Dr. Huei Ying Gan

• Soil biogeochemical and nutrient cycling
• Elemental partitioning and nutrient flows between plants and soil organisms
• Using stable isotopes analysis to determine the trophic connection between above- and belowground organisms
   

Since 01/2022-

Why “Plant-Fog-Oases”?

The Namib desert, a coastal desert along the Atlantic coast of southern Africa, is an important ecosystem where the cold upwelling Benguela current colds the air at the surface of the ocean, resulting in the warm moist air condensing into fog. This frequently formed fog is carried inland which bath the barren desert landscape with moisture, sustaining plants and other fauna with water and nutrients. Over time, plants, and other fauna, undergo adaptations to harvest water from the fog and further modify their environments into mini “oases” comprised of unique trophic interactions. This project looks at such mini oases formed by the Namib dune bushman grass (Stipagrostis sabulicola).

Tasks and objectives

As a soil biogeochemist with prior knowledge in soil elemental cycling, my main interest is to study the nutrient flows between different aboveground (fog, allochthonous deposit, plant biomass) and belowground (soil fauna, soil microorganisms) components, and how the fog interception strategy of the bushman grass fog shapes its soil environment over time.  Eventually, using this information, I also aim to determine the trophic connection between different organisms that thrive in this unique niche.
 

08/2014-09/2019

General information 

The “Biodiversity Exploratories” is a large-scale and interdisciplinary project comprised of more than 250 research members from Germany and Europe. Scientists across different disciplines work together to address crucial questions on how land use and management affect biodiversity and ecosystem functions. The “Exploratories”, as how the study regions are called, comprised of three regions across Germany: Schorfheide-Chorin (Brandenburg), Hainich-Dün (Thuringia) and Schwäbische-Alb (Baden-Württemberg). Different soil properties and climate conditions among these regions also enable researchers to study the complexity of these functions on top of land-use effects. More information can be found at the official website of the project: www.biodiversity-exploratories.de/en/

Tasks and objectives

For my dissertation, I investigated the nutrient flows and stoichiometric interactions in soils under different land uses (forests and grasslands) and managements (e.g., tree species, age group and harvesting in forests and fertilization, mowing, and grazing in grasslands). One of the main questions that I was interested in was, how do land use and management affect the release and amount of plant-available carbon, nitrogen, phosphorus, and sulfur in soils? This question was addressed using the combination of soil incubation and leaching techniques in a controlled environment as well as multivariate statistical analyses. 

Another main question that I was interested in was, how are labile carbon (e.g., freshly decomposed plant detritus and root exudation) partitioned in soils under different land uses? Using stable isotope enrichment techniques, I determined the amount of labile carbon metabolized and released via soil respiration, as well as the amount of native soil carbon released due to increased decomposition via the priming effects. Using the combination of stable isotope probing and molecular techniques, I further investigated the effects of labile carbon on the diversity of soil microorganisms, and whether specific groups of soil microorganisms have a higher affinity for labile carbon assimilations.
 

Gan, H. Y., Schöning, I., Schall, P., Ammer, C., & Schrumpf, M. (2020). Soil organic matter mineralization as driven by nutrient stoichiometry in soils under differently managed forest stands. Frontiers in Forests and Global Change, 3.