Abstract
Changes in land use may lead to increased soil nutrient levels in many ecosystems (e.g. due to intensification of agricultural fertilizer use). Plant species differ widely in their response to differences in soil nutrients, and for savannas it is uncertain how
this nutrient enrichment will affect plant community dynamics. We set up a large controlled short-term experiment in a semi-arid savanna to test how water supply (even water supply vs. natural rainfall) and nutrient availability (no fertilisation
vs. fertilisation) affects seedlings’ above-ground biomass production and leaf-nutrient concentrations (N, P and K) of broadleafed and fine-leafed tree species. Contrary to expectations, neither changes in water supply nor changes in soil nutrient
level affected biomass production of the studied species. By contrast, leaf-nutrient concentration did change significantly.
Under regular water supply, soil nutrient addition increased the leaf phosphorus concentration of both fine-leafed and
broad-leafed species. However, under uneven water supply, leaf nitrogen and phosphorus concentration declined with soil
nutrient supply, this effect being more accentuated in broad-leafed species. Leaf potassium concentration of broad-leafed
species was lower when growing under constant water supply, especially when no NPK fertilizer was applied. We found that
changes in environmental factors can affect leaf quality, indicating a potential interactive effect between land-use changes
and environmental changes on savanna vegetation: under more uneven rainfall patterns within the growing season, leaf
quality of tree seedlings for a number of species can change as a response to changes in nutrient levels, even if overall plant
biomass does not change. Such changes might affect herbivore pressure on trees and thus savanna plant community
dynamics. Although longer term experiments would be essential to test such potential effects of eutrophication via changes
in leaf nutrient concentration, our findings provide important insights that can help guide management plans that aim to
preserve savanna biodiversity.
Original language | English |
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Article number | e92619 |
Number of pages | 9 |
Journal | PLoS ONE |
Volume | 9 |
Issue number | 3 |
DOIs | |
Publication status | Published - 2014 |
Keywords
- semiarid savannas
- mineral-nutrition
- african savannas
- large herbivores
- nitrogen
- plants
- carbon
- fire
- phosphorus
- responses