Mixed Grazing Increases Abundance of Arbuscular Mycorrhizal Fungi in Upland Welsh Grasslands

Grasslands play a crucial role in exchanges between global ecosystems and the atmosphere and form an integral part of the agricultural industry. Arbuscular mycorrhizal fungi (AMF) are mutualistic symbionts of most grassland plant species and thereby influence the functional capacity of grassland systems. Agricultural grasslands are primarily used for livestock farming and are subjected to various management practices designed to increase production, but which also alter both plant and soil communities in the process. This research investigated the effects of a selection of management practices and environmental factors on the presence and abundance of AMF in upland Welsh grasslands. The aim was to identify how these management practices affected the abundance of AMF, assessed through microscopic observations of four AMF structures: spores, hyphae, vesicles and arbuscules. The results suggest grazing sheep and cattle together had the highest overall influence on AMF abundance compared to grazing sheep or cattle separately. High plant diversity correlated with high arbuscule and vesicle abundance, but conversely, the application of lime reduced vesicle abundance. These findings offer new insights into the effects of management practices on AMF. Mixing livestock, increasing plant diversity and reducing lime applications are shown here to improve the abundance of AMF and could, therefore, help to inform sustainable farm management decisions in the future

Direct and indirect health impacts of climate change on the vulnerable elderly population in East China

The latest scientific advances on the impacts of climate change on the health of the elderly in East China were reviewed consulting peer-reviewed publications from 2000-2017. The direct impacts of climate change result from rising temperatures, heatwaves, and increases in the frequency of complex extreme weather events such as windstorms, floods, and droughts. The health and social consequences of these events are far-reaching, ranging from reduced labour productivity and heat-related deaths, through to direct physical injury during extreme weather events, the spread of infectious diseases, and mental health effects following widespread flooding or prolonged drought. Research has indicated that climate change will have the greatest impact on vulnerable groups of people, including the elderly population. However, there is a dearth of empirical evidence, a lack of focus on vulnerable segments of the population (especially elderly), limited understanding of how health status will change in the future, and lack of acknowledgement of how different regions in China vary in terms of the consequences of climate change. The main risk in East China that climate change may exacerbate is flooding (sea level rise, coastal and riverine, flood risk). However in some regions of East China such as in the provinces of Anhui, Jiangsu, Hebei and Shandong the biggest climate change risk is considered to be drought. Main health risks linked to climate change are evident as cardiovascular and respiratory diseases (heat stroke, exhaustion, and asthma), often caused by interactions between heatwave episodes and concurrent poor air quality

Mycorrhizal fungal abundance is affected by long-term climatic manipulations in the field

Climate change treatments - winter warming, summer drought and increased summer precipitation - have been imposed on an upland grassland continuously for 7 years. The vegetation was surveyed yearly. In the seventh year, soil samples were collected on four occasions through the growing season in order to assess mycorrhizal fungal abundance. Mycorrhizal fungal colonisation of roots and extraradical mycorrhizal hyphal (EMH) density in the soil were both affected by the climatic manipulations, especially by summer drought. Both winter warming and summer drought increased the proportion of root length colonised (RLC) and decreased the density of external mycorrhizal hyphal. Much of the response of mycorrhizal fungi to climate change could be attributed to climate-induced changes in the vegetation, especially plant species relative abundance. However, it is possible that some of the mycorrhizal response to the climatic manipulations was direct - for example, the response of the EMH density to the drought treatment. Future work should address the likely change in mycorrhizal functioning under warmer and drier conditions

Re-evaluating the sensitivity of habitats to climate change

This report presents the results of an expert led assessment that refines our understanding of the sensitivity of habitats to climate change. Using the Delphi technique and a panel of academic and practitioner experts, an externally validated 5-point scale of sensitivity was developed for habitats in good and degraded condition. The assessment will guide the prioritisation of interventions to those habitats most sensitive to climate change and thus support efforts to reduce climate risk and support nature recovery

Functional sustainability of nutrient accumulation by periphytic biofilm under temperature fluctuations

Temperature can fluctuate widely between different seasons, and this may greatly impact many biological processes. However, little is known about its influence on the functioning of benthic microbial communities. Here we investigated the nutrient accumulation capability of periphytic biofilm under temperature fluctuations (17–35°C). Periphytic biofilm maintained the same nutrient accumulation capacity after experiencing the ‘warming-hot-cooling’ temperature fluctuation under both lab and outdoor conditions as those without temperature disturbance. In response to temperature increase, both community composition and species richness changed greatly and the increase in biodiversity was identified as being the underlying mechanism boosting the sustainable function in nutrient accumulation, indicating zero net effects of community changes. These findings provide insights into the underlying mechanisms of how benthic microbial communities adapt to temperature fluctuations to maintain nutrient accumulation capacity and elucidate that periphytic biofilm plays important roles in influencing nutrient cycling in aquatic ecosystems under temperature changes such as seasonal fluctuations

Seasonal variation in the response of arbuscular mycorrhizal fungi to grazing intensity

Despite existing evidence of pronounced seasonality in arbuscular mycorrhizal (AM) fungal communities, little is known about the ecology of AM fungi in response to grazing intensity in different seasons. Here, we assessed AM fungal abundance, represented by soil hyphal length density (HLD), mycorrhizal root colonization intensity (MI), and arbuscule intensity (AI) throughout three seasons (spring, summer, autumn) in a farm-scale field experiment in typical, grazed steppe vegetation in northern China. Seven levels of field-manipulated, grazing intensities had been maintained for over 13 years within two topographies, flat and slope. We also measured soil nutrients and carbon content throughout the growing season to investigate whether seasonal variation in AM fungal abundance was related to seasonal shifts in soil resource availability along the grazing gradient. We further examined the association between AM fungal metrics in the different grazing treatments through the growing season. Our results showed a pronounced seasonal shift in HLD but there was no clear seasonality in MI and AI. HLD was significantly negatively related to grazing intensity over the course of the growing season from spring to autumn. However, MI and AI were related negatively to grazing intensity only in spring. In addition, differential responses of AM fungal abundance to grazing intensity at the two topographical sites were detected. No strong evidence was found for associations between AM fungal abundance and soil resource availability. Moreover, AM fungal internal and external abundance were correlated positively under the different grazing intensities throughout the growing season. Overall, our study suggests that external AM fungal structures in soil were more responsive to seasonal variation and grazing than internal structures in roots. The findings also suggest that early grazing may be detrimental to AM fungal root colonization of newly emerged plants

Long-Term Grazing Intensity Impacts Belowground Carbon Allocation and Mycorrhizas Revealed by 13CO2 Pulse Labeling

Despite the importance of grasslands for carbon storage and climate regulation, there is uncertainty about the effect of livestock grazing intensity on aboveground carbon assimilation and belowground carbon partitioning. Furthermore, the relationship between belowground carbon allocation and arbuscular mycorrhizal fungi, which serve as a conduit for carbon movement through the plant and soil, is unclear. To investigate this, we used an in situ 13C stable isotope pulse-chase labeling approach in plots under seven rates of sheep grazing intensity in a steppe grassland in northern China. We quantified the allocation of carbon to plants, soil, and soil-respired CO2 along with measurements of mycorrhizal hyphal density in the soil. With increasing grazing intensity, carbon assimilation per unit shoot biomass increased significantly, whereas carbon allocation to roots marginally decreased. Soil-respired CO2 appeared to be independent of grazing intensity. Mycorrhizal hyphal density decreased with increasing grazing intensity and was correlated significantly with new carbon input to roots 2 d after labeling and marginally related to that of soil 1 d after the 13C-CO2 pulse. Our study suggests that grazing intensity alters the distribution of carbon among different carbon pools within the plant-soil system. The results also underscored the key role of mycorrhizas as a fast route for carbon transfer from plant to soil

The response of grassland mycorrhizal fungal abundance to a range of long-term grazing intensities

Keystone root symbiotic arbuscular mycorrhizal fungi play a major role in maintaining plant biodiversity, increasing plant productivity and enhancing storage of carbon in soil. AM fungi are ubiquitous and found in most ecosystems including grasslands currently experiencing increasing pressures form human activity. Grazing is known to impact AM fungi but very little is known about how AM fungi are affected by different levels of grazing intensity. Here we report on results from a long-term experimental site in a typical steppe in the north of China, containing seven levels of field-manipulated grazing intensities maintained for over 13 years. We assessed arbuscular mycorrhizal fungal abundance, represented by soil hyphal length density and mycorrhizal root colonization (mycorrhizal root frequency, intensity and arbuscule intensity) within the farm-scale field experiment. We also measured environmental variables to explain the responses of mycorrhizal fungi to grazing intensity. Our results showed that with an increase in grazing intensity, soil hyphal length density linearly decreased. There was, however, no significant trend for mycorrhizal root colonization variables in relation to grazing intensity. Mycorrhizal root frequency was negatively correlated with topographic-induced changes in soil nitrogen and phosphorus, while arbuscule intensity was marginally negatively correlated with soil available phosphorus. Further, we found a possible hump-shaped relationship between the ratio of external to internal AM fungal structures and grazing intensity. Our finding showed that external AM fungal structure was clearly impacted by grazing intensity but that this was not the case for internal mycorrhizal structures. This indicated that mycorrhizal functioning was impacted by the intensity of grazing as the mycorrhizal structures responded differently. Indeed the ratio of the foraging extra-radical mycorrhizal hyphae to intra-radical mycorrhizal structures was highest at moderate grazing intensity but strongly decreased by high grazing intensity. Our study suggests that the impacts of grazing intensity on the plant-AMF association could lead to further knock-on effects on the plant-soil system via the feedbacks that exist between plant and AMF communities

Project Report No. PR640-02: Optimal grazing management to enhance soil biodiversity and soil carbon in upland grassland

Here we report on a project instigated by and co-designed with a group of livestock farmers in Wales who wanted to know more about the health and sustainability of their grassland soils. The core aim of the project was to enhance the sustainability and resilience of livestock production relying on grassland whilst maintaining ecosystem services such as carbon sequestration and biodiversity provision. Soil carbon and nitrogen content and soil biodiversity measurements were obtained to determine whether these were being impacted by grazing management. The farmers were interviewed to determine the role of soil health in decision making as well as how best to communicate complex science evidence

Qualitative Impact Assessment of Land Management Interventions on Ecosystem Services (“QEIA”). Report-1: Executive Summary: QEIA Evidence Review & Integrated Assessment

The focus of this project was to provide an expert-led, rapid qualitative assessment of land management interventions on Ecosystem Services (ES) proposed for inclusion in Environmental Land Management (ELM) schemes. This involved a review of the current evidence base for 741 land management actions on 33 Ecosystem Services and 53 Ecosystem Service indicators by ten teams involving 45 experts drawn from the independent research community in a consistent series of Evidence Reviews covering the broad topics of: • Air quality • Greenhouse gas emissions • Soils • Water management • Biodiversity: croplands • Biodiversity: improved grassland • Biodiversity: semi-natural habitats • Biodiversity: integrated systems-based actions • Carbon sequestration • Cultural services (including recreation, geodiversity and regulatory services). It should be noted that this piece of work is just one element of the wider underpinning work Defra has commissioned to support the development of the ELM schemes