Can root traits predict communities of soil nematodes in restored northern prairies?

Plant and Soil - We examined how restoration affects the structure and function of grasslands belowground by relating changes in the morphology and architecture of root systems of dominant plants...     

Legacies of afforestation on soil nematode community composition,structure, and diversity in a northern Canadian prairie

Plant and Soil - We examined how legacies of afforestation affect soil food webs using the composition, structure, and diversity of soil nematode communities along a prairie restoration...     

Covariance between disturbance and soil resources dictates the invasibility of northern fescue prairies

Increasing environmental impacts of exotic organisms have refocused attention on the ability of diverse communities to resist biological invaders. Although resource availability, often related to natural and anthropogenic disturbances, appears central to the invasibility of biological communities, understanding the links between resources, diversity and invasibility is often confounded by the covariance among key variables. To test the hypothesis that community invasibility remains contingent on the type and intensity of disturbance and their impacts on plant community diversity and resource availability, we designed an experiment testing the invasibility of northern fescue prairies by smooth brome (Bromus inermis Leyss.), a Eurasian perennial grass, threatening the structure and function of prairie remnants throughout the Great Plains. Using soil disturbances and herbicide, we imposed treatments manipulating the diversity and resource availability of native prairies. Our observations demonstrate that the vulnerability of native prairies to exotic plant invasions remains contingent on resources. While the establishment of smooth brome seedlings increased with increasing disturbance, its impact depended on the availability of soil nitrogen. As a result, soil burial treatments, simulating disturbance by northern pocket gophers, provided poor recruitment areas for smooth brome, and their low levels of soil moisture and nitrogen, combined with the rapid recovery of the prairie community, compromised seedling establishment. Emphasizing the covariance of diversity and key environmental variables following disturbance, our findings illustrate the importance of disturbance type and intensity on community invasibility. Such a consideration is critical in the conservation and restoration of native prairie remnants throughout the Great Plains.     

Importance of species diversity in the revegetation of Alberta’s northern fescue prairies

Restoration of grassland ecosystems is critical to the provision of ecosystem services, however, legacies of historic disturbances pose a challenge to grassland restoration. In the northern Great Plains of North America, continued fragmentation and disturbance of northern fescue prairies has prompted more stringent criteria to regulate the revegetation of native prairies disturbed by industrial activities. Here, we evaluate methods of revegetating northern fescue prairies, disturbed by energy development, and test the hypothesis that higher richness of species seeded within disturbed areas improves the structure, diversity, and composition of revegetated communities. Our results demonstrate that disturbed northern fescue prairies are able to recover their structural elements, including vegetative and ground cover and plant litter, irrespective of the number of species in the seed mixes, even though revegetated areas remained similar in all measures of community diversity. Despite this, revegetated areas remained compositionally different from adjacent native prairies, 7 years following seeding treatments. Based on our observations, the persistent differences in the species composition of disturbed and undisturbed prairies highlight that all efforts should be practiced to minimize the scale of disturbance of northern fescue prairies through energy development.     

Clonal integration facilitates the proliferation of smooth brome clones invading northern fescue prairies

Predicting exotic invaders and reducing their impacts on the biodiversity and function of native ecosystems require understanding of the mechanisms that facilitate their success during key stages of invasion. We determined whether clonal growth, characteristic of the majority of successful invaders of natural areas, facilitates the proliferation of Bromus inermis (smooth brome), an exotic grass invading prairie ecosystems across the Great Plains. By manipulating the below-ground connections of proliferating rhizomes as well as the levels of soil nitrogen along the margins of clones invading northern fescue prairies in Manitoba, Canada, we hypothesized that physiological integration would most benefit ramets invading low resource environments. Severing clonal connections reduced the mass of smooth brome shoots invading native prairies and was exacerbated by the immobilization of soil nutrients with glucose. Clonal connections were equally important in the maintenance of smooth brome density and the horizontal proliferation of ramets. Our results demonstrate the role of physiological integration in the proliferation of a clonal exotic invader and may help explain the success of clonal invaders in other regions. Although integration among invading ramets suggests several possibilities for successful management, future research must continue to elucidate differences in the invasiveness of native versus exotic species as well as the persistence of clonal connections among exotic invaders.     

Invasion or retreat? The fate of exotic invaders on the northern prairies, 40?years after cattle grazing

Despite the detrimental impacts of invasive plants on native biodiversity, ecosystem function, and management cost, few studies have focused on the long-term persistence of invaders. Here, we use a unique, long-term dataset to examine the recovery of northern rough fescue prairie communities, 41?years after the removal of livestock from Riding Mountain National Park, Manitoba, Canada. Our 1973 data suggest that summer grazing of plains?? rough fescue (Festuca hallii (Vasey) Piper) leads to its displacement from the plant community and increased dominance by exotic invaders. After 41?years of recovery time, historic grazing intensity remained an excellent predictor of community structure and composition. Areas classified as heavily grazed in 1973 remained characterized by exotic grasses and had significantly lower richness and diversity. While some exotic invaders persisted despite 41?years of community recovery, others were ephemeral. For example, both Poa pratensis (L.) and Bromus inermis (Leyss.) persisted, increasing in abundance across all classes of grazing intensity, suggesting that their control requires active restoration of the invaded areas. In contrast, passive restoration may be possible for a subset of ephemeral exotic species such as Taraxacum officinale, which had virtually disappeared from invaded prairies by 2010. Our long-term data provide a rare perspective into the long-term dynamics of plant invasions. Based on our findings, conservation managers will need to consider the dichotomy between persistent and ephemeral invaders and their impact on the recovery of northern prairie communities as they focus their restoration efforts against the mounting impacts of exotic plant invaders.