Late Holocene regime shifts in moorland ecosystems : high-resolution data from the Pennines, UK

This research was funded by the Economic and Social Research Council through the Rural Economy and Land-Use Programme (RES-229-27-0003).Identifying critical shifts in ecosystems caused by human impacts has become a priority for understanding resilience to change and setting realistic management goals. Previous work suggests that many British blanket peats have suffered a loss of functional integrity over recent centuries, but it is unclear whether all moorland habitats are equally vulnerable. This study examines the relative sensitivity of four contrasting moorland communities to historic land-use changes and assesses whether these management pressures are pushing some moorlands beyond their Holocene range of variability. Late Holocene dynamics in the Peak District, northern England, were investigated using high-resolution pollen, fungal spore and charcoal data, and multivariate analyses. All sites show high Calluna values during the nineteenth century and converge on local Poaceae-dominance during the twentieth century. This involved a shift from gradual or cyclical variability and moderate changes in pollen abundance during preceding centuries, to rapid transitions between mono-dominant pollen assemblages and a functional shift to taxa with competitive traits; these are interpreted as a regime shift. Evidence for the recent recovery of dwarf-shrubs and Sphagnum is strong at one site, with slight evidence from two others, but disturbance could push the system back to grass-dominance. The deep blanket peat site may have crossed a threshold, leading to a persistent grass-dominated state. Studying regime shifts on decadal to centennial scales can help bridge the gap between ecology and palaeoecology by providing a robust basis for assessing vulnerability, setting restoration priorities and managing novel peatland states.PostprintPeer reviewe

High spatial resolution Holocene vegetation and land-use history in West Glen Affric and Kintail, Northern Scotland

Small peat basins (c. 10-50 m diameter) were used to obtain fine spatial resolution pollen-stratigraphic records of Holocene vegetation and land-use history in upland West Glen Affric and adjacent lowland Kintail, north-western Scottish Highlands. These data provide evidence for remarkably diverse and dynamic early to mid-Holocene vegetational mosaic and sustained later Holocene upland land-use. While acidophilous Pinus sylvestris-Betula-Calluna vulgaris communities on lower hillslopes appear comparable with other areas of the Highlands, data from floodplain and alluvial fan sediments in West Affric indicate a greater woodland diversity. Betula-dominated alluvial woods included a species-rich mix of arboreal, fen, tall-herb and ruderal herbaceous taxa, with Pinus forming small populations, confined to marginal soils. Ulmus was an important component of the lowland Betula-Alnus woods. Spatial differences in soil forming processes, particularly nutrient and base status, played a primary role in determining community composition, structure, dynamics, species diversity and stability. Inferred climatic shifts during the mid-Holocene, initially to drier, more continental conditions, followed by increased oceanicity, are suggested to have made woodland communities increasingly vulnerable to low intensity grazing disturbance and anthropogenic interference during the later Neolithic and early Bronze Age. These stresses resulted in widespread woodland decline, including that of Pinus, with the spread of blanket peat and heath on poorer hillside soils, and grassland communities on alluvial sediment. Bronze Age agricultural expansion is followed by several phases of expansion and/or intensification, with sustained pastoral and arable activity in the lowlands and on small 'islands' of richer soils in the uplands. There is little evidence for abandonment and the longevity of agricultural activity, particularly cultivation, above 250 m OD clearly indicates that the unqualified assumption of upland marginality is inappropriate. The implications for the interpretation of land-use in the Highlands from conventional palynological and archaeological records are discussed. The level of spatial and temporal detail regarding the palaeoecology of plant communities and adaptive land management evident in the present study is not afforded by conventional pollen analyses. This suggests that fine-spatial resolution palynology has the potential to contribute previously unrecognised information at scales which are directly applicable to ecological and human understanding and which can be more successfully integrated with neoecological and archaeological research, fostering closer collaboration between the disciplines

Dung fungi as an indicator of large herbivore dynamics in peatlands

This study was supported by the Ecological Continuity Trust and the Quaternary Research Association.Coprophilous fungal spores (CFS) have gained prominence in paleoecology as a proxy for large herbivore dynamics. Dung availability is one of several factors that influences spore abundance so it is unclear how closely CFS levels track herbivore biomass. This uncertainty is particularly relevant in peat- and moorland, where grazing impacts are a recurring topic in paleoecology and source of tension in environmental management, and where the method has yet to be tested. The current study used three ecological and conservation grazingexperiments in UK peat- and moorland to study modern and recent historic relationships between grazing treatment and the abundance of three key CFS types and three pollen disturbance indicators. A total of 78 surface samples and 2 short peat cores were analyzed. Dispersal distances are estimated to range from < 10m to tens of meters, based on significantly lower CFS abundance in exclosed than grazed plots at two sites, and similar CFS trends over the last century in short peats cores located 80m apart at the third site. The CFS signal thus represents activity in the surrounding landscape, despite predominantly local dispersal. CFS abundance does not correspond with animal biomass when compared across the three sites, however, and pollen disturbance indicators in the peat cores matched recent historic grazing records more consistently than CFS abundance. Potential reasons for these mismatches are discussed. Quantitative inferences about large herbivore abundance from CFS in peatlands should therefore be made with caution and recommendations are madefor further testing of the method.PostprintPeer reviewe

Interdisciplinary research

Many messages emerging from scientific panels on the state of biodiversity, climate change and the planet emphasise the importance of greater integration between disciplines. But there’s no textbook to read before diving into interdisciplinary work. This guide is for researchers embarking on their first interdisciplinary project. It covers practical steps to take when conceiving, planning, or participating in an interdisciplinary project.Publisher PD

Red deer exhibit spatial and temporal responses to hiking activity

Funding: This project is funded through a joint James Hutton Institute & University of St Andrews collaborative PhD Studentship, the Carnegie Trust and the British Deer Society.Outdoor recreation has the potential to impact the spatial and temporal distribution of animals. We explore interactions between red deer Cervus elaphus and hikers along a popular hiking path in the Scottish Highlands. We placed camera traps in transects at different distances (25, 75 and 150 m) from the path to study whether distance from hiker activity influences the number of deer detected. We compared this with the detection of red deer in an additional, spatially isolated area (one km away from any other transects and the hiking path). We collected count data on hikers at the start of the path and explored hourly (red deer detection during daytime), daily, diurnal (day versus night) and monthly spatial distributions of red deer. Using generalized linear mixed models with forward model selection, we found that the distribution of deer changed with the hiking activity. We found that fewer red deer were detected during busy hourly hiking periods. We found that during daytime, more red deer were detected at 150 m than at 25 m. Moreover, during the day, red deer were detected at a greater rate in the isolated area than around the transects close to the path and more likely to be found close to the path at night. This suggests that avoidance of hikers by red deer, in this study area, takes place over distances greater than 75 m and that red deer are displaced into less disturbed areas when the hiking path is busy. Our results suggest that the impact of hikers is short-term, as deer return to the disturbed areas during the night.Publisher PDFPeer reviewe

Red deer behavioural response to hiking activity : a study using camera traps

With increasing levels of outdoor recreation activities, consequences for wildlife through interactions with recreationists are highly variable. Behavioural changes in wildlife are one potential consequence of interactions with outdoor recreationists. In ungulate populations, vigilance and flight responses are well-known antipredator behaviours, and an increase in their level indicates a more intense stress level which, ultimately, can have consequences for animal fitness. In Scotland, the geographical distribution of red deer (Cervus elaphus) overlaps greatly with areas used for popular outdoor activities such as hill walking. In this piece of research, we studied red deer time allocation, vigilance, and flight behaviours near a popular hiking path using camera traps. We positioned the cameras in transects at different distances (25, 75, and 150 m) from the path and recorded hiking activity using an automated people counter. Red deer behaviour was categorized from photo analysis as (1) no response (e.g. feeding and resting), (2) vigilant (i.e. upright head position), and (3) flight response. We also investigated demographic variables (group size and sex) and the direction of red deer movement relative to the trail. We used generalised linear mixed models to analyse behaviour in relation to the distance from the hiking track, hiking activity, time of the day, demographic, and environmental variables. We did not find an increase in vigilance or flight behaviour in relation to the distance from the hiking path or the hiking activity. These results suggest that red deer, in our study area, are habituated to the presence of hikers and may spatially avoid areas close to the hiking path instead of displaying cost-intensive behaviour (i.e. flight or vigilance behaviour).Publisher PDFPeer reviewe

Substantial stores of sedimentary carbon held in mid-latitude fjords

This work was supported by the Natural Environment Research Council [Grant Number: NE/L501852/1].Quantifying marine sedimentary carbon stocks is key to improving our understanding of longterm storage of carbon in the coastal ocean and to further constraining the global carbon cycle. Here we present a methodological approach which combines seismic geophysics and geochemical measurements to quantitatively estimate the total stock of carbon held within marine sediment. Through the application of this methodology to Loch Sunart a fjord on the west coast of Scotland, we have generated the first full sedimentary carbon inventory for a fjordic system. The sediments of Loch Sunart hold 26.9 ± 0.5 Mt of carbon split between 11.5 ± 0.2 Mt and 15.0 ± 0.4 Mt of organic and inorganic carbon respectively. These new quantitative estimates of carbon stored in coastal sediments are significantly higher than previous estimates. Through an area normalised comparison to adjacent Scottish peatland carbon stocks we have determined that these mid–latitude fjords are significantly more effective as carbon stores than their terrestrial counterparts. This initial work supports the concept that fjords are important environments for the burial and long-term storage of carbon and therefore should be considered and treated as unique environments within the global carbon cycle.Publisher PDFPeer reviewe

The application of resilience concepts in palaeoecology

The concept of resilience has become increasingly important in ecological and socio-ecological literature. With its focus on the temporal behaviour of ecosystems, palaeoecology has an important role to play in developing a scientific understanding of ecological resilience. We provide a critical review of the ways in which resilience is being addressed by palaeoecologists. We review ~180 papers, identifying the definitions or conceptualisations of ‘resilience’ that they use, and analysing the ways in which palaeoecology is contributing to our understanding of ecological resilience. We identify three key areas for further development. Firstly, the term ‘resilience’ is frequently defined too broadly to be meaningful without further qualification. In particular, palaeoecologists need to distinguish between ‘press’ vs. ‘pulse’ disturbances, and ‘ecological’ vs. ‘engineering’ resilience. Palaeoecologists are well placed to critically assess the extent to which these dichotomies apply in real (rather than theoretical) ecosystems, where climate and other environmental parameters are constantly changing. Secondly, defining a formal ‘response model’ - a statement of the anticipated relationships between proxies, disturbances and resilience properties - can help to clarify arguments, especially inferred causal links, since the difficulty of proving causation is a fundamental limitation of palaeoecology for understanding ecosystem drivers and responses. Thirdly, there is a need for critical analysis of the role of scale in ecosystem resilience. Different palaeoenvironmental proxies are differently able to address the various temporal and spatial scales of ecological change, and these limitations, as well as methodological constraints on inherently noisy proxy data, need to be explored and addressed.PostprintPeer reviewe

Spatial and temporal variations in interspecific interaction : impact of a recreational landscape

Anthropogenic activities, such as outdoor recreation, have the potential to change complex interactions between wildlife and livestock, with further consequences for the management of both animals, the environment, and disease transmission. We present the interaction amongst wildlife, livestock, and outdoor recreationists as a three-way interaction. Little is known about how recreational activities alter the interaction between herbivores in areas extensively used for recreational purposes. We investigate how hiking activity affects spatio-temporal co-occurrence between domestic sheep (Ovis aries) and red deer (Cervus elaphus). We used camera traps to capture the spatio-temporal distribution of red deer and sheep and used the distance from the hiking path as a proxy of hiking activity. We used generalized linear models to investigate the spatial distribution of sheep and deer. We analysed the activity patterns of sheep and deer and then calculated their coefficients of temporal overlap for each camera trap location. We compared these coefficients in relation to the distance from the hiking path. Finally, we used a generalized linear mixed-model to investigate which factors influence the spatio-temporal succession between deer and sheep. We do not find that sheep and red deer spatially avoid each other. The coefficient of temporal overlap varied with distance from the hiking trail, with stronger temporal co-occurrence at greater distances from the hiking trail. Red deer were more likely to be detected further from the path during the day, which increased the temporal overlap with sheep in these areas. This suggests that hiking pressure influences spatio-temporal interactions between sheep and deer, leading to greater temporal overlap in areas further from the hiking path due to red deer spatial avoidance of hikers. This impact of recreationists on the wildlife and livestock interaction can have consequences for the animals’ welfare, the vegetation they graze, their management, and disease transmission.Publisher PDFPeer reviewe

The vulnerability of tropical peatlands to oil and gas exploration and extraction

Funding: Leverhulme Trust (Grant Number(s): RPG-2018-306); UK Natural Environment Research Council (Grant Number(s): NE/R000751/1, NE/R016860/1, NE/V018760/1); Scottish Research Council/University of St Andrews.Tropical peatlands store globally significant quantities of carbon and are ecologically and culturally important, but little is known about their vulnerability to oil and gas exploration and extraction. Here, we analyse the exposure of tropical peatlands to the activities of the petroleum industry and review what is known about the sensitivity of peatlands to these activities. We find that 8.3% (107,000 km2) of the total area of tropical peatlands overlaps with a 30-km buffer area around oil and gas infrastructure. Major areas of overlap include the Sumatra Basin (Indonesia), the Niger Delta (Nigeria) and the Putumayo-Oriente-Marañón Basin (Peru/Ecuador/Colombia). Documented environmental impacts include deforestation and habitat loss associated with the exploration and development of oil fields, and contamination from spills of oil and produced water (well brine). Peatlands, and the ecosystem services they provide, are sensitive to these impacts due to unique aspects of their ecology and hydrology, the easy spread of contamination by flowing water, the long-term storage of contaminants in peat, and the slow degradation of oil under anoxic, waterlogged conditions. Given the potential negative consequences for human health, resource security, biodiversity, and carbon storage, we propose a research agenda to provide an improved evidence base to support effective governance.Publisher PDFPeer reviewe