Changes in biocrust cover drive carbon cycle responses to climate change in drylands Maestre Global Change Biology Wiley Online Library

Changes in biocrust cover drive carbon cycle responses to climate change in drylands Maestre Global Change Biology Wiley Online Library

A new one from Fernando Maestre, Cristina Escolar et al....nice work!

Global warming may affect soil microbe survival, with unknown consequences on soil fertility and erosion

Global warming may affect soil microbe survival, with unknown consequences on soil fertility and erosion


Ferran Garcia-Pichel & co. are at it again, first ISME just a couple weeks ago and today he has biocrusts on the cover of science.

June 28 2013, Science. Microcoleus vaginatus (blue) on the left, Microcoleus steenstrupii (red) on the right. As climate warms, there will be a changing of the guard in the biocrusts.

Original article is here.

BIOCRUST 2013, Madrid Day 1 Report

Arriving home after an all-nighter. Just joking! Actually, this is just how happy crust enthusiasts are to see others of their kind. We are heading out for dinner near the recently made-over Rio Manzanares. L-R: Chongfeng Bu, Jayne Belnap, Jayne's granddaughter Haylee (I'm guessing on spelling), Sasha Reed, Bettina Weber, Yunge Zhao, Nichole Barger, Sergio Velasco Ayuso, Ana Giraldo, Ferran Garcia-Pichel.

Many thanks to Leopoldo Sancho & Fernando Maestre and their respective labs for putting on a fantastic workshop on biological soil crusts in Madrid (aka BIOCRUST 2013). There were about 80 speakers and about 30 posters presented, and the organizers are working on compiling pdfs of all of these which will eventually be available here. Obviously Spain was well-represented, but we had a great international mix of researchers from France, Portugal, Germany, Poland, The US, The UK, Israel, Australia, Venezuela, New Zealand, Colombia, and others. An impressive development compared to the last workshop was the representation of our Chinese colleagues. Three different Chinese research groups were represented. Everyone I talked to enjoyed the short talks (10 minute slots). Also I liked that the posters were hung for the duration, so that every coffee break became a poster session. On the final day we had three proposals for the 2016 conference: 1. University of Queensland, Australia with an overnight field visit to Magnetic Island (Wendy Williams) , 2. Moab, Utah, USA (Jayne Belnap), 3. The Negev Desert, Israel (Eli Zaady). I think all of these ideas were winners, but Moab took the votes. 

Dinner, the night before the conference. 

A few day one highlights - 
Sasha Reed talked about effects of warming and increased precipitation frequency primarily on mosses.  The mosses nearly completely die-off due to high frequency, short duration hydration events. The use of infrared heating lamps sparked some discussion because they deliver not only a warming treatment but also a drying effect. In my opinion, real global warming will also come with drying...therefore the lamps are a reasonable simulation. Cristina Escolar followed this up perfectly with her results using passive warming chambers. The warming (and probably associated drying) is killing off lichens, and reducing production but increasing soil carbon. The authors think the carbon is from the decomposition of the lichens, and that in the long term sequestration potential will decrease.

There was considerable excitement when Nick Vandehey spoke about the Berkeley lab's capability of making C11, a short-lived radio-isotope, incubating crusts with labeled CO2, then producing an image displaying not only how much C was fixed, but also the spatial pattern of C-fixation.

Enrique Valencia spoke about his recently started project which manipulates crust biodiversity and two global change factors. It's like the Cedar Creek experiment in miniature - both in size and budget, a perfect model system.

Possibly the talk that sparked my personal interest the most on day one was Antonio Gallardo's. He looked at the effects of different lichen species on soil C and N species, soil microbiota (including ammonia oxidizers), and polyphenol chemicals. First he found that all lichens regardless of the species were more similar to each other in terms of their effects on the above mentioned variables than to either bare areas, or soil under grasses. When honing in just on the lichens they did have distinct influences on the soil biogeochemical cycling. It was Diploschistes diacapsis that exerted the most unique effects on most variable, and also this lichen that contained the most polyphenols. This suggests that the lichens influence soil microbial communities with their polyphenols, and therefore alter the biogeochemical cycling performed by the soil microbes.

Having some tapas in the city center before going to dinner.  (L-R: Anita Antoninka, Nichole Barger, Antonio Gallardo, Ferran Garcia-Pichel, Sasha Reed, Santi Soliveres, Manu Delgado, Sergio Velasco).

A little explanation: So, a man came in and wouldn't leave us alone until Ferran bought some flashing bows that you wear on your head. They came out for the photos.

Another footnote: apparently this restaurant was on Gordon Ramsey's reality TV show Kitchen Disasters. 

Conference attendees recreate Da Vinci's last supper.

This is made even more perfect by Sasha's glowing and blinking "halo", purchased for only 1 euro. Give her a break, she gave her talk that morning and its the night before her birthday. (L to R): Santi Soliveres, Antonio Gallardo, Ferran Garcia-Pichel, Sergio Velasco, Sasha Reed, Anita Antoninka, Bettina Weber, Manu Delgado.

The Zombie Mosses Rise from Beneath a Glacier

This is a pretty nice blog post from bryology post-doc Jessica Budke on the amazing regrowth of centuries-old mosses from under a retreating glacier that was in the news recently. She includes some nice links to press and radio interviews.





The Zombie Mosses Rise from Beneath a Glacier

Bryophytes Frozen Under a Glacier for 400 Years Can Come Back to Life | Surprising Science

This one's making the science news rounds...


Plants Frozen Under a Glacier for 400 Years Can Come Back to Life | Surprising Science

La Farge C, Williams KH, England JH. 2013. Regeneration of little Ice Age bryophytes emerging from a polar glacier with implications of totipotency in extreme environments, PNAS dpi:10.1073/pnas1304199110.

Paper by Coe et al. recommended by Faculty of 1000

Faculty of 1000 is a panel of faculty members which recommends and ranks the best papers they have read in their fields, post-publication. It is sort of a post-publication peer review, and in addition to citation rates give an indication of the impact or quality a paper may have.

Scott Collins of University of New Mexico, a heavy hitter in dryland ecology specifically, and also the president of ESA has recommended Coe, K.K., Belnap, J., Sparks, J.P. 2012. Precipitation-driven carbon balance controls survivorship of desert biocrust mosses. Ecology 93: 1626-36. This is really a great honor for the authors, and I am really psyched to see my very first study subject, Syntrichia caninervis, making it big.

Check out my previous post about related work by some of the same authors here. Also CO2 Science summarizes another related work here.

Plate 1.  (Left) A moss-dominated soil biocrust from the Colorado Plateau in western North America, and (right) a single shoot (height 1 cm) of the widespread biocrust moss Syntrichia caninervis. Photo credits: left, K. K. Coe; right, Lloyd Stark.

View the recommendation here:

Collins S: F1000 Prime Recommendation of [Coe KK et al., Ecology 2012, 93(7):1626-36]. Faculty of 1000, 18 Oct 2012; DOI: 10.3410/f.717955503.793460788. f1000.com/prime/717955503#eval793460788

Dryland Biological Soil Crust Cyanobacteria Show Unexpected Decreases in Abundance Under LongTerm Elevated CO2 Steven Environmental Microbiology Wiley Online Library

Dryland Biological Soil Crust Cyanobacteria Show Unexpected Decreases in Abundance Under LongTerm Elevated CO2 Steven Environmental Microbiology Wiley Online Library

Theme Issue 'Impacts of global environmental change on drylands: from ecosystem structure and functioning to poverty alleviation'

Out today, a special issue of Philosophical Transactions "Impacts of global environmental chang on drylands: from ecosystem structure and functioning to poverty alleviation" edited by Fernando Maestre and Roberto Salguero-Gómez.

Below are the 2 most biocrust focused abstracts, but I recommend the whole issue as it contains submission by the editors, Andrew Dougill, and Elisabeth Huber-Sannwald. Happy reading.

• Andrew D. Thomas

Research article: Impact of grazing intensity on seasonal variations in soil organic carbon and soil CO₂ efflux in two semiarid grasslands in southern Botswana Phil. Trans. R. Soc. B November 19, 2012 367 1606 3076-3086; doi:10.1098/rstb.2012.0102 1471-2970 

 Biological soil crusts (BSCs) are an important source of organic carbon, and affect a range of ecosystem functions in arid and semiarid environments. Yet the impact of grazing disturbance on crust properties and soil CO₂ efflux remain poorly studied, particularly in African ecosystems. The effects of burial under wind-blown sand, disaggregation and removal of BSCs on seasonal variations in soil CO₂ efflux, soil organic carbon, chlorophyll a and scytonemin were investigated at two sites in the Kalahari of southern Botswana. Field experiments were employed to isolate CO₂ efflux originating from BSCs in order to estimate the C exchange within the crust. Organic carbon was not evenly distributed through the soil profile but concentrated in the BSC. Soil CO₂ efflux was higher in Kalahari Sand than in calcrete soils, but rates varied significantly with seasonal changes in moisture and temperature. BSCs at both sites were a small net sink of C to the soil. Soil CO₂ efflux was significantly higher in sand soils where the BSC was removed, and on calcrete where the BSC was buried under sand. The BSC removal and burial under sand also significantly reduced chlorophyll a, organic carbon and scytonemin. Disaggregation of the soil crust, however, led to increases in chlorophyll a and organic carbon. The data confirm the importance of BSCs for C cycling in drylands and indicate intensive grazing, which destroys BSCs through trampling and burial, will adversely affect C sequestration and storage. Managed grazing, where soil surfaces are only lightly disturbed, would help maintain a positive carbon balance in African drylands. 

• Cristina Escolar,
• Isabel Martínez,
• Matthew A. Bowker,
• and Fernando T. Maestre

Research article: Warming reduces the growth and diversity of biological soil crusts in a semi-arid environment: implications for ecosystem structure and functioning Phil. Trans. R. Soc. B November 19, 2012 367 1606 3087-3099; doi:10.1098/rstb.2011.0344 1471-2970 

Biological soil crusts (BSCs) are key biotic components of dryland ecosystems worldwide that control many functional processes, including carbon and nitrogen cycling, soil stabilization and infiltration. Regardless of their ecological importance and prevalence in drylands, very few studies have explicitly evaluated how climate change will affect the structure and composition of BSCs, and the functioning of their constituents. Using a manipulative experiment conducted over 3 years in a semi-arid site from central Spain, we evaluated how the composition, structure and performance of lichen-dominated BSCs respond to a 2.4°C increase in temperature, and to an approximately 30 per cent reduction of total annual rainfall. In areas with well-developed BSCs, warming promoted a significant decrease in the richness and diversity of the whole BSC community. This was accompanied by important compositional changes, as the cover of lichens suffered a substantial decrease with warming (from 70 to 40% on average), while that of mosses increased slightly (from 0.3 to 7% on average). The physiological performance of the BSC community, evaluated using chlorophyll fluorescence, increased with warming during the first year of the experiment, but did not respond to rainfall reduction. Our results indicate that ongoing climate change will strongly affect the diversity and composition of BSC communities, as well as their recovery after disturbances. The expected changes in richness and composition under warming could reduce or even reverse the positive effects of BSCs on important soil processes. Thus, these changes are likely to promote an overall reduction in ecosystem processes that sustain and control nutrient cycling, soil stabilization and water dynamics. 

Why mosses can grow in the desert, and why their future is uncertain

Readers of this blog won't be so surprised, but most people are unaware that mosses grow in deserts and semiarid zones. The reason they can do so is that desert mosses are dessication tolerators, meaning they are capable of drying without dying. While dry, they are in a state of suspended animation, simply waiting for the next hydration period so that biological activity - and hopefully - net photosynthesis can occur. They rehydrate literally in seconds, and are immediately active. You could measure their respiration right away, for example. I always tell people that this is somewhat like spilling a glass of water on Tutankhamun, resulting in him coming back to life. A pretty cool party trick in my opinion. Biocrust organisms in general do this, but it is perhaps most dramatic in the mosses. Here's a video posted by Casey Allen of a simulated rain event.

And another from a class led by Larry Macafee at Badlands National Park. Focus is a little fuzzy, but you can see individual plants hydrating.

Neat trick for sure, but it does come with costs. Biocrust organisms do not regulate water loss with stomates (pores which a plant can open and close to regulate the rate of carbon coming in and water going out), so they lose that water they gained passively due to simply evaporation. They hang onto water very similarly to a piece of a paper towel - soaking it up via contact and losing it to evaporation. Every dry down event is thought to damage membrane integrity a little bit, so that the first order of business when rehydrating is maintenance. Many researchers have shown that upon rehydration there is a period of net respiration, and that after the photosynthetic rate may exceed the respiration rate, resulting in positive carbon uptake. If that happens growth is possible. But if that net photosynthetic threshold is not reached, the hydration event has resulted in carbon loss, and therefore dry mass loss. In other words the mosses would be shrinking a tiny bit rather than growing....bad news. So you can imagine that short hydration events due to small rain events or just high temperature driving fast evaporation, could damage mosses. Further, many such events could even kill them. So nature's tough guys have an Achilles heel, and seem to straddle a knife edge of survival. The climate is changing: what if increased temperatures or altered frequency or magnitude of rain events decrease hydration times? These mosses seem vulnerable to catastrophe.

Recent papers, including an awesome one by Reed et al. in Nature Climate Change, have induced rapid changes in biocrust community composition as a function of experimental climate change manipulations in a 5 year experiment. They induced a 2 degree C warming using infrared lamps in the field in Utah. This is a modest warming effect compared to multi-GCM projections for the area. They crossed this warming effect with a watering treatment which doubled the frequency of rain events but only slightly increased the total amount of rainfall. It's not surprising to me that this had an effect....but what is surprising is that the authors induced a 90% moss mortality in only 1 year!.

Moss dieback in response to increased frequency of small summer rainfall events (Zelikova et al. 2012)

Mosses fail to attain net photosynthesis when experiencing 1.25 mm rain events, contrasting with a 5 mm rain event (Reed et al. 2012).

This effect was essentially exclusively driven by the watering frequency treatment. The group also tracked effects rippling through the entire community. Under the high frequency summer rain treatment, cyanobacterial cover apparently expanded filling the gap left by the mosses, but pigment concentrations suggest that biomass was declining (Zelikova et al. 2012). Meanwhile bacteria and fungi were in decline (Zelikova et al. 2012), and enzyme signatures suggested that decomposition rates were faster under the frequent watering regime. In addition, changes were induced to nitrogen cycling, including increased nitrfication and a shift from an ammonium to a possibly leakier nitrate dominated regime.

Unlike temperature projections, precipitation projections from climate models are notoriously variable. Therefore, we don't know if climate changes will induce this utter tanking of biocrusts and their function. It is a plausible scenario, however,  that the summer monsoon in the Colorado Plateau region would bring a higher frequency of storms. This is exactly what we don't want. Not only would we lose soil fertility, but biocrusts would be less able to aggregate soils and prevent dust emissions which could go on to affect Western US water supplies (see previous post).

I should point out that this simulated climate change scenario is not necessarily the most plausible in all drylands, and the apparent indifference of biocrusts to warming may also not be universal. These studies from Utah, contrast nicely with another study which shows a clear negative effect of 2 - 4 degree C warming on lichen-dominated biocrusts in Spain (Escolar et al. in press).

Escolar C, Maestre FT, Martínez, I, Bowke, MA 2012. Warming reduces the growth and diversity of lichen dominated biological soil crusts in a semi-arid environment: implications for ecosystem structure and function. Proceedings of the Royal Society B: in press.

Zelikova TJ, Houseman DC, Grote EE, Neher DA, Belnap J. 2012. Warming and increased precipitation frequency on the Colorado Plateau: implications for biological soil crusts and soil processes. Plant & Soil DOI 10.1007/s11104-011-1097-z

Reed SC, Coe KK, Sparks JP, Houseman DC, Zelikova, TJ, Belnap J (2012). Changes to dryland rainfall result in rapid moss mortality and altered soil fertility. Nature Climate Change DOI: 10.1038/nclimate1596

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