Jessie Moyses, a PhD Candidate at the Queensland University of Technology, has been provided with a grant to assist with her project aiming to explore how biodiversity-focused farm-level management interventions influence wild pollinators and natural enemies, and the relationships between management choices, landscape context, bird and arthropod diversity and agri-food production outcomes.
Project Summary
Biodiversity loss is occurring globally (Newbold et al., 2015). The impact of local biodiversity loss on ecosystem functioning is well understood, but the impact of such losses on the delivery of multiple ecosystem services has only recently been established (Le Provost et al., 2023). Aboveground regulating services, particularly pollination and pest suppression, are amongst the most sensitive ecosystem services to changes in biodiversity, and recent global syntheses revealed that these biodiversity-mediated services are critical to both crop production (Dainese et al., 2019; Emmerson et al., 2016) and ecosystem resilience (Oliver et al., 2015). However, long-term surveys have revealed that the animals providing pest control services and pollination (e.g. bats, birds, some insects) are declining worldwide (Potts et al., 2010; Zhou et al., 2023), and that agricultural land clearing and management practices are key drivers of this crisis (Dicks et al., 2021; Rodger et al., 2021). These declines could impact wild plant diversity, ecosystem health, food security, and human wellbeing (Kremen et al., 2002; Regan et al., 2015). We urgently need to find ways to preserve biodiversity-mediated ecosystem services to recover foundational plant-animal interactions linking primary producers to consumers across all types of terrestrial ecosystems.
Research and management to mitigate biodiversity decline in agri-food landscapes is currently limited to a few taxa (e.g., honey bees) and is spatially biased to Northern and Western Europe (Sánchez-Bayo & Wyckhuys, 2019; Wagner, 2020). In these studies, the positive effects of landscape-level restoration on native species are well researched (Bullock et al., 2001; Pywell et al., 2015). Positive outcomes for some groups of native species (i.e., birds) in response to restoration in agricultural landscapes has also been demonstrated in temperate woodlands in Australia (Lindenmayer, 2022). However, our ability to conserve biodiversity alongside agricultural production requires deeper understanding of the impacts of land management at farm scale. Farm management interventions such as pollinator habitat management (e.g. interrow or field edge plantings), crop diversification, agroforestry and integrated pest management have so far demonstrated mixed outcomes for biodiversity and food production (Nicholson et al., 2017; Venturini et al., 2017). A key research gap is to identify the management interventions with the greatest potential to co-benefit biodiversity and food production in Australia, and where to implement these interventions. With increasing frequency and severity of climate change-related shocks facing significant food production areas, and the impact and spread of pests such as varroa mite, recently established on Australia’s east coast (Albertazzi et al., 2021; Kremen & Miles, 2012; Rako et al., 2023), management strategies are urgently needed to better support biodiversity in agri-food landscapes.
This study is part of a PhD project. The PhD chapter I am applying for aims to explore: (i) how biodiversity-focused farm-level management interventions influence wild pollinators and natural enemies (arthropods and birds); and (ii) the relationships between management choices, landscape context, bird and arthropod diversity and agri-food production outcomes. This project will contribute positively to conservation of biodiversity in Australian temperate agricultural landscapes by identifying:
- the management interventions or activities that promote biodiversity at the farm level;
- the location, scale and timing of farm management to best support the maintenance and addition of habitat and resource requirements for biodiversity; and
- the situations in which farm management interventions are likely to co-benefit biodiversity and the delivery of biodiversity-based ecosystem services.
In 2024-2025 (year applying for funding), I will conduct my study on Gumbaynggirr Country, the NSW Mid-north coast. The mid-North coast is an important food bowl for several horticultural crops in Australia, including berries, avocados, bananas and macadamia nuts. The region has also been severely affected by intense rainfall and floods in recent years (DPI, 2020). I hypothesise that pollinator and pest diversity and abundance, and relatedly, pollination and pest control services, will be higher in contexts where management activities maintain or increase habitat for wild pollinators and natural enemies (Nicholson et al., 2017). Similarly, I hypothesise that growers who manage pollinators, natural enemies and their habitat in a positive way will receive more positive services from biodiversity (e.g. insectivorous birds putting downward pressure on crop pests) than disservices (e.g. frugivorous birds causing fruit damage), as found by Gonthier et al. (2019) on Californian strawberry farms. By grouping bird fauna according to different guilds (e.g. food preferences) and potential for ecosystem service provision (e.g. pest suppression), I will characterise how bird diversity varies between sites, with different levels of arthropod pests, and with crop phenology. I will also investigate how relationships between bird activity and fruit production are mediated by landscape-level land-use, vegetation cover and concurrent management activities.
Methods
Field work will take place across 15 raspberry farms on the NSW Mid-north Coast. Sites are located from Macksville to Corindi Beach. My team have already selected suitable study sites via existing working relationships with growers. Farms are located at least 5 km apart from one another to ensure independence. To account for temporal variation in crop visitation, fieldwork will occur over the four production “seasons” of the year: fallow (prior to growing season); greening (no flowers), flowering, fruiting. Data will be collected from two locations at each farm: i) within a raspberry orchard, and ii) within the nearest natural/semi natural habitat patch within 2 km of the orchard. Animal ethics approval has been granted for this project (AE 2024-8229-17412).
Point count surveys of birds
I will conduct four sets of observational point-count surveys to complement acoustic monitoring of birds and estimate numbers of birds at each farm. During each visit, I will complete two twenty-minute point count surveys at each of the two farm sites, identifying birds by sight using binoculars and/or by call. Each site will be surveyed once in the morning and once in the late afternoon per visit (these two surveys will complete one survey round).
Arthropod surveys
I will conduct 15-minute walking transects along orchard rows to survey arthropod species compositions at each site. I will walk transects slowly, recording all arthropods observed and their location (e.g., flying, leaf, stem, flower – corolla, flower – reproductive), collecting individuals if necessary for identification (Hall et al., 2020). Berry orchards will be surveyed twice per survey round. Arthropods will be classified using existing pest survey guides and pollinator expertise to calculate metrics of pollinator, pest, and natural enemy abundance and diversity at each site.
Farm management and crop production
To understand differences in farm management activities occurring at the study sites, property owners will be surveyed about their management activities (specifically those potentially affecting bird activity). This will include orchard tilling or soil management, use of chemical inputs or integrated pest management, use of managed pollinators, mowing within and around orchards and non-crop vegetation (e.g., pollinator reservoirs). At each site during each trip, a vegetation survey will be conducted to determine the availability of habitat for natural pollinators and wild enemies, consisting of (a) flower cover percentage (visually estimated at ten 50 x 50 cm squares along the arthropod transect (Pardo et al., 2023); and (b) botanical composition (i.e. plant diversity). During the harvesting season, I will collect a random sample of fruit from each orchard site to calculate fruit size and quality using established methods.
Bird call monitoring
To track the presence, activity and potential ecosystem service provision (pollination and pest suppression) of bird species within and around raspberry orchards, I will deploy one passive acoustic detector (Audiomoth v1.2) within an orchard and one within the nearest natural habitat at each farm (Kross et al., 2020). Each recorder would be set to record for four hours each day (two hours each at morning and dusk for bird calls). I will process and analyse bird call data using software program Raven Pro and BirdNet analyser (Kahl et al., 2021). Data will be validated by listening to sound files and comparing results from observational point count survey data.
Statistical modelling approach
I will statistically model the relationships between on-farm management practices, arthropod diversity or abundance (pollinator, pest, or natural enemy) and bird diversity and abundance/activity, grouped by ecosystem function (e.g., insectivore, nectivore) and berry quality. Structural equation models and/or synchronicity models will be used to interrogate correlations between management interventions and the dependent variables and to understand how interactions change with co-variates such as season and weather (Burian et al., 2023; Cusack et al., 2019).