Assessment of Harvest Security of Timothy under Climate Change Condition Using a Set of Simple Criteria

According to climate change projections, the conditions for forage grass production in Northern Europe, including Norway, will change dramatically during the 21st century. The projected changes in climate in this country include increased average annual air temperature as well as increased precipitation both during the summer and winter season (Hansen-Bauer et al. 2009). In previous studies, effects of projected climate change on the above-ground biomass production, winter survival and harvest security of forage grasses have been assessed (Thorsen and Höglind 2010; Höglind et al. 2013). For example, Persson and Höglind (2013) showed a decreased dry spell period and an increased accumulated precipitation at the time of optimal harvest quality of timothy (Phleum pratense L.) at a few locations in Norway due to climate change. These results suggest increased difficulties to harvest forage grasses under future climate conditions. However, more knowledge is needed to better assess the risk of forage harvest failure due to increased rainfall and changed rainfall patterns. In this paper, we present a first attempt to quantify the risk of harvest failure of timothy grass given certain climate change scenarios, weather data downscaled from general circulation models (GCMs), and harvest management strategies

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

Effects of climate change on grassland biodiversity and productivity: the need for a diversity of models

There is increasing evidence that the impact of climate change on the productivity of grasslands will at least partly depend on their biodiversity. A high level of biodiversity may confer stability to grassland ecosystems against environmental change, but there are also direct effects of biodiversity on the quantity and quality of grassland productivity. To explain the manifold interactions, and to predict future climatic responses, models may be used. However, models designed for studying the interaction between biodiversity and productivity tend to be structurally different from models for studying the effects of climatic impacts. Here we review the literature on the impacts of climate change on biodiversity and productivity of grasslands. We first discuss the availability of data for model development. Then we analyse strengths and weaknesses of three types of model: ecological, process-based and integrated. We discuss the merits of this model diversity and the scope for merging different model types

Identifying Target Traits for Forage Grass Breeding under a Changing Climate in Norway Using the BASGRA Model

Grass-based dairy and livestock production constitutes the most important agricultural sector in Norway in economic terms, and 60% of the agricultural land in Norway is used for grass production. Climate change may have consider-able impact on the survival and productivity of grasslands, with consequences for the local supply of forage to live-stock, farmers’ income and the supply of dairy- and livestock-based food products to the global market. Farmers can adapt to climate change by choosing different grass species or cultivars or by changing management practices such as the timing and frequency of harvests. Plant breeders select new cultivars of grasses that are better suited to a specific environment and management practices by utilizing available resources in the most optimal way. A key characteristic for grass cultivars grown in Norway is their ability to survive the winter, a characteristic that will re-main important also in the future (Thorsen and Höglind 2010). Winter hardy cultivars contribute to high and stable yields, and minimize the need for costly reseeding. Other desired traits for grass cultivars in Norway are high nutritive value of the herbage, high tolerance of the plants to frequent cutting and grazing, and good suitability for conservation through ensiling. Breeding for a new grass cultivar usually takes 15-20 years. It is difficult to predict which trait combinations will be important in the future, especially under climate change conditions. However, it is important to define breeding targets and investigate the underlying genetic and physiological mechanisms of important traits. Process-based simulation models for grass can be used to evaluate the effects of altered plant traits under projected climate change conditions. Here we show an example with preliminary results from a study where the BASGRA model was used to evaluate the effect of modified plant characteristics on grass winter survival and yield under projected climate change conditions for Norway

Process-based simulation of growth and overwintering of grassland using the BASGRA model

Process-based models (PBM) for simulation of weather dependent grass growth can assist farmers and plant breeders in addressing the challenges of climate change by simulating alternative roads of adaptation. They can also provide management decision support under current conditions. A drawback of existing grass models is that they do not take into account the effect of winter stresses, limiting their use for full-year simulations in areas where winter survival is a key factor for yield security. Here, we present a novel full-year PBM for grassland named BASGRA. It was developed by combining the LINGRA grassland model (Van Oijen et al., 2005a) with models for cold hardening and soil physical winter processes. We present the model and show how it was parameterized for timothy (Phleum pratense L.), the most important forage grass in Scandinavia and parts of North America and Asia. Uniquely, BASGRA simulates the processes taking place in the sward during the transition from summer to winter, including growth cessation and gradual cold hardening, and functions for simulating plant injury due to low temperatures, snow and ice affecting regrowth in spring. For the calibration, we used detailed data from five different locations in Norway, covering a wide range of agroclimatic regions, day lengths (latitudes from 59◦ to 70◦ N) and soil conditions. The total dataset included 11 variables, notably above-ground dry matter, leaf area index, tiller density, content of C reserves, and frost tolerance. All data were used in the calibration. When BASGRA was run with the maximum a-posteriori (MAP) parameter vector from the single, Bayesian calibration, nearly all measured variables were simulated to an overall normalized root mean squared error (NRMSE) < 0.5. For many site × experiment combinations, NRMSE was <0.3. The temporal dynamics were captured well for most variables, as evaluated by comparing simulated time courses versus data for the individual sites. The results may suggest that BASGRA is a reasonably robust model, allowing for simulation of growth and several important underlying processes with acceptable accuracy for a range of agroclimatic conditions. However, the robustness of the model needs to be tested further using independent data from a wide range of growing conditions. Finally we show an example of application of the model, comparing overwintering risks in two climatically different sites, and discuss future model applications. Further development work should include improved simulation of the dynamics of C reserves, and validation of winter tiller dynamics against independent data

Performance and meat quality of suckling calves grazing cultivated pasture or free range in mountain.

The purpose of this study was to compare the effect of grazing on mountain (M) versus cultivated lowland pasture (C) on the performance and meat quality of suckling calves (Experiment 1 and 2). In addition, the effect of finishing on C after M on growth and meat quality was assessed (Experiment 2). Animals on C and M had on average similar live weight gain and carcass weight in the first experiment. However, the performance depended on year as gain and carcass weight was higher on C than on M in the first year and vice versa in the second year. In the second experiment the calves on M had lower gain and carcass weight than on C. Three week finishing on C after M compensated to some extent for the lower growth rate on M. Overall, the results indicate that mountain grazing may yield similar growth rates and slaughter weights as improved lowland pasture depending on year. There were only small effects of pasture type on carcass and meat quality traits like conformation, fatness, intramuscular fat and protein content, and fatty acid (FA) composition. The variation in FA composition could to a large extent be explained by difference in fatness with increase in monounsaturated and decrease in polyunsaturated FA with increasing intramuscular fat content, in turn varying between pasture type, experiment and year. There was a tendency that M led to higher proportion of C18:1n-9 and lower proportion of C18:1n-7 than C, which may be due to difference in milk and forage intake. Both pasture types resulted in meat with intramuscular fat with high nutritional value since the n-6/n-3 ratio was lo

Effects of integrated grassland renewal strategies on annual and perennial weeds in the sowing year and subsequent production years

Appropriate weed control measures during the renewal phase of temporary grasslands are critical to ensure high yields during the whole grassland lifecycle. The aim of this study was to determine which integrated grassland renewal strategy can most effectively control annual weeds in the sowing year and delay perennial weed re-establishment. Four split-plot trials were established at three sites dominated by Rumex spp. along a south-north gradient in Norway. The annual and perennial weed abundance was recorded during the sowing year and two or three production years. Main plots tested seven renewal strategies: 1. Spring plowing, 2. Spring plowing+companion crop (CC), 3. Summer cut+plowing, 4. Summer glyphosate+plowing, 5. Summer glyphosate+harrowing, 6. Late spring glyphosate+plowing, 7. Fall glyphosate+spring plowing+CC. Strategies 1–4 were tested in all four trials, strategy 5 in three trials, strategy 6 in two trials and strategy 7 in one trial. Plowing was performed at 20–25 cm depth, rotary harrowing at 15 cm depth, and glyphosate was applied at 2160 g a.i. ha-1. CC was spring barley (Hordeum vulgare). Subplots tested selective herbicide spraying (yes/no) in the sowing year. Results showed that effects of renewal strategies were often site-specific and differed between the sowing year and production years. Spring renewal resulted in higher perennial weed abundance than summer renewal in two out of four trials (by 3 and 12 percentage points, over all production years), and glyphosate followed by harrowing drastically increased Rumex spp. in one out of three trials (by 18 percentage points over all production years). CCs only significantly reduced perennial weed abundance in one trial (by 8 percentage points over all production years). In comparison, the selective herbicides had a strong effect on annual and perennial weeds in the sowing year in all trials. Selective herbicides reduced the weed cover from 32% to 7% cover, and averaged over the production years and sites, the perennial weed biomass fraction was 6 percentage points lower where herbicides had been applied. We conclude that while the tested renewal strategies provided variable and site-specific perennial weed control, selective herbicides were effective at controlling Rumex spp. and other perennial dicot weeds in the first two production years.publishedVersio