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Question: Natural areas are commonly managed for multiple purposes, including both conservation and recreational use. Hiking trails are an extremely common feature in natural areas that enable recreational use, but trail construction and use can also facilitate the spread of non‐native species by altering trailside conditions, creating disturbances, and acting as a conduit for non‐native propagules to be carried into the backcountry. Location: Powdermill Nature Reserve, Southwestern Pennsylvania, USA. Methods: We tested how distance from trailhead and trailside affected the understory plant cover and abundance and light and soil environment by establishing study plots at varying distances from the trailhead along perpendicular transects from the trailside. Results: We found that non‐native plant cover decreased with distance from the trailhead, with the majority occurring within 1 km of the trailhead, while non‐native cover increased by as much as 12% moving away from the trailside and toward the forest interior. Total species richness and diversity decreased with increasing distance from the trailhead and per‐species mean cover increased. Total cover decreased in plots with higher light levels. Conclusions: Our results suggest that hiking trails could be acting as a conduit for the spread of non‐native plants, with the greatest effect occurring near the trailhead where early detection and future management efforts could be concentrated. The measurable increase in non‐native cover moving away from the trailside is potentially a result of trails being constructed in an already‐invaded forest, with the effects of trail construction or active management reducing non‐native cover at the immediate trailside.Our study of non‐native species spread along recreational trails in a nature reserve in southwestern Pennsylvania found that non‐native cover was highest near the trailhead, but also higher in the forest interior than at the immediate trailside. We hypothesize that this unexpected result is due to active management of non‐native species by trail users. [ABSTRACT FROM AUTHOR]

Questions: A recently introduced non‐native annual grass, Ventenata dubia, is challenging previous conceptions of community resistance in forest mosaic communities in the Inland Northwest. However, little is known of the drivers and potential ecological impacts of this rapidly expanding species. Here we (1) identify abiotic and biotic habitat characteristics associated with the V. dubia invasion and examine how these differ between V. dubia and other problematic non‐native annual grasses, Bromus tectorum and Taeniatherum caput‐medusae; and (2) determine how burning influences relationships between V. dubia and plant community composition and structure to address potential impacts on Inland Northwest forest mosaic communities. Location: Blue Mountains of the Inland Northwest, USA. Methods: We measured environmental and plant community characteristics in 110 recently burned and nearby unburned plots. Plots were stratified to capture a range of V. dubia cover, elevations, biophysical classes, and fire severities. We investigated relationships between V. dubia, wildfire, environmental, and plant community characteristics using non‐metric multidimensional scaling and linear regressions. Results: Ventenata dubia was most abundant in sparsely vegetated, basalt‐derived rocky scablands interspersed throughout the forested landscape. Plant communities most heavily invaded by V. dubia were largely uninvaded by other non‐native annual grasses. Ventenata dubia was abundant in both unburned and burned areas, but negative relationships between V. dubia cover and community diversity were stronger in burned plots, where keystone sagebrush species were largely absent after fire. Conclusions: Ventenata dubia is expanding the overall invasion footprint into previously uninvaded communities. Burning may exacerbate negative relationships between V. dubia and species richness, evenness, and functional diversity, including in communities that historically rarely burned. Understanding the drivers and impacts of the V. dubia invasion and recognizing how these differ from other annual grass invasions may provide insight into mechanisms of community invasibility, grass‐fire feedbacks, and aid the development of species‐specific management plans. [ABSTRACT FROM AUTHOR]

Questions: In the assessment of a soil seed bank at invaded sites, do sampling at different microsite types and use of different assessment methods yield different results, which may influence interpretation of management effectiveness and potential for native plant restoration? Location: Saguaro National Park, Arizona, United States. Methods: Seed bank samples were collected from two microsite types (below‐shrub canopies and interspaces between perennial plants) at plots within Pennisetum ciliare‐invaded and untreated sites, non‐invaded sites and sites with five frequencies of Pennisetum‐removal treatments. Seed bank samples were characterized by seedling emergence and seed extraction methods. Results: Assay method influenced whether we detected a significant Pennisetum‐removal treatment response on Pennisetum detected in the seed bank. A treatment response was not observed using the emergence method. Using the extraction method, we found that untreated Pennisetum plots contained significantly more Pennisetum seed than removal treatments. Treatments did not affect detection of native seed banks using either method. Microsite type only had an effect on seed detected using the emergence method, where more perennial species and seed densities were detected below shrubs. Native species richness and estimated seed densities using extraction were correlated with emergence results (r = 0.52, N = 42, p < 0.001 and r = 0.56; N = 42, p < 0.001, respectively). Conclusions: Results highlight several considerations for how different seed bank methods can influence interpretation of management treatments. Along with vegetation surveys, seed bank observations indicate that removal treatments successfully reduced Pennisetum in soil seed banks at invaded sites relative to invaded untreated sites. Natives were a significant proportion of seed banks, showing potential for native plants to establish after treatments of non‐native plants. Results suggest potential to calibrate seed bank methods with each other to reconcile differences. Because viability of extracted seed was uncertain, further analysis may be necessary to test which assay method best predicts future vegetation. Seed bank assays are often used to assess vegetation dynamics and conservation activities. We found that seedling emergence and seed extraction results differed for detection of the non‐native perennial grass Pennisetum ciliare (L.) Link (buffelgrass) along a removal treatment gradient. Results suggest that assay methods selected to assess seed banks can influence the interpretation of non‐native plant removal treatments. [ABSTRACT FROM AUTHOR]

Questions Most rivers in the Western Cape Province of South Africa are heavily invaded by alien trees, often resulting in profound changes in biodiversity and ecosystem functioning. Although large-scale management operations are underway to clear invasive trees and restore ecosystem function, little is known regarding native species recovery after alien clearing. Has Eucalyptus invasion along the Berg River altered the distribution and composition of native vegetation? How does the removal of invasive trees through complete clearing and thinning facilitate the recovery of native vegetation? Location Berg River, Western Cape, South Africa. Methods We assessed the recovery of native vegetation after 4 yr of complete clearing of the invasive tree Eucalyptus camaldulensis (100% alien cover removal) and thinning (40-50% alien cover removal) along the Berg River in the Western Cape, South Africa. Native and alien plant cover, species richness and diversity were recorded on completely cleared and thinned sites and compared to natural (non-invaded control sites) and E. camaldulensis invaded sites. Results Species richness and diversity were significantly higher in both completely cleared and thinned sites compared to natural and invaded sites. Increases in species richness and diversity in completely cleared and thinned sites were a result of re-invasion by alien herbaceous and graminoid species, which have the potential to hinder native species recovery. Cover of native trees and shrubs was higher in both completely cleared and thinned sites compared to invaded sites. Species composition (relative cover) in completely cleared and thinned sites was similar to species composition in natural sites. Conclusions Both complete clearing and thinning methods promote indigenous vegetation recovery and a positive trajectory towards recovery of ecosystem structure and composition can be expected in future. To improve management operations, a four-stage thinning process that has the potential to facilitate native species recovery is suggested. [ABSTRACT FROM AUTHOR]

Question Is illegal garden waste dumping in mixed deciduous forests a source for establishment of non-native plants in deciduous forests? Location Northwestern Switzerland. Methods We quantified the amount of illegally dumped garden waste at 20 sites over 1 yr and compared the soil conditions, species richness and abundance of plants in the ground vegetation at disposal sites with those at 20 control sites in urban deciduous forests. Results We found that illegal garden waste dumping frequently occurs in urban forests. At single sites, 0.1-12.5 m3 (mean: 2.6 m3) garden waste was dumped per month, resulting in a total annual amount of 2.2-35.8 m3 (mean: 17.8 m3) waste deposited. Thirty-seven of the 163 plant species recorded were not native to Switzerland. All 37 non-native species were recorded in waste disposal sites, but only three of them in control sites. Thus, garden waste dumping sites harboured a larger number of non-native species than control sites, but the two groups of sites did not differ in number of native species. The species composition also differed between disposal and control sites: larger proportions of species typical of disturbed habitats, more therophytes and species with autochorous seed dispersal were recorded in disposal sites than in control sites. Conclusions We provide evidence that numerous non-native horticultural plant species escape from dumping sites and colonize forests. There is an urgent need to increase awareness of garden owners concerning problems associated with illegal garden waste dumping. [ABSTRACT FROM AUTHOR]