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Implementing a fodder tree hedgerow system in permanent grasslands as supplementary forage resources 

AgroForageTree, 2024-2028, SNSF project n°215044 (PhD Julie Botzas-Coluni)

Agroforestry for forage production could be a promising solution to provide additional tree-based forage, especially during summer, when risks of drought-induced decrease in forage production are the highest. Leaves of specific fodder tree species, such as Fraxinus spp., Morus spp. and Salix spp. can have excellent digestibility and nutritional value for livestock. Moreover, many fodder tree species achieve their maximum leaf production over summer and they can maintain high leaf forage quality until late summer/early autumn, i.e. when forage yield, quality and digestibility of herbaceous species generally decrease, above all during drought periods. The AgroForageTree project aims at evaluating the potential of fodder tree hedgerows to provide supplementary tree-based forage (in addition to grass-based forage) in late summer-beginning of autumn and is organized following four main objectives, i) monitoring the survival, annual growth and photosynthetic activity of five selected fodder tree species in different permanent grassland sites across an altitudinal and climatic gradient, ii) determining leaf production and leaf chemistry and digestibility of the five fodder tree species and their variation along the vegetation season, iii) investigating the impacts of fodder tree hedgerows on ecosystem biodiversity and services after the establishment of the agroforestry system, and iv) assessing the palatability and selection for the five fodder tree species by different livestock categories, as well as methane emissions, nutrient absorption and digestibility resulting from the tree-grass diet.


Determining drought-resistant mixtures for temporary mountain grasslands 

DryMount, 2023-2027, Funding from Agroscope and Swiss Cantons (PhD Emilie Roinel)

Permanent grasslands play a pivotal role in Switzerland because of the forage yield and quality they produce, mainly resulting from the productivity of a few dominant species with functional traits associated with acquisitive resource strategy. By contrast, numerous low abundant species, which have traits associated with conservative resource strategy, tend to grow slower and produce less biomass than these dominant species. However, they may be more resistant to drought and compensate for the decline of more competitive dominant species during drought events. This four-year project aims to assess the resistance of different permanent mountain grassland mixtures to summer drought events, simulating future climate change scenarios on Swiss mountain areas. Nine new mixtures were created to evaluate the best compromise between productivity and drought resistance. The mixtures are based on the dominance of the main, more productive species and the proportion of species considered drought-resistant. They are dominated either by cocksfoot or meadow foxtail, or by these two species together, supplemented by other species common to standard mixtures. Drought-resistant species (red fescue, ribwort plantain, common bent and birdsfoot trefoil) are added to this basic mix. Two mixtures commonly sown in mountain areas serve as controls. A total of 11 mixtures are sown on the 5 sites of the project in May-June 2023, along a rainfall gradient (850 to 1600 mm). Drought events will be tested by means of rainout shelters compared to ambient conditions at one site. The results of this study will guide the choice of drought-tolerant mixtures for sustainable delivery of mountain grassland services and increase general understanding of the response of temporary grassland communities to future drought.

Disturbance and resources across global grasslands 

DRAGNet2020-2025, Agroscope site - Changins

DRAGNet will quantify community assembly dynamics and trajectories of herbaceous plant community and ecosystem recovery under a wide range of biotic and abiotic conditions, and test whether assembly, recovery rate, or trajectory in herbaceous-dominated plant communities interacts with environmental nutrient enrichment. This experiment is timely and widely relevant because physical disturbances are among the most pervasive impacts of humans on Earth. Although disturbances are an important driver of community dynamics and assembly, they now occur concurrent with other human impacts including climate change and nutrient deposition. The four primary goals of DRAGNet are to (i) quantify community assembly, vegetation recovery rates, and trajectories of change after disturbance across a wide variety of herbaceous-dominated sites under ambient and elevated nutrient supply, (ii) determine the relative importance of local and regional processes for community assembly by pairing theoretical models with core and additional “add-on” seed bank/seed rain data, (iii) quantify community resistance to, and resilience after, short-term nutrient addition, and (iv) gain insights into the reproducibility of ecological experiments by leveraging plot-level data from sites already participating in NutNet and replicating the same treatments (control and nutrients) in different starting years. 

Sustainable agricultural production systems

SPAD, 2020-2023, Interreg France-Switzerland project n°6125

Grasslands are the core of forage production worldwide and are severely threatened by climate changes, which can strongly reduce grassland productivity. Climate change is happening at a worldwide scale but not all parts of the world are affected similarly. Thus, understanding local and regional effects of climate change on grassland ecosystems is crucial to adapt management practices accordingly and ensure sufficient forage production. The goal of the SPAD project is to increase sustainability and adapt food production systems to climate change in the French departments of Doubs, Territoire de Belfort, Haute-Saône and Jura, as well as in the Swiss cantons of Jura and Jura Bernois. The novelty of the project consists in including quantitative criteria of sustainability based on local farming conditions (grassland type, common management practices, production system). Based on local climatic scenarios, future sustainability and environmental impacts of farms will be determined and adapted management practices will be developed to mitigate such impacts and increase the sustainability of grassland systems at the regional scale.


Targeted grazing of robust livestock for the restoration of green alder-encroached pastures

ROBUSTALPS, 2019-2023, SNSF project n°184925 (PhD Mia Svensk)

Throughout the last decades, the reduction of agro-pastoral activities in Swiss mountain areas has determined profound landscape modifications, with extensive reforestation processes over former pastures, particularly by green alder (Alnus viridis), which is the most expanding shrub species across all Central Europe. The project aims to investigate specific ecological dynamics, such as botanical composition evolution and N translocation fluxes, in A. viridis-encroached pastures under the challenge of targeted grazing. We propose to strategically place attractive points (AP), i.e. molasses-based salt blocks, within encroached areas to increase their exploitation by robust livestock species (here Highland cattle). With AP placement, we expect to increase the time spent by livestock herds within A. viridis-encroached areas, their consumption of green alder foliage, N content in their excreta, and consequently N translocation towards livestock resting areas. Moreover, thanks to the actions exerted by animals around AP locations, such as increased A. viridis defoliation, mechanical damages to green alder branches by trampling, as well as seed transportation, significant variations in vegetation communities are also expected, with beneficial effects on the restoration of typical pasture botanical composition. Therefore, this research could help filling knowledge gaps on the (i) forage potential of A. viridis foliage for robust animals, (ii) short-term vegetation dynamics after intense livestock pressure in green alder-dominated areas, (iii) and N redistribution fluxes within encroached pastures. As a consequence, it could provide useful insights to design innovative and sustainable grazing management systems for the restoration of A. viridis-encroached pastures.

Integrated tools for optimised grassland and forage utilisation 

INTOGRASS, 2018-2021, Agroscope project

Swiss grasslands supply multiple benefits and services as a function of their management, the plant species of which they are composed, and pedo-climatic conditions. Thanks to the development of cross-disciplinary decision-support tools, the farmer or any other decision-maker should be able to grasp these services in their multiplicity and optimise them for contrasting conditions and production systems. Managing grasslands also means managing species communities. To make the best use of these communities, we must also know about grass growth and quality, and master grassland conservation. The ‘IntoGrass’ project aims to develop tools to facilitate grassland management, grass utilization and grass quality assessment, focusing particular attention on the effect of pedo-climatic factors. Launched in 2017, this transdisciplinary project involves four Agroscope teams, and is based on a network of 32 grasslands distributed across Switzerland, which will help us better understand the impact of climatic conditions (temperature, precipitation) on grass growth and quality.


Interactive effects of altitude and management on resistance and resilience of permanent grasslands to drought: combining agronomic, functional and ecophysiological approaches 

GRASSALT, 2016-2019, SNSF project n°156282 (PhD Amarante Vitra)

Grasslands are at the core of Swiss agriculture and justify financial support of the government, whose agricultural policy supports forage autonomy of herbivore herds. Identifying potential interactive effects of different factors, such as altitude and management, with different climate change scenarios is therefore a major challenge to anticipate the performance of grasslands and the reliability of production in the future. The project focused on the response of grasslands to simulated early and late-season droughts along an altitudinal gradient and according to two management schemes. The objective of the project were twofold: i) provide agronomical references and management clues for forage production under altered precipitation regimes, ii) identify ecological mechanisms that drive grassland response to drought events. To achieve both goals, agronomical monitoring were combined with ecological approaches. A plant functional approach was implemented to address changes in community functional traits in response to altered environmental conditions. Moreover, relevant and innovative ecophysiological measurements were developed to assess drought resistance mechanisms at the plant species level. The project significantly added in our understanding of the response of grassland communities to future climate variability, and contributed to ecological theories. Further, the project included an effective integration of fundamental ecological principles into an agronomic issue, and led to the development of references directly relevant to agriculture.

Climate change impacts on soil N:P stoichiometry and consequent feedback on plant-microbe interactions in Australian grasslands 

Advanced postdoctoral fellowship, 2014-2016, SNSF project n°144648

In South-Australia, a trend of prolonged periods without rain, alternated with increasing rainfall intensity, has already emerged during the last 50 years and is likely to continue during this century. Drought impact on the relative supply of nitrogen (N) and phosphorus (P) to plants and microbes but because plants and microbes have limited flexibility to take up N and P under conditions of unbalanced supply, drought affecting N:P stoichiometry can have large impacts on primary productivity and carbon sequestration. By using field and glasshouse experiments, this project aimed at assessing limitation of soil N and P for plant growth and microbes under climate change (drought) in Australian grasslands. Isotopes tracers (15N, 32P) were used to determine N and P uptake by plants and microbes under drought. Moreover, several ecosystem functions were measured in order to related changes in soil N:P stoichiometry, plant and microbes uptakes and grassland functioning and sustainability. This project identified important drought resistance mechanisms and provided tools to improve predictions about drought impacts on productivity and nutrient availability, that have important implications for grassland management.

Exploring threshold dynamics in noxious plant invasion of Californian rangelands 

Early postdoctoral fellowship, 2013-2014, SNSF project n°146538)

Alternative states represent major shifts in ecosystem function due to changes in abundance and composition of dominant species, and associated biological and physical processes. The objectives of this project were to determine how feedbacks between plants and soil and threshold dynamics influence the establishment of noxious weed invasion. In this project, we used the noxious weed Medusahead (Elymus caput-medusae) that is target for management intervention in Californian rangelands. Indeed, weed infestations by Medusahead on annual rangeland can reduce forage production by 75-80%. In this study, we used seed addition experiments, in the Sierra Foothills Research Extension Center, to establish populations of different densities. Then, we followed population dynamics and changes in soil properties and soil microbial communities. We also studied the role of litter accumulation on the growth of the invasive and introduced species. Overall, we tested the generalities and predictability of patch formation and spatial contagion, widely thought to be critical components of abrupt and sudden threshold effects, in weed invasion. 

Effects of subordinate plant species on plant and soil community structure and ecosystem functioning

SUBFUNC, PhD thesis, 2008-2012, SNSF project n°114139

Despite their low relative abundance, subordinate plant species may have larger impacts on ecosystem functioning than expected, but their role in plant communities remained poorly understood. While dominant species are supposed to be the most important species-group in plant communities, I demonstrated, during my PhD research, that subordinate species may also play a role in ecosystem functioning. Using removal experiments in two field sites of semi-natural mountain grasslands (Swiss Jura), I demonstrated that the loss of subordinate species can have significant consequences for soil microbial communities (especially fungi) and ecosystem functions (biomass production, soil respiration, litter decomposition), suggesting that subordinate species are important drivers of ecosystem properties. 

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