougars will become extinct in another 150 km² of habitat if a proposed housing project occludes a critical corridor. Radio tracking has confirmed use of this and other important corridors. Neither the model nor the field data alone would have much influence in the face of development pressure; together they have stimulated interest in restoring and protecting critical corridors in this range. Nonetheless, the long-term prognosis for this populations is bleak, because 22 local governments review potential impact on a case-by-case basis. Effective land-use planning must be spatially explicit and regional in scope. Because cougars need corridors and because telemetered cougars can quickly identify movement corridors, cougar research is an efficient and appropriate way to inject biological data into such planning efforts.     

Effects of Climate and Ecosystem Disturbances on Biogeochemical Cycling in a Semi-Natural Terrestrial Ecosystem

The effects of increased temperature and potential ecosystem disturbances on biogeochemical cycling were investigated by manipulation of temperature in a mixed Calluna/grass heathland in Denmark. A reflective curtain covered the vegetation during the night to reduce the heat loss of IR radiation from the ecosystem to the atmosphere. This `night time warming' was done for 3 years and warmed the air and soil by 1.1 °C. Warming was combined with ecosystem disturbances, including infestation by Calluna heather beetles (Lochmaea suturalis Thompson) causing complete defoliation of Calluna leaves during the summer 2000, and subsequent harvesting of all aboveground biomass during the autumn. Small increases in mineralisation rates were induced by warming and resulted in increased leaching of nitrogen from the organic soil layer. The increased nitrogen leaching from the organic soil layer was re-immobilised in the mineral soil layer as warming stimulated plant growth and thereby increased nitrogen immobilisation. Contradictory to the generally moderate effects of warming, the heather beetle infestation had very strong effects on mineralisation rates and the plant community. The grasses completely out-competed the Calluna plants which had not re-established two years after the infestation, probably due to combined effects of increased nutrient availability and the defoliation of Calluna. On the short term, ecosystem disturbances may have very strong effects on internal ecosystem processes and plant community structure compared to the more long-term effects of climate change.     

A method for classifying multidimensional data with respect to uncertainties of measurement and its application to archaeometry

This study was supported by the Bundesministerium für Forschung und Technologie (BMFT), core program Einsatz neuer Technologien in den Geisteswissenschaften.