University of Aberdeen

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Article: Interpreting nitrogen pollution thresholds for sensitive habitats: the importance of concentration versus dose.

I S K Pearce, R Van der Wal

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ABSTRACT: Nitrate and ammonium concentration in wet deposition detrimentally impacted a sensitive pollution indicator species irrespective of the nitrogen dose.

Environmental Pollution 04/2008; 152(1):253-6.
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Article: Arctic mosses govern below-ground environment and ecosystem processes.

J L Gornall, I S Jónsdóttir, S J Woodin, R Van der Wal

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ABSTRACT: Mosses dominate many northern ecosystems and their presence is integral to soil thermal and hydrological regimes which, in turn, dictate important ecological processes. Drivers, such as climate change and increasing herbivore pressure, affect the moss layer thus, assessment of the functional role of mosses in determining soil characteristics is essential. Field manipulations conducted in high arctic Spitsbergen (78 degrees N), creating shallow (3 cm), intermediate (6 cm) and deep (12 cm) moss layers over the soil surface, had an immediate impact on soil temperature in terms of both average temperatures and amplitude of fluctuations. In soil under deep moss, temperature was substantially lower and organic layer thaw occurred 4 weeks later than in other treatment plots; the growing season for vascular plants was thereby reduced by 40%. Soil moisture was also reduced under deep moss, reflecting the influence of local heterogeneity in moss depth, over and above the landscape-scale topographic control of soil moisture. Data from field and laboratory experiments show that moss-mediated effects on the soil environment influenced microbial biomass and activity, resulting in warmer and wetter soil under thinner moss layers containing more plant-available nitrogen. In arctic ecosystems, which are limited by soil temperature, growing season length and nutrient availability, spatial and temporal variation in the depth of the moss layer has significant repercussions for ecosystem function. Evidence from our mesic tundra site shows that any disturbance causing reduction in the depth of the moss layer will alleviate temperature and moisture constraints and therefore profoundly influence a wide range of ecosystem processes, including nutrient cycling and energy transfer.

Oecologia 11/2007; 153(4):931-41.
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Article: Invasive plant suppresses charismatic seabird – the construction of attitudes towards biodiversity management options

Anke Fischer, René van der Wal

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ABSTRACT: Public attitudes towards biodiversity issues and the value judgments underlying biodiversity management and conservation are still poorly understood. This has raised serious concerns regarding the effective use of public participation in biodiversity policy making. We conducted quantitative face-to-face interviews with members of the general public in southeast Scotland to assess attitudes towards biodiversity management and examine attitude formation. For this, we applied social psychological attitude–behaviour theories to a case study investigating biodiversity management options for an island ecosystem in which the abundance of a charismatic seabird, the Atlantic puffin (Fratercula arctica) is compromised by the expansion of a tall invasive plant, tree mallow (Lavatera arborea). We found that attitudes as expressed by members of the public are informed by both value- and knowledge-based elements. Our research provides clear support for the notion that, in a conservation context, value-based principles matter to the public. Out of a set of seven conservation-related values, ‘balance’ and ‘naturalness’ were important factors that related strongly to the respondents’ attitudes. These relationships were even stronger for individuals emotionally involved with the topic. Other value-based principles such as uniqueness, autochthony and endangeredness of the species involved appeared to be of lesser relevance. The findings provide evidence that attitudes can be considered as distinct constructs that offer valuable and meaningful information to biodiversity policymakers and managers, and allow empirical insights into the way value judgments influence biodiversity management and conservation.

Biological Conservation.
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