Institut für Bodenkunde und Standortslehre

Permanent URI for this collectionhttps://hohpublica.uni-hohenheim.de/handle/123456789/10

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Distribution of Al, Fe, Si, and DOC between size fractions mobilised from topsoil horizons with progressing degree of podzolisation
(2022) Krettek, Agnes; Stein, Mathias; Rennert, Thilo
Aluminium, Fe, Si, and dissolved organic C (DOC) accumulate in the subsoil of Podzols after mobilisation in the topsoil. We conducted laboratory experiments with topsoil horizons with progressing degree of podzolisation by irrigation with artificial rainwater at varying intensity and permanence. We monitored the concentrations and distribution of mobilised Al, Fe, Si, and DOC between size fractions (< 1000 Dalton, 1 kDa– < 0.45 µm, and > 0.45 µm). Total eluate concentrations were increased at the onset of the experiments and after the first irrigation interruption, indicating non-equilibrium release. There was no statistical effect of the degree of podzolisation on element concentrations. Release of Al, Fe, and DOC was mostly dominant in the fraction 1 kDa– < 0.45 µm, indicating metals complexed by larger organic molecules and colloids. Silicon released was dominantly monomeric silicic acid < 1 kDa. Particularly with the least podzolised soils, Al and Si concentrations < 1 kDa might have been controlled by short-range ordered aluminosilicates, while their transport in colloidal form was unlikely. Our study pointed to both quantitative and qualitative seasonality of element release during podzolisation, to decoupling of Al and Si release regarding size, and to different minerals that control element release as a function of the degree of podzolisation.
Seed dispersal by wind decreases when plants are water‐stressed, potentially counteracting species coexistence and niche evolution
(2021) Zhu, Jinlei; Lukić, Nataša; Rajtschan, Verena; Walter, Julia; Schurr, Frank M.
Hydrology is a major environmental factor determining plant fitness, and hydrological niche segregation (HNS) has been widely used to explain species coexistence. Nevertheless, the distribution of plant species along hydrological gradients does not only depend on their hydrological niches but also depend on their seed dispersal, with dispersal either weakening or reinforcing the effects of HNS on coexistence. However, it is poorly understood how seed dispersal responds to hydrological conditions. To close this gap, we conducted a common‐garden experiment exposing five wind‐dispersed plant species (Bellis perennis, Chenopodium album, Crepis sancta, Hypochaeris glabra, and Hypochaeris radicata) to different hydrological conditions. We quantified the effects of hydrological conditions on seed production and dispersal traits, and simulated seed dispersal distances with a mechanistic dispersal model. We found species‐specific responses of seed production, seed dispersal traits, and predicted dispersal distances to hydrological conditions. Despite these species‐specific responses, there was a general positive relationship between seed production and dispersal distance: Plants growing in favorable hydrological conditions not only produce more seeds but also disperse them over longer distances. This arises mostly because plants growing in favorable environments grow taller and thus disperse their seeds over longer distances. We postulate that the positive relationship between seed production and dispersal may reduce the concentration of each species to the environments favorable for it, thus counteracting species coexistence. Moreover, the resulting asymmetrical gene flow from favorable to stressful habitats may slow down the microevolution of hydrological niches, causing evolutionary niche conservatism. Accounting for context‐dependent seed dispersal should thus improve ecological and evolutionary models for the spatial dynamics of plant populations and communities.
Unveiling wheat’s future amidst climate change in the Central Ethiopia Region
(2024) Senbeta, Abate Feyissa; Worku, Walelign; Gayler, Sebastian; Naimi, Babak; Senbeta, Abate Feyissa; Biology Department, College of Natural and Computational Sciences, Hawassa University, Hawassa P.O. Box 05, Ethiopia; Worku, Walelign; School of Plant and Horticultural Sciences, College of Agriculture, Hawassa University, Hawassa P.O. Box 05, Ethiopia; Gayler, Sebastian; Institute of Soil Science and Land Evaluation, Biogeophysics, University of Hohenheim, 70593 Stuttgart, Germany; Naimi, Babak; Quantitative Biodiversity Dynamics (QBD), Department of Biology, University of Utrecht, Padualaan 8, 3584 CH Utrecht, The Netherlands; Kuhn, Arnd Jürgen; Fenu, Giuseppe
Quantifying how climatic change affects wheat production, and accurately predicting its potential distributions in the face of future climate, are highly important for ensuring food security in Ethiopia. This study leverages advanced machine learning algorithms including Random Forest, Maxent, Boosted Regression Tree, and Generalised Linear Model alongside an ensemble approach to accurately predict shifts in wheat habitat suitability in the Central Ethiopia Region over the upcoming decades. An extensive dataset consisting of 19 bioclimatic variables (Bio1–Bio19), elevation, solar radiation, and topographic positioning index was refined by excluding collinear predictors to increase model accuracy. The analysis revealed that the precipitation of the wettest month, minimum temperature of the coldest month, temperature seasonality, and precipitation of the coldest quarter are the most influential factors, which collectively account for a significant proportion of habitat suitability changes. The future projections revealed that up to 100% of the regions currently classified as moderately or highly suitable for wheat could become unsuitable by 2050, 2070, and 2090, illustrating a dramatic potential decline in wheat production. Generally, the future of wheat cultivation will depend heavily on developing varieties that can thrive under altered conditions; thus, immediate and informed action is needed to safeguard the food security of the region.

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