Invasive Plant Science and Management 2014 7:000–000 Repeated Selective Cutting Controls Neotropical Bracken (Pteridium arachnoideum) and Restores Abandoned Pastures (original) (raw)
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The bracken fern (Pteridium arachnoideum (Kaulf.) Maxon) dilemma in the Andes of Southern Ecuador
Ecotropica, 2003
Bracken fern (Pteridium aquilinum (L.) Kuhn) is one of the world's most powerful weeds, especially in agricultural areas. Its vigor and resistance to any kind of non-polluting pest control result from its extensive rhizome system. Growth of this rhizome system is strongly promoted by fire. As elsewhere in the tropics, farmers in the Andes of southern Ecuador make extensive use of fire to convert primary forest into arable land and to maintain their pastures. This communication addresses, from a phytosociological viewpoint, the ecological problems arising from the use of fire as an agricultural tool in the presence of the extremely aggressive and fire-tolerant bracken fern Pteridium arachnoideum. Repeated burning of the pastureland weakens the competitive strength of the most important pasture grass Setaria sphacelata, while the competitive strength of bracken increases. Pastures are finally abandoned when Pteridium has become completely predominant. Wind-dispersed seeds of several weedy Asteraceae and Melastomataceae species germinate under the canopy of the bracken leaves and, due to the steepness of the slopes, the seedlings receive sufficient light for further growth. The majority of these species are bushes that finally overtop the bracken leaves and can successfully compete with the shade intolerant fern. A vegetation composed of dense patches of Pteridium interspersed with individual bushes develops, which, because of the immense seed production of the bushes and the vigor of the bracken, is very stable and appears to be a longlasting and even at times the final successional stage. Since natural regeneration of the indigenous forest is very unlikely in these areas, reforestation may be the only way out of the dilemma caused by the extensive use of fire and the fire-tolerance of bracken.
The Bracken fern (Pteridium arachnoideum Kaulf.) dilemma in the Andes of Southern Ecuador
Ecotropica
Bracken fern (Pteridium aquilinum (L.) Kuhn) is one of the world's most powerful weeds, especially in agricultural areas. Its vigor and resistance to any kind of non-polluting pest control result from its extensive rhizome system. Growth of this rhizome system is strongly promoted by fire. As elsewhere in the tropics, farmers in the Andes of southern Ecuador make extensive use of fire to convert primary forest into arable land and to maintain their pastures. This communication addresses, from a phytosociological viewpoint, the ecological problems arising from the use of fire as an agricultural tool in the presence of the extremely aggressive and fire-tolerant bracken fern Pteridium arachnoideum. Repeated burning of the pastureland weakens the competitive strength of the most important pasture grass Setaria sphacelata, while the competitive strength of bracken increases. Pastures are finally abandoned when Pteridium has become completely predominant. Wind-dispersed seeds of several weedy Asteraceae and Melastomataceae species germinate under the canopy of the bracken leaves and, due to the steepness of the slopes, the seedlings receive sufficient light for further growth. The majority of these species are bushes that finally overtop the bracken leaves and can successfully compete with the shade intolerant fern. A vegetation composed of dense patches of Pteridium interspersed with individual bushes develops, which, because of the immense seed production of the bushes and the vigor of the bracken, is very stable and appears to be a longlasting and even at times the final successional stage. Since natural regeneration of the indigenous forest is very unlikely in these areas, reforestation may be the only way out of the dilemma caused by the extensive use of fire and the fire-tolerance of bracken.
Invasive Plant Science and Management, 2014
Neotropical bracken fern invades disturbed forests and burned and abandoned pastures in Latin America, inhibiting the growth of associated vegetation and altering community structure. Cutting of all aboveground vegetation every 6 to 12 mo has proven to be inefficient as a control method. We studied the impact of selective cutting of bracken every 2 mo, shading, and a combination of cutting + shading during 14 mo in a bracken-dominated, abandoned pasture in Veracruz, Mexico. At the end of the experiment, cutting with or without shading drastically reduced bracken cover from >90% to less than 1%, decreased leaf number from 18 to fewer than two leaves per m2, and depleted bracken leaf biomass. The significant reduction of bracken was correlated with a significant 3.9- to 5.7-fold increase in richness of other plant species. Cutting without shading was the only treatment that significantly reduced rhizome biomass to less than 62% of control plots, whereas cutting + shading was the on...
Vegetatio, 1996
A comparative field study of caudatum and arachnoideum, the two Pteridium aquilinum varieties of the caudatum subspecies known to grow in the neotropics, was performed in a montane savanna habitat of the Venezuelan Andes that was affected by wildfire. Frond size, ramet density and spatial distribution, blade and rhizome biomass, and frond elongation and expansion rates were measured in separate, isolated stands each containing only one bracken variety and covering approximately the same area (,-~540 m2). In addition to clearly discernible morphological differences, caudatum and arachnoideum were found to possess distinct features: caudatum tends to develop open stands of relatively shorter blades of 76.6 4-0.89 cm(# -t-SE) of rachis length and lower ramet density (1.6 fronds m -2, max. = 7 fronds m -2) whereas arachnoideum grows into longer, more expanded fronds 124 -I-1.6 cm tall and significantly higher ramet density (5.1 fronds/m 2, max. = 14.6 fronds m-z). The sum of aerial and underground biomass was found to be notably larger for arachnoideum (8522 4-614 Kg/ha) than for caudatum (1929 4-131 Kg ha -1) in stands growing under the same habitat conditions. Therefore the spatial distribution of arachnoideum appeared considerably more compact than that of caudatum. Blade growth rates and development time were also very different. Newly emerged caudatum croziers developed into mature blades within 42 to 48 days following an inverse exponential curve whereas arachnoideum blades required 70 to 75 days to reach maturity following a linear development. All the above dissimilarities are interpreted as the hitherto unreported indication of diverging growth strategies of two cohabitant bracken varieties following fire.
Botanical characteristics, toxicity and control of bracken fern (pteridium aquilinum (l.) kuhn)
Zbornik Veleučilišta u Rijeci
Bracken (Pteridium aquilinum (L.) Kuhn) is cosmopolitan fern, found at varying altitudes on all continents except Antarctica. It is an aggressive colonizer and can appear in various plant communities, but an important characteristic is its ability to dominate in dense patches. Once establish, the deep-set rhizomes are nearly impossible to eradicate. In Croatia, bracken dominate on specific habitat type called “bujadnice” in Lika region, but can also be found in herbaceous layers in following forest communities: As. Betulo-Quercetum; As. Pteridio-Betuletum; As. Potentillo albae-Quercetum pubescentis; As. Castaneo sativae-Fagetum; As. Helleboro nigri-Piceetum. Bracken fern is significant problem for livestock-based extensive agriculture, because it causes a range of syndromes in farm animals including thiamine deficiency, acute hemorrhagic syndrome, bright blindness, enzootic hematuria and upper alimentary carcinoma. Man may consume the toxins of bracken either directly or indirectly....
Phytotaxa, 2018
Based on the morphological study of ca. 470 specimens and geographical studies, we here propose the recognition of six morphotypes within the South American Pteridium esculentum (= P. arachnoideum s.l., or P. aquilinum var. arachnoideum sensu Tryon, or P. esculentum subsp. arachnoideum sensu Thomson). Three of them are widely distributed and well-defined, and we regard them as subspecies of P. esculentum: P. esculentum subsp. arachnoideum s. str., P. esculentum subsp. campestre, comb. et stat. nov., and P. esculentum subsp. gryphus. The other three are more rare. One of these is a pedomorphic form of P. esculentum subsp. arachnoideum, which we name as P. esculentum subsp. arachnoideum var. paedomorficum, nom. nov. The other is a glabrous form of P. esculentum subsp. gryphus, which we name P. esculentum subsp. gryphus var. harpianum, var. nov. The third is a putative hybrid between P. esculentum subsp. arachnoideum and P. esculentum subsp. campestre. All six taxa are keyed, described, illustrated, mapped, and discussed. Pteridium esculentum subsp. arachnoideum s. str. forms an arc of distribution from eastern, to southern, to western South America (but not occurring west of the Andes); Pteridium esculentum subsp. campestre forms an arc of distribution from northeastern Brazil to northern South America (not occurring west of the Andes either); and P. esculentum subsp. gryphus forms an arc of distribution from western to northern South America (occurring also west of the Andes and in Galapagos). This one is morphologically more similar to the Australasian P. esculentum subsp. esculentum.
Fuel and Energy Abstracts, 2011
Biological invasion is one of the major components of global change. In the Brazilian Cerrado, the fern Pteridium arachnoideum (neotropical bracken) is a potentially invasive species which is expected to change the vegetation structure of savannas. We assessed effects of the dominance of P. arachnoideum on the diversity of woody Cerrado species. We compared three sites dominated by neotropical bracken with three sites without neotropical bracken. We used multivariate analyses of variance and rarefaction curves with confidence limits to test whether the groups of species found in invaded areas were different from those found in non-invaded ones. We also analyzed the density of individuals and species and the mean area at breast height per plot. We found significant floristic differences between the areas. The diversity and the densities in the invaded areas were lower than in non-invaded ones. However, we did not observe differences in the mean area at breast height of woody plants. Thus, the P. arachnoideum invasion is a potential threat to Cerrado biodiversity. Management efforts should be made to control the bracken, since its dominance in the plant community may lead to impoverishment and simplification of the savanna vegetation.
Journal of Applied Ecology, 2013
1. Large areas of agricultural land around the world are degraded as a consequence of dominance by bracken fern (Pteridium spp.). Tropical production systems based on shifting cultivation and cattle breeding are particularly vulnerable to invasion of this species. In spite of this, effective methods for tropical bracken control are limited. 2. Fast-growing tree species have been used successfully to out-compete aggressively colonizing heliophytes and trigger natural succession. Drawing on a traditional Mayan management technique, we evaluate the potential of the pioneer tree balsa (Ochroma pyramidale) to control Pteridium caudatum in Chiapas, Mexico. We tested different bracken cutting frequencies and balsa propagation methods in a factorial randomized block experiment. Eighteen months later, we quantified bracken biomass under the young balsa canopy. 3. Living bracken rhizome biomass correlated significantly with balsa basal area, leaf litter biomass and understorey light intensity. While bracken rhizomes persisted in control plots, it was completely eradicated in plots with a minimum balsa basal area of 11 m 2 ha À1 . This threshold value was reached in less than 18 months with any of the tested propagation methods (seed broadcasting, direct sowing or nursery seedlings), on the condition of at least monthly bracken cutting during the first six months. 4. The ability of fast-growing broad-leaved pioneer trees like balsa to quickly out-compete bracken fern offers opportunities for large-scale application in tropical rural areas where economic and technical resources are scarce. 5. Synthesis and applications. Mayan subsistence farmers traditionally use balsa to outcompete invasive weeds, including bracken fern. Here, we highlight the usefulness of this method for quick and effective bracken control in southern Mexico. This approach, in combination with balsa's short rotation cycle, creates opportunities to rapidly convert bracken land into forest stands with commercial potential, thus providing local income and increasing the likelihood of adoption by rural people. We encourage further research to test the potential of balsa and other fast-growing pioneer trees species for controlling bracken and similar weeds.
The taxonomy of bracken ( Pteridium : Dennstaedtiaceae) in Australia
Australian Systematic Botany, 1989
Investigation of Australian bracken ferns in the genus Pteridium (Dennstaedtiaceae) shows that there is one common and widespread species, P. esculentum, found in all States, and a second species, P. revolutum, confined to north-eastern Queensland and the Northern Territory. Plants first described as P. aquilinum var. yarrabense and more recently referred to P. semihastatum are intermediate in morphology between the other two species and have aborted spores. They are now believed to be sterile hybrids between P. esculentum and P. revolutum. This is the first record of wild hybrids in Pteridium and provides strong evidence that the concept of a monotypic genus is incorrect. Other evidence for speciation within the genus is reviewed.
Growth of Tropical Bracken (Pteridium arachnoideum): Response to Weather Variations and Burning
Invasive Plant Science and Management, 2010
The ecology of tropical bracken, which occurs in tropical regions, is not well known. We studied its response to weather variations and burning in the south Ecuadorian Andes, where this weed had already overgrown 40% of the pastureland. In field observations, a constant 1 : 1 ratio of emerging and dying leaves suggested limitation of frond density by nutrient shortage. Short-term deviations from that ratio could be related to weather variations. Spells of dry weather temporarily increased mortality but stimulated emergence of new fronds. Lifespan of the fronds produced immediately after a fire was longer than of those produced during unaffected bracken growth. A burst of frond development during the initial 2 to 3 mo was observed after a fire followed by self-thinning to a stable level. To analyze the effect of fire on bracken, rhizomes were treated with heat pulses. Rhizomes were heat tolerant up to 70 C, and frond production from short shoots was enhanced by elevated temperature. ...