PRODUCTIVITY OF PERMANENT BROMEGRASS PASTURES IN THE PARKLANDS OF THE PRAIRIE PROVINCES

1976 ◽  
Vol 56 (4) ◽  
pp. 829-835 ◽  
Author(s):  
J. LOOMAN

Bromegrass and bromegrass–legume pastures are usually seeded on cleared and broken forest land, or on broken native grassland. In time, these pastures establish equilibrium with the environment and form distinct plant communities in which several native species occur. The productivity of 15- to 35-yr-old cultivated pastures is commonly three to four times that of native grassland or bush-pastures. Under good management, the presence of "weedy" species does not appreciably reduce yields. Weedy species averaged slightly more than 2% in bromegrass pastures yielding 3,340 kg/ha, and 1% in bromegrass–legume pastures yielding 4,400 kg/ha in 1975.

2013 ◽  
Vol 6 (1) ◽  
pp. 147-160 ◽  
Author(s):  
Cassandra M. Setter ◽  
Rodney G. Lym

AbstractFlea beetles (Aphthona spp.) were released in the Little Missouri National Grasslands (LMNG) in western North Dakota in 1999 to control leafy spurge. The changes in leafy spurge density and soil seedbank composition were evaluated on two ecological sites 10 yr (2009) after Aphthona spp. release to monitor the effectiveness of the insects on weed control and the associated changes in plant communities. In 2009, leafy spurge stem density averaged 2 and 9 stems m−2 (0.19 to 0.84 ft−2) in the loamy overflow and loamy sites, respectively, compared with 110 and 78 stems m−2, respectively, in 1999. Leafy spurge constituted nearly 67% of the loamy overflow seedbank in 1999, compared with 2% in 2009. In the loamy seedbank, the weed represented nearly 70% in 1999, compared with approximately 15% in 2009. As leafy spurge abundance was reduced, native species richness and seed count increased 10 yr after Aphthona spp. release. Late seral species represented 17% of the loamy overflow seedbank in 2009, an increase from 5% in 1999. However, Kentucky bluegrass, a nontarget weedy species, increased more than 250% in the loamy overflow seedbank. Late seral species were 38% of the loamy seedbank in 2009, compared with 13% in 1999. The number of native species increased from 31 in 1999 to 39 in 2009 in the loamy overflow seedbank, but only changed from 32 to 34 species in the loamy site during the same period. The reestablishment of native species has been slow, but seedbank analysis indicates the number and type of species found before the leafy spurge infestation have increased. Planting native species in selected areas may have reduced the lag time in these species return to the seedbank and reduced invasion from other nondesirable species, such as Kentucky bluegrass.


2021 ◽  
Author(s):  
Laura del Rio-Hortega ◽  
Irene Martín-Forés ◽  
Isabel Castro ◽  
José M. de Miguel ◽  
Belén Acosta-Gallo

Associated with the introduction of exotic species in a new area, interactions with other native species within the recipient community occur, reshaping the original community and resulting in a unique assemblage. Yet, the differences in community assemblage between native and invaded ranges remain unclear. Mediterranean grasslands provide an excellent scenario to study community assembly following transcontinental naturalisation of plant species. Here we compared the community resemblance of plant communities in Mediterranean grasslands from both the native (Spain) and invaded (Chile) ranges. We used a novel approach based on network analysis applied to co-occurrence analysis in plant communities, allowing us to study the coexistence of native and alien species in central Chile. This useful methodology is presented as a step forward in invasion ecology studies and conservation strategies. We found that community structure differed between the native and the invaded range, with naturalised species displaying more significant interactions and playing a key role within the invaded community. In addition, alien species displayed positive interactions among them within the communities in the invaded range. Alien species acting like keystones within the Chilean grassland communities might exacerbate the threat posed by biological invasions for the native biodiversity assets. We suggest controlling the spread of the alien species identified as keystones and developing early detection strategies in surrounding areas as management guidelines.


Author(s):  
Elizabeth M. Wandrag ◽  
◽  
Jane A. Catford ◽  
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...  

The introduction of species to new locations leads to novel competitive interactions between resident native and newly-arriving non-native species. The nature of these competitive interactions can influence the suitability of the environment for the survival, reproduction and spread of non-native plant species, and the impact those species have on native plant communities. Indeed, the large literature on competition among plants reflects its importance in shaping the composition of plant communities, including the invasion success of non-native species. While competition and invasion theory have historically developed in parallel, the increasing recognition of the synergism between the two themes has led to new insights into how non-native plant species invade native plant communities, and the impacts they have on those plant communities. This chapter provides an entry point into the aspects of competition theory that can help explain the success, dominance and impacts of invasive species. It focuses on resource competition, which arises wherever the resources necessary for establishment, survival, reproduction and spread are in limited supply. It highlights key hypotheses developed in invasion biology that relate to ideas of competition, outlines biotic and abiotic factors that influence the strength of competition and species' relative competitive abilities, and describes when and how competition between non-native and native plant species can influence invasion outcomes. Understanding the processes that influence the strength of competition between non-native and native plant species is a necessary step towards understanding the causes and consequences of biological invasions.


2019 ◽  
Vol 12 (1) ◽  
pp. 204 ◽  
Author(s):  
Yang Cao ◽  
Yosihiro Natuhara

Riparian areas are local hot spots of biodiversity that are vulnerable and easily degraded. Comparing plant communities in habitats with different degrees of urbanization may provide valuable information for the management and restoration of these vulnerable habitats. In this study, we explored the impact of urbanization on vegetation communities between artificial and semi-natural habitats within two rivers with different levels of development. We compared species richness, types of vegetation, and composition patterns of the plants in our study. In artificial habitats, the sites with relatively high levels of urbanization had the highest species richness, while in semi-natural habitats, the highest species richness was recorded in the less urbanized sites. Furthermore, every component of urbanization that contributed to the variation of species richness was examined in the current study. In artificial habitats, the proportion of impervious surface was the strongest predictor of the variation in species richness and was associated with the richness of alien, native, and riparian species. In semi-natural habitats, most of the richness of alien and native species were associated with the distance to the city center, and the number of riparian and ruderal species was significantly related to the proportion of impervious surface. Moreover, we found that a high level of urbanization was always associated with a large abundance of alien and ruderal species in both artificial and in semi-natural habitats. We recommend the methods of pair comparison of multiple rivers to analyze the impact of urbanization on plant species in riparian areas and have suggested various management actions for maintaining biodiversity and sustainability in riparian ecosystems.


2012 ◽  
Vol 34 (2) ◽  
pp. 219 ◽  
Author(s):  
Megan K. Good ◽  
Jodi N. Price ◽  
Peter J. Clarke ◽  
Nick Reid

Clearing of native vegetation and changes to disturbance regimes have resulted in dense regeneration of native trees and shrubs in parts of Australia. The conversion of open vegetation to dense woodlands may result in changes to the composition of plant communities and ecosystem function if structure, composition and function are tightly linked. Widespread clearing of the floodplain tree Eucalyptus coolabah subsp. coolabah (coolibah), in New South Wales, Australia, has led to state and federal listings of coolibah woodland as an endangered ecological community. Dense regeneration of coolibah in the mid 1970s, however, also resulted in its listing as an ‘invasive native species’ in NSW, meaning it can be legally cleared under certain conditions. Dense regeneration could be a novel state dissimilar to the threatened community or it could represent the next generation of coolibah woodlands and may contribute to passive restoration of heavily cleared landscapes. This study investigated if dense stands are distinct from remnant woodland by comparing floristic composition of the ground-storey community and top-soil properties of four coolibah vegetation states: derived grassland, derived degraded grassland, dense regeneration and remnant woodland. Ground-storey composition was found to overlap broadly among states regardless of tree density. Most species were common to all states, although dense regeneration contained characteristic woodland species that were absent from grasslands. The carbon : nitrogen ratio of the soil was significantly higher in dense regeneration and remnant woodland than in either of the grassland states, indicating that the woody states are broadly similar in terms of nutrient cycling. The study demonstrates that structurally different vegetation states (grasslands, woodlands and dense regeneration) are not associated with distinct plant communities. The results also suggest that grazing management has a more pronounced effect on ground-storey composition of plant communities than tree density and that well managed derived grasslands and dense regeneration are floristically similar to remnant woodlands. Since dense regeneration and remnant woodlands are not floristically distinct from one another, dense regeneration could contribute to the conservation of endangered coolibah woodlands in cleared agricultural landscapes.


Insects ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 773
Author(s):  
Marie Zakardjian ◽  
Benoît Geslin ◽  
Valentin Mitran ◽  
Evelyne Franquet ◽  
Hervé Jourdan

Land-use changes through urbanization and biological invasions both threaten plant-pollinator networks. Urban areas host modified bee communities and are characterized by high proportions of exotic plants. Exotic species, either animals or plants, may compete with native species and disrupt plant–pollinator interactions. These threats are heightened in insular systems of the Southwest Pacific, where the bee fauna is generally poor and ecological networks are simplified. However, the impacts of these factors have seldom been studied in tropical contexts. To explore those questions, we installed experimental exotic plant communities in urban and natural contexts in New Caledonia, a plant diversity hotspot. For four weeks, we observed plant–pollinator interactions between local pollinators and our experimental exotic plant communities. We found a significantly higher foraging activity of exotic wild bees within the city, together with a strong plant–pollinator association between two exotic species. However, contrary to our expectations, the landscape context (urban vs. natural) had no effect on the activity of native bees. These results raise issues concerning how species introduced in plant–pollinator networks will impact the reproductive success of both native and exotic plants. Furthermore, the urban system could act as a springboard for alien species to disperse in natural systems and even invade them, leading to conservation concerns.


Botany ◽  
2010 ◽  
Vol 88 (9) ◽  
pp. 787-809 ◽  
Author(s):  
Hyeok Jae Choi ◽  
J. Hugo Cota-Sánchez

The taxonomy, rarity, and conservation status of Allium  L. is revised for the Canadian prairie provinces, based on analyses of herbarium specimens and fieldwork. Five species are recognized: Allium schoenoprasum  L., A. geyeri S. Watson var. tenerum M.E. Jones, A. textile A. Nelson & J.F. Macbride, A. cernuum Roth, and A. stellatum Ker Gawler. Distribution maps and a key to species are provided, as well as complete descriptions of the species examined, including new illustrations, information on nomenclatural types, synonymies, and chromosomal and ecological data. A lectotype is designated for A. geyeri var. tenerum. In this study, A. geyeri var. geyeri reported from Alberta and Saskatchewan and ranked in these provinces as having rarity levels S2 and S1, respectively, by the Nature Conservancy, is excluded from the Canadian flora and the rare list of these provinces because it was misidentified from a herbarium specimen of A. textile. Allium tricoccum Solander in W. Aiton is regarded as a non-native species to Manitoba. The rarity and conservation status of Allium in the Canadian prairie provinces is as follows: (i) A. schoenoprasum, listed as S2 in Saskatchewan, is rare in Manitoba, although its rarity status has not been formally assessed in the province; (ii) A. geyeri var. tenerum is the rarest Allium taxon, with distribution restricted to the Waterton Lakes National Park areas of Alberta, and is currently listed as S2; and (iii) A. cernuum was re-evaluated and a rarity level of S1S2 was recommended for the species in Saskatchewan, particularly in its southwestern distributional habitat.


2010 ◽  
Vol 3 (2) ◽  
pp. 155-168 ◽  
Author(s):  
Travis L. Almquist ◽  
Rodney G. Lym

AbstractAminopyralid efficacy on Canada thistle (Cirsium arvense) and potential to injure native species was evaluated in a restored prairie at the Glacial Ridge Preserve managed by The Nature Conservancy in Polk County, MN. Canada thistle stem density was reduced from 17 to 0.1 stems m−2 10 mo after treatment (MAT) with aminopyralid applied in the fall at 120 g ha−1. Aminopyralid also altered the composition of both Canada thistle–infested and native plant communities. Aminopyralid controlled Canada thistle and removed or reduced several undesirable forb species from the restored prairie communities, such as absinth wormwood (Artemisia absinthium) and perennial sowthistle (Sonchus arvensis). A number of high seral forbs were also reduced or removed by aminopyralid, including maximilian sunflower (Helianthus maximiliani) and purple prairie clover (Dalea purpurea). Foliar cover of high seral forbs in the native plant community was reduced from 12.2 to 7% 22 MAT. The cover of high seral grass species, such as big bluestem (Andropogon gerardii) and Indiangrass (Sorghastrum nutans) increased after aminopyralid application in both the Canada thistle–infested and native plant communities and averaged 41.4% cover compared with only 19.4% before removal of Canada thistle. Species richness, evenness, and diversity were reduced after aminopyralid application in both Canada thistle–infested and native plant communities. However, the benefits of Canada thistle control, removal of undesirable species, and the increase in native grass cover should lead to an overall improvement in the long-term stability and composition of the restored prairie plant community, which likely outweigh the short-term effects of a Canada thistle control program.


2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Jacinda R Dromgold ◽  
Caragh G Threlfall ◽  
Briony A Norton ◽  
Nicholas S G Williams

Abstract Green roofs are increasingly promoted for urban biodiversity conservation, but the value of these novel habitats is uncertain. We aimed to test two hypotheses: (i) green roofs can support comparable invertebrate family and order richness, composition and abundances to ground-level habitats and (ii) green roofs planted with native species from local habitats will support a richer invertebrate community at family and order level than other green roofs. We sampled the invertebrate community on green roofs dominated by native grassland or introduced succulent species in Melbourne, Australia, and compared these to the invertebrate community in ground-level sites close by, and sites with similar vegetation types. The only significant differences between the invertebrate communities sampled on green roofs and ground-level habitats were total abundance and fly family richness, which were higher in ground-level habitats. Second hypothesis was not supported as invertebrate communities on green roofs supporting a local vegetation community and those planted with introduced Sedum and other succulents were not detectably different at family level. The per cent cover of green space surrounding each site was consistently important in predicting the richness and abundance of the invertebrate families we focussed on, while roof height, site age and size were influential for some taxa. Our results suggest that invertebrate communities of green roofs in Melbourne are driven largely by their surrounding environment and consequently the effectiveness of green roofs as invertebrate habitat is highly dependent on location and their horizontal and vertical connection to other habitats.


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