Beetles and the development of Thorne Moors, SE Yorkshire, UK

Abstract

This project investigates the potential of terrestrial Coleoptera for monitoring and anticipating change in a modied raised mire ecosystem, so as to inform ongoing ecological restoration and to aid conservation management in building resilience for an uncertain future. It also investigates the potential for ecological restoration — primarily rewetting of drained and cutover peats — to conserve and restore peatland Coleoptera to areas where they have been been removed by human exploitation. The primary data for this study is an original survey of terrestrial Coleoptera, conducted over a period of seven months in 2015, and resulting in the Identification of ~12,000 individual beetles, from ~250 species. This study has identified three Research Challenges, the first of which is how to distinguish environmental signals from stochastic noise (RC 1). This is addressed by placing modern ecological data in a long-term context derived from palaeoecology. As ecologists have better access to the volume and quality of data required to produce quantitative models, whereas palaeoecologists often rely on inductive reasoning to produce environmental reconstructions based on interpretations of limited data, this study addresses a second Research Challenge; namely how to link the past to the present (RC 2) and bridge the methodological gap between palaeoecology and ecology. This study meets this challenge by placing c. 10,000 years of change of the Thorne Moors raised mire system in south east Yorkshire, England, within a panarchic framework and conceptualising change as a series of adaptive cycles, progress through which is affected by multiple drivers acting and interacting over different spatial and temporal scales. A narrative approach to environmental reconstruction is utilised, drawing on the exceptional body of palaeoecological and historical information available for the study area. Panarchy provides a theoretical framing for the complex cross-scale interactions acting across time and space up to the present day and beyond. It is accessible to palaeoecologists, ecologists and conservation practitioners alike and helps us to anticipate future directions of change. Environmental disasters and near-misses of recent years foreshadow the impending threat to socio-ecological systems posed by climate change, not least drained peatlands which are threatened with destruction from ever-frequent wildres. Thus a final Research Challenge has been identified as that of linking the academy to practitioners (RC 3). This is addressed by producing a toolkit that can guide the design of time- and cost-effective monitoring of terrestrial Coleoptera, which has been built using extensive palaeoecological and historical information, combined with analysis of modern Coleopteran data and first-hand field experience gained in the process of conducting the 2015 terrestrial Coleopteran survey.

Chapter 1 introduces key concepts such as ecological restoration, panarchy and Coleoptera as indicators in monitoring, and also introduces the study site, Thorne Moors, SE Yorkshire, England. Chapter 2 reviews the extensive palaeoecological and historical information available on Thorne Moors and uses the framework of panarchy to construct a narrative of complex cross-scale interactions between small and fast, and large and slow cycles of change from the end of the Devensian Glaciation c. 10,000 years ago, up to the present day. Chapter 3 returns to the panarchic phases of Thorne Moors outlined in Chapter 2, and examines the palaeoentomological literature to understand how these phases relate to the beetle assemblages and the changes they undergo. In the process of doing so, the study collates existing, albeit limited, knowledge of the niche preferences and traits of Coleopteran groups and species, and examines how these might relate to their fates today; whether they "declined" (thought to be extinct in the Humberhead Levels), "survived" (persist, but in precarious numbers or reliant on threatened habitats/features) or thrived (evidence, possibly anecdotal, that they have increased in numbers and/or have wider distributions). Chapter 4 outlines the methodology for the 2015 terrestrial Coleopteran survey, which considered five compartments of the moors. Chapter 5 presents the results of the terrestrial survey and considers the biases that may have affected the results. Chapter 6 analyses the results of the 2015 survey using long-term perspectives gained earlier and presents a novel application of a machine learning method — term frequency-inverse document frequency (TF-IDF) — to identify species which characterise each of the study compartments, each with its own historical contingency and semi-independent adaptive cycle. The chapter then uses Quantitative Comparative Analysis of human impacts to understand how these species came to characterise each compartment. Chapter 7 focuses on the peatland and wetland species which are absent from the 2015 Coleopteran survey, but which are recorded as having been present in the past. A concept of cryptic diversity is used to distinguish between those that species are "hidden" (i.e. present on Thorne Moors but not recorded in the survey) from those that, circumstantial evidence suggests, are "dark" (i.e. are extinct in the region of the Humberhead Levels). This demonstrates how study of "cryptic" species can provide an additional perspective on species presence data collected by Coleopteran monitoring, which can complement discussion of why some species are present with that of why some species are absent. Chapter 8 considers the interactions between people and nature in relation to conservation ecology and ecological restoration. In doing so, it firstly contemplates the current state of peatland restoration in the UK and the barriers to the rewetting of endangered peatlands — specically neoliberal economics and its relationship to the most recent framing of conservation, "Nature-based Solutions". Secondly it argues for the importance of training and careers in ecosystem restoration monitoring that go beyond monitoring more easily monetiseable measures relating to hydrology and peat accumulation. Finally a practitioner's toolbox is presented for the utilisation of terrestrial Coleoptera in monitoring modied raised mire restoration and response to climate change.