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Results of the preceding DYNPHOS phase showed that increasing plant diversity decreased plant- available P concentrations in soil through increasing P exploitation at the Swabian Alb. It remains unclear if combined effects of land-use intensity and plant diversity on P transformation processes in soil will result in tight ecosystems P cycling and thus, requiring less fertilizer P while maintaining productivity.


The objective is to differentiate the effect of land-use intensity (LUI) and plant diversity on

  1. gross P mineralization,
  2. microbial biomass P, and
  3. dissolved P leaching (PO4-P and DOP)

in soil of all grassland and forest plots of the three Exploratories (n = 300).


LUI has contrasting implications for P cycling in forests and grasslands i. e., high removal of P in forests versus high input of P in grasslands under high land-use intensity. Therefore, hypotheses are postulated specifically for forests and grasslands. The following hypotheses will be tested.

Forests:

1a. Increasing LUI decreases tree growth, foliar P concentrations, and root exudation. Therefore, gross P mineralization rates are negatively correlated with LUI.

1b. Increasing plant diversity results in balanced microclimate and increased decomposition-substrate diversity and thus, accelerated microbial activity. Therefore, gross P mineralization is positively related to plant diversity under comparable LUI.

 2a. Increasing LUI increases biomass removal and thus, reduces root mass and root exudation in soil. Therefore, microbial biomass P decreases with increasing LUI.

2b. Plant diversity increases gross P mineralization and thus, microbial biomass. Therefore, plant diversity increases microbial biomass P under comparable LUI.

3a. Increasing LUI decreases P supply in soil and thus, decreases PO4-P and DOP leaching.

 3b. Because of increased plant P uptake and increased microbial biomass P, plant diversity is negatively related to PO4-P and DOP leaching under comparable LUI.

Grasslands:

1c. Increasing LUI increases N (and P) input into soil thus, decreasing root mass and root exudation. These decreases microbial activity and thus, gross P mineralization rates.

1d. Under comparable LUI, positive effects of microclimate and decomposition-substrate diversity result in increased gross P mineralization rates in highly diverse ecosystems.

 2c. The increased N (and P) input in case of high LUI results in decreased microbial biomass, Therefore, increasing LUI decreases microbial biomass P.

2d. Under comparable LUI, increased gross mineralization rates in highly diverse ecosystems are related to increased microbial biomass. Therefore plant diversity increases microbial biomass.

 3c. Because of increased P input and decreased microbial biomass P, LUI increases PO4-P and DOP leaching.

3d. Under comparable LUI, plant diversity leads to decreased PO4-P and DOP leaching because of increased plant uptake and microbial biomass P.

Therefore, we expect that plant diversity reduces P leaching under high LUI in grassland and we will focus on the relationship between biodiversity and the P cycle in soil accounting for management, site conditions and historic land-use of the studied plots.


Doc
The Phosphorus Cycle in Grassland and Forest Ecosystems of different Biodiversity and Management
Alt F. (2013): The Phosphorus Cycle in Grassland and Forest Ecosystems of different Biodiversity and Management. Dissertation, University Tübingen.
Doc
Wie viel Phosphor wird in Grünland- und Waldböden freigesetzt?
Alt F., Oelmann Y., Schöning I., Wilcke W. (2013): Phosphate release kinetics in calcareous grassland and forest soils in response to H+ addition. Soil Science Society of America Journal 77 (6), 2060-2070. doi: 10.2136/sssaj2013.02.0072
More information:  doi.org
Doc
Phosphor-Partitionierung in deutschen Grünland-und Waldböden in Bezug auf Landnutzungstyp, Bewirtschaftungsintensität und landnutzungsbedingtem pH-Wert.
Alt, F., Oelmann, Y., Herold, N., Schrumpf, M., Wilcke, W. (2011): Phosphorus partitioning in German grassland and forest soils as related to land-use type, management intensity, and land-use related pH. Journal of Plant Nutrition and Soil Science 174 (2), 195-209. doi: 10.1002/jpln.201000142
More information:  doi.org
Doc
Landnutzungs- und Biodviersitätseffekte auf P-Transformationen im Boden
Sorkau E. (2018): Land use and biodiversity effects on P-transformation in soil. Dissertation, University Tübingen
Doc
Die Rolle von Bodeneigenschaften, Landnutzung und Pflanzenartenvielfalt für den mikrobiellen Phosphor im Boden
Sorkau E., Boch S., Boeddinghaus R., Bonkowski M., Fischer M., Kandeler E., Klaus V., Kleinebecker T., Marhan S., Müller J., Prati D., Schöning I., Schrumpf M., Weinert J., Oelmann Y. (2018): The role of soil chemical properties, land use and plant diversity for microbial phosphorus in forest and grassland soils. Journal of Plant Nutrition and Soil Science 181 (2), 185-197. doi: 10.1002/jpln.201700082
More information:  doi.org
Doc
Phosphorus budget of German grasslands – effects of management and relation to biodiversity
Traub K. (2016): Phosphorus budget of German grasslands - effects of management and relation to biodiversity. Master thesis, University Tübingen
Doc
Effects of plant species richness on plant-available nitrogen and phosphorus concentrations in soils under grasslands of the Schwäbische Alb differing in land-use intensity
Wahl A. S. (2012): Effects of plant species richness on plant-available nitrogen and phosphorus concentrations in soils under grasslands of the Schwäbische Alb differing in land-use intensity. Thesis, University Tuebingen

Project in other funding periods

DYNPHOS I (Contributing project)
#Soil biology & Element Cycling  #2008 – 2011  

Scientific assistants

Prof. Dr. Yvonne Oelmann
Project manager
Prof. Dr. Yvonne Oelmann
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