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While the importance of permanent grasslands (PG) for the conservation of high nature value habitats is often acknowledged, their role in most of the main sustainable food system scenarios published in the last few years is less explicit. In the best case, the place of permanent grassland in scenarios and policy agendas is their conservation; in the worst one, they are simply replaced by afforested land or cropland, considered as a better option when the focus is on GHG emissions only. In this paper, we defend the idea that several misinterpretations of the positive and negative impacts of ruminants, the 'natural' users of PG, explain why ruminants are poorly addressed by most scenarios. Based on the findings of an agroecological scenario for Europe—TYFA, standing for Ten Years For Agroecology—in which extensive permanent grassland and ruminants together play a prominent role for biodiversity conservation, nitrogen cycling and climate change mitigation and adaptation, we call for a research agenda that would better inform the specific role of PG in the provision of ecosystem services—and in particular those that depend on nitrogen management. [ABSTRACT FROM AUTHOR]

As the earth's climate changes, the ability of breeders to select for traits within forage species that impart adaptability to these changes will be critical for the maintenance of grassland agricultural systems. Temperate ‐ tropical climate transition zones (between 27 and 31° N and S latitude) have proven to be ideal zones for breeding species with variable climate adaptation. Programs located in these regions have the advantage of exposure to alternating extreme warm and cold temperatures, drought and flood conditions, and a multitude of biotic pests including fungi, viruses, insects and nematodes. In this paper we will present examples of how forage breeding programs in north‐central Florida have capitalized on these distinct advantages for selection of cultivars with resiliency to changing climate variables. Breeding programs in red clover (Trifolium pratense L.) and annual ryegrass (Lolium multiflorum Lam.) will be discussed as examples for moving cool season species into warmer climates. Species attributes that contribute to climate resiliency will be identified and described. The ability to identify small changes in genetic photoperiod responses in these regions, are illustrated as an advantage when the objective is development of earlier or later maturity. Transition zones also provide suitable environments for biotic stresses, from both tropical and temperate areas, including fungal diseases, nematodes, and insects, offering desirable field environments for screening and genetic improvement. [ABSTRACT FROM AUTHOR]

Plant dispersal and persistence strategies play an increasingly important role in the face of changing climate. Evaluating the restoration potential of soil seed banks as an important component of community resilience is crucial for developing effective grassland conservation and restoration strategies under climate change. Soil seed banks can act as a source for vegetation recovery by preserving species and supporting their establishment by assisting persistence and recolonization. In a systematic review of field and experimental seed bank studies, we evaluated the potential of seed banks in buffering climatic extremities and fluctuations. We found 42 papers testing the first‐order (temperature and precipitation changes) and second‐order effects of climate change (flooding and fire) on the seed bank in grasslands. We showed that persistent seed banks can support passive restoration especially in wetlands and habitats where unpredictable and frequent disturbance was typical in the historical timescale. We found that active restoration by seed addition will be most important in less disturbance‐adapted habitats characterized by species with transient seed banks. In such cases, the introduction of native matrix species that can tolerate the predicted climatic change should be prioritized at degraded sites. [ABSTRACT FROM AUTHOR]

Climate change is transforming precipitation regimes world-wide. Changes in precipitation regimes are known to have powerful effects on plant productivity, but the consequences of these shifts for the dynamics of ecological communities are poorly understood. This knowledge gap hinders our ability to anticipate and mitigate the impacts of climate change on biodiversity., Precipitation may affect fauna through direct effects on physiology, behaviour or demography, through plant-mediated indirect effects, or by modifying interactions among species. In this paper, we examined the response of a semi-arid ecological community to a fivefold change in precipitation over 7 years., We examined the effects of precipitation on the dynamics of a grassland ecosystem in central California from 2007 to 2013. We conducted vegetation surveys, pitfall trapping of invertebrates, visual surveys of lizards and capture-mark-recapture surveys of rodents on 30 plots each year. We used structural equation modelling to evaluate the direct, indirect and modifying effects of precipitation on plants, ants, beetles, orthopterans, kangaroo rats, ground squirrels and lizards., We found pervasive effects of precipitation on the ecological community. Although precipitation increased plant biomass, direct effects on fauna were often stronger than plant-mediated effects. In addition, precipitation altered the sign or strength of consumer-resource and facilitative interactions among the faunal community such that negative or neutral interactions became positive or vice versa with increasing precipitation., These findings indicate that precipitation influences ecological communities in multiple ways beyond its recognized effects on primary productivity. Stochastic variation in precipitation may weaken the average strength of biotic interactions over time, thereby increasing ecosystem stability and resilience to climate change. [ABSTRACT FROM AUTHOR]

Grazing can modify vegetation structure and species composition through selective consumption, modifying plant litter quality and hence decomposability. In most grasslands, moderate stocking rates maintain a mosaic of high-quality patches, preferentially used by herbivores ('grazing lawns'), and low-quality tall patches, which are avoided. In grazing lawns decomposition rates can be accelerated because of the higher litter quality of its component species and, besides, through the indirect effect of increased nutrient availability in soil. We aimed at testing this indirect effect using standard materials, comparing their decomposition in grazing lawns, open and closed tall tussock grasslands. We selected 10 patches of each type and sampled floristic composition, soil variables and cattle dung deposition. Standard materials were filter paper and Poa stuckertii litter. We prepared litterbags of 0.3 mm (thin mesh) and 1 mm mesh size (coarse mesh). Samples were incubated for 65 days in two ways: above-ground (thin and coarse mesh) and below-ground (only thin mesh), aiming at analysing the conditions for decomposition for surface litter and buried litter or dead roots, respectively. Physical and chemical soil variables did not differ among patch types, despite the differences in species composition. Closed tussock grasslands showed the lowest dung deposition, confirming the less intense use of these patches. Soil nitrogen availability (N-NO and N-NH) was not significantly different among patch types. Each standard material followed a different decomposition pattern across patch types. For above-ground incubated samples, Poa litter decomposed significantly faster in lawns, and slower in open tussock grasslands. Filter paper decomposed significantly faster in closed tussock grasslands than in the other two patch types. Decomposition of below-ground incubated samples did not significantly differ among patch types, in line with results for soil variables. Above-ground differences in decomposition may be associated with differences in microclimatic conditions resulting from differences in vegetation structure. [ABSTRACT FROM AUTHOR]

Summary1. Natural, semi-natural and artificial grasslands occur extensively around the globe, but successful management for production and biodiversity poses several dilemmas for conservationists and farmland managers. Deriving from three continents (Africa, Australia and Europe), papers in this Special Profile interface three specific issues: plant responses to grazing, plant invasions and the responses to management of valued grassland biota. 2. Although pivotal in grassland management, plant responses to grazing are sometimes difficult to predict. Two alternative approaches are presented here. The first uses natural variations in sheep grazing around a water hole to model the dynamic population response of a chenopod shrub. The second analyses a long-term grazing experiment to investigate the links between plant traits and grazing response. 3. Linked often crucially with grazing, but also driven sometimes by extrinsic factors, invasions are often cause for concern in grassland management. The invasions of grasslands by woody plants threatens grassland habitats while the invasions of pastures by alien weeds reduces pasture productivity. The papers in this section highlight how a complementary range of management activities can reduce the abundance of invaders. A final paper highlights how global environmental change is presenting new circumstances in which grassland invasion can occur. 4. The impact of grassland management on biodiversity is explored in this Special Profile with specific reference to invertebrates, increasingly recognized both for the intrinsic conservation value of many groups and for their role in ecosystem processes. The potential for manipulating flooding in wet grasslands to increase the soil invertebrate prey of wading birds is illustrated, together with the roles of management and landscape structure in enhancing insect diversity. 5. In the face of climate change and growing demands for agricultural productivity, future pressures on grassland ecosystems will intensify. In this system in which productivity and conservation are so closely bound, there is a need both to raise the profile of the issues involved, and to improve our understanding of the applied ecology required for successful management. [ABSTRACT FROM AUTHOR]

AbstractThe effect of climate change on biologically mediated soil processes is likely to be complex and difficult to predict. The direct effect of changes in soil moisture and temperature may be obscured or even reversed by changes in the return of organic substrates to the soil. This paper is the first in a series reporting the results from a medium-term investigation into the effect of simulated climate change on soil N mineralization in a seminatural calcareous grassland in southern England. Gross rates of N mineralization were determined by isotope dilution in plots subjected to winter warming (3 °C above ambient), enhanced or decreased summer rainfall and combinations of these treatments. The results from the control treatment, reported here, show a strong seasonality of gross N mineralization with rates highest in the Spring and Autumn and lowest in Summer. They indicate that water availability is the main restraint on microbial processes and plant growth and that, in the short term, enhanced summer rainfall is likely to be the main factor influencing nutrient turnover. Further papers will report the results from the imposed treatments. [ABSTRACT FROM AUTHOR]

1. Grasses using the C4 photosynthetic pathway dominate today's savanna ecosystems and account for ~20% of terrestrial carbon fixation. However, this dominant status was reached only recently, during a period of C4 grassland expansion in the Late Miocene and Early Pliocene (4–8 Myr ago). Declining atmospheric CO2 has long been considered the key driver of this event, but new geological evidence casts doubt on the idea, forcing a reconsideration of the environmental cues for C4 plant success. 2. Here, I evaluate the current hypotheses and debate in this field, beginning with a discussion of the role of CO2 in the evolutionary origins, rather than expansion, of C4 grasses. Atmospheric CO2 starvation is a plausible selection agent for the C4 pathway, but a time gap of around 10 Myr remains between major decreases in CO2 during the Oligocene, and the earliest current evidence of C4 plants. 3. An emerging ecological perspective explains the Miocene expansion of C4 grasslands via changes in climatic seasonality and the occurrence of fire. However, the climatic drivers of this event are debated and may vary among geographical regions. 4. Uncertainty in these areas could be reduced significantly by new directions in ecological research, especially the discovery that grass species richness along rainfall gradients shows contrasting patterns in different C4 clades. By re-evaluating a published data set, I show that increasing seasonality of rainfall is linked to changes in the relative abundance of the major C4 grass clades Paniceae and Andropogoneae. I propose that the explicit inclusion of these ecological patterns would significantly strengthen climate change hypotheses of Miocene C4 grassland expansion. Critically, they allow a new series of testable predictions to be made about the fossil record. 5. Synthesis. This paper offers a novel framework for integrating modern ecological patterns into theories about the geological history of C4 plants. [ABSTRACT FROM AUTHOR]

The estimation of the size and changes of soil organic carbon (SOC) stocks is of great importance for decision makers to adopt proper measures to protect soils and to develop strategies for mitigation of greenhouse gases. In this paper, soil data from the Second State Soil Survey of China (SSSSC) conducted in the early 1980s and data published in the last 5 years were used to estimate the size of SOC stocks over the whole profile and their changes in China in last 20 years. Soils were identified as paddy, upland, forest, grassland or waste-land soils and an improved soil bulk density estimation method was used to estimate missing bulk density data. In the early 1980s, total SOC stocks were estimated at 89.61 Pg (1 Pg=103 Tg=1015 g) in China's 870.94 Mha terrestrial areas covered by 2473 soil series. In the paddy, upland, forest and grassland soils the respective total SOC stocks were 2.91 Pg on 29.87 Mha, 10.07 Pg on 125.89 Mha, 34.23 Pg on 249.32 Mha and 37.71 Pg on 278.51 Mha, respectively. The SOC density of the surface layer ranged from 3.5 Mg ha−1 in Gray Desery grassland soils to 252.6 Mg ha−1 in Mountain Meadow forest soils. The average area-weighted total SOC density in paddy soils (97.6 Mg ha−1) was higher than that in upland soils (80 Mg ha−1). Soils under forest (137.3 Mg ha−1) had a similar average area-weighted total SOC density as those under grassland (135.4 Mg ha−1). The annual estimated SOC accumulation rates in farmland and forest soils in the last 20 years were 23.61 and 11.72 Tg, respectively, leading to increases of 0.472 and 0.234 Pg SOC in farmland and forest areas, respectively. In contrast, SOC under grassland declined by 3.56 Pg due to the grassland degradation over this period. The resulting estimated net SOC loss in China's soils over the last 20 years was 2.86 Pg. The documented SOC accumulation in farmland and forest soils could thus not compensate for the loss of SOC in grassland soils in the last 20 years. There were, however, large regional differences: Soils in China's South and Eastern parts acted mainly as C sinks, increasing their average topsoil SOC by 132 and 145 Tg, respectively. In contrast, in the Northwest, Northeast, Inner Mongolia and Tibet significant losses of 1.38, 0.21, 0.49 and 1.01 Pg of SOC, respectively, were estimated over the last 20 years. These results highlight the importance to take measures to protect grassland and to improve management practices to increase C sequestration in farmland and forest soils. [ABSTRACT FROM AUTHOR]

• This paper presents the results of 2 yr of CO2 flux measurements on grassland communities of varying species richness, exposed to either the current or a warmer climate. • We grew experimental plant communities containing one, three or nine grassland species in 12 sunlit, climate-controlled chambers. Half of these chambers were exposed to ambient air temperatures, while the other half were warmed by 3°C. Equal amounts of water were added to heated and unheated communities, implying drier soils if warming increased evapotranspiration. Three main CO2 fluxes (gross photosynthesis, above-ground and below-ground respiration) were measured multiple times per year and reconstructed hourly or half-hourly by relating them to their most important environmental driver. • While CO2 outputs through respiration were largely unchanged under warming, CO2 inputs through photosynthesis were lowered, especially in summer, when heat and drought stress were higher. Above-ground CO2 fluxes were significantly increased in multispecies communities, as more complementary resource use stimulated productivity. Finally, effects of warming appeared to be smallest in monocultures. • This study shows that in a future warmer climate the CO2 sink capacity of temperate grasslands could decline, and that such adverse effects are not likely to be mitigated by efforts to maintain or increase species richness. [ABSTRACT FROM AUTHOR]

The Kyoto protocol requires countries to provide national inventories for a list of greenhouse gases including N2O. A standard methodology proposed by the Intergovernmental Panel on Climate Change (IPCC) estimates direct N2O emissions from soils as a constant fraction (1.25%) of the nitrogen input. This approach is insensitive to environmental variability. A more dynamic approach is needed to establish reliable N2O emission inventories and to propose efficient mitigation strategies. The objective of this paper is to develop a model that allows the spatial and temporal variation in environmental conditions to be taken into account in national inventories of direct N2O emissions. Observed annual N2O emission rates are used to establish statistical relationships between N2O emissions, seasonal climate and nitrogen-fertilization rate. Two empirical models, MCROPS and MGRASS, were developed for croplands and grasslands. Validated with an independent data set, MCROPS shows that spring temperature and summer precipitation explain 35% of the variance in annual N2O emissions from croplands. In MGRASS, nitrogen-fertilization rate and winter temperature explain 48% of the variance in annual N2O emissions from grasslands. Using long-term climate observations (1900–2000), the sensitivity of the models with climate variability is estimated by comparing the year-to-year prediction of the model to the precision obtained during the validation process. MCROPS is able to capture interannual variability of N2O emissions from croplands. However, grassland emissions show very small interannual variations, which are too small to be detectable by MGRASS. MCROPS and MGRASS improve the statistical reliability of direct N2O emissions compared with the IPCC default methodology. Furthermore, the models can be used to estimate the effects of interannual variation in climate, climate change on direct N2O emissions from soils at the regional scale. [ABSTRACT FROM AUTHOR]