Global distribution patterns of mycoheterotrophy

Environmental Biolog

Leaf economics and plant hydraulics drive leaf : wood area ratios

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this recordData accessibility: All data are archived and are available from the TRY plant trait data base: www.try-db.org (https://doi.org/10.1111/j.1365-2486.2011.02451.x).Biomass and area ratios between leaves, stems and roots regulate many physiological and ecological processes. The Huber value Hv (sapwood area/leaf area ratio) is central to plant water balance and drought responses. However, its coordination with key plant functional traits is poorly understood, which prevents developing trait-based prediction models. Based on theoretical arguments, we hypothesise that global patterns in Hv of terminal woody branches can be predicted from variables related to plant trait spectra, i.e., plant hydraulics and size and leaf economics. Using a global compilation of 1135 species-averaged Hv , we show that Hv varies over 3 orders of magnitude. Higher Hv are seen in short small-leaved low-SLA shrubs with low Ks in arid relative to tall large-leaved high-SLA trees with high Ks in moist environments. All traits depend on climate but climatic correlations are stronger for explanatory traits than Hv . Negative isometry is found between Hv and Ks , suggesting a compensation to maintain hydraulic supply to leaves across species. This work identifies the major global drivers of branch sapwood/leaf area ratios. Our approach based on widely available traits facilitates the development of accurate models of aboveground biomass allocation and helps predict vegetation responses to drought.Spanish Ministry of Economy and Competitiveness (MINECO)University of NottinghamSwedish Research Council Forma

The abundance of arbuscular mycorrhiza in soils is linked to the total length of roots colonized at ecosystem level

Arbuscular mycorrhizal fungi (AMF) strongly affect ecosystem functioning. To understand and quantify the mechanisms of this control, knowledge about the relationship between the actual abundance and community composition of AMF in the soil and in plant roots is needed. We collected soil and root samples in a natural dune grassland to test whether, across a plant community, the abundance of AMF in host roots (measured as the total length of roots colonized) is related to soil AMF abundance (using the neutral lipid fatty acids (NLFA) 16:1ω5 as proxy). Next-generation sequencing was used to explore the role of community composition in abundance patterns. We found a strong positive relationship between the total length of roots colonized by AMF and the amount of NLFA 16:1ω5 in the soil. We provide the first field-based evidence of proportional biomass allocation between intra-and extraradical AMF mycelium, at ecosystem level. We suggest that this phenomenon is made possible by compensatory colonization strategies of individual fungal species. Finally, our findings open the possibility of using AMF total root colonization as a proxy for soil AMF abundances, aiding further exploration of the AMF impacts on ecosystems functioning.Environmental Biolog

Microbiota in dung and milk differ between organic and conventional dairy farms

Organic farming is increasingly promoted as a means to reduce the environmental impact of artificial fertilizers, pesticides, herbicides, and antibiotics in conventional dairy systems. These factors potentially affect the microbial communities of the production stages (soil, silage, dung, and milk) of the entire farm cycle. However, understanding whether the microbiota representative of different production stages reflects different agricultural practices - such as conventional versus organic farming - is unknown. Furthermore, the translocation of the microbial community across production stages is scarcely studied. We sequenced the microbial communities of soil, silage, dung, and milk samples from organic and conventional dairy farms in the Netherlands. We found that community structure of soil fungi and bacteria significantly differed among soil types, but not between organic versus conventional farming systems. The microbial communities of silage also did not differ among conventional and organic systems. Nevertheless, the dung microbiota of cows and the fungal communities in the milk were significantly structured by agricultural practice. We conclude that, while the production stages of dairy farms seem to be disconnected in terms of microbial transfer, certain practices specific for each agricultural system, such as the content of diet and the use of antibiotics, are potential drivers of shifts in the cow's microbiota, including the milk produced. This may reflect differences in farm animal health and quality of dairy products depending on farming practices.Environmental Biolog

Mycorrhizal mycelium as a global carbon pool

For more than 400 million years, mycorrhizal fungi and plants have formed partnerships that are crucial to the emergence and functioning of global ecosystems. The importance of these symbiotic fungi for plant nutrition is well established. However, the role of mycorrhizal fungi in transporting carbon into soil systems on a global scale remains under-explored. This is surprising given that ∼75% of terrestrial carbon is stored belowground and mycorrhizal fungi are stationed at a key entry point of carbon into soil food webs. Here, we analyze nearly 200 datasets to provide the first global quantitative estimates of carbon allocation from plants to the mycelium of mycorrhizal fungi. We estimate that global plant communities allocate 3.93 Gt CO2e per year to arbuscular mycorrhizal fungi, 9.07 Gt CO2e per year to ectomycorrhizal fungi, and 0.12 Gt CO2e per year to ericoid mycorrhizal fungi. Based on this estimate, 13.12 Gt of CO2e fixed by terrestrial plants is, at least temporarily, allocated to the underground mycelium of mycorrhizal fungi per year, equating to ∼36% of current annual CO2 emissions from fossil fuels. We explore the mechanisms by which mycorrhizal fungi affect soil carbon pools and identify approaches to increase our understanding of global carbon fluxes via plant–fungal pathways. Our estimates, although based on the best available evidence, are imperfect and should be interpreted with caution. Nonetheless, our estimations are conservative, and we argue that this work confirms the significant contribution made by mycorrhizal associations to global carbon dynamics. Our findings should motivate their inclusion both within global climate and carbon cycling models, and within conservation policy and practice

Bacteriën en schimmels op melkveebedrijf in beeld

Environmental Biolog

Towards scalable estimation of plant functional diversity from Sentinel-2: in-situ validation in a heterogeneous (semi-)natural landscape

Environmental BiologyConservation Biolog