苔藓植物对植物天然更新的影响

种子是天然更新的基础,幼苗和幼树的生长是天然更新过程中最敏感的阶段。苔藓植物作为许多生态系统的主要地被物,在维管植物天然更新过程中发挥着不容忽视的作用。在许多植被类型中,都有发育良好的苔藓群落,大量的研究证明它们的存在影响到维管植物的萌发、建成和生长,并且可能进一步影响到物种的共生,有一些种类甚至可能指示树种的更新。本文就苔藓植物对物种更新早期阶段的作用和影响进行了综述。包括苔藓植物的生理特性造成的微气候变化;苔藓群落对种子传播、萌发及幼苗建成的影响。并讨论了苔藓植物与更新物种的种间关系及其对幼苗生长的化感作用。     

Vascular Plants Facilitated Bryophytes in a Grassland Experiment

In grassland communities vascular plants and bryophytes form two distinct layers. In order to understand the factors responsible for plant community structure, more information about interactions between these plant groups is needed. Often negative correlations between vascular plant and bryophyte covers have been reported, suggesting competition. Here we tested experimentally whether different grassland vascular plant species (Trifolium pratense, Festuca pratensis, Prunella vulgaris) had different influences on the cover of two bryophyte species (Rhytidiadelphus squarrosus, Brachythecium rutabulum). In a two-year garden pot experiment one bryophyte species and one vascular plant species were planted per pot. Bryophytes were planted at a constant density, vascular plants in four densities. The cover of both bryophyte species increased with increasing vascular plant cover, showing the facilitative effect of vascular plants through creating better microclimate, e.g., optimising temperature. Bryophyte responses to vascular plant species were species-specific. Festuca had significantly positive effects on both bryophyte species in the second year, and Trifolium on Brachythecium in both years, whereas Prunella had no significant effect on bryophytes. The facilitative effect of vascular plants was stronger at the second experimental year. In summary, the biotic effects between bryophytes and grassland vascular plants are species-specific and positive interactions are prevailing at low vascular plant densities.     

Bryophyte and vascular plant species richness in boreo-nemoral moist forests and mires

We compare species richness of bryophytes and vascular plants in Estonian moist forests and mires. The material was collected from two wetland nature reserves. Bryophyte and vascular plant species were recorded in 338 homogeneous stands of approximately 1 ha in nine forest and two mire types. Regional species pools for bryophytes and vascular plants were significantly correlated. The correlations between the species richnesses of bryophytes and vascular plants per stand were positive in all community types. The relative richnesses (local richness divided by the regional species pool size) were similar for bryophyte species and for vascular plant species. This shows that on larger scales, conservation of the communities rich in species of one taxonomic plant group, maintains also the species richness of the other. The minimum number of stands needed for the maintenance of the regional species pool of typical species for the every community type was calculated using the species richness accumulation curves. Less stands are needed to maintain the bryophyte species pools (300–5300 for bryophytes and 400–35 000 for vascular plants).     

How do bryophytes govern generative recruitment of vascular plants?

Interactions between vascular plants and bryophytes determine plant community composition in many ecosystems. Yet, little is known about the importance of interspecific differences between bryophytes with respect to their effects on vascular plants. We compared the extent to which species-specific bryophyte effects on vascular plant generative recruitment depend on the following underlying mechanisms: allelopathy, mechanical obstruction, soil moisture and temperature control. We sowed 10 vascular plant species into monospecific mats of six chemically and structurally diverse bryophytes, and examined 1-yr seedling recruitment. Allelopathic effects were also assessed in a laboratory phyto-assay. Although all bryophytes suppressed vascular plant regeneration, there were significant differences between the bryophyte species. The lack of interactions indicated the absence of species-specific adaptations of vascular plants for recruitment in bryophyte mats. Differences between bryophyte species were best explained by alterations in temperature regime under bryophyte mats, mostly by reduced temperature amplitudes during germination. The temperature regime under bryophyte mats was well predicted by species-specific bryophyte cushion thickness. The fitness of established seedlings was not affected by the presence of bryophytes. Our results suggest that climatically or anthropogenically driven changes in the species' composition of bryophyte communities have knock-on effects on vascular plant populations via generative reproduction.     

Species richness of vascular plants, bryophytes and lichens in dry grasslands: The effects of environment, landscape structure and competition

We studied the relative importance of local habitat conditions and landscape structure for species richness of vascular plants, bryophytes and lichens in dry grasslands on the Baltic island of Öland (Sweden). In addition, we tested whether relationships between species richness and vegetation cover indicate that competition within and between the studied taxonomic groups is important. We recorded species numbers of vascular plants, bryophytes and lichens in 4 m² plots (n=452), distributed over dry grassland patches differing in size and degree of isolation. Structural and environmental data were collected for each plot. We tested effects of local environmental conditions, landscape structure and vegetation cover on species richness using generalized linear mixed models. Different environmental variables explained species richness of vascular plants, bryophytes and lichens. Environmental effects, particularly soil pH, were more important than landscape structure. Interaction effects of soil pH with other environmental variables were significant in vascular plants. Plot heterogeneity enhanced species richness. Size and degree of isolation of dry grassland patches significantly affected bryophyte and lichen species richness, but not that of vascular plants. We observed negative relationships between bryophyte and lichen species richness and the cover of vascular plants. To conclude, effects of single environmental variables on species richness depend both on the taxonomic group and on the combination of environmental factors on a whole. Dispersal limitation in bryophytes and lichens confined to dry grasslands may be more common than is often assumed. Our study further suggests that competition between vascular plants and cryptogams is rather asymmetric.     

Bryophyte colonisation in experimental microcosms: the role of nutrients, defoliation and vascular vegetation

A three-year multi-factorial microcosm experiment simulating fertilisation, defoliation and the composition of vascular vegetation in a dry grassland succession was used to test four hypotheses concerning the establishment and survival of bryophytes in grassland vegetation. H₁: bryophyte cover may be used to predict bryophyte species richness. H₂: bryophyte richness is suppressed at high nutrient levels and promoted by defoliation of vascular plants. H₃: species richness of bryophytes is influenced by the species composition of the vascular vegetation. H₄: bryophyte species richness is negatively correlated with vascular plant biomass.
The relationship between bryophyte richness and bryophyte cover was found to follow the classical species-area richness curve. Bryophyte species richness responded positively to defoliation and negatively to fertilisation. The species composition of vascular vegetation had no significant effect on bryophyte richness. Bryophyte species richness was lower at high vascular plant biomass and vascular plant dry weight above 400 g m⁻² appeared fatal to bryophytes. At high nutrient levels, defoliation increased bryophyte richness, but defoliation did not fully compensate for the negative effect of fertilisation. The study reinforces the concern for short lived shuttle bryophytes in the agricultural landscape.     

Is vascular plant species diversity a predictor of bryophyte species diversity in Mediterranean forests?

This study aimed to (i) investigate the congruence among the species composition and diversity of bryophytes and vascular plants in forests; (ii) test if site prioritization for conservation aims by the maximization of the pooled number of vascular plant species is effective to maximize the pooled number of bryophyte species. The study was performed in six forests in Tuscany, Italy. Four-hundred and twenty vascular plant species (61 of which were woody) and 128 bryophyte species were recorded in 109 plots. Despite the good predictive value of the compositional patterns of both woody plants and total vascular with respect to the compositional pattern of bryophytes, the species richness of the latter was only marginally related to the species richness of the former two. Bryophyte rare species were not spatially related to rare plant species and neither coincided with the sites of highest plant species richness. The species accumulation curves of bryophytes behaved differently with respect to those of woody plants or total vascular plants. Reserve selection analysis based on the maximization of the pooled species richness of either woody plants or total vascular plants were not effective in maximizing the pooled species richness of bryophytes. This study indicates that species diversity of vascular plants is not likely to be a good indicator of the bryophyte species diversity in Mediterranean forests.     

Bryophyte vegetation in a wooded meadow: relationships with phanerogam diversity and responses to fertilisation

In the Laelatu wooded meadow in Estonia, famous for its phanerogam diversity, the bryophyte community has been investigated in order to compare its flora and diversity relationships with those of the vascular plant community. Ninety-six bryophyte species were found, 13 of them are hepatics; the majority of the bryophytes are epigeic species common to meadows and forests, including many calciphilous species. Vascular plants and bryophytes display opposite responses to fertilisation. For vascular plants, fertilisation increases the coverage and diminishes the number of species, while for bryophytes it diminishes coverage and increases the number of species. The relationship between the number of species in small plots and the total number of species in the area is similar for vascular plants and bryophytes. No significant changes in the bryophyte community in Laelatu wooded meadow has been detected during the last 30 years.     

Selecting important areas for bryophyte conservation: Is the higher taxa approach an effective method?

Surrogates have been used as a support for conservation practices, since they are easier to assess and less time consuming than collecting species-level data. One of these surrogates is the “higher taxa approach”, i.e., the use of data with coarser taxonomic resolution than the species level, such as genus and family levels, as a surrogate for total species richness.The aim of this work was to test if higher taxa (Genera) could be used in the selection of important areas for bryophyte conservation, using three different methodological approaches: Scoring, Important Plant Areas and Complementarity-based approach. We tested these approaches in a protected area, the Peneda-Gerês National Park, one of the best studied areas in Portugal for bryophytes and one of the first areas in the country with bryophyte collections. The knowledge of bryophyte distribution in this National Park has been increasing and distribution maps and detailed species lists were recently published, so we thought it would be a good area to test if the higher taxa approach is an effective method for selecting important areas for bryophyte conservation.Our results showed that localities were ranked in a similar way using species or genera data, regardless of the methodology used. The Complementarity-based approach in comparison with other methodologies protected a higher percentage of bryophyte species.In general, the three approaches identified the same areas as important areas for bryophyte conservation. Therefore, for the studied area and independently of the approach used, genera could be used in the selection of important areas for bryophyte conservation.     

Loss of habitat specialists despite conservation management in fen remnants 1995–2006

Many ecosystems of high conservation value have been shaped by human impacts over centuries. Today, traditional management of semi-natural habitats is a common conservation measure in Europe. However, despite traditional management, habitat remnants may still loose specialist species due to surrounding land-use change or atmospheric nitrogen deposition. To detect trends in species density (2-m² plot scale) and habitat quality in calcareous fens in the pre-Alps of Switzerland, we surveyed 36 traditionally managed fens in 1995/97 and again in 2005/06 (five plots per fen). The fens occurred at three altitudinal levels (800–1000, 1000–1200, 1200–1400 m asl) and were either extensively grazed or mown once a year. Despite these traditional management regimes, species density of fen specialists and of all bryophytes decreased during this decade (vascular plant specialists: ?9.4%, bryophyte specialists: ?14.9%, all bryophytes: ?5.7%). Management had no effect on the number of Red-List species and habitat specialists of vascular plants per plot. However, bryophyte species density was more strongly reduced in grazed fens. Species density of vascular plant generalists increased between the two surveys (+8.2%) but not of bryophytes. Among vascular plants, Red-List species decreased from 1.01 to 0.78 species per plot. Furthermore, between the two surveys aboveground plant biomass, mean plant-community indicator values for nutrients and species density of nutrient indicators increased, whereas mean plant indicator values for soil moisture, light and peat, and species density for peat indicators, decreased. We attribute these changes and the loss of specialist species over the past decade mainly to land-use change in the surrounding area and to nutrient inputs. Thus, despite traditional management, calcareous fens in the pre-Alps suffer from ongoing habitat deterioration and endangered plant species remain threatened. For their long-term protection, we suggest to reduce nutrient inputs and, where necessary, to restore hydrology and adjust grazing management.     

Phytohormone Profiling across the Bryophytes

BackgroundBryophytes represent a very diverse group of non-vascular plants such as mosses, liverworts and hornworts and the oldest extant lineage of land plants. Determination of endogenous phytohormone profiles in bryophytes can provide substantial information about early land plant evolution. In this study, we screened thirty bryophyte species including six liverworts and twenty-four mosses for their phytohormone profiles in order to relate the hormonome with phylogeny in the plant kingdom.MethodologySamples belonging to nine orders (Pelliales, Jungermanniales, Porellales, Sphagnales, Tetraphidales, Polytrichales, Dicranales, Bryales, Hypnales) were collected in Central and Northern Bohemia. The phytohormone content was analysed with a high performance liquid chromatography electrospray tandem-mass spectrometry (HPLC-ESI-MS/MS).ConclusionThe apparent differences in conjugation and/or degradation strategies of growth hormones between liverworts and mosses might potentially show a hidden link between vascular plants and liverworts. On the other hand, the complement of stress hormones in bryophytes probably correlate rather with prevailing environmental conditions and plant survival strategy than with plant evolution.     

Distribution and floristics of moss- and lichen-dominated soil crusts in a patterned Callitris glaucophylla woodland in eastern Australia

The distribution and abundance of soil crust lichens and bryophytes was examined in a patterned Callitris glaucophylla woodland in eastern Australia. Twenty-one lichen species and 26 bryophyte species were collected within thirty quadrats along a sequence of runoff, interception and runoff zones. Crust cover was significantly greatest in the interception zones (79.0 %), followed by the runoff zones (24.0 %), and lowest in the groved, runon zones (6.6 %). Lichens and bryophytes were distributed across all geomorphic zones, and, although there were significantly more moss species in the interception zones (mean = 9.1) compared with either the runoff (4.2) or runon (3.2) zones, the number of lichen species did not vary between zones. Ordination of a reduced data set of 32 species revealed a separation of taxa into distinct groups corresponding to the three geomorphic zones. Canonical correspondence analysis (CCA) of the 32 species and thirteen environmental variables revealed that the most important factors associated with the distribution of species were sheet and scarp erosion, soil stability and coherence, litter cover and crust cover. Surface cracking, microtopography and plant cover were of intermediate importance. The CCA biplot revealed that the timbered runon zones (groves) were dominated by `shade-tolerant' mosses Fissidens vittatus and Barbula hornschuchiana, whilst the heavily eroded runoff zones supported sparse populations of `erosion tolerant' lichens (Endocarpon rogersii) and mosses (Bryum argenteum and Didymodon torquatus). Interception zones supported a rich suite of `crust forming' mosses and lichens capable of tolerating moderate inundation by overland flow. Two other groups of taxa were identified by this analysis: the `pioneer' group, comprising mainly nitrogen-fixing lichens which occupy the zone of active erosion at the lower edge of the groves, and the `opportunists' dominated by liverworts, occupying the shallow depressions or bays at the margins of the groves and the interception zones. This study confirms that the non-vascular lichens and bryophytes in these arid soil crusts, are, like the vascular plants, strongly patterned according to geomorphic zone, being most strongly associated with soil surface and erosional features.     

The phylogeny of land plants: A cladistic analysis based on male gametogenesis

A cladistic analysis was carried out to resolve phylogenetic pattern among bryophytes and other land plants. The analysis used 22 taxa of land plants and 90 characters relating to male gametogenesis.Coleochaete orChara/Nitella were the outgroups in various analyses using HENNIG86, PAUP, and MacClade, and the land plant phylogeny was unchanged regardless of outgroup utilized. The most parsimonious cladograms from HENNIG86 (7 trees) have treelengths of 243 (C.I. = 0.58, R.I. = 0.82). Bryophytes are monophyletic as are hornworts, liverworts, and mosses, with hornworts identified as the sister group of a liverwort/moss assemblage. In vascular plants, lycophytes are polyphyletic andSelaginella is close to the bryophytes.Lycopodium is the sister group of the remaining vascular plants (minusSelaginella). Longer treelengths (over 250) are required to produce tree topologies in which either lycophytes are monophyletic or to reconstruct the paraphyletic bryophyte phylogeny of recent authors. This analysis challenges existing concepts of bryophyte phylogeny based on more classical data and interpretations, and provides new insight into land plant evolution.     

Vascular plant and bryophytes species representation in the protected areas network on the national scale

The complexity of nature conservation raises questions about biodiversity protection at the level of species as well as their spatial distribution between differently designated nature conservation areas. We have concentrated on comparison of the existing protected areas and recently established conservation initiative areas—Important Plant Areas. We have estimated how well these areas support the protection of two plant groups—bryophytes and vascular plants. We sought answers to the following questions: (a) are there any trends in the distribution of protected bryophyte and vascular plant species in the protected areas network, and (b) does the Important Plant Areas network promote better protection of bryophyte species compared with the existing protected areas network. Our results demonstrated that bryophytes need special care in nature conservation decisions to reach the reasonable conservation target. Important Plant Areas that were targeted to vascular plants have less importance in preserving bryophyte diversity than already existing conservation areas system. Conservation programs like IBA, IPA etc. have their specific tool and outcome to add conservation values to the existing protected areas system.     

Endozoochory by slugs can increase bryophyte establishment and species richness

Herbivory can affect plant community composition and diversity by removing biomass and reducing light competition. Herbivory may particularly benefit low growing species such as bryophytes, which are frequently limited by light competition. Gastropods are important herbivores of seed plants and cryptogams, furthermore, they can disperse propagules such as seeds and spores via endozoochory. However, whether gastropod herbivory can reduce the dominance of vascular plants and thereby promote the germination and establishment of endozoochorously dispersed bryophyte spores has never been tested experimentally. Moreover, it is unclear whether these possible interacting effects can influence bryophyte species richness. Here, we tested for endozoochorous spore dispersal by slugs, in combination with sowing of vascular plants, in a fully factorial common garden experiment. Enclosures contained either slugs previously fed with bryophyte sporophytes, control slugs, or no slugs. After 21 days the bryophyte cover was on average 2.8 times higher (3.9% versus 1.4%) and after eight months the bryophyte species richness 2.6 times higher (5.8 versus 2.2) in enclosures containing slugs previously fed with bryophyte sporophytes than in the other treatments. Furthermore, after eight months high vascular plant cover reduced bryophyte diversity. On average enclosures without seed sowing harboured 1.6 times more bryophyte species than the ones with seed sowing (4.2 versus 2.6), indicating competitive effects of vascular plants on bryophytes. Our findings suggest that slugs are important dispersal vectors for bryophytes and that they can increase bryophyte populations and maintain bryophyte diversity by reducing the dominance of vascular plants.     

Impact of Land-Use Intensity and Productivity on Bryophyte Diversity in Agricultural Grasslands

While bryophytes greatly contribute to plant diversity of semi-natural grasslands, little is known about the relationships between land-use intensity, productivity, and bryophyte diversity in these habitats. We recorded vascular plant and bryophyte vegetation in 85 agricultural used grasslands in two regions in northern and central Germany and gathered information on land-use intensity. To assess grassland productivity, we harvested aboveground vascular plant biomass and analyzed nutrient concentrations of N, P, K, Ca and Mg. Further we calculated mean Ellenberg indicator values of vascular plant vegetation. We tested for effects of land-use intensity and productivity on total bryophyte species richness and on the species richness of acrocarpous (small & erect) and pleurocarpous (creeping, including liverworts) growth forms separately. Bryophyte species were found in almost all studied grasslands, but species richness differed considerably between study regions in northern Germany (2.8 species per 16 m²) and central Germany (6.4 species per 16 m²) due environmental differences as well as land-use history. Increased fertilizer application, coinciding with high mowing frequency, reduced bryophyte species richness significantly. Accordingly, productivity estimates such as plant biomass and nitrogen concentration were strongly negatively related to bryophyte species richness, although productivity decreased only pleurocarpous species. Ellenberg indicator values for nutrients proved to be useful indicators of species richness and productivity. In conclusion, bryophyte composition was strongly dependent on productivity, with smaller bryophytes that were likely negatively affected by greater competition for light. Intensive land-use, however, can also indirectly decrease bryophyte species richness by promoting grassland productivity. Thus, increasing productivity is likely to cause a loss of bryophyte species and a decrease in species diversity.     

Bryophyte communities in mesotrophic fens in the Netherlands

Seven bryophyte and three vascular plant community types were described from eight small fens in the Vechtplassen area (prov. of Utrecht, the Netherlands). Clear relationships between the species composition of the bryophyte and vascular plant layer were found. The bryophyte species composition shows a gradual change from quaking fens dominated by Calliergon cordifolium to fens dominated by several species of Sphagnum . Fens dominated by C. cordifolium have relatively high pH and conductivity values and are strongly quaking, whereas fens dominated by Sphagnum have relatively low pH and conductivity values and the peat layer is continuous down to the bottom sediment. A comparison of the present-day vegetation with an earlier successional scheme for this vegetation type (Segal 1966) indicates a raise in nutrient levels and a decrease in the amount of seepage water welling up at the sites, both due to human activities. We suggest that in early successional phases bryophytes react faster to these changes, whereas in later phases vascular plants react faster.     

植物激素在苔藓生长发育与逆境响应过程中的作用机制研究进展

植物激素是由植物自身代谢产生的一类从产生部位移动到作用部位发挥调控功能的微量小分子有机物质,在植物生长发育、响应环境胁迫过程中起到关键作用.苔藓植物作为早期登陆的非维管植物,处于陆生植物进化早期的阶段,具有许多不同于维管植物的形态和生理特征.大部分苔藓中普遍存在8种主要的植物激素及其衍生物(包括ABA、JA、ET、SA...     

Chloroplast phylogeny indicates that bryophytes are monophyletic

Opinions on the basal relationship of land plants vary considerably and no phylogenetic tree with significant statistical support has been obtained. Here, we report phylogenetic analyses using 51 genes from the entire chloroplast genome sequences of 20 representative green plant species. The analyses, using translated amino acid sequences, indicated that extant bryophytes (mosses, liverworts, and hornworts) form a monophyletic group with high statistical confidence and that extant bryophytes are likely sisters to extant vascular plants, although the support for monophyletic vascular plants was not strong. Analyses at the nucleotide level could not resolve the basal relationship with statistical confidence. Bryophyte monophyly inferred using amino acid sequences has a good statistical foundation and is not rejected statistically by other data sets. We propose bryophyte monophyly as the currently best hypothesis.