Search Results (5)

Lake Winona is a 129-hectare urban lake which occupies part of an old side channel of the Mississippi River and has been modified significantly over the past 125 years. The entire shoreline (>8 km) is publicly owned, with current shorelines created mostly during two periods of lake dredging and filling of fringe wetlands 70 and 110 years ago, respectively. Since then, some sections were allowed to revegetate naturally with trees and shrubs, some were armored with riprap, and others have been maintained mostly as turfgrass parklands. Shoreline vegetation assessments and tree stand surveys were completed prior to beginning targeted shoreline rehabilitation in 2017. These rehabilitation activities (encompassing the majority of shoreline) include the following: (1) repeated removal and chemical treatment of woody invasive shrubs/trees (primarily common buckthorn Rhamnus cathartica and nonnative bush honeysuckles Lonicera spp.) by contractors and volunteers; (2) chemical spraying and hand pulling of nonnative invasive ornamental grasses (Miscanthus spp.) and forbs (Japanese hops Humulus japonica; leafy spurge Euphorbia esula) annually or as needed; (3) killing of turfgrass and overseeding with native prairie species; (4) shrub and sapling plantings and overseeding with native species in both wooded and turfgrass sections; (5) installation of wave barriers (using cut woody invasives) and planting of emergent aquatic macrophytes; (6) prescribed burns of prairie plantings; (7) establishment of fixed photo reference points to document changes; and (8) altered park mowing practices to maintain a shoreline buffer of vegetation. These ongoing management activities aim to replace more turfgrass with native prairie, plant more shrubs and trees on shorelines, suppress nonnative invasives, and encourage the development of aquatic macrophyte beds to reduce, or eliminate shoreline erosion. Future management activities will continue to emphasize invasive species control, turfgrass conversion to native vegetation, and shoreline erosion reduction. Full article

This study characterized important environmental factors that contribute to plant invasion in the forested riparian zones surrounding stream restoration sites. We sampled vegetation and environmental variables (light availability, soil physiochemistry, and site age) across invasion gradients at multiple sites in Virginia, USA. Data analysis involved a multimetric statistical approach combining correlation and Canonical Correspondence Analysis (CCA) to arrive at a plausible model for invasion risk by species. We targeted three of the most problematic invaders in these systems: Lespedeza cuneata (sericea lespedeza), Lonicera japonica (Japanese honeysuckle), and Microstegium vimineum (Japanese stiltgrass). Our analysis revealed species-specific environmental drivers of invasion, with certain factors consistently important across all targeted invaders—notably, canopy cover, nitrogen availability, soil texture, and bioavailable phosphorus, as indicated by the importance of certain proxies (e.g., metal cations). The results of this research have been used to develop a suite of best practices that can be implemented at the outset of a stream restoration project to reduce the risk of invasion in the riparian forests surrounding these sites. Full article

Invasive plants decrease biodiversity, modify vegetation structure, and inhibit growth and reproduction of native species. Japanese honeysuckle (Lonicera japonica Thunb.) is the most prevalent invasive vine in the forestlands of eastern Texas. Hence, we aimed to identify potential factors influencing the distribution of the species, quantify the relative importance of each factor, and test possible management strategies. We analyzed an extensive dataset collected as part of the Forest Inventory and Analysis Program of the United States Department of Agriculture (USDA) Forest Service to quantify the range expansion of Japanese honeysuckle in the forestlands of eastern Texas from 2006 to 2011. We then identified potential factors influencing the likelihood of presence of Japanese honeysuckle using boosted regression trees. Our results indicated that the presence of Japanese honeysuckle on sampled plots almost doubled during this period (from 352 to 616 plots), spreading extensively, geographically. The probability of invasion was correlated with variables representing landscape conditions, climatic conditions, forest features, disturbance factors, and forest management activities. Habitats most at risk to invasion under current conditions occurred primarily in northeastern Texas, with a few invasion hotspots in the south. Estimated probabilities of invasion were reduced most by artificial site regeneration, with habitats most at risk again occurring primarily in northeastern Texas. Full article

The conversion of agricultural lands to forests has increased worldwide over the past few decades for multiple reasons including increasing forest connectivity and wildlife habitat. However, previous land cover and competing vegetation often impede afforestation. We established 219 plots in 29 Quercus plantations on four previous land cover types (LCT): Clover, Soybeans, Woody Brush, and Herbaceous Weeds. Plantations were located in Illinois, USA and were sampled 15–18 years after planting. Sampling data for all trees (planted and volunteer) included species, diameter, and vine presence on the main bole of the tree. Free-to-grow status was recorded for all Quercus species and estimated cover of two invasive species, Elaeagnus umbellata and Lonicera japonica, was documented on each plot. There was a strong relationship between total tree density and invasive species cover across all sites. Stocking success was lower and E. umbellata cover was higher on Woody Brush sites compared to Clover and Soybean cover types. Additionally, significantly more free-to-grow Quercus saplings occurred in Clover and Soybean cover types compared to the Woody Brush sites. The results indicate that previous land cover plays a critical role in forest afforestation. Furthermore, while historically, volunteer tree species were thought to be detrimental to the development of planted species these results suggest that with the increasing prevalence of invasive species worldwide the role of volunteer species in afforestation should be reconsidered and silvicultural protocols adjusted accordingly. Full article

Japanese honeysuckle is one of the most aggressive invasive vines in forestlands of the southern United States. We analyzed field data collected by the U.S. Forest Service to identify potential determinants of invasion and to predict likelihood of further invasion under a variety of possible management strategies. Results of logistic regression, which classified 74% of the field plots correctly with regard to species presence and absence, indicated probability of invasion is correlated positively with adjacency to water bodies, temperature, site productivity, species diversity, and private land ownership, and is correlated negatively with slope, stand age, artificial regeneration, distance to the nearest road, and fire disturbance. Habitats most at risk to further invasion under current conditions occur throughout Mississippi, stretching northward across western Tennessee and western Kentucky, westward across southern Arkansas, eastward across north-central Alabama, and also occur in several counties scattered within Virginia. Invasion likelihoods could be increased by global climate change and reduced most by conversion to public land ownership, followed by artificial regeneration, and fire disturbance. While conversion of land ownership may not be feasible, this result suggests the opportunity for decreasing the likelihood of invasions on private lands via using selected management practices. Full article