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Ulf Molau - One of the best experts on this subject based on the ideXlab platform.
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Climate change and climatic events: community-, functional- and species-level responses of Bryophytes and lichens to constant, stepwise, and pulse experimental warming in an alpine tundra
Alpine Botany, 2014Co-Authors: Juha M Alatalo, Annika K Jagerbrand, Ulf MolauAbstract:We experimentally imposed three different kinds of warming scenarios over 3 years on an alpine meadow community to identify the differential effects of climate warming and extreme climatic events on the abundance and biomass of Bryophytes and lichens. Treatments consisted of (a) a constant level of warming with open top chambers (an average temperature increase of 1.87 °C), (b) a yearly stepwise increase of warming (average temperature increases of 1.0; 1.87 and 3.54 °C, consecutively), and (c) a pulse warming, i.e., a single first year pulse event of warming (average temperature increase of 3.54 °C only during the first year). To our knowledge, this is the first climate change study that attempts to distinguish between the effects of constant, stepwise and pulse warming on Bryophyte and lichen communities. We hypothesised that pulse warming would have a significant short-term effect compared to the other warming treatments, and that stepwise warming would have a significant mid-term effect compared to the other warming treatments. Acrocarpous Bryophytes as a group increased in abundance and biomass to the short-term effect of pulse warming. We found no significant effects of mid-term (third-year) stepwise warming. However, one pleurocarpous Bryophyte species, Tomentypnum nitens, generally increased in abundance during the warm year 1997 but decreased in control plots and in response to the stepwise warming treatment. Three years of experimental warming (all treatments as a group) did have a significant impact at the community level, yet changes in abundance did not translate into significant changes in the dominance hierarchies at the functional level (for acrocarpous Bryophytes, pleurocarpous Bryophytes, Sphagnum or lichens), or in significant changes in other Bryophyte or lichen species. The results suggest that Bryophytes and lichens, both at the functional group and species level, to a large extent are resistant to the different climate change warming simulations that were applied.
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Bryophyte and lichen diversity under simulated environmental change compared with observed variation in unmanipulated alpine tundra
Biodiversity and Conservation, 2006Co-Authors: Annika K Jagerbrand, Karin Lindblad, Robert G Bjork, Juha M Alatalo, Ulf MolauAbstract:Effects of simulated environmental change on Bryophyte and lichen species richness and diversity in alpine tundra were investigated in a 5-year experiment at Latnjajaure, northern Sweden. The experiment had a factorial design including fertilisation and temperature enhancement in one meadow and one heath plant community. Responses in species richness, biodiversity, and species composition of Bryophytes and lichens to experimental treatments were compared to the observed variation in six naturally occurring plant communities. The combination of fertilisation and enhanced temperature resulted in a species impoverishment, for Bryophytes in the Bryophyte-dominated community, and for lichens in the lichen-dominated communities, but the species composition stayed within the observed natural variation. During the course of the study, no species new to the investigated mid-alpine landscape were recorded, but that scenario is realistic within a decade when comparing with the processes seen in vascular plants.
John England - One of the best experts on this subject based on the ideXlab platform.
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regeneration of little ice age Bryophytes emerging from a polar glacier with implications of totipotency in extreme environments
Proceedings of the National Academy of Sciences of the United States of America, 2013Co-Authors: Catherine La Farge, Krista H Williams, John EnglandAbstract:Across the Canadian Arctic Archipelago, widespread ice retreat during the 20th century has sharply accelerated since 2004. In Sverdrup Pass, central Ellesmere Island, rapid glacier retreat is exposing intact plant communities whose radiocarbon dates demonstrate entombment during the Little Ice Age (1550–1850 AD). The exhumed Bryophyte assemblages have exceptional structural integrity (i.e., setae, stem structures, leaf hair points) and have remarkable species richness (60 of 144 extant taxa in Sverdrup Pass). Although the populations are often discolored (blackened), some have developed green stem apices or lateral branches suggesting in vivo regrowth. To test their biological viability, Little Ice Age populations emerging from the ice margin were collected for in vitro growth experiments. Our results include a unique successful regeneration of subglacial Bryophytes following 400 y of ice entombment. This finding demonstrates the totipotent capacity of Bryophytes, the ability of a cell to dedifferentiate into a meristematic state (analogous to stem cells) and develop a new plant. In polar ecosystems, regrowth of Bryophyte tissue buried by ice for 400 y significantly expands our understanding of their role in recolonization of polar landscapes (past or present). Regeneration of subglacial Bryophytes broadens the concept of Ice Age refugia, traditionally confined to survival of land plants to sites above and beyond glacier margins. Our results emphasize the unrecognized resilience of Bryophytes, which are commonly overlooked vis-a-vis their contribution to the establishment, colonization, and maintenance of polar terrestrial ecosystems.
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regeneration of little ice age Bryophytes emerging from a polar glacier with implications of totipotency in extreme
2013Co-Authors: Krista H Williams, John EnglandAbstract:Across the Canadian Arctic Archipelago, widespread ice retreat during the 20th century has sharply accelerated since 2004. In Sverdrup Pass, central Ellesmere Island, rapid glacier retreat is exposing intact plant communities whose radiocarbon dates demonstrate entombment during the Little Ice Age (1550–1850 AD). The exhumed Bryophyte assemblages have exceptional structural integrity (i.e., setae, stem structures, leaf hair points) and have remarkable species richness (60 of 144 extant taxa in Sverdrup Pass). Although the populations are often discolored (blackened), some have developed green stem apices or lateral branches suggesting in vivo regrowth. To test their biological viability, Little Ice Age populations emerging from the ice margin were collected for in vitro growth experiments. Our results include a unique successful regeneration of subglacial Bryophytes following 400 y of ice entombment. This finding demonstrates the totipotent capacity of Bryophytes, the ability of a cell to dedifferentiate into a meristematic state (analogous to stem cells) and develop a new plant. In polar ecosystems, regrowth of Bryophyte tissue buried by ice for 400 y significantly expands our understanding of their role in recolonization of polar landscapes (past or present). Regeneration of subglacial Bryophytes broadens the concept of Ice Age refugia, traditionally confined to survival of land plants to sites above and beyond glacier margins. Our results emphasize the unrecognized resilience of Bryophytes, which are commonly overlooked vis‐a‐vis their contribution to the establishment, colonization, and maintenance of polar terrestrial ecosystems.
Juan Carlos Villarreal - One of the best experts on this subject based on the ideXlab platform.
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organellomic data sets confirm a cryptic consensus on unrooted land plant relationships and provide new insights into Bryophyte molecular evolution
American Journal of Botany, 2020Co-Authors: David Bell, Carl J Rothfels, Qianshi Lin, Wesley K Gerelle, Steve Joya, Ying Chang, Nathan Z Taylor, Anders Larsson, Juan Carlos VillarrealAbstract:Premise Phylogenetic trees of Bryophytes provide important evolutionary context for land plants. However, published inferences of overall emBryophyte relationships vary considerably. We performed phylogenomic analyses of Bryophytes and relatives using both mitochondrial and plastid gene sets, and investigated Bryophyte plastome evolution. Methods We employed diverse likelihood‐based analyses to infer large‐scale Bryophyte phylogeny for mitochondrial and plastid data sets. We tested for changes in purifying selection in plastid genes of a mycoheterotrophic liverwort (Aneura mirabilis) and a putatively mycoheterotrophic moss (Buxbaumia), and compared 15 Bryophyte plastomes for major structural rearrangements. Results Overall land‐plant relationships conflict across analyses, generally weakly. However, an underlying (unrooted) four‐taxon tree is consistent across most analyses and published studies. Despite gene coverage patchiness, relationships within mosses, liverworts, and hornworts are largely congruent with previous studies, with plastid results generally better supported. Exclusion of RNA edit sites restores cases of unexpected non‐monophyly to monophyly for Takakia and two hornwort genera. Relaxed purifying selection affects multiple plastid genes in mycoheterotrophic Aneura but not Buxbaumia. Plastid genome structure is nearly invariant across Bryophytes, but the tufA locus, presumed lost in emBryophytes, is unexpectedly retained in several mosses. Conclusions A common unrooted tree underlies emBryophyte phylogeny, [(liverworts, mosses), (hornworts, vascular plants)]; rooting inconsistency across studies likely reflects substantial distance to algal outgroups. Analyses combining genomic and transcriptomic data may be misled locally for heavily RNA‐edited taxa. The Buxbaumia plastome lacks hallmarks of relaxed selection found in mycoheterotrophic Aneura. Autotrophic Bryophyte plastomes, including Buxbaumia, hardly vary in overall structure.
Ying Chang - One of the best experts on this subject based on the ideXlab platform.
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organellomic data sets confirm a cryptic consensus on unrooted land plant relationships and provide new insights into Bryophyte molecular evolution
American Journal of Botany, 2020Co-Authors: David Bell, Carl J Rothfels, Qianshi Lin, Wesley K Gerelle, Steve Joya, Ying Chang, Nathan Z Taylor, Anders Larsson, Juan Carlos VillarrealAbstract:Premise Phylogenetic trees of Bryophytes provide important evolutionary context for land plants. However, published inferences of overall emBryophyte relationships vary considerably. We performed phylogenomic analyses of Bryophytes and relatives using both mitochondrial and plastid gene sets, and investigated Bryophyte plastome evolution. Methods We employed diverse likelihood‐based analyses to infer large‐scale Bryophyte phylogeny for mitochondrial and plastid data sets. We tested for changes in purifying selection in plastid genes of a mycoheterotrophic liverwort (Aneura mirabilis) and a putatively mycoheterotrophic moss (Buxbaumia), and compared 15 Bryophyte plastomes for major structural rearrangements. Results Overall land‐plant relationships conflict across analyses, generally weakly. However, an underlying (unrooted) four‐taxon tree is consistent across most analyses and published studies. Despite gene coverage patchiness, relationships within mosses, liverworts, and hornworts are largely congruent with previous studies, with plastid results generally better supported. Exclusion of RNA edit sites restores cases of unexpected non‐monophyly to monophyly for Takakia and two hornwort genera. Relaxed purifying selection affects multiple plastid genes in mycoheterotrophic Aneura but not Buxbaumia. Plastid genome structure is nearly invariant across Bryophytes, but the tufA locus, presumed lost in emBryophytes, is unexpectedly retained in several mosses. Conclusions A common unrooted tree underlies emBryophyte phylogeny, [(liverworts, mosses), (hornworts, vascular plants)]; rooting inconsistency across studies likely reflects substantial distance to algal outgroups. Analyses combining genomic and transcriptomic data may be misled locally for heavily RNA‐edited taxa. The Buxbaumia plastome lacks hallmarks of relaxed selection found in mycoheterotrophic Aneura. Autotrophic Bryophyte plastomes, including Buxbaumia, hardly vary in overall structure.
Timo Muotka - One of the best experts on this subject based on the ideXlab platform.
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Aquatic Bryophytes play a key role in sediment-stressed boreal headwater streams
Hydrobiologia, 2020Co-Authors: Jarno Turunen, Timo Muotka, Jukka AroviitaAbstract:Forestry-related land use can cause increasing instream sedimentation, burying and eradicating stream Bryophytes, with severe ecological consequences. However, there is limited understanding of the relative roles and overall importance of the two frequently co-occurring stressors, increased fine sediments and loss of Bryophytes, to stream biodiversity and ecosystem functions. By using random forest modeling and partial dependence functions, we studied the relative importance of stream Bryophytes and fine sediments to multiple biological endpoints (leaf-decaying fungi, diatom, Bryophyte, and benthic macroinvertebrate communities; leaf decomposition) using field survey data from headwater streams. Stream Bryophyte abundance and richness were negatively related to fine sediment cover, highlighting the detrimental effect of sedimentation on Bryophytes. However, Bryophyte abundance was consistently more important a determinant of variation in community composition than was fine sediment cover. Leaf decomposition was influenced by shredder abundance, water temperature and, to a lesser degree, stream size. Our results suggest that the loss of stream Bryophytes due to increasing sedimentation, rather than fine sediments per se, seems to be the key factor affecting multiple biological responses. Enhancing the re-establishment of Bryophyte stands could partly compensate for the negative impacts of sedimentation on Bryophytes and, consequently, on several other components of boreal stream ecosystems.
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community concordance between Bryophyte and insect assemblages in boreal springs a broad scale study in isolated habitats
Freshwater Biology, 2009Co-Authors: Risto Virtanen, Jari Ilmonen, Lauri Paasivirta, Timo MuotkaAbstract:SUMMARY 1. We examined species–environment relationships and community concordance between aquatic Bryophytes and insects in boreal springs. We sampled Bryophytes (Marchantiophyta and Bryophyta), benthic macroinvertebrates and environmental variables in 138 springs in Finland, spanning a latitudinal gradient of 1000 km. Macroinvertebrates were subdivided into two groups: Ephemeroptera, Plecoptera, Trichoptera and Coleoptera (EPTC taxa) and chironomid midges (Diptera; Chironomidae). Our aim was to test whether EPTC taxa could be used as surrogates in biodiversity surveys and bioassessment for the two less-well known organism groups, chironomids and Bryophytes. 2. Bryophyte assemblages were clearly differentiated along gradients in thermal conditions and water chemistry (pH, conductivity). Chironomids and EPTC were also differentiated in relation to thermal conditions and, to a lesser extent, physical habitat variables, but were only weakly associated to spring water chemistry. Chironomid and EPTC assemblages were more concordant with each other than with Bryophytes, but all concordances were relatively weak. 3. Our results suggest that even if the overall compositional patterns of the three taxonomic groups were significantly concordant, the relative importance of environmental drivers underlying their community compositions differed strongly. The results thus imply that spring Bryophytes and insects are relatively poor surrogates for each other. The proportion of spring specialists was highest in Bryophytes, promoting their primacy for spring bioassessment and biodiversity conservation. We suggest that adequate variation in water chemistry be assured to protect spring Bryophyte biodiversity, whereas preserving the physical variation of springs is more important for macroinvertebrates.
