SPP 1685:  Ecosystem Nutrition: Forest Strategies for Limited Phosphorus Resources

• Subject Area: Agriculture, Forestry and Veterinary Medicine
• Term: from 2013 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 220238996

Phosphorus is a limited resource and there is increasing debate regarding the principles of tight P recycling. Forest ecosystems show commonly high P use efficiencies and the processes behind this phenomenon are still unresolved. The members of the priority programme SPP 1685 have applied and refined the concept of ecosystem nutrition, which is based on the integration of results obtained from different spatial and temporal scales and from different disciplines, to unravel these processes. The studies conducted in the first phase, were directed to the identification of processes, interactions and feedbacks associated with the P nutrition of temperate forest ecosystems. We tested the hypothesis that plant and microbial communities established at P rich sites follow a P acquiring strategy introducing P from primary minerals into the biogeochemical P cycle. With decreasing P supply by the parent material, the strategy changes into tight P cycling to sustain the P demand of the forests. The analyses of five beech forest ecosystems on silicate rock representing a P geosequence with different parent materials and thus different total P stocks (160 ¿ 900 g P m-2; down to 1m soil depth) were adjusted to test this hypothesis. These analyses were linked to additional experimental approaches used by individual projects. Spatial scales from micrometers up to the catchment scale and temporal scales from seconds to millions of years have been covered by individual projects. In addition, many methods have been developed or adjusted to the specific requirements related to the challenging analysis of P in forest ecosystems, where P concentrations are in part extremely low. These methodological developments provide promising tools also for ongoing analyses planned for the second phase of the priority programme. Valuable information regarding the P-status of soils and its spatial heterogeneity, the response of plants, plant roots and microbes, and regarding the P fluxes within the ecosystems has been gathered in the first phase of the priority programme. In fact, many of the studies provide evidence for intense P acquiring of beech forests at P- rich sites and tight recycling of P at P- poor sites. Changes in the diversity, activity and spatial distribution soil organisms and in the P-uptake efficiency of plant roots and the transfer of P within plants seem to be the processes behind these different strategies. By using these strategies the organisms change the soil properties, for example the turnover rate of the forest floor, the quality of soil organic matter and the spatial distribution and speciation of P in soils as well as P fluxes. The experience and developments gained from the first phase provide unique opportunities to address still open questions regarding controls and drivers of P strategies, relations between the P dynamics on different temporal and spatial scales or between P and OC dynamics, and human impact on P nutrition.

• DFG Programme: Priority Programmes
• International Connection: Switzerland

Projects

• Arbuscular mycorrhiza along forest soil sequences differing in P-availability (Applicant Rillig, Ph.D., Matthias C. )
• Bioaccessibility and turnover of phosphorous in forest subsoils (Applicants Amelung, Wulf ;  Lewandowski, Hans )
• Coordination-, Network funds- and Workshop module for the priority programme Ecosystem Nutrition: Forest Strategies for limited Phosphorus Resources (Applicant Lang, Friederike )
• Ecosystem nutrition as driver of soil organic matter turnover, a modelling approach (Applicants Schrumpf, Marion ;  Zaehle, Sönke )
• Environmental and intrinsic regulation of phosphorus acquisition, partitioning, storage, and mobilization in beech and poplar trees (Applicant Herschbach, Cornelia )
• Epigenetic adaptation and memory in tree ecosystems (Applicant Ludewig, Uwe )
• Factors controlling phosphorous availability and their relevance for phosphorous nutrition of forest stands (Applicants Bauhus, Jürgen ;  von Wilpert, Klaus )
• Impacts of N/P inputs on organic P dynamics and P status in soils and plants along a nutrient gradient (Applicants Oelmann, Yvonne ;  Pütz, Thomas )
• Interaction between phosphorus heterogeneity patterns in silicate and calcareous soils and root architecture, P nutrition, and growth of European Beech and Norway spruce (Applicant Prietzel, Jörg )
• Isotope geochemical determination of phosphorus weathering sources and fluxes in forest ecosystems (Applicant von Blanckenburg, Friedhelm )
• Linkage between plant sugar and fungal phosphate ex-port in ectomycorrhizal symbiosis (Applicant Nehls, Uwe )
• Linking carbon and nitrogen availability to microbial phosphorous turnover in different forest soils (Applicants Schloter, Michael ;  Schulz, Stefanie )
• Microbial interactions and phosphorus mobilization in forest soils - effects of carbon, nitrogen and phosphorus availability (Applicant Kandeler, Ellen )
• Microbial phosphorus cycling in acquiring and recycling ecosystems (Micro P Cycling) (Applicant Kuzyakov, Yakov )
• Microbial phosphorus cycling in forest soils as dependent on carbon, nitrogen and phosphorus availability (Applicant Spohn, Marie Anneke )
• Nanoparticles and colloids as vectors of P-losses and -redistribution during forest ecosystem development (Applicants Klumpp, Erwin ;  Siemens, Jan )
• PhosForDiv - Phosphate availability as driver of plant biodiversity in forest ecosystems (Applicant Kowarik, Ingo )
• Phosphorus and water flux dynamics in runoff and plant uptake in forested headwaters (Applicant Weiler, Markus )
• Phosphorus concentrations in growth rings of trees as indicators of P availability and recycling efficiency in forest ecosystems (Applicant Bauhus, Jürgen )
• Phosphorus mobilization in acid forest soils as affected by interactions of water regime, fertilization and growth of beech (Applicant Puhlmann, Heike )
• Plant-microbe strategies for utilization of mineral-associated P sources (Applicants Glaser, Bruno ;  Guggenberger, Georg ;  Mikutta, Robert )
• Quantification, modeling, and regionalization of seepage losses of phosphorus from forest soils (Applicants Breuer, Lutz ;  Julich, Dorit )
• Role of inter-specific ectomycorrhizal fungal diversity for forest ecosystem nutrition (Applicant Polle, Andrea )
• Soil microbial necromass as an essential phosphorus reservoir in forest nutrition (Applicant Dippold, Michaela )
• The leak in the phosphorus cycle - exploring the mechanisms and controls of phosphorus leaching in soils of acquiring and recycling forest ecosystems (Applicant Kaiser, Klaus )
• Towards a Molecular Level Understanding of Phosphorous-cycling in Forest Ecosystems (Applicants Ahmed, Ph.D., Ashour ;  Kühn, Oliver )
• Unraveling trees P sources based on the linkage of bottom up und top down approaches for P uptake modelling (Applicant Lang, Friederike )

• Spokesperson: Professorin Dr. Friederike Lang