Termite mounds (TMs) mediate biogeochemical processes with global relevance, such as turnover of the important greenhouse gas methane (CH4). However, the complex internal and external morphology of TMs impede an accurate quantitative description. Here we present two novel field methods, photogrammetry (PG) and cross-section image analysis, to quantify TM external and internal mound structure of 29 TMs of three termite species. Photogrammetry was used to measure epigeal volume (VE), surface area (AE) and mound basal area (AB) by reconstructing 3D models from digital photographs, and compared against a water-displacement method and the conventional approach of approximating TMs by simple geometric shapes. To describe TM internal structure, we introduce TM macro- and micro-porosity (θM and θµ), the volume fractions of macroscopic chambers, and microscopic pores in the wall material, respectively. Macro-porosity was estimated using image analysis of single TM cross-sections, and compared against full x-ray tomography (CT) scans of 17 TMs. For these TMs we present complete pore fractions to assess species-specific differences in internal structure. The PG method yielded VE nearly identical to a water-displacement method, while approximation of TMs by simple geometric shapes led to errors of 4–200 %. Likewise, using PG substantially improved the accuracy of CH4 emission estimates by 10–50 %. Comprehensive CT scanning revealed that investigated TMs have species-specific ranges of θM and θµ, but similar total porosity. Image analysis of single TM cross-sections produced good estimates of θM for species with thick walls and evenly distributed chambers. The new image-based methods allow rapid and accurate quantitative characterisation of TMs to answer ecological, physiological and biogeochemical questions. The PG method should be applied when measuring greenhouse-gas emissions from TMs to avoid large errors from inadequate shape approximations.
Termite mound surface mesh models
3-D surface mesh models of termite mounds generated by photogrammetry using SfM algorithms with the software Agisoft Photoscan Standard.
PG_models.zip
Termite-mound cross-section images
RGB and binary images of termite mound cross sections to determine full (closed) and chambers (holes) cross-section area for estimating mound macro-porosity
cross-sections.zip
CT scans binary images
CT-scan binary images of termite mounds to determine full (closed) volume and volume fractions of chambers (holes) and wall material (solid) with a supplied Matlab script
CT_binary.zip
DICOM images termite mound Mn1
Raw DICOM image files of CT-scanned termite mound Mn1
NauerPA_201806_termite-mound_Mn1-2016_CT-scan_raw.zip
DICOM images termite mound Mn2
Raw DICOM image files of CT-scanned termite mound Mn2
NauerPA_201806_termite-mound_Mn2-2016_CT-scan_raw.zip
DICOM images termite mound Mn4
Raw DICOM image files of CT-scanned termite mound Mn4
NauerPA_201806_termite-mound_Mn4-2016_CT-scan_raw.zip
DICOM images termite mound Mn6
Raw DICOM image files of CT-scanned termite mound Mn6
NauerPA_201806_termite-mound_Mn6-2016_CT-scan_raw.zip
DICOM images termite mound Mn8
Raw DICOM image files of CT-scanned termite mound Mn8
NauerPA_201806_termite-mound_Mn8-2016_CT-scan_raw.zip
DICOM images termite mound Mn9
Raw DICOM image files of CT-scanned termite mound Mn9
NauerPA_201806_termite-mound_Mn9-2016_CT-scan_raw.zip
DICOM images termite mound Ms1
Raw DICOM image files of CT-scanned termite mound Ms1
NauerPA_201806_termite-mound_Ms1-2016_CT-scan_raw.zip
metadata
Metadata on termite mounds and physical properties analysis
Data and scripts for image/data analysis
Data and R script on termite mound physical parameters; Matlab script and ImageJ/Fiji macros used for image analysis of termite mound CT scans and cross sections.
data_scripts.zip
Ms1DICOM images termite mound Ms3
Raw DICOM image files of CT-scanned termite mound Ms3
NauerPA_201806_termite-mound_Ms3-2016_CT-scan_raw.zip
DICOM images termite mound Ms5
Raw DICOM image files of CT-scanned termite mound Ms5
NauerPA_201806_termite-mound_Ms5-2016_CT-scan_raw.zip
DICOM images termite mound Ms6
Raw DICOM image files of CT-scanned termite mound Ms6
NauerPA_201806_termite-mound_Ms6-2016_CT-scan_raw.zip
DICOM images termite mound Ms7
Raw DICOM image files of CT-scanned termite mound Ms7
NauerPA_201806_termite-mound_Ms7-2016_CT-scan_raw.zip
DICOM images termite mound Tp1
Raw DICOM image files of CT-scanned termite mound Tp1
NauerPA_201806_termite-mound_Tp1-2016_CT-scan_raw.zip
DICOM images termite mound Tp2
Raw DICOM image files of CT-scanned termite mound Tp2
NauerPA_201806_termite-mound_Tp2-2016_CT-scan_raw.zip
DICOM images termite mound Tp3
Raw DICOM image files of CT-scanned termite mound Tp3
NauerPA_201806_termite-mound_Tp3-2016_CT-scan_raw.zip
DICOM images termite mound Tp4
Raw DICOM image files of CT-scanned termite mound Tp4
NauerPA_201806_termite-mound_Tp4-2016_CT-scan_raw.zip
DICOM images termite mound Tp5
Raw DICOM image files of CT-scanned termite mound Tp5
NauerPA_201806_termite-mound_Tp5-2016_CT-scan_raw.zip
DICOM images termite mound Tp6
Raw DICOM image files of CT-scanned termite mound Tp6
NauerPA_201806_termite-mound_Tp6-2016_CT-scan_raw.zip