Speaker
Description
Increasing nutrient input may have detrimental effects on the biodiversity and ecosystem functioning of grassland ecosystems. However, which mechanisms affect nutrient pools and concentrations at the community level is not always apparent, as an increase in nutrient availability is not necessarily reflected in an increase in biomass and diverse communities often consist of morphologically and physiologically different functional groups.
We studied community aboveground biomass, tissue nutrient concentrations and contents (pools) of functional groups at sites of a globally replicated grassland experiment (Nutrient Network). We analyzed how N (nitrogen), P (phosphorus), and K (potassium) as single nutrients or all possible combinations facilitated variation in nutrient concentrations ([N], [P], [K], carbon [C], calcium [Ca] and magnesium [Mg]) and pools depending on mean annual precipitation (MAP), mean annual temperatures (MAT) and soil acidity (pH). We assessed if observed variation was due to changes in community composition (turnover) caused by nutrient availability or the specific variation in the tissue chemistry of functional groups (graminoids, forbs, legumes, woody species and bryophytes).
Communities with either N or P addition had higher biomass and pools of all nutrients. Singularly, added N increased [N], [K] and [Mg], while P lowered [C], but promoted [P] and [Ca]. K addition led to increased [K] and K content, but decreased [Mg] and [Ca]. Singular effects of nutrient addition mostly outweighed combined effects and combined nutrient effects were additive.
Covariation of turnover and FGV was mostly negative except for [Mg] and [Ca], while variation in nutrient pools was mainly driven by functional group-specific variation (FGV). For most concentrations except [Ca], the effects of turnover and FGV were more balanced. MAT affected functional group-specific variation in [P], K and Ca contents.
Our study highlights the importance of functional group-specific variation of tissue chemistry to nutrient addition and site effects in globally distributed grasslands.
| Status Group | Postdoctoral Researcher |
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