Range and distribution of Mimosa diplotricha in Nigeria and effects of fire on seed germination (original) (raw)
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2016
Invasive Alien Species (IAS) has been causing serious threats to biodiversity which need to be addressed and studied seriously. Mimosa diplotricha is an invasive plant in some parts of Africa and has recently come to Ethiopia, particularly, in Oromia Regional State, Jimma Zone. Therefore, the objective of this study was to assess the impacts, trends, mode of entry, status, distribution and management practices of Mimosa diplotricha in Jimma Zone, Southwest Ethiopia. Accordingly, an assessment was carried out in Jimma zone, Shebe-sombo, Kersa and Seka-chekorsa districts, in 72 randomly selected households in six different Kebeles (the smallest administrative unit in Ethiopia). Based on the interview and field observation, the level of Mimosa diplotricha invasion was very high and the plant was the most dominant IAS on road side in the study areas. Mimosa diplotricha was introduced to the study sites during road construction together with sand, stones and other construction materials....
Germination of four species of the genus Mimosa (leguminosae) in a semi-arid zone of Central Mexico
Journal of Arid Environments, 2003
Mimosa depauperata, M. lacerata, M. similis, and M. texana var. texana are dominant leguminous shrubs in the semi-arid region of Queretaro, in central Mexico. These species grow and reproduce under conditions of disturbance; they are occasionally browsed by goats and used for firewood. The effect of temperature on germination, the longevity of the seeds in the field, and the germination potential of seeds parasitized by insects of the family Bruchidae were tested. It was found that the seeds require scarification to germination. The optimum temperature for seed germination of M. similis, M. lacerata, and M. depauperata was between 201C and 351C and for M. texana var. texana between 301C and 351C. The species germinated just as well beneath the canopy as in open areas in the field. The seeds of each species are parasitized by bruchids of the genus Acanthocelides spp., and seed infestation necessarily had a detrimental effect. The seeds in the seed bank lose their longevity at a rate of 20-73% per year. As with other legumes, Mimosa seeds have a tough seed coat, which influences germination, longevity, and susceptibility to predation by bruchids. The results form this study contribute to an understanding of the phases of
Folia Geobotanica, 2019
Recruitment in savanna environments represents a high-risk step in a plant's life cycle. Dimorphandra mollis Benth (Fabaceae) is a savanna tree species which produces dry fruits holding coatimposed dormant seeds dispersed late in the dry season. We investigated fire effects on fruit dehiscence, seed dormancy breaking and seed viability, and also monitored seedling recruitment and survival for 44 months in a savanna area subjected to biennial controlled fires in central Brazil. Fruits were laid aboveground, and seeds were buried before and after an experimental fire set in August 1999. Fruits started to open after the experimental fire up to the following rainy season. Around one fourth of the seeds removed from these fruits were viable but required scarification to imbibe, indicating that fruits do not totally insulate seeds, and fire does not break seed dormancy. No seedling emerged from buried seeds during the first rainy season after the fire, but fourteen seedlings emerged during the second rainy season. Half of the seedlings died and the other half resprouted after a second experimental fire set during the third dry season. In the third rainy season, thirteen new seedlings emerged, but two died in the fourth dry season. We found that fire was a more determinant constraint to seedling survival than the dry season itself. After 44 months we recovered 27 viable seeds from those initially buried, suggesting that seeds of D. mollis have the potential to establish a persistent seed bank. As expected for savanna trees, we found that D. mollis seeds and seedlings may persist in environments periodically disturbed by fires.
Journal of Forestry Research, 2010
Prescribed fire is used in the Sudanian savanna-woodland of West Africa as a forest management tool. An experiment was carried out to assess the effects of season of burning, and different vertical probe positions on maximum fire temperature and temperature residence time above 60°C which is considered lethal for plant tissues. Seasons of burning considered were: an early season fire set at the beginning of the dry season (beginning of December), mid-season fire set at the peak of the dry season (mid-January), and a late season fire at the end of the dry season (end of March). The effects of these fires on the germination of buried seeds of three socio-economically valuable tree species were also examined. Results indicated significant differences in maximum fire temperature and residence time with respect to season of burning and vertical probe position (p < 0.001). The highest and longest lasting temperatures were observed at 20 cm above ground during early fire and at the soil surface during mid-season and late fires. This, in turn, affected germination responses of seeds buried at different soil depths. Implications of these findings in the current management practices are discussed.
Rupestrian grasslands over ironstone outcrop, locally named canga, are montane ecosystems with restricted distribution known to harbor an unusually a large number of endemic plant species. These communities are highly threatened due to their high sensitivity to habitat conversions and extreme low resilience derived from anthropogenic pressure. Ecological restoration attempts on degraded rupestrian grassland areas have not yet been successful. Mimosa calodendron is an endemic canga shrub thought to play a facilitator role and, therefore, may enhance seedling recruitment in degraded areas. Since dormancy and slow germination are key factors of the biology of seeds and may hamper their use in ecological restoration, this study aimed to investigate the environmental control of seed dormancy and germination of M. calodendron seeds. We tested the effect of mechanical scarification, light and different incubation temperatures on seed germination. The effect of scarification on water uptake by seeds was also measured. M. calodendron seeds have physical dormancy and scarification was an effective treatment to promote high and rapid germination. Heat treatment also increased germination percentage of non-scarified seeds, but was less efficient than scarification. Once water uptake occurred, germination took place under a broad thermal gradient, regardless of light condition. Therefore, the germination profile of M. calodendron seems to be suitable for uncomplicated use in restoration projects, requiring only a pretreatment for dormancy release.
Grass and Forage …, 2006
The aim of the study was to evaluate the potential impact of grazing on the control of Mimosa pudica, a ligneous weed species that invades grasslands in French Guiana. Three experiments were conducted in a glasshouse to test the potential impact of: (i) shading by testing different Photsynthetically Active Radiation (PAR) fluxes on seedlings and (ii) cutting of juveniles, at three stages of development, on their survival, flowering rate and nutritive value as measured by the mass:length ratio of stems and by branching processes. A significant mortality rate (0AE20) was obtained only for seedlings at the cotyledon stage when the PAR flux was reduced proportionately by 0AE83. Shading reduced both flowering rate and mass:length ratio of stems. For seedlings at the cotyledon stage, the flowering rate decreased from 0AE85 for the control to zero for the low light treatment (0AE13 of PAR flux of the control treatment). The mass:length ratio of stems of seedlings in the low light treatment was reduced to 0AE20 of that of control seedlings, at the fifth-leaf stage. Cutting treatment had no effect on mortality of juvenile plants whatever the size of the juvenile plant. The proportion of juvenile plants flowering was high for all cutting treatments. It is suggested that regular, but not continuous grazing, could maintain a dense sward to limit recruitment by seedling establishment and seed production, and maintain branched and juvenile plants with a high-nutritive value at the seedling stage.
Flora, 2010
Smoke generated by burning of plant materials has widely been recognized as a germination cue for some species from both fire prone and fire-free ecosystems. It is an important factor for the understanding of vegetation dynamics and could have potential use for ecological management and rehabilitation of disturbed areas. Individual species, however, seem to have a specific requirement for the type and dosage of smoke treatments. In the present study, six different concentrations of smoke solution were tested on 13 herbaceous species by soaking the seeds for 24 h. The germination of a forb species, Borreria scabra, was significantly stimulated (p o0.05) by the smoke treatment while that of the annual grass species, Euclasta condylotricha, was significantly inhibited (p o 0.05) by 100% smoke solution treatment. Contrary to our expectation that another fire-related cue, heat shock, would break the physical dormancy of the species tested, it was not promotive. For non-dormant seeds of B. scabra and Borreria radiata, high temperatures were lethal while low temperature induced physiological dormancy that was overcome in the former species within 30 days of the germination trial. For some species, responses to smoke did not corroborate with the field-observed response to fire, making ecological interpretation challenging. For responsive species, the smoke treatment could be a simple approach for promoting their re-establishment in areas where it is needed. More investigations are needed to assess the spread of response to smoke.
We investigated the effect of fire on understory plant species density in University of Port Harcourt Biodiversity Centre four months after fire incident. This is aimed at the knowing the ability of the forest to recover from bush fire. Twenty four (4 m x 4 m) plots (14 burnt and 10 un-burnt or control) were mapped out. The plant seedlings in these plots were sampled, identified and enumerated. The diversity, relative abundance, relative frequency, relative diversity, species importance value, family importance value and seedling density were determined. A total of 53 plant species belonging to 35 families were identified in the area studied. The un-burnt (control) plots had 11 species with 9 plant families while the burnt (impacted) plots had 52 species and 33 families. Fabaceae and Rubiaceae families had the maximum number of species in the control plots, while Asteraceae, Poaceae and Fabaceae families had the maximum number of species in the burnt plots. Based on the habit of the plant species identified, there is difference in the number of plant species, seedling density, relative abundance, species density and importance values (dominance)
Plant Species Biology, 2010
The Empress tree (Paulownia tomentosa Steud.) is a fast growing deciduous tree originating from East Asia. It is grown as an ornamental plant, but can also be used as industrial wood. However, in some parts of North America, this species is considered invasive, with high impact on autochthonous populations. We have investigated whether post-fire expansion of this species can be explained at the germination level by analyzing the interaction between physical (light and temperature) and chemical (smoke and nitrogenous compounds) fire-related cues in the regulation of P. tomentosa germination. Light is the key environmental signal in the induction of germination of positively photoblastic P. tomentosa seeds. Smoke, applied in the form of extract (liquid smoke [LS]), stimulates light-induced germination if applied during imbibition, or shortly after the inductive irradiation. This stimulatory effect of LS can be effectively prevented by far-red light, suggesting that the mechanism of smoke action is phytochrome related. The LS had no effect on the germination percentage when applied during the phase of radicle protrusion. However, LS reduced radicle elongation and slowed its protrusion. The LS had no effect on the optimal temperature range of germination (23–27°C). The combined action of LS and KNO3 in light-induced germination was more effective then when each chemical was applied separately. It can be concluded that all tested components of fire, except elevated temperature, operate to stimulate germination of P. tomentosa seeds, suggesting that the post-fire invasive potential of this species can, at least in part, be explained at the germination level.