Sunday, December 18, 2011
European Geoscience Union General Assembly, Vienna, Austria 22-27.
Biological soil crusts and ecogeomorphological processes
Conveners : Giora J Kidron, Burkhard Büdel, Jayne Belnap, Xin-Rong Li
Situated at the atmosphere-soil boundary, biological soil crust (BSC) plays an important role in the ecology and microbiology of ecosystems. It plays an important role in C and N cycling and plant germination. But it also plays a seminal role in geomorphological processes such as eolian, hydrological, and pedological processes. BSC may effectively impede wind erosion or water flow. Yet, due to hydrophobic properties or extra cellular polysaccharides that act to clog the surface, the crust may also trigger runoff, which may result in nutrient and sediment translocation. The crust may also affect pedological processes either as a result of its organic matter content or due to microorganism-mineral interactions. Focusing on abiotic-biotic relations, this session will examine the abiotic variables responsible for crust establishment and will explore the crust properties and the crust effect on ecogeomorphological and pedological processes responsible for shaping our environment.
Dynamics of soil surface characteristics (including physical and biological soil crusts): consequences on soil functionning and role of climate and land use change
Conveners : O. Cerdan
Co-Conveners : O. Malam Issa, B. Marin, J.L. Rajot
At the interface between the atmosphere and the pedosphere, soil surface characteristics (SSC) have a strong impact on soil functioning. Soil surface characteristics are subjected to changes driven by several interactions between water, air and biotic and abiotic components under the controls of climate and human activity. Illustrative examples of such interactions are provided through crusts formation pattern in arid environments like Sahel where land overuses and drought lead to soil denudation, changes in vegetation pattern and development of physical and biological soil crusts in the plant interspaces. The characteristics and formation of these crusts influence the hydrological balance, control the mass of eroded sediment and influence plant productivity through the modification of nitrogen and carbon cycle. This session provides an opportunity to address recent developments in the comprehension of the environmental importance of soil surface characteristics. The session will focus on changes of soil surface structure due to climate and soil uses and its impact. We are expecting to gather observations from different climatic areas investigating the impact of soil surface characteristics dynamics at small and large temporal and spatial scales. The following questions will be addressed: How climate change and land uses change will affect soil surface characteristics and how this in turn will affect soil properties and functioning? How the structure and composition of communities living at soil surface affects ecosystem processes, functioning and stability of the environment? Contributions dealing with detection and mapping of the spatial distribution of soil surface characteristics are also particularly welcome.
Sunday, November 20, 2011
Biocrusts as a model system: A new method to determine the influence of individual species on ecosystem function
Even if you do not habitually read Nick Gotelli's work, chances are good that if you are an ecologist you have used his software, have one of his books on your shelf (or at least studied it in Ecology class), or have had him as an editor. I don't know all that much about him personally, but when I met him I learned he is also a bluegrass musician and has a fondness for Hieronymus Bosch. This indicates a creative personality which may explain why he has been such a force in methods development and refinement in ecology, particularly involving null models.
Briefly this is how a null model works: 1. You determine a pattern that you expect to arise in your data if a certain process is occurring; classic example is if there is competition among species then you expect spatial segregation among different species, 2. You develop a metric which tells you how strong this patterning is in a given sample, 3. You calculate the metric for a given sample, 4. You compare the calculated metric to those for a large sample of simulated data (usually based on resampling of your real data) which are patterned only by random chance; the algorithm that generates these random samples is your null model, 5. If your real value is more patterned than a large proportion (let's say 95%...but not necessarily) of the simulated samples, you would infer that the process is actively patterning your samples. Not so conceptually challenging, right?
The idea came from Diamond's checkerboard concept (Diamond 1975) that certain species combinations do not occur due to competition (based on bird distribution across New Guinean islands). Connor and Simberloff (1979) created the null model to test whether the number of checkerboard pairs differed from chance alone...it didn't in their test. So in this case, the checkerboard (a pair of species never in the same sample) was the pattern being detected, the metric was the number of checkerboards, and it was compared to randomly structured data. This set off a storm of controversy and one of ecology's greatest debates. But regardless of where you stand on that particular debate, there is considerable utility in the null model approach and they can be applied to a wide variety of questions.
It's really cool that out of all the possible biota, Drs. Gotelli and Maestre have developed a new method using biocrusts as a model system. They applied it to field data, and Andrea Castillo's constructed experimental crusts. Every chance I get, I like to tell people what a great model biocrusts are in community ecology (and maybe landscape ecology too) for empirical tests of theory, e.g. biodiversity effects on function, the stress gradient hypothesis, intransitive competition as a diversity conserving mechanism to name a few. Fernando has really been a pioneer in this arena. I'm glad to see Dr. Gotelli also sees the utility in this study system.
Briefly, this method compares the difference in a given functional response (e.g. photosynthetic rate, enzyme activities, etc.) in samples that contain a particular species and samples which do not. It can be applied to non-experimental field data, taking advantage of natural variation (i.e. a natural experiment). For each species, it calculates a difference (D) between the mean value of some function in samples with the species present and the mean value of the function in samples with the species absent. Then to create the random expectation, the values of function are scrambled randomly among samples, and D is calculated. This process is repeated a large number of times usually until you have thousands of these randomly structured D values. Thus you have an entire distribution of null D-values with which to compare to the real D-value calculated from your data. A standardized effect size can be calculated by subtracting the mean random D from the real D-value, and dividing by the standard deviation of the randomized D-values.
This paper is especially interesting to me, since I have also worked on some of the data that were used to develop the method in this paper (Bowker et al. 2011). I also have tried to tease out the impact of individual species on ecosystem functions. I had the sense that there was a low level of redundancy among the macroscopic crust components, the mosses and lichens. My reasoning was that if different species exhibit unique functional profiles (a suite of effects on different ecosystem functions) then they were not redundant. My approach to this problem was to seek correlations between certain species and higher functional values in ordination space. The biggest flaw with my approach is that it is difficult to get much information on the rarest or less abundant species. I'm not sure if Gotelli's method gets around this issue. It seems it would be difficult to get a good estimate of D if you have relatively few presences of a particular species. I think it's important to note that in both papers (Bowker et al. 2011, Gotelli et al. 2011), the importance of a species must be understood in a community context. For example if Squamarina lentigera has a strong positive relationship with phosphatase activity, it does not mean that Squamarina is making large amounts of phosphatases. It may be, but it may also be altering the abundance of other organisms which do influence phosphatase. In other words the effects can be indirect. Also, the authors are careful to note that null models can be deceptive. For example, an apparent effect of the species on a function may be observed if: a. the function being considered is actually influencing the abundance of the species, not vice-versa, or b. both arise due to a third mechanism such as spatial variation in soil properties. But if you take steps in your sampling design to minimize these possibilities, you are on firmer ground. For these inferential weaknesses, null models will not supplant experimentation, but they complement it well. An experiment adding or removing all community members to determine their effect on ecosystem function can get overwhelming and impractical fast. A null model analysis can help identify a smaller set of species which can be examined in an experimental context. Furthermore, you may already have a dataset amenable to this null model analysis (I do), whereas designing and running an experiment de novo may take years. In any case, I'm looking forward to applying this new technique and the FORTRAN program supplied with the paper.
Bowker MA, Mau RL, Maestre FT, Escolar C, Castillo AP. 2011. Functional profiles reveal unique ecological roles of various biological soil crust organisms. Functional Ecology 25: 787-795.
Connor EF, Simberloff D. 1979. The assembly of species communities: chance or competition? Ecology 60: 1132-1140.
Diamond JM. 1975. Assembly of species communities. Pages 342-444 in Cody ML, Diamond JM, eds. Ecology and evolution of communities. Harvard University Press, Cambridge, Massachusetts, USA.
Gotelli, N., Ulrich, W., & Maestre, F. (2011). Randomization tests for quantifying species importance to ecosystem function Methods in Ecology and Evolution DOI: 10.1111/j.2041-210X.2011.00121.x
Friday, November 11, 2011
I found this interesting tidbit on the Greater Yellowstone Science Learning Center website: Novel Diatomaceous Biological Soil Crust Assemblage in Yellowstone National Park Thermal Soils.Not much info about his ongoing project but there are some photos of the habitat.
Wednesday, November 9, 2011
Saturday, November 5, 2011
Wednesday, November 2, 2011
I was so busy with it that I took exactly zero photos. I will try to rectify this situation by collecting other people's photos and posting them in the next few weeks.
One of my new friends from the conference and hopefully future collaborators is Trent Northen. Turns out Trent just started his own crust-dedicated webpage here. Check out his photos from the symposium and field trips in Arizona. I've asked him to also post on Geodermatophilia.
Saturday, October 22, 2011
1. Teusday October 25
11th Biennial Conference of Research on the Colorado Plateau,
High Country Conference Center,
Northern Arizona University,
(There's a whole conference, but this is what you came to see)
Biological Soil Crusts: Understanding, modeling, and restoring their function in ecosystems, Part I
Moderator: Matthew Bowker, U.S. Geological Survey
9:40-10:00 AM MATTHEW BOWKER – Understanding, modeling, and restoring biocrust function in ecosystems: introduction to special session
10:00-10:20 AM JAYNE BELNAP, M. Bowker – Interactions between biocrust microtopography and ecosystem function
10:20-10:40 AM GREGORY CAPORASO, B. Prithiviraj, S. Bates, R. Knight – Recovery of biological soil crust-like microbial communities in previously submerged soils of Glen Canyon
10:40-11:00 AM NICHOLE BARGER, H. Guenther, M. Miller, J. Herrick – Fire mitigation practices in piñon-juniper woodlands: Soil erosion increases related to declines in biological soil crust communities
11:00-11:20 AM STEVEN WARREN, L. St. Clair, J. Johansen – Effects of prescribed fire on biological soil crust and their subsequent recovery in a juniper woodland
11:20-11:40 AM TRENT NORTHEN, N. Klitgord, U. Nunes da Rocha, S. Axen, L. Rajeev, E. Luning, N. Bouskill, B. Bowen, C. Kerfeld, J. Fortney, R. Salve, E. Brodie, A. Mukhopadhyay, F. Garcia-Pichel – Resolving community and metabolic dynamics and carbon flux in Colorado Plateau biological soil crusts
11:40-12:00 PM Open Questions
Biological Soil Crusts: Understanding, modeling, and restoring their function in ecosystems, Part II
Moderator: Matthew Bowker, U.S. Geological Survey
1:30-1:50 PM MATTHEW BOWKER, T. Arundel – Maps of the biological soil crust potential of the Colorado Plateau: A resource prepared for the Bureau of Land Management ecoregional assessment
1:50-2:10 PM COLBY BRUNGARD, J. Boettinger – Spatial prediction of biological soil crust classes in and around Canyonlands National Park: Implications for biological soil crust management on the Colorado Plateau
2:10-2:30 PM NICOLE DECRAPPEO – Using biological soil crusts to assess the suitability of degraded rangeland sites for restoration
2:30-2:50 PM LINDSAY CHIQUIONE, M. Bowker, L. Stark, S. Abella – Biological soil crust rehabilitation on disturbed gypsiferous soils
2:50-3:10 PM TAMARA ZELIKOVA, D. Housman, E. Grote, D. Neher, J. Belnap – Biocrust response to three years of experimental warming
3:10-3:30 PM FERRAN GARCIA-PICHEL, R. Potrafka, V. Loza, P. Mateo, S. Bates, T. Soule – Microbial biodiversity and function in biological soil crusts: Among the good, the bad and the ugly, some like it hot
3:30-3:50 PM Panel Discussion
3:50-4:10 PM Open Questions
4:10-4:30 PM Break
7:00 - 9:00 PM
CHONGFENG BU, N. Myers, F. Garcia-Pichel - The artificial cultivation of cyanobacteria-dominated biological soil crusts in the Sonoran Desert.
2. I'm working on adding all of the lead authors to the biocrust researcher directory on the right. Hopefully complete soon.
3. In other news, Bettina Weber and Jayne Belnap put in a biocrust symposium proposal for next year's Ecological Society of America Meeting. Let's hope it comes together, should be fun...in Portland I believe, one of my favorite cities.
Isn't this figure amazing! Check out the blog post by Munson et al. here. It's true, we are hearing alot more about dust storms recently. When I was growing up, I really only remember a few and they never lasted multiple days. The most memorable was when my mom was driving me to school during a dust storm, and one of those refrigerator boxes reinforced with wood was actually airborne and cracked our windshield. That was in the super-wet 1980's. Now its seems multiple dust storms occur ever year in western cities. Just ask anyone in Phoenix:
Arizona Republic headlines 2011:
Dust storm hits Phoenix, limits visibility – July 6
Arizona dust storm leaves big mess, health fears in its wake – July 7
3 Phoenix-area dust storms towered nearly 4000 feet high – July 19
Arizona dust storm: double dose of dust for Valley residents – July 23
Phoenix storms: rain, dust slam Pinal County – Aug 19
Crash amid dust storm at Picacho Peak – 25 Sept.
This is not comprehensive, just a sample. I actually heard about the first of these in the Australian news, then followed them in local papers. The funnest local article I found was a letter complaining to the newspaper for using the arabic word "haboob" rather than the phrase "Arizona dust storm". The guy didn't want us to give credit for our good ole Arizonan dust to the Arabs. You could also ask someone in Lubbock about dust storms. I read that their recent one was 8000 feet tall (~2700 meters!).
Heres the dust story in a nutshell: the reason there are more dust storm is that we are seeing more drought years. Drought shrinks the height and increases the spacing of plants, reducing their ability to buffer erosive forces. The soil crust is the major force reducing erodibility. If crusts are compromised at the same time the plants are drought stricken...and it usually is...the dust will blow (alot).
Sunday, September 25, 2011
The old guy is at it again, making a "sand cake" for his easy-bake oven. To get him out of the loony bin for the day, I had to tell them we were going to see Cars II.
OK, that's not true, actually, Dave is prepping a sand bed for a disc permeameter measurement. He is single-handedly capable of manning about 5 sets of permeameters simultaneously. He has not seen Cars, but he likes that show with the stoner guy dressed up as a dog. In the last few months he has developed a nice new website here.
|Paying my respects at the sheep temple.|
Like North Americans, Australians seem to be found of big pointless things on the side of the road. Whereas we tend towards dinosaurs, Native American paraphernalia such as giant arrows or teepees, or Paul Bunyan and Babe, Australians mostly go for various agricultural products or the occasional tennis racket. This is the giant merino.
Diagram of the formation and subsequent breakup of the supercontinent, Pangaea.
Just kidding, these are crusts...aren't they cool? In Australia most of the lichens were familiar players from North American or Europe, but the mosses are a different universe. I wonder why. So many studies out there compare "crusted" samples versus "non-crusted" samples. This oversimplification has always bothered me a little bit, because it's never so simple. We could call a non-crusted, but b-f are all crusted yet all completely different in terms of composition, total cover, or spatial patterning and heterogeneity.Our interest is in sampling the entire variety that exists.
Wednesday, June 8, 2011
Sohrabi, M., Stenroos, S, Högnabba, F, Nordin, A., Owe-Larsson. 2011. Aspicilia rogeri sp. nov. (Megasporaceae) and other allied vagrant species in North America. Bryologist 114:178-189.
This one is a taxonomic paper passed on to me by Roger Rosentreter. Basically what the authors find is that what we thought was Aspicilia fruticulosa in North America, is actually a new taxon. The best thing about it is that it is named after Roger, Aspicilia rogeri. I like the familiarity of using his first name...now we have our friend Roger the human, and our new friend Roger the lichen. After all his work over the years on this fascinating and frustrating genus...he deserves it. The authors have some additional photos here.
Read, C.F., Duncan,D.H., Vesk, P.A., Elith, J. 2011. Surprisingly fast recovery of biological soil crusts following livestock removal in southern Australia. Journal of Vegetation Science Doi: 10.1111/j.1654-1103.2011.01296.x
Cassia Read follows up one of the first landscape ecology studies of biocrusts with this one about passive recovery of crust after exclusion of livestock. It uses an unusually good gradient of time since disturbance. Also notable is that the more we collectively study this topic the more we find that recovery rates differ from place to place, as well as successional sequences.
Castillo-Monroy, A.P., Maestre, F.T., Rey, A., Soliveres, S., Garcia-Palacios, P. 2011. Biological soil crust microsites are the main contributor to soil respiration in a semiarid ecosystem.
The journal Ecosystems is turning out to be fertile ground for crust research. On a gyspiferous area with well developed crusts, the authors calculate that the biocrust is associated with about 40% of the soil respiration from the site.
Of course one reason I created this blog was to help disseminate my own research. I switched jobs in the last year so I've been sending out less stuff in the transition, but my collaborators have kept me looking good. Here's a few from 2011 and the latter part of 2010:
García-Palacios, P., Bowker, M.A., Maestre, F.T., Soliveres, S., Valladares, F, Papadopoulos, J., Escudero, A. 2011. Ecosystem development in roadside grasslands: biotic control, plant–soil interactions and dispersal limitations. Ecological Applications in press.
Pablo worked really hard for this one. Developing the structural equation model in this paper was like fighting the hydra...we'd solve one problem and create 2 more. But in the end it looks good, congratulations Pablo.
Miller, M.E., Belote, R.T., Bowker, M.A., Garman, S.L. 2011. Alternative states of a semiarid grassland ecosystem: Implications for erosion susceptibility, ecosystem services and management. Ecosphere 2 A55.
Back to the Colorado Plateau....this is part of my new job. One of my projects is related to state-and-transition models. In this paper we actually define an ecosystem state partially by the dominance by biological crusts.
Maestre, F.T., Bowker, M.A., Cantón, Y., Castillo-Monroy, A.P., Cortina, J., Escolar, C., Escudero, A., Lázaro, R. Martínez, I. 2011. Ecology and functional roles of biological soil crusts in semi-arid ecosystems of Spain. Journal of Arid Environments in press.
This is a review of all the varied crust research being conducted in Spain. It will appear in a special issue of Journal of Arid Environments devoted to Spain's semi-arid zone.
Bowker, M.A., Mau, R.L., Maestre, F.T., Escolar, C., Castillo, A.P. 2011. Functional profiles reveal unique ecological roles of various biological soil crust organisms. Functional Ecology doi: 10.1111/j.1365-2435.2011.01835.x.
In this paper we explore the simple idea of tabulating biocrust species and the ecosystem functions that the species tends to correlate with. We focused on the Spanish species. If you do this, you find little redundancy, most of the common species have a unique suite of functional effects.
Castillo-Monroy, A.P., Bowker, M.A., Maestre, F.T., Rodríguez-Echeverría, S., Martinez, I., Barraza-Zepeda, C.E., Escolar, C. 2011. Relationships between biological soil crust, bacterial diversity and abundance and ecosystem functioning: Insights from a semi-arid Mediterranean environment. Journal of Vegetation Science 1:165-174.
Here we added some data on the microbial community to an existing study, and posed the question "How much of apparent crust function is actually mediated by their effects on soil microbiota?" At least in this site, the answer seems to be not much. This was part of Andrea's dissertation.
Eldridge, D.J., Bowker, M.A., Maestre, F.T., Alonso, P., Mau, R.L., Papadopoulos, J., and Escudero, A. 2010. Interactive effects of three ecosystem engineers on infiltration in a semi-arid mediterranean grassland. Ecosystems 13: 499-510.
I'm really happy with this study, and it's mostly thanks to Dave Eldridge. I hope to repay him with an equally good study this month in Australia. We studied the effects of crusts, rabbits and tussock grasses on infiltration in a regression-type design. The tussock grasses are infiltration sites (that was well known already). The rabbits have no direct effect, but they can nullify the crust effect. The crust effect can be positive, if mosses dominate, or negative if lichens dominate. All in all, a very cool system studied as an intact system, rather than breaking it into it's parts.
Friday, June 3, 2011
Anyways, I'm hoping for some good talks, good Thai food, and good beer. Think of it as IBiSCA 2.0, though maybe a better name might be in order.
Saturday, May 28, 2011
"And the wind blows, the dust clouds darken the desert blue, pale sand and red dust drift across the asphalt trails and tumbleweeds fill the arroyos. Good-bye, come again."
The obvious impact of dust emissions in rangelands is that fertility is leaving the site (Neff et al. 2005). The less obvious impacts occur sometimes halfway around the world. Some cities regularly experience crippling dust storms which impact human respiratory health and create blinding conditions on roadways. Beijing is an excellent example, where desertification-linked dust storms have gone from a decadal phenomenon to an annual one, even closing airports for days. In the southwest USA, an endemic fungus responsible for valley fever (a disease causing pheumonia-like symptoms) is transported in dust. Some of the more amazing impacts of dusts may be positive on a global scale, in terms of our prospects for sinking carbon. The two great photosynthetic engines of the Earth, the Amazon rainforest and the oceanic phytoplankton, are both subsidized by dust-borne nutrients from drylands (Fung et al. 2000, Koren et al. 2006, Mahowold 2010).
Painter, T.S., Deems, J.S., Belnap, J., Hamlet, A.F., Landry, C.C., Udall, B. 2010. Response of Colorado River runoff to dust radiative forcing in snow. Proceedings of the National Academy of Sciences 108: 3854 - 3959.
Back in 2006, I was shocked to hear Jayne Belnap on National Public Radio. NPR was doing a two-part series on dust research focused around the work on Tom Painter. The radio journalist even dropped the word "crusties" a time or two.
Four years later, they published this paper which documents the impacts of dust originating form the Colorado Plateau and southwest US drylands and accumulating on Rocky Mountain snowpack. Because the dust is much darker than the soil, it increases albedo and hastens melting. The authors estimate that this has resulted in initiation of melting 3 weeks earlier than ambient conditions. More importantly, the radiative forcing enhances sublimation -- the transition of solid snow to vapor -- which the authors estimate has decreased water supply to the Colorado River Basin by 5 %. This is of tremendous importance as most of the fastest growing urban areas in the USA are in the southwest and at least partially dependent on Colorado River water. As an example, Las Vegas, the city I was born in increased from about 200,000 residents to about 2,000,000 in 3 decades. All of this growth has been founded on the fantasy that there will be enough water, despite that the Colorado River has been 100% allocated for many years. Increasing dust emissions seem to argue otherwise.
Munson, S.M., Belnap, J., Okin, G.S. 2011. Responses of wind erosion to climate-induced vegetation changes on the Colorado Plateau. Proceedings of the National Academy of Sciences doi: 10.1073/pnas.1014947108.
The authors use a trifecta of long-term monitoring data, a wind erosion model, and an experimental validation of results using a portable wind tunnel. Primarily in perrennial grasslands the previous year temperatures dictate grass biomass in the following years. Plugging these data into Okin's wind erosion (WEMO) model suggests greater risk for enhanced dust fluxes due to probable climate warming. The fluxes are small, however, unless the biocrust is disturbed. When heavy crust disturbance is coupled with drought-stricken grasses, the fluxes have the potential to be off the hook.
This paper is getting considerable press, e.g. the Salt Lake Tribune. For those in other countries just check out the comments on that paper to see how effective the smear campaign on climate science has been in the USA. We have an uphill battle.
Post title: Edward Abbey, The Monkeywrench Gang
Belnap, J., R. L. Reynolds, M. C. Reheis, S. L. Phillips, F. E. Urban, and H. L. Goldstein. 2009. Sediment losses and gains across a gradient of livestock grazing and plant invasion in a cool, semi-arid grassland, Colorado Plateau, USA. Aeolian Research 1:27–43.
Breshears, D. D., J. J. Whicker, C. B. Zou, J. P. Field, and C. D. Allen. 2009. A conceptual framework for dryland aeolian sediment transport along the grassland-forest continuum: Effects of woody plant canopy cover and disturbance. Geomorphology 105: 28-38.
Fung, I.Y., Meyn, S.K., Tegen, I., Doney, S.C., John, J.G., Bishop, J.K.B., 2000. Iron supply and demand in the upper ocean. Global Biogeochemical Cycles 14, 281–295.
Koren, I., Kaufman, Y.J., Washington, R., Todd, M.C., Rudich, Y., Martins, J.V., Rosenfeld, D., 2006. The Bodélé depression: a single spot in the Sahara that provides most of the mineral dust to the Amazon forest. Environmental Research Letters 1, 0140055.
Mahowald, N.M., Kloster, S., Engelstaedter, S., Moore, J.K., Mukhopadhyay, S., McConnell, J.R., Albani, S., Doney, S.C., Bhattacharya, A., Curran, M.A.J., Flanner, M.G., Hoffman, F.M., Lawrence, D.M., Lindsay, K., Mayewski, K.A., Neff, J., Rothenberg, D., Thomas, E., Thornton, P.E., Zender, C.S., 2010. Observed 20th century desert dust variability: impact on climate and biogeochemistry. Atmospheric Chemistry and Physics 10, 10875–10893.
Neff, J. C., R. L. Reynolds, J. Belnap, and P. Lamothe. 2005. Multi-decadal impacts of grazing on soil physical and biogeochemical properties in southeast Utah. Ecological Applications 15:87–95.
Saturday, May 14, 2011
It was found in my old stomping grounds of Grand Staircase-Escalante National Monument near the contact between the Wahweap formation and the Kaiparowits formation. The fossil was located near Cottonwood Canyon where I would often camp in the shade after long hot days of hiking to remote sampling sites, and attempt to remove the multi-day sunscreen & soil crust that had accumulated on me in the nearby creek. The sandstone portions of the Wahweap formation can support some very nice biocrust today if you work harder than a cow and walk far away from water sources. So needless to say this stirs some nostalgia in me. Little did I know there were fossil crusts in the rocks, it really makes you wonder what other formations have them.
As you can see from the photos, they have a pinnacled structure like most of the Colorado Plateau crusts of today. This puzzles me a bit, we have long thought that frost heaving plays a large part in generating uplift in these pinnacled crusts. Naturally, erosion sculpts things that stick up, but eventually some equilibrium is found where the sculpted pinnacled form is well-preserved by a late successional biocrust. But the Cretaceous was a much warmer time than today, the areas where the rocks were formed would not likely have experienced frost, correct me if I’m wrong. I was similarly puzzled a few years ago when I saw a fantastic crust on the Oregon Dunes while cycle touring. It had the exact same pinnacled structure as Colorado Plateau crusts, despite the maritime climate and lack of frost. Maybe we need to rethink the origin of this structure.
Read more about the fossil crust here. All photos are from Simpson et al. 2010.
Simpson, W.S., Simpson, E.L., Wizevich, M.C., Malenda, H.F., Hillbert-Wolf, A.L., Tindall, S.E. 2010. A preserved Late Cretaceous biological soil crust in the capping sandstone member,Wahweap Formation, Grand Staircase-Escalante National Monument, Utah: Paleoclimatic implications. Sedimentary Geology 230: 139-145.
Sunday, May 8, 2011
Check out their post "The Living Wall", containing more photos and some info about the crusts provided by Dave Eldridge.
This is my attempt at creating an open conduit for networking among the growing, but still small number of researchers that can’t seem to stop studying biological soil crusts. We have a fondness for the things that other scientists can’t seem to notice. I started working on crusts because I love deserts and kept noticing these things on the soil while doing, e.g. tortoise surveys, or looking at (yawn!!) plants. My co-workers often sort of knew what they were called (crypto-somethings), but most people were at a loss to explain them. I was enthralled, they were black, white, yellow and pink, a coral reef in the Mojave desert. Fifteen or so years later, the fascination has been an endless well. I don’t think I’m alone. I heard Burk Budel give a talk and he mentioned a real-life generic name that speaks directly to this plight…Geodermatophilus. The love of the skin of the Earth might be called Geodermatophilia.
This site will be a source of information, especially for students just getting started. Hopefully finding information on biocrusts will be made much easier than it was for me, much much easier than it was for Jayne Belnap or Dave Eldridge, and much much much easier than it was for Rod Rogers, Otto Lange or Kimball Harper. My idea is to develop a blog as a fluid centerpiece. I would very much like this to evolve into our blog , in the sense of an international network of bloggers. I will periodically be recruiting new posters, especially younger ones. I will also be constructing a directory of links to biocrust researchers of the world, and may attempt to create a biocrust bibliography. This site will be a relaxed and informal source for information about meetings and conferences, new literature, and sharing of observations, photos, information, ideas, etc.
This post is an invitation to read, comment, and contribute.