nomes no trilho de navegação
Nile region.
Native to tropical Africa, introduced in the tropics as a fodder plant.
Molasses grass percent cover
on unburned, once- and twice-burned sites near Kipuka Nene,
Hawai`i Volcanoes National Park [11,21]
Fire characteristics, and molasses grass cover on burned
and unburned sites in Hawai`i Volcanoes National
Park [13,45]
Elevation (m)
Month of fire Area burned (ha) Fire intensity Years since fireThis description provides characteristics that may be relevant to fire ecology and is not meant for identification. Keys for identification are available (e.g., [2,50]).
Aboveground description: Molasses grass is a strong-smelling [50], perennial grass [2,38,50] that may be as short as 20 inches (50cm) but is typically 30 to 60 inches (80-150 cm) tall [2]. It produces long, slender stems that layer on top of one another, forming thick mats [9,31,32,33,34,38,46] that can be from 4 to 5 feet (1.2-1.5 m) deep [11,12]. Molasses grass has a sprawling growth form and can "climb" over shrubs much like a vine. It grows upward and outward, using other species for support. Molasses grass can carpet large areas of ground completely [11], which can reduce seedling establishment and growth of other plants [9,34,38,50]. Molasses grass leaves range from 1.4 to 9.8 inches (3.5-25 cm) long [2,50], and panicles are 3 to 8 inches (7-20 cm) long and 0.4 to 3.7 inches (1-9.5 cm) wide [2]. Molasses grass spikelets are 1.5 to 2.4 mm long [2,50]. At Hawai`i Volcanoes National Park (on a site with 17% molasses grass cover), molasses grass averaged 375.2 flowering shoots/m² [12]. The fruit of molasses grass is a caryopsis that is often undeveloped [50] and is from 0.9 to 1.2 mm long and 0.3-0.4 mm wide [2].
Belowground description: Molasses grass plants usually root at the lower stem nodes [2]. At a site dominated by molasses grass in Hawai`i Volcanoes National Park, molasses grass root biomass ranged from 176.9 to 198.2 g/m² [12].
Molasses grass occurs in Hawaii [50], in Florida [53,54,55]—especially along the lower eastern coast [15]—and Puerto Rico [7]. In Hawaii, molasses grass occurs on all the main islands except Ni`ihau [50]. Grass Manual on the Web provides a distributional map of molasses grass.
Molasses grass is native to Africa [2,34,50,54,55], where it occurs in 2 disjunct populations in tropical areas [34]. The western population occurs in an arc from central Angola to Cameroon, while the eastern population occurs on the lower slopes and adjacent areas of the Ruwenzori Range and Mount Kenya [34]. Molasses grass established in Brazil around 1812, where it thrives on disturbed, abandoned coffee lands of the ParaÃba Valley [34].
Molasses grass was introduced to Hawaii in the early 1900s for cattle forage [9]. It was first collected on Lana`i Island in 1914 [50]. In the 1920s it was introduced to Moloka`i Island [1]. By the 1940s it was present in Hawai`i Volcanoes National Park but was mainly restricted to roadways [45,46], where it was probably controlled by feral goat grazing [46]. Molasses grass spread in Hawai`i Volcanoes National Park began in the 1970s, facilitated by the removal of feral goats [44].
Fire adaptations: Molasses grass is adapted to regenerate vegetatively and by seed after fire. D'Antonio and others [11] state that low- to high-severity fires can cause complete mortality in molasses grass, but that plants establish from seeds that can survive low-severity fires in the soil seed bank [11]. Smith [38] claims that dense molasses grass mats are only partly consumed by fire. Following fire, molasses grass regeneration from the "remaining portions" is rapid and colony expansion into adjacent burned areas generally follows [38]. In Hawai`i Volcanoes National Park, Tunison and others [45] studied burned sites where molasses grass regenerated after fire from basal meristems and seeds. At postfire month 20, molasses grass regeneration via basal meristems on burned sites was nearly twice that on unburned sites. Molasses grass regeneration via seeds peaked at postfire month 4 [45].
Fuels: Molasses grass is highly flammable [21,22,30], quick burning [22], and promotes fire [46] by increasing vegetation horizontal continuity in invaded communities [8]. Molasses grass leaves are coated with a resinous material and may have a high heat content [46]. Molasses grass stands maintain a high dead:live biomass ratio throughout the year (80-90%) and can carry fire at relative humidities of 85% to 95% and fuel moistures of 20% to 25% [21]. In Hawai`i Volcanoes National Park, molasses grass fuels have been measured as high as 25,370 kg/ha [46]. Another study in Hawai`i Volcanoes National Park compared fuel loads in different vegetation types. Total fuel biomass was greater in an unburned woodland (1,967.4 g/m²) than in woodlands converted to nonnative grasslands (1,427.5 g/m²) on sites burned 24 and 7 years previously. However, fine fuel loads (live + dead) were higher in converted grasslands (996.2 g/m²) than in unburned woodlands (613.0 g/m²) [16]. Where molasses grass is dominant or codominant in Hawaii Volcanoes National Park, fire impacts on native plants are "always greater" than where it is absent [13].
The fine fuel characteristics of a pure molasses grass stand were measured in 1975 at Kuaokala Forest Reserve near Ka`ena, Hawaii [17]. The median annual rainfall in the reserve for a 28-year period was 32 inches (810 mm). In 1975, total precipitation was 30 inches (750 mm).
Molasses grass fine fuel characteristics at Kuaokala Forest Reserve, Hawaii [17]
Characteristic Minimum Maximum Mean Depth of fuel (inches) Stalk 0 47 26.32 Leaf 0 46 26.88 Surface area-to-volume (1/foot) Stalk 471 1,200 676 Leaf 3,000 8,000 4,536 Mean fuel weight for all subplots (lb/ft²) 0.458 3.481 1.721In the cerrado of Brazil, where molasses grass is common at the edge of gallery forests, total living and dead leaf area index is 38% greater on sites with molasses grass than on sites without it. Greater fuel loads in sites with molasses grass increase fire intensity [19]. Computer models of the Reserva Ecológica do Roncador, Brazil, suggest that when dead fuel moisture in molasses grass-dominated stands is less than 15%, fires can move rapidly even at low wind speeds. At 16% dead fuel moisture and wind speeds of 6 miles/hour (10 km/hour), flame heights in molasses grass stands were predicted to be 22 feet (6.6 m). Fire temperatures in molasses grass stands in late August were predicted to peak at 1,000 to 1,843 °F (800-1,006 °C). Flame heights and fire intensities in molasses grass stands would likely kill many trees in the Brazilian reserve, a phenomenon that does not naturally occur in vegetation fires there. Even during periods of "low" burning conditions in the reserve, computer models suggest fires in molasses grass stands could spread rapidly. The effect of molasses grass on fire intensity in the reserve could be "devastating". Fuel characteristics on sites dominated by molasses grass and sites dominated by native vegetation without molasses grass are presented below [30].
Fuel characteristics modeled in the Reserva Ecológica do Roncador, Brazil, in nonnative and native sites [30]
Characteristic Vegetation type Molasses grass-dominated sites Native vegetation sites (range) Live herbaceous fuel (t/ha) 2.1 0.1-3.0 Live herbaceous fuel moisture (%) 107 107-200 Fuel depth (m) 0.7 0.3-0.5 Surface area:volume of live herbaceous fuel (/cm) 39 39-42 Heat content of dead fuel (KJ/kg) 23,300 17,200-19,500 Heat content of live fuel (KJ/kg) 18,600 16,300-17,000FIRE REGIMES: Research from Hawaii shows [8,14,37,40] and computer models in Brazil [30] suggest that molasses grass can cause an increase in both fire frequency and size.
Hawaii: The size and frequency of fires have increased in some plant communities in Hawaii following the establishment and spread of molasses grass and other nonnative grasses [1,8,14,37,40]. Fires fueled by broomsedge bluestem (Andropogon virginicus), molasses grass, buffelgrass (Pennisetum ciliare), fountain grass, and bush beardgrass (Schizachyrium condensatum) largely account for the dramatic increase in fire size and frequency in seasonal submontane and eastern coastal lowland zones in the last 25 years [13,26,37,40,45,46]. For example, prior to nonnative grass invasions, `ōhi`a woodlands consisted of open stands of discontinuous fine fuels. Now, nonnative grasses constitute over 30% of the understory biomass and 60% to 80% of the understory cover in Hawai`i Volcanoes National Park's `ōhi`a woodlands, forming a continuous source of fine fuel [10].
Flammable, fire-dependent, or fire-maintained plant species do not occur in most native, undisturbed plant communities in Hawaii, and therefore fires were assumed to be of little ecological significance [40]. While presettlement FIRE REGIMES are difficult to reconstruct in Hawaii [40], historical fires were probably very small and localized [39]. The first nonnative grass-fueled fire was reported in Hawaii in 1968 [40]. Fire frequency and fire size have increased markedly in Hawai`i Volcanoes National Park since 1968. From 1920 to 1967, 27 fires averaging 10 acres (4 ha) were recorded. From 1968 to approximately 1991, 58 fires burned an average of 507 acres (205 ha) each [16]. Some fires may be related to increased volcanic activity from 1983 to 1992. However, an increase in fine fuels following the removal of feral goats in the 1970s is a more likely cause [16,40,44]. Since the spread of fire-prone grasses in Hawai`i Volcanoes National Park during the 1960s and 1970s, fire frequency has increased 3-fold and fire size over 60-fold [46].
Most native shrubs in Hawaii are negatively impacted by fire, and their cover and dominance are reduced in the postfire environment while nonnative grass cover tends to increase [38,40]. Nonnative grasses such as molasses grass can lead to a grass/fire cycle in Hawaii [21,26,45,46]. A grass/fire cycle threatens to turn native Hawaiian woodlands and tropical forests into nonnative grass savannas or monotypic grasslands [40,46,48]
Brazil: In the 3,200 acre (1,300 ha) Reserva Ecológica do Roncador, Brazil, molasses grass has increased the potential for fire [30]. Molasses grass increases the intensity of fires at gallery forest edges in the cerrado, where native trees are fire sensitive [19].
Australia: Near the foothills of Cairns, Australia, molasses grass is a "rapid colonizer" on severely burned sites. Where it grows on steep slopes it can causes "hot, potentially damaging" fires [42].
Find further fire regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find FIRE REGIMES".
Prescribed fire as a control agent for molasses grass: Prescribed fire is not recommend as a management tool for molasses grass in Hawaii, because fires are harmful to many native ecosystems in Hawaii. Nonnative species, particularly grasses, establish on burned sites more rapidly than native species, dominate many sites after fire, and fuel further fires, leading to a grass/fire cycle [26,40,45].
Potential for postfire establishment and spread: The high potential for postfire establishment and spread of molasses grass should be noted. If fire occurs in or near a community where molasses grass occurs, establishment and spread of molasses grass are probable. Tunison and others [45] suggest that fire suppression and prevention should be emphasized in the submontane seasonal zone of Hawai`i Volcanoes National Park to reduce negative effects on native vegetation and the continued spread of nonnative grasses. Further, sites severely degraded by fire should be revegetated with native, fire-tolerant plant species in an effort to reduce nonnative grasses [45].
In Hawaii, molasses grass occurs in dry and mesic lowland communities (see Habitat Types And Plant Communities) [49] and along roadsides [52]. In Florida, molasses grass occurs on dry, disturbed sites [53,54,55].
Climate: In Hawaii, where the climate is warm-tropical, molasses grass occurs where the mean annual air temperature is 76 °F (23 °C) and annual rainfall ranges from 60 to 80 inches (1,500-2,000 mm). There is a pronounced dry period during the summer [13].
Elevation: In Hawaii, molasses grass occurs from sea level to 4,900 feet (0-1,500 m) [38,50,52].
Soils: In Hawai`i Volcanoes National Park, molasses grass grows on ash-derived soils over pahoehoe lava [11]. Parsons [34] says that molasses grass thrives best on thin soils.
Impacts: Molasses grass negatively impacts native plant species and FIRE REGIMES where it occurs in Hawaii and South America. It is considered one of the 3 most invasive grasses in the Hawaiian seasonal submontane zone [21] and one of the 10 most invasive species in Hawaii [39].
Impacts on native Hawaiian plants: In Hawaii, molasses grass forms dense mats that can interfere with establishment of many native species [19,38,49]. Molasses grass has a sprawling growth form and can "climb" over shrubs much like a vine. It grows upward and outward, using other species for support. Molasses grass can carpet large areas of ground completely [11], which can "snuff" out other plants [9,34,38]. Molasses grass has become abundant in Hawai`i Volcanoes National Park since the early 1970s [29,38]. It was first introduced on the lower leeward slopes of Moloka`i Island in the 1920s, and, as of 1996, occurred in large monospecific stands that extended beyond the initial pastures. It has also spread into upper elevation (2,600 to 3,300 feet (800-1,000 m)), moist shrublands, forming many large monospecific stands and mixed grass-shrub mosaics ranging in size from 0.2 to 200 acres (0.1-100 ha) [1]. In coastal areas, molasses grass is replacing native pili grass on some sites [49].
Molasses grass is considered a major threat to 10 taxa on 4 Hawaiian Islands. In the Waianae Mountains of Oahu, 3 populations of Hawaii lady's nightcap (Bonamia menziesii), 2 populations of sprawling schiedea (Schiedea hookeri), and 1 population each of Kāmanomano (Cenchrus agrimonioides), Kauai spurge (Euphorbia haeleeleana), and ale (Plantago princeps var. princeps) are immediately threatened by molasses grass. On Moloka`i, at least 1 population each of erect island spleenwort (Diellia erecta), ale (P. princeps var. laxifolia), and woodland ma`oloa (Neraudia sericea), and all populations of Oahu cowpea (Vigna o-wahuensis) are negatively affected by molasses grass. Molasses grass is quickly spreading throughout the dry regions of West Maui, threatening 2 populations of erect island spleenwort. On Hawaii Island, a rare population of `ohai in Hawai`i Volcanoes National Park is located in an area invaded by molasses grass [48].
Postfire impacts on native Hawaiian plants: Molasses grass and other nonnative grasses have fueled large, frequent fires in Hawaii over the past 25 to 30 years [1,8,14,26,37,40]. Molasses grass-fueled fires can lead to the decline or extirpation of native species [11,13,21]. The negative impact of molasses grass-fueled fires on native species in Hawai`i Volcanoes National Park is likely due to one or more of the following: 1) high prefire biomass, 2) vigorous postfire regeneration, 3) postfire morphology that inhibits native species, 4) altered fire characteristics associated with leaf chemistry or molasses grass fuel characteristics [13].
Nonnative grasses have extensively invaded areas of Hawai`i Volcanoes National Park. Following fires, native shrub cover is reduced and the reduction can last for at least 20 years or more, even in the absence of additional fire [11,16]. On the southwest flank of Kilauea Volcano, Hughes and Vitousek [20] studied the effect that postfire establishment of bush beardgrass and molasses grass has on the native shrubs pukiawe, `a`ali`i, `ūlei (Osteomeles anthyllidifolia), and Hawaii false ohelo (Wikstroemia phillyreifolia). The researchers found that densities of native shrubs following fires were significantly lower in burned sites than unburned sites (P<0.05). Only `a`ali`i is able to establish via seed immediately after fire. The rapid establishment and persistence of nonnative grasses following fire negatively impacts the persistence of native shrubs [20].
At Hawai`i Volcanoes National Park, fires in 1970 and 1987 led to dominance by molasses grass and the introduced bush beardgrass. Prior to fires, the overstory was dominated by the native tree `ōhi`a and the understory by the shrubs pukiawe, `a`ali`i, and Hawaii hawthorn [12]. In burned areas of Hawai1i Volcanoes National Park, molasses grass and bush beardgrass are the dominant species. With the exception of `a`ali`i, native shrubs are largely lacking. Molasses grass cover increased from 7.2% in unburned Hawaiian woodlands to 79.3% in twice-burned sites, with biomass increase from less than 10 g/m² to greater than 700 g/m² [11].
South America: In the Cerrado of Brazil, molasses grass is known to cause "large" reductions in the establishment of the gallery forest pioneer cecropia (Cecropia pachystachya) tree and other trees and shrubs [19]. In the Reserva Ecológica do Roncador, Brazil, molasses grass may reduce plant biodiversity [30]. Molasses grass is invading grasslands of the Venezuelan savannas and displacing native grasses [3,4]. Molasses grass is able to displace the native grass crinkle-awn (Trachypogon plumosus) in areas with "favorable" water and soil nutrient supplies, but crinkle-awn resists invasion by molasses grass in drier, infertile sites [4].
Control: At the time of this writing (2008), there was no information on control of molasses grass. In a 1998 publication, it is stated that molasses grass has never been targeted for biological control [48].
OTHER MANAGEMENT CONSIDERATIONS:
Global climate change: Elevated CO2 levels cause molasses grass to grow at a greater rate than the native South American savanna grass crinkle-awn [5]. In a controlled study, elevated CO2 caused molasses grass to produce significantly (P<0.05) more total biomass and leaf area than crinkle awn, and to be significantly (P=0.02) taller and grow twice as fast as the native grass [5].
The literature does not describe in detail the importance of molasses grass to wildlife and livestock. It is considered a "good" forage grass for livestock [38] and was grazed by feral goats before their removal from Hawai`i Volcanoes National Park [31,33,44].
Palatability/nutritional value: No information is available on this topic.
Cover value: At the time of this writing (2008), there was no information on the cover value of molasses grass. However, molasses grass grows in dense stands and can reach heights from 30 to 60 inches (80-150 cm) [2], so it likely provides cover for some animals.
No information was found in the available literature that described habitat
types or plant communities in areas of Africa where molasses grass is native. In
Peru, molasses grass occurs in bluestem (Andropogon lanatum, A. leucostachyus)
savannas [36]. Molasses grass occurs in Florida [53,54,55]. Information regarding plant communities in which it occurs
in Florida is sparse. It has been collected in pastures [43] and in south Florida slash pine
(Pinus elliottii var. densa) rocklands in Miami-Dade County [15].
Hawaii: Molasses grass is common in
primarily dry to mesic, disturbed, usually open areas in the Hawaiian Islands.
It occurs in coastal areas, in lowland dry shrublands and forests, and in lowland mesic
grasslands and forests [49].
Most coastal areas once dominated by native pili grass (Heteropogon contortus)
are now dominated by nonnative shrubs and trees on gently sloping to level
lowlands; however, pili grass is still dominant on very steep slopes, cliff
ledges, and eroded areas. In many of these areas, however, pili grass appears to
have been replaced by nonnative grasses including molasses grass, Natal redtop
(Melinis repens), and fountain grass (Pennisetum setaceum) [49].
Molasses grass occurs in 3 native lowland dry shrubland community types and 2
native lowland dry forest community types described by Wagner and others [49].
On leeward Moloka`i, molasses grass occurs in a nonnative-dominated herb layer
with Natal redtop in a rare community dominated by the native shrub `ohai (Sesbania
tomentosa); and in open shrublands codominated by the native shrubs ko`oko`olau
(Bidens menziesii subsp. menziesii) and `āweoweo
(Chenopodium oahuense) where the sparse grass understory also includes
pili grass, annual panicgrass (Panicum spp.), and Natal redtop. Nonnative
grasses, including molasses grass, may be present but not dominant in native `a`ali`i
(Dodonaea viscosa)-dominated shrublands. Molasses grass occurs in native koa
(Acacia koa) forest communities and in a unique forest community dominated
by olopua (Nestegis sandwicensis) and lama (Diospyros sandwicensis)
that is heavily damaged by axis deer and invaded by several nonnative plants, in
addition to molasses grass [49].
In lowland mesic communities, molasses grass occurs in 2 grassland types and 2
forest types described by Wagner and others [49], and it is included among
several nonnative plant species that may be Âcapable of displacing some native
lowland mesic shrublands. Many occurrences of the kāwelu (Eragrostis variabilis)
grassland community type are invaded by nonnative grasses including molasses
grass. A molasses grass community type occurs on most of the main islands in the
same geographic, climatic, and edaphic settings as mesic shrublands and kāwelu
grasslands, on sites formerly dominated by native and other nonnative grasses and
released from grazing pressure. Molasses grass also occurs in native `ōhi`a
(Metrosideros polymorpha) forest types and in nonnative Brazilian pepper
(Schinus terebinthifolius) forest types, which typically occur on abandoned
agricultural sites and pasturelands [49].
Molasses grass may reproduce from seeds [5,11,21,34,46], stolons [5,27,28,33], basal meristems [45], or rhizomes [13,21,46].
At the time of this writing (2008), there is no information on molasses grass breeding system, pollination, seedling establishment and growth, or seed production.
Seed dispersal: Molasses grass seeds are dispersed by wind [38].
Seed banking: Molasses grass seeds can occur in the soil seed bank [11,46]; however, seed longevity is unknown. Tunison and others [46] found that molasses grass seed is "ubiquitous" in the soil of unburned `ōhi`a woodlands in Hawaii. Near Kipuka Nene, Hawai`i Volcanoes National Park, D'Antonio and others [11] extracted molasses grass seeds from soil samples 3 inches (8 cm) deep and 1.8 inches (4.5 cm) wide in October 1991 and February and June 1992. Following extractions, molasses grass seeds were planted in containers and seedling emergence was measured for 3 months following each of the 3 extraction dates. Seed bank samples were taken from an unburned woodland, a woodland burned in 1970, a woodland burned in 1987, and a site burned both in 1970 and 1987. In general, seedling emergence was significantly greater from seeds extracted from burned sites (P<0.05) [11].
Mean number of molasses grass seedlings emerging from soil samples in unburned and burned woodlands near Kipuka Nene, Hawai`i Volcanoes National Park [11]
Habitat Collection date October 1991 February 1992 June 1992 Unburned 1.15a* 5.60a 1.50a Burned in 1987 2.60b 15.25a,b 8.10b Burned in 1970 10.00b 25.40b 8.10b Burned in 1970 and 1987 3.25b 17.90b 5.80a,b *Different lowercase letters in the same column indicate a significant difference (P<0.05)Germination: Molasses grass seed germination is better with increasing sunlight, is largely unaffected by heat [11], and is promoted by elevated CO2 [5]. In a controlled outdoor experiment, molasses grass seed germination and growth were significantly better with 49% or more sunlight (P<0.05). At 1%, 3%, and 33% of full sunlight, average (SE) molasses grass seed germination rates were 10.4% (1.8), 12.7% (2.5), and 13.9% (1.8), respectively. At 49% and 100% full sunlight, germination rates were 27.1% (2.6) and 25.5% (3.1), respectively [11].
The germination rate of heat-treated molasses grass seeds was not significantly different than that of unheated seeds (P<0.80) [11]. The average germination rate of molasses grass seeds heated for 4 minutes at temperatures ranging from 140 °F to 250 °F (60 °C-120 °C) was 18.8% [11].
Vegetative regeneration: Molasses grass regenerates vegetatively by stolons [5,27,28,33], basal meristems [45], and rhizomes [13,21,46].
Molasses grass is shade-intolerant [11] and thrives in open, disturbed areas [4,19,34] such as burned sites [13,29,45]. Molasses grass is not tolerant of heavy grazing [32,49]. Establishment and spread of molasses grass in native plant communities in Hawaii may alter succession in invaded communities [1].
At Hawai`i Volcanoes National Park, nonnative bush beardgrass (Schizachyrium condensatum) is abundant in unburned, seasonally dry woodlands [11]. Following fire, molasses grass partially replaces bush beardgrass. In the absence of fire, molasses grass establishment in bush beardgrass communities is depressed due to low light levels. In a controlled experiment, molasses grass established in unburned woodlands following the removal of bush beardgrass. Additionally, when molasses grass seedlings established in bush beardgrass communities or when bush beardgrass and molasses grass seedlings emerge on the same site simultaneously, molasses grass came to dominate the site [11].
Lowland dry shrublands in Hawaii are relatively intolerant of fire and are often replaced by nonnative-dominated communities after fire. See FIRE REGIMES for more information on the role of molasses grass in these changes. In Venezuela, Baruch and others [3,4] suggest that the spread of molasses grass was likely aided by the burning of savannas in the Coastal Mountains to improve pastures. Molasses grass may alter the successional dynamics of shrublands in Hawaii [1,49]. Molasses grass "appears capable of displacing" many of the native lowland mesic shrublands in Hawaii [49]. On the upper leeward slopes of Moloka`i Island, monospecific molasses grass stands and shrub (pūkiawe (Styphelia tameiameiae) and `a`ali`i) stands with molasses grass had significantly greater soil nitrogen pools than uninvaded shrublands (P<0.05). The increase of nitrogen may promote further establishment of molasses grass and other nonnatives in native Hawaiian shrublands that are normally nutrient-poor [1]. Conversion of Hawaiian woodlands to grasslands via fires appears to increase nitrogen available to plants. In a molasses grass-dominated grassland converted via fire from a `ōhi`a woodland in Hawai`i Volcanoes National Park, net nitrogen mineralization was 3.4 times greater than in an unburned `ōhi`a woodland [27].
Molasses grass can tolerate low grazing pressure, giving it an advantage over less tolerant species [33]. However, molasses grass is intolerant of heavy grazing, and changes in dominance have been observed with changes in grazing pressure. Beginning in the 1970s in Hawai`i Volcanoes National Park, there has been a shift in the central coastal lowland grasslands from dominance of annual and short-statured perennial grasses to dominance of mid-sized, fire-tolerant, perennial grasses including molasses grass [32]. Following the removal of feral goats from the park between 1971 and 1975 [31,33], Japanese lovegrass (Eragrostis amibilis), golden false beardgrass (Chrysopogon aciculatus), Bermudagrass (Cynodon dactylon), and native pili grass were replaced by nonnative thatching grass (Hyparrhenia spp.) and molasses grass. In 1970 there were approximately 14,000 goats in the park and by 1980 there were fewer than 200 [44]. At Pu'u Kaone in Hawai`i Volcanoes National Park, goat removal led to molasses grass dominance. In a 5-year period, molasses grass became a dominant species with 25% cover in a formerly closed golden false beardgrass-Bermudagrass community [32]. Molasses grass grasslands subjected to heavy grazing by axis deer on Lāna'i are "becoming barren, eroded landscapes" [49].
Ko e puakatau ko e ongo faʻahinga mohuku ia, kae ko e ongo kāinga kehe. ʻOku na tātātaha. Ko e ngaahi ʻuhinga tatau ʻo e U. mutica: Brachiaria mutica , Panicum muticum, mo e hā fua
Ko e puakatau ko e ongo faʻahinga mohuku ia, kae ko e ongo kāinga kehe. ʻOku na tātātaha. Ko e ngaahi ʻuhinga tatau ʻo e U. mutica: Brachiaria mutica , Panicum muticum, mo e hā fua
Melinis minutiflora, commonly known as molasses grass, is a species of grass.[1]
It is a perennial grass native to Africa, where it occurs in disjunct populations (an arc from central Angola to Cameroon in western central africa, the areas around Ruwenzori Mountains and Mount Kenya in eastern Africa.[1] Its seeds are dispersed by wind.[1] Molasses grass usually grows to be thirty to sixty inches tall, and it forms mats when its long, slender stems lay on top of each other in layers up to four feet deep.[1] Molasses grass can spread up other plants, using them as support, like a vine.[1] It has fragrant foliage and colorful inflorescences.[1] It blooms for short periods with differing bloom times depending on where the grass is located.[2] Molasses grass generally flowers in the southern hemisphere between April and June and in the northern hemisphere in November.[1][2]
It was introduced to tropical areas such as Hawaii for livestock feed, and is now naturalized in some areas.[1] Around 1812, molasses grass took root in Brazil and spread through abandoned coffee plantations.[1] Similarly, around 1900, molasses grass was introduced in Hawaii for cattle grazing.[1] In Hawaii, it continued to spread, though its spread was hindered by feral goats.[1] It is considered an invasive species in many parts of the world, including some Pacific Islands and South America.[3]
Molasses grass plays a large role in fire ecology in the regions where it grows.[1] In the Brazilian savanna (Cerrado) this species is invasive and dominant due to the increased frequency of fire.[4] When a wild fire occurs, molasses grass is very quick to colonize the disturbed area.[1] Examples of this are seen in almost every region where molasses grass is found, including Australia, Brazil, and Hawaii where molasses grass even increases the risk of fire in the areas in which it establishes.[1] Molasses grass increases the likelihood of fires where it has established because it is brittle and burns easily.[1] This cycle where molasses grass establishes, burns easily, then reestablishes and burns again is known as the grass/fire cycle, and it undermines native plants’ ability to grow and thrive in their native environment.[1] One result of this cycle is a drop in biodiversity in the affected area.[5]
Melinis minutiflora, commonly known as molasses grass, is a species of grass.
It is a perennial grass native to Africa, where it occurs in disjunct populations (an arc from central Angola to Cameroon in western central africa, the areas around Ruwenzori Mountains and Mount Kenya in eastern Africa. Its seeds are dispersed by wind. Molasses grass usually grows to be thirty to sixty inches tall, and it forms mats when its long, slender stems lay on top of each other in layers up to four feet deep. Molasses grass can spread up other plants, using them as support, like a vine. It has fragrant foliage and colorful inflorescences. It blooms for short periods with differing bloom times depending on where the grass is located. Molasses grass generally flowers in the southern hemisphere between April and June and in the northern hemisphere in November.
Melinis minutiflora es una hierba perenne del género Melinis. M. minutiflora es originaria de África. Se propaga en forma de estera. Presenta tallos erectos de hasta 1.5 metros de alto. Las hojas están cubiertas por un follaje oloroso y pegajoso, de inflorescencia de color rojizo. Florece por período corto. Se cree que el olor fresco de M. minutiflora es repelente de insectos y de serpientes.
En Venezuela es conocida con el nombre de Capin Melao, cubre extensas áreas del Parque nacional El Ávila, y es considerada por muchos de los caraqueños como la causante de las alergias que sufre la población en la estación seca de diciembre, enero y febrero.
Fue introducida en países tropicales de América como forraje para la cría de animales, y pronto se naturalizó. No obstante, es considerada una maleza en muchas partes del mundo, incluyendo Hawái, Brasil, Venezuela y Colombia, y puede haber contribuido a la desaparición de especies nativas en diversas regiones. Ha sido utilizada, aun así, como especie pionera en la plantación de suelos pobres, y neutraliza otras malezas que puedan aparecer.
Son plantas perennes o anuales; con tallos de hasta 180 cm de largo pero generalmente más cortos, sólidos, decumbentes y a menudo enraizando cerca de la base, muy ramificados; entrenudos papiloso-pilosos; nudos barbados; plantas hermafroditas. Vainas densamente papiloso-pilosas, los tricomas con ampollas víscidas de material resinoso oloroso; lígula una hilera de tricomas, de 1 mm de largo; láminas linear-lanceoladas, 5–15 cm de largo y 5–12 mm de ancho, aplanadas, velutinas. Inflorescencia una panícula terminal, angostamente piramidal, 9–22 cm de largo y 2–7 cm de ancho, purpúrea, ramas patentes solamente durante la antesis, ramitas flexuosas; espiguillas oblongas, 1.6–2.5 mm de largo, algo comprimidas lateralmente, glabras, con 2 flósculos; desarticulación por debajo de las glumas, la espiguilla caediza como una unidad; glumas desiguales, membranáceas, la inferior suborbicular, 0.2–0.3 mm de largo, la superior lanceolada, 1.9–2.5 mm de largo, recta, fuertemente 5–7-nervia, bífida con una arista diminuta entre los lóbulos; pálea inferior ausente; flósculo inferior estéril; lema inferior 1.8–2.4 mm de largo, 3–5-nervia, la arista 5–12 mm de largo; flósculo superior bisexual, 1.5–2 mm de largo; lema superior ovada, más corta que la inferior, membranácea, delgada y translúcida, 1-nervia, lisa y brillante; pálea superior casi tan larga como la lema superior, similar en textura; lodículas 2; estambres 3, las anteras 1–1.5 mm de largo, purpúreas; estilos 2. Fruto una cariopsis, fusiforme; embrión ca 1/2 la longitud de la cariopsis, hilo punteado.[1]
Melinis minutiflora fue descrita por Ambroise Marie François Joseph Palisot de Beauvois y publicado en Essai d'une Nouvelle Agrostographie 54, pl. 11, f. 4. 1812.[1]
Melinis minutiflora es una hierba perenne del género Melinis. M. minutiflora es originaria de África. Se propaga en forma de estera. Presenta tallos erectos de hasta 1.5 metros de alto. Las hojas están cubiertas por un follaje oloroso y pegajoso, de inflorescencia de color rojizo. Florece por período corto. Se cree que el olor fresco de M. minutiflora es repelente de insectos y de serpientes.
Melinis minutiflora, mélinis à petites fleurs, herbe à mélasse ou herbe à miel, est une espèce de plantes monocotylédones de la famille des Poaceae, sous-famille des Panicoideae, originaire d'Afrique tropicale.
Melinis minutiflora est une graminée herbacée vivace, qui peut atteindre de 80 à 150 cm de haut. Elle forme d'épais tapis pouvant atteindre jusqu'à un mètre d'épaisseur quand ses longue tiges élancées s'affaissent les unes sur les autres. Elle peut également s'étendre sur d'autres plantes, les utilisant comme support, à la manière d'une plante grimpante.
Les feuilles sont simples, engainantes et ont une ligule poilue[1]. Elles portent sur leurs deux faces des poils à la base desquels se trouvent des poils glanduleux qui sécrètent un liquide collant, à l'odeur sucrée[2],[3] (d'où les noms vernaculaires d'« herbe à miel » ou « herbe à mélasse »).
L'inflorescence se présente comme une panicule rousse assez lâche, de 10 à 20 centimètres de long, pourvue d'épillets munis de longues arêtes poilues[1].
La période de floraison est courte et l'époque de floraison peut varier selon les endroits où pousse la plante[4]. Melinis minutiflora fleurit généralement entre avril et juin dans l'hémisphère sud et en novembre dans l'hémisphère nord.
Les fruits sont des caryopses qui sont dispersés par le vent (anémochorie)[1].
L'aire de répartition originelle de Melinis minutiflora se situe en Afrique tropicale[1], où elle se présente sous la forme de deux populations disjointes dans l'ouest et dans l'est du continent.
L'espèce est largement présente dans de nombreuses régions tropicales et subtropicales. Elle s'est souvent naturalisées après avoir été introduite comme plante fourragère (avec peu de succès, car cette herbacée est finalement peu appréciée par le bétail)[1]. On la rencontre notamment en Asie tropicale (Inde, Indochine, Papouasie-Nouvelle-Guinée) et tempérée (Chine, Taïwan), en Australie, en Océanie (Hawaï, Palaos, Polynésie française, Nouvelle-Calédonie, Niue, Tonga, Wallis-et-Futuna), en Amérique du Nord (Mexique et sud-est des États-Unis (Floride) et dans certaines parties de l'Amérique centrale et des Caraïbes (Antilles, Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, Panama) et de l'Amérique du Sud, en particulier au Brésil, mais également en Guyana, Suriname, Venezuela, Argentine, Chili, Paraguay, Uruguay, Bolivie, Colombie, Équateur, Pérou)[3],[5].
En Nouvelle-Calédonie, elle s'est répandue jusqu'à constituer la principale composante herbacée de la savane de la chaîne centrale[6].
Melinis minutiflora est une plante pyrophile[1], qui joue un grand rôle dans l'écologie du feu dans les régions où elle croît[2]. Dans la savane brésilienne (cerrado), cette espèce est devenue envahissante et dominante en raison de la fréquence accrue des incendies[7]. Quand un incendie se produit, l'herbe à mélasse, espèce pionnière des milieux ouverts ou incendiés, colonise très rapidement la zone perturbée[1]. On constate des exemples de ce phénomène dans presque toutes les régions où l'herbe à mélasse s'est naturalisée, en particulier en Australie, au Brésil, à Hawaï et en Nouvelle-Calédonie (où elle aurait été introduite en 1940)[1],[6],[8], où cette graminée accroît le risque d'incendie dans les zones où elle s'est établie. Melinis minutiflora augmente la probabilité des incendies partout où elle est installée parce que c'est une plante cassante, fragile, qui brûle facilement[2].
Ce cycle « herbe / incendie » dans lequel l'herbe à mélasse s'établit, brûle facilement, puis se rétablit et brûle à nouveau, porte atteinte à la capacité des plantes autochtones de croître et prospérer dans leur environnement d'origine[2]. Une des conséquences de ce cycle est une baisse de la biodiversité dans les zones concernées[9].
L'espèce Melinis minutiflora a été décrite par le botaniste français, Palisot de Beauvois, et publiée en 1812 dans son Essai d'une nouvelle agrostographie (p. 54, pl. 11, f. 4.)[10].
Selon Catalogue of Life (21 octobre 2016)[15] :
Selon Tropicos (21 octobre 2016)[16] (Attention liste brute contenant possiblement des synonymes) :
Melinis minutiflora, mélinis à petites fleurs, herbe à mélasse ou herbe à miel, est une espèce de plantes monocotylédones de la famille des Poaceae, sous-famille des Panicoideae, originaire d'Afrique tropicale.
Melinis minutiflora é uma espécie de planta com flor pertencente à família Poaceae.
A autoridade científica da espécie é P.Beauv., tendo sido publicada em Essai d'une Nouvelle Agrostographie 54, pl. 11, f. 4. 1812.[1]
É uma gramínea nativa da África , popularmente conhecida no Brasil como Capim-gordura. Foi introduzida no Brasil com a finalidade de atuar como forrageira e formar pastagens por ser uma planta rústica e de rápido crescimento. No entanto naturalizou-se e transformou-se em invasora de diversos ecossistemas, como o cerrado.
No processo de invasão, a planta cresce por cima da vegetação herbácea nativa causando sombreamento e morte dessa vegetação, deslocando espécies nativas de flora e fauna. Também gera aumento da temperatura de incêndios no cerrado, com eliminação tanto das plantas nativas quanto do banco de sementes pré-existente no solo.
Trata-se de uma espécie presente no território português, nomeadamente no Arquipélago da Madeira.
Em termos de naturalidade é introduzida na região atrás indicada.
Não se encontra protegida por legislação portuguesa ou da Comunidade Europeia.
Melinis minutiflora é uma espécie de planta com flor pertencente à família Poaceae.
A autoridade científica da espécie é P.Beauv., tendo sido publicada em Essai d'une Nouvelle Agrostographie 54, pl. 11, f. 4. 1812.
É uma gramínea nativa da África , popularmente conhecida no Brasil como Capim-gordura. Foi introduzida no Brasil com a finalidade de atuar como forrageira e formar pastagens por ser uma planta rústica e de rápido crescimento. No entanto naturalizou-se e transformou-se em invasora de diversos ecossistemas, como o cerrado.
No processo de invasão, a planta cresce por cima da vegetação herbácea nativa causando sombreamento e morte dessa vegetação, deslocando espécies nativas de flora e fauna. Também gera aumento da temperatura de incêndios no cerrado, com eliminação tanto das plantas nativas quanto do banco de sementes pré-existente no solo.
Melinis minutiflora là một loài thực vật có hoa trong họ Hòa thảo. Loài này được P.Beauv. mô tả khoa học đầu tiên năm 1812.[1]
Melinis minutiflora là một loài thực vật có hoa trong họ Hòa thảo. Loài này được P.Beauv. mô tả khoa học đầu tiên năm 1812.
糖蜜草（学名：Melinis minutiflora），为禾本科糖蜜草属下的一个植物种。[1]
这是一篇黍亞科（英语：Panicoideae）小作品。你可以通过编辑或修订扩充其内容。 
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