Multifunctional agriculture provides noncommodity functions and services along with food, feed and bioenergy feedstocks, for example by preserving or promoting biodiversity, improving soil fertility, mitigating climate change and environmental degradation, and contributing to the socio‐economic viability of rural areas. Producing biomass for bioenergy from low‐input perennial species mixtures on marginal land has the potential to support biodiversity and soil carbon sequestration in synergy with greenhouse gas mitigation. We compared biomass production in species‐rich mixtures of perennial grasses, legumes and forbs with pure‐stand grasses and relatively species‐poor mixtures under different nitrogen fertilization regimes. Field experiments were performed on different types of marginal land, that is agricultural field margins and land with poor soil fertility, at four sites in southernmost and western Sweden. Biomass production was measured for three years in perennial grasses grown as pure stands, in legume‐grass mixtures, and legume‐grass‐forb mixtures across a species richness gradient. In unfertilized species‐rich mixtures, average biomass yields per experimental site and year were in the range from 3 to 9 metric ton DM ha⁻¹ yr⁻¹. While the most productive pure‐stand grasses fertilized with 60–120 kg N ha⁻¹ yr⁻¹ often produced higher biomass yields than unfertilized mixtures, these differences were generally smaller than the variations between years and sites. Calculations of climate impact using the harvested biomass for conversion to biogas as vehicle fuel showed that the average greenhouse gas emissions per energy unit were about 50% lower in unfertilized systems than in treatments fertilized with 100–120 kg N ha⁻¹ yr⁻¹. Our findings thereby show that unfertilized species‐rich perennial plant mixtures on marginal land provide resource‐efficient biomass production and contribute to the mitigation of climate change. Perennial species mixtures managed with low inputs thus promote synergies between productivity and biodiversity in the perspective of climate‐smart and multifunctional biomass production.

The use of the perennial grain intermediate wheatgrass (Thinopyrum intermedium (Host) Barkworth & D.R. Dewey) may have the potential to sustain soil health and fertility through the development of an extensive root system. However, references are scarce to demonstrate its potential influence in a context of a limited perennial grain growth phase, integrated into annual grain crops succession. This study aims at determining how early a perennial crop rooting system differs from that of an annual crop through root development and root traits and microbial indicators. Our results indicate that the two-year-old intermediate wheatgrass promotes a denser and deeper rooting system with proportionally more root biomass and length deeper in the soil profile. From the first growing season, the perennial grain demonstrated a suite of root traits typical of a more resource-conservative strategy, and more belowground-oriented resource allocation. Soil fungal biomass indicators were enhanced. Arbuscular mycorrhizal fungi (AMF) indicators were notably found to be improved at 1 m depth during the second growing season. This study provides evidence that grain-based agriculture can benefit from the potential of deeper and long-lived root systems of intermediate wheatgrass to manage soils. The periodic use of a short-term perennial phase in the crop rotation has the potential to improve soil functioning in the long term.

Drought is a great challenge to agricultural production, and cultivation of drought‐tolerant or water use‐efficient cultivars is important to ensure high biomass yields for bio‐refining and bioenergy. Here, we evaluated drought tolerance of four C₃ species, Dactylis glomerata cvs. Sevenop and Amba, Festuca arundinacea cvs. Jordane and Kora, Phalaris arundinacea cvs. Bamse and Chieftain and Festulolium pabulare cv. Hykor, and two C₄ species Miscanthus × giganteus and M. lutarioriparius. Control (irrigated) and drought‐treated plants were grown on coarse and loamy sand in 1 m² lysimeter plots where rain was excluded. Drought periods started after harvest and lasted until 80% of available soil water had been used. Drought caused a decrease in dry matter yield (DM; P < 0.001) for all species and cultivars during the drought period. Cultivars Sevenop, Kora and Jordane produced DM at equal levels and higher than the other C₃ cultivars in control and drought‐treated plots both during and after the drought period. Negative correlations were observed between stomatal conductance (g_s) and leaf water potential (P < 0.01) and positive correlations between g_s and DM (P < 0.05) indicating that g_s might be suitable for assessment of drought stress. There were indications of positive associations between plants carbon isotope composition and water use efficiency (WUE) as well as DM under well‐watered conditions. Compared to control, drought‐treated plots showed increased growth in the period after drought stress. Thus, the drought events did not affect total biomass production (DM_total) of the whole growing season. During drought stress and the whole growing season, WUE was higher in drought‐treated compared to control plots, so it seems possible to save water without loss of biomass. Across soil types, M. lutarioriparius had the highest DM_total (15.0 t ha⁻¹), WUE_total (3.6 g L⁻¹) and radiation use efficiency (2.3 g MJ⁻¹) of the evaluated grasses.

The concept of green façades is not new (Koehler, 2008), but their reintroduction may offer benefits in the current urban design, which is increasingly focused on urban densification. The benefits of vertical greening include noise abatement (Van Renterghem et al., 2013), filtering of airborne dust and pollutants (Ottele et al., 2010 and Sternberg et al., 2010), and reduction of temperature close to the area of vertical greening (Onishi et al., 2010, Wong et al., 2010 and Perini et al., 2011a). The thermal aspects of vertical greening are, however, still under debate (Hunter et al., 2014). One particular type of green façade is living wall systems, which are vertical greening systems where plants are grown without the need for contact with the ground (Koehler, 2008, Francis and Lorimer, 2011 and Perini et al., 2011b). Living wall systems can be seen as an alternative way of introducing urban greening in dense urban areas in the same way as e.g. green roofs, which have shown to support a high arthropod diversity (Rumble and Gange, 2013 and Madre et al., 2013). Like plants on green roofs (Emilsson and Rolf, 2005 and Emilsson, 2008), plants in living wall systems must be able to cope with extreme conditions, such as high irradiation, considerable differences in temperature and possible water shortage. The main aim of this study was to determine whether it is possible to grow perennial plants in living wall systems in the Scandinavian climate and we hypothesized that perennial plants could survive in, and would be a viable option for, living wall systems in the Scandinavian climate