Johan van den Hoogen

Last Name

van den Hoogen

First Name

Johan

ORCID

0000-0001-6624-8461

Organisational unit

09625 - Crowther, Thomas Ward (ehemalig) / Crowther, Thomas Ward (former)

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Publications 1 - 10 of 49

The biogeography of relative abundance of soil fungi versus bacteria in surface topsoil
Yu, Kailiang; van den Hoogen, Johan; Wang, Zhiqiang; et al. (2022)
Earth System Science Data
Fungi and bacteria are the two dominant groups of soil microbial communities worldwide. By controlling the turnover of soil organic matter, these organisms directly regulate the cycling of carbon between the soil and the atmosphere. Fundamental differences in the physiology and life history of bacteria and fungi suggest that variation in the biogeography of relative abundance of soil fungi versus bacteria could drive striking differences in carbon decomposition and soil organic matter formation between different biomes. However, a lack of global and predictive information on the distribution of these organisms in terrestrial ecosystems has prevented the inclusion of relative abundance of soil fungi versus bacteria and the associated processes in global biogeochemical models. Here, we used a global-scale dataset of >3000 distinct observations of abundance of soil fungi versus bacteria in the surface topsoil (up to 15 cm) to generate the first quantitative and high-spatial-resolution (1 km2) explicit map of soil fungal proportion, defined as fungi/fungi + bacteria, across terrestrial ecosystems. We reveal striking latitudinal trends where fungal dominance increases in cold and high-latitude environments with large soil carbon stocks. There was a strong nonlinear response of fungal dominance to the environmental gradient, i.e., mean annual temperature (MAT) and net primary productivity (NPP). Fungi dominated in regions with low MAT and NPP and bacteria dominated in regions with high MAT and NPP, thus representing slow vs. fast soil energy channels, respectively, a concept with a long history in soil ecology. These high-resolution models provide the first steps towards representing the major soil microbial groups and their functional differences in global biogeochemical models to improve predictions of soil organic matter turnover under current and future climate scenarios. Raw datasets and global maps generated in this study are available at https://doi.org/10.6084/m9.figshare.19556419 (Yu, 2022).
ForestTemp – Sub-canopy microclimate temperatures of European forests
Haesen, Stef; Lembrechts, Jonas J.; De Frenne, Pieter; et al. (2021)
Global Change Biology
Ecological research heavily relies on coarse-gridded climate data based on standardized temperature measurements recorded at 2 m height in open landscapes. However, many organisms experience environmental conditions that differ substantially from those captured by these macroclimatic (i.e. free air) temperature grids. In forests, the tree canopy functions as a thermal insulator and buffers sub-canopy microclimatic conditions, thereby affecting biological and ecological processes. To improve the assessment of climatic conditions and climate-change-related impacts on forest-floor biodiversity and functioning, high-resolution temperature grids reflecting forest microclimates are thus urgently needed. Combining more than 1200 time series of in situ near-surface forest temperature with topographical, biological and macroclimatic variables in a machine learning model, we predicted the mean monthly offset between sub-canopy temperature at 15 cm above the surface and free-air temperature over the period 2000-2020 at a spatial resolution of 25 m across Europe. This offset was used to evaluate the difference between microclimate and macroclimate across space and seasons and finally enabled us to calculate mean annual and monthly temperatures for European forest understories. We found that sub-canopy air temperatures differ substantially from free-air temperatures, being on average 2.1 degrees C (standard deviation +/- 1.6 degrees C) lower in summer and 2.0 degrees C higher (+/- 0.7 degrees C) in winter across Europe. Additionally, our high-resolution maps expose considerable microclimatic variation within landscapes, not captured by the gridded macroclimatic products. The provided forest sub-canopy temperature maps will enable future research to model below-canopy biological processes and patterns, as well as species distributions more accurately.
The pace of life for forest trees
Bialic-Murphy, Lalasia; McElderry, Robert M.; Esquivel-Muelbert, Adriane; et al. (2024)
Science
Tree growth and longevity trade-offs fundamentally shape the terrestrial carbon balance. Yet, we lack a unified understanding of how such trade-offs vary across the world's forests. By mapping life history traits for a wide range of species across the Americas, we reveal considerable variation in life expectancies from 10 centimeters in diameter (ranging from 1.3 to 3195 years) and show that the pace of life for trees can be accurately classified into four demographic functional types. We found emergent patterns in the strength of trade-offs between growth and longevity across a temperature gradient. Furthermore, we show that the diversity of life history traits varies predictably across forest biomes, giving rise to a positive relationship between trait diversity and productivity. Our pan-latitudinal assessment provides new insights into the demographic mechanisms that govern the carbon turnover rate across forest biomes.
Ways forward for Machine Learning to make useful global environmental datasets from legacy observations and measurements
Hengl, Tomislav; Routh, Devin; van den Hoogen, Johan (2022)
Nature Communications
Advances in geospatial and Machine Learning techniques for large datasets of georeferenced observations have made it possible to produce model-based global maps of ecological and environmental variables. However, the implementation of existing scientific methods (especially Machine Learning models) to produce accurate global maps is often complex. Tomislav Hengl (co-founder of OpenGeoHub foundation), Johan van den Hoogen (researcher at ETH Zurich), and Devin Routh (Science IT Consultant at the University of Zurich) shared with Nature Communications their perspectives for creators and users of these maps, focusing on the key challenges in producing global environmental geospatial datasets to achieve significant impacts.
State of knowledge of soil biodiversity
Scow, Kate; Bardgett, Richard D.; Pennock, Dan; et al. (2020)
ForestClim—Bioclimatic variables for microclimate temperatures of European forests
Haesen, Stef; Lembrechts, Jonas J.; De Frenne, Pieter; et al. (2023)
Global Change Biology
Microclimate research gained renewed interest over the last decade and its importance for many ecological processes is increasingly being recognized. Consequently, the call for high-resolution microclimatic temperature grids across broad spatial extents is becoming more pressing to improve ecological models. Here, we provide a new set of open-access bioclimatic variables for microclimate temperatures of European forests at 25 × 25 m2 resolution.
Tree species composition governs urban phenological responses to warming
Wu, Zhaofei; Zohner, Constantin; Zhou, Yuyu; et al. (2025)
Nature Communications
Urban environments are typically warmer than surrounding rural areas, providing a unique setting for studying phenological responses to climate warming. Phenological differences between urban and rural trees are driven by local climate and species composition. Yet, the extent to which species composition influences phenological responses to urbanization remains poorly understood. To address this, we combine manipulative experiments, satellite-derived phenology data, and georeferenced tree occurrence records. Our findings show that, across Northern Hemisphere cities, differences in the temperature sensitivity of spring phenology between urban and rural areas are largely driven by urban-rural variation in species composition, surpassing the effects of preseason temperature. This pattern is particularly pronounced in Asian cities, where urban areas exhibit 0.74 ± 0.24 days/°C higher temperature sensitivity than rural areas. In-depth analyses using experiments and high-resolution satellite imagery from Beijing further demonstrate species-specific phenological responses to urbanization, with urban-dominant species exhibiting higher temperature sensitivity in urban environments compared to rural ones. These findings show that both interspecific variation in temperature sensitivity and species-specific responses to urbanization contribute to the pronounced impact of species composition on urban-rural phenological patterns. Our study underscores the importance of considering species composition when studying phenological responses to climate warming, especially in urban contexts.
Land-use- and climate-mediated variations in soil bacterial and fungal biomass across Europe and their driving factors
Siles, José A.; Vera, Alfonso; Díaz-López, Marta; et al. (2023)
Geoderma
Elucidating contents and drivers of soil bacterial and fungal biomass in contrasting land uses and climates at European scale is useful to define appropriate policies for the conservation of the ecosystem services that soil microorganisms provide. Here, we aimed to (i) quantify and compare bacterial and fungal biomass in 513 European soils collected from three different land uses (forests, grasslands, and croplands) and climates (arid, temperate, and cold) through analysis of fatty acid methyl esters; (ii) model the factors controlling soil bacterial and fungal biomass; and (iii) investigating levels of bacterial and fungal biomass in cropland soils cultivated with three important crop types in Europe: cereals, oil-producing crops, and orchards. Bacterial biomass decreased with land use in the following order: grasslands > croplands > forests and was found to be the highest in temperate environments. Similar patterns were found for biomass of Gram-positive and Gram-negative bacteria and Actinobacteria. Soil fungal biomass was greater in forests than in croplands and grasslands and was favoured by colder environments. The fungi to bacteria ratio (F/B) decreased as follows: forests > croplands > grasslands, with soils in colder climates showing greater F/B ratios in croplands and forests. Soil texture, soil organic carbon, and nitrogen were shown to directly drive bacterial and fungal biomass. The biomass of the different microbial groups was not influenced by the crop type when only croplands were considered. Fungi appear to be more susceptible to agricultural soil use than bacteria. Moreover, agricultural use of soil seems to buffer the effect of harsh climatic conditions on soil bacterial biomass. The present study improves our understanding of the combined effects of land use and climate on soil bacterial and fungal biomass across Europe.
Macroevolutionary decline in mycorrhizal colonization and chemical defense responsiveness to mycorrhization
Formenti, Ludovico; Iwanycki Ahlstrand, Natalie; Hassemer, Gustavo; et al. (2023)
iScience
Arbuscular mycorrhizal fungi (AMF) have evolved associations with roots of 60% plant species, but the net benefit for plants vary broadly from mutualism to parasitism. Yet, we lack a general understanding of the evolutionary and ecological forces driving such variation. To this end, we conducted a comparative phylogenetic experiment with 24 species of Plantago, encompassing worldwide distribution, to address the effect of evolutionary history and environment on plant growth and chemical defenses in response to AMF colonization. We demonstrate that different species within one plant genus vary greatly in their ability to associate with AMF, and that AMF arbuscule colonization intensity decreases monotonically with increasing phylogenetic branch length, but not with concomitant changes in pedological and climatic conditions across species. Moreover, we demonstrate that species with the highest colonization levels are also those that change their defensive chemistry the least. We propose that the costs imposed by high AMF colonization in terms of reduced changes in secondary chemistry might drive the observed macroevolutionary decline in mycorrhization.
The Genome of Peronospora belbahrii Reveals High Heterozygosity, a Low Number of Canonical Effectors, and TC-Rich Promoters
Thines, Marco; Sharma, Rahul; Rodenburg, Sander Y. A.; et al. (2020)
Molecular Plant-Microbe Interactions

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Johan van den Hoogen

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