scholarly journals Germination Responses of Several Poaceae Members towards Differential Storage Durations

2011 ◽  
Vol 3 (4) ◽  
pp. 44-50
Author(s):  
Krishna R. PANCHAL ◽  
Neeta R. PANDYA ◽  
Susy ALBERT ◽  
Dhara J. GANDHI
Keyword(s):  
Test System ◽  
Native Plant ◽  
Cenchrus Ciliaris ◽  
Themeda Triandra ◽  
Seed Collection ◽  
Grassland Community ◽  
Species Response ◽  
Heteropogon Contortus ◽  
Dry Storage ◽  
Dichanthium Annulatum

Concerns over biodiversity loss and increasing biological invasion have forced interest on assessment of the effects on native plant species diversity in grassland community. To observe different patterns of grass emergence (dormancy/germination) in the warm tropical grasslands of India, time span of a seed from the seedling stage to a mature plant becomes very crucial for the community development. In the present study seed germination response of six dominant species of the selected study area were tested to record the various effects of dry storage conditions on seed germinability. The species selected were Apluda mutica L., Cenchrus ciliaris L., Chrysopogon fulvus (Spreng.) Chiov., Dichanthium annulatum (Forsk.) Stapf., Heteropogon contortus (L.) P. Beauv. ex Roem. and Schult. and Themeda triandra (R. Br.) Stapf. For this purpose, seed collection at mature seed stage, seed processing and dry seed storage were followed by the germination test system. Obtained results are exhibited in the form of different responses such as, species response patterns towards capacity for immediate germination, responses to dormancy, dry storage and temperature fluctuation. The extent of the requirement in breakage of primary dormancy was highly correlated with the timing of seed maturity, precursors of seed dormancy and seed viability. In present screening out of the six studied species Apluda mutica, Cenchrus ciliaris and Dichanthium annulatum showed dependable germination pattern to fluctuating temperature. The correlation between viability and germination suggests that the germination of Apluda mutica, Cenchrus ciliaris and Themeda triandra are linearly dependent on the viability that the seeds of these species have. As these species showed less influence with the relative fluctuating environment, they can be stored for longer period and frequently can be use for community regeneration in pasture development.

Native plant diversity in tropical savannas decreases when exotic pasture grass cover increases

2012 ◽  
Vol 34 (2) ◽  
pp. 183 ◽  
Author(s):  
A. S. Kutt ◽  
J. E. Kemp
Keyword(s):  
Species Richness ◽  
Plant Diversity ◽  
Native Species ◽  
Perennial Grass ◽  
Native Plant ◽  
Pasture Grass ◽  
Grazing Land ◽  
Themeda Triandra ◽  
Heteropogon Contortus ◽  
Native Plant Diversity

The invasion of exotic plants into savanna ecosystems can disrupt the natural pattern of vegetation. Indian couch Bothriochloa pertusa was introduced into Australia as a species for rehabilitation of degraded grazing land. In this study the effect of increasing B. pertusa cover on native plant diversity and possible mechanisms of its spread were examined. Forty sites were sampled in uncleared Queensland rangelands with a range of B. pertusa and Bothriochloa ewartiana (a native species) cover. The mean number of native species per quadrat declined with increasing B. pertusa cover but remained stable over sites with increasing B. ewartiana cover. Mean species richness accumulated at a significantly lower rate for sites with B. pertusa present. Canonical analysis of principle coordinates suggested that three groups of sites, ranging from low to high species richness and cover of native plants, were correlated along gradients of B. pertusa cover, grazing intensity and basal area of dead trees. Generalised linear modelling indicated significant negative relationships between B. pertusa cover and total ground cover, forbs and perennial grass richness and cover, and cover of nine native perennial tussock grasses (Aristida leptopoda, B. decipiens, B. ewartiana, Chrysopogon fallax, Dichanthium fecundum, D. sericeum, Heteropogon contortus, H. triticeus and Themeda triandra). This study suggests that an increase in B. pertusa is associated with a substantial change in the cover and species richness of native plant communities. This was considered to occur via competitive effects as well as a result of cattle grazing, rainfall deficit and tree death. Regardless of the mechanism, continued spread of exotic pasture species has the potential to cause significant changes to rangeland biodiversity.

Effects of moisture supply in the dry season and subsequent defoliation on persistence of the savanna grasses Themeda triandra, Heteropogon contortus and Panicum maximum

1992 ◽  
Vol 43 (2) ◽  
pp. 241 ◽  
Author(s):  
JJ Mott ◽  
MM Ludlow ◽  
JH Richards ◽  
AD Parsons
Keyword(s):  
Growing Season ◽  
Close Correlation ◽  
Dry Season ◽  
Carbon Gain ◽  
Panicum Maximum ◽  
Wet Season ◽  
Themeda Triandra ◽  
Heteropogon Contortus ◽  
Moisture Conditions ◽  
Sheath Material

The close correlation between grazing-induced mortality and major climatic patterns in Australian savannas, led us to the hypothesis that moisture conditions during the dry, non-growing season could affect sensitivity to grazing in the subsequent growing season. Using three widespread savanna species (Themeda triandra, Heteropogon contortus and Panicum maximum), this hypothesis was tested experimentally and the mechanisms controlling this response examined and quantified. In T. triandra drought during the dry season led to major mortality in defoliated plants in the next growing season. This mortality was caused by a synchrony of tillering at the commencement of the wet season, leaving few buds for replacement once parent tillers were killed by defoliation. T. triandra was also the most sensitive species to defoliation. This sensitivity was due to the poor ability of the plant to maintain positive carbon gain after defoliation. Several factors contributed to this poor ability, including: low total photosynthetic rate, low specific leaf area, and a large proportion of sheath material with poor photosynthetic capacity remaining after cutting. Both H. contortus and P. maximum growing under irrigated and fertilized conditions did not display any effects of previous moisture treatments when defoliated during the next wet season and were much less sensitive to defoliation than T. triandra.

Vegetation change in the grasslands and grassy woodlands of east-central Cape York Peninsula, Australia

1998 ◽  
Vol 4 (2) ◽  
pp. 132 ◽  
Author(s):  
Gabriel M. Crowley ◽  
Stephen T. Garnett
Keyword(s):  
Vegetation Change ◽  
Perennial Grass ◽  
Aerial Photographs ◽  
Management Tool ◽  
East Central ◽  
Themeda Triandra ◽  
Species Dominance ◽  
Heteropogon Contortus ◽  
European Settlement ◽  
Cape York

The vegetation of 64 grassland and grassy woodland sites in east-central Cape York Peninsula, surveyed by CSIRO in 1966, was re-surveyed in 1995. While the original vegetation communities had persisted at most sites, a change in species dominance was recorded at 14% of sites. Melaleuca viridiflora (ti-tree) had invaded eight sites, and increased in abundance in at least 16 of the 35 sites in which it had occurred in 1966. This had led to four out of 13 grassland sites, and three out of four mixed evergreen sites being re-classified as ti-tree woodlands. Analysis of aerial photographs covering 415 km2 showed a 10% net loss of grasslands between 1969 and 1988. These changes are attributed to a reduction in the use of fire as a management tool since European settlement. Changes were also found in perennial grass composition consistent with grazing or over-grazing, particularly in the eucalypt/ironwood communities. A shift from Themeda triandra to Heteropogon contortus parallels earlier, grazing-related changes in southern Queensland. Evidence of a decline in Heteropogon triticeus and isolated losses of Sorghum plumosum are more suggestive of localized, unsustainable overgrazing. An increase in Sorghum plumosum in wet habitats appears to be associated with recent lack of burning. These changes suggest that further intensification of cattle grazing in the area may not be possible without significantly reducing both conservation values and pasture condition.

scholarly journals Potential Effects of the Loss of Native Grasses on Grassland Invertebrate Diversity in Southeastern Australia

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Roger Edgcumbe Clay
Keyword(s):  
South Australia ◽  
Grass Cover ◽  
Native Plant ◽  
Native Grass ◽  
Native Plant Species ◽  
Grassland Community ◽  
European Settlement ◽  
Southeastern Australia ◽  
Invertebrate Diversity ◽  
Invertebrate Biodiversity

Reduction in area of the southeastern temperate grasslands of Australia since European settlement has been accompanied by degradation of remaining remnants by various factors, including the replacement of native plant species by introduced ones. There are suggestions that these replacements have had deleterious effects on the invertebrate grassland community, but there is little evidence to support these suggestions. In the eastern Adelaide Hills of South Australia, four grassland invertebrate sampling areas, in close proximity, were chosen to be as similar as possible except for the visible amount of native grass they contained. Sample areas were surveyed in four periods (summer, winter, spring, and a repeat summer) using pitfall traps and sweep-netting. A vegetation cover survey was conducted in spring. Morphospecies richness and Fisher’s alpha were compared and showed significant differences between sample areas, mainly in the summer periods. Regression analyses between morphospecies richness and various features of the groundcover/surface showed a strong positive and logical association between native grass cover and morphospecies richness. Two other associations with richness were less strong and lacked a logical explanation. If the suggested direct effect of native grass cover on invertebrate diversity is true, it has serious implications for the conservation of invertebrate biodiversity.

Ruminal degradation characteristics of some African rangeland grasses

1995 ◽  
Vol 125 (2) ◽  
pp. 189-197 ◽  
Author(s):  
P. J. O'Reagain ◽  
B. C. Goetsch ◽  
R. N. Owen-Smith
Keyword(s):  
Cell Wall ◽  
Dry Matter ◽  
Agricultural Development ◽  
Cynodon Dactylon ◽  
Themeda Triandra ◽  
Heteropogon Contortus ◽  
Degradation Rates ◽  
Ruminal Degradation ◽  
The Mean ◽  
Species Being

SUMMARYThe seasonal rate and extent of dry matter (DM) and neutral detergent fibre (NDF) degradation of the African sourveld grasses Alloteropsis semialata, Andropogon appendiculatus, Cynodon dactylon, Elionurus muticus, Eragrostis plana, Harpochloa falx, Heteropogon contortus, Hyparrhenia hirta, Microchloa caffra, Themeda triandra and Tristachya leucothrix in the rumen were measured using the nylon bag technique at the Döhne Agricultural Development Institute, South Africa, in 1993. The size of the soluble fraction (SF) was markedly different (P < 0·05) between species, being largest in A. semialata (22·6%) and smallest in E. plana (13%). Over all species, the mean SF was highest (P < 0·01) in spring (21·6%) and lowest in winter (11·8%). Species differed (P < 0·05) in the size of the potentially digestible fraction (PDF), with H. contortus and T. leucothrix having the largest (71%) and M. caffra the smallest (53%) PDF. Mean PDF declined (P < 0·01) from spring (77·3%) through to winter (55·8 %). The rate of DM degradation (kd) in the rumen also differed (P < 0·01) between species, with C. dactylon and A. semialata having the fastest (0·054) and E. plana and A. appendiculatus the slowest (0·039) degradation rates. Mean kd values were lower (P < 0·05) in winter (0·039) than in the other seasons (0·048).Neutral detergent soluble (NDS) content was highest in A. semialata (29%) and lowest in E. plana (21·5%). Species similarly varied in the amount of potentially digestible cell wall (PDCW), with E. plana having the highest (57%) and C. dactylon the lowest (45·1%) PDCW content. Mean PDCW content was highest in spring (59·5 %) and lowest in winter (44·6%). Cell wall degradation (kc) rates were fastest (0·04) in C. dactylon and slowest in M. caffra (0·03). Overall, kc declined from spring (0·039) through to winter (0·029). In general, A. semialata, T. triandra and H. hirta appeared to have the most favourable, and E. plana, A. appendiculatusand M. caffra the least favourable, ruminal degradation characteristics. These differences suggest that species composition is likely to have a major impact on potential animal production on these low quality grasslands.

Comparative responses of the Savanna grasses Cenchrus ciliaris and Themeda triandra to defoliation

Oecologia ◽  
1989 ◽  
Vol 79 (1) ◽  
pp. 45-52 ◽  
Author(s):  
K. C. Hodgkinson ◽  
M. M. Ludlow ◽  
J. J. Mott ◽  
Z. Baruch
Keyword(s):  
Cenchrus Ciliaris ◽  
Themeda Triandra

scholarly journals Rangeland Management and Ecological Adaptation Analysis Model for Astragalus curvirostris Boiss

Horticulturae ◽  
2021 ◽  
Vol 7 (4) ◽  
pp. 67
Author(s):  
Farhad Aghajanlou ◽  
Hamidreza Mirdavoudi ◽  
Mohammad Shojaee ◽  
Eileen Mac Sweeney ◽  
Andrea Mastinu ◽  
...  
Keyword(s):  
Environmental Gradient ◽  
Additive Model ◽  
Ecological Factors ◽  
Environmental Parameters ◽  
Rangeland Management ◽  
Systematic Sampling ◽  
Analysis Model ◽  
Seed Collection ◽  
Species Response ◽  
Ecological Requirements

The present study investigates the ecological requirements of Astragalus curvirostris Boiss, with emphasis on determining the ecological factors that affect the distribution of plant species, and the species’ response to changes in ecological factors using a Generalized Additive Model (GAM) in the Iranian Province of Zanjan from 2017 to 2019. Randomized-systematic sampling was used to collect vegetation data. Data analysis was performed using SPSS17 and CANOC4.5 software. The results showed that the growth and development of A. curvirostris change according to environmental factors linked to the composition of the soil and the variety of the other species present. This model is indicative of a competitive limitation along the environmental gradient. By understanding all environmental parameters, the necessary steps could be taken towards planning proper management programs, including rangeland grazing management and determining the proper moment for seed collection, which will result in the conservation, improvement, and restoration of rangelands.

scholarly journals Non-Native Eragrostis curvula Impacts Diversity of Pastures in South-Eastern Australia Even When Native Themeda triandra Remains Co-Dominant

Plants ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 596
Author(s):  
Corinne Schlierenzauer ◽  
Anita C. Risch ◽  
Martin Schütz ◽  
Jennifer Firn
Keyword(s):  
Species Composition ◽  
Plant Species ◽  
Plant Species Composition ◽  
Native Plant ◽  
Critical Function ◽  
Themeda Triandra ◽  
Eragrostis Curvula ◽  
Eastern Australia ◽  
Abundance And Diversity ◽  
Native Plant Diversity

Lowland grassy woodlands in Australia’s south-east face reductions in native plant diversity because of invasion by non-native plants. We compared the relative abundance and diversity of plant species among sites dominated by the native Kangaroo grass (KG) Themeda triandra with sites co-dominated by the non-native African lovegrass (ALG) Eragrostis curvula and KG. We found significant differences in plant species composition depending on the dominant species. Furthermore, our results revealed differences in several diversity parameters such as a lower species richness and forb diversity on sites co-dominated by ALG and KG. This was the case despite the functional similarity of both ALG and KG—both C4 perennial tussock grasses of a similar height. Therefore, our results highlight the critical function of the native KG in maintaining and enhancing the target plant species composition and diversity within these grassy woodlands. Herbivore grazing potentially impacts on the abundance of the dominant grass and forb species in various ways, but its impact likely differs depending on their evolutionary origin. Therefore, disentangling the role of individual herbivore groups (native-, non-native mammals, and invertebrates) on the plant community composition of the lowland grassy woodlands is essential to find appropriate grazing regimes for ALG management in these ecosystems.

scholarly journals Information available within the PRECIS data bank of the National Herbarium, Pretoria, with examples of uses to which it may be put

Bothalia ◽  
1981 ◽  
Vol 13 (3/4) ◽  
pp. 473-485 ◽  
Author(s):  
J. W Morris ◽  
R. Manders
Keyword(s):  
Information Storage And Retrieval ◽  
Data Bank ◽  
Flowering Phenology ◽  
Information Storage ◽  
Frequency Distributions ◽  
Themeda Triandra ◽  
Storage And Retrieval ◽  
Heteropogon Contortus ◽  
National Herbarium ◽  
History Of

The contents of the computerized information storage and retrieval system (PRECIS) of the National Herbarium, Pretoria (PRE) are described at length mainly by means of frequency histograms of descriptor codes. The frequency distributions found are discussed in the light of the history of the herbarium, the geography of the area and the habits of plant collectors. Two uses of PRECIS are illustrated by example. Firstly, the flowering phenology of  Eragrostis capensis, Themeda triandra and Heteropogon contortus is plotted and, secondly, the route followed by Dinter in South West Africa/Namibia from December 1933 until March 1935 is described. It is concluded that the system should be o f particular use in revisionary studies, regional floras and biogeographic research.

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