Bracken fern (Pteridium aquilinum L. kuhn) promotes an open nitrogen cycle in heathland soils
Background and Aims
In spite of the broad array of studies conducted on the ecology of bracken fern (Pteridium aquilinum (L.) kuhn), there is currently only a limited understanding of how P. aquilinum alters the soil environment in which it succeeds. P. aquilinum is one of the world’s most aggressive invasive species and is known to effectively invade conservation priority habitats such as Calluna vulgaris (L.) heathland. The aim of this study was to evaluate differences in soil properties between intact stands of C. vulgaris and neighboring P. aquilinum to assess how P. aquilinum alters soil N transformations in a manner that might promote its success.
Replicate plots in five independently paired stands of P. aquilinum and C. vulgaris were established on land in which P. aquilinum is actively invading. Soils under the two plant types were evaluated for total N, mineralisable N, net nitrification, nitrifier activity, denitrification enzyme activity, polyphenol N complexing capacity, and resin sorption of inorganic N.
Soils under P. aquilinum were consistently higher in NO3- and NH4+ concentrations compared to C. vulgaris. Extractable organic and inorganic N concentrations for soil under P. aquilinum were respectively 65 %, 77 % and 358 % greater in amino N NH4+-N and NO3--N compared to that under C. vulgaris. In-situ net nitrification (NO3- sorption to ionic resins) was found to be nearly 300 times greater under P. aquilinum than under C. vulgaris.
P. aquilinum alters the soil environment as to create an inorganic N-rich environment that is favorable to its growth and development.
KeywordsBelow-ground competition Invasive species Nutrient cycling Nitrogen transformations Shrubland
- Grime JP, Hodgson JG, Hunt R (2007) Comparative plant ecology: a functional approach to common British species. Castlepoint Press, Dalbeattie, UKGoogle Scholar
- Gundale MJ, Sverker J, Albrectsen BR, Nilsson M-C, Wardle DA (2010) Variation in protein complexation capacity among and within six plant species across a boreal forest chronosequence. Plant Soil 211:253–266Google Scholar
- Hart SC, Stark JM, Davidson EA, Firestone MK (1994) Nitrogen mineralization, immobilization, and nitrification. In: Weaver RW, Angle S, Bottomly P (eds) Methods of soil analysis - part 2: microbiological and biochemical properties. Soil Science Society of America, Madison, pp 985–1018Google Scholar
- Jones ME, Fenn ME, Paine TD (2011) The effect of nitrogen additions on bracken fern and its insect herbivores at sites with high and low atmospheric pollution. Arthropod-Plant Inte 5:163–173Google Scholar
- Magesan GN, Wang H, Clinton PW (2012) Nitrogen cycling in gorse-dominated ecosystems in New Zealand. N Z J Ecol 36:21–28Google Scholar
- Marrs RH, Pakeman RJ (1995) Bracken invasion – lessons from the past and prospects for the future. In: Thompson DBA, Hester AJ, Usher MB (eds) Heaths and moorland: cultural landscapes. HMSO, Edinburgh, pp 180–193Google Scholar
- Mulvaney RS (1996) Nitrogen - inorganic forms. In: Sparks DL (ed) Methods of soil analysis. Part 3 - chemical methods. Soil Science Society of America, Madison, pp 1123–1184Google Scholar
- Tiedje JM (1994) Denitrifiers. In: Weaver RW, Angle S, Bottomley P, Bezdicek D, Smith S, Tabatabai A, Wollum A (eds) Methods of soil analysis, Part 2. Microbiological and biochemical processes. Soil Science Society of America, Madison, pp 245–267Google Scholar