Sequence of plant responses to droughts of different timescales: lessons from holm oak (Quercus ilex) forests
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Tree physiology, forest structure and site-specific factors interact to determine the response of forests to recurring annual droughts, however, the increasing frequency of extreme droughts is making Mediterranean forests vulnerable. Picture shows Quercus ilex forests standing on the slopes of the sacred Montserrat mountain. Photo by Lluís Comas

 

The functional traits of plants in regions of the world with a Mediterranean climate have been shaped to tolerate periods of water deficit. These species are adapted to summer droughts but may not be able to cope with future increases in drought intensity, duration, and/or frequency.

In a new study published in Plant Ecology & Diversity researchers review the mechanisms and traits of drought resistance and recovery of the holm oak (Quercus ilex), which they propose as a model species for Mediterranean-type ecosystems. The aim of the study was to understand the differences and links between the responses of Q. ilex to summer droughts, extreme droughts, and long-term drought experiments. A main goal was to provide an integral picture of drought responses across organizational and temporal scales for identifying the most relevant processes that are likely to contribute to determining the future of Mediterranean vegetation. Evidence from long-term drought experiments showed that acclimation processes from the molecular (e.g. epigenetic changes) to the ecosystem level (e.g. reductions in stand density) mitigate the effects of drought.

Changes in leaf morphology and hydraulics, leaf-to-shoot allometry, and root functioning are among the key mechanisms for overcoming increasing drought. The duration of drought determines its severity in terms of canopy loss and stem mortality. Although Q. ilex can vigorously resprout after such episodes, its resilience may be subsequently reduced. In the future, higher frequency of return of extreme droughts will challenge thus the capacity of these forests to recover. The insights provided by this review of the complex interplay of processes that determine the response of trees to droughts of different duration, intensity, and frequency will also help to understand the likely responses of other resprouting angiosperms in seasonally dry ecosystems that share similar functional traits with Q. ilex.

“The limits of plasticity in primary and secondary growth in relation to future drier and warmer conditions may be determinants for the persistence of some populations in their current structure and function”, said Dr. Adrià Barbeta from CSIC-CREAF.

“We recommend that future research should keep on addressing the combined effect of consecutive extreme droughts and drier average conditions on the structure and function of plant communities, but with a special emphasis on the resilience after crown damage and on the access to the vital long-lasting deep water pools”, said Prof. Josep Peñuelas from CSIC-CREAF.

Citation: Barbeta, A., Peñuelas, J. 2016. Sequence of plant responses to droughts of different timescales: lessons from holm oak (Quercus ilex) forests. Plant Ecology & Diversity, 9:4, 321-338, doi: 10.1080/17550874.2016.1212288

Future climate change will affect plants and soil differently
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Changes of aboveground net primary production and soil respiration in response to drought indicated that wet systems had an overall risk of increased loss of C but drier systems did not. Photo by: Pixabay

 

In a new study published in the Nature journal Scientific Reports, researchers have found that soil carbon loss is more sensitive to climate change compared to carbon taken up by plants. In drier regions, soil carbon loss decreased but in wetter regions soil carbon loss increased. This could result in a positive feedback to the atmosphere leading to an additional increase of atmospheric CO2 levels.

Scientists analysed data from seven climate change experiments across Europe to show how European shrubland plant biomass and soil carbon loss is affected by summer drought and year-around warming.

The research was conducted by a group of European and American scientists including Marc Estiarte and Josep Peñuelas from CSIC-CREAF.

The authors showed that soil carbon loss is most responsive to change in soil water. Soil water plays a critical role in wet soils where water logging limits decomposition processes by soil biota resulting in a build-up of soil carbon as peat. Drying of the soil removes this limitation resulting in soil carbon loss. In contrast in drier soils, reduced rainfall reduces soil water below the optimum for soil biota resulting in a decrease in soil carbon loss.

Most of the earth’s terrestrial carbon is stored in soil. The world’s soil carbon stocks are estimated to be circa 2000 gigatonnes (1 gigatonne = 1 000 000 000 000 kilograms) of carbon. The researchers showed that drought decreases and increases soil carbon more predictably than warming.

Dr Sabine Reinsch, the first author on the paper and a Soil Ecologist at the Centre for Ecology & Hydrology in Bangor, said, “This cross European study enabled us, for the first, time to investigate plant and soil responses to climate change beyond single sites.

“Putting ecosystem responses to climate change into the wider context of natural climate gradients helps us to understand the observed responses of plants and soils better.”

Professor Penuelas, the Head of the Global Ecology Unit CREAF-CSIC and co-author on the paper, Prof Claus Beier and Prof. Bridgette Emmet, as senior authors of the study commented that “The study highlights and illustrates new and fundamental understanding related to the response of ecosystems to climate change.

“By conducting the same experiment at different moisture and temperature conditions across the European continent, it has become clear and visible how the pressure from climate change factors may act differently, and sometimes even opposite, across these conditions”.

“These differences are important for our overall assessment of future ecosystem responses to climate change, but the study also shows that they can be understood and to some extent predicted.” “These results emphasize how sensitive soil processes such as soil respiration are to environmental change. “

Dr Marc Estiarte, researcher at Spanish research centre CREAF-CSIC and co-author on the paper, said, “In contrast to the soils, reducing precipitation was not a threat to plant productivity in wetter sites, and in the drier sites plants resisted proportionally more than in intermediate sites, whose aboveground productivity was shown more sensitive. This illustrates the clear difference in sensitivity of the soils compared to the plants across the climate gradient.”

The new paper in Scientific Reports considers plant and soil responses to drought and warming only across European shrublands. There are several other biomes in the world where plant and soil responses to climate change could be different.

“Understanding the responses of plants and soils in other biomes will provide a better understanding of climate change and the effects on global plant and soil interactions and the feedbacks to climate”, said Prof. Josep Penuelas from CREAF-CSIC Barcelona.

Paper reference

Reinsch, S. Estiarte M., Penuelas J. et al. ‘Shrubland primary production and soil respiration diverge along European climate gradient,’ Scientific Reports. Published online 3 March 2017. DOI: 10.1038/srep43952

The paper is available as an open access document via this URL: www.nature.com/articles/srep43952

Pharmaceuticals and Personal-Care Products in Plants
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Pharmaceuticals and personal-care products reach plants predominantly from the use of reclaimed wastewater for irrigation. Photo by Pixabay

 Pharmaceutical and personal-care products (PPCPs) for human and animal use are increasingly released into the environment.

Plants act as excellent tracers of global pollution because they are present in almost all areas of the planet and accumulate chemical compounds present in the atmosphere, in the water with which they are irrigated, and in the soil on which they grow.

PPCP removal from plants for waste water treatment is incomplete, and the dispersal of these compounds into the environment and accumulation in plants mostly occurs from irrigating with reused water and from the application of biosolids and manure to land.

In a featured article in the journal Trends in Plant Science, UVIC and CREAF-CSIC researchers highlighted the potential of plants as biomonitors of PPCPs in the environment and the risk that the dietary intake of these PPCP-contaminated plants could have on the entire biosphere including on human health, even at low concentrations.

“Plants accumulate PPCP at concentrations that can be toxic to plants, plant microbiota, and soil microorganisms and thus affect nutrient cycling, food webs and ecosystem functioning. Furthermore, the risk to humans from dietary intake of these PPCP-contaminated plants (mostly crops) is uncertain but warrants deep consideration”, said Dr. Mireia Bartrons from Universitat de Vic, Barcelona.

“Further attention has recently been given to the effects of human and veterinary antibiotics. They dramatically affect the structure and function of soil microbial communities and promote the emergence of multidrug-resistant human pathogens that increasingly threaten successful anti-biotic treatment of bacterial infections”, said Prof. Josep Penuelas from CREAF-CSIC Barcelona.

Citation: Bartrons, M., Peñuelas, J. 2017. Pharmaceuticals and Personal-Care Products in Plants. Trends in Plant Science, (2017) 22, Issue 3, 194–203. doi: 10.1016/j.tplants.2016.12.010.

Successful 3rd Annual Paris Meeting!

From the 1st to the 3rd of February, we met in Pierre et Marie Curie University, in Paris, to gather together, share results and advance phosphorus-related science!

You can download our presentations here!

Three days of intense collaboration among the different imbalance-P groups, left us some pictures that we want to share with you.

See you all during the 4th Annual Meeting!

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Phosphorus accumulates faster than nitrogen globally in freshwater ecosystems under anthropogenic impacts

Water2_Pexels_Jan17

Underwater image of a lake. Photo by Pexels

Human activities have drastically accelerated Earth’s major biogeochemical cycles, altering the the nitrogen (N) and phosphorus (P) cycles.

Combined effects of cumulative nutrient inputs and biogeochemical processes that occur in freshwater under anthropogenic eutrophication could lead to myriad shifts in N:P stoichiometry in global freshwater ecosystems, but this was not yet well-assessed.

In a new study in the journal Ecology Letters researchers from Peking University and CREAF-CSIC evaluated the characteristics of N and P stoichiometries in bodies of freshwater and their herbaceous macrophytes across human-impact levels, regions and periods.

Freshwater and its macrophytes had higher N and P concentrations and lower N:P ratios in heavily than lightly human-impacted environments, further evidenced by spatiotemporal comparisons across eutrophication gradients. N and P concentrations in freshwater ecosystems were positively correlated and N:P ratio was negatively correlated with population density in China.

“Our findings indicate that anthropogenic eutrophication might thus shift aquatic ecosystems from a state of predominant P limitation to being potentially limited or co-limited by N, or by other factors such as light, especially in rapidly developing regions such as China” said Zhengbing Yan, researcher from Peking University.

“These results indicate a faster accumulation of P than N in human-impacted freshwater ecosystems, which could have large effects on the trophic webs and biogeochemical cycles of estuaries and coastal areas by freshwater loadings, and reinforces the importance of rehabilitating these ecosystems”, said Prof. Josep Penuelas from CREAF-CSIC Barcelona.

Citation: Yan, Z., Han, W., Penuelas, J., Sardans, J., Elser, J.J., Du, E., Fang, J. 2016. Phosphorus accumulates faster than nitrogen globally in freshwater ecosystems under anthropogenic impacts. Ecology Letters 19, (2016), 1237-1246. doi: 10.1111/ele.12658

Josep Peñuelas entrevistat al magazín 7 dies, d’El 9 tv

Josep Peñuelas, was interviewed on January 13th at 9tv, in “7 dies” program. You will find the interview here:

El 0 tv_entrevista Josep Penuelas_13012017

3rd IMBALANCE-P annual meeting – Paris, 1st – 3th February 2017

IMBALANCE_P_Logo_Color_kick off abstractsThe ERC Synergy Imbalance-P project has been running for two years already. A lot of work has been done and some other still needs to be carried out. It is, therefore, time for us to meet again in a confortable city such as Paris.

The format will be similar to last time, researchers will present some of their work/results/projects within the Imbalance-P in short talks of about 15 minutes allowing participants to ask some questions. It is also planned to have time to allow researchers to discuss within the different working groups (experimental, synthesis, modelling…) and among them.

The main aims of the Paris meeting are to:

  1. Present and discuss past, present and future work within the Imbalance-P project.
  2. Share and discuss the results obtained by the different groups.
  3. Develop synergies amongst groups and researchers by increasing collaboration through sharing thoughts, ideas, objectives, experiments, observations and data.
  4. Create a venue where co-authors of different manuscripts can get together to forward their writing and possibilities for such activities to be initiated.

Scientific contact: Philippe Ciais (philippe.ciais@lsce.ipsl.fr)

Administrative Contact: Zoila Lopez (zoila.lopezsiri@cea.fr)

Organisers: Marcos Fernández-Martínez (m.fernandez@creaf.uab.cat) & Josep Peñuelas (josep.penuelas@uab.cat)

The program of the meeting is available here.

https://upload.wikimedia.org/wikipedia/commons/thumb/9/97/Pont_des_Arts%2C_Paris.jpg/1024px-Pont_des_Arts%2C_Paris.jpg

Pont des Arts. Author: Benh LIEU SONG, This picture is licensed under the Creative Commons Attribution-Share Alike 3.0

 

Plausible rice yield losses under future climate warming
Rice fields, researchers analyze the sensitivity of rice yield to climate warming. Photo by Pixabay
Rice fields, researchers analyze the sensitivity of rice yield to climate warming. Photo by Pixabay

Rice is the staple food for more than 50% of the world’s population. Reliable prediction of changes in rice yield is thus central for maintaining global food security. This is an extraordinary challenge.

In a new study in the journal Nature Plants researchers compare the sensitivity of rice yield to temperature increase derived from field warming experiments and three modelling approaches: statistical models, local crop models and global gridded crop models.

Field warming experiments produce a substantial rice yield loss under warming, with an average temperature sensitivity of −5.2 % per degree of warming. Local crop models give a similar sensitivity (−6.3 %), but statistical and global gridded crop models both suggest less negative impacts of warming on yields (−0.8 % and −2.4 7%, respectively).

Using data from field warming experiments, researchers further propose a conditional probability approach to constrain the large range of global gridded crop model results for the future yield changes in response to warming by the end of the century (from −1.3% to −9.3% per degree of warming). The constraint implies a more negative response to warming (−8.3 %) and reduces the spread of the model ensemble by 33%. This yield reduction exceeds that estimated by the International Food Policy Research Institute assessment (−4.2 to −6.4% ).

“Our study suggests that without CO2 fertilization, effective adaptation and genetic improvement, severe rice yield losses are plausible under intensive climate warming scenarios” said Dr. Chuang Zhao, researcher from Peking University.

“The long-term perspective of climate change allows us to prepare agricultural production systems for this challenge, but suitable policies must be put in place in the near future, given that targeted research on adaptation options and their large-scale implementation will require considerable time”, said Prof. Josep Penuelas from CREAF-CSIC Barcelona.

Citation: Zhao, C., Piao, S., Wang, X., Huang, Y., Ciais, P., Elliott, J., Huang, M., Janssens, I.A., Li, T., Lian, X., Liu, Y., Müller, C., Peng, S., Wang, T., Zeng, Z., Penuelas, J. 2016. Plausible rice yield losses under future climate warming. Nature Plants 3, 16202 (2016), doi: 10.1038/nplants.2016.202.

Losses of soil carbon under climate warming might equal U.S. emissions
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Carbon stores are greatest in places like the Arctic and the sub-Arctic, where the soil is cold and often frozen Photo by SHUTTERSTOCK

 

A new global analysis finds that warming temperatures will trigger the release of trillions of kilograms of carbon from the planet’s soils, driven largely by the losses of carbon in the world’s colder places.

 See short video about this paper: https://youtu.be/IrKOpPJIbXA

New Haven, Conn. – For the past two decades, scientists have speculated that rising global temperatures may alter the ability of soils to store huge amounts of carbon. If warming accelerates the release of carbon stored in the soil, it could trigger a dangerous feedback effect that could have runaway effects on climate change. Yet, despite thousands of studies around the world, we have remained unclear about whether soil carbon storage will increase or decrease in response to warming.

Finally, a global perspective has allowed us to see past the mixed results of single-site studies to see the global patterns in this effect.

In a new study in the journal Nature researchers find that warming will drive the loss of trillions of kg of carbon from the soil. A conservative estimate by the researchers suggest that this value will exceed 55 trillion kg by 2050.

This value would represent up to 17% on top of current anthropogenic emissions that we expect over that time.

The results are based on an analysis of soil carbon data from dozens of warming experiments conducted all over the world in the past 20 years.

Using this worldwide dataset, the researchers generated a global map of the sensitivity of soil carbon to warming, showing that carbon loss is greatest in the world’s colder places, at high latitudes, where massive stocks of carbon have built up over thousands of years and slow microbial activity has kept them relatively secure.

“Soil carbon stores are greatest in places like the Arctic and the sub-Arctic, where the soil is cold and often frozen. In those conditions microbes are less active and so carbon has been allowed to build up over many centuries,” said lead author Thomas Crowther, at the Yale School of Forestry & Environmental Studies (F&ES).

“But as you start to warm those areas, the microbes become more active, that’s when the carbon losses are likely to happen,” Crowther said. “The scary thing is, these cold regions are the places that are expected to warm the most under climate change.”

The study predicts that for one degree of warming, about 30 petagrams of soil carbon will be released into the atmosphere, or about 2-3 times as much as is emitted annually due to human-related activities. This is a sobering prospect, given that the planet is likely to warm by 2 degrees Celsius by mid-century.

Other scientists on the team include Marc Estiarte and Josep Peñuelas from CREAF, as well as collaborating researchers from more than 30 other institutions.

Marc Estiarte commented on the value of the results: “We suspected that cold regions were key because warming could potentially reverse the carbon-accumulating pressure that cold temperatures have been exerting since such a long time”

The results represent a warn because “the vulnerability of the northern soil carbon pool is a threat to the stabilization of the CO2 concentrations in the atmosphere due to the positive feedback that can unfold between climate warming and soil carbon losses to the atmosphere”, in the words of Josep Peñuelas.

Understanding these processes at a global scale is critical for our understanding of climate change. “Getting a handle on these kinds of feedbacks is essential if we’re going to make meaningful projections about future climate conditions. Only then can we generate realistic greenhouse gas emission targets that are effective at limiting climate change,” said Crowther.

More information: T. W. Crowther et al, Quantifying global soil carbon losses in response to warming, Nature (2016). DOI: 10.1038/nature20150
A remotely sensed pigment index reveals photosynthetic phenology in evergreen conifers
Boreal forest
Boreal forest, researchers find a close correspondence between seasonally changing foliar pigment level and evergreen photosynthetic activity Photo by ŠtefanŠtefančík

In evergreen conifers, where the foliage amount changes little with season, accurate detection of the underlying “photosynthetic phenology” from satellite remote sensing has been difficult, causing errors in terrestrial photosynthetic carbon uptake models. This represents a challenge for global models of ecosystem carbon uptake.

In a new study in the journal Proceedings of the National Academy of Sciences researchers find a close correspondence between seasonally changing foliar pigment levels, expressed as chlorophyll/carotenoid ratios, and evergreen photosynthetic activity, leading to a “chlorophyll/carotenoid index” (CCI) that tracks evergreen photosynthesis at multiple spatial scales.

When calculated from NASA’s Moderate Resolution Imaging Spectroradiometer satellite sensor, the CCI closely follows the seasonal patterns of daily gross primary productivity of evergreen conifer stands measured by eddy covariance.

This discovery provides a way of monitoring evergreen photosynthetic activity from optical remote sensing, and indicates an important regulatory role for carotenoid pigments in evergreen photosynthesis. “This methodology could improve the assessment of the evergreen component of the terrestrial carbon budget, which has been elusive” said Prof. Josep Peñuelas.

“Improved methods of monitoring photosynthesis from space can improve our understanding of the global carbon budget in a warming world of changing vegetation phenology”, said Prof. John Gamon.

 

Citation: Gamon, J., Huemmrich, J.K.F., Wong, C.Y.F., Ensminger, I., Garrity, S., Hollinger, D.Y., Noormets, A., Peñuelas, J. 2016. A remotely sensed pigment index reveals photosynthetic Q:1 phenology in evergreen conifers. Proceedings of the National Academy of Sciences, 2016. In press

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