Research

My research is divided between theoretical and applied statistics, with particular focus on spatial data problems.

Journal articles

Computing maps of forest structural diversity: Aggregate late

point patterns
forests
biodiversity
summary statistics
remote sensing
Example data: https://github.com/antiphon/point-pattern-examples
Aug 26, 2025
Tuomas Rajala, Annika Kangas, Mari Myllymäki

Optimizing the regeneration of spruce-dominated stands suffering from Heterobasidion root rot in Finland

forests
Bayesian modelling
Heterobasidion root rot is a destructive fungal disease causing extensive damage in conifer forests throughout the Northern hemisphere. The effective spreading of the causal…
Feb 13, 2025
Eero Holmström, Juha Honkaniemi, Anssi Ahtikoski, Tuomas Rajala, Jarkko Hantula, Tuula Piri, Juha Heikkinen, Susanne Suvanto, Tapio Räsänen, Juha-Antti Sorsa, Kirsi Riekki, Henna Höglund, Aleksi Lehtonen, Mikko Peltoniemi

Reindeer shape soil methanogenic and methanotrophic communities in subarctic fen peatlands, with a minor impact on methane emissions — A field study

soil sciences
Bayesian modelling
SEM
Laboratory and field studies with other grazer species suggest that reindeer (Rangifer tarandus L.) grazing on northern peatlands could shape the peat soil microbial…
Sep 22, 2024
Raija Laiho, Petri Salovaara, Päivi Mäkiranta, Krista Peltoniemi, Timo Penttilä, Tuomas Rajala, Jenni Hultman, Mika Korkiakoski, Hannu Fritze

Does multidimensional distance matter? Perceptions and acceptance of wind power

social sciences
In addressing long-term climate and energy challenges with wind energy, the acceptance of wind power is in a key role. Here, we systematically emphasize the several…
Nov 6, 2023
Eija Pouta, Tuomas Rajala, Erkki Mäntymaa, Katja Kangas, Juha Hiedanpää

Visualizing the Wavenumber Content of a Point Pattern

point patterns
spectral analysis
Spatial point patterns are a commonly recorded form of data in ecology, medicine, astronomy, criminology, epidemiology and many other application fields. One way to…
Nov 1, 2023
Jake P Grainger, Tuomas Rajala, David J Murrell, Sofia Olhede

What is the Fourier Transform of a Spatial Point Process?

point patterns
spectral analysis
This paper determines how to define a discretely implemented Fourier transform when analysing an observed spatial point process. To develop this transform we answer four…
Aug 1, 2023
Tuomas Rajala, Sofia Olhede, Jake P Grainger, David J Murrell

Improving Detection of Changepoints in Short and Noisy Time Series with Local Correlations: Connecting the Events in Pixel Neighbourhoods

time-series analysis
remote sensing
NFI
Code in the form of an R-package available at Github as package tjdc, see dedicated page
May 16, 2023
Tuomas Rajala, Petteri Packalen, Mari Myllymäki, Annika Kangas

Fine-root biomass production and its contribution to organic matter accumulation in sedge fens under changing climate

soil sciences
Climate change may affect the carbon sink function of peatlands through warming and drying. Fine-root biomass production (FRBP) of sedge fens, a widespread peatland habitat…
Feb 1, 2023
Rabbil Bhuiyan, Päivi Mäkiranta, Petra Straková, Hannu Fritze, Kari Minkkinen, Timo Penttilä, Tuomas Rajala, Eeva-Stiina Tuittila, Raija Laiho

Tests for isotropy in spatial point patterns – A comparison of statistical indices

point patterns
anisotropy
statistical power
Code: All of the summary statistics are implemented in Kdirectional
Nov 25, 2022
Tuomas Rajala, Claudia Redenbach, Aila Särkkä, Martina Sormani

Identifying territories using presence-only citizen science data: An application to the Finnish wolf population

wildlife
point patterns
citizen science
Citizens, community groups and local institutions participate in voluntary biological monitoring of population status and trends by providing species data e.g. for…
Oct 1, 2022
Santeri Karppinen, Tuomas Rajala, Samu Mäntyniemi, Ilpo Kojola, Matti Vihola

Age-dependence of stand biomass in managed boreal forests based on the Finnish National Forest Inventory data

NFI
forests
Information on carbon stocks and the rate of carbon accumulation is needed to harness the climate change mitigation potential of boreal forests. While previous studies have…
Oct 21, 2021
Anna Repo, Tuomas Rajala, Helena M Henttonen, Aleksi Lehtonen, Mikko Peltoniemi, Juha Heikkinen
 

Seasonal and diel activity patterns of the endangered taiga bean goose (Anser fabalis fabalis) during the breeding season, monitored with camera traps

wildlife
Taiga bean goose (Anser fabalis fabalis) is an endangered subspecies that breeds sporadically in remote habitats in the arctic and boreal zones. Due to its elusive…
Jun 15, 2021
Milaja Nykänen, Hanny Pöysä, Sari Hakkarainen, Tuomas Rajala, Juho Matala, Merki Kunnasranta

Assessing local trends in indicators of ecosystem services with a time series of forest resource maps

time-series analysis
remote sensing
NFI
Related R-package: Contextual Mann-Kendall test, ConMK (github)
Sep 14, 2020
Matti Katila, Tuomas Rajala, Annika Kangas

Second order analysis of geometric anisotropic point processes revisited

point patterns
anisotropy
Various methods for directional analysis of spatial point patterns have been introduced in the literature. In this paper, we formulate a unifying framework for methods based…
Aug 1, 2020
Martina Sormani, Claudia Redenbach, Aila Särkkä, Tuomas Rajala

A Bayesian hierarchical point process model for epidermal nerve fiber patterns

point patterns
epidermal nerve fibers
Bayesian modelling
We introduce the Thomas process in a Bayesian hierarchical setting as a model for point pattern data with a nested structure. This model is applied to a nerve fiber data set…
May 1, 2019
Claes Andersson, Tuomas Rajala, Aila Särkkä

A review on anisotropy analysis of spatial point patterns

point patterns
anisotropy
A spatial point pattern is called anisotropic if its spatial structure depends on direction. Several methods for anisotropy analysis have been introduced in the literature.…
Dec 1, 2018
Tuomas Rajala, Claudia Redenbach, Aila Särkkä, Martina Sormani

When do we have the power to detect biological interactions in spatial point patterns?

point patterns
statistical power
  1. Uncovering the roles of biotic interactions in assembling and maintaining species-rich communities remains a major challenge in ecology. In plant communities…

Oct 1, 2018
Tuomas Rajala, Sofia Olhede, David Murrell

Growth of a common planktonic diatom quantified using solid medium culturing

phytoplankton
The ability to grow on solid culture medium is a pre-requisite for a successful microbial genetic model organism. Skeletonema marinoi, a bloom-forming, planktonic marine…
Jul 27, 2018
Olga Kourtchenko, Tuomas Rajala, Anna Godhe

Detecting Multivariate Interactions in Spatial Point Patterns with Gibbs Models and Variable Selection

point patterns
biodiversity
Gibbs models
Code: R-package PenGE
Apr 23, 2018
Tuomas Rajala, David Murrell, Sofia Olhede

Optimization of a high-throughput phenotyping method for chain-forming phytoplankton species

phytoplankton
Modern equipment facilitates phenotyping of hundreds of strains of unicellular organisms by culturing and monitoring growth in microplates. However, in the field of…
Nov 27, 2017
Susanna Gross, Olga Kourtchenko, Tuomas Rajala, Björn Andersson, Luciano Fernandez, Anders Blomberg, Anna Godhe

A three-dimensional anisotropic point process characterization for pharmaceutical coatings

point patterns
anisotropy
While epidermal nerve fiber (ENF) data have been used to study the effects of small fiber neuropathies through the density and the spatial patterns of the ENFs, little…
May 24, 2017
Henrike Häbel, Tuomas Rajala, Mariagrazia Marucci, Catherine Boissier, Katja Schladitz, Claudia Redenbach, Aila Särkkä

Estimating geometric anisotropy in spatial point patterns

point patterns
anisotropy
Anisotropy in stationary spatial point patterns is investigated. We develop a two-stage non-parametric method for quantifying geometric anisotropy arising for example when…
Jan 21, 2016
Tuomas Rajala, Aila Särkkä, Claudia Redenbach, Martina Sormani

Hierarchical models for epidermal nerve fiber data

point patterns
epidermal nerve fibers
Bayesian modelling
While epidermal nerve fiber (ENF) data have been used to study the effects of small fiber neuropathies through the density and the spatial patterns of the ENFs, little…
Dec 9, 2015
Claes Andersson, Tuomas Rajala, Aila Särkkä

Variational Bayes Approach for Classification of Points in Superpositions of Point Processes

point patterns
Bayesian modelling
We investigate the problem of classifying superpositions of spatial point processes. In particular, we are interested in realizations formed as a superposition of a regular…
Dec 9, 2015
Tuomas Rajala, Claudia Redenbach, Aila Särkkä, Martina Sormani

Bayesian analysis of a Gibbs hard-core point pattern model with varying repulsion range

point patterns
Bayesian modelling
Gaussian processes
A Bayesian solution is suggested for the modelling of spatial point patterns with inhomogeneous hard-core radius using Gaussian processes in the regularization. The key…
Mar 1, 2014
Tuomas Rajala, Antti Penttinen

A family of spatial biodiversity measures based on graphs

summary statistics
point patterns
biodiversity
While much research in ecology has focused on spatially explicit modelling as well as on measures of biodiversity, the concept of spatial (or local) biodiversity has been…
Jun 1, 2012
Tuomas Rajala, Janine Illian
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