Biology subjects

Aalto, J.

Publications and source records attributed to Aalto, J..

5 recordsLinked to original sources

bioRxiv2026

Interactive effects of land use change and climate drive the decline of a threatened boreal forest orchid in Finland

Land use and climate change are two of the greatest threats to biodiversity globally. However, their interactive effects remain poorly understood. In the boreal forest biome, where species are experiencing increasing pressures from forest management and climate change, improved understanding of these effects is urgently needed. Here, we assess the impacts of forest loss and both baseline and changing late spring climatic conditions on the extinction probability of a threatened boreal forest orchid, Calypso bulbosa. We use a unique dataset consisting of 1,006 C. bulbosa occurrence sites located in Finland, historical aerial images, and climatic data spanning the last 60 years. Our results reveal that forest loss, at the local rather than landscape-scale, and both the site-specific baseline climatic conditions and their change over time influence the extinction probability of C. bulbosa. These effects were mainly interactive with greater temporal increase in rainfall ameliorating and greater baseline rainfall exacerbating the negative effect of forest loss on the species persistence. Furthermore, greater baseline snow depth ameliorated this negative effect. We also found some statistical support for independent effects of baseline thermal sum and its change over time, but their ecological relevance was interpreted as minor. Overall, our results align with the expectation that forest loss can modify the exposure of forest-dependent species to climatic conditions, thus altering their vulnerability to climate change.

ecology↗

bioRxiv2024

A Gridded Microclimate Dataset from a Sub-Arctic Biodiversity Hotspot in Finland

Microclimate measurements are crucial for explaining and predicting functions and patterns in nature, yet the availability of microclimate data often poses a challenge. This study introduces a dataset comprising 63 spatially continuous microclimate surfaces for the Kilpisjarvi region in northwestern Finland. The study region is a biodiversity hotspot for arctic-alpine flora and fauna and one of the most extensively investigated regions in Northern Europe. The data were gathered through a collaborative network of microclimate loggers, encompassing 430 measurement locations that comprehensively cover the 300 km2 landscape under study. We employed predominantly well-performing Random Forest models to project microclimate variables across the study area at a 3-metre spatial resolution. The high-resolution and extensive spatial coverage of the dataset facilitates examination of microclimate characteristics and variability across this sub-Arctic region, providing a valuable resource for both theoretical and applied research, as well as for biodiversity conservation.

ecology↗

bioRxiv2023

Integrating leaf gas exchange and chlorophyll fluorescence to reveal the long-term regulation of photosynthesis in situ

Understanding the diurnal and seasonal regulation of photosynthesis is an essential step in quantifying and modeling the impact of the environment on plant function. Although the dynamics of photosynthesis have been widely investigated in terms of CO2 exchange measurements, a more comprehensive view can be obtained when combining gas exchange and chlorophyll fluorescence (ChlF) measurements. However, such integrated measurements have been so far restricted to short term analysis using portable systems that combine IRGA and PAM-ChlF techniques. Here we introduce and demonstrate a new method for integrated, long-term and in situ measurements of leaf gas exchange and ChlF, based on an autonomous gas exchange system and a new miniature PAM- fluorometer. The method is used to simultaneously track the dynamics of the light and carbon reactions of photosynthesis at a 20-minute resolution in leaves of silver birch during summer time. The potential of the method is initially demonstrated using the ratio between electron transport and net assimilation (ETR/ANET). We successfully captured the diurnal patterns in the ETR/ANET during summer time, including a drastic increase in ETR/ANET upon a high-temperature period. We suggest that these measurements can provide valuable data to model and quantify the regulation of leaf photosynthesis in situ. HighlightWe introduce new integrated measurements to help resolve the seasonal and diurnal dynamics of photosynthesis regulation by combining long-term simultaneous measurements of gas exchange and chlorophyll fluorescence in field conditions.

plant biology↗

bioRxiv2019

Woody plants constructing tundra soils

In tundra, woody plants are expanding towards higher latitudes and altitudes due to increasingly favourable climatic conditions. Their expansion may also occur through increases in the coverage and height of the plants. These shifts may cascade further across the ecosystem, such as in the foundations of tundra: that is, in the soils. Yet, little is known about the effects woody plants have on local soil conditions. Here, we examined if the coverage and height of woody plants affect the growing-season soil moisture and temperature as well as soil organic carbon stocks. We carried out a field observation study in a dwarf shrub-dominated tundra and built a hierarchical model. We found that, after controlling for other possible factors influencing woody plants and soil conditions (namely, topography, snow, and the overall plant coverage), the coverage of woody plants inversely correlated with all three soil conditions. Yet, we found no link between the woody plant height to the soil variables. This indicates that woody plants affect local soil conditions in various ways, depending upon whether their expansion occurs though the growth of coverage or their height. Nevertheless, woody plants likely alter the very ground of the entire tundra system and feedback into the global climate system through the water, energy, and carbon cycles of tundra.

ecology↗

bioRxiv2019

Snow is an important control of plant community functional composition

The functional composition of plant communities is a critical modulator of climate change impacts on ecosystems, but it is not a simple function of regional climate. In the Arctic tundra, where climate change is proceeding the most rapidly, communities have not shifted their trait composition as predicted by spatial temperature-trait relationships. Important causal pathways are thus missing from models of trait composition change. Here, we study causes of plant community functional variation in a tundra landscape. We consider the community weighted means of plant vegetative height, as well as two traits related to the leaf economic spectrum. Specifically, we model their responses to locally measured summer air temperature, snow conditions, and soil resource levels. For each of the traits we also quantify the importance of intraspecific trait variation (ITV) for between-community functional differences and trait-environment matching. Our study shows that in a tundra landscape 1) snow is the most influential abiotic variable affecting functional composition, 2) vegetation height is under weak local environmental control, whereas leaf economics is under strong local environmental control, 3) the relative magnitude of ITV differs between traits, and 4) ITV is not very consequential for community-level trait-environment relationships.

ecology↗