Spatial distributions of plants and gross N transformation rates in a forest soil
- Biologiska institutionen
- Microbial Ecology
2 A geostatistical analysis was used to evaluate the spatial relationships between abundance and species composition of the understorey vegetation and in situ gross N mineralization, NH4+ immobolization and nitrification rates.
3 The gross N transformation rates and the plants spatial variation were correlated within the forest, but plant distribution was more dependent on the fraction of mineralized N that was nitrified than on individual N transformation rates.
4 The total cover of the understorey vegetation varied more in space than the species composition, and was higher in areas with high N transformation rates.
5 Plant species benefiting from high net nitrification rates were more common in areas with a low activity of mineralizing and nitrifying microorganisms, possibly because the net and gross rates were independent of each other. In fact, those species occurred most often in areas in which a large fraction of mineralized N was nitrified.
6 Beech and oak trees also had an effect on the spatial variation of the understorey vegetation. Beech trees provided conditions more suitable for plants benefiting from NO3-, whereas the vascular plant cover was greater under oak trees, probably in response to a higher light interception than under beech trees.
7 Oak generally had a positive impact on gross N transformation rates compared with beech, perhaps reflecting differences in litter quality and climate caused by the two species.
8 The influence of trees alone could not explain the full magnitude of the variation of N transformation rates or the presence of overlapping areas with high mineralization and immobilization rates. These were probably caused by other factors, such as soil moisture content.
9 This work sheds new light on the small-scale spatial links between above-ground plant diversity and abundance, and below-ground microbial N transformations.
- Biological Sciences
- Microbial Ecology
- ISSN: 1365-2745