Frost Tolerance, Deacclimation and Reacclimation Traits in Perennial Ryegrass

The ability of perennial grasses to harden and maintain frost tolerance throughout the winter is crucial for winter survival. This includes the ability to resist deacclimation during transient mild spells in winter, and the ability to reacclimate when cold temperatures return. The latter traits are especially critical in regions with cycles of freezing and thawing, and lack of a stable, insulating snowcover that can protect the plants from extreme air temperatures. Such conditions are typical for many coastal areas in Northern Eurasia and America, such as the southwestern coast of Norway. The climate is changing and one of the consequences for Norway will be milder winter temperatures. This might open up for increased use of perennial ryegrass (Lolium perenne L.) in Scandinavian forage grass production systems at the expense of timothy (Phleum pratense L.), the most commonly used forage grass today. However, there are still important questions about the winter survival of perennial ryegrass under future climate conditions that needs to be addressed before a wider use of this grass species can be recommended. One is related to the risk of frost injury connected with more fluctuating temperatures at plant level in winter and spring. Thus, simulation studies using a grassland model parameterized for current winter-hardy cultivars of perennial ryegrass indicated an increased risk of frost injury in winter and spring in many areas of North Europe including Norway (Höglind et al., 2013). The increased risk was associated with a reduced snow cover, and earlier onset of spring growth followed by frosts. The simulation results indicate that cultivars that can resist deacclimation and/or that can reacclimate to a substantial degree will be needed for successful grass production under the projected future climate conditions. However, more information is needed about the genetic variation with respect to deacclimation resistance and reacclimation capacity. The aim of the present work was to compare three cultivars of perennial ryegrass with respect to their resistance to dehardening and ability to reharden under fluctuating winter temperatures. The plants differed widely with respect geo-climatic origin. Plants were first hardened under controlled conditions, and then subjected to a period of mild temperatures followed by decrease to pre-dehardening temperatures. Frost tolerance was estimated by freezing tests after completed hardening, twice during the mild episode and twice after the return to pre-hardening conditions. Our hypothesis was that the deacclimation and reacclimation characteristics would differ largely between the cultivars given their contrasting geo-climatic origin

Sedum root foraging in layered green roof substrates

Background and aims Layered profiles of designed soils may provide long-term benefits for green roofs, provided the vegetation can exploit resources in the different layers. We aimed to quantify Sedum root foraging for water and nutrients in designed soils of different texture and layering. Methods In a controlled pot experiment we quantified the root foraging ability of the species Sedum album (L.) and S. rupestre (L.) in response to substrate structure (fine, coarse, layered or mixed), vertical fertiliser placement (top or bottom half of pot) and watering (5, 10 or 20 mm week−1 ). Results Water availability was the main driver of plant growth, followed by substrate structure, while fertiliser placement only had marginal effects on plant growth. Root foraging ability was low to moderate, as also reflected in the low proportion of biomass allocated to roots (5–13%). Increased watering reduced the proportion of root length and root biomass in deeper layers. Conclusions Both S. album and S. rupestre had a low ability to exploit water and nutrients by precise root foraging in substrates of different texture and layering. Allocation of biomass to roots was low and showed limited flexibility even under water-deficient conditions.Sedum root foraging in layered green roof substratesacceptedVersio

The multifunctionality concept in urban green infrastructure planning: A systematic literature review

Urban green infrastructure is critical for providing a wide range of ecosystem goods and services that benefit the urban population. Past studies have suggested that multifunctionality concerning urban infrastructure services and functions is a prerequisite for targeting effective and impactful urban green infrastructure. Moreover, urban green infrastructure with multiple functions can offer socio-economic and environmental benefits. However, there has been a knowledge gap in the planning literature to elaborate multiple ecosystem functions in urban green infrastructure. In particular, existing methods and approaches are lacking for quantifying and monitoring such ecological services and biodiversity in urban green infrastructures at different spatial scales. Therefore, this research aims to review studies focusing on the multifunctionality concept in urban green infrastructure planning. The study highlights the current status and knowledge gaps through a systematic review. Our analysis revealed that current studies on green infrastructure multifunctionality have focused on five main themes: 1) planning methods for urban green infrastructure, 2) assessment approaches of urban green infrastructure, 3) ecosystem services and their benefits, 4) sustainability and climate adaptation, and 5) urban agriculture. The study found that the five themes are somewhat connected to each other. The study has revealed a knowledge gap regarding incorporating multifunctional green infrastructure in the planning principle. The results suggest at least five critical elements to ensure multiple functions in urban infrastructure. The elements are spatial distribution, optimal distance, integrated network, accessibility, and public participation and engagement. The study further recommends research directions for future analysis on green infrastructure multifunctionality that are critical for urban planning.publishedVersio

Impacts of organic soil amendments on forage grass production under different soil conditions

Organic amendments can improve grassland productivity. Timothy and tall fescue were sown on a sandy loam and a coarse sand at Særheim, Norway, in September 2016 and on a loamy sand at Skierniewice, Poland, in April 2017, and cut and fertilised according to normal practices for the two regions from 2017 to 2019. At both sites, 0.75 kg DM m-2 of either digested or undigested manure (the latter with or without 2.9 kg biochar m-2) were incorporated prior to sowing. On the coarse sand at Særheim, total seasonal tall fescue yield in 2018 was 46–60% higher in the organic amendment treatments, and total seasonal timothy yield in the digestate treatment was 97% higher, than in the control treatment for the same species with only mineral fertiliser. On the sandy loam at Særheim and the loamy sand at Skierniewice, none of the amendments resulted in significant yield increments. These results indicate a clear effect on soil type on grassland biomass response to organic amendments

N fertilization strategies for the use of P-rich organic amendments in the restoration of soil productivity—short-term responses in two soils

To facilitate nutrient management and the use of manure as a feedstock for biogas production, manure is often separated into a solid and a liquid fraction. The former fraction is usually high in P and low in N, so when incorporated in the soil as fertilizer, it needs to be supplemented by N from, e.g., mineral fertilizers or nitrogen-fixing species. To explore strategies to manage N with solid-separated manure, we examined how the amount of digestate and the N:P ratio of pig digestate, i.e., manure that had partially undergone anaerobic digestion, affected the productivity of Westerwolds ryegrass and red clover in a pot experiment with one soil which was rich and another which was poor in plant nutrients. The soil and plant species treatments were combined with four doses of digestate, which gave plant available phosphorus (P) concentrations of 2, 4, 8, or 16 mg P100 g−1 soil. Ammonium nitrate was dosed to obtain factorial combinations of digestate amount and N:P ratios of 1.8, 4, 8, and 16. Clover was harvested once at the beginning of flowering (15 weeks after seeding), while Westerwolds ryegrass was allowed to regrow three times after being cut at the shooting stage (in total, 4 cuts, 6, 9, 12, and 15 weeks after seeding). Ryegrass yield increased by up to 2.9 times with digestate dosage. Interactions with the N:P ratio and soil type were weak. Hence, the effect of increasing the N:P ratio was additive across digestate dosages. Red clover biomass also increased by up to 39% with digestate dosage. Residual nutrients in the soil after red clover cultivation were affected by the initial differences in soil characteristics but not by digestate treatment or biomass of harvested red clover. A targeted N management is required to benefit from the P-rich digestate in grass cultivation, while the long-term effects of red clover culture on N input need further investigation