Exotic plant invasion and understorey species richness: a comparison of two types of eucalypt woodland in agricultural Western Australia

1998 ◽  
Vol 4 (1) ◽  
pp. 21 ◽  
Author(s):  
Max Abensperg-Traun ◽  
Lyn Atkins ◽  
Richard Hobbs ◽  
Dion Steven
Keyword(s):  
Species Richness ◽  
Exotic Species ◽  
Plant Species ◽  
Plant Invasion ◽  
Native Plants ◽  
Exotic Plants ◽  
Exotic Plant ◽  
Native Plant ◽  
Road Verge ◽  
Exotic Plant Invasion

Exotic plants are a major threat to native plant diversity in Australia yet a generic model of the invasion of Australian ecosystems by exotic species is lacking because invasion levels differ with vegetation/soil type and environmental conditions. This study compared relative differences in exotic species invasion (percent cover, spp. richness) and the species richness of herbaceous native plants in two structurally very similar vegetation types, Gimlet Eucalyptus salubris and Wandoo E. capillosa woodlands in the Western Australian wheatbelt. For each woodland type, plant variables were measured for relatively undisturbed woodlands, woodlands with >30 years of livestock grazing history, and woodlands in road-verges. Grazed and road-verge Gimlet and Wandoo woodlands had significantly higher cover of exotic species, and lower species richness of native plants, compared with undisturbed Gimlet and Wandoo. Exotic plant invasion was significantly greater in Gimlet woodlands for both grazed (mean 78% cover) and road-verge sites (mean 42% cover) than in comparable sites in Wandoo woodlands (grazed sites 25% cover, road-verge sites 19% cover). There was no significant difference in the species richness of exotic plants between Wandoo and Gimlet sites for any of the three situations. Mean site richness of native plants was not significantly different between undisturbed Wandoo and undisturbed Gimlet woodlands. Undisturbed woodlands were significantly richer in plant species than grazed and road-verge woodlands for both woodland types. Grazed and road-verge Wandoo sites were significantly richer in plant species than communities in grazed and road-verge Gimlet. The percent cover of exotics was negatively correlated with total (native) plant species richness for both woodland types (Wandoo r = ?0.70, Gimlet r = ?0.87). Of the total native species recorded in undisturbed Gimlet, 83% and 61% were not recorded in grazed and road-verge Gimlet, respectively. This compared with 40% and 33% for grazed and road-verge Wandoo, respectively. Grazed Wandoo and grazed Gimlet sites had significantly fewer native plant species than did road-verge Wandoo and road-verge Gimlet sites. Ecosystem implications of differential invasions by exotic species, and the effects of grazing (disturbance) and other factors influencing susceptibility to exotic plant invasion (landscape, competition and allelopathy) on native species decline are discussed. Exclusion of livestock and adequate methods of control and prevention of further invasions by exotic plants are essential requirements for the conservation of these woodland systems.

scholarly journals Agricultural land use curbs exotic invasion but sustains native plant diversity at intermediate levels

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
E. Pellegrini ◽  
M. Buccheri ◽  
F. Martini ◽  
F. Boscutti
Keyword(s):  
Land Use ◽  
Species Richness ◽  
Exotic Species ◽  
Plant Invasion ◽  
Agricultural Land ◽  
Agricultural Land Use ◽  
Exotic Plant ◽  
Land Uses ◽  
Native Plant ◽  
Native Plant Diversity

AbstractUnveiling the processes driving exotic plant invasion represent a central issue in taking decisions aimed at constraining the loss of biodiversity and related ecosystem services. The invasion success is often linked to anthropogenic land uses and warming due to climate change. We studied the responses of native versus casual and naturalised exotic species richness to land uses and climate at the landscape level, relying on a large floristic survey undertaken in North - Eastern Italy. Both climate and land use drove exotic species richness. Our results suggest that the success of plant invasion at this scale is mainly due to warm climatic conditions and the extent of urban and agricultural land, but with different effects on casual and naturalized exotic species. The occurrence of non-linear trends showed that a small percentage of extensive agricultural land in the landscape may concurrently reduce the number of exotic plant while sustaining native plant diversity. Plant invasion could be potentially limited by land management, mainly focusing on areas with extensive agricultural land use. A more consciousness land management is more and more commonly required by local administrations. According to our results, a shift of intensive to extensive agricultural land, by implementing green infrastructures, seems to be a win–win solution favouring native species while controlling the oversimplification of the flora due to plant invasion.

The upland hardwood component of Prince Edward Island's remnant Acadian forest: determination of depth of edge and patterns of exotic plant invasion

2003 ◽  
Vol 81 (11) ◽  
pp. 1113-1128 ◽  
Author(s):  
Kate MacQuarrie ◽  
Christian Lacroix
Keyword(s):  
Exotic Species ◽  
Plant Community ◽  
Plant Invasion ◽  
Vascular Plants ◽  
Canopy Cover ◽  
Percent Cover ◽  
Exotic Plant ◽  
Exotic Plant Invasion ◽  
Acadian Forest ◽  
Study Sites

The upland hardwood component of Prince Edward Island's Acadian forest is among the best remaining examples of the precolonial landscape, but it has been severely fragmented during the past 300 years of human use and settlement. Despite the ecological importance of this remnant habitat and its level of fragmentation, there has been no assessment of depth of edge or exotic plant invasion in these areas. Three 300 m long edge–interior transects were established in each of six study sites. Nine 100-m2 circular plots were sampled along each transect at distances from 5.7 to 300 m; one external plot was established at each transect to sample species in adjacent habitats. In each plot, all vascular plants were identified, a visual estimate of percent cover was made, and soil temperature, canopy cover, and tree diameters were measured. An edge–interior plant community gradient was found within these forests; a plant community characteristic of interior conditions was not reached until a distance of more than 120 m from an edge. This suggests that upland hardwood protected areas smaller than 240 m on a side (5.75 ha) are unlikely to include interior habitat, and sites should be greater than 320 m on all sides (10.24 ha) to ensure at least some interior habitat for vascular plants. Invasion by exotic species was found to be more extensive than that reported from other jurisdictions, and innermost (300 m) plots were not free from exotics. Fifteen exotic species were found within the study sites, with Veronica officinalis (common speedwell) and Hieracium lachenalii (hawkweed) being the most invasive, both in terms of distance penetrated and area covered.Key words: Acadian forest, fragmentation, depth of edge, protected area, Veronica, Hieracium.

scholarly journals Environmental factors affecting the success of exotic plant invasion in a wildland-urban ecotone in temperate South America

2019 ◽  
Vol 14 (2) ◽  
pp. 257-274
Author(s):  
Romina Paola Nievas ◽  
Mirian Roxana Calderon ◽  
Marta Matilde Moglia
Keyword(s):  
Soil Moisture ◽  
Environmental Factors ◽  
Environmental Variables ◽  
Anthropogenic Disturbance ◽  
Plant Invasion ◽  
Exotic Plants ◽  
Scaling Analysis ◽  
Exotic Plant ◽  
Factors Affecting ◽  
Exotic Plant Invasion

Urbanization is one of the main causes driving changes in biodiversity patterns and it is regarded as a major threat to native biota. Successful exotic plant invasion depends on invasiveness and invasibility. Invasiveness is related to the characteristics of exotic plants and invasibility to the features of the sites. The objective of this study was to identify the invasibility environmental factors affecting the success of exotic plant invasion in a wildland-urban ecotone of the central region of Argentina (Potrero de los Funes Village, San Luis). Fifty phytosociological inventories were recorded in an area of 700 ha during spring and summer seasons (2013–2015). Abundance-coverage values of plants and environmental variables such as soil characteristics, anthropogenic disturbance, and altitude of the sites were assessed. Soil moisture, electrical conductivity (EC), acidity (pH), organic matter content, and nitrates were determined as part of the soil analysis. A Nonmetric Multidimensional Scaling analysis was used to identify the possible relationship between abundance-coverage of the vegetation and environmental variables. Abundance-coverage of exotic plants was positively influenced by anthropogenic disturbance and nitrate levels, and negatively affected by altitude. However, no significant correlation was found between percentage of exotic plants and pH, EC, or soil moisture. Thus, urbanization and touristic activities influenced the success of exotic plant invasion.

scholarly journals A century of ecosystem change: human and seabird impacts on plant species extirpation and invasion on islands

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2208 ◽  
Author(s):  
Thomas K. Lameris ◽  
Joseph R. Bennett ◽  
Louise K. Blight ◽  
Marissa Giesen ◽  
Michael H. Janssen ◽  
...  
Keyword(s):  
Species Richness ◽  
Exotic Species ◽  
Plant Species ◽  
Plant Communities ◽  
Soil Depth ◽  
Rapid Change ◽  
Ecosystem Change ◽  
Native Plant ◽  
Native Plant Species ◽  
Species Cover

We used 116 years of floral and faunal records from Mandarte Island, British Columbia, Canada, to estimate the indirect effects of humans on plant communities via their effects on the population size of a surface-nesting, colonial seabird, the Glaucous-winged gull (Larus glaucescens). Comparing current to historical records revealed 18 extirpations of native plant species (32% of species historically present), 31 exotic species introductions, and one case of exotic introduction followed by extirpation. Contemporary surveys indicated that native species cover declined dramatically from 1986 to 2006, coincident with the extirpation of ‘old-growth’ conifers. Because vegetation change co-occurred with an increasing gull population locally and regionally, we tested several predictions from the hypothesis that the presence and activities of seabirds help to explain those changes. Specifically, we predicted that on Mandarte and nearby islands with gull colonies, we should observe higher nutrient loading and exotic plant species richness and cover than on nearby islands without gull colonies, as a consequence of competitive dominance in species adapted to high soil nitrogen and trampling. As predicted, we found that native plant species cover and richness were lower, and exotic species cover and richness higher, on islands with versus without gull colonies. In addition, we found that soil carbon and nitrogen on islands with nesting gulls were positively related to soil depth and exotic species richness and cover across plots and islands. Our results support earlier suggestions that nesting seabirds can drive rapid change in insular plant communities by increasing nutrients and disturbing vegetation, and that human activities that affect seabird abundance may therefore indirectly affect plant community composition on islands with seabird colonies.

scholarly journals A century of ecosystem change: human and seabird impacts on plant species extirpation and invasion on islands

2016 ◽  
Author(s):  
Thomas K Lameris ◽  
Joseph R Bennett ◽  
Louise K Blight ◽  
Marissa Giesen ◽  
Michael H Janssen ◽  
...  
Keyword(s):  
Species Richness ◽  
Exotic Species ◽  
Plant Species ◽  
Plant Communities ◽  
Soil Depth ◽  
Rapid Change ◽  
Ecosystem Change ◽  
Native Plant ◽  
Native Plant Species ◽  
Species Cover

We used 116-years of floral and faunal records from Mandarte Island, British Columbia, Canada, to estimate the indirect effects of humans on plant communities via their effects on the population size of a surface-nesting, colonial seabird, the Glaucous-winged gull (Larus glaucescens). Comparing current to historical records revealed 18 extirpations of native plant species (32% of species historically present), 31 exotic species introductions, and one case of exotic introduction followed by extirpation. Contemporary surveys indicated that native species cover declined dramatically from 1986 to 2006, coincident with the extirpation of ‘old-growth’ conifers. Because vegetation change co-occurred with an increasing gull population locally and regionally, we also tested predictions from the hypothesis that the presence and activities of seabirds help to explain those changes. Specifically, we predicted we would observe high nutrient loading and exotic plant species richness and cover on nearby islands with versus without gull colonies as a consequence of competitive dominance in species adapted to high soil nitrogen and trampling. As predicted, we found that native plant species cover and richness were lower, and exotic species cover and richness higher, on islands with versus without gull colonies. In addition, we found that soil carbon and nitrogen on islands with nesting gulls were positively related to soil depth and exotic species richness and cover across plots and islands. Our results suggest that gulls have the potential to drive rapid change in insular plant communities by increasing nutrients and disturbing vegetation. Because human activities have contributed to long-term change in gull populations, our results further suggest compelling, indirect links between human management decisions and plant community composition on islands of the Georgia Basin.

scholarly journals Exotic garden plants partly substitute for native plants as resources for pollinators when native plants become seasonally scarce

Oecologia ◽  
2020 ◽  
Vol 194 (3) ◽  
pp. 465-480
Author(s):  
Michael Staab ◽  
Maria Helena Pereira-Peixoto ◽  
Alexandra-Maria Klein
Keyword(s):  
Plant Species ◽  
Native Plants ◽  
Exotic Plants ◽  
Interaction Networks ◽  
Exotic Plant ◽  
Exotic Plant Species ◽  
Flower Visitor ◽  
Garden Plants ◽  
Flower Visiting ◽  
Plant Pollinator

Abstract Urban green spaces such as gardens often consist of native and exotic plant species, which provide pollen and nectar for flower-visiting insects. Although some exotic plants are readily visited by pollinators, it is unknown if and at which time of the season exotic garden plants may supplement or substitute for flower resources provided by native plants. To investigate if seasonal changes in flower availability from native vs. exotic plants affect flower visits, diversity and particularly plant–pollinator interaction networks, we studied flower-visiting insects over a whole growing season in 20 urban residential gardens in Germany. Over the course of the season, visits to native plants decreased, the proportion of flower visits to exotics increased, and flower-visitor species richness decreased. Yet, the decline in flower-visitor richness over the season was slowed in gardens with a relatively higher proportion of flowering exotic plants. This compensation was more positively linked to the proportion of exotic plant species than to the proportion of exotic flower cover. Plant–pollinator interaction networks were moderately specialized. Interactions were more complex in high summer, but interaction diversity, linkage density, and specialisation were not influenced by the proportion of exotic species. Thus, later in the season when few native plants flowered, exotic garden plants partly substituted for native flower resources without apparent influence on plant–pollinator network structure. Late-flowering garden plants support pollinator diversity in cities. If appropriately managed, and risk of naturalisation is minimized, late-flowering exotic plants may provide floral resources to support native pollinators when native plants are scarce.

scholarly journals Geographical Analysis of the Distribution and Spread of Exotic Plant Species in Grand Teton National Park, Wyoming

1998 ◽  
Vol 22 ◽  
pp. 3-12
Author(s):  
Deborah Kurtz ◽  
Richard Aspinall ◽  
Katherine Hansen
Keyword(s):  
Exotic Species ◽  
Plant Species ◽  
National Park ◽  
National Park Service ◽  
Exotic Plants ◽  
Rare Plants ◽  
Exotic Plant ◽  
Exotic Plant Species ◽  
Grand Teton National Park ◽  
Park Service

The effects of introduced exotic species in natural environments are becoming important issues in conservation biology and natural resource management and recent scientific literature reveals increasing concern regarding the spread of invasive exotic plant species (Allen, 1996; Vitousek et al. 1996; Walker and Smith, 1997). Ecological consequences of these species include increased competition for space, water, and nutrients with native plants (which could result in a decrease in biodiversity), decreased forage quality for native ungulates, and changes in the microenvironments where the establishments took place (Woods, 1997). Sheley et al (1998) list several ecologically and economically detrimental impacts of exotic species. The National Park Service recognizes the need to protect ecosystems from exotic species (National Park Service, 1997) through management based on the ability to predict species distributions and spread, and monitoring in areas that are most susceptible to invasion. Recommended strategies for preventing the spread of exotic species include developing an early warning system to identify and eradicate new infestations of exotic plants in National Parks, and continued inventory and monitoring of exotic plants (National Park Service, 1997). These strategies will be based on assessment of the distribution and spread of exotic plants (National Park Service, 1997) using remote sensing and Geographic Information Systems (GIS) technologies for mapping and monitoring exotic plants, and models to predict the invasiveness and spread of exotic plants. In Grand Teton National Park (GTNP), exotic species are a great concern for park managers (National Park Service, 1997). Of the 1000 species of flowering plants within GTNP, there are also four (possibly five) rare plants that may be threatened as a result of competition with exotics (Wyoming Rare Plant Technical Committee, 1994): Draba borealis (Boreal draba), Epipactis gigantea (Giant helleborine), Lesquerella carinata var. carinata (Keeled bladderpod), Lesquerella paysonni (Payson's bladderpod), and possibly Draba densifolia var. apiculata (Rockcress draba). The continued survival of these sensitive plants in GTNP increases the need for management of exotic plants. GTNP has implemented a classification system for exotic plant species that consists of three priority levels (GTNP, 1997a). Priority 1 species are designated as "noxious" since they are capable of invading natural ecosystems and disrupting or displacing native vegetation. Currently, there are thirteen exotic plant species with a Priority 1 status within GTNP (Table 1 ).

scholarly journals A century of ecosystem change: human and seabird impacts on plant species extirpation and invasion on islands

2016 ◽  
Author(s):  
Thomas K Lameris ◽  
Joseph R Bennett ◽  
Louise K Blight ◽  
Marissa Giesen ◽  
Michael H Janssen ◽  
...  
Keyword(s):  
Species Richness ◽  
Exotic Species ◽  
Plant Species ◽  
Plant Communities ◽  
Soil Depth ◽  
Rapid Change ◽  
Ecosystem Change ◽  
Native Plant ◽  
Native Plant Species ◽  
Species Cover

We used 116-years of floral and faunal records from Mandarte Island, British Columbia, Canada, to estimate the indirect effects of humans on plant communities via their effects on the population size of a surface-nesting, colonial seabird, the Glaucous-winged gull (Larus glaucescens). Comparing current to historical records revealed 18 extirpations of native plant species (32% of species historically present), 31 exotic species introductions, and one case of exotic introduction followed by extirpation. Contemporary surveys indicated that native species cover declined dramatically from 1986 to 2006, coincident with the extirpation of ‘old-growth’ conifers. Because vegetation change co-occurred with an increasing gull population locally and regionally, we also tested predictions from the hypothesis that the presence and activities of seabirds help to explain those changes. Specifically, we predicted we would observe high nutrient loading and exotic plant species richness and cover on nearby islands with versus without gull colonies as a consequence of competitive dominance in species adapted to high soil nitrogen and trampling. As predicted, we found that native plant species cover and richness were lower, and exotic species cover and richness higher, on islands with versus without gull colonies. In addition, we found that soil carbon and nitrogen on islands with nesting gulls were positively related to soil depth and exotic species richness and cover across plots and islands. Our results suggest that gulls have the potential to drive rapid change in insular plant communities by increasing nutrients and disturbing vegetation. Because human activities have contributed to long-term change in gull populations, our results further suggest compelling, indirect links between human management decisions and plant community composition on islands of the Georgia Basin.

scholarly journals Soil Microbes Alter the Diversity-Invasibility Relationship by Promoting a Complementarity Effect on Community Invasion Resistance

2021 ◽  
Author(s):  
Xiao-Yan Wang ◽  
Song Gao ◽  
Tong Chen ◽  
Jiang Wang ◽  
Fei-Hai Yu
Keyword(s):  
Invasive Species ◽  
Species Richness ◽  
Exotic Species ◽  
Plant Communities ◽  
Soil Microbes ◽  
Exotic Plants ◽  
Invasion Resistance ◽  
Native Plant ◽  
Complementarity Effect ◽  
Negative Effect

Abstract Background Soil microbes can affect both the invasiveness of exotic plants and the invasibility of native plant communities, but it still remains unclear whether soil microbes can influence the relationship between native plant diversity and community invasibility.Methods We constructed native plant communities with three levels of species richness (one, three, or six species) in unsterilized or sterilized soil (i.e., with or without soil microbes) and either prevented their invasion by exotic plants or allowed them to be invaded by each of three exotic species (Solidago canadensis, Erigeron canadensis or Symphyotrichum subulatum), which are highly invasive in China. The soils conditioned by the native plant communities that were not invaded by the exotic species were used as soil microbe inocula to test whether species richness-induced differences in soil microbes affected the growth of each of the three invasive species.Results Compared with soils containing microbes, the absence of soil microbes weakened the negative species richness-invasibility relationship, indicating that soil microbes can contribute to higher invasion resistance in more diverse native plant communities. In the presence of soil microbes, the higher invasion resistance of more diverse communities was mainly ascribed to the complementarity effect. However, soil microbes from communities with a higher species richness did not have a stronger negative effect on the growth of any of the three invasive species. Conclusion Soil microbes can alter the diversity-invasibility relationship by promoting the complementarity effect on community invasion resistance. Our results highlight the importance of integrating the role of soil microbes when testing the diversity-invasibility hypothesis.

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