How is the invasive gorse Ulex europaeus pollinated during winter? A lesson from its native range

Many examples of plant-insect interactions have shown that selection from herbivores can act on flowering and fruiting phenology. In Ulex europaeus (Fabaceae), escaping seed predation resulted in extended, but variable flowering periods, with some plants flowering from autumn until spring and others flowering only in spring. The present study aims at understanding how gorses can have a high reproductive success during winter despite harsh climatic conditions and low number of pollinators. We measured pollen production, flower size and seed production in spring and winter, and compared the different seasons. The pollination success of flowers was high in both seasons. The flowers produced as much pollen, and were of comparable size in spring and winter, but they stayed open twice as long in winter than in spring. The high pollination rate we observed was thus due to the longer opening period of flowers and the high attractiveness of flowers during winter. However, pod abortion was higher in winter, with 43% of the flowers in winter and 75% in spring producing ripe pods. Antagonistic selective pressures exerted by biotic and abiotic interactions may, therefore, have lead to the observed flowering polymorphism, and allow U.europaeus to thrive in various climates, thus, increasing its invasiveness in different countrie

Seed predation in Ulex europaeus: a geographic and temporal mosaic of interactions

The interactions between plants and their parasites usually involve several species and present high level of variation in space and time. According to the geographic mosaic theory of coevolution, this may lead to population differentiation, large polymorphism and local maladaptation. Here we explore whether the temporal and spatial variation of the interaction between gorse (Ulex europaeus) and its seed predators can explain the polymorphism observed within and among populations of its native range. Indeed, gorse individuals present a polymorphism of flowering and fruiting phenology, and large variability for their susceptibility to seed predation. We performed a regular monitoring of five populations localised in Brittany (France) over five consecutive years. We observed the flowering and fruiting phenology of the gorses, and measured pods infestation rates by their two main seed predators, the weevil Exapion ulicis and the moth Cydia succedana. Flowering phenotypes and between year evolution of parasitism rates were conserved from year to year. Parasitism rates by weevils and moths increased over the fruiting period, and were negatively correlated one to another. Long flowering plants were more attacked by weevils, while short-flowering plants were more attacked by moths. However, the majority of the weevil larvae did not develop into adults, either because they were still at an immature stage at pod maturity, or because they were attacked by a parasitoid wasp. Year-to-year variations in the infestation rates by the two seed predators were very high, and depended on the population but not on the microclimatic conditions. These variations can thus explain the maintenance of the within populations polymorphism of gorse phenology and susceptibility to seed predation

Plant origin and ploidy influence gene expression and life cycle characteristics in an invasive weed

Background: Ecological, evolutionary and physiological studies have thus far provided an incomplete picture of why some plants become invasive; therefore we used genomic resources to complement and advance this field. In order to gain insight into the invasive mechanism of Centaurea stoebe we compared plants of three geo-cytotypes, native Eurasian diploids, native Eurasian tetraploids and introduced North American tetraploids, grown in a common greenhouse environment. We monitored plant performance characteristics and life cycle habits and characterized the expression of genes related to constitutive defense and genome stability using quantitative PCR. Results: Plant origin and ploidy were found to have a significant effect on both life cycle characteristics and gene expression, highlighting the importance of comparing appropriate taxonomic groups in studies of native and introduced plant species. We found that introduced populations of C. stoebe exhibit reduced expression of transcripts related to constitutive defense relative to their native tetraploid counterparts, as might be expected based on ideas of enemy release and rapid evolution. Measurements of several vegetative traits were similar for all geo-cytotypes; however, fecundity of tetraploids was significantly greater than diploids, due in part to their polycarpic nature. A simulation of seed production over time predicts that introduced tetraploids have the highest fecundity of the three geo-cytotypes. Conclusion: Our results suggest that characterizing gene expression in an invasive species using populations from both its native and introduced range can provide insight into the biology of plant invasion that can complement traditional measurements of plant performance. In addition, these results highlight the importance of using appropriate taxonomic units in ecological genomics investigations

How is the invasive gorse Ulex europaeus pollinated during winter? A lesson from its native range

Many examples of plant-insect interactions have shown that selection from herbivores can act on flowering and fruiting phenology. In Ulex europaeus (Fabaceae), escaping seed predation resulted in extended, but variable flowering periods, with some plants flowering from autumn until spring and others flowering only in spring. The present study aims at understanding how gorses can have a high reproductive success during winter despite harsh climatic conditions and low number of pollinators. We measured pollen production, flower size and seed production in spring and winter, and compared the different seasons. The pollination success of flowers was high in both seasons. The flowers produced as much pollen, and were of comparable size in spring and winter, but they stayed open twice as long in winter than in spring. The high pollination rate we observed was thus due to the longer opening period of flowers and the high attractiveness of flowers during winter. However, pod abortion was higher in winter, with 43% of the flowers in winter and 75% in spring producing ripe pods. Antagonistic selective pressures exerted by biotic and abiotic interactions may, therefore, have lead to the observed flowering polymorphism, and allow U. europaeus to thrive in various climates, thus, increasing its invasiveness in different countries

Material and energy flows of industrial biogas plants in Switzerland in the context of the circular economy

Today, biomass is one of many countries most important renewable energy sources. Anaerobic digestion (AD) is a promising alternative to treating organic wastes from both energy and nutrient perspectives. Here, we develop a material flow model to assess the current utilization of wet biomass in industrial AD installations from mass, energy, and nutrient perspectives in Switzerland. We then identify how the current situation fits into the circular economy concept and develop quantitative scenarios for the future of industrial AD. The nutrient transfer coefficients through AD are >74 %. In the future, this could replace up to 14,000 t/a of chemical fertilizers, saving up to 40,000 t/a of CO2-eq. Today, however, 70 t/a plastic ends up in the fields after AD, which should be improved if AD is to increase in the future. Thus, increased AD of organic wastes could reduce dependence on fossil fuels while promoting a circular economy.ISSN:2589-014

Linking Solar and Biomass Resources to Generate Renewable Energy: Can We Find Local Complementarities in the Agricultural Setting?

Today, an energy transition is underway to tackle the problems of climate change and energy sufficiency. For this transition to succeed, it is essential to use all available renewable energy resources most efficiently. However, renewable energies often bring a high level of volatility that needs to be balanced. One solution is combining the use of different renewable sources to increase the overall energy output or reduce its environmental impact. Here, we estimate the agricultural solar and biomass resources at the local level in Switzerland, considering their spatial and temporal variability using geographic information systems. We then identify the technologies that could allow for synergies or complementarities. Overall, the technical agricultural resources potential is a ~15 PJ/annum biogas yield from residual biomass and ~10 TWh/a in terms of electricity from solar photovoltaic tiles installed on roofs (the equivalent to ~36 PJ/a). Biomethane upgrading, power to X, electrolysis, cooling or photovoltaic roofing on biogas facilities are among the examples that could foster complementarity in the system if resources are pooled within the agricultural setting. Temporal complementarity at the farm scale can only lead to partial autarchy. The possible benefits of these complementarities should be further investigated, looking in particular at the economic viability of such systems

Energy generation potentials from agricultural residues: The influence of techno-spatial restrictions on biomethane, electricity, and heat production

ISSN:0306-2619ISSN:1872-911

Linking Solar and Biomass Resources to Generate Renewable Energy: Can We Find Local Complementarities in the Agricultural Setting?

Highlights: What are the main findings? Agricultural potential ~15 PJ/a biogas yield and ~10 TWh/a (36 PJ) solar electricity. Several technologies have been identified as possibilities for local complementarities. What is the implication of the main findings? Temporal complementarity at the farm scale can only lead to partial autarchy. Larger scales are more relevant for complementarities between solar and biomass resources. Today, an energy transition is underway to tackle the problems of climate change and energy sufficiency. For this transition to succeed, it is essential to use all available renewable energy resources most efficiently. However, renewable energies often bring a high level of volatility that needs to be balanced. One solution is combining the use of different renewable sources to increase the overall energy output or reduce its environmental impact. Here, we estimate the agricultural solar and biomass resources at the local level in Switzerland, considering their spatial and temporal variability using geographic information systems. We then identify the technologies that could allow for synergies or complementarities. Overall, the technical agricultural resources potential is a ~15 PJ/annum biogas yield from residual biomass and ~10 TWh/a in terms of electricity from solar photovoltaic tiles installed on roofs (the equivalent to ~36 PJ/a). Biomethane upgrading, power to X, electrolysis, cooling or photovoltaic roofing on biogas facilities are among the examples that could foster complementarity in the system if resources are pooled within the agricultural setting. Temporal complementarity at the farm scale can only lead to partial autarchy. The possible benefits of these complementarities should be further investigated, looking in particular at the economic viability of such systems.ISSN:1996-107

Long-Term Wet Bioenergy Resources in Switzerland: Drivers and Projections until 2050

In the energy sector, decisions and technology implementations often necessitate a mid- to long-term perspective. Thus, reliable assessments of future resource availability are needed to support the decision-making process. In Switzerland, similarly to other countries, only a limited part of the available wet biomass feedstock is currently used for anaerobic digestion. Understanding potential future trajectories of the available biomass amount is therefore essential to facilitate its deployment for energetic use and to establish adequate bioenergy strategies. Here, we utilized extensive government data, historical trends, and data from academic literature to identify relevant drivers and their trends. Starting with current biomass potential, the future availability and variation of resources was estimated by taking into account selected drivers and their projected future development. Our results indicated an increase of over 6% in available wet bioenergy resources by 2050 (from 43.4 petajoules (PJ) of primary energy currently to 44.3 PJ in 2035 and 45.4 PJ in 2050), where a Monte Carlo analysis showed that this projection is linked to high uncertainty. Manure remains by far the biomass with the largest additional potential. Possible consequences regarding the country’s pool of biogas facilities and their development are discussed.ISSN:1996-107

Long-Term Wet Bioenergy Resources in Switzerland: Drivers and Projections until 2050

In the energy sector, decisions and technology implementations often necessitate a mid- to long-term perspective. Thus, reliable assessments of future resource availability are needed to support the decision-making process. In Switzerland, similarly to other countries, only a limited part of the available wet biomass feedstock is currently used for anaerobic digestion. Understanding potential future trajectories of the available biomass amount is therefore essential to facilitate its deployment for energetic use and to establish adequate bioenergy strategies. Here, we utilized extensive government data, historical trends, and data from academic literature to identify relevant drivers and their trends. Starting with current biomass potential, the future availability and variation of resources was estimated by taking into account selected drivers and their projected future development. Our results indicated an increase of over 6% in available wet bioenergy resources by 2050 (from 43.4 petajoules (PJ) of primary energy currently to 44.3 PJ in 2035 and 45.4 PJ in 2050), where a Monte Carlo analysis showed that this projection is linked to high uncertainty. Manure remains by far the biomass with the largest additional potential. Possible consequences regarding the country’s pool of biogas facilities and their development are discussed