Bryophyte community structure in a boreal poor fen II: interspecific competition among five mosses

2002 ◽  
Vol 80 (4) ◽  
pp. 330-339 ◽  
Author(s):  
Roisín C Mulligan ◽  
L Dennis Gignac
Keyword(s):  
Competitive Ability ◽  
Transplant Experiment ◽  
Competitive Effect ◽  
Relative Growth ◽  
Poor Fen ◽  
Feather Mosses ◽  
Sphagnum Fuscum ◽  
Northern Alberta ◽  
Sphagnum Magellanicum ◽  
Study Species

A possible competitive hierarchy among five boreal bryophytes (Sphagnum angustifolium, Sphagnum fuscum, Sphagnum magellanicum, Ptilium crista-castrensis, and Pleurozium schreberi) was examined in a 2-year transplant experiment conducted in two habitats of a poor fen in northern Alberta, Canada, using a sixth moss (Aulacomnium palustre) as a phytometer. Change in relative growth rate in length and weight of A. palustre, measured as competitive effect, indicated the existence of a hierarchy in this peatland wherein the feather mosses are subordinates to the Sphagnum mosses. Relative competitive performance, which was calculated relative to the growth of the phytometer in monoculture, indicated that S. magellanicum exhibited the greatest competitive effect. Sphagnum magellanicum may be a strong competitor and partially inhibit S. fuscum from occupying its full fundamental niche. The competitive ability of S. fuscum and S. angustifolium in this peatland is low relative to that of the other study species. The feather mosses did not demonstrate competitive effect and may have facilitated growth of the phytometer.Key words: bryophyte, competition, feather moss, peatland, phytometer, Sphagnum.

Bryophyte community structure in a boreal poor fen: reciprocal transplants

2001 ◽  
Vol 79 (4) ◽  
pp. 404-411 ◽  
Author(s):  
Roisín C Mulligan ◽  
L Dennis Gignac
Keyword(s):  
Community Structure ◽  
Dry Weight ◽  
Pleurozium Schreberi ◽  
Transplant Experiment ◽  
Reciprocal Transplant Experiment ◽  
Poor Fen ◽  
Reciprocal Transplants ◽  
Sphagnum Fuscum ◽  
Species Tolerance ◽  
Present Distribution

The ability of four boreal bryophytes (Sphagnum angustifolium (C. Jens ex Russ.), Sphagnum fuscum (Schimp.) Klinggr., Sphagnum magellanicum Brid., and Pleurozium schreberi (Brid.) Mitt.) to live in each others' habitats was examined in a 1-year reciprocal transplant experiment conducted in a poor fen peatland in northern Alberta, Canada. Growth in length was determined by measuring increase in shoot length, and growth in dry weight was determined by subtracting final dry weight from initial predicted dry weight. Species tolerance ranges, which approximate to fundamental niches, were determined by the significant differences in growth among the species. Stepwise regression analyses indicated that depth to water was the most important factor for all species except S. fuscum. Pleurozium schreberi exhibited the narrowest potential distribution, indicating that its present distribution is likely the result of habitat limitation. Although S. magellanicum and S. angustifolium exhibited wide potential ecological amplitude, the distributions of these species are partially limited by habitat. Sphagnum fuscum was able to grow in all habitats, and its distribution is not limited by any of the habitat factors measured.Key words: peatland, moss, community structure, Sphagnum, Pleurozium schreberi, niche.

Habitats of circumboreal–subarctic sphagna: I. A quantitative analysis and review of species in the Caribou Mountains, northern Alberta

1979 ◽  
Vol 57 (20) ◽  
pp. 2283-2317 ◽  
Author(s):  
Diana G. Horton ◽  
Dale H. Vitt ◽  
Nancy G. Slack
Keyword(s):  
Quantitative Analysis ◽  
Picea Mariana ◽  
Water Channel ◽  
Bottom Layer ◽  
Relative Importance ◽  
Habitat Types ◽  
Sphagnum Fuscum ◽  
Dense Zone ◽  
Caribou Mountains ◽  
Northern Alberta

A quantitative analysis of the habitats of 14 species of Sphagnum found in the Caribou Mountains of northern Alberta and a literature review are the basis for a discussion of the habitats of these species as they occur in circumboreal–subarctic regions. Despite the implication inherent in the name, the Caribou Mountains are not mountains; the formation is an extensive, elevated plateau, which is underlain by more-or-less continuous permafrost. Three habitat types predominated in our study area: an upland "treed-tundra" (which is dominant over much of the plateau) with scattered Picea mariana and a hummocky bottom layer of sphagna; rounded "thaw-pocket" depressions dominated by carpets of Sphagnum and some carices; and streams defined by a dense zone of shrubs with the narrow water channel bordered by more-or-less firm lawns of Sphagnum species. Three gradients, which are considered to have a predominant influence on the occurrence of Sphagnum species, are wet to dry, ombrotrophic to minerotrophic, and shaded to exposed. The relative importance of each of these factors varies with each species of Sphagnum. Sphagnum jensenii, S. majus, S. riparium, and S. lindbergii occur exclusively in weakly minerotrophic to ombrotrophic, aquatic habitats where populations form loose, floating carpets. Such habitats are generally not much shaded. Such species as S. angustifolium, S. teres, and S. russowii are characteristic of somewhat less moist conditions, but all have a broad amplitude along the ombrotrophic to minerotrophic gradient. However, S. angustifolium is most abundant under poorly minerotrophic conditions where there is less shade, while S. teres predominates under highly minerotrophic conditions and is more-or-less equally tolerant of shade and exposure. Sphagnum warnstorfii apparently is restricted to habitats which are highly minerotrophic, but is tolerant of both shade and exposure. The sphagna most characteristic of densely shaded, woodland habitats where there is little peat development are S. squarrosum, S. wulfianum, and S. girgensohnii. All three species generally form low mounds. Sphagnum fuscum and S. nemoreum form well-defined hummocks and are most prevalent under ombrotrophic conditions.

scholarly journals The competitive ability of Chenopodium album and Echinochloa crus-galli in maize crops depending on the time of their occurrence or removal

2016 ◽  
Vol 69 (4) ◽  
Author(s):  
Hanna Golebiowska ◽  
Renata Kieloch
Keyword(s):  
Competitive Ability ◽  
Stem Elongation ◽  
Chenopodium Album ◽  
Weed Competition ◽  
Growth Stages ◽  
Competitive Effect ◽  
Leaf Stage ◽  
Weed Infestation ◽  
Small Plot ◽  
Weed Emergence

Small-plot experiments for two levels of infestation (20 and 40 plants per m<sup>2</sup>) with <em>Chenopodium album</em> L. and <em>Echinochloa crus-galli</em> (L.) P. Beav were conducted in the 2009–2011 seasons. In the first variant, the effect of time of weed removal on maize was investigated. Weeds were removed in the following growth stages of maize: one, three, five, and seven leaves, the beginning of stem elongation, and the stage from the fourth to sixth node. The second variant concerned the effect of time of weed emergence on maize and included the same maize growth stages as mentioned above. In both treatments, weed competition was compared to the control – the plot completely free from weeds, as well as to the plot fully covered with weeds. <em>Echinochloa crus-galli</em> in the amount of 20 plants per m<sup>2</sup>, which were not removed until the five-leaf stage or which emerged immediately after the seven-leaf stage of maize, did not show any competitive effect on the growth and development of maize. <em>Chenopodium album</em> was characterized by a similar effect at the same level of weed infestation severity and when not removed until the five-leaf stage as well as in the case of plants that emerged after the seven-leaf stage of maize. Both species present in an amount of 40 plants per m<sup>2</sup> needed to be removed no later than at the three-leaf stage of maize.

Natural revegetation of two block-cut mined peatlands in eastern Canada

1999 ◽  
Vol 77 (3) ◽  
pp. 447-459 ◽  
Author(s):  
Élisabeth Claire Robert ◽  
Line Rochefort ◽  
Michelle Garneau
Keyword(s):  
Vegetation Succession ◽  
Shrub Cover ◽  
Eastern Canada ◽  
Polytrichum Strictum ◽  
Sphagnum Fuscum ◽  
Natural Revegetation ◽  
Ericaceous Shrub ◽  
Eriophorum Spissum ◽  
Establishment Process ◽  
Sphagnum Magellanicum

Limited areas of post-mined peatlands are recolonized by Sphagnum-dominated communities. This study aims to recognize the spontaneous Sphagnum re-establishment process and to verify if Sphagnum directly colonizes the residual peat. Conditions favoring Sphagnum revegetation are suggested. Analyses of vegetation macrofossils of the newly formed peat allow the identification of colonizing species and vegetation succession profile. Botanical components of the pioneer horizon suggest that Sphagnum species can directly colonize the residual peat. When Polytrichum strictum (Kaulf.) Presl and Eriophorum spissum Fernald are present as early colonists, they are rapidly overgrown by Sphagnum species in the succession profile. Vegetation succession resulted mainly in the formation of hummocks and lawns dominated by Sphagnum fuscum (Schimp.) Klinggr., Sphagnum capillifolium (Ehrh.) Hedw., and Sphagnum magellanicum Brid., with a more or less dense ericaceous shrub cover. Floristic, hydrological, and chemical features indicate that a fibric peat accumulation ecosystem is progressively or partially restored.Key words: cut-over peatlands, restoration, Sphagnum, vegetation macrofossil, acrotelm.

Dust is the dominant source of “heavy metals” to peat moss (Sphagnum fuscum) in the bogs of the Athabasca Bituminous Sands region of northern Alberta

2016 ◽  
Vol 92-93 ◽  
pp. 494-506 ◽  
Author(s):  
William Shotyk ◽  
Beatriz Bicalho ◽  
Chad W. Cuss ◽  
M. John M. Duke ◽  
Tommy Noernberg ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Peat Moss ◽  
Dominant Source ◽  
Sphagnum Fuscum ◽  
Northern Alberta

A transplant experiment on the factors preventing lichen colonization of oak bark in southeast England under declining SO2 pollution

2003 ◽  
Vol 81 (5) ◽  
pp. 439-451 ◽  
Author(s):  
K Batty ◽  
J W Bates ◽  
J NB Bell
Keyword(s):  
Quercus Robur ◽  
Betula Pendula ◽  
Transplant Experiment ◽  
Pedunculate Oak ◽  
Visible Injury ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Bark Chemistry ◽  
So2 Pollution ◽  
Diffusion Tube

To investigate the factors responsible for limited lichen recolonization on oak with declining SO2 concentrations, Parmelia caperata (L.) Ach. and Parmelia saxatilis (L.) Ach. were transplanted to five stations along a transect running from central London (U.K.) into the surrounding countryside. Healthy thalli were transplanted onto young and mature Quercus robur L. (pedunculate oak) and Betula pendula Roth (silver birch), and some were moved with their original bark attached to investigate the importance of bark acidification. Relative growth rates and visible injury were monitored over 2 years, along with concentrations of atmospheric SO2 and NO2, measured using diffusion tube samplers and bark chemistry. SO2 concentrations were low in central London in comparison with the situation in previous decades, but they remain sufficiently high to harm the most sensitive lichens. NO2 concentrations increased sharply on approaching London, and levels were higher in winter than in summer. Bark pH was lower in mature oak than in birch or young oak at the two innermost stations, and levels of bark Mg also declined in London. Transplants of P. caperata survived on birch and young oak at all transect stations except Hyde Park, whereas P. saxatilis failed to grow over a wider range of the transect stations. We conclude that modest SO2 levels, interacting with low bark pH, still inhibit recolonization of oaks by P. caperata in central London. Parmelia saxatilis, in addition, appears to be limited by another factor such as the high NO2 concentrations that now characterize urban and suburban London, rather than through an inherently poor dispersal potential.Key words: atmospheric pollution, bark acidification, epiphytic lichens, NO2, recolonization, SO2.

scholarly journals Seed bank and growth comparisons of native (Virgilia divaricata) and invasive alien (Acacia mearnsii and A. melanoxylon) plants: implications for conservation

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5466 ◽  
Author(s):  
Stefan A. Goets ◽  
Tineke Kraaij ◽  
Keith M. Little
Keyword(s):  
Seed Bank ◽  
Growth Rates ◽  
Native Species ◽  
Soil Depth ◽  
Soil Seed Bank ◽  
Seed Banks ◽  
Acacia Mearnsii ◽  
Relative Growth ◽  
Sapling Growth ◽  
Study Species

Background Invasive alien plants with long-lived dormant seed banks and fast growth rates are difficult to manage. Acacia mearnsii and Acacia melanoxylon are two such invaders in the southern Cape of South Africa which occasionally co-occur with a native, ecologically analogous species, Virgilia divaricata. We compared the performance of these three species to determine potential for the native species to be used in management of the invasives. Methods We compared the study species in terms of (i) soil seed bank densities, their vertical distribution, and the viability of seeds underneath the canopies of mature trees; (ii) seedling growth from planted seeds over a period of three months; and (iii) growth rates of saplings over a period of 10 months in stands that have naturally regenerated in the field (these stands were dominated by A. mearnsii) and where saplings have been exposed to varying levels of competition from surrounding saplings. Results Seed bank densities differed significantly among species but not among soil depth classes. Acacia mearnsii had the highest seed bank densities (mean of 7,596 seeds m−2), followed by V. divaricata (938 seeds m−2) and A. melanoxylon (274 seeds m−2). Seed viability was high (87–91%) in all three study species and did not differ significantly among species or soil depth classes. As seedlings, V. divaricata significantly outgrew A. mearnsii in terms of height, root and shoot dry mass, and root:shoot ratio. Relative growth (the relationship between growth in height and initial height) was negative in the seedlings of both species. Trends during the sapling stage were opposite to those during the seedling stage; A. mearnsii (but not A. melanoxylon) saplings significantly outgrew V. divaricata saplings in height, while relative growth rates were positive in all species. Sapling growth of all species was furthermore uninfluenced by the collective biomass of surrounding competitors. Discussion Our findings suggest that amongst the measures considered, A. mearnsii’s success as an invader is primarily attributable to its large seed banks, and secondly to its vigorous growth in height as saplings. However, the superior growth performance of V. divaricata seedlings and no apparent negative effect of competition from the acacias on sapling growth show promise for its use in integrated management of the acacias.

Competitive ability of cowpea genotypes with different growth habit

Weed Science ◽  
2006 ◽  
Vol 54 (4) ◽  
pp. 775-782 ◽  
Author(s):  
Guangyao Wang ◽  
Milton E. McGiffen ◽  
Jeff D. Ehlers ◽  
Edilene C. S. Marchi
Keyword(s):  
Growth Rate ◽  
Competitive Ability ◽  
Growth Habit ◽  
Biomass Accumulation ◽  
Growing Season ◽  
Similar Reduction ◽  
Relative Growth ◽  
Use Efficiency ◽  
Common Purslane ◽  
Prostrate Growth

Growth habit is an important determinant of competitive ability in legume crops. Erect ‘Iron-Clay’ (IC), semi-erect ‘IT89KD-288’ (288), and prostrate ‘UCR 779’ (779) cowpea genotypes were planted with four densities of common sunflower or common purslane to determine which cowpea growth habit is more competitive to these weeds having markedly different statures. Both sunflower and purslane reduced cowpea relative growth rate (RGR) but at different phases of the growing season. Low-growing purslane had an effect in the earlier part of the season, and sunflower decreased cowpea RGR in the middle of growing season. RGR of genotype IC was the least affected and genotype 779 the most reduced by sunflower. Cowpea apparently compensated for early season purslane competition by increasing RGR after purslane flowering, with RGR for the IC genotype increasing the most and 779 increasing the least. All cowpea genotypes caused a similar reduction in sunflower biomass accumulation; but purslane biomass was most reduced by genotype IC and least affected by genotype 288. Erect genotype IC is more competitive due to its taller stature, greater height growth rate, and higher position of maximal leaf area density, despite a lower photosynthetic rate and light use efficiency than the other cowpea genotypes. Our results suggest that erect cowpea growth habit may be generally more competitive with weeds compared to semi-erect or prostrate growth habit.

Relative Growth of Themeda Australis and Poa Labillardieri in Pots in Response to Phosphorus and Nitrogen.

1973 ◽  
Vol 21 (1) ◽  
pp. 1 ◽  
Author(s):  
RH Groves ◽  
K Keraitis ◽  
cWE Moore ◽  
HJ Langer
Keyword(s):  
Shoot Growth ◽  
New South ◽  
Statistical Treatment ◽  
Dry Weight ◽  
Competitive Effect ◽  
Relative Growth ◽  
Shoot Dry Weight ◽  
South Wales ◽  
Shoot Weight ◽  
Nitrogen Contents

Results are presented of a pot experiment on the responses of Themeda australis and Poa labillardieri to increasing levels of substrate phosphorus and nitrogen. The species were grown either alone or together. When grown alone both species responded to increasing phosphorus and nitrogen and there was a significant interaction between the two elements in shoot growth per half-pot. There was no effect of increasing phosphorus without added nitrogen and no effect of increasing nitrogen without added phosphorus. At intermediate and high levels of substrate phosphorus there was a significant competitive effect between the shoot weight per half-pot and the tiller number of Themeda and Poa plants when grown together, irrespective of the nitrogen level. Poa always had a greater shoot dry weight and more tillers when grown with Themeda than when grown alone, and conversely Themeda a lower shoot dry weight and less tillers when grown with Poa than when grown alone. Chemical analyses of 22-week-old plant tissue showed that in Poa plants grown with Themeda the phosphorus and nitrogen contents were significantly greater than in Poa plants grown alone, at both intermediate and high levels of substrate phosphorus. The enhanced ability of Poa plants to absorb nutrients and grow in response to a low level of added phosphorus at the expense of Themeda plants when the two species are mixed in pots is similar to their response in the field in southern New South Wales. A description of the statistical treatment of the results, especially the competitive effect between Themeda and Poa when grown together, is appended.

Absence of Differential Fitness Between Giant Foxtail (Setaria faberi) Accessions Resistant and Susceptible to Acetyl-Coenzyme A Carboxylase Inhibitors

Weed Science ◽  
1996 ◽  
Vol 44 (1) ◽  
pp. 18-24 ◽  
Author(s):  
Ronald J. Wiederholt ◽  
David E. Stoltenberg
Keyword(s):  
Growth Rate ◽  
Leaf Area ◽  
Relative Growth Rate ◽  
Seed Yield ◽  
Competitive Ability ◽  
Acetyl Coenzyme A ◽  
Relative Growth ◽  
Giant Foxtail ◽  
Dry Biomass ◽  
Acetyl Coenzyme A Carboxylase

Experiments were conducted to determine the productivity, inter-, and intraspecific competitive ability of giant foxtail accessions resistant (PCW1) and susceptible (AC1) to acetyl-coenzyme A carboxylase (ACCase) inhibitors. Under noncompetitive conditions in the field, shoot dry biomass, plant height, and leaf area over time were similar between the PCW1 and AC1 accessions. The instantaneous relative growth rate and instantaneous net assimilation rate did not differ between the accessions; however, the instantaneous leaf area ratio was slightly greater for the AC1 accession than the PCW1 accession. The seed yield was similar between the PCW1 and AC1 accessions. Addition series experiments were conducted in the field to determine the intraspecific competitive ability of the PCW1 and AC1 accessions. Regression surface analysis of reciprocal mean shoot dry biomass and seed yield indicated that the relative competitive ability of the PCW1 and AC1 accessions was similar. Replacement series experiments were conducted in the greenhouse with or without corn to determine the interspecific competitive ability of the accessions. The relative growth rate, shoot dry biomass, and seed yield of the PCW1 and AC1 accessions were greater without than with corn competition. The relative competitive ability of the PCW1 and AC1 accessions was similar with or without corn competition based on shoot dry biomass or seed yield. These results indicated that the intra- and interspecific competitive ability of the PCW1 and AC1 giant foxtail accessions are similar and suggest that resistance to ACCase inhibitors has not reduced the relative fitness of the PCW1 accession.

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