Abundance Of Mosses Research Articles

Vertebrate herbivores and ecosystem control: cascading effects of faeces on tundra ecosystems

We tested the hypothesis that large herbivores manipulate their own food supply by modifying soil nutrient availability. This was investigated experimentally the impact of faeces on grasses, mosses and soil biological properties in tundra ecosystems. For this, we increased the density of reindeer Rangifer tarandus platyrhynchus faeces and studied the response of a tundra system on Spitsbergen to this single faecal addition treatment for four subsequent years. From the third year onwards faecal addition had unambiguously enhanced the standing crop of grasses, as evidenced by an increase in both shoot density and mass per shoot. Although reindeer grazing across experimental plots was positively related to the abundance of grasses in anyone year, the increase in grass abundance in fouled plots failed to result in greater grazing pressure in those plots. Faecal addition enhanced soil microbial biomass C and N, particularly under wet conditions where faecal decay rates were greatest, whilst grasses appeared to benefit from faeces under dry conditions. Whilst growth of grasses and soil microbial biomass were stimulated by faecal addition, the depth of the extensive moss layer that is typical of tundra ecosystems was significantly reduced in fouled plots four years after faecal addition. The greatest reduction in moss depth occurred where fouling increased soil microbial biomass most, suggesting that enhanced decomposition of moss by a more abundant microbial community may have caused the reduced moss layer depth in fouled plots. Our field experiment demonstrates that by the production of faeces alone, vertebrate herbivores greatly impact on both above‐ and belowground components of tundra ecosystems and in doing so manipulate their own food supply. Our findings verify the assertion that grazing is of fundamental importance to tundra ecosystem productivity, and support the hypothesis that herbivory is instrumental in promoting grasses whilst suppressing mosses. The widely observed inverse relationship between grass and moss abundance in the field may therefore reflect the long history of plant‐herbivore interactions in tundra ecosystems.

The moss flora of Gebel St. Katherine area (Sinai) with nine new records

Sixteen moss species representing eleven genera, six families and five orders are reported from Gebel St.Katherine area including nine new records. Mosses known from this area amount to 28 taxa. Diagnostic features,notes on morphology-habitat relations and moss abundance of the 16 taxa are provided and a key for theidentification of the mosses known at present from the study area based on gametophytic characters isconstructed.

Arctic changes

Whether at the molecular or the population level, it is important to determine how environmental changes affect plants. The Arctic and subarctic regions present an especially interesting place to examine plant ecology because the conditions are extreme and the environment is fluctuating. Reported ozone depletion, oceanic pollution and increased temperatures probably will have an effect on Arctic plants in the future. But the question remains: how do environmental changes in the Arctic affect plants and their abundance? Enrico Graglia 1 Graglia E. et al. Effect of environmental perturbations on abundance of subarctic plants after three, seven, and ten years of treatments. Ecography. 2001; 24: 5-12 Crossref Scopus (88) Google Scholar and colleagues now reveal results from a ten-year study that shows that short-term changes to the Arctic environment can alter the plant community in a long-lasting manner and even at accelerated rates over a long period of time. Previously, researchers considered Arctic biomass to be under the influence of temperature and nutrient availability in an environment of low competition. Graglia et al. tested this hypothesis by the addition of nutrients, temperature and shading in subarctic natural habitats and subsequently determining alterations in plant abundance after three, seven and ten years of treatments. The group found that among the vascular plants, grasses responded the most strongly to treatments. Nutrient addition of nitrogen:phosphorus:potassium mixtures had the dominant effect, wheres the effect of warming and shading was smaller. Grasses increased with more nutrient availability whereas cryptogams decreased with the addition of fertilizer and an increase in temperature. The decreased abundance of mosses and lichens in nutrient enriched soils is because of increased competition from grasses. Habitat warming at the coldest spots of the experiment increased deciduous shrubs. The most surprising result from the study is that the transient treatments led to long-term effects over the ten-year study. The authors noted cumulative effects from the various treatments, synergy between different treatments, and stability of the responses during the ten years of treatments. The authors warn that once a community modifies its composition, the changes will continue at a stable or accelerated rate for long time periods. It will be valuable to know how the effects on abundance relate to total plant biomass, and how current changes of the environment alter the plant makeup in the Arctic.

Effects of environmental perturbations on abundance of subarctic plants after three, seven and ten years of treatments

Analyses of changes in vegetation were carried out after three, seven and ten years of fertilizer addition, warming and light attenuation in two subarctic, alpine dwarf shrub heaths. One site was just above the tree line, at ca 450 m a.s.l., and the other at a much colder fell‐field at ca 1150 m altitude. The aim was to investigate how the treatments affected the abundance of different species and growth forms over time, including examinations of transient changes. Grasses, which increased in abundance by fertilizer addition, and cryptogams, which, by contrast, decreased by fertilizer addition and warming, were the most sensitive functional groups to the treatments at both sites. Nutrient addition exerted a stronger and more consistent effect than both shading and warming. Warming at the fell‐field had slightly greater effect than at the warmer tree line with an increase in deciduous shrubs. The decreased abundance of mosses and lichens to fertilizer addition and/or warming was most likely an indirect treatment effect, caused by competition through increased abundance and overgrowth of grasses. Such changes in species composition are likely to alter decomposition rates and the water and energy exchange at the soil surface. We observed few, if any, transient effects of declining responses during the 10 yr of treatments. Instead, there were many cumulative effects of the treatments for all functional groups and many interactions between time and treatment, suggesting that once a change in community composition is triggered, it will continue with unchanged or accelerated rate for a long period of time.

Molecular organic geochemical peculiarities of lacustrine core sediments in Fildes Peninsula, King George Island, Antarctica

The peculiarities of lipids in lacustrine core sediments from Fildes Peninsula, King George Island, Antarctica, are reported. The origin of high-molecular-weight n-alkanes, alkenes, fatty acids, alcohols Is supposed to be related to the abundant moss occurring in the sediments. Abundantiso- andanteiso-fatty acids that occur in the sediments indicate a relatively strong bacterial activity in non-ice-cover zone than in other regions in Antarctica. The C18:2 unsaturated fatty acids mainly originate from autochthonous algae in the sediment pool, and the C18:2C18:0 ratios in the profile are controlled more by paleotemperatures than source assemblies. Long-chain alkenones were identified in freshwater lacustrine sediment in Antarctica for the first time, of whichPrymnesiophyceae is assumed to be the source organism. High relative abundance of C37:4 homologue in long-chain alkenone well correlates to the severely cold climate in Antarctica.

Survival and growth of transplantedFontinalis dalecarlica (Bryophyta) in controlled flow and short-term regulated flow sites in the Perhonjoki River, Western Finland

Impoundment, channelisation and short-term regulation of the Perhonjoki river have caused changes in the distribution and abundance of aquatic mosses. While some moss species have colonised the beds in the channelised and short-term regulated part of the river, Fontinalis spp. are mainly restricted to the sites above the power plant where flow variability is low. Therefore, as a first step towards gaining a better understanding of the factors contributing to the distribution and abundance of Fontinalis dalecarlica (Bruch & Schimp, Fontinalaceae) in the Perhonjoki, a transplant experiment was conducted to test whether short-term flow regulation restricts the survival and growth of this species. Artificial substrates with tufts of F. dalecarlica were transplanted in July 1993 to controlled flow and short-term regulated flow riffles, above and below the Kaitfors power plant, respectively. Survival and growth were monitored for 1 year. F. dalecarlica survived the winter and grew well during the summer in the short-term regulated flow site. Mosses did not grow at the controlled flow site. Effects of channelisation are partly seen in the fate of the substrates. At the controlled flow site, ten of the 30 substrates were lost during the winter, and 67% of the substrates in the mid-channel sub-area and 40% of the substrates in the sub-area near the bank had suffered severely during this experiment. At the short-term regulated flow site, the equivalent percentages were 17, 13 and 27%, respectively. Hygrohypnum spp. attached to the substrates during the summer of 1994. The results indicate that short-term regulation does not prevent the survival and growth of F. dalecarlica and thus does not prevent this species from surviving in the areas below the power plant. Present environmental conditions seem to contribute to the poor colonising capability of this species and thus limit colonisation. However, we suggest that the recovery of F. dalecarlica could be enhanced by moss transplant. Copyright © 1999 John Wiley & Sons, Ltd.

Rare Plant Abundance in an Endangered Species "Hot Spot"

In 1996, we measured the abundance and distribution of two of the six rare plant species growing within an endangered species hot spot in the Ninigret National Wildlife Refuge in southern Rhode Island. Mean densities and total popula? tion estimates of Aletris farinosa (18.0 plants/m2; 41,400 individuals) and Platanthera ciliaris (10.7 plants/m2; 24,610 individuals) were extremely high within the 2300 m2 core of the hot spot, yet fewer than 40 stems of both species combined were found outside the core. Data on soil moisture, organic matter, and texture, along with abundance of Drosera, lichens, mosses, and unvegetated ground provided insights into the distribution of A. farinosa and P. ciliaris. The fact that there appear to be more individuals of P. ciliaris at this single location than in all of the rest of New England underscores the importance of this site.

Temperature and Plant Species Control Over Litter Decomposition in Alaskan Tundra

I compared effects of increased temperature and litter from different Alaskan tundra plant species on cycling of carbon and nitrogen through litter and soil in microcosms. Warming between 4° and 10°C significantly increased rates of soil and litter respiration, litter decomposition, litter nitrogen release, and soil net nitrogen mineralization. Thus, future warming will directly increase rates of carbon and nitrogen cycling through litter and soil in tundra. In addition, differences among species' litter in rates of decomposition, N release, and effects on soil net nitrogen mineralization were sometimes larger than differences between the two temperature treatments within a species. Thus, changes in plant community structure and composition associated with future warming will have important consequences for how elements cycle through litter and soil in tundra. In general, species within a growth form (graminoids, evergreen shrubs, deciduous shrubs, and mosses) were more similar in their effects on decomposition than were species belonging to different growth forms, with graminoid litter having the fastest rate and litter of deciduous shrubs and mosses having the slowest rates. Differences in rates of litter decomposition were more related to carbon quality than to nitrogen concentration. Increased abundance of deciduous shrubs with future climate warming will promote carbon storage, because of their relatively large allocation to woody stems that decompose slowly. Changes in moss abundance will also have important consequences for future carbon and nitrogen cycling, since moss litter is extremely recalcitrant and has a low potential to immobilize nitrogen.

Habitat Correlates of the Southern Torrent Salamander, Rhyacotriton variegatus (Caudata: Rhyacotritonidae), in Northwestern California

Asystematic stratified sampling design was used to quantify the habitat relationships of the southern torrent salamander, Rhyacotriton variegatus, in northwestern California. We sampled 53 first to third order streams, each surrounded by at least 5-7 ha of relatively homogeneous forest or harvested forest habitat. Measurements of 121 attributes of the forest and stream environment were recorded in conjunction with area-constrained aquatic sampling for salamanders. A subset of 68 variables, grouped into 11 ecological components including attributes at the landscape, macrohabitat, and microhabitat scales, was used in a hierarchical analysis of habitat associations. Results from discriminant and regression analyses indicated that this species occurs within a relatively narrow range of physical and microclimatic conditions and is associated with cold, clear headwater to low-order streams with loose, coarse substrates (low sedimentation), in humid forest habitats with large conifers, abundant moss, and HO% canopy closure. Thus, the southern torrent salamander demonstrates an ecological dependence on conditions of microcli- mate and habitat structure that are typically best created, stabilized, and maintained within late seral forests in northwestern California.

Riparian Bryophytes of the H. J. Andrews Experimental Forest in the Western Cascades, Oregon

The knowledge of the distribution and habitat demands for bryophytes in the Pacific Northwest is scarce, and few published quantitative accounts of the flora are present. The present paper includes habitat description, elevational range, substrate preference, and frequency estimates for more than 130 riparian mosses and liverworts found in old-growth Pseudotsuga-Tsuga forests of the H. J. Andrews Experimental Forest, Oregon. The data are based on 360 samples distributed among 42 sites covering 1st to 5th order streams and 420 to 1250 m. TWINSPAN analysis resulted in 6 sample groups, representing samples from different elevations, geomorphic surfaces, and stream sizes. The most common mosses are Eurhynchium oreganum, Isothecium stoloniferum, Hypnum circinale, and Dicranum fuscescens. Among the hepatics Scapania bolanderi, Cephalozia lunulifolia, and Porella navicularis are the most abundant species. Most species are rare at both site and sample plot level, and this is especially true for acrocarps where more than one-third of the observed species occurred in only one or two sites or/and samples. Four of the occurring species (i.e., Antitrichia curtipendula, Buxbaumia piperi, Douinia ovata, and Ptilidium californicum) are listed for special management and/or regional surveys. Bryophytes constitute an important and conspicuous component of old-growth forests in the Pacific Northwest (Lesica et al. 1991; McCune 1993; Schofield 1988); however, few studies on the abundance and distribution of mosses and liverworts have been conducted. The epiphytic flora, composed of bryophytes and lichens, of old-growth Douglas-fir has been shown to be species rich and influences nutrient dynamics and overall production in old-growth stands (Pike et al. 1975, 1977). Besides these studies, however, there has been until now no published account of factors influencing the distribution of individual species within old-growth forests (see however Peck et al. 1995; Schofield 1976). Dispite this lack of study, many bryophytes are considered to be dependent of old-growth conditions (FEMAT 1993; Soderstrom 1988). Thus, effective management of the bryophyte flora, which is an important forest product of the region (Peck 1990; Schlosser et al. 1992) and a significant part of forest biodiversity, is constrained by lack of knowledge. Riparian zones are thought of as key elements in the forested landscape, and preservation of these is a major goal of forest management (FEMAT 1993). Of the mosses and liverworts considered as vulnerable in the Pacific Northwest (USDA 1994), many occur in riparian areas. This association is dependent on many factors, but the occurrence of a wide range of different substrates, disturbance patterns, and a moist microclimate are important contributors to the diversity in these zones (Glime & Vitt 1987; Vitt et al. 1986). The present paper reports habitats and frequencies of species found in riparian areas of old-growth Pseudotsuga-Tsuga forests in the western Cascades of Oregon. A general treatment of the bryophyte community patterns will be published elsewhere.

Vegetation changes following human disturbance of mid-montane forest in the Wau area, Papua New Guinea

ABSTRACTThis paper examines the floristic changes that occur following human disturbance in mid-montane forest in the Wau area in Papua New Guinea. The study was restricted to a 1600–2400 m altitudinal range on Mt Kaindi, with disturbed forest, and Mt Missim, with undisturbed forest. Special attention was given to the status ofNothofagus pulleiwhich is locally dominant on Mt Kaindi.A major change in floristic composition was observed between 1800 and 2000 m. The abundance and species composition of ferns and mosses above 2000 m characterizes the floristic differences.Nothofagus pulleiwas found to be a pioneer species with a long life-span, one which does not regenerate under its own cover. There were no other important floristic differences betweenNotho-fagus-dominated forest and mixed mid-montane forest.Nothofagus pulleilocally dominates the canopy and thereby suppresses the growth of other trees.

Extreme southern locations for moss sporophytes in Antarctica

Abundant immature sporophytes of the moss Pottia heimii are reported from the Lower Taylor Valley, McMurdo Dry Valleys and from Cape Chocolate, Victoria Land. These finds extend the reported southern limit for the occurrence of abundant moss sporophytes to 77° 55′S.

The Ecological Changes of Breckland Grass Heaths and the Consequences of Management

1. Sites of previous vegetation quadrats were revisited and reanalysed. There was a trend from characteristic Breckland communities with an abundance of lichens, winter annuals and cushion-forming mosses towards rank grassland. 2. A survey of Breckland grass heaths showed that the characteristic plant communities were found on rabbit-grazed but not sheep-grazed sites. 3. Sites which had been rotovated had shorter grass, a higher abundance of lichens and annual plants, less organic matter and greater rabbit activity than control plots. 4. Encouraging rabbits and disturbing the soil are essential to maintain these heaths.

Variations de la régénération préétablie dans les sapinières boréales en fonction de leurs caractéristiques écologiques

The renewal of boreal fir stands after harvesting is related to the abundance of fir advanced regeneration. The objective of this study was to compare the advanced regeneration in 45-years-old balsam fir stands of second growth to determine if ecological site conditions could explain some regeneration problems noted in the balsam fir – white birch ecoclimatic domain. Seven ecological phases were studied; these are among the most common in the Laurentians north of Québec. On the basis of fir seedling densities (2 years old and more), three groups could be distinguished using a cluster analysis method for grouping means. Dry balsam fir – herb-and-moss type on well drained tills formed a first group characterized with very high seedling densities (> 60 000 seedlings/ha). A second group, characterized with high seedling densities (25 000 – 40 000 seedlings/ha), was constituted of three phases with an important moss cover:the mesic balsam fir – moss-and-herb type on moderately well drained tills, the humid balsam fir – moss-and-herb type on imperfectly drained tills with seepage, and the humid balsam fir – moss type on imperfectly drained tills. A third group, with low seedling densities (< 15 000 seedlings/ha), included three phases recognized by their important herb cover associated with a less abundant moss cover: the dry balsam fir – herb type on well drained till, the mesic balsam fir – white birch – herb type on moderately well drained till, and the mesic rich balsam fir – herb type on moderately well drained tills with seepage. Low densities of fir advanced regeneration seemed to be related to the abundance of leaf litter on the forest floor that could hinder fir regeneration. Insufficient natural coniferous regeneration can be anticipated in this last group if harvesting follows the 45-year rotation currently used now in Quebec.

Ecologie et évolution des jardins de fourmis en Guyane Française

Ant gardens were followed intermittently, from 1986 to 1989, in a Citrus grandis plantation and in a lowland rain forest, at the Piste de St Elie study site, French Guiana. This plant-ant asociation most likely originates in a different way in open and closed environments. Whereas the plant partner settles first on a tree in a plantation, the ants secondarily entering the root-ball to build their nest, the ant partner is the first settler on rainf orest trees, epiphytes later establishing themselves on their nests. The number of plant partners in an ant garden ranged from 1 to 5 species in the hundreds of gardens studied. They belonged mostly to a limited number of epiphytic families : Araceae, Bromeliaceae, Gesneriaceae, and Peperomiaceae. The ant partners were less numerous in species (1 to 3), belonging to genera Camponotus and Crematogaster. Ant gardens in tree plantations, forest edges, or river sides were composed of more plant species than those found in rain forests. The number of plant partners also increased with the size and age of the ant garden. No specific plant-ant association was ever found in the ant gardens examined. When Anthurium gracile was the only plant partner, there was also a single ant associate, but it was seldom the same, strongly suggesting that the association is initiated at random. In 50 % of the ant gardens studied, whatever the environment, there were two different ant partners per garden. Seven categories of plant-ant associations were recognized. A single tree could harbour as many as 10 ant gardens of different composition. The growth of a new aggregation of ant gardens was studied from 1986 to 1989 in a Citrus plantation, after destruction of all pre-existing associations. The establishment of new ant-gardens was very rapid, and took place within a single year. The major factors influencing their establishment were a sufficient amount of light, and the structure of the bark of the supporting tree. Too much shade and an abundance of epiphytic moss were obviously unsuitable conditions. In the Citrus plantation, ant gardens increased more rapidly in numbers and size on the trees grown on well drained soils ; conversely, they were less abundant on stunted, moss covered, trees planted in hydromorphic soils. Under favourable conditions, the number of ant gardens in Citrus plantations can become impressive : 1015 were enumerated on 456 trees in 1989, three years after complete clearance of all previous gardens ! Both plants and ants take advantage of their association in an ant garden. The plant partner benefits from the nutrients provided by the humus of the root-ball and the decomposing detritus of the ant nest. They also take advantage of the active protection afforded by their aggressive ant partners. Their seeds may also be dispersed by the ants within and around the garden. The ants also greatly benefit throughout the year from the secretions of the floral and extra-floral nectaries of their plant associates, and from the pulp of their fleshy fruits. The intricate root system of the epiphytes also provides shelter and reinf orcement to the brood chambers. An ant garden largely functions in isolation. Contrary to most true myrme-cophytes still deriving most of their necessary nutrients from the soil, ant associated epiphytes no longer depend on the soil substrate. All the necessary nutrients are provided by the enriched humus surrounding the arboreal ant nest(s).

The Habitat and Distribution of Meesia triquetra in North America and Greenland

Meesia triquetra (Richt.) Aongstr. occurs in rich fens having surface waters with high pH and calcium concentrations. The present day distribution of M. triquetra in North America and Greenland is documented from Alaska and British Columbia east to Newfoundland and Ellesmere Island, N. W. T., and south to northern California in the west and Pennsylvania in the east. A large number of collections have been madefrom the mountains andfoothills in Alaska, British Columbia, and Alberta; also notable are the many collections from the Great Lakes area. All Quaternary subfossil records lie in the same geographic area as extant records except for one station in Iowa and another in southern Ohio, both of which lie south of the present-day range. Meesia triquetra (Richt.) Aongstr. can be distinguished from the other two North American species of Meesia by a distinct three-ranked leaf arrangement, acute leaf apices, denticulate leaf margins, and dioicous sexual condition. Meesia triquetra is a rich fen indicator species of high fidelity. In the boreal region it grows in carpets in open mires, including the flarks of patterned fens and floating mats of pond margins. Meesia triquetra can also be found in hollows of alkaline, swampy Betula and Salix woods. In the Arctic, M. triquetra grows on calcareous seepage slopes and at the bases of hummocks in wet meadows. This moss is considered uncommon and strictly limited in its distribution by habitat availability (Odgaard 1988; Slack et al. 1980). I had opportunity to outline the habitat and distribution of this rare indicator species in North America as part of a larger work on the population biology of M. triquetra. Meesia triquetra usually occurs in fens with high species richness. Among the most abundant moss species found in these fens are Aulacomnium palustre (Hedw.) Schwaegr., Bryum pseudotriquetrum (Hedw.) G.M.S., Drepanocladus revolvens (Sw.) Warnst., D. vernicosus (Mitt.) Warnst., and Tomenthypnum nitens (Hedw.) Loeske. It has also been found as isolated plants in carpets, below lawns of Sphagnum angustifolium (Russ.) C. Jens. and hummocks of S. magellanicum Brid., although this assemblage is rare. When present, M. triquetra can be abundant but is usually found as stems intermingled in carpets of Drepanocladus revolvens (Sw.) Warnst. and Scorpidium scorpioides (Hedw.) Limpr. Other indicator species of these mires are Calliergon triTABLE 1. Chemical parameters of surface waters from fens in which Meesia triquetra occurs.

Population Dynamics of Rosebay Rhododendron Thickets in the Southern Appalachians

PLOCHER, A. E. AND K. L. CARVELL (Div. For., West Virginia Univ., Morgantown, WV 26506-6125). Population dynamics of rosebay rhododendron thickets in the southern Appalachians. Bull. Torrey Bot. Club 114:121-126.-Seven north-central West Virginia Rhododendron maximum thickets, ranging from 0.2 to 0.6 ha, were studied to determine: the occurrence of and ecological conditions for rhododendron reproduction and vegetative propagation, the relationship between past logging history and thicket formation and dynamics and the effect of dense rhododendron thickets on overstory reproduction and recruitment. Thickets were relatively even-aged and did not appear to be increasing in area. The overstories were younger than the rhododendrons and tree seedlings and saplings occurred within thickets. Thickets were found to date from the most recent logging operations. Moisture conditions varied from mesic to subxeric. Drier thickets with more open canopies, sparse herb coverage and an abundance of moss produced rosebay seedlings prolifically in adjacent areas. Thickets with wetter conditions, denser canopies and lush herbaceous growth produced very few rosebay seedlings; however, they exhibited profuse layering.

OCCURRENCE OF PHYLLOTRETA STRIOLATA, THE STRIPED FLEA BEETLE, IN OPEN PRAIRIE, FOREST, AND PARKLAND OF SASKATCHEWAN (COLEOPTERA: CHRYSOMELIDAE)

AbstractIn Saskatchewan the range of Phyllotreta striolata (F.), a pest of parkland rapeseed crops, includes the open prairie in the southwest and the boreal forest in the north. The population of P. striolata on the open prairie is small, with cruciferous weeds being the major host plants. Cruciferous crops grown on the open prairie will almost certainly attract some P. striolata. The population of P. striolata in the forest is substantial, and the range extends northward into arctic regions. Although adults of P. striolata feed upon cruciferous plants growing in the forest, these plants do not appear abundant enough to constitute an adequate food supply. In addition, the identity of the major host plants of the larvae in the forest is unknown. In laboratory experiments, adults of P. striolata were attracted to and attempted to feed upon seven species of forest mosses; however, attempts to maintain a laboratory colony of P. striolata on one of the more abundant mosses were unsuccessful. Forest inhabiting P. striolata attacked rape planted in forest clearings, and therefore probably would infest rape crops grown along the forest edge or in newly cleared areas.

Identification, abundance, and origin of moss, liverwort, and algal contaminants in greenhouses of containerized forest nurseries

Five containerized forest nurseries in British Columbia were surveyed for cryptogam (moss, liverwort, and algal) contamination. Fourteen cryptogam species (five bryophyte and nine algal species) were identified from contaminated styroblock containers. No cryptogams were cultured from the peat and soil mix samples and no mosses or liverworts were detected in the water samples. Algae were found in water samples of two of the five nurseries, but only one of these had species similar to those contaminating the styroblocks. Air samples contained moss, liverwort, and six of the nine algal contaminant species. The relative abundance and distribution of cryptogams at each nursery is given and data are presented which indicate an airborne mode of contamination. The results are discussed with respect to the nature of the contamination and possible control of cryptogam pests in greenhouses of containerized forest nurseries.

LATE DEVENSIAN DEPOSITS FROM KILDALE, NORTH-EAST YORKSHIRE

SUMMARY A Late Devensian deposit containing abundant moss remains is described. One species assumes significance because of its first recorded occurrence in British late-glacial sediments. A radiocarbon date of c . 16,000 BP obtained from an accumulation of the earliest deposited moss fragments assists in the interpretation of the Devensian deglaciation sequence in the region. This is considered to have been accomplished between about 18,000 and 16,000 BP probably initially by the separation and stagnation of ice lobes in valleys.