Hawkesbury Institute for the Environment

• Awards and Recognition
• Selected Publications
• Contact (opens in a new window) 

Uffe joined HIE in 2011 from the Department of Biology and Natural Resource Ecology Laboratory, Colorado State University, USA, where he worked as a Research Scientist with Professor Diana H. Wall.
Uffe received his PhD in 2008 from University of Aberdeen, Scotland, in close collaboration with the Macaulay Institute (now the James Hutton Institute) and Center of Hydrology and Biology (CEH). His PhD research focused on the distribution and community composition of soil biota (microbes and soil mites in particular) across various spatial scales in two contrasting habitats. This research mainly targeted the questions of what structures belowground communities and how belowground communities respond to environment parameters and environmental changes (such as land use and climate). Through his research at CSU Uffe continued investigating patterns of, and mechanisms underlying, biodiversity and community composition belowground, whilst also trying to establish and quantify potential links between soil biodiversity and belowground community composition and ecosystem processes/functioning and ecosystem services. His position here also allowed him to expanded his research to include a more broad range of soil biota and explore the flow of C and N through the soil food web using stable isotope techniques.

Areas of Research / Teaching Expertise

Uffe is broadly interested in community and ecosystem ecology, and the link between the two, i.e. how do changes in one influence the other. In a time where large-scale changes in land use and climate are impacting ecosystems across the globe it is essential for human well-being to acquire knowledge of the potential implications of these changes. For instance, species gains and losses, and changes in community composition, belowground due to climate changes can impact nutrient cycling, which may lead to changes in aboveground communities and potentially limit productivity of agricultural lands. Other research areas of interest to Uffe include large-scale ecological theories, whether ecological theories hold across ecosystem types (including soils) and scales, drivers of species richness and biogeography (of soil biota in particular) etc. Over the past few years Uffe has used the biologically simple soils of the McMurdo Dry Valleys, East Antarctica, to explore these aspects of ecology. While he will continue his Antarctic research through collaboration with the Australian Antarctic Division as well as the USA McMurdo Long Term Ecological Research program he will explore whether the hypotheses gained through this research are applicable in more biologically complex systems.

Motivated students are encouraged to contact Dr Nielsen to discuss potential undergraduate and graduate research projects broadly related to soil ecology and above-belowground interactions.

Awards and Recognition

• Section editor for Nature Knowledge (Community Ecology) (opens in a new window);
• Subject editor for Ecosphere (opens in a new window); 
• Reviewer for several international journals including: Biology Letters; Ecosystems; Global Change Biology; Nature Knowledge; Oecologia; Plant and Soil; PLoS ONE; Soil Biology & Biochemistry

Selected Research Images

Soils are highly diverse systems. All the fauna shown here was extracted using Tullgren funnels (dry extraction) from a single soil core collected in a birch woodland, Scotland, measuring 3.5 cm diameter and 5 cm depth. This method only samples the fauna that live in the airfilled pores within the soil also known as microarthropods. It is not unusual to find several hundreds of thousands individuals representing hundreds of species in one m² soil. If we used a different wet extraction method the soils would reveal a further astonishing diversity of mesofauna dominated by the nematodes (with abundances measured in the millions per m²). All these organisms combined have a large impact on the soil food web, and they represent a multitude of life styles ranging from plant parasites to predators. While our knowledge of these organisms is accumulating we still need a better understanding of how they influence key processes, such as decomposition and the release of nutrients for plants, and how the communities will respond to land management and potential climate change scenarios to better protect and conserve the benefits we receive from soils.

Project Bluestem at the Konza Long-Term Ecological Research site, Kansas, USA. This project uses dual stable isotope (¹³C and ¹⁵N) labelled big bluestem litter to investigate how carbon and nitrogen flows through the soil food web and how large a role soil fauna play in the decomposition process. Dr. Nielsen is a collaborator on the project with the principal investigator, Prof Francesca Cotrufo, and the co-investigators, Profs Diana Wall and Bill Parton, all based at Natural Resource Ecology Lab at Colorado State University.

Taylor Valley, McMurdo Dry Valleys, East Antarctica. While a large part of Antarctica is ice or snow covered some areas, like the McMurdo Dry Valleys, are ice and snow free all year round. The soils found here are very low in organic matter and highly saline, and available water is limited to a short period of time during the summer. Only a few species of higher soil fauna (including nematodes, rotifers and tardigrades) are capable of surviving these conditions. However, the simplicity of the communities and potential climate change impacts makes it a highly valuable system to research. Key areas of research include the study of the biogeography of soil fauna throughout the McMurdo Dry Valleys (i.e. why are the animals where they are) and how will the system might respond to climate changes (both gradual and extreme events).

Selected Publications

Book Chapters
Nielsen UN, Wall DH, (2010) 'Soil biodiversity in extreme soil environments', In: Jeffery, S. et al (Eds). European Atlas of Soil Biodiversity. European Commission, Publications Office of the European Union, Luxemburg. Chapter 3, section 7, pp 32-35

Wall DH, Nielsen UN, (2009) 'The Substrate of Life - Soils', In: The Wealth of Nature – Ecosystem Services, Biodiversity and Human Well-being. McNeely, JA. et al. (Eds). Conservation International. Washington, DC

Riis T, Brix H, Nielsen UN, (2008) 'Luronium natans in River Skjern, Denmark', In: Skjern å. Nielsen, I. et al. (Eds.) pp 185-200. In Danish.

Nielsen UN, (2005) 'Current distribution of Luronium natans in Denmark, URT (Danish botanical journal). In Danish.

Journal Articles

Nielsen UN, Wall DH, (2013) 'The future of soil invertebrate communities in polar regions: Different climate change responses in the Arctic and Antarctic?' Ecology Letters, vol.16, no.3, pp 409-419

Fierer N, Leff JW, Adams BJ, Nielsen UN, Bates ST, Lauber CL, Owens S, Gilbert JA, Wall DH, Caporaso JG, (2012) 'Cross-biome metagenomic analyses of soil microbial communities and their functional attributes', Proceedings of the National Academy of Sciences of the United States of America, vol.109, no.52, pp 21390-21395

Johnson SN, Nielsen UN, (2012) 'Foraging in the Dark - Chemically Mediated Host Plant Location by Belowground Insect Herbivores', Journal of Chemical Ecology, vol.38, no.6, pp 604-614

Nielsen UN, Osler GHR, Campbell CD, Burslem DFRP, van der Wal R, (2012) 'Predictors of fine-scale spatial variation in soil mite and microbe community composition differ between biotic groups and habitats', Pedobiologia, vol.55, no.2, pp 83-91

Nielsen UN, Wall DH, Adams BJ, Virginia RA, Ball BA, Gooseff MN, McKnight DM, (2012) 'The ecology of pulse events: insights from an extreme climatic event in a polar desert ecosystem', Ecosphere, vol.3, no.2, Article 17

Smith TE, Wall DH, Hogg ID, Adams BJ, Nielsen UN, Virginia RA, (2012) 'Thawing permafrost alters nematode populations and soil habitat characteristics in an Antarctic polar desert ecosystem',  Pedobiologia, vol.55, no.2, pp 75-81

Stanish LF, Kohler TJ, Esposito RMM, Simmons BL, Nielsen UN, Wall DW, Nemergut DR, McKnight DM, (2012) 'Extreme streams: flow intermittency as a control on diatom communities in meltwater streams in the McMurdo Dry Valleys, Antarctica', Canadian Journal of Fisheries and Aquatic Sciences, vol.69, no.8, pp 1405-1419

Wall DH, Nielsen UN, (2012) 'Biodiversity and ecosystem services; is it the same belowground?', Nature Education Knowledge, vol.3, no.12, p 8

Nielsen UN, Ayres E, Wall DH, Bardgett RD, (2011) 'Soil biodiversity and carbon cycling: a synthesis of studies examining diversity-function relationships', European Journal of Soil Science, vol.62, no.1, pp 105-116

Nielsen UN, Wall DH, Adams BJ, Virginia RA, (2011) 'Antarctic nematode communities: observed and predicted responses to climate change', Polar Biology, vol.34, no.11, pp 1701-1711  

Nielsen UN, Wall DH, Toro M, Adams BJ, Virginia RA, (2011) 'Nematode communities of Byers Peninsula, Livingston Island, maritime Antarctica', Antarctic Science, vol.23, no.4, pp 349-357, doi:10.1017/S0954102011000174

Nielsen UN, Osler GHR, Campbell CD, Neilson R, Burslem DFRP, Van der Wal R, (2010) 'The enigma of soil animal species diversity revisited: the role of small-scale heterogeneity', PLoS ONE 5(7): e11567. doi:10.1371/journal.pone.0011567

Nielsen UN, Osler GHR, Campbell CD, Burslem DFRP, Van der Wal R, (2010) 'The influence of vegetation type, soil properties and precipitation on the composition of soil mite and microbial communities at the landscape scale', Journal of Biogeography, vol.37, no.7, pp 1317-1328

Nielsen UN, Osler GHR, Van der Wal R, Campbell CD, Burslem DFRP, (2008) 'Soil pore volume and the abundance of soil mites in two contrasting habitats', Soil Biology & Biochemistry, vol.40, no.6, pp 1538-1541

Nielsen UN, Riis T, Brix H, (2006) 'The effect of weed cutting on Luronium natans', Aquatic Conservation-Marine and Freshwater Ecosystems, vol.16, no.1, pp 409-417

Nielsen UN, Riis T, Brix H, (2006) 'The importance of vegetative and sexual dispersal of Luronium Natans', Aquatic Botany, vol.84, no.2, pp 165-170

Conference Proceeding

Levy J, Fountain A, Gooseff MN, Barrett JE, Wall DN, Nielsen UN, Adams BJ, Lyons WB, (2012) 'Active Layer Processes in the McMurdo Dry Valleys, Antarctica: Decadal Trends and Experimental Responses to Changes in Soil Moisture' In: Hinkel, K.M. (ed.). Tenth International Conference on Permafrost. Vol. 1: International Contributions. The Northern Publisher, Salekhard, Russia, pages 221-226.