Papers by Susan Galatowitsch
Successful restoration of sedge meadow wetlands is limited by lack of information regarding reint... more Successful restoration of sedge meadow wetlands is limited by lack of information regarding reintroduction of sedge ( Carex ) propagules. While restoration from seed is common for prairie restorations, little is known about the germination characteristics of many wetland plants, including sedges. We present the results of a 2.5-year study on seed germination and viability for five species of Carex common to sedge meadow and prairie pothole wetlands in temperate North America. Seed storage and germination conditions were investigated to determine the optimum combination for maintaining seed viability and stimulating germination rates over time. Seeds were germinated under seven different temperature and three moisture regimes after storage for 4, 10, and 14 months under one of four different storage regimes (drywarm, dry-cold, moist-cold, and wet-cold). The efficacy of short-term wet-cold stratification to stimulate germination of 2.5-year-old seed after long-term dry storage was also investigated. Carex stricta , Carex comosa , and Carex lacustris showed the greatest germination response after wet-cold or moist-cold storage, while Carex lasiocarpa and Carex rostrata showed similar rates of germination after either wet-cold or dry-warm storage. Wet-cold long-term storage was associated with a high level of viability in all five species after 2.5 years. Viability and germination rates were reduced in Carex stricta , Carex comosa , and Carex lasiocarpa after long-term dry-cold storage. Germination rates of seeds stored dry for 2.5 years are not improved by short-term wet-cold treatment in any species tested. Carex seeds should be stored under wet-cold conditions to maintain seed viability over time, thus increasing the likelihood of seeding success for sedge meadow restoration.
Landscape and Urban Planning, 2000
Wetland assessment techniques have generally focused on rapid evaluations of local and site impac... more Wetland assessment techniques have generally focused on rapid evaluations of local and site impacts; however, wetland biodiversity is often in¯uenced both by adjacent and regional land use. Forty wetlands were studied in the Red River Valley (RRV), Southwest Prairie (SWP), and the Northern Hardwood Forest (NHF) ecoregions of Minnesota, USA, to assess the strength of association between local and landscape condition and avian community composition. We examined the relationship between bird assemblages and local and landscape factors (connectedness, isolation, road density, and site impacts). Landscape variables were calculated for three spatial scales at 500 m (79 ha), 1000 m (314 ha), and 2500 m (1963 ha). Connectedness and road density are important measures for predicting bird assemblages in both agricultural ecoregions (SWP and RRV). Connectedness and its relationship with wetland bird assemblages were most pronounced at the larger scale (2500 m), where the largest remnant patches can be discerned. In contrast, road effects on bird assemblages were most pronounced at the smallest scale (500 m). Wetland isolation corresponded to bird community patterns as well, but only in one ecoregion (SWP). In the urbanizing ecoregion (NHF), species richness was considerably lower than elsewhere but community patterns did not correspond to landscape variables. The focus of wetland conservation planning needs to shift from the site scale to the landscape scale to ensure that connection with the regional wetland pattern is accounted for, therefore, affording the best opportunity to successfully maintain wetland avian diversity. #
Seed Rain of Restored and Natural Prairie Wetlands
Wetlands, 2011
In prairie wetland restorations, seeds may be limiting plant recolonization but this has never be... more In prairie wetland restorations, seeds may be limiting plant recolonization but this has never been quantified in the field. We evaluated the seed rain in restored and natural wetlands to determine if seed limitation constrains plant recolonization. We were particularly interested in determining whether Carex species, dominant vegetation of seasonally flooded zones, are seed limited in restorations. We quantified seed
Wetlands, 2008
Although wetland restoration has been a key part of U.S. environmental policy for 20 years (i.e.,... more Although wetland restoration has been a key part of U.S. environmental policy for 20 years (i.e., ''no net loss''), there is little long-term data on restorations to guide planning and assessment. Understanding how restored wetland communities deviate from natural conditions, and how long those deviations persist, can provide important insights into the mechanisms of recovery and improve restoration practice. This study reports the results from a 19-year survey of 37 restored prairie pothole wetlands in northern Iowa, southern Minnesota, and southeastern South Dakota. Complete floristic surveys were performed for each of the wetlands in 1989, 1990, 1991, 2000, and 2007. The accumulation of wetland species across all sites was greatest during the first 12 years after reflooding (14.4 species/year), after which the rate declined to 1.6 species/year. Proximity to natural wetlands and a semi-permanent water regime favored species accumulations during the first 12 years, but changes since then are primarily linked to water regime. Semi-permanent wetlands have experienced fewer major gains and losses in species richness, whereas temporary and seasonal wetlands have been less stable. From 2000 to 2007, extinctions exceeded colonizations in all wetlands, resulting in a convergence of beta diversity. Although 77% of the species considered common to natural wetlands in the region established in these restorations, 70% of those considered infrequent have not. The likelihood that these restorations will eventually support many additional species appears low, given the presence of barriers to recovery, especially the dominance of invasive perennials (e.g., Phalaris arundinacea and Typha angustifolia/x glauca) on all sites and the low colonization efficiency of wet prairie, sedge meadow, and woody perennial species. Management, such as active revegetation of these low efficiency species guilds, particularly sedge meadow and wet prairie perennials, and invasive species control is needed to ensure that restored prairie wetlands support the region's biodiversity. The important barriers to the recovery of prairie pothole restoration: isolation, infrequent flooding, and invasive species, are all factors that do not self-correct over time and need to be addressed during planning by establishing sound practices for initial implementation and longterm vegetation management.
Characteristics of recently restored wetlands in the prairie pothole region
Wetlands, 1996
Abstract Between 1987 and 1991, 1892 prairie potholes were restored in northern Iowa, southern Mi... more Abstract Between 1987 and 1991, 1892 prairie potholes were restored in northern Iowa, southern Minnesota, and southeastern South Dakota by state and federal agencies, most as part of the Conservation Reserve Program. The total area covered by these restored ...
Wetlands, 1999
Diatoms were employed to assess the recovery of northern prairie wetlands restored after drainage... more Diatoms were employed to assess the recovery of northern prairie wetlands restored after drainage. We predicted that diatom species diversity and equitability are lower in restored wetlands than in reference wetlands and that diatom communities are similar among reference wetlands because communities should be relatively stable over time. Conversely, we predicted that diatom communities in restored and reference wetlands differ because species recovery after restoration may be incomplete or unattainable depending on environmental conditions or dispersal limits. Eight undisturbed, unrestored (reference) wetlands were compared to eight wetlands restored after drainage. Diatom communities on artificial substrates were transplanted from restored to reference wetlands and vice versa to test for environmental control and dispersal limits to community composition. Species richness was similar at restored and reference wetlands. Diversity and equitability at restored and reference sites were similar within a sampling period, but diversity and equitability decreased over the growing season in reference sites. Based on multidimensional scaling analyses, restored and reference sites could not be distinguished by species composition either early or late in the season. Transplanted diatom community assemblages became similar to those in the wetlands to which they were transferred, suggesting a strong environmental control over diatom assemblages. Diatoms, as a whole, responded rapidly to environmental conditions; yet, dispersal still may limit some species' re-establishment, while resistance to disturbance may produce little response among other diatom species. Diatoms may have limited utility as ecological indicators in prairie wetlands because of the unique interaction between diatom life history and the cyclic hydrology of prairie wetlands and because diatom community structure is highly variable among reference wetlands.
Plant Ecology formerly `Vegetatio', 2000
The loss of Carex dominated meadows due to agricultural drainage in the previously glaciated midc... more The loss of Carex dominated meadows due to agricultural drainage in the previously glaciated midcontinent of North America has been extensive. The lack of natural Carex recruitment in wetland restorations and the failures of revegetation attempts underscore the need for information on the establishment requirements of wetland sedges. In this study, seedlings of Carex stricta Lam. were planted in three experimental wetlands in east-central Minnesota, USA to investigate the biotic and abiotic environmental limitations to establishment. Seedlings were planted along an elevational water depth gradient to assess the effects of water depth and water level fluctuation on seedling survival and growth. A different water level fluctuation regime was assigned to each of the experimental wetlands to assess seedling tolerance for seasonal water level changes. The effects of seedling planting density and the presence or absence of non-sedge colonizers on seedling survival and growth were also studied. The experiment was followed for three growing seasons. The results of this study indicate that C. stricta seedlings were sensitive to the timing and duration of inundation during the first growing season. Once established, plants tolerated a broad range of seasonal drying and flooding conditions. Seedling and juvenile growth was slowed by non-sedge colonizers during the first two growing seasons, but by the third growing season, C. stricta was able to out-grow all annual and perennial weeds, except the aggressive perennial, Phalaris arundinacea L. The rapid growth of C. stricta plants, once established, indicates that the use of seedlings is a successful method for ͑re͒ introducing this tussock sedge into wetland restorations under a variety of environmental conditions. Comparison with other studies performed under similar conditions suggests that planting of seedlings is a more appropriate method of establishing this species than the use of transplanted rhizomes.
Assessing ecosystem integrity of restored prairie wetlands from species production–diversity relationships
Hydrobiologia, 2001
We assessed ecosystem integrity in restored prairie wetlands in eastern South Dakota, U.S.A., by ... more We assessed ecosystem integrity in restored prairie wetlands in eastern South Dakota, U.S.A., by examining the relationship between and diatom diversity and production. We asked three questions: (1) Is production related to species diversity? (2) Can production-diversity relationships be used to distinguish between restored and reference wetlands with the purpose of assessing ecological integrity? (3) Are production-diversity relationships influenced by
Journal of Applied Ecology, 2002
1. Nutrient enrichment may adversely impact plant species richness in wetlands and enhance their ... more 1. Nutrient enrichment may adversely impact plant species richness in wetlands and enhance their susceptibility to colonization and dominance by invasive species. For North American prairie wetlands, enrichment by nitrate-N (NO 3 -N) from agricultural runoff is thought to contribute to the increasing colonization and dominance of Phalaris arundinacea (reed canary grass), especially during restoration. If true, P. arundinacea might compromise the re-establishment of sedge meadow vegetation on sites reflooded with agricultural drainage water. 2. We tested this hypothesis using a fertilization experiment in wetlands with controlled hydrology. A community mixture comprising 11 species from native sedge meadow was seeded in mesocosms and grown under one of three NO 3 -N levels (0 g m − 2 year − 1 , 12 g m − 2 year − 1 , 48 g m − 2 year − 1 ) with or without P. arundinacea. Above-and belowground biomass were measured after two growing seasons to assess the response of vegetation to NO 3 -N and P. arundinacea treatments. 3. The total shoot biomass of the native community was suppressed in the presence of P. arundinacea at all NO 3 -N levels, but shoot suppression was significantly greater at the highest NO 3 -N dose level (48 g m − 2 ). Shoot growth of the native community was reduced by nearly one-half under these conditions. 4. The total root biomass of the community was also suppressed by P. arundinacea when no NO 3 -N was added. 5. As NO 3 -N increased, the relative abundance (shoot biomass) of native graminoids declined while native forbs increased in communities with and without Phalaris. The most common graminoid, Glyceria grandis , was suppressed by P. arundinacea at all levels, with suppression enhanced at the 48 g m − 2 NO 3 -N level. Three other species were suppressed at the highest NO 3 -N level, in the presence of Phalaris. The two most common forbs, Asclepias incarnata and Sium suave , exhibited a continual increase in growth with NO 3 -N additions along with overall suppression by P. arundinacea. 6. Community diversity and evenness declined with increasing NO 3 -N levels, whether or not P. arundinacea was present. 7. Our results demonstrate that if P. arundinacea is present, the restored sedge meadow community will not achieve levels of abundance that are possible when this species is absent, regardless of NO 3 -N enrichment conditions. 8. At the same time, the increased suppression by P. arundinacea at the 48 g m − 2 NO 3 -N dose level supports the hypothesis that the dominance of this species over the native sedge meadow community is enhanced by NO 3 -N inputs at levels that are common in agricultural landscapes. 9. Our results carry two implications for achieving biodiversity conservation in agricultural landscapes. First, reducing nitrate loads to wetland reserves is essential for minimizing declines in community diversity. Secondly, the use of P. arundinacea for soil conservation and other agri-environmental purposes should be curtailed because of the likelihood of off-site impacts to wetland biodiversity.
Plant Ecology - PLANT ECOL, 1996
How closely the vegetation of restored wetlands resembles that of comparable natural wetlands is ... more How closely the vegetation of restored wetlands resembles that of comparable natural wetlands is a function of the probability of propagules of wetland species reaching reflooded wetlands and how similar environmental conditions in the restored wetland are those in the natural wetlands. Three years after reflooding, we examined the vegetation composition, water level fluctuations, soil organic carbon content, and soil bulk density as well as surface water pH, alkalinity, conductivity, and calcium and magnesium concentrations of 10 restored and 10 natural wetlands. In the restored wetlands, more species of submersed aquatics colonized than were found in natural wetlands, and they rapidly spread to form extensive beds that were larger than those found in natural wetlands. Emergent and wet meadow species in restored wetlands, however, were found in only sparse stands as were a variety of annuals. The vegetation of natural wetlands was predominantly large stands of emergent species. Flu...
Diversity and Distributions, 2007
Rivers are conduits for materials and energy; this, the frequent and intense disturbances that th... more Rivers are conduits for materials and energy; this, the frequent and intense disturbances that these systems experience, and their narrow, linear nature, create problems for conservation of biodiversity and ecosystem functioning in the face of increasing human influence. In most parts of the world, riparian zones are highly modified. Changes caused by alien plants -or environmental changes that facilitate shifts in dominance creating novel ecosystems -are often important agents of perturbation in these systems. Many restoration projects are underway. Objective frameworks based on an understanding of biogeographical processes at different spatial scales (reach, segment, catchment), the specific relationships between invasive plants and resilience and ecosystem functioning, and realistic endpoints are needed to guide sustainable restoration initiatives. This paper examines the biogeography and the determinants of composition and structure of riparian vegetation in temperate and subtropical regions and conceptualizes the components of resilience in these systems. We consider changes to structure and functioning caused by, or associated with, alien plant invasions, in particular those that lead to breached abiotic-or biotic thresholds. These pose challenges when formulating restoration programmes. Pervasive and escalating human-mediated changes to multiple factors and at a range of scales in riparian environments demand innovative and pragmatic approaches to restoration. The application of a new framework accommodating such complexity is demonstrated with reference to a hypothetical riparian ecosystem under three scenarios: (1) system unaffected by invasive plants; (2) system initially uninvaded, but with flood-generated incursion of alien plants and escalating invasion-driven alteration; and (3) system affected by both invasions and engineering interventions. The scheme has been used to derive a decision-making framework for restoring riparian zones in South Africa and could guide similar initiatives in other parts of the world.
Differences in wetland plant community establishment with additions of nitrate-N and invasive species (<i>Phalaris arundinacea </i>and <i>Typha</i> ×<i>glauca</i>)
Canadian Journal of Botany, 2001
Page 1. Differences in wetland plant community establishment with additions of nitrate-N and inva... more Page 1. Differences in wetland plant community establishment with additions of nitrate-N and invasive species (Phalaris arundinacea and Typha ×glauca)1 Emily K. Green and Susan M. Galatowitsch Abstract: Restored prairie ...
Biological Conservation, 2009
Scenario planning should be an effective tool for developing responses to climate change but will... more Scenario planning should be an effective tool for developing responses to climate change but will depend on ecological assessments of broad enough scope to support decision-making. Using climate projections from an ensemble of 16 models, we conducted an assessment of a midcontinental area of North America (Minnesota) based on a resistance, resilience, and facilitation framework. We assessed likely impacts and proposed options for eight landscape regions within the planning area. Climate change projections suggest that by 2069, average annual temperatures will increase 3°C with a slight increase in precipitation (6%). Analogous climate locales currently prevail 400-500 km SSW. Although the effects of climate change may be resisted through intensive management of invasive species, herbivores, and disturbance regimes, conservation practices need to shift to facilitation and resilience. Key resilience actions include providing buffers for small reserves, expanding reserves that lack adequate environmental heterogeneity, prioritizing protection of likely climate refuges, and managing forests for multi-species and multi-aged stands. Modifying restoration practices to rely on seeding (not plants), enlarge seed zones, and include common species from nearby southerly or drier locales is a logical low-risk facilitation strategy. Monitoring ''trailing edge" populations of rare species should be a high conservation priority to support decisionmaking related to assisted colonization. Ecological assessments that consider resistance, resilience, and facilitation actions during scenario planning is a productive first step towards effective climate change planning for biodiversity with broad applicability to many regions of the world.
Journal of Aquatic Ecosystem …, 1998
Monitoring wetland recovery requires assessment tools that efficiently and reliably discern ecosy... more Monitoring wetland recovery requires assessment tools that efficiently and reliably discern ecosystem changes in response to changes in land use. The biological indicator approach pioneered for rivers and streams that uses changes in species assemblages to interpret degradation levels may be a promising monitoring approach for wetlands. We explored how well metrics based on species assemblages related to land use patterns for eight kinds of wetlands in Minnesota. We evaluated land use on site and within 500 m, 1000 m, 2500 m and 5000 m of riverine, littoral, and depressional wetlands (n = 116) in three ecoregions. Proportion of agriculture, urban, grassland, forest, and water were correlated with metrics developed from plant, bird, fish, invertebrate, and amphibian community data collected from field surveys. We found 79 metrics that relate to land use, including five that may be useful for many wetlands: proportion of wetland birds, wetland bird richness, proportion of insectivorous birds, importance of Carex, importance of invasive perennials. Since very few metrics were significant for even one-half of the wetland types surveyed, our data suggest that monitoring recovery in wetlands with community indicators will likely require different metrics, depending on type and ecoregion. In addition, wetlands within extensively degraded ecoregions may be most problematic for indicator development because biotic degradation is historic and severe.
Plant Ecology, 2004
Invasions by Phalaris arundinacea (reed canarygrass) preclude establishment of sedge meadow veget... more Invasions by Phalaris arundinacea (reed canarygrass) preclude establishment of sedge meadow vegetation in restored wetlands in the midwest USA. To evaluate cover crops as a potential method of P. arundinacea control, we examined the effects of lowering light availability (from 600 to 200 and 10 µmol m −2 s −1 ) on competition between P. arundinacea and a common wetland sedge, Carex hystericina (porcupine sedge), in a greenhouse experiment. Lowering light availability substantially reduced P. arundinacea total biomass, by 52% at 200 µmol m −2 s −1 and by 99% at 10 µmol m −2 s −1 . However, shade also reduced C. hystericina total biomass, by 62% at 200 µmol m −2 s −1 and by 99% at 10 µmol m −2 s −1 . Further, shade did not favor C. hystericina in competition with P. arundinacea. Instead, C. hystericina biomass was reduced significantly more by competition with P. arundinacea in partial shade than in full sun (by 69% compared to 58%), while P. arundinacea biomass was reduced significantly less by competition with C. hystericina in partial shade than in full sun (by 42% compared to 66%). Lowering light availability with a cover crop in restored prairie pothole wetlands might slow P. arundinacea invasion, but is unlikely to improve sedge meadow establishment.
Applying Ecological Principles to Land Management, 2001
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Papers by Susan Galatowitsch