Investigating the effects of soil microclimate on mesofauna communities in a temperate rainforest

Abstract

Temperate rainforests are highly biodiverse ecosystems, with much of that biodiversity found within
the soil. Soil mesofauna, specifically mites and Collembola, play essential roles in nutrient cycling,
decomposition, and the regulation of soil communities, contributing to essential ecosystem services.
These communities are shaped by small-scale climate conditions, particularly temperature and
moisture in the soil, yet the influence of natural microclimate variability on whole mesofauna
communities remains poorly understood. This study investigates the effect of soil microclimate on
mesofauna communities in a UK temperate rainforest. Fifty soil samples were collected across ten
plots in Ausewell Woods, Dartmoor. Microclimate variables were continuously recorded using in-situ
dataloggers at each sampling point, and over 29,000 mesofauna individuals were extracted and
identified using a semi-automated workflow combining manual identification with computer vision.
A custom YOLOv8 object detection model was trained and applied to digitised images of fauna to
support fast, high-throughput identification. Soil temperature had a significant negative relationship
with total mesofauna abundance, community composition and on two Collembola orders,
Entomobryomorpha and Poduromorpha. No significant relationship was found between soil
moisture and community metrics, likely due to low moisture conditions during the month prior to
sampling. This study highlights the vulnerability of mesofauna to increased temperatures, with
implications for soil ecosystem function and stability as global temperatures rise. It also
demonstrates the potential for computer vision to assist in addressing the bottleneck in research
caused by invertebrate identification. Research incorporating seasonal sampling and additional
environmental variables would further the understanding of the drivers and interactions shaping
understudied soil mesofauna communities.

Date of Award	30 Sept 2025
Original language	English
Awarding Institution	University of Bristol
Supervisor	Hannah M Griffiths (Supervisor) & Tommaso Jucker (Supervisor)