The Benefits and Potential Risks of Woody Legume Introductions

Hughes, Colin E.; Styles, B. T.

doi:10.1080/01435698.1987.9752826

Cited by 42 publications

(29 citation statements)

References 32 publications

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“…Legumes constitute one of the most important families of invasive plants in terms of the scope of environmental impact in habitats throughout the world (Hughes and Styles 1989;Lonsdale 1994;Cronk and Fuller 1995;Paynter et al 2003). Although access to compatible strains of nodule bacteria (rhizobia) is likely to be a critical factor governing invasion success of legumes (Richardson et al 2000;Parker 2001), biologists currently do not have a clear understanding of legume symbiotic interactions during range expansion.…”

Section: Introductionmentioning

confidence: 99%

Nodule Symbiosis of Invasive Mimosa pigra in Australia and in Ancestral Habitats: A Comparative Analysis

2006

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Ninety isolates of root nodule bacteria from an invasive Mimosa pigra population in Australia were characterized by PCR assays and by sequencing of ribosomal genes. All isolates belonged to the same bacterial genus (Burkholderia) that predominates on M. pigra in its native geographic range in tropical America. However, the Australian Burkholderia strains represented several divergent lineages, none of which had a close relationship to currently known Burkholderia strains in American M. pigra populations. Inoculation of M. pigra with Australian strains resulted in equal or higher plant growth and nodule nitrogenase activity (measured by acetylene reduction assays) relative to outcomes with bacteria from M. pigra's native geographic region. The main difference in symbiotic phenotype for bacteria from the two regions involved responses to an alternate Mimosa host species: Central American strains failed to fix nitrogen in association with Mimosa pudica, while most Australian Burkholderia isolates tested had high nodule nitrogenase activity in association with both Mimosa species. Invasive M. pigra populations in Australia have therefore acquired a diverse assemblage of nodule bacteria that are effective nitrogenfixing symbionts, despite having a broader host range and a distant genetic relationship to bacterial strains found in the plant's ancestral region.

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Section: Introductionmentioning

confidence: 99%

Nodule Symbiosis of Invasive Mimosa pigra in Australia and in Ancestral Habitats: A Comparative Analysis

2006

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“…Plants in the family Leguminosae rank among the most widely disseminated taxa spread to new regions by human activities (Hughes & Styles, 1989;Lonsdale, 1994;Cronk & Fuller, 1995). Although symbiosis with nitrogen-fixing nodule bacteria (rhizobia) is a key feature of legume ecology, biologists currently lack a clear understanding of symbiotic interactions during range expansion.…”

Section: Introductionmentioning

confidence: 99%

Growth of an invasive legume is symbiont limited in newly occupied habitats

Parker

Małek²,

Parker

2006

Diversity and Distributions

118

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Mutualisms may play an important role in the establishment and invasion success of introduced species, but their influence is little studied. To test whether a lack of root nodule symbionts may limit the performance of invasive legumes, seedlings of Cytisus scoparius were introduced to an old-field habitat and then either inoculated with Bradyrhizobium strains from existing C. scoparius populations, or left uninoculated. In two separate years, inoculation more than doubled average plant biomass. For uninoculated transplants, nodule formation was positively correlated with proximity to plants of the native legume Desmodium canadense , but not related to distance from a second legume species, Apios americana. Polymerase chain reaction assays and DNA sequencing confirmed that bacteria isolated from uninoculated C. scoparius plants were indistinguishable from Bradyrhizobium strains in root nodules of D. canadense . By contrast, bacterial strains associated with A. americana were never found in C. scoparius nodules. Transplants in seven other habitats across a 160 km region also showed a highly significant, fivefold biomass increase in response to inoculation. Thus, colonizing legumes can suffer from a scarcity of nodule symbionts. However, certain indigenous legumes may create favourable microhabitats for invasion, by increasing symbiont availability in their vicinity.

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“…Proponents of agroforestry have often found it difficult to defend their decisions from the vigorous criticisms of invasion biologists regarding the invasive potential of woody species that they promote for soil rehabilitation, reforestation, commercial production or other agronomic uses such as fallow crops (Hughes and Styles 1989;Hughes 1994;Richardson 1998;Binggeli 2001;Richardson et al 2004). Their muted response to these criticisms has been in the form of an invasive species policy published by the World Agroforestry Centre (ICRAF 2004) which recommends that new agroforestry introductions be subject to weediness risk assessments.…”

Section: Introductionmentioning

confidence: 97%

Hybrid improved tree fallows: harnessing invasive woody legumes for agroforestry

2012

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For several decades, agroforestry specialists have promoted the planting of fallow fields with nitrogen-fixing, fast-growing trees or shrubs to accelerate soil rehabilitation and provide secondary products like woodfuel. Yet, such 'improved fallows' have not been widely adopted, in part due to the costs of labour and seedlings. In some situations, however, farmers have developed novel approaches to agroforestry fallows by taking advantage of spontaneous invasions of woody leguminous tree species present in the vicinity of their fields. In this paper, we examine cases from Réunion, highland Madagascar, the Bateke plateau in Congo, and the Palni hills of southern India where farmers have adapted their cultivation practices to take advantage of the invasive characteristics of Australian acacias that were introduced earlier for other reasons. We focus on the key social, economic, and environmental factors that influence farmers in these places to gain opportunistic benefit from these introduced tree species that biologists have been deemed invasive and damaging to local ecosystems and biodiversity. We conclude that opportunistic fallowing of invasives can be viewed as a hybrid strategy combining elements of natural fallows and improved fallows-which we call 'hybrid improved fallows'-in that it takes advantage of the 'weedy' characteristics of introduced leguminous tree species in the landscape and offers a cost-effective and pragmatic strategy for soil and vegetation management for farmers.

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The Benefits and Potential Risks of Woody Legume Introductions

Cited by 42 publications

References 32 publications

Nodule Symbiosis of Invasive Mimosa pigra in Australia and in Ancestral Habitats: A Comparative Analysis

Nodule Symbiosis of Invasive Mimosa pigra in Australia and in Ancestral Habitats: A Comparative Analysis

Growth of an invasive legume is symbiont limited in newly occupied habitats

Hybrid improved tree fallows: harnessing invasive woody legumes for agroforestry

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