The Schedonorus-Lolium complex of the subtribe Loliinae (Poaceae) includes several economically important forage and turf grasses. This complex encompasses Lolium Linnaeus, 1753, Festuca ...Linnaeus, 1753 subgenus Schedonorus (P. Beauvois, 1824) Petermann, 1849 and Micropyropsis Romero Zarco et Cabezudo, 1983. New FISH results of 5S and 18S-26S rDNA sequences are presented for three species and the results are interpreted in a review of distribution patterns of 5S and 18S-26S rDNA sequences among other species in the complex. Micropyropsis tuberosa Romero Zarco et Cabezudo, 1983 (2n = 2x = 14) displayed a distribution pattern of rDNA sequences identical to that of F. pratensis Hudson, 1762, supporting a close phylogenetic relationship at the bottom of the phylogenetic tree. "Lolium multiflorum" Lamarck, 1779 accessions sourced from Morocco showed a different pattern from European L. multiflorum and could be a unique and previously uncharacterised taxon. North African Festuca simensis Hochstetter ex A. Richard, 1851 had a marker pattern consistent with allotetraploidy and uniparental loss of one 18S-26S rDNA locus. This allotetraploid has previously been suggested to have originated from a hybrid with Festuca glaucescens (Festuca arundinacea var. glaucescens Boissier, 1844). However, the distribution patterns of the two rDNA sequences in this allotetraploid do not align with F. glaucescens, suggesting that its origin from this species is unlikely. Furthermore, comparisons with other higher alloploids in the complex indicate that F. simensis was a potential donor of two sub-genomes of allohexaploid Festuca gigantea (Linnaeus) Villars, 1787. In the overall complex, the proximal locations of both rDNA markers were conserved among the diploid species. Two types of synteny of the two markers could, to a considerable extent, distinguish allo- and autogamous Lolium species. The ancestral parentage of the three Festuca allotetraploids has not yet been determined, but all three appear to have been sub-genome donors to the higher allopolypoids of sub-genus Schedonorus. Terminal locations of both the markers were absent from the diploids but were very frequently observed in the polyploids. Keywords: Festuca , FISH, karyotype evolution, Lolium , rDNA locus evolution, species diversification
The article considers the results of research on the biological productivity of the ecosystems of the Republic of Tuva, in particular, the dynamics of phytomass reserves, pure primary products were ...carried out in various landscapes of Tuva from 1996 to 2021. It was revealed that the landscape zones of Tuva differ in area, climate and biome structure, where the main producers are grass ecosystems that form 48% of the NPP, the contribution of forests reaches 46%, agrocenoses 1.5%, i.e. more than 90% of products are created in almost equal quantities by forest and grass biomes.
Invasive species can change selective pressures on native plants by altering biotic and abiotic conditions in invaded habitats. Although invasions can lead to native species extirpation, they may ...also induce rapid evolutionary changes in remnant native plants. We investigated whether adult plants of five native perennial grasses exhibited trait shifts consistent with evolution in response to invasion by the introduced annual grass Bromus tectorum L. (cheatgrass), and asked how much variation there was among species and populations in the ability to grow successfully with the invader. Three hundred and twenty adult plants were collected from invaded and uninvaded communities from four locations near Reno, Nevada, USA. Each plant was divided in two and transplanted into the greenhouse. One clone was grown with B. tectorum while the other was grown alone, and we measured tolerance (ability to maintain size) and the ability to reduce size of B. tectorum for each plant. Plants from invaded populations consistently had earlier phenology than those from uninvaded populations, and in two out of four sites, invaded populations were more tolerant of B. tectorum competition than uninvaded populations. Poa secunda and one population of E. multisetus had the strongest suppressive effect on B. tectorum, and these two species were the only ones that flowered in competition with B. tectorum. Our study indicates that response to B. tectorum is a function of both location and species identity, with some, but not all, populations of native grasses showing trait shifts consistent with evolution in response to B. tectorum invasion within the Great Basin.
Elevated atmospheric CO.sub.2 concentration increases the performance of invasive plants relative to natives when grown in monoculture, but it is unclear how that will affect the relative competitive ...abilities per se of invasive and native grasses grown together. We tested competitive outcomes for four native and four invasive perennial C3 and C4 grasses under ambient (390 ppm) and elevated (700 or 1000 ppm) CO.sub.2 concentrations in the greenhouse with non-limiting water and nutrients. We predicted that elevated CO.sub.2 would increase the competitive suppression of native grasses by invasive grasses. To test this, we determined the relative interaction intensity of biomass allocation for natives grown alone vs. those grown in native-invasive species pairs. We also measured photosynthetic traits that contribute to plant invasiveness and may be affected by elevated CO.sub.2 concentrations for species pairs in mixture to determine native-invasive relative performance. We found no effect of CO.sub.2 for the aboveground biomass and tiller production measures of interaction intensity or for relative performance for most of the measured photosynthetic traits. In competition, the invaders nearly always outperform natives in biomass and tiller production, regardless of CO.sub.2 level. The results suggest that increasing CO.sub.2 concentration alone has little effect on grass competitive outcomes under controlled conditions.
Non‐native, invasive grasses have been linked to altered grass‐fire cycles worldwide. Although a few studies have quantified resulting changes in fire activity at local scales, and many have ...speculated about larger scales, regional alterations to fire regimes remain poorly documented. We assessed the influence of large‐scale Bromus tectorum (hereafter cheatgrass) invasion on fire size, duration, spread rate, and interannual variability in comparison to other prominent land cover classes across the Great Basin, USA. We compared regional land cover maps to burned area measured using the Moderate Resolution Imaging Spectroradiometer (MODIS) for 2000–2009 and to fire extents recorded by the USGS registry of fires from 1980 to 2009. Cheatgrass dominates at least 6% of the central Great Basin (650 000 km²). MODIS records show that 13% of these cheatgrass‐dominated lands burned, resulting in a fire return interval of 78 years for any given location within cheatgrass. This proportion was more than double the amount burned across all other vegetation types (range: 0.5–6% burned). During the 1990s, this difference was even more extreme, with cheatgrass burning nearly four times more frequently than any native vegetation type (16% of cheatgrass burned compared to 1–5% of native vegetation). Cheatgrass was also disproportionately represented in the largest fires, comprising 24% of the land area of the 50 largest fires recorded by MODIS during the 2000s. Furthermore, multi‐date fires that burned across multiple vegetation types were significantly more likely to have started in cheatgrass. Finally, cheatgrass fires showed a strong interannual response to wet years, a trend only weakly observed in native vegetation types. These results demonstrate that cheatgrass invasion has substantially altered the regional fire regime. Although this result has been suspected by managers for decades, this study is the first to document recent cheatgrass‐driven fire regimes at a regional scale.
The super(137)Cs and super(40)K activities and transfer factors from soil to vegetables, grass, and milk from villages located around Tarapur Atomic Power Station (TAPS) were determined using ...high-resolution gamma spectrometry. A total of 32 soil, 21 vegetable, 23 dry paddy grass, and 23 milk samples were collected from 23 different agricultural farms from various villages around TAPS to determine transfer factors for natural environment. The mean concentration values for super(137)Cs and super(40)K in soil, grass, and milk were 2.39+/-0.86Bqkg super(-1), 0.31+/-0.23Bqkg super(-1), and 12.4+/-5.7mBqL super(-1) and 179+/-31Bqkg super(-1), 412+/-138Bqkg super(-1), and 37.6+/-9.3BqL super(-1), respectively, for soil-grass-milk pathway. In the soil-vegetation pathway, the mean concentrations values for super(137)Cs and super(40)K were 2.15+/-1.04Bqkg super(-1), 16.5+/-7.5mBqkg super(-1), and 185+/-24, 89+/-50Bqkg super(-1), respectively. The evaluated mean transfer factors from soil-grass, grass-milk, and soil-vegetation for super(137)Cs were 0.14, 0.0044, and 0.0073 and that of super(40)K were 2.42, 0.0053, and 0.49, respectively. Only 15 out of total 44 milk and vegetable samples were detected positive for super(137)Cs, indicating a very low level of bioavailability.
The influence of rotational grazing intervals on morphogenesis of five native grasses from Rio Grande do Sul state (RS) central region, grouped according to a functional typology, was evaluated ...during spring and summer seasons. Leaf appearance rate, leaf elongation rate and leaf senescence rate (LAR/LER/LSR) phyllochron, leaf lifespan and leaf elongation duration (LLP/LED) were evaluated on Axonopus affinis, Aristida laevis, Andropogon lateralis, Paspalum notatum and Paspalum plicatulum, under two rotational grazing intervals, defined by thermal time (°C'), 375 and 750 degree-day, during 2010 spring and 2010/2011 summer. There was no significant difference between grazing intervals, but there was among species and between seasons. Paspalum notatum highlights significant adjustments to grazing. Axonopus affinis and P. notatum presented the largest LAR and smallest LLP, while A. lateralis presented morphogenic characteristics which contradict literature. Spring and summer was characterized as the growing and flowering periods, respectively. Grazing showed influence on forage morphogenesis, however, the evaluated grazing intervals had no effect on species development and the seasonal influence define native grasses development. Key words: grazing, leaf elongation duration, management, morphogenesis. O trabalho objetivou determinar a influencia de intervalos de pastoreio rotativo sobre a morfogenese de cinco gramineas nativas da regiao central do Rio Grande do Sul (RS), agrupadas segundo uma tipologia funcional, nas estacoes de primavera e verao. Foram avaliadas taxa de aparecimento, elongacao e senescencia foliares (TAF/TEF/TSF), filocrono e duracao de vida e de elongacao foliares (DVF/DEF) em Axonopus affinis, Aristida laevis, Andropogon lateralis, Paspalum notatum e Paspalum plicatulum, sob dois intervalos de pastoreio rotativo, definidos por somas termicas (0C'), 375 e 750 graus-dia, na primavera 2010 e verao 2010/20U. Nao houve diferenca significativa entre intervalos de pastoreio, mas houve entre especies e entre estacoes. Paspalum notatum se destacou por apresentar adaptacoes bem marcadas ao pastejo. Axonopus affinis e P notatum foram as especies com maiores TAF e menores DVF, ja A. lateralis apresentou caracteristicas morfogenicas que contradizem a literatura. Quanto as estacoes, primavera se caracterizou como a estacao de crescimento, e verao, como o inicio do florescimento. Pastejo afeta a morfogenese de forrageiras, no entanto, os intervalos de pastoreio usados nao tem efeito sobre o desenvolvimento das especies e a influencia estacional e marcante no desenvolvimento dessas gramineas. Palavras-chave: duracao da expansao foliar, manejo, morfogenese, pastejo.
The influence of rotational grazing intervals on morphogenesis of five native grasses from Rio Grande do Sul state (RS) central region, grouped according to a functional typology, was evaluated ...during spring and summer seasons. Leaf appearance rate, leaf elongation rate and leaf senescence rate (LAR/LER/LSR) phyllochron, leaf lifespan and leaf elongation duration (LLP/LED) were evaluated on Axonopus affinis, Aristida laevis, Andropogon lateralis, Paspalum notatum and Paspalum plicatulum, under two rotational grazing intervals, defined by thermal time (°C'), 375 and 750 degree-day, during 2010 spring and 2010/2011 summer. There was no significant difference between grazing intervals, but there was among species and between seasons. Paspalum notatum highlights significant adjustments to grazing. Axonopus affinis and P. notatum presented the largest LAR and smallest LLP, while A. lateralis presented morphogenic characteristics which contradict literature. Spring and summer was characterized as the growing and flowering periods, respectively. Grazing showed influence on forage morphogenesis, however, the evaluated grazing intervals had no effect on species development and the seasonal influence define native grasses development.
Changes in climate and land use that interact synergistically to increase fire frequencies and intensities in tropical regions are predicted to drive forests to new grass-dominated stable states. To ...reveal the mechanisms for such a transition, we established 50 ha plots in a transitional forest in the southwestern Brazilian Amazon to different fire treatments (unburned, burned annually (B1yr) or at 3-year intervals (B3yr)). Over an 8-year period since the commencement of these treatments, we documented: (i) the annual rate of pasture and native grass invasion in response to increasing fire frequency; (ii) the establishment of Brachiaria decumbens (an African C4 grass) as a function of decreasing canopy cover and (iii) the effects of grass fine fuel on fire intensity. Grasses invaded approximately 200 m from the edge into the interiors of burned plots (B1yr: 4.31 ha; B3yr: 4.96 ha) but invaded less than 10 m into the unburned plot (0.33 ha). The probability of B. decumbens establishment increased with seed availability and decreased with leaf area index. Fine fuel loads along the forest edge were more than three times higher in grass-dominated areas, which resulted in especially intense fires. Our results indicate that synergies between fires and invasive C4 grasses jeopardize the future of tropical forests.
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