tag:blogger.com,1999:blog-8161161431451849208.post8703777865465855604..comments2024-03-18T02:43:22.233-07:00Comments on Antediluvian Salad: The Missing Mesozoic Groundcover: Did Biocrusts Secretly Dominate the Mesozoic?Duane Nashhttp://www.blogger.com/profile/14467779935085970909noreply@blogger.comBlogger5125tag:blogger.com,1999:blog-8161161431451849208.post-1617348388944519782017-09-13T09:26:27.977-07:002017-09-13T09:26:27.977-07:00@Julius thanks for clarification on your study - t...@Julius thanks for clarification on your study - that Ceratodon moss is especially unique and adapted to disturbed environments. Ceratodon does not compare favorably to more "classic" arid land crusts. What I find illuminating is that your study might point to how bio-crusts might respond to trampling stress in more mesic dinosaur dominated habitats. Again, that is why I pointed out the Grand Staircase biocrust, it is interesting because that appears to have been a very mesic environments with lots of standing water/precipitation/very rapid sedimentation rates. It is not typical of where we find soil crusts today!!<br /><br />WHen I look at a trifecta of arguments 1) lack of grass 2) seasonal weather pattern 3) trampling - I am left thinking that other "non-typical" crust like growths held together Mesozoic ecosystems in a manner analogous to your example of Ceratodon moss. Arid land bio-crusts probably most like modern arid land bio-crusts and could tolerate the infrequent trampling that modern biocrusts put up with.<br /><br />Glad to spread the word about biocrusts. IN CRUST WE TRUST!!<br /><br />@Francisco LIra. Thanks for comment. I have commented on such plants in the past. SUch ferns are typical extreme niche species, living in specific sheltered microhabitats in deserts, such as rocky outcrops. I don't see any desert ferns form vast expanses like grasses do. Additionally they are fairly recent fern families, I'd have to review what type but derive from the Cretaceous. I'd love to find evidence of desert ferns of the Triassic and Jurassic but alas. <br /><br />Your point stands that other plants were around in Cretaceous deserts but probably had wide spaces between. Biocrusts could fill the spaces between plants.<br />Duane Nashhttps://www.blogger.com/profile/14467779935085970909noreply@blogger.comtag:blogger.com,1999:blog-8161161431451849208.post-63528033266323804952017-09-12T16:39:42.481-07:002017-09-12T16:39:42.481-07:00in arid environments of Chile there are several sp...in arid environments of Chile there are several species of ferns belonging to the genera Cheilantes and Blechnum, able to live in rock and lava and survive the dry season remaining in relative dormancy. There were probably similar ferns in the Mesozoic that could form grasslands. Neither should we exclude the presence of other gymnosperms of shrub habits capable of covering large areasFrancisco Lirahttps://www.blogger.com/profile/05700870868230695179noreply@blogger.comtag:blogger.com,1999:blog-8161161431451849208.post-27072537471688354162017-09-12T15:48:17.613-07:002017-09-12T15:48:17.613-07:00Thanks for replies and clarifications Julius I wil...Thanks for replies and clarifications Julius I will think about them!Duane Nashhttps://www.blogger.com/profile/14467779935085970909noreply@blogger.comtag:blogger.com,1999:blog-8161161431451849208.post-29110850705255713822017-09-12T14:06:32.043-07:002017-09-12T14:06:32.043-07:00Also, kudos for highlighting a far too poorly noti...Also, kudos for highlighting a far too poorly noticed biological community! The taxonomic composition of biological soil crusts indicates that they were undoubtedly present during the Mesozoic and Paleozoic in the right environments, likely in more physico-chemically stressed environments where competition with vascular plants was somewhat alleviated. I agree that biological soil crusts should be better integrated into paleoart, but paleoartists should also be careful to place them into the most plausible prehistoric microenvironments (e.g., they are present in many arid environments, but they are generally absent on active dunes). In response to your discussion about the possible role of biological soil crusts as sources of food for Mesozoic and Paleozoic animals, I would be hesitant to suggest that they served much of this role for larger animals, except perhaps in unusual situations. For example, you made reference to caribou grazing on lichens; whereas this is a very good example of large herbivores trophically utilizing a group of organisms typically found in some biological soil crusts, it is a highly unusual example too. The Cladonia-dominated lichen fields of the far north fill a niche more like herbaceous understory plants than the soil-stabilizing and more ground-hugging organisms that constitute typical biological soil crusts. Most familiar biological soil crusts are found in arid regions and are more intimately integrated with the soil, making them far more difficult to access for food by large animals trying to avoid a mouthful of sediment in the process. It is conceivable that there were larger moss or lichen thalli growing on some BSC in the distant past, but the harsh conditions under which arid land BSC grow usually results in formations that are more aptly described as crusts than as lawns of organisms that are easily physically separated from the soil substratum. Biological soil crusts may indeed have made up a significant proportion of the biomass in some arid regions of the Mesozoic and Paleozoic, but we should probably be thinking about which small animals (e.g. invertebrates and some very small mammals or reptiles) made use of them for food rather than the larger herbivores.Julius Csotonyihttps://www.blogger.com/profile/04122054942764206623noreply@blogger.comtag:blogger.com,1999:blog-8161161431451849208.post-14554109335330430912017-09-12T13:30:36.386-07:002017-09-12T13:30:36.386-07:00There's an important thing to point out about ...There's an important thing to point out about the influence of trampling on biological soil crusts, since you've cited our paper on elk trampling on a Ceratodon moss dominated soil crust (Csotonyi and Addicott, 2004). This positive effect of trampling that we observed was really an exceptional case, and it should not be taken as representative of the response of biological soil crusts in arid lands, and especially not for moss-dominated soil crusts. Our research was conducted in a relatively mesic location in western Canada compared to the far drier sites on which most of the soil crusts grow that you discuss in this article, making it much easier for the Ceratodon moss to grow rapidly following trampling. Also, Ceratodon purpureus is an unusual moss that specializes on disturbed habitats, and has evolved to grow rapidly through accumulating sediment, often resulting in a thick zone of dead stems below the surface, which is undoubtedly one of the key features that makes it an effective soil stabilizer. The structural integrity thus afforded to dislocated blocks of Ceratodon-dominated soil crust is also key to the understanding why this particular type of soil crust can respond positively to trampling: retention of the deep hoof print impression is necessary to establish and maintain the shaded light regime that facilitates the sheltered microhabitat that enhances growth. It is important to point out that these features of rapid growth and deep thalli are not typically shared by most moss dominated or other types of arid-zone biological soil crusts. In fact, other workers have estimated for arid lands that whereas cyanobacterial soil crusts can recover relatively quickly following fragmentation and crushing by trampling (a few years), moss-dominated soil crusts may take up to 250 years to recover after trampling! They are typically far more fragile and susceptible to trampling disturbance than are Microcoleus-dominated cyanobacterial crusts. The degree of fragility of biological soil crusts is clearly related to a number of factors, including moisture regime, soil composition and texture, and community composition of the soil crust, but I wanted to point out that most soil crusts do not display the kind of response to trampling that we reported for this highly unusual and uncharacteristic type of soil crust community.Julius Csotonyihttps://www.blogger.com/profile/04122054942764206623noreply@blogger.com