A networking resource devoted to biological soil crusts and the researchers who study them. We will provide a means for international scientists to communicate, share their research, share important news and announcements, ask questions and find collaborators. We will also provide a space for informal writing on research, opinion, and ideas (now seeking posters!).

Saturday, August 18, 2012

Ecological Society of America meeting encrusted

On the way to dinner. Pictured are Nichole Barger, Bettina Weber, Yunge Zhao, Yuanming Zhang, Matthew Bowker, Jayne Belnap, Burkhard Budel, James Meadow, Mingxiang Xu, Lea Condon, and two young family members. Elisabeth Huber-Sannwald must be taking the photo. I picked the photo with the fewest closed eyes, but we are looking into the sun. Also I was standing on the highest steps and am not actually 8 feet tall.
The last time there was a crust session at ESA (also in Portland, several years ago), I recall good talks but the funny thing was that everyone (me too!) did the same crust 101 introduction......even lifting the same photo from the web. Another notable thing was that by and large the audience was made up of speakers in the session. This one, organized by Bettina Weber and Jayne Belnap, drew more people (speakers were perhaps 25% of the audience...despite it being the last day), and we basically assumed that if you're attending a session about biological crusts you know what they are and went without much introductory material. Finally, I believe that last time, all speakers were from the US. This time around we had representation from Germany and Mexico, and three of our Chinese colleagues made the long trip. If you take into account all coauthors, we add Australia, Spain, and Colombia. I think all are signs that both awareness of and interest in biocrusts are increasing....we are less and less fringe lunatics. Next year we have the second international crust conference in Madrid to keep up the momentum.

Hugo Beraldi-Campesi spoke about how he believes we should rewrite the story of the colonization of land by living organisms. It is difficult to make inferences about this time because most rocks of the crucial age have been recycled by the Earth's grand conveyor belt. But the idea that plant communities were the first land communities ought to rightfully be viewed with scrutiny, since we know cyanobacteria were around and they had the entire toolbox (desiccation tolerance, n-fixation, UV- protective pigments) to colonize land. James Meadow introduced us to a fascinating community of biocrusts with a labyrinthine physical structure (apparently initially created by goose footprints), growing near hot springs in Yellowstone. I propose the term "Sharpei-oid" for this structure. He presented some of the lessons of molecular characterization of this community which was cool, but I think he had already amazed us when he told us that most of the soil particles are in fact discarded frustules of diatoms. What a weird community. Check out his photos below.

Rebecca Hernandez spoke about a gradient of California study sites sampled for biocrust moss and lichen diversity. She identified over 80 species, which is a pretty high number. She had a look at other studies and proposed that not only are Meditterranean ecosystems hotspots for plant biodiversity, but also for biocrust diversity. I think its an intriguing idea that I'd like to see developed further in a formal metanalysis at a global scale. Perhaps due to my experience with gypsiferous soils (rich in crust species, poor in plant species), I'd often thought there was a negative correlation between biocrust and plant diversity....but maybe not. Burkhard Budel took us on a world tour of his crust study sites including Africa, Australia, and Antarctica. He spoke about the diversity of photosynthetic behavior of crust organisms. For example green algal lichens can photosynthesize when humidity is high, whereas cyanobacterial lichens require liquid water. Different species of lichens exhibit different response surfaces to light, moisture, and temperature gradients; for, example they can have markedly different degrees of photosynthetic depression due to oversaturation. This really struck me as an example of how species diversity can promote productivity. In a plot with many species with complementary photosynthetic patterns, photosynthesis will be active in portions of the crust throughout a wider parameter space of light-moisture-temperature. Nicole Pietrasiak advanced a model of landscape development in the Mojave desert. There are 2 pathways in her model, an abiotic and a biotic one. Along the abiotic paths vegetation becomes sparse a desert pavements from. If, however there is bioturbation from rodent burrowing activity shrub density increases, the pavement never develops and biocrusts are happiest. Yuanming Zhang presented one of the best studies I've seen on the recurrent but never quite answered question: are crusts good or bad for plants? Our problem is that we usually want to study only one facet of this interaction, like germination success, which is not at all the entire picture. The answer isn't simple, it depends on the phenology and identity of the plant and the type of crust. Reduced seedbank and germination effects of biocrusts occurred, but herbs which do germinate on crusts grow faster and their reproductive period is altered. Bruce McCune, on about 12 hours of notice, filled in a vacany in the schedule. He presented some work of his student, Heather Root, modeling the distributions of rare lichens and determining the footprint of human land use on the potential niche of these species. It turns out that Texosporum Sancti-jacobi prefers to grow (perhaps I should say did grow, once) where we prefer to grow crops and install wind farms.Yunge Zhao presented some of her work restoring mosses to eroding landscapes of the Loess Plateau. Using ground moss tissue she is able to field inoculate and reduce erosion rates by about 30% in one year. Bettina Weber estimated the contributions of cryptogamic communities on soil, rock and trees to global C and N fixation. The majority of the planet's N-fixation was attributed to these communities, as well as 7% of the C-fixation which is more than the human C-flux from fossil fuels. Finally I did a review of the utility of biocrusts as a model system for learning about ecology. We've been invited to do a special issue for the journal Ecological Processes, a new open access journal from Springer.

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