Grazing response strategies along a snow deposition gradient: a laboratory experiment on three grass species from Svalbard

1997 ◽  
Vol 75 (10) ◽  
pp. 1685-1691 ◽  
Author(s):  
Christina Wegener ◽  
Ann Marie Odasz
Keyword(s):  
Grass Species ◽  
Total Biomass ◽  
Response Patterns ◽  
Response Strategies ◽  
Plant Parts ◽  
Svalbard Reindeer ◽  
Grazing Response ◽  
The Cost ◽  
Deposition Gradient ◽  
Snow Deposition

The objective of this study was to determine whether Arctic grasses from different sites along a snow deposition gradient respond similarly to grazing. The effects of laboratory simulated grazing (two levels of clipping frequency, clipping height, and nutrition) on accumulated biomass of different plant parts and number of tillers were measured in the reindeer forage grasses Poa arctica R. Br. from a dry ridge habitat, Festuca rubra L. from a moist lee-side habitat, and Deschampsia alpina L. from a wet snowbed habitat in Svalbard. Both P. arctica and F. rubra increased the proportion of biomass allocated belowground at the cost of the aboveground structures in response to high clipping frequency combined with high clipping height, leaving total accumulated biomass unchanged. In D. alpina, on the contrary, the percentage of aboveground biomass increased at the cost of belowground structures in response to high clipping frequency and low clipping height. This results in higher vulnerability to clipping and reduced total biomass. These two contrasting response patterns may reflect differences in adaptations in the habitats. Stress tolerance is more important on wind-blown ridges and in lee-side habitats where the grazing season is longer. On the other hand, rapid growth is more important in the snowbed where the growing season is shorter. These strategies may be of great importance in regulating and driving the local foraging patterns of Svalbard reindeer. Key words: herbivory, Arctic, graminoids, plant strategy, forage.

scholarly journals Buried but unsafe – defoliation depletes the underground storage organ (USO) of the mesic grassland geophyte, Hypoxis hemerocallidea

2021 ◽  
Author(s):  
Craig Morris
Keyword(s):  
Growing Season ◽  
Grass Species ◽  
Underground Storage ◽  
Total Biomass ◽  
Plant Parts ◽  
Mesic Grassland ◽  
Previous Season ◽  
Carry Over ◽  
Stored Reserves ◽  
Hypoxis Hemerocallidea

Mesic grasslands in South Africa (> 650 mm a-1 MAP) are rich in herbaceous forbs, which outnumber grass species by more than 5 to 1. Many of these forbs have underground storage units (USOs), such as thickened rootstocks, rhizomes, bulbs, or corms, that provide resources (non-structural carbohydrates, minerals, and water) enabling them to resprout after dry, frosty winters, and fire. However, despite their extensive biomass and reserves ostensibly protected underground, geophytic mesic grassland forbs can be severely depleted or extirpated by chronic trampling and grazing of their aerial parts by livestock. This study examined a possible explanation for forb demise in overgrazed grassland by investigating, in a pot trial, whether the growth of forbs and the size of their USOs are negatively affected by simulated green leaf loss. In a 2x2 factorial (clipped vs. unclipped x spring regrowth in the dark vs. light), five replicate plants of Hypoxis hemerocallidea, a common mesic grassland forb that resprouts from a corm, were subject to six severe (clipped to 80 mm) defoliations during the growing season and regrown in spring under full or restricted light to measure stored reserve contribution to regrowth. Defoliated plants were resilient to defoliation during the growing season, matching the total biomass production of unclipped plants, though cutting reduced the number of leaves by ~60% and flowers by almost 85%. Spring regrowth on stored reserves equalled that from reserves plus concurrent photosynthesis, indicating the value of USOs for regrowth. However, there was a marked carry-over effect of previous season defoliation, resulting in a one-third reduction in shoot growth and 40% fewer inflorescence in spring. Crucially, corm mass was more than halved by clipping. Above-ground spring growth was linearly related to corm mass. It was concluded that buried stored reserves are not protected by recurrent disturbance to aerial plant parts and that continued diminishment of USOs under chronic disturbance by overgrazing or frequent mowing would weaken and likely eventually kill plants, reducing forb species richness. Lenient management by infrequent summer mowing or grazing at moderate stocking rates combined with periodic rotational full season resting and dormant-season burning is recommended to maintain the USOs and vigour of forbs in mesic grassland.

Stimulus Ratio Effects on Speech Discrimination by Children and Adults

1991 ◽  
Vol 34 (3) ◽  
pp. 671-678 ◽  
Author(s):  
Joan E. Sussman
Keyword(s):  
Discrimination Task ◽  
Response Pattern ◽  
Response Patterns ◽  
Speech Discrimination ◽  
Adult Group ◽  
Discrimination Accuracy ◽  
Formant Frequency ◽  
Response Strategies ◽  
Place Of Articulation ◽  
Adults And Children

This investigation examined the response strategies and discrimination accuracy of adults and children aged 5–10 as the ratio of same to different trials was varied across three conditions of a “change/no-change” discrimination task. The conditions varied as follows: (a) a ratio of one-third same to two-thirds different trials (33% same), (b) an equal ratio of same to different trials (50% same), and (c) a ratio of two-thirds same to one-third different trials (67% same). Stimuli were synthetic consonant-vowel syllables that changed along a place of articulation dimension by formant frequency transition. Results showed that all subjects changed their response strategies depending on the ratio of same-to-different trials. The most lax response pattern was observed for the 50% same condition, and the most conservative pattern was observed for the 67% same condition. Adult response patterns were most conservative across condition. Differences in discrimination accuracy as measured by P(C) were found, with the largest difference in the 5- to 6-year-old group and the smallest change in the adult group. These findings suggest that children’s response strategies, like those of adults, can be manipulated by changing the ratio of same-to-different trials. Furthermore, interpretation of sensitivity measures must be referenced to task variables such as the ratio of same-to-different trials.

scholarly journals   Effect of elevated CO2 and temperature on phosphorus efficiency of wheat grown in an Inceptisol of subtropical India

2012 ◽  
Vol 58 (No. 5) ◽  
pp. 230-235 ◽  
Author(s):  
Manoj-Kumar ◽  
A. Swarup ◽  
A.K. Patra ◽  
J.U. Chandrakala ◽  
K.M. Manjaiah
Keyword(s):  
Grain Yield ◽  
Dry Weight ◽  
P Uptake ◽  
Utilization Efficiency ◽  
Phosphorus Efficiency ◽  
Total Biomass ◽  
P Efficiency ◽  
Plant Parts ◽  
P Fertilizer ◽  
P Utilization

In a phytotron experiment, wheat was grown under two levels of atmospheric CO<sub>2</sub> [ambient (385 ppm) vs. elevated (650 ppm)], two levels of temperature (ambient vs. ambient +3&deg;C) superimposed with three levels of phosphorus (P) fertilization: 0, 100, and 200% of recommended dose. Various measures of P acquisition and utilization efficiency were estimated at crop maturity. In general, dry matter yields of all plant parts increased under elevated CO<sub>2</sub> (EC) and decreased under elevated temperature (ET); however, under concurrently elevated CO<sub>2</sub> and temperature (ECT), root (+36%) and leaf (+14.7%) dry weight increased while stem (&ndash;12.3%) and grain yield (&ndash;17.3%) decreased, leading to a non-significant effect on total biomass yield. Similarly, total P uptake increased under EC and decreased under ET, with an overall increase of 17.4% under ECT, signifying higher P requirements by plants grown thereunder. Although recovery efficiency of applied P fertilizer increased by 27%, any possible benefit of this increase was negated by the reduced physiological P efficiency (PPE) and P utilization efficiency (PUtE) under ECT. Overall, there was ~17% decline in P use efficiency (PUE) (i.e. grain yield/applied P) of wheat under ECT. &nbsp;

Regeneration of Canada Thistle (Cirsium arvense) from Intact Roots and Root Fragments at Different Soil Depths

Weed Science ◽  
2013 ◽  
Vol 61 (2) ◽  
pp. 277-282 ◽  
Author(s):  
Mette Goul Thomsen ◽  
Lars-Olav Brandsæter ◽  
Haldor Fykse
Keyword(s):  
Cirsium Arvense ◽  
Total Biomass ◽  
Layer By Layer ◽  
Canada Thistle ◽  
Soil Layers ◽  
Plant Parts ◽  
Shoot Number ◽  
Two Factors ◽  
Intact Root ◽  
Intact Roots

In the present field study, the capability of Canada thistle to develop shoots from intact roots and root fragments at different soil depths was studied. The experiments were performed on four sites with high-density Canada thistle, with three or four replications per treatment. At each site, the soil in the plots was removed layer by layer (to 30 or 40 cm, depending on the site), within a 1 by 1-m quadrat, and spread out on a plastic sheet. All roots and other plant parts were removed, and the soil was either replaced without any root material (two sites), or the roots of the thistles were cut into 10-cm-long fragments and replaced into the source holes (two sites). The measured variables were shoot number and biomass. The number of shoots of Canada thistle decreased with increasing depth (P < 0.001) and increased with time. Additionally, the two factors interacted (P < 0.001) such that shoot development was slower from greater depths. Roots from ≤ 20 cm depth produced higher biomasses than did roots from below 20 cm depth. Replacement of root fragments did not affect the amount of biomass produced. It was concluded that the intact root system contributed considerably more to the total biomass produced by Canada thistle than did the root fragments in the upper soil layers.

Seasonal changes in the nutritive value of grass species in Spinifex pastures of Western Australia.

1988 ◽  
Vol 10 (1) ◽  
pp. 60 ◽  
Author(s):  
AM Holm ◽  
RJ Allen
Keyword(s):  
Western Australia ◽  
Nutritive Value ◽  
Grass Species ◽  
In Vitro Digestibility ◽  
Gulf Region ◽  
Plant Parts ◽  
The Common ◽  
Exmouth Gulf

This study was undertaken to assess whether the nutritional quality of spinifex pasture lands is improved by buming to promote the growth of grasses other than spinifex. We selected two comparable sites in the Exmouth Gulf region of Western Australia; one had been bumt in late 1979 and the other had not been burnt for many years. On these sites we sampled the five grass species present, as well as Triodia pungens (soft spinifex) and Plectrachne >chinzii (Oat eared spinifex) on 10 occasions from March 1980 to April 1982. Plant parts were analysed for nitrogen, phosphorus and sulphur content, and in vitro digestibility. None of the common grass species tested was more nutritious or more palatable than soft spinifex. It seems that little is gained from manipulating spinifex pastures through burning if the aim is to encourage alternative grass species. There is a need however for further studies into the importance of woody herbs and forbs in the nutrition of grazing animals on spinifex country and the effect of fire on these species.

The Investigation of Compliment Response Patterns across Gender and Age among Advanced EFL Learners

2016 ◽  
Vol 7 (4) ◽  
pp. 760 ◽  
Author(s):  
Parisa Yazdani Khaneshan ◽  
Alireza Bonyadi
Keyword(s):  
Speech Acts ◽  
Response Patterns ◽  
Speech Community ◽  
Efl Learners ◽  
Response Strategies ◽  
Communication Breakdown ◽  
Gender And Age ◽  
Compliment Responses ◽  
Cultural Standards ◽  
The Given

Compliment responses (CRs) as manifestations of social-cultural standards and politeness varieties of a certain speech community are prevalent types of speech acts which are vulnerable to be misunderstood and therefore cause communication breakdown. Having this in mind, the recent study aimed at investigating compliment response strategies of Iranian advanced EFL learners across gender and age. The data were collected through application of a Discourse Completion Task (DCT), borrowed from Chen and Yang (2010), with four situational settings (appearance, clothing, ability, and possession) to 50 male and 50 female advanced EFL learners of an English institute in Iran. Based on qualitative data analysis, no difference was shown between the CR strategies employed by male and female participants in terms of frequency. Likewise, it was revealed that the frequency of CR strategies used by teenage and adult groups was very close. However, scrutinizing the emerging themes, besides similarities between the given groups, some subtle differences in the terminology of the employed strategies were detected.

Restriction of a C3 grass to dry ridges in a semiarid grassland

1986 ◽  
Vol 64 (5) ◽  
pp. 1006-1011 ◽  
Author(s):  
Jessica Gurevitch
Keyword(s):  
Soil Moisture ◽  
Competitive Ability ◽  
Moisture Gradient ◽  
Grass Species ◽  
Vegetation Patterns ◽  
Total Biomass ◽  
Semiarid Grassland ◽  
Soil Moisture Gradient ◽  
Ordination Analysis ◽  
Photosynthetic Type

Contrary to generalizations about differences in the adaptive significance of C3 and C4 photosynthesis, Stipa neomexicana, a C3 grass, was restricted to the driest sites along a topographic and soil moisture gradient in a semiarid grassland in Arizona. The distribution of Stipa neomexicana was inversely related to the abundance of C4 grasses. The total biomass of C4 grasses increased from low values on ridge crests to maximum values on lower, wetter sites. Ordination analysis confirmed that the topographic and soil moisture gradient was the factor most closely associated both with grass species distributions and with total biomass and cover. Other factors, such as soil fertility, did not appear to be closely related to vegetation patterns. The data suggest that Stipa neomexicana was excluded from sites with greater soil moisture by competition with C4 neighbors. While it is likely that other factors besides photosynthetic type determine the ability to survive on the driest sites in this system, C4 photosynthesis appears to confer an advantage in competitive ability in microhabitats with greater amounts of soil moisture.

Effect of species, plant part, and season of harvest on n-alkane concentrations in the cuticular wax of common rangeland grasses from southern Africa

2001 ◽  
Vol 52 (9) ◽  
pp. 875 ◽  
Author(s):  
D. G. Smith ◽  
R. W. Mayes ◽  
J. G. Raats
Keyword(s):  
Southern Africa ◽  
Diet Composition ◽  
Common Species ◽  
Flower Head ◽  
Grass Species ◽  
Wet Season ◽  
Reliable Technique ◽  
Plant Parts ◽  
Plant Samples ◽  
Whole Plant

The use of plant alkane concentrations to measure diet composition of herbivores has been shown to be a reliable technique in animals grazing temperate, sown pastures that contain a relatively small number of plant species. There is potential to develop this technique for use with free-range animals foraging upon species-rich rangeland. In order for the technique to be effective, the alkane concentration patterns (ACP) of the component species of the diet must be distinct from one another. Common species of grasses from southern Africa were analysed for their alkane concentrations in order to evaluate the use of the alkane technique for measuring diet composition under complex rangeland conditions. The alkane profiles were determined in different plant parts from 40 grass species gathered during the wet season and 23 gathered during the dry season. Statistical analysis, using ANOVA, showed that there were highly significant differences (P < 0.001) in the C 25, C 27 , C 29 C 31 , C 33 , and C 35 alkane concentrations between flower head and stem during both the dry and wet seasons. Similar statistical differences were apparent in the C 25 , C 27 , C 29 , and C 31 alkane concentrations of leaf and stem during both seasons; differences in C 33 and C 35 concentrations were significant but at a lower level (P < 0.01 and P < 0.05, respectively). Differences in C 25 , C 27 , and C 29 alkane concentrations between flower head and leaf were only significant (P < 0.001) during the wet season. Statistical differences (P < 0.001) between whole plant samples obtained in different seasons were due to changes in the proportion of flower head, leaf, and stem. Cluster analysis often showed less similarity between plant parts of the same species than between whole plant samples of different species. It was concluded that ACPs measured in the selected species were probably too similar and thus, plants could not be identified using the alkane technique. However, it was possible to use the alkane technique to determine the proportions of flower-head, leaf, and stem in the diet.

Methodology for optimizing geographical distribution and capacities of biomass power plants in Sabah, East Malaysia

2014 ◽  
Vol 8 (1) ◽  
pp. 100-120 ◽  
Author(s):  
Yun Seng Lim ◽  
Siong Lee Koh ◽  
Stella Morris
Keyword(s):  
Power Plants ◽  
Transportation Cost ◽  
Real Data ◽  
Total Biomass ◽  
Biomass Waste ◽  
Content Type ◽  
Capital Costs ◽  
Total Capacity ◽  
The Cost ◽  
Biomass Power Plants

Purpose – Biomass waste can be used as fuel in biomass power plants to generate electricity. It is a type of renewable energy widely available in Malaysia because 12 million tons of the biomass waste is produced every year. At present, only 5 per cent of the total biomass waste in Sabah, one of the states in Malaysia, is used to generate electricity for on-site consumption. The remaining 95 per cent of the biomass waste has not been utilized because the transportation cost for shifting the waste from the plantations to the power plants is substantial, hence making the cost of the biomass generated electricity to be high. Therefore, a methodology is developed and presented in this paper to determine the optimum geographic distribution and capacities of the biomass power plants around a region so that the cost of biomass generated electricity can be minimized. The paper aims to discuss these issues. Design/methodology/approach – The methodology is able to identify the potential locations of biomass power plants on any locations on a region taking into account the operation and capital costs of the power plants as well as the cost of connecting the power plants to the national grid. The methodology is programmed using Fortran. Findings – This methodology is applied to Sabah using the real data. The results generated from the methodology show the best locations and capacities of biomass power plants in Sabah. There are 20 locations suitable for biomass power plants. The total capacity of these biomass power plants is 4,996 MW with an annual generation of 35,013 GWh. This is sufficient to meet all the electricity demand in Sabah up to 2030. Originality/value – The methodology is an effective tool to determine the best geographic locations and sizes of the biomass power plants around a region.

scholarly journals Fatty Alcohol Application to Control Meristematic Regrowth in Bottle Gourd and Interspecific Hybrid Squash Rootstocks Used for Grafting Watermelon

HortScience ◽  
2014 ◽  
Vol 49 (3) ◽  
pp. 260-264 ◽  
Author(s):  
Shawna L. Daley ◽  
Richard L. Hassell
Keyword(s):  
Fatty Alcohol ◽  
Interspecific Hybrid ◽  
Application Rate ◽  
Optimal Treatment ◽  
Bottle Gourd ◽  
Control Treatment ◽  
Treatment Rate ◽  
Plant Parts ◽  
Rate Interaction ◽  
The Cost

Application of fatty alcohol compounds to rootstock meristems can control rootstock meristematic regrowth, thus decreasing the cost of producing grafted watermelon transplants by reducing the labor. Eight rates of Fair 85® and Off-Shoot T®, two commercially available fatty alcohol compounds, were applied to the meristem region of bottle gourd (Lagenaria sicereria cv. Emphasis) and interspecific hybrid squash (Cucurbita maxima × Cucurbita moschata cv. Carnivor) rootstocks to determine the optimal application rate to control regrowth without damaging the remaining plant parts. A water-only control treatment was also included. Rootstock seedlings were rated for damage and regrowth on Days 1, 7, 14, and 21 after treatment. Damage increased and regrowth decreased with increasing rates of fatty alcohol compound. In addition, a significant compound-by-rate interaction indicated that inert ingredients in the fatty alcohol formulation have an effect on both damage and regrowth. The optimal treatment rate, e.g., providing at least 95% control of regrowth with less than 10% damage, was found to be between a 5% (Off-Shoot T®) and 6.25% (Fair 85®) fatty alcohol application. At the optimal treatment rate, no adverse effects to grafting success were observed in the grafting procedure.

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