Woodland soundscapes: Investigating new methods for monitoring landscapes

Biodiversity is an important provider of ecosystem services. There is a sense of urgency running through the scientific community regarding its protection and conservation. This urgency is fuelled by a wealth of research into the effects of habitat destruction, intensive agriculture, destructive industries (such as mining and oil exploration) and the insidious threat of climate change. It might reasonably be suggested that the biodiversity crisis we are facing today is in large part due to a lack of regulation around human-activities with regard to biodiversity impacts. In order to impose regulations, protecting biodiversity has been incentivised through various governmental and non-profit private-sector certification initiatives that aim to minimise the negative impacts that industry can have on the environment. Agri-environment schemes are largely governmental initiatives that aim to enhance the biodiversity and societal values of farmland. Timber certification initiatives, such as the Forest Stewardship Council, promote woodland management that takes into account the economic, environmental and social aspects of forestry with equal measure. Protection and enhancement of biodiversity is integral to achieving the environmental aims of certification. However, several studies have highlighted that many schemes (notably agri-environment schemes and some timber certification schemes) ultimately fall short of their projected targets, which is often due to a lack of suitable monitoring with regard to biodiversity. This is unsurprising since biodiversity monitoring is not a straightforward process. Many considerations need to be made when choosing suitable indicators of ecosystem health such as whether to measure species diversity or functional diversity. But perhaps one of the biggest issues is the ability of landowners and managers to contribute to efficient, objective, standardised data collection.

Acoustic monitoring offers a means of producing unbiased data that can be analysed objectively and stored indefinitely. With significant advances in hardware and software technologies, the proliferation of acoustic monitoring is evident in the scientific literature.The field of soundscape ecology was in many respects borne out of these technological advances. It has since been usurped by the newer field of ecoacoustics (I use these two terms interchangeably throughout this thesis). Ecoacoustics offers a range of soundscape analytical techniques that aim to understand the spectral and temporal composition of the soundscape. As such a number of acoustic indices can be used to measure different facets of acoustic diversity. This study offers an overview of the current literature in bioacoustics and ecoacoustics. It applies several of these indices to studying the soundscape of Forest Stewardship Council certified plantation forests in the UK. Specifically it investigates the soundscape in relation to habitat and landscape metrics and explores temporal variation in acoustic activity. It offers insights into the relationship between man-made/machine noise (technophony) and biological sounds (biophony) and suggests future directions for research and large-scale monitoring of habitats. Finally it provides a set of instructions on how to build an automated recording unit using readily available parts and provides links to necessary software and guidance on types of hardware available. The key findings indicate that the use of acoustic indices for monitoring landscapes could be a useful tool. Clear relationships were observed between forest structure and stand age, and vegetation structure, with acoustic diversity in Thetford forest over two consecutive years. Although these relationships were not clear in Bedgebury forest, the effects of landscape structure were statistically significant, particularly when using automated recording units. Road proximity had a strong influence on the soundscape in all study sites. And the use of

ecoacoustic methods to explore this offers an insight into a new means of investigating the impact of roads on acoustic biodiversity. The development of a low-cost automated recording unit is a significant contribution to the field of soundscape ecology in terms of encouraging participation by the non-governmental organisation (NGO) sector. Likewise, the use of a handheld recording unit and the application of traditional ecological survey methods provide evidence that soundscape/ecoacoustic studies that yield interesting, informative and biologically meaningful results can be done on a relatively low budget. As such this thesis offers a significant contribution to the field of soundscape ecology in terms of both data and logistics. It may be particularly relevant to researchers on a limited budget and/or the NGO and citizen science sector.