Meadow Grass Research Articles

Fields of stress - Some measurements of the in-situ stress in a meadow in the Cambridgeshire countryside : Dalton, J C P; Hawkins, P G Ground Engng, V15, N4, May 1982, P15–22

Tests to measure in-situ soil stress were carried out to examine an alleged defect in a Cambridge self-boring pressuremeter. A circular map of in-situ horizontal stress was prepared for one borehole together with an evaluation of major and minor horizontal stresses at 25 locations at three other boreholes. The tests were carried out in a gently sloping, remotely situated, grass meadow. Although considered simple to carry out the tests showed that major and minor in-situ stresses in the horizontal plane may, contrary to popular belief, differ by as much as three to one and that this does not indicate instrument error. Details of the test procedure are given with results of lift-off pressure measurements. (TRRL)

Growth effects of SO2 and/or NO2 on woody plants and grasses during spring and summer

The two most widespread air pollutants in Britain are SO2 and NO2 (refs 1, 2). These not only contribute to acidity in rain3, which may seriously affect plant growth, but also cause substantial effects by their direct action as gaseous pollutants. Research into the effects of the gaseous pollutants on grasses has shown that the combination of SO2 and NO2 may be particularly toxic to plant growth4,5. Further research in this laboratory showed that Phleum pratense L. was more sensitive to SO2 when growth was slow and it was suggested that exposures during winter may be particularly phytotoxic6. Here we present the results of experiments in which serious effects on plant growth were detected even during the summer months. Autumn-sown smooth stalked meadow grass (Poa pratensis L.) exposed to SO2 or SO2 plus NO2 showed marked growth reductions during the winter and spring, and although the plants recovered during the summer, flowering was inhibited. Moreover, four broad-leaved tree species showed substantial decreases in growth when exposed to SO2 plus NO2 between March and August.

Indirect measurement of the latent heat flux of meadow grass from the energy balance — The sensible heat flux being measured by using the correlation technique

Direct measurements of net radiation, soil heat and sensible heat fluxes are continuously taken over a grass surface at Schoonheeten, The Netherlands. The data are integrated over 1-hr. intervals and the sensible heat is measured by using an eddy correlation technique. The results show no phase lag between sensible heat and radiation densities and a phase lag of ∼1 hr. between sensible heat and latent heat densities. A comparison is given between the real evaporation and the potential one.

Properties of Sea Grass and Sand Flat Sediments from the Intertidal Zone of St. Andrew Bay, Florida

Organic and carbonate carbon and textural properties of the substrates underlyingHalodule wrightii andThalassia testudinum sea grass beds in the intertidal zone of St. Andrew Bay, Florida were compared to adjacent unvegetated sand flats by physiographic divisions within the bay and to the subtidal slopes of the bay. Sea grass and sand flat sediments were principally fine-grained quartz sands. The mean particle-size of the sea grass sediments were finer-grained than those of the sand flats only in the west arm and lagoon of the bay. Size-frequency distributions of the sea grass sediments were generally slightly more negatively skewed and more leptokurtic than those of the sand flats. The sea grass sediments were less well sorted than were the sand flat sediments. The average organic and carbonate carbon contents of the sea grass beds were 1.9-fold greater than that of the sand flats but much less than that of the subtidal sea grass meadows. In the areas of pollution, sea grasses were absent; near this areaHalodule wrightii was the dominant sea grass.

Destruction of Nests by the Short-Billed Marsh Wren

-Short-billed Marsh Wrens (Cistothorus platensis) examined experimentally offered nests of Red-winged Blackbirds, Yellow-headed Blackbirds, Long-billed Marsh Wrens, and conspecifics. They also pecked eggs of Zebra Finches, Long-billed Marsh Wrens, Red-winged Blackbirds, and Cinnamon Teal, and once a male wren also pecked nestling Red-winged Blackbirds. Marsh wrens broke all small eggs, but the largest (teal) eggs survived the wrens' attacks. Results suggested that Short-billed Marsh Wrens attack eggs regardless of their size and color, but can destroy only small eggs. These wrens probably have a significant impact on nesting success of other small sympatric birds, including conspecifics. By destroying nests, Shortbilled Marsh Wrens probably exclude other birds from the vicinity of their activity centers and thereby reduce interference from them. Among all temperate zone passerines, marsh-nesting birds suffer the highest nest mortality rates, mainly through predation (Ricklefs 1969). Predators include raccoons, mink, hawks, owls, jays, crows, and water snakes (Allen 1914, Bent 1958, Robertson 1972). Other studies have shown that one of the most important predators destroying nests of marsh-dwelling passerines in North America is the Long-billed Marsh Wren (Cistothorus palustris; Allen 1914, Orians and Willson 1964, Burt 1970, Verner 1975, Picman 1977a, 1980). Destruction of nests by small passerines appears rare, but has been observed in several species of wrens, including the House Wren (Troglodytes aedon; Kendeigh 1941); Long-billed Marsh Wren (Allen 1914); Cactus Wren (Campylorhynchus brunneicapillus; Anderson and Anderson 1973); and Bewick's Wren (Thryomanes bewickii; Picman, pers. observ.). This indicates that nest-destroying behavior might be a common feature of the wren family. In this study, we investigated nest-destroying behavior of another wren, the Short-billed Marsh Wren (Cistothorus platensis) which breeds on wet sedge and grass meadows adjacent to marshes of eastern and central North America (Bent 1948). This species frequently is sympatric with Redwinged Blackbirds (Agelaius phoeniceus), Long-billed Marsh Wrens, Common Yellowthroats (Geothlypis trichas), Savannah Sparrows (Passerculus sandwichensis), Henslow's Sparrows (Ammodramus henslowii), Swamp Sparrows (Melospiza georgiana), and Song Sparrows (Melospiza melodia; Walkinshaw 1935, Bent 1948, Kroodsma and Verner 1978, this study). Nest destruction by this wren, therefore, might present an important factor reducing reproductive success of these and possibly other marsh-nesting birds. The questions we asked during this study were: (1) Do Short-billed Marsh Wrens normally destroy nests? (2) What kinds of nests and eggs will these wrens attack? (3) Do they attack nestlings? (4) Do affected species interact behaviorally with Shortbilled Marsh Wrens? (5) Why do these wrens attack nests with eggs or young?

L'alimentation estivale du campagnol des champs, Microtus pennsylvanicus, Ord.

Stomach content analyses performed on 272 meadow voles (Microtus pennsylvanicus) revealed that the animal feeds on 35 of the 45 species of plant present in its habitat. Timothy is the most abundant and the most common plant in the vole's diet. The abundance of the plants sampled in the habitat is positively correlated with the abundance of the plants found in the stomach contents. However, some species, like meadow grass (Poa spp.), aredefinitely preferred by the voles since they appear more frequently in the stomach contents than in the habitat. Some feeding habits are also sex dependent.[Translated by the journal]

Use of water by six grass species. 1. Dry-matter yields and response to irrigation

SUMMARYThe yield and quality of herbage produced by six grasses (perennial ryegrass, cocksfoot, timothy, rough-stalked meadow grass, tall fescue and Italian ryegrass) were examined both without irrigation and under two irrigation regimes. Water was applied according to the potential soil water deficit (potential SWD): the soil was either partially returned to field capacity (FC) after each cut or fully returned to FC whenever the potential SWD reached 25 mm. The swards were cut either at 3 (C3) or 6 (C6) week intervals over a 2 year period.Partial irrigation increased yields by 12–14% in the first year and by 36–58% in the second. Full irrigation produced little more growth than partial irrigation in the first year (maximum SWD, 188 mm) but increased yield by 78–93% in the second, very dry, year (maximum SWD, 311 mm). Under treatment C3 response per unit of water applied was similar with both partial and full irrigation, but under C6 the response was greater with partial (2·86 kg D.M./m3) than with full irrigation (1·79 kg D.M./m3).There were marked differences between the species in their ability to grow under drought conditions in the second year of the experiment. Without irrigation, roughstalked meadow grass and Italian ryegrass did not survive the drought. The performance of tall fescue was markedly superior to both perennial ryegrass and cocksfoot in these conditions. Of the surviving grasses timothy made least growth.

Use of water by six grass species. 2. Root distribution and use of soil water

SUMMARYThe use of soil water by six grasses (perennial ryegrass, cocksfoot, timothy, rough stalked meadow grass (RSMG), tall fescue and Italian ryegrass) was measured over 2 years. The swards were cut either at 3-week (C3) or 6-week (C6) intervals. In both years the maximum soil water deficit attained under C6was greater than under C3. Following several of the cuts from C6there was a marked, although temporary, reduction in the rate of water uptake.An extended dry period in the second harvest year revealed substantial differences in the total water used and in the patterns of uptake from the soil profile by the grasses. Effective depths of utilization of water under treatment C6were: RSMG, 40 cm; timothy, 70 cm; cocksfoot, 70 cm; perennial ryegrass, 80 cm; tall fescue > 100 cm. This order of depth of utilization corresponded with the order of yields obtained during drought conditions. An examination of the root systems of four grasses also showed that, particularly under treatment C6, roots of tall fescue were more numerous at depth than those of timothy, cocksfoot or perennial ryegrass, and under this treatment it showed its greatest tolerance to dry conditions. Drought tolerance in these grasses appears largely determined by the volume of soil exploited by the roots for water.

Some Determinants of the Composition and Abundance of Motile Macroinvertebrate Species in Tropical and Temperate Turtlegrass (Thalassia testudinum) Meadows

Monthly data on motile epibenthic macroinvertebrates inhabiting subtidal tropical (Panama') and warm temperate (U.S.A.) turtlegrass (Thalassia testudinum) meadows were gathered to test the hypothesis that structurally similar habitats will support similar numbers of species, regardless of latitude. Taken at face value these data do not support the hypothesis; species richness was significantly greater in Panama'. However, based on observational evidence as well as previously published natural history information it appears that the Panamanian sea grass meadows are effectively more structurally complex than those in Florida. This is primarily due to the presence of nearby coral reefs which support several invertebrate and many fish species which treat the coral reef - seagrass habitat as a single entity. In addition, many more vagrant species were taken in the tropical collections, as a result of the proximity of many other distinct habitats in Panama. Differences in total macroinvertebrate abundance between the two study areas seem to reflect differences in seasonal fluctuations of their fish predators, and in the species composition and biological activities of the fishes themselves. The predation and disturbance hypotheses can also be advanced to explain the results of this study. Although neither one of them seems to be correct, both are compatible with the data presented here. This suggests caution in accepting the mechanisms implied by hypotheses making very general predictions on community organization, when no independent information exists to verify them.

The “evaporation brush”, an evaporimeter for measuring the potential evaporation of meadow grass

A new type of evaporimeter, called the “evaporation brush” is described. It measures continuously the evaporation rate. The operation of the evaporation brush has been tested in a field of meadow grass, sufficiently supplied with soil moisture. It is found that the evaporation measured by this device in meadow grass during periods of 1 h and 24 h compares well with calculated data for meadow grass from a modified Penman formula. The instrument needs only to be tended once a week.

A GEOGRAPHICAL ANALYSIS OF QUANTITATIVE MORPHOLOGICAL VARIATION IN THE GRASSHOPPER ARPHIA CONSPERSA.

The speckled rangeland grasshopper, Arphia conspersa Scudder (Acrididae; Oedipodinae) ranges from Alaska and northern Canada to northern Mexico, and from California to the central Great Plains (Strohecker et al., 1968; Vickery, 1967; Helfer, 1953). Its altitudinal range is also quite wide, being from less than 1,000 m above sea level to nearly 4,000 m in the southern portion of the range (Alexander and Hilliard, 1969). Over this entire area the animal is springbrooded, the actual time of adult emergence being dependent on the onset of spring and final melt of winter snow. The distribution pattern of A. conspersa within this extensive geographic and topographic range is highly discontinuous, owing to its narrow habitat preferences and distinctive behavior patterns (Alexander and Hilliard, 1969; Willey and Willey, 1967, 1969,1971). Ecologically, the species is limited to shortgrass prairies and forest or brushland openings, areas in which the animal's primary food sources, narrow-leaved grasses, are found interspersed with numerous small spaces of bare ground which are necessary for the performance of courtship rituals. Hence, dense forest, tall grass meadows, and xeric scrubland are uninhabited by A. conspersa, while ecotonal habitats, such as roadside meadows and old logged areas, may be slowly colonized (Willey and Willey, 1971). Moderately grazed pastures can also support large populations. Within such a habitat structure, A. con-

Growth of selected fungi on leaf-protein supernatant

Some 19 strains ofAspergillus niger,A. oryzae, andPaccilomyces spp. are tested for their ability to grow on the supernatant remaining after the expressed juice from sugar beet tops and meadow grass has been heat-treated to precipitate crude ‘leaf protein’, and supplemented as required by glucose or ammonium sulphate. With effective strains ofA. niger,A. oryzae,P. elegans orP. variotii and an optimized carbohydrate/nitrogen ratio, over 70% of the organic content of the supernatant is rapidly converted into mycelial biomass of high protein content.

The Cost of Reproduction in Annual Meadow Grass

Studies of the evolution of life histories assume that there are costs to reproduction, although there is little experimental evidence for their existence. In this paper some populations of annual meadow grass (Poa annua L.) are analyzed, to test for the existence of these costs. The results show that there is a price to be paid for high rates of reproduction early in life, in lower rates and smaller plant size subsequently. There are also signs that high rates of reproduction very early in life increase subsequent risks of mortality. A possible form for the relationship is considered from a model of reproduction, growth, and survival. The implications of the observed and predicted costs to the evolution of life histories in annual meadow grass are discussed.

Control of Grasshoppers on Lawns, Bozeman, Montana, August 1978

Abstract Plot size for each rate (2 and 4 oz ai/acre) of 3 candidate insecticides was 0.01 acre of lush meadow grass mowed to theheightof the typical lawn. There plots were divided into 4 equal 0.0025-acre subplots, each representing one replication. A knapsack compressed air sprayer was used to treat each subplot with insecticide diluted in one quart of water (i.e., 100 gal/acre). Immediately after spraying, a 1/2 yd2 cage was secured on the still-wet grass in each subplot, and 20 adult grasshoppers were placed into each cage. There was an untreated check for each of the 3 materials.

The effect of constant and alternating temperatures, rinsing, stratification and fertilizer on germination of some weed species

The effect of constant and alternating temperatures, rinsing, stratification and application of a fertilizer solution on germination of 4 weed species was studied. The seeds of Matricaria chamomilla L. (mayweed) and Poa annua L. (annual meadow grass) achieved almost 100% germination under any condition. For Solanum nigrum L. (black nightshade) an alternating temperature was necessary for germination. The germination percentage of this species was also improved by a cold pretreatment. For Thlaspi arvense L. (stinkweed) a high germination percentage was obtained only when stratification, alternating temperature and a fertilizer solution were applied.

A field course based on the community energy flow approach

The concept of community energy flow provides an excellent basis for a field course (a) because simple methods are available for estimating the role of all the interacting components of a community and (6) because results of the series of related investigations can be arranged to provide an acceptable model of community structure and functioning. The study area was part of an uncut, ungrazed, rough grass meadow. A grid was set up and estimates were made of density and biomass of all the faunal components of the community. The contributions of the different components (including the icroorganisms) to community metabolism were assessed. The paper describes the methodology for estimating all these parameters and, in addition, for monitoring physical environmental variables. The flow of energy through the grassland community is not evenly distributed over the 24 hours of the day. Diurnal rhythms of activity of the larger invertebrates were recorded by means of periodic ‘sweep-netting’ and ‘pitfalling’. The paper culminates, as does the field course, in the construction of a model of energy flow through the community. We point out that this approach is very flexible, both in terms of students and of ecosystems.

Feeding rates, search paths, and surveillance for predators in great-tailed grackle flocks

Feeding rates, search paths, and surveillance behaviour of great-tailed grackles were measured to test the hypotheses that flocking influences: (a) feeding rates, (b) search behaviour, and (c) predator detection.Peck rates of grackles feeding on open grass meadows in Gatun, Panamá Canal Zone, did not vary with flock density and variation in peck rates was also independent of density. When grackles were in denser flocks, their search paths were straighter and, during the wet season only, they moved slower in denser flocks. Female grackles in denser flocks paused less often to scan the surrounding environment, presumably for potential danger.Although they were not strongly influenced by flocking, feeding and search behaviour of grackles was strongly affected by the sex of the grackles, the season, and the local feeding area. Grackle feeding behaviour hence seemed less closely adjusted to flocking than to other environmental factors.

Interdisciplinary (Biology/Geology) Field Study in Bermuda

A short course on organism-sediment relationships can be taught effectively in Bermuda during a mid-term vacation. Facilities of the Bermuda Biological Station and a sub-tropical climate are well suited to field studies of coral reefs, “boiler” reefs (coralline algae and vermetid gastropods), carbonate diagenesis, sediment genesis, benthic marine invertebrates, and tropical marine communities (including mangrove swamps and sea grass meadows). Initial orientation by lectures, readings, and field trips provide the background for students to carry out individual research projects.

La signification gèographique de l'irrigation dans le Gudbrandsdal septentrional — et plus particulièrement dans la vallée de l'Otta

Cultivation of grain (primarily of barley) plays an important role in the upper part of the Gudbrandsdal region in eastern Norway, and especially in the Otta valley, a western branch to the main valley. The grain is primarily used for feeding the area's large stock of cattle and pigs. The big cattle population per hectare of the farmland to a large extent explains the high revenue from agriculture in the area. Grain cultivation seems quite extraordinary in a mountain area at this latitude. But the valleys in northern Gudbrandsdal, and especially the Otta valley, deeply carved into the large mountain massif of the Scandinavian peninsula, take advantage of a unique lee situation against the humid western winds. Aridity makes irrigation a prerequisite to grain growing and even meadow grass, and it has been practised since far back in history. The grain harvest is usually satisfactory thanks to the irrigation and also to the high amount of sunshine in the area, where cloudiness is rare as a consequence of the lee effect. These two factors help to bring the grain to maturity.

Effect of vegetation on lateral migration of anastomosed channels of a glacier meltwater river

A series of experiments were performed on bank materials of anastomosed channels in flood-plain silt deposits in the Alexandra Valley in Banff Park, Alberta, to determine the effect of vegetation roots on bank erodibility and lateral migration of channels. Underground roots from the dense growth of meadow grass and scrub willow provide the reinforcement of bank sediment and a riprap-like protection of channel banks from river erosion. Results from the experiments suggest that in cool environments with aggrading river conditions where overbank deposition of silt, clay, and fine sand dominate the valley fill, vegetation roots are able to rapidly accumulate and decay very slowly, thus affording protection to banks from erosion in deeper parts of the channels. Experiments were performed with a specially designed erosion box, used as a means to simulate natural erosion conditions and measure the influence of vegetation roots in reducing bank erosion. Results indicate that the bank sediment with 16 to 18 percent by volume of roots with a 5-cm root-mat for bank protection, typical of the area, had 20,000 times more resistance to erosion than comparable bank sediment without vegetation. Assuming five severe erosion days per year, potential lateral channel migration would amount to 4.2 cm per year. Such resistance, due to vegetation, accounts for the remarkable stability of channels during the last 2,500 yr in the Alexandra Valley.