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• How forest fires and charcoal influence ecosystem processes. This research aims at better understanding the role of wildfire in driving forest succession and in affecting individual species effects and forest productivity in the long term. This work involves the establishment of manipulative and permanent plots along a chronosequence driven by fire history in N Sweden
  
  
• The role of biological N fixation of feather mosses. This work focuses on elucidating mechanisms responsible for determining biological N fixation patterns by cyanobacteria hosted by feather mosses in Boreal forests, and how this N fixation is driven by the structure of the cyanobacterial communities.
  
  
• The effect of secondary metabolites produced by dwarf shrubs (eg. Empetrum hermaphroditum) on ecosystem processes. This research started in the early 1990s and comprises studies ranging from the molecular level to the ecosystem level. This has included studies on the identification of secondary metabolites in plant foliage and litter, the occurrence and stability of these compounds in forest humus, streams and lakes, and their physiological and ecological effects on tree seedling growth.
  
  
• Biodiversity and ecosystem functioning in Boreal forests. This research is aimed at better understanding the consequences of diversity of biotic components of the Boreal forest for ecosystem processes and stability. Some of this research has dealt with the relationships between tree seedling productivity and the diversity of resources, substrate heterogeneity, ectomycorrhizae and the soil microbial community.
  
  
• Forest stand dynamics in non-pyrogenic Boreal forests. This work investigates the influence of previous climatic fluctuations on the natural regeneration of virgin Scots pine populations in N Sweden and highlights the role of understory vegetation in driving stand dynamics under climate change.
  
  
• Effects of silvicultural practices on early tree seedling performance. This work focuses on using steam as an alternative to soil scarification for ground layer vegetation control on forest clear-cuts. It shows that steam controls ground layer vegetation and encourages better growth of Scots pine and associated mycorrhizal fungi when compared with traditional soil scarification and prescribed burning methods.
  
  
• The role of ecological stresses on aboveground and belowground subalpine communities. This research is performed in experimental plots that have been running since 1986, and is aimed at exploring how ecological stresses affect the belowground community through promoting domination of slow-growing ericaceous dwarf shrubs at the expense of fast-growing graminoid species.

The role of understory on ecosystem processes - overview articles:

How forest fires and charcoal influence ecosystem processes:
Wardle DA, Nilsson M-C, and Zackrisson O. 2008. Fire-derived charcoal causes loss of forest humus. Science 320: 629-629.

Keech O, Carcaillet C, and Nilsson M-C. 2005. Adsorption of allelopathic compounds by wood-derived charcoal: the role of wood porosity. Plant and Soil 272: 291-300.

DeLuca TH, Nilsson M-C, and Zackrisson O. 2002. Nitrogen mineralization and phenol accumulation along a fire chronosequence in northern Sweden. Oecologia 133: 206-214.

Wardle DA, Zackrisson O, and Nilsson M-C. 1998. The charcoal effect in Boreal forests: mechanisms and ecological consequences. Oecologia 115: 419-426.

Zackrisson O, Nilsson M-C, and Wardle DA. 1996. Key ecological function of charcoal from wildfire in the Boreal forest. Oikos 77: 10-19.

Nilsson M-C. 1994. Separation of allelopathy and resource competition by the Boreal dwarf shrub Empetrum hermaphroditumOecologia Hagerup. 98: 1-7.

The role of biological N fixation of feather mosses:

Gundale MJ, Wardle DA and Nilsson M-C. 2010 Vascular plant removal effects on biological N-fixation vary across a boreal forest island gradient. Ecology (in press).

Gundale MJ, Gustafsson H and Nilsson M-C 2009 The sensitivity of N-fixation by a cyanobacteria-feathermoss association to litter and moisture variability in young and old boreal forests.  Canadian Journal of Forest Research 39:2542-2549.

DeLuca TH, Zackrisson O, Gundale M and M-C Nilsson. 2008. Ecosystem feedbacks and nitrogen fixation in boreal forests Science 320: 1181-1181.

Lagerström, A, Nilsson M-C, Zackrisson O et al. 2007. Ecosystem input of nitrogen through biological fixation in feather mosses during ecosystem retrogression. Functional Ecology 21: 1027-1033.

DeLuca TH, Zackrisson O, Gentili F, et al. 2007. Ecosystem controls on nitrogen fixation in Boreal feather moss communities. Oecologia 152: 121-130.

Zackrisson O, DeLuca TH, Nilsson M-C, et al. 2004. Nitrogen-fixation increases with successional age in boreal forests. Ecology 85: 3327-3334.

DeLuca TH, Zackrisson O, Nilsson M-C et al. 2002. Quantifying nitrogen-fixation in feather moss carpets of boreal forests. Nature 419: 917-920.

The role of ecological stresses on aboveground and belowground subalpine communities:
Shevtsova A, Nilsson M-C, Gallet C, et al. 2005. Effects of long-term alleviation of nutrient limitation on shoot growth and foliar phenolics of Empetrum hermaphroditum. Oikos 111: 445-458.

Nilsson M-C, Wardle DA, Zackrisson O, and Jäderlund A. 2002. Effects of alleviation of ecological stresses on an alpine tundra community over an eight year period. Oikos 97: 3-17.

The role of secondary metabolites produced by dwarf shrubs (eg. Empetrum hermaphroditum) for ecosystem processes:
Wallstedt A, Gallet C, and Nilsson M-C. 2005. Behaviour and recovery of the secondary metabolite Batatasin-III from boreal forest humus: influence of temperature, humus type and microbial community. Biochemical Systematics and Ecology 33: 385-407.

Brännäs, E, Nilsson M-C, Nilsson L, et al. 2004. Potential toxic effect on aquatic fauna by the dwarf shrub Empetrum hermaphroditum. Journal of Chemical Ecology 30: 215-227.

Wallstedt A, Sommarin M, Nilsson M-C, et al. 2001. The inhibition of ammonium uptake in excised birch (Betula pendula) roots by Batatasin-III. Physiologia Plantarum 113: 368-376.

Wallstedt A, Nilsson M-C, Zackrisson O, and Odham G. 2000. A link in the study of chemical interference exerted by Empetrum hermaphroditum: Quantification of batatasin-III in soil solution. Journal of Chemical Ecology 26: 1311-1323.

Nilsson M-C, Zackrisson O, Sterner O, and Wallstedt A. 2000. Characterisation of the differential interference effects of two boreal dwarf shrub species. Oecologia 123: 122-128.

Gallet C, Nilsson M-C, and Zackrisson O. 1999. Phenolic metabolites of ecological significance in Empetrum hermaphroditum leaves and associated humus. Plant and Soil 210: 1-9.

Nilsson M-C, Gallet C, and Wallstedt A. 1998. Temporal variability of phenolics and batatasin-III in Empetrum hermaphroditum leaves over an eight-year period: interpretations of ecological function. Oikos 81: 6-16.

Nilsson M-C. 1994. Separation of allelopathy and resource competition by the Boreal dwarf shrub Empetrum hermaphroditum Oecologia Hagerup. 98: 1-7.

Nilsson M-C, Högberg P, Zackrisson O, and Wang FY. 1993. Allelopathic effects by Empetrum hermaphroditum on development and nitrogen uptake by roots and mycorrhizae of Pinus silvestris. Canadian Journal of Botany 71: 620-628.

Odén PC, Brandtberg PO, Andersson R, et al. 1992. Isolation and characterization of a germination inhibitor from leaves of Empetrum hemaphroditum Hagerup. Scandinavian Journal of Forest Research 7: 497-502.

Zackrisson O and Nilsson M-C. 1992. Allelopathic effects by Empetrum hermaphroditum on seed-germination of 2 Boreal tree species. Canadian Journal of Forest Research 22: 1310-1319.

Nilsson M-C and Zackrisson O. 1992. Inhibition of Scots pine seedling establishment by Empetrum hermaphroditum. Journal of Chemical Ecology 18: 1857-1870.

Biodiversity and ecosystem functioning in Boreal forests:
Wardle DA, Lagerström A, and M-C Nilsson. 2008. Context dependent effects of plant species and functional group loss on vegetation invasibility across an island area gradient. Journal of Ecology 96: 1174-1186.

Nilsson M-C, Wardle DA, and DeLuca TH. 2007. Belowground and above ground consequences of interactions between live plant species mixtures and dead organic substrate mixtures. Oikos 117: 439-449

Dehlin H, Nilsson M-C, and Wardle DA. 2006. Aboveground and belowground responses to quality and heterogeneity of organic inputs to the boreal forest. Oecologia 150: 108-118.

Jonsson LM, Nilsson M-C, Wardle DA, and Zackrisson O. 2001. Context dependent effects of ectomycorrhizal species richness on tree seedling productivity. Oikos 93: 353-364.

Nilsson M-C, Wardle DA, and Dahlberg A. 1999. Effects of plant litter species composition and diversity on the boreal forest plant-soil system. Oikos 86: 16-26.

Forest stand dynamics in non-pyrogenic Boreal forests:
Zackrisson O, Nilsson M-C, Jäderlund A, and Wardle DA. 1999. Nutritional effects of seed fall during mast years in boreal forest. Oikos 84: 17-26.

Steijlen I, Nilsson M-C, and Zackrisson O. 1995. Seed regeneration of Scots pine in Boreal forest stands dominated by lichen and feather moss. Canadian Journal of Forest Research 25: 713-723.

Zackrisson O, Nilsson M-C, Steijlen I, and Hörnberg G. 1995. Regeneration pulses and climate vegetation interactions in nonpyrogenic Boreal Scots pine stands. Journal of Ecology 83: 469-483.

Effects of silvicultural practices on early tree seedling performance:
Dehlin, H, Nilsson M-C, Wardle DA, et al. 2004. Effects of shading and humus fertility on growth, competition and ectomycorrhizal colonisation of boreal forest tree seedlings. Canadian Journal of Forest Research 34: 2573-2586.

Norberg G, Dolling A, Jäderlund A, et al. 2001. Control of heather (Calluna vulgaris (L.) Hull) by steam treatment: Effects on establishment and early growth of Scots pine. New Forests 21: 187-198.

Jäderlund A, Norberg G, Zackrisson O, et al. 1998. Control of bilberry vegetation by steam treatment - effects on seeded Scots pine and associated mycorrhizal fungi. Forest Ecology and Management 108: 275-285.

Norberg G, Jaderlund A, Zackrisson O, et al. 1997. Vegetation control by steam treatment in boreal forests: a comparison with burning and soil scarification. Canadian Journal of Forest Research 27: 2026-2033.

Nilsson M-C, Steijlen I, and Zackrisson O. 1996. Time-restricted seed regeneration of Scots pine in sites dominated by feather moss after clear-cutting. Canadian Journal of Forest Research 26: 945-953.

Recent services

• Member of the National Research Agenda (NRA) Counsel Board (2008- present)
• Substitute member at the Scientific Board of the Swedish Research Council FORMAS (2007-2009).
• Chairman for the Committee ‘Kempe Award for Distinguished Ecologists' (2007-2008; and member of the Committee since 1999).
• Member of the Executive Board of the Department of Forest Ecology and Management (2007- present).
• Chairman for the ‘Erik Rönnberg Fund' (2008-present).
• Member of the Board of the Fund for Forest Science at the Swedish University of Agricultural Sciences (2003-2006).
• Deputy Dean and Vice Chairman of the Faculty Board (2003-2006).
• Member of the Scientific Advisory Panel for the research programme FINITE funded by the American Chemistry Council at the Centre for Ecology and Hydrology (CEH) at Lancaster, U.K. (2002-2006).
• Head of the Department of Forest Vegetation Ecology (1999-2003).
• Member of University Reference Group to develop a program aimed at improving the quality of research and education within SLU (1999 and 2004).
• Regular external reviewer for funding proposals, and external evaluator in the recruitment process of full, associate and assistant professors in several Nordic countries.

• Till Jochum (started 2009) Project title: Forest regeneration of broadleaved trees in N Sweden.
• Guillaume Bay (started 2008) Project title: Role of biodiversity of nitrogen fixing cyanobacteria in feather mosses on nitrogen input to boreal forest ecosystems.
• Benjamin Jackson (started 2007; D. Wardle as main supervisor) Project title: Regulation of litter decomposition and nutrient availability in Swedish and New Zealand forests
• Anna Lagerström (started 2004) Project title: Stoichiometric Controls of Ecosystem Processes Above and Below Ground in Forests of Northern Sweden and New Zealand.
• Helena Dehlin (completed 2006)
• Linda Berglund (completed 2004; T.H. DeLuca as main supervisor)
• Anders Jäderlund (completed 2001)
• Gisela Norberg (completed 2001: O. Zackrisson as main supervisor)
• Anna Wallstedt (completed1998)

Supervision of MSc-students:

• Helena Gustafsson, SLU (2008) Thesis title: The effect of moisture, litter and stand age on N fixation in the feathermoss Pleurozium schreberi.
• Pablo Martin Ortega Erasmus-Mundus Student, Spain (2008) Thesis title: Water availability controls nitrogen fixation in the feather moss Pleurozium schreberi.
• Valerie Kurth, Fulbright Student, USA (2005-2006)
• Dolores Baamonde, Spain (2004)
• Björn Eriksson, SLU (2003)
• Olivier Keech, exchange student, France (2003)
• Helena Dehlin, SLU (2001)

Post-doctoral researchers that have worked in my group:

• Sheel Bansal (2009-  )
• Tuula Puhakainen, Finland (2005-2008)
• Genevieve Chiapusio, France (2004)
• Vera Thoss, United Kingdom (2001)
• Anna Shevtsova, Finland (1999-2000)
• Anna Wallstedt, Lund University (1999-2000)
• Lena Jonsson, SLU Uppsala (1999)