Résumé
Climate warming is expected to have large effects on ecosystems in part due to the temperature dependence of metabolism. The responses of metabolic rates to climate warming may be greatest in the tropics and at low elevations because mean temperatures are warmer there and metabolic rates respond exponentially to temperature (with exponents >1). However, if warming rates are sufficiently fast in higher latitude/elevation lakes, metabolic rate responses to warming may still be greater there even though metabolic rates respond exponentially to temperature. Thus, a wide range of global patterns in the magnitude of metabolic rate responses to warming could emerge depending on global patterns of temperature and warming rates. Here we use the Boltzmann–Arrhenius equation, published estimates of activation energy, and time series of temperature from 271 lakes to estimate long-term (1970–2010) changes in 64 metabolic processes in lakes. The estimated responses of metabolic processes to warming were usually greatest in tropical/low-elevation lakes even though surface temperatures in higher latitude/elevation lakes are warming faster. However, when the thermal sensitivity of a metabolic process is especially weak, higher latitude/elevation lakes had larger responses to warming in parallel with warming rates. Our results show that the sensitivity of a given response to temperature (as described by its activation energy) provides a simple heuristic for predicting whether tropical/low-elevation lakes will have larger or smaller metabolic responses to warming than higher latitude/elevation lakes. Overall, we conclude that the direct metabolic consequences of lake warming are likely to be felt most strongly at low latitudes and low elevations where metabolism-linked ecosystem services may be most affected.
Auteurs, date et publication :
Auteurs Benjamin M. Kraemer , Sudeep Chandra , Anthony I. Dell , Margaret Dix , Esko Kuusisto , David M. Livingstone , S. Geoffrey Schladow , Eugene Silow , Lewis M. Sitoki , Rashid Tamatamah , Peter B. McIntyre
Publication : Global Change Biology
Date : 2025
Volume : 23
Issue : 5
Pages : 1881-1890
Catégorie(s)
#INRAE #OLARésumé
Understanding the spatial distribution of aquatic microbial diversity and the underlying mechanisms causing differences in community composition is a challenging and central goal for ecologists. Recent insights into protistan diversity and ecology are increasing the debate over their spatial distribution. In this study, we investigate the importance of spatial and environmental factors in shaping the small protists community structure in lakes. We analyzed small protists community composition (beta-diversity) and richness (alpha-diversity) at regional scale by different molecular methods targeting the gene coding for 18S rRNA gene (T-RFLP and 454 pyrosequencing). Our results show a distance–decay pattern for rare and dominant taxa and the spatial distribution of the latter followed the prediction of the island biogeography theory. Furthermore, geographic distances between lakes seem to be the main force shaping the protists community composition in the lakes studied here. Finally, the spatial distribution of protists was discussed at the global scale (11 worldwide distributed lakes) by comparing these results with those present in the public database. UniFrac analysis showed 18S rRNA gene OTUs compositions significantly different among most of lakes, and this difference does not seem to be related to the trophic status.
Auteurs, date et publication :
Auteurs Cécile Lepère , Isabelle Domaizon , Najwa Taïb , Jean-François Mangot , Gisèle Bronner , Delphine Boucher , Didier Debroas
Publication : FEMS Microbiology Ecology
Date : 2025
Volume : 85
Issue : 1
Pages : 85-94
Catégorie(s)
#INRAE #OLAAuteurs, date et publication :
Auteurs Alexandre Baud , Jean-Philippe Jenny , Pierre Francus , Irene Gregory-Eaves
Publication : Journal of Paleolimnology
Date : 2025
Volume : 66
Issue : 4
Pages : 453-467
Catégorie(s)
#INRAE #OLAAuteurs, date et publication :
Auteurs Jessica Côte , Anthony Bouétard , Yannick Pronost , Anne-Laure Besnard , Maïra Coke , Fabien Piquet , Thierry Caquet , Marie-Agnès Coutellec
Publication : Environmental Pollution
Date : 2015
Volume : 205
Pages : 209-217
Catégorie(s)
#INRAE #PEARLAuteurs, date et publication :
Auteurs M.-A. Coutellec
Date : 2025
Catégorie(s)
#INRAE #PEARLAuteurs, date et publication :
Auteurs Bouetard A. , Hoede C. , Besnard A-L. , M. Collinet , Noirot C. , Lagadic L. , M.-A. Coutellec
Date : 2012
Catégorie(s)
#INRAE #PEARLAuteurs, date et publication :
Auteurs Francis Martin , Stephane Uroz , Samuel Dequiedt , Pierre-Alain Maron , Lionel Ranjard
Date : 2025
Volume : 1399
Pages : 55-60
Catégorie(s)
#Genosol #INRAERésumé
Many studies have focused on the impact of intense drought and rain events on soil functioning and diversity, but little attention has been paid to the response of microbial communities to non-extreme soil moisture variations. However, small fluctuations of soil water content represent a common situation that ought to be examined before understanding and deciphering the impact of extreme events. Here, we tested the impact of a decrease in average soil water content and small water content fluctuations in non-extreme conditions on microbial community composition and C mineralisation rate of a temperate meadow soil. Two soil microcosm sets were incubated at high and low constant moisture and a third set was subjected to 4 short dry–wet cycles between these two soil moistures. No robust change in bacterial community composition, molecular microbial biomass, and fungal:bacterial ratio were associated with soil water content change. On the contrary, the fungal community composition rapidly alternated between states corresponding to the high and low levels of soil moisture content. In addition, gross C mineralisation was correlated with soil moisture, with a noteworthy absence of a Birch effect (C over-mineralisation) during the wetting. This study suggests that some fungal populations could coexist by occupying different moisture niches, and high fungal community plasticity would classify them as more sensitive indicators of soil moisture than bacteria. Moreover, under non-stressed conditions, the community composition did not affect metabolic performance so a future decrease in average soil moisture content should not result in a supplemental loss in soil carbon stocks by a Birch effect.
Auteurs, date et publication :
Auteurs A. Kaisermann , P. A. Maron , L. Beaumelle , J. C. Lata
Publication : Applied Soil Ecology
Date : 2025
Volume : 86
Pages : 158-164
Catégorie(s)
#Genosol #INRAERésumé
Background: Europe has warmed more than the global average (land and ocean) since pre-industrial times, and is also projected to continue to warm faster than the global average in the twenty-first century. According to the cli‑mate models ensemble projections for various climate scenarios, annual mean temperature of Europe for 2071–2100 is predicted to be 1–5.5 °C higher than that for 1971–2000. Climate change and elevated C O2 concentration are antici‑pated to affect grassland management and livestock production in Europe. However, there has been little work done to quantify the European-wide response of grassland to future climate change. Here we applied ORCHIDEE-GM v2.2, a grid-based model for managed grassland, over European grassland to estimate the impacts of future global change.
Results: Increases in grassland productivity are simulated in response to future global change, which are mainly attributed to the simulated fertilization effect of rising CO2. The results show significant phenology shifts, in particular an earlier winter-spring onset of grass growth over Europe. A longer growing season is projected over southern and southeastern Europe. In other regions, summer drought causes an earlier end to the growing season, overall reducing growing season length. Future global change allows an increase of management intensity with higher than current potential annual grass forage yield, grazing capacity and livestock density, and a shift in seasonal grazing capacity. We found a continual grassland soil carbon sink in Mediterranean, Alpine, North eastern, South eastern and Eastern regions under specific warming level (SWL) of 1.5 and 2 °C relative to pre-industrial climate. However, this carbon sink is found to saturate, and gradually turn to a carbon source at warming level reaching 3.5 °C.
Conclusions: This study provides a European-wide assessment of the future changes in productivity and phenology of grassland, and their consequences for the management intensity and the carbon balance. The simulated produc‑tivity increase in response to future global change enables an intensification of grassland management over Europe. However, the simulated increase in the interannual variability of grassland productivity over some regions may reduce the farmers’ ability to take advantage of the increased long-term mean productivity in the face of more frequent, and more severe drops of productivity in the future.
Auteurs, date et publication :
Auteurs Jinfeng Chang , Philippe Ciais , Nicolas Viovy , Jean-François Soussana , Katja Klumpp , Benjamin Sultan
Publication : Carbon Balance and Management
Date : 2025
Volume : 12
Issue : 1
Catégorie(s)
#ACBB #ACBB Theix #INRAERésumé
An ectomycorrhiza is a multitrophic association between a tree root, an ectomycorrhizal fungus, free-living fungi and the associated bacterial communities. Enzymatic activities of ectomycorrhizal root tips are therefore result of the contribution from different partners of the symbiotic organ. However, the functional potential of the fungus-associated bacterial communities remains unknown. In this study, a collection of 80 bacterial strains randomly selected and isolated from a soil-ectomycorrhiza continuum (oak-Scleroderma citrinum ectomycorrhizas, the ectomycorrhizosphere and the surrounding bulk soil) were characterized. All the bacterial isolates were identified by partial 16S rRNA gene sequences as members of the genera Burkholderia, Collimonas, Dyella, Mesorhizobium, Pseudomonas, Rhizobium and Sphingomonas. The bacterial strains were then assayed for beta-xylosidase, beta-glucosidase, N-acetyl-hexosaminidase, beta-glucuronidase, cellobiohydrolase, phosphomonoesterase, leucine-aminopeptidase and laccase activities, chitin solubilization and auxin production. Using these bioassays, we demonstrated significant differences in the functional distribution of the bacterial communities living in the different compartments of the soil-ectomycorrhiza continuum. The surrounding bulk soil was significantly enriched in bacterial isolates capable of hydrolysing cellobiose and N-acetylglucosamine. In contrast, the ectomycorrhizosphere appeared significantly enriched in bacterial isolates capable of hydrolysing glucopyranoside and chitin. Notably, chitinase and laccase activities were found only in bacterial isolates belonging to the Collimonas and Pseudomonas genera. Overall, the results suggest that the ectomycorrhizal fungi favour specific bacterial communities with contrasting functional characteristics from the surrounding soil.
Auteurs, date et publication :
Auteurs S. Uroz , P. E. Courty , J. C. Pierrat , M. Peter , M. Buee , M. P. Turpault , J. Garbaye , P. Frey-Klett
Publication : Microbial Ecology
Date : 2013
Volume : 66
Issue : 2
Pages : 404-415