Moss Mats Research Articles

Monitoring of pollen rain in moss polsters and mats in view of their suitability as controls for determining the air-borne component of pollen spectra in herbivore faeces

Pollen has been extracted from six bryophyte and two lichen taxa, sampled from three habitats: upland heath, lowland bog and mixed woodland, in both west and east Scotland. The highest number of pollen taxa was recorded in bothSphagnum andThuidium; the lowest numbers of pollen taxa were recorded in two of the mosses and both lichens. For pollen rain control purposes in herbivore faecal studies, woodland species of bryophytes are not suitable due to the sheltering effects from rain provided by the overhead canopy. Open habitats such as moorland heath and bog provide polsters/mats which normally trap pollen rain more effectively for control purposes. The aim of this study was twofold: to observe the effectiveness of selected polsters and lichens as traps for pollen rain and to establish eventually, whether or not such vegetative traps could be used as controls in pollen spectra analyses of herbivore faeces for the determination of nutritional regime and habitat. From a comparison with recent studies in north west Spain of three taxa in common with Scottish samples,Polytrichum demonstrated a consistently higher number of pollen taxa trapped.Thuidium andCladonia all yielded between one and a half and three times the number of pollen taxa as in the same three bryophyte/lichen taxa sampled in Scotland. Investigation relating the pollen rain trapped in polsters to that in faecal material are continuing, and will be reported in due course.

Monitoring of pollen rain in moss polsters and mats in view of their suitability as controls for determining the air-borne component of pollen spectra in herbivore faeces

Monitoring of pollen rain in moss polsters and mats in view of their suitability as controls for determining the air-borne component of pollen spectra in herbivore faeces

Branch Epiphyte Assemblages in the Forest Interior and on the Clearcut Edge of a 700-Year-Old Douglas Fir Canopy in Western Oregon

Branch Epiphyte Assemblages in the Forest Interior and on the Clearcut Edge of a 700-Year-Old Douglas Fir Canopy in Western Oregon

Mosses and the production of Chinese gallnuts

Chinese gallnuts are galls that form on tfie-leaves of sumac trees (Rhus spp) in response to attack by aphids in the Eriosomatinae, for which mosses form obligate winter hosts. Walls of the gallnuts may comprise up to 70% tannins and yield compounds of considerable commercial value, notably tannic acid and gallic acid. Gallnut production can therefore have a major impact on the local economy in rural areas of China.At least 14 types of gallnut have been described, each caused by a different species of aphid. A wide range of mosses act as winter hosts. Of greatest importance commercially is the true-horned gallnut which forms on R. chinensis in response to attack by Schlechtendalia chinensis, an aphid that overwinters on members of the Mniaceae, particularly Plagiomnium acutum. There are six generations of S. chinensis in each annual cycle. Reproduction is principally viviparous and parthenogenetic, except for a single sexual generation produced after spring migrants fly from mosses to the sumac trees in April and early May.True-horned gallnuts are traditionally harvested from semi-natural woodland on rocky hillsides. Approximately 1-2% cover of P. acutum is adequate to give high production of gallnuts provided that it is uniformly distributed, and favourable distribution and abundance of the moss is achieved by artificial transplantation. Attempts are being made to produce gallnuts by growing sumac trees in agricultural fields, but success is lirnited by the difficulty of establishing Plagiomnium spp in the fields. One solution is to cultivate the moss in plastic bowls which are kept for most of the year in sheds. In October each year the bowls are placed outside under the sumac trees for several weeks and autumnmigrant aphids fly into the moss colonies. The bowls are kept in the shed during the winter, the moss mat is stripped from the bowls and placed under the trees in April, and spring-migrant aphids then leave the moss and fly to the trees. The moss regenerates in the bowls during the summer. We are investigating the growth and reproductive ecology of P. acutum as an approach towards increasing gallnut production.

Positive Plant Interactions in Tundra Vegetation and the Importance of Shelter

(1) The hypothesis that positive plant interactions, arising from species aggregations, are important in harsh environments was tested on the sedge Carex bigelowii in the alpine/subarctic tundra of Swedish Lapland. (2) Association analyses showed that, in contrast to records for the High Arctic, aggregations of the low-growing species ( 2 cm away from the dwarf shrubs or outside the moss mat. (3) The effect of the dwarf shrubs was interpreted as a result of above-ground shelter because shoot height, as well as number of shoots, also increased when plywood shelters were erected on the windward side of C. bigelowii. The effects of this above-ground shelter on shoot growth could result from increased snow cover, protection against strong desiccating winds early in the growing season, and a warmer micro-climate. (4) An alternative explanation for the increased growth of C. bigelowii growing near other species is that their patchy distributions, particularly those of the dwarf shrubs, may be related to localized increased soil nutrient status. When fertilizer was added to C. bigelowii, there were significant increases in shoot height and number. The benefits to the growth of C. bigelowii when growing close to other species may be a combination of shelter effects and a patchy distribution of nutrients.

Hydrologic and thermal properties of the active layer in the Alaskan Arctic

Almost all biological activity in far north regions takes place within a shallow zone above the permafrost called the active layer. The active layer is the surficial layer of the soil system which thaws every summer. In Imnavait watershed, a small headwater watershed north of the Brooks Range on the North Slope of Alaska, the active layer is an extremely variable multilayered system consisting of a mat of mosses and sedges on about 10 cm of organic soil over silt. The layer of organic soil tends to mollify thermal and hydrologic fluctuations below it. The thermal conductivity of the surface organic layer at average moisture contents is about one-third that of the silt and thus functions as a layer of insulation for the permafrost. Before spring melt or after a period of low precipitation, the organic mat is desiccated and will absorb 1.5 cm of water before downslope runoff occurs. The hydraulic conductivity of the organic soils is 10 to 1000 times greater than the silt, thus during a large rainfall event, downslope movement will primarily occur in the organic layer. The subsurface mineral soil tends to remain saturated with little annual variation and shows little response to precipitation events. In comparison, the moisture content of surficial organic soil fluctuates between 10 and 90% by volume. To adequately model physical processes, we need a detailed understanding of the thermal and hydrologic properties because these properties vary so dramatically over short vertical distances.

Relative Abundance of Herpetofauna among Eight Types of Maine Peatland Vegetation

Relative Abundance of Herpetofauna among Eight Types of Maine Peatland Vegetation

Retention of needles and seeds on logs in Picea sitchensis – Tsuga heterophylla forests of coastal Oregon and Washington

Logs are a major seedbed in Picea sitchensis – Tsuga heterophylla forests; therefore, the interception and retention of seeds on these surfaces is a potential limitation on tree recruitment. The ability of log surfaces within Picea – Tsuga forests to retain needles and seeds was studied at Cascade Head Experimental Forest, Oregon. Moss- and litter-covered surfaces retained many (48–98%) of the seeds and needles placed on them, but rotten wood, sound wood, and bark of Tsuga heterophylla, Picea sitchensis, and Pseudotsuga menziesii retained few (0–8%). Examination of logs mapped in five Picea sitchensis – Tsuga heterophylla stands in Oregon and Washington indicated a mean projected log cover of 9.9%. Thin (<5 cm) and thick (>5 cm) moss mats were the most abundant log surfaces and covered 59 and 25% of the logs, respectively. Analysis of data on seedbed coverage, retentive characteristics, and seedbed-specific seedling survival indicated approximately 1% of a seed cohort would survive the 1st year on log surfaces.

Tree Seedlings on Logs in Picea‐Tsuga Forests of Oregon and Washington

Logs are the major seedbed for trees in coastal Picea sitchensis–Tsuga heterophylla forests. Field experiments were conducted at Cascade Head, Oregon, and Hoh River, Washington, to examine pathogens, predation, competition, and standing water as causes for this close seedling–log association. More seedlings survived on log blocks than on soil blocks, regardless of whether the blocks were raised or placed flush with the soil surface. Standing water was therefore an unlikely cause of the seedling–log association. Comparisons of plots protected from and exposed to predation revealed that predation was minor and of equal intensity on soils and logs. Sterilizing soils did not consistently increase seedling survival above controls. Clearing ground–layer vegetation from soil plots significantly increased the survival of conifer seedlings compared with that on uncleared soils. The seed penetration rates through moss mats indicated that <1% of the seedlings germinated within moss mats. Competition with herbs and mosses on the forest floor therefore appears to be responsible for the disproportionate number of tree seedlings found on logs. Recently fallen logs represent sites where competition is low enough for tree seedling recruitment within many Picea–Tsuga forests.

Evaluation of hydrological and biological influences on CO 2 fluxes from a karst stream

Carbon dioxide exchange is the fundamental process that drives calcite precipitation in a spring-fed travertine-depositing stream located in Augusta County, Virginia. Groundwater issuing at the surface springs that feed the stream is supersaturated with respect to atmospheric CO 2. CO 2 flux along the stream is attributed to physical outgassing caused by the steep concentration gradient between CO 2 dissolved in the stream water and its partial pressure in the atmosphere. The stream water is so rich in CO 2 that biological cycling does not significantly alter the mass flux. Outgassing is enhanced by hydrological agitation at the cascades. The local flux of CO 2 from the stream is greatest during the summer and fall. During those times, outgassing is driven by high dissolved CO 2 concentrations in the springs, warm temperatures, and low stream discharge. Seasonally, variations in the net flux of CO 2 from Falling Spring Run are minor. Outgassing drives the solution to high degrees of supersaturation with respect to calcite, yet calcite precipitation does not occur until the solution attains concentrations near five times supersaturation, high enough to overcome kinetic inhibition. Precipitation is greatest along the cascades where (1) hydrological agitation drives rapid loss of CO 2 and (2) benthic algal and moss mats and the travertine itself provide fresh surfaces for crystal growth. Calcite precipitation is greatest in the summer and fall when the local CO 2 flux is greatest.

Revegetation Experiments at Ny-Alesund, Spitsbergen, Svalbard

The effects of a commercial N-P-K fertilizer were studied on some native Svalbard plants on experimental sites located at Ny-Alesund, Spitsbergen (79?N). In experiment I, fertilizers were applied each year for a period of 5 yr. Experiment II was started in 1985 and the results from the 1986 investigation are given. The experiments show a variety of responses to N-P-K fertilizers. Fertilizers seem to have an immediate positive effect on flower production and vegetative growth. Preliminary results indicate accelerated seed germination and may also indicate a real increase in germination frequency. On denuded areas, a moss mat is established relatively rapidly when fertilizers are applied. The response to fertilizers seems to be species specific. Of the species tested it was only Luzula confusa that showed no or only a slightly positive effect following the application of fertilizers.

Bower Building and Decoration by the Bowerbird Amblyornis inornatus

AbstractBowers of the little‐known bowerbird Amblyornis inornatus are the most elaborately decorated structures erected by an animal other than humans. I studied populations in two mountain ranges. South Kumawa bowers consisted of a tower of sticks glued together, up to 2.6 m high, resting on an almost perfectly circular mat of black moss. Decorations were black, brown, or grey: leaves, snail shells, acorns, sticks, stones, and elytrae. The mat, decorative sticks, and elytrae were painted shiny black, possibly with an oily material in excrement. Another group of bowers 8 km distant differed in also using colored fruits as decorations. Wandamen bowers differed drastically in the much lower stick tower, woven but not glued, covered with a stick hut up to 2 m in diameter, resting on an unpainted green moss mat, and decorated with colored fruits, flowers, fungi, butterfly wings, and leaves. Objects tended to be grouped by color, with certain types of objects at specific locations. Within either mountain range there was individual and age‐related variation among bowers. Many or most decorations were objects commonly available in the forest. Decorations turned over from day to day.Wandamen birds were tame. The diverse vocalizations included vocal mimicry. Males raided each others' bowers and chased off other bird species. Bowerbirds may modify their environment by dispersing fresh fruits used as decorations, dispersing seeds of fruit eaten, and caching fruit.Colors of objects used as decorations are not a passive sample of locally available objects, nor do they necessarily match the plumage of females or of rival males, nor are they necessarily rare or habitat‐specific. Instead, color preference and many other features of bower design appear to be arbitrary characteristics of species or populations. I suggest that bower style is partly learned, and that geographic variation in bower style may depend upon culturally transmitted behavior, analogous to geographic variation in bird song dialects.

Adaptive Radiation of Salamanders in Middle American Cloud Forests

Adaptive Radiation of Salamanders in Middle American Cloud Forests

Animal art: Variation in bower decorating style among male bowerbirds Amblyornis inornatus

Courtship bowers of the bowerbird Amblyornis inornatus, the most elaborately decorated structures erected by an animal other than humans, vary geographically and individually. Bowers in the south Kumawa Mountains are tall towers of sticks glued together, resting on a circular mat of dead moss painted black, and decorated with dull objects such as snail shells, acorns, and stones. Bowers in the Wandamen Mountains are low woven towers covered by a stick hut with an entrance, resting on a green moss mat and decorated with colorful objects such as fruits, flowers, and butterfly wings. Young males build simpler bowers, and adult males differ among themselves. Experiments with poker chips of seven colors offered as decorations showed that individual birds prefer some colors over others, individuals and populations differ in these preferences, certain objects are placed in specific parts of the bower, and birds steal chips from neighbors. Bower style may be partly learned. Hence, geographically varying bower styles may be a culturally transmitted trait, like human art styles.

Vegetation sequence on three boreal Manitoban rock outcrops and seral position of Opuntia fragilis

The vegetation sequence on granitic outcrops containing Opuntia fragilis (Nutt.) Haw. was examined at three sites in southeastern Manitoba. The experimentally determined species sequence supported those in the literature: (0) bare rock – pioneer lichens, (1) primary moss mat, (2) secondary moss and lichen mat, (3) tertiary moss and lichen mat, (4) stress-tolerant ruderals, (5) stress-tolerant perennials, (6) perennial grasses, and (7) chamaephytes and phanerophytes. The primary factor determining the sequence was substrate depth, presumably because of its effect on moisture retention. The species composition of the earliest seral stages (0–3) was consistent at all three sites, presumably as a result of propagule availability and the extremely xeric nature of the sere. Variations in the species of subsequent stages may be attributed to the more restrictive dispersal mechanisms of mesic species. Local variations in vegetation scale and pattern were caused by slope, disturbance, crevices or depressions, and encroachment of forest at the forest–outcrop ecotone. Opuntia fragilis, a stress-tolerant perennial, was the first vascular plant in the sequence and colonized mats in stage 2 (occasionally 3). It did not persist in stage 5.

Plant community development in the Byron-Bergen Swamp: marl-bed vegetation

Comparative and Gaussian ordination were used to elucidate vegetational pattern on marl beds in the Byron-Bergen Swamp, Genesee County, NY. The ordinations reflected the physiognomic gradient seen in the field. The gradient consisted of algae in marl pools, short sedges on a low moss mat, tall sedges and short shrubs on low hummocks, and tall shrubs and shrubby trees on larger hummocks. Early invasional patterns are related to the formation of a moss–sedge mat which is further modified through the formation of mounds of various dimensions. Marl sites are invaded by species with differing invasional strategies. Included are mat-forming mosses and sedges which reproduce by rhizomes, seed, and (or) layering. These mats are modified through mound formation by cespitose sedges and by mosses such as Drepanocladus revolvens and Campylium stellatum and through organic matter deposition by all of the higher plants. This results in a general increase in peat depth overlying the marl. Differences exist along the physiognomic gradient from short sedges to tall sedges and short shrubs to tall shrubs and shrubby trees. Carbonate carbon decreases, whereas soil organic matter and cation-exchange capacity increase. There are also increases in the depth to and annual fluctuation in the water table. Stratigraphic cores suggest that this physiognomic gradient is a successional gradient as well. Analyses of these cores indicated significant increases of pH and bulk density with depth as well as decreases in organic matter and cation-exchange capacity, indicating an accumulation of organic matter over the surface of the marl. Tree cores indicate that the surrounding Thuja occidentalis forest is encroaching on the marl beds.

Tundra plant structure and production in relation to the environment

The alpine and polar climatic limit for growth of woody plants is very much dependent on the mean temperatures of the warmest three or four summer months. Tundra plants with perennating buds close to the ground are sheltered by insulating snow cover. Many tundra plants can grow at temperatures 5–10°C below 0°C and also have low optimum temperatures. Total net production of tundra plants may be as high as 900 g/m2/yr as dry weight in moist and eutrophic low alpine shrub tundra and in antarctic moss mats. The variation in tundra plant production is often observed to be greater between different stands (communities) within one locality than between localities, because of very important variation in soil moisture and nutrients between the stands. On a global scale the biomass of vascular plants increases by an order of magnitude from the climatic severe polar desert to semidesert and again from there to moist shrub tundra. The cryptogam biomass increases only 2–10 fold from polar desert to low arctic shrub tundra. To a certain limit unfavourable climatic conditions are worse to above- than to belowground plant parts. Highest root biomass compared to top (up to 20 times higher) is observed in wet monocotyledonous polar and alpine communities. In polar desert root biomass is small again, as compared to tops and also in lower latitudes and altitudes of temperate regions.

Vegetation of Pleistocene block streams and block fields in Victoria: a successional interpretation

Block fields and block streams above 1000 m on Mt Wombargo and Mt William, in northeastern and western Victoria respectively, were found to be in various stages of colonization. Plant succession was influenced by slope, altitude, precipitation, fire and the nature of the boulder accumulation. Lichen colonization was abundant on exposed surfaces. Soil build up, which commenced at deeper levels amongst the boulders, was hastened by the development of moss mats, and in particular by the accumulation of litter from adjacent eucalypt forest and woodland.

Changes in Arctic Eriophorum Tussock Communities Following Fire

The arctic cottongrass (Eriophorum vaginatum ssp. spissum) tussock community is susceptible to fire even though it has a relatively small aboveground standing crop and the peaty substrate is wet even in years of low precipitation. While burns can be severe enough to kill all aboveground plant parts, differential protection is provided new shoots by tussocks bases, moss mats, and peat. Plant succession following fire was unique in that no new species invaded the area. Growth came principally from root stocks protected by the organic surface. Cottongrass and Carex spp. were the first to show regrowth following a June fire at one site. The role of cottongrass seedlings in colonizing these tussock communities was minor, because few seedlings older than 1 year were found on any of the sites. Epilobium angustifolium ssp.angustifolium and some Calamagrostis canadensis ssp. canadensis originated from seed although most plants of the latter species had long vigorous rootstocks. These plants occurred as minor components in the undisturbed community and increased when fire destroyed the competing species. The charred organic surface, being very dark, absorbed more short wave energy and the active layer depth increased by 35 to 50% in June and as much as 25% by late autumn. The same thermal regime was found in burns several years old. This warmer soil mass, over a longer period of time, was conducive to better growing conditions. Annual plant production had almost recovered after two growing seasons, and nutrient content of the plants was higher in the burned area. This may be due to the greater soil mass available for root exploration, to nutrient release by fire, and to greater microbial activity in the warmer soils. If other tundra communities respond to fire in a similar manner as cottongrass tussock communities, fires may act as a rejuvenating factor, as they do in other biomes

Drought Resistance in Subalpine Nymphs of Somatochlora semicircularis Selys (Odonata: Corduliidae)

Somatochlora semicircularis inhabits subalpine pools and water meadows which frequently or regularly dry up in late August and early September. Since the nymphs require 4 years to mature, they must have the ability to survive these periods of drought. Somatochlora nymphs were found under rocks, moss mat, logs and deep in the bases of sedge clumps in Irwin Pond, Colorado. after it had dried up. In the laboratory, nymphs of Somatochlora die after losing the same relative amount of body water content under experimental desiccating conditions as do nymphs of Aeschna interrupta interna and Libellula quadrimaculata. However, it takes the nymphs of Somatochlora almost twice as long to reach this noint. Low rate of transpiration in the nymph and early formation of the snow pack over the dry subalpine pond are believed to contribu.te to the survival of this dragonfly.