University of Oulu

Aalto, J., Tyystjärvi, V., Niittynen, P., Kemppinen, J., Rissanen, T., Gregow, H., & Luoto, M. (2022). Microclimate temperature variations from boreal forests to the tundra. Agricultural and Forest Meteorology, 323, 109037.

Microclimate temperature variations from boreal forests to the tundra

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Author: Aalto, Juha1,2; Tyystjärvi, Vilna1,2; Niittynen, Pekka2;
Organizations: 1Finnish Meteorological Institute, P.O. Box 503, Helsinki FI-00101, Finland
2Department of Geosciences and Geography, University of Helsinki, P.O. Box 64, Gustaf Hällströmin katu 2a, Helsinki FI-00014, Finland
3The Geography Research Unit, University of Oulu, P.O. Box 8000, Oulu FI-90014, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 8.2 MB)
Persistent link:
Language: English
Published: Elsevier, 2022
Publish Date: 2022-12-14


Microclimate varies greatly over short horizontal and vertical distances, and timescales. This multi-level heterogeneity influences terrestrial biodiversity and ecosystem functions by determining the ambient environment where organisms live in. Fine-scale heterogeneity in microclimate temperatures is driven by local topography, land and water cover, snow, and soil characteristics. However, their relative influence over boreal and tundra biomes and in different seasons, has not been comprehensively quantified. Here, we aim to (1) quantify temperature variations measured at three heights: soil (-6 cm), near-surface (15 cm) and air (150 cm), and (2) determine the relative influence of the environmental variables in driving thermal variability. We measured temperature at 446 sites within seven focus areas covering large macroclimatic, topographic, and ecosystem gradients (tundra, mires, forests) of northern Europe. Our data, consisting of over 60 million temperature readings during the study period of 2019/11–2020/10, reveal substantial thermal variability within and across the focus areas. Near-surface temperatures in the tundra showed the greatest instantaneous differences within a given focus area (32.3 °C) while the corresponding differences for soil temperatures ranged from 10.0 °C (middle boreal forest) to 27.1 °C (tundra). Instantaneous differences in wintertime air temperatures were the largest in the tundra (up to 25.6°C, median 4.2 °C), while in summer the differences were largest in the southern boreal forest (13.1°C, median 4.8°C). Statistical analyses indicate that monthly-aggregated temperature variations in boreal forests are closely linked to water bodies, wetlands, and canopy cover, whereas in the tundra, variation was linked to elevation, topographic solar radiation, and snow cover. The results provide new understanding on the magnitude of microclimate temperature variability and its seasonal drivers and will help to project local impacts of climate change on boreal forest and tundra ecosystems.

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Series: Agricultural and forest meteorology
ISSN: 0168-1923
ISSN-E: 1873-2240
ISSN-L: 0168-1923
Volume: 323
Article number: 109037
DOI: 10.1016/j.agrformet.2022.109037
Type of Publication: A1 Journal article – refereed
Field of Science: 1171 Geosciences
Funding: JA and HG acknowledges Academy of Finland Flagship funding (Grant No. 337552), and JA and VT acknowledge the funding by the Faculty of Science, University of Helsinki (project MICROCLIM, grant no. 7510145). JK was funded by the Arctic Interactions at the University of Oulu and Academy of Finland (Grant No. 318930, Profi 4). TR was funded by the Doctoral programme in Geosciences at the University of Helsinki. PN was funded by the Nessling Foundation and the Kone foundation. We want to thank all field work assistants and the staff of Värriö, Hyytiälä and Kilpisjärvi research stations. We acknowledge funding from Nordenskiöld samfundet, Tiina and Antti Herlin foundation, Oskar Öflunds stiftelse, and Maa- ja vesitekniikan tuki ry.
Academy of Finland Grant Number: 318930
Detailed Information: 318930 (Academy of Finland Funding decision)
Dataset Reference: The raw microclimate data and code to preprocess these data are available in the study-area-specific Github repositories ( The preprocessed data and code used in this study are available in a Github repository ( and a static version of this repository will be deposited and openly published in Zenodo upon acceptance for publishing.
Copyright information: © 2022 The Authors. This is an open access article under the CC BY license (