Ecological stoichiometry, atmospheric N deposition and soil C : N ratios in Europe

Size: px

Start display at page:

Download "Ecological stoichiometry, atmospheric N deposition and soil C : N ratios in Europe"

Melina Hunt
5 years ago
Views:

1 Ecological stoichiometry, atmospheric N deposition and soil C : N ratios in Europe Christian Mulder, Luca Montanarella, and Rannveig Anne Guicharnaud

2 Nutrient cycling is closely related to the elemental composition of living biomass (Elser, 2006).

3 Nutrient cycling is closely related to the elemental composition of living biomass (Elser, 2006). Identification of empirical soil C : N ratios that are critical for life-supporting functions is challenging, surely at continental scale.

4 Nutrient cycling is closely related to the elemental composition of living biomass (Elser, 2006). Identification of empirical soil C : N ratios that are critical for life-supporting functions is challenging, surely at continental scale. A correlation between atmospheric N and the soil C : N would be a constraint which affects the productivity of ecosystems.

5 The relevancy of soil C : N ratio as proxy forecasting soil fertility is well documented (e.g., Gundersen 1991, Wardle 2002, etc.) LUCAS 2009

6 Why Should Soil C : N Be Relevant? (1) All organisms can be correlated with their environment based on eco-stoichiometric relationships, both in the organism as in its environment (organism and resource stoichiometry, respectively).

7 Why Should Soil C : N Be Relevant? (2) If the organism stoichiometry DOES NOT reflect the resource stoichiometry, the organism (hence, the taxon) has to be regarded as HOMEOSTATIC. Alternatively, the organism stoichiometry DOES reflect the resource stoichiometry, the organism (hence, the taxon) has to be regarded as NON HOMEOSTATIC. Non-homeostatic taxa react to changes in C, N, and P. This makes C : N relevant.

8 Sterner and Elser (2002); Cleveland and Liptzin (2007)

9 How Relevant is Soil N for Growth? Vrede et al. (2004) pointed out that better correlations for plants are found between increased growth and a decreased C : N (carbohydrate : protein) ratio than a decreased N : P (protein : RNA) ratio. If so, given the non-homeostatic nature of plants, changes in resource C : N are expected to be reflected in changes in their organism C : N (like foliar tissues), with cascading effects across trophic levels.

10 Leaf δ 15 N : Leaf δ 15 N Soil δ 15 N (Δ 15 N) Data: TRY, Paper: Mulder et al. (2013)

11 Is Nitrogen Eutrophication Dangerous? Microarthropods 1:1 Log [nutrient] organism Nematodes Log [nutrient] ecosystem Mulder and Elser (2009), Sardans and Peñuelas (2012), Mulder et al. (2013)

12 Airborne N changes heathlands into grasslands, affecting historically important ecosystems and threatening ecosystem services like pollination

14 Soil C : N ratios Serie y = 145.6x -0. R² = N Eutrophication pdf(c -λ soil : Nsoil) [Nair ] Mean atmospheric N deposition

15 Air N Threatens Ecosystem Services (1) Cleveland and Liptzin (2007) recorded fluctuating soil C : N ratios, but overall their soil C : N ratio approaches 14.3

16 Air N Threatens Ecosystem Services (2) Cleveland and Liptzin (2007) recorded fluctuating soil C : N ratios, but overall their soil C : N ratio approaches 14.3 This C : N value is remarkably close to the inflection ( rate of change ) of the negative power fit of the previous slide

17 Air N Threatens Ecosystem Services (3) Cleveland and Liptzin (2007) recorded fluctuating soil C : N ratios, but overall their soil C : N ratio approaches 14.3 This C : N value is remarkably close to the inflection ( rate of change ) of the negative power fit of the previous slide The model allows to ascribe sites (and their ecosystem services) to an ongoing N eutrophication according to the inflection

19 Take-Home Message We evaluated the most recent continental soil survey (LUCAS 2009)

20 Take-Home Message We evaluated the most recent continental soil survey (LUCAS 2009) We verified the correlation of soil C : N with N deposition over the last decade

21 Take-Home Message We evaluated the most recent continental soil survey (LUCAS 2009) We verified the correlation of soil C : N with N deposition over the last decade We aim to define in the near future the critical elemental thresholds for plants, bacteria, fungi and soil invertebrates

Key Concepts 1. What different levels of organization do ecologists study? 2. What methods are used to study ecology?

Key Concepts 1. What different levels of organization do ecologists study? 2. What methods are used to study ecology? Chapter 3 The Biosphere 3 1 What is Ecology? 1. What different levels of organization do ecologists study? 2. What methods are used to study ecology? Ecology study of interactions between organisms and