Global Change Abstracts The Swiss Contribution - SCNAT

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86 had increased, indicating more intense mixing. This species-specific mixing of new with old C pools is likely to mask year- or season-specific linkages between tree ring formation and climate and has considerable implications for climate reconstruction using stable isotopes as proxies for past climatic conditions. Plant Cell and Environment, 2007, V30, N8, AUG, pp 963-972. 08.1-133 Identifying the early genetic consequences of habitat degradation in a highly threatened tropical conifer, Araucaria nemorosa Laubenfels Kettle C J, Hollingsworth P M, Jaffre T, Moran B, Ennos R A Switzerland, Scotland, New Caledonia Biodiversity , Ecology , Plant Sciences , Forestry The early genetic effects of habitat degradation were investigated in the critically endangered conifer Araucaria nemorosa. This species occurs in New Caledonia, a global biodiversity hotspot where the world’s greatest concentration of endemic conifer species coincides with an extremely high level of habitat destruction due to fire and mining. Using seven microsatellite loci, estimates were made of genetic marker variation, inbreeding coefficients and population differentiation of adult and seedling cohorts of A. nemorosa. These were contrasted with equivalent estimates, made over similar spatial scales and with the same marker loci, in the locally common and more widespread sister species Araucaria columnaris. There were no significant differences in population genetic parameters between adult populations of the two species, despite their different abundances. However, in A. nemorosa, the juvenile cohort showed a loss of rare alleles and elevated levels of inbreeding when compared to the adult cohort. These genetic differences between the cohorts were not observed in the locally common A. columnaris. This suggests that recent environmental degradation is influencing the genetic structure of A. nemorosa populations. Although this is not detectable among predisturbance adult populations, an early warning of these impacts is evident in more recently established seedling cohorts. The conservation implications of these results are discussed. Molecular Ecology, 2007, V16, N17, SEP, pp 3581-3591. Global Change Abstracts – The Swiss Contribution | Terrestrial Ecosystems 08.1-134 Arbuscular mycorrhizal symbiosis can counterbalance the negative influence of the exotic tree species Eucalyptus camaldulensis on the structure and functioning of soil microbial communities in a sahelian soil Kisa M, Sanon A, Thioulouse J, Assigbetse K, Sylla S, Spichiger R, Dieng L, Berthelin J, Prin Y, Galiana A, Lepage M, Duponnois R Senegal, France, Switzerland, Burkina Faso Forestry , Plant Sciences , Agriculture, Soil Sciences , Microbiology The hypothesis of the present study was that bacterial communities would differentiate under Eucalyptus camaldulensis and that an enhancement of arbuscular mycorrhizal (AM) density would minimize this exotic plant species effect. Treatments consisted of control plants, preplanting fertilizer application and AM inoculation. After 4 months of culture in autoclaved soil, E. camaldulensis seedlings were either harvested for growth measurement or transferred into containers filled with the same soil but not sterilized. Other containers were kept without E. camaldulensis seedlings. After 12 months, effects of fertilizer amendment and AM inoculation were measured on the growth of Eucalyptus seedlings and on soil microbial communities. The results clearly show that this plant species significantly modified the soil bacterial community. Both community structure (assessed by denaturing gradient gel electrophoresis profiles) and function (assessed by substrateinduced respiration responses including soil catabolic evenness) were significantly affected. Such changes in the bacterial structure and function were accompanied by disturbances in the composition of the herbaceous plant species layer. These results highlight the role of AM symbiosis in the processes involved in soil bio-functioning and plant coexistence and in afforestation programmes with exotic tree species that target preservation of native plant diversity. Fems Microbiology Ecology, 2007, V62, N1, OCT, pp 32-44. 08.1-135 Response of net ecosystem productivity of three boreal forest stands to drought (vol 9, pg 1128, 2006) Kljun N, Black T A, Griffis T J, Barr A G, Gaumont Guay D, Morgenstern K, Mccaughey J H, Nesic Z Canada, USA, Switzerland Forestry , Plant Sciences , Ecology In 2000-03, continuous eddy covariance measurements of carbon dioxide (CO 2) flux were made above mature boreal aspen, black spruce, and jack
Global Change Abstracts – The Swiss Contribution | Terrestrial Ecosystems 87 pine forests in Saskatchewan, Canada, prior to and during a 3- year drought. During the 1st drought year, ecosystem respiration (R) was reduced at the aspen site due to the drying of surface soil layers. Gross ecosystem photosynthesis (GEP) increased as a result of a warm spring and a slow decrease of deep soil moisture. These conditions resulted in the highest annual net ecosystem productivity (NEP) in the 9 years of flux measurements at this site. During 2002 and 2003, a reduction of 6% and 34% in NEP, respectively, compared to 2000 was observed as the result of reductions in both R and GEP, indicating a conservative response to the drought. Although the drought affected most of western Canada, there was considerable spatial variability in summer rainfall over the 100-km extent of the study area; summer rainfalls in 2001 and 2002 at the two conifer sites minimized the impact of the drought. In 2003, however, precipitation was similarly low at all three sites. Due to low topographic position and consequent poor drainage at the black spruce site and the coarse soil with low water-holding capacity at the jack pine site almost no reduction in R, GEP, and NEP was observed at these two sites. This study shows that the impact of drought on carbon sequestration by boreal forest ecosystems strongly depends on rainfall distribution, soil characteristics, topography, and the presence of vegetation that is well adapted to these conditions. Ecosystems, 2007, V10, N6, SEP, pp 1039-1055. 08.1-136 Assessment of land use impacts on the natural environment - Part 2: Generic characterization factors for local species diversity in central Europe Köllner T, Scholz R W Switzerland Agriculture, Soil Sciences , Biodiversity , Ecology Goal, Scope and Background. Land use is an economic activity that generates large benefits for human society. One side effect, however, is that it has caused many environmental problems throughout history and still does today. Biodiversity, in particular, has been negatively influenced by intensive agriculture, forestry and the increase in urban areas and infrastructure. Integrated assessment such as Life Cycle Assessment (LCA), thus, incorporate impacts on biodiversity. The main objective of this paper is to develop generic characterization factors for land use types using empirical information on species diversity from Central Europe, which can be used in the assessment method developed in the first part of this series of paper. Methods. Based on an extensive meta-analysis, with information about species diversity on 5581 sample plots, we calculated characterization factors for 53 land use types and six intensity classes. The typology is based on the CORINE Plus classification. We took information on the standardized alpha-diversity of plants, moss and mollusks into account. In addition, threatened plants were considered. Linear and nonlinear models were used for the calculation of damage potentials (EDPs). In our approach, we use the current mean species number in the region as a reference, because this determines whether specific land use types hold more or less species diversity per area. The damage potential calculated here is endpoint oriented. The corresponding characterization factors EDPs can be used in the Life Cycle Impact Assessment as weighting factors for different types of land occupation and land use change as described in Part 1 of this paper series. Results. The result from ranking the intensity classes based on the mean plant species number is as expected. High intensive forestry and agriculture exhibit the lowest species richness (5.7-5.8 plant species/m(2)), artificial surfaces, low intensity forestry and non- use have medium species richness (9.4-11.1 plant species/m2) and low- intensity agriculture has the highest species richness (16.6 plant species/m(2)). The mean and median are very close, indicating that the skewedness of the distribution is low. Standard error is low and is similar for all intensity classes. Linear transformations of the relative species numbers are linearly transformed into ecosystem damage potentials (EDPlinears). The inte gration of threatened plant species diversity into a more differentiated damage function EDPlinearStotal makes it possible to differentiate between land use types that have similar total species numbers, but intensities of land use that are clearly different (e.g., artificial meadow and broad-leafed forest). Negative impact values indicate that land use types hold more species per m(2) than the reference does. In terms of species diversity, these land use types are superior (e.g. near-to- nature meadow, hedgerows, agricultural fallow). Discussion. Land use has severe impacts on the environment. The ecosystem damage potential EDPS is based on assessment of impacts of land use on species diversity. We clearly base EDPs factors on alpha- diversity, which correlates with the local aspect of species diversity of land use types. Based on an extensive meta-analysis of biologists’ field research, we were able to include data on the diversity of plant species, threatened plant species, moss and mollusks in the EDPS. The integration of other animal species groups (e.g. insects, birds, mammals, amphibians) with
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