Biology subjects

Schob, C.

Publications and source records attributed to Schob, C..

6 recordsLinked to original sources

bioRxiv2023

Performance of a winter wheat composite cross population in two temperate agroforestry systems: a case study

In agroforestry systems (AFS), where environmental conditions are highly variable at small spatial scales, the use of uniform genetic material of a single cultivar commonly grown in monoculture cropping might not be optimal. However, the use of composite cross populations (CCPs) that contain an inherent genetic variability might be a promising approach to match the environmental variability created by trees in AFS. In this experimental trial, the performance of a CCP ( CC-2k) of winter wheat was compared to a commercial variety ( Wiwa) in a split-plot design in two AFS (Feusisberg, Wollerau) in Central Switzerland. The factor variety (p < 0.05) and the interactions of site and distance to tree (p < 0.05) and site and variety (p < 0.05) significantly affected wheat yield at the plot level. CC-2k and Wiwa yield (across all distances) amounted to 1.9 {+/-} 0.7 Mg ha-1 and 2.0 {+/-} 0.8 Mg ha-1, respectively, in Feusisberg and to 1.9 {+/-} 0.9 Mg ha-1 and 0.7 {+/-} 0.4 Mg ha-1, respectively, in Wollerau. Wiwa had a higher protein, Fe and Ca content than CC-2k. Therefore, while the CC-2k outperformed the commercial organic variety Wiwa in terms of yield in one of the two AFS, Wiwa outperformed CC-2k in terms of quality. The composite cross population might be better adapted to the heterogenous environment of agroforestry systems but fails to reach the high-quality product of modern elite cultivars. Further improvements in terms of quality might make CCPs highly interesting for diversified agricultural systems with larger environmental heterogeneity than common monoculture cropping systems.

plant biology↗

bioRxiv2023

One does not simply grow well: Performance of grassland plants in home and foreign soil and climate

O_LIPlant-soil feedbacks (PSF) play a substantial role in determining plant performance in native and foreign habitats. Yet, PSF strength may be altered by climatic parameters, creating synergies. Here, we assess performance of alpine grassland species in their native and in foreign soils in an experiment including different climates. C_LIO_LIUsing soil and seeds sampled from six alpine grassland sites spreading in a gradient from Northern Africa to Northern Europe, we compared plant performance in home soil and in five foreign soils, as well as home and foreign climates (simulated temperature and photoperiod in growth chambers). C_LIO_LIWe found that despite a high variability in plant performance between sites, plants generally performed better in their home soil and home climate, than in foreign soil or in foreign climate. However, an interaction between soil and climate effect caused this better performance in home soil to occur only when in foreign climate. Similarly, performance improved in home climate only when plants were also placed in foreign soil. C_LIO_LISynthesis: In contrast to predictions from the literature, no benefit from growing in foreign soils are indicated. At least on the short term, climate change alone is not suggested to affect native grassland plant performance. However, when introduced to a habitat with a similar climate to their native habitat, plants may perform as well as in their native range, but when introduced both to a new soil and climate, plants will do poorly. This finding sheds light on the interactive effect of climate and soil origin, as well as the possible success of plant introductions under a changing climate. C_LI

ecology↗

bioRxiv2022

Long-term spatially-replicated data show no physical cost to a benefactor species in a facilitative plant-plant interaction

Facilitation is an interaction where one species (the benefactor) positively impacts another (the beneficiary). However, the reciprocal effects of beneficiaries on their benefactors are typically only documented using short-term datasets. We use Azorella selago, a cushion plant species and benefactor, and a co-occurring grass species, Agrostis magellanica, on sub-Antarctic Marion Island, comparing cushion plants and the grasses growing on them over a 13-year period using a correlative approach. We additionally compare the feedback effect of A. magellanica on A. selago identified using our long-term dataset with data collected from a single time period. We hypothesized that A. selago size and vitality would be negatively affected by A. magellanica cover and that the effect of A. magellanica on A. selago would become more negative with increasing beneficiary cover and abiotic-severity, due to, e.g., more intense competition for resources. We additionally hypothesized that A. magellanica cover would increase more on cushion plants with greater dead stem cover, since dead stems do not inhibit grass colonization or growth. The relationship between A. magellanica cover and A. selago size and vitality was not significant in the long-term dataset, and the feedback effect of A. magellanica on A. selago did not vary significantly with altitude or aspect; however, data from a single time period did not consistently identify this same lack of correlation. Moreover, A. selago dead stem cover was not significantly related to an increase in A. magellanica cover over the long term; however, we observed contrasting results from short-term datasets. Long-term datasets may, therefore, be more robust (and practical) for assessing beneficiary feedback effects than conventional approaches, particularly when benefactors are slow-growing. For the first time using a long-term dataset, we show a lack of physical cost to a benefactor species in a facilitative interaction, in contrast to the majority of short-term studies.

ecology↗

bioRxiv2020

Using plant traits to understand the contribution of biodiversity effects to community productivity in an agricultural system

O_LIIncreasing biodiversity generally enhances productivity through selection and complementarity effects not only in natural but also in agricultural systems. However, explaining why diversity enhances productivity remains a central goal in agricultural science. C_LIO_LIIn a field experiment, we constructed monocultures, 2- and 4-species mixtures from eight crop species with and without fertilizer and both in temperate Switzerland and semi-arid Spain. We measured environmental factors and plant traits and related these in structural equation models to selection and complementarity effects to explain yield differences between monocultures and mixtures. C_LIO_LIIncreased crop diversity increased yield in Switzerland. This positive biodiversity effect was driven to almost same extents by selection and complementarity effects, which increased with plant height and C:N ratio, respectively. Also, ecological processes driving yield increases from monocultures to mixtures differed from those responsible for yield increases through the diversification of mixtures. C_LIO_LIWhile selection effects were mainly driven by one species, complementarity effects were linked to higher productivity per unit N. Yield increases due to mixture diversification were driven only by complementarity and were not mediated through the measured traits, suggesting that ecological processes beyond those measured in this study were responsible for positive diversity effects on yield beyond 2-species mixtures. C_LI

ecology↗

bioRxiv2020

Diversity increases yield but reduces reproductive effort in crop mixtures

Resource allocation to reproduction is a critical trait for plant fitness1,2. This trait, called harvest index in the agricultural context3-5, determines how plant biomass is converted to seed yield and consequently financial revenue of numerous major staple crops. While plant diversity has been demonstrated to increase plant biomass6-8, plant diversity effects on seed yield of crops are ambiguous9. This discrepancy could be explained through changes in the proportion of resources invested into reproduction in response to changes in plant diversity, namely through changes of species interactions and microenvironmental conditions10-13. Here we show that increasing crop plant diversity from monoculture over 2- to 4-species mixtures increased annual primary productivity, resulting in overall higher plant biomass and, to a lesser extent, higher seed yield in mixtures compared with monocultures. The difference between the two responses to diversity was due to a reduced reproductive effort of the eight tested crop species in mixtures, possibly because their common cultivars have been bred for maximum performance in monoculture. While crop diversification provides a sustainable measure of agricultural intensification14, the use of currently available cultivars may compromise larger gains in seed yield. We therefore advocate regional breeding programs for crop varieties to be used in mixtures that should exploit facilitative interactions15 among crop species.

ecology↗

bioRxiv2017

Positive interactions support the formation of complex spatial networks

Ecologists have recognised the effects of biotic interactions on the spatial distribution of living organisms. Yet, the spatial structure of plant interaction networks in real-world ecosystems has remained elusive so far. Using spatial pattern and network analyses, we found that alpine plant communities are organised in spatially variable and complex networks. Specifically, the cohesiveness of complex networks is promoted by short-distance positive plant interactions. At fine spatial scale, where positive mutual interactions prevailed, networks were characterised by a large connected component. With increasing scale, when negative interactions took over, network architecture became more hierarchical with many detached components that show a network collapse. This study highlights the crucial role of positive interactions for maintaining species diversity and the resistance of communities in the face of environmental perturbations.

ecology↗