Migration and control of purple loosestrife (Lythrum salicaria L.) along highway corridors

The east-west density gradient and the pattern and mode of migration of the wetland exotic, purple loosestrife (Lythrum salicaria L.), were assessed in a survey of populations along the New York State Thruway from Albany to Buffalo to determine if the highway corridor contributed to the spread of this species. During the peak flowering season of late July to early August, individual colonies of purple loosestrife were identified and categorized into three size classes in parallel belt transects consisting of the median strip and highway rights-of-way on the north and south sides of the road. Data were also collected on the presence of colonies adjacent to the corridor and on highway drainage patterns. Although a distinct east-west density gradient existed in the corridor, it corresponded to the gradient on adjacent lands and was greatly influenced by a major infestation at Montezuma National Wildlife Refuge. The disturbed highway corridor served as a migration route for purple loosestrife, but topographic features dictated that this migration was a short-distance rather than long-distance process. Ditch and culvert drainage patterns increased the ability of purple loosestrife to migrate to new wetland sites. Management strategies proposed to reduce the spread of this wetland threat include minimizing disturbance, pulling by hand, spraying with glyphosate, disking, and mowing.Contribution 719 of the National Fisheries Research Center-Great Lakes, US Fish and Wildlife Service, 1451 Green Road, Ann Arbor, Michigan 48105, USA.     

Visitor impact on backcountry campsites in the Great Smoky Mountains

Over the last decade the Great Smoky Mountains National Park (GSMNP) has experienced a tremendous increase in visitation, especially in backcountry camping. In 1976 there were an estimated 117,500 backcountry visitor nights, with a peak of 16,865 visitor nights in April. The high use season extends from March to October. Visitation tends to be concentrated in certain sections of the park and at specific sites. The Appalachian Trail, which includes about 8 percent of the maintained trail mileage, carried 32 percent of the visitor nights in 1976.Campsite disturbance is also concentrated in specific sites and sections of the park. Maximum camping disturbance per km of maintained trail was 3,400 m² for the sites on the Appalachian Trail. Shelter sites have more visitation per site and more total disturbance per site than open campsites, but shelters tend to have less intensive disturbance, such as bare soil, because they concentrate trampling impacts. Visitation levels were strongly correlated with disturbances such as bare soil at open campsites. Visitation was significantly correlated to the number of firepits at shelter sites but not to other types of disturbance. Regressions indicate that for each additional visitor night at a site (annual average), one can expect an additional 9 m² of total disturbance and 1 m²of bare soil. The distance of a site from the nearest road was not significantly correlated with damage or visitation. Elevation was correlated to visitation levels, especially in the case of the shelters. More legal sites and large illegal sites are in mesic forest types. Illegal camping accounted for 10 percent of the total camping disturbance.The data imply that the suggested removal of shelters will require redistribution of visitor use or replacement developments, such as tent platforms, in order to mitigate damage. Zone camping is a possible alternative but presents difficulties because campers may concentrate in certain plant communities and topographic positions.     

Value to wildlife of urban-agricultural parks: a case study from Rome urban area

Urban-agricultural parks could have some advantages to wildlife because of less intensive agricultural procedures, absence of hunting pressure, and reduced human disturbance. In this study, the breeding and wintering bird communities and the small mammal community in an urban-agricultural park of Rome were compared to those of a close urban park and a close agricultural area just outside the city. The aim was to assess the best destination and management of wildlife in natural areas at the urban–rural interface. Richness and diversity of bird communities were higher in the urban-agricultural park. Due to habitat features and probably human disturbances, but not to urbanization, predation, and competition factors, the urban park drastically reduces the abundance of decreasing open-land bird species. Abundance of these species was not significantly different in the urban-agricultural park and in the agricultural area. In the urban-agricultural and urban park, bird and mammal pest species were more abundant than they were in the agricultural area. Regarding decreasing abundance of small mammal species, no significant difference among the study areas was observed. Urban-agricultural park is a better choice than urban park for wildlife. Thus, a higher number of preserved urban natural areas should be devoted to urban-agricultural parks. However, to increase the abundance of open-land species and in general wildlife, a less intensive management of cultivated and pasture patches is necessary.     

Removing Chinese Privet (Ligustrum sinense Lour.) and Establishing Native Plants in a Flooded Riparian Corridor in North‐Central Texas,USA

The objectives of this study were to evaluate the allelopathic effects of Chinese privet (Ligustrum sinense Lour.) extract on native seeds and cuttings and to assess the survivability of native plants in a flooded riparian corridor. Field sites occupied the Trinity River floodplain in southeast Dallas County, Texas. Eight native species were evaluated. They were soapberry, red mulberry, persimmon, elderberry, beautyberry, coralberry, mustang grape, and heartleaf peppervine. From this study, we concluded that:

• Truncating privet at ground level and applying equal parts of glyphosate and water to the stump effectively kills the plant;
• Once removed, privet does not curtail establishment of native plants;
• A 60‐day (d) flood killed most plants, with red mulberry being the most resilient;
• A 1% leaf and berry extract from privet significantly reduced soapberry seed germination; and
• A 1% extract from various parts of privet did not significantly affect root growth from cuttings.

     

Changes in interacting species with disturbance

Human-influenced changes in the diversity and abundance of native wildlife in a southern boreal forest area, which became a national park in 1975, are used to develop working hypotheses for predicting and subsequently measuring the effects of disturbance or restoration programs on groups of interacting species. Changes from presettlement conditions began with early 1900 hunting, which eliminated woodland caribou (Rangifer tarandus) and elk (Cervus elaphus), and reduced moose (Alces alces) to the low numbers which still persist. Increases in white-tailed deer (Odocoileus virginianus), as these other cervid species became less abundant or absent, provided enough alternative food to sustain the system's carnivores until plant succession on previously burned or logged areas also caused deer to decline. With increased competition for reduced food, carnivore species also became less abundant or absent and overexploited some prey populations. The abilities of interacting species to maintain dynamically stable populations or persist varied with their different capacities to compensate for increased exploitation or competition. These relationships suggested a possible solution to the problem of predicting the stability of populations in disturbed systems. For the 1976–1985 period, a hypothesis that the increased protection of wildlife from exploitation in a national park would restore a more diverse, abundant, and productive fauna had to be rejected.     

External threats: the dilemma of resource management on the Colorado River in Grand Canyon National park,USA

The United States Congress established Grand Canyon National Park in 1919 to preserve for posterity the outstanding natural attributes of the canyon cut by the Colorado River. In some cases National Park Service attempts to maintain Grand Canyon's natural environment have been thwarted by activities outside the park. One of the most obvious external threats is Glen Canyon Dam, only 26 km upstream from the park boundary. Constructed in 1963, this gigantic dam has greatly altered the physicochemical and biological characteristics of 446 km of the Colorado River in Grand Canyon National Park. The river's aquatic ecosystem has been greatly modified through the loss of indigenous species and the addition of numerous exotics. We consider this anexotic ecosystem. The riparian ecosystem has been less modified, with addition of a few exotics and no loss of natives—this we consider anaturalized ecosystem.The great dilemma now faced by park managers is that, after 20 years of managing resources along a river controlled by Glen Canyon Dam, the Bureau of Reclamation has proposed major changes in operational procedures for the dam. Scientists and managers from the National Park Service, Bureau of Reclamation, and cooperating federal and state resource management agencies are using a systems analysis approach to examine the impacts of various Colorado River flow regimes on aquatic, riparian, and recreational parameters in the park. This approach will help in the development of management alternatives designed to permit the most efficient use of that river's natural resources without their destruction.     

Ideology and wildlands management: The case of Rondeau Provincial Park,Ontario

This is a critical examination of some of the basic concepts that have guided management of parks and related reserves, often termed wildlands. Study is focussed on Rondeau Provincial Park, Ontario, and on concepts such as wilderness, primeval forest, and the Carolinian forest. Deer culling and other management policies and practices have been based upon the idea that the highly valued sassafras, tulip, and other species of the Carolinian forest are decreasing due to browsing. Field mapping and analysis of historic vegetation records indicate that this trend is not in fact occurring. Historic research also reveals difficulties in defining the Carolinian or other perceived types of forest for management purposes. A major reassessment of ideology and management policy and practice seem to be required in Rondeau and other wildlands. Vague or general concepts such as wilderness or preservation should be strongly complemented and supported by more precise statements of objectives, a learning attitude, and experimentation and research. As a result of the technical uncertainties and value judgments frequently involved, management should also be based upon the expressed preferences and continuing involvement of citizens.     

Conversion of temperate forests into heaths: Role of ecosystem disturbance and ericaceous plants

Fire and logging in nutrient-poor temperate forests with certain ericaceous understory plants may convert the forests into heaths. The process of disturbance-induced heath formation is documented by using examples ofCalluna in western Europe,Kalmia in Newfoundland, andGaultheria (salal) in coastal British Columbia. In a cool, temperate climate, rapid vegetative growth ofCalluna, Kalmia, and salal following disturbance results in increasing organic accumulation (paludification), nutrient sequestration, soil acidification, and allelochemicals. These are thought to be the main reasons to conifer regeneration failure in disturbed habitats. If continuation in forest is a land-use objective, then temperate forests with an ericaceous understory should not be logged unless effective silvicultural methods are devised to control the ericaceous plants and restore forest regeneration. Preharvest vegetation control may be considered as an option. Failure to control the understory plants may lead to a long-term vegetation shift, from forest to heathland, particularly in nutrient-poor sites. Successful methods of controllingKalmia andGaultheria, however, have yet to be developed. While theKalmia- andGaultheria- dominated heathlands are undesirable in Canada and the Pacific Northwest, a wide range ofCalluna heathlands of western Europe are being conserved as natural and seminatural vegetation.     

Phalaris arundinacea L. (Reed canary grass—Gramineae) as a hydrophyte in Essex,Connecticut, USA

After the June 1982 floods in Essex, Connecticut, USA, reseeding for stabilization of exposed pond bottoms and subsequent rebuilding of a dam on the Mill Pond, Essex, CT resulted in rooted, floating aquatic mats ofPhalaris arundinacea L. This required that the site be weed harvested to restore open water. It is suggested that the species not be used to temporarily stabilize pond bottom soils because of its great and unexpected adaptability to aquatic situations.     

Responses of Three Heathland Shrubs to Single or Repeated Experimental Trampling

In the last few decades, trampling has become a cause of major disturbance to natural areas. Trampling can occur regularly either seasonally or throughout the year, or as a single impact depending on a recreational activity or an event. This study, carried out on a coastal heathland in north Brittany (France), was based on the hypothesis that the vegetation response can differ depending on whether the trampling is repeated or due to a single event. The aim was to compare the resistance and the short-term recovery capacity of selected species in coastal heathland communities subjected to a trampling experiment, applied once or five times (with equal total number of passes from 0 to 800). The temporal distribution of the trampling did not affect the response of Erica ciliaris, whereas for Erica cinerea and Ulex gallii, trampling was slightly less damaging when applied once rather than five times. These differences could be linked to the lower resistance and the higher recovery capacity of E. ciliaris, compared with the two other species. This study also emphasized the influence of site location by comparing observations with previous studies. Plant resistance calculated here appeared to be lower than that calculated for a less stressful site. The relationship between plant traits and response to trampling was also investigated. The effects of the different times between disturbance application and observations of the short-term response of woody vegetation to experimental trampling is also discussed.     

A Methodological Approach for Designating Management Zones in Mount Spil National Park, Turkey

/ This study was undertaken to (1) determine the suitability of ecosystems within Mount Spil National Park (Turkey) to human activities by a systematic zoning procedure, and (2) provide the basis for developing sound management strategies based on natural-cultural resource attributes of the park. After assessing natural-cultural resources and human activity requirements, the suitability of three zones (Strict Protection Zone, SPZ; Restricted Use Zone, RUZ; and Recreation and Administration Zone, RAZ) for proposed human activities/land uses was determined in order to maintain ecological sustainability and integrity through a weighting-ranking methodology, based on a grid cell resolution of 1 km x 1 km. Results showed that out of the three management zones, the RUZ in which the recreational activities that do not require physical developments are allowed constituted 82% of the park area as the first priority management zone. The proposed zoning procedure is believed to be a key step to improve management for both the study area and other national parks with the similar landscape features.     

Is this trail too crowded? A choice experiment to evaluate tradeoffs and preferences of park visitors in Garibaldi Park,British Columbia

Large crowds in parks can be a problem for park managers and visitors. However, perceptions of crowding are difficult to measure due to coping mechanisms deployed by park visitors. Furthermore, perceptions of crowding should not be measured in isolation, but rather as part of a suite of conditions that comprise the visitors’ outdoor experience. We used a dichotomous choice experiment with visual images and eight attributes to estimate park users’ utilities associated with their visitor experience in Garibaldi Provincial Park in British Columbia, Canada. Our visual method allowed us to control for background view and compare user preferences on hiking trails with preferences at final destinations. We find that utilities are more sensitive to crowding at viewpoints than to other aspects of the outdoor experience. Thus, visitor satisfaction and crowding perceptions are more likely to be defined by where visitors have these encounters rather than the total number of encounters.     

Paving the Way for Invasive Species: Road Type and the Spread of Common Ragweed (<Emphasis Type="Italic">Ambrosia artemisiifolia</Emphasis>)

Roads function as prime habitats and corridors for invasive plant species. Yet despite the diversity of road types, there is little research on the influence of these types on the spread of invaders. Common ragweed (Ambrosia artemisiifolia), a plant producing large amounts of allergenic pollen, was selected as a species model for examining the impact of road type on the spread of invasive plants. We examined this relationship in an agricultural region of Quebec, Canada. We mapped plant distribution along different road types, and constructed a model of species presence. Common ragweed was found in almost all sampling sites located along regional (97%) and local paved (81%) roads. However, verges of unpaved local roads were rarely (13%) colonized by the plant. A model (53% of variance explained), constructed with only four variables (paved regional roads, paved local roads, recently mown road verges, forest cover), correctly predicted (success rate: 89%) the spatial distribution of common ragweed. Results support the hypothesis that attributes associated with paved roads strongly favour the spread of an opportunistic invasive plant species. Specifically, larger verges and greater disturbance associated with higher traffic volume create propitious conditions for common ragweed. To date, emphasis has been placed on controlling the plant in agricultural fields, even though roadsides are probably a much larger seed source. Strategies for controlling the weed along roads have only focused on major highways, even though the considerable populations along local roads also contribute to the production of pollen. Management prioritizations developed to control common ragweed are thus questionable.     

Influence of Cutting Time on Brush Response: Implications for Herbivory in Linear (Transportation) Corridors

An experiment was conducted to determine the influence the time of brush-cutting can have on plant regrowth and attractiveness to herbivores that browse in linear corridors. The influence of cutting time on leaf flush and senescence, shoot morphometry, and biomass was measured for 3 consecutive years after initial brush-cutting. Results indicate that morphological and phenological attributes of three woody deciduous plants were influenced by the timing of brush-cutting for up to 3 years after initial cutting. Brush-cutting generally stimulated plants to produce larger than normal shoots and delay leaf senescence. The degree to which plants were affected, however, varied with the timing of initial cutting and the species in question. Generally, plants cut later in the year resprouted more vigorously and were taller in the third year after cutting but produced less overall biomass than when cut earlier. In the years following brush-cutting, plants cut earlier flushed leaves earlier in the spring but delayed leaf senescence in the fall when compared to uncut controls. Results of these trials suggest that brush-cutting time influences plant response and several plant attributes known to influence plant attractiveness to moose and other herbivores. We therefore recommend that roadside and railside vegetation management plans consider the influence of cutting time on plant regrowth. Such considerations can ensure that brush is cut to reduce the attractiveness of plant regrowth in these linear corridors, reduce the utilization of such brush by herbivores, and, as such, mitigate collision risk between motorists and herbivores such as moose.     

工业园区土地集约利用评价探讨——以重庆经济技术开发区为例

以科学发展观为指导,对工业园区土地集约利用评价的内涵进行了探索,构建了一套工业园区土地集约利用评价的指标体系,采用协调度模型对工业园区发展现状与理想规划目标值间的协调度进行了测算,并对工业园区土地集约利用状况进行了评价。同时,以重庆经济技术开发区为实证,进行了土地集约利用评价,对提高重庆经济技术开发区土地集约利用水平提出了建议。     

Assessing the Potential Impacts to Riparian Ecosystems Resulting from Hemlock Mortality in Great Smoky Mountains National Park

Hemlock Woolly Adelgid (Adelges tsugae) is spreading across forests in eastern North America, causing mortality of eastern hemlock (Tsuga canadensis [L.] Carr.) and Carolina hemlock (Tsuga caroliniana Engelm.). The loss of hemlock from riparian forests in Great Smoky Mountains National Park (GSMNP) may result in significant physical, chemical, and biological alterations to stream environments. To assess the influence of riparian hemlock stands on stream conditions and estimate possible impacts from hemlock loss in GSMNP, we paired hardwood- and hemlock-dominated streams to examine differences in water temperature, nitrate concentrations, pH, discharge, and available photosynthetic light. We used a Geographic Information System (GIS) to identify stream pairs that were similar in topography, geology, land use, and disturbance history in order to isolate forest type as a variable. Differences between hemlock- and hardwood-dominated streams could not be explained by dominant forest type alone as forest type yields no consistent signal on measured conditions of headwater streams in GSMNP. The variability in the results indicate that other landscape variables, such as the influence of understory Rhododendron species, may exert more control on stream conditions than canopy composition. The results of this study suggest that the replacement of hemlock overstory with hardwood species will have minimal impact on long-term stream conditions, however disturbance during the transition is likely to have significant impacts. Management of riparian forests undergoing hemlock decline should, therefore, focus on facilitating a faster transition to hardwood-dominated stands to minimize long-term effects on water quality.     

Issues and impacts of Redwood National Park expansion

In 1968, Redwood National Park was created in an atmosphere of controversy and compromise to preserve remnants of the coastal redwood (Sequoia sempervirens) ecosystems and the streams and seashores with which they are associated. The 1968 boundary included the lower portions of several watersheds in the park, which meant that potential impacts from upstream, privately owned lands might occur. Between 1968 and 1978, controversy continued between preservation and forest industry interests over the impacts of harvesting old growth timber upslope and upstream from the park. In 1978, the southern portion of the park around Redwood Creek was expanded by 48,000 acres, moving the boundary from a narrow, one-half mile riparian corridor to ridgelines, but still leaving two-thirds of the total watershed outside of the park. The park expansion has generated biological and social impacts and opportunities. Meeting the objectives of the 1978 legislation will require close coordination between federal and state government and local communities.     

Phytoremediation of Copper‐Contaminated Soil Using Helianthus annuus,Brassica nigra,and Lycopersicon esculentum Mill.: A Pot Scale Study

Phytoremediation is an eco‐friendly and cost‐effective technology that uses plants to extract contaminants from the environment or to decrease contaminant toxicity. This article documents a study not only of the effectiveness of copper uptake by Heliantus annuus (common sunflower), Brassica nigra (black mustard), and Lycoperscion esculentum Mill. (a tomato species), but of where, within these plant species, the copper is accumulated—in the roots or in the shoots. This is vital information, for if these particular plants accumulate copper primarily in their roots, then their edible portions will likely be safe to eat, while if they accumulate the copper in their shoots, their harvestable portions would be harmful to living beings.     

Structure of a forested urban park: Implications for strategic management

Informed management of urban parks can provide optimal conditions for tree establishment and growth and thus maximize the ecological and aesthetic benefits that trees provide. This study assesses the structure, and its implications for function, of the urban forest in Allan Gardens, a 6.1 ha downtown park in the City of Toronto, Canada, using the Street Tree Resource Analysis Tool for Urban Forest Managers (STRATUM). Our goal is to present a framework for collection and analysis of baseline data that can inform a management strategy that would serve to protect and enhance this significant natural asset. We found that Allan Garden’s tree population, while species rich (43), is dominated by maple (Acer spp.) (48% of all park trees), making it reliant on very few species for the majority of its ecological and aesthetic benefits and raising disease and pest-related concerns. Age profiles (using size as a proxy) showed a dominance of older trees with an inadequate number of individuals in the young to early middle age cohort necessary for short- to medium-term replacement. Because leaf area represents the single-most important contributor to urban tree benefits modelling, we calculated it separately for every park tree, using hemispheric photography, to document current canopy condition. These empirical measurements were lower than estimates produced by STRATUM, especially when trees were in decline and lacked full canopies, highlighting the importance of individual tree condition in determining leaf area and hence overall forest benefits. Stewardship of natural spaces within cities demands access to accurate and timely resource-specific data. Our work provides an uncomplicated approach to the acquisition and interpretation of these data in the context of a forested urban park.     

Can Land Managers Control Japanese Knotweed? Lessons from Control Tests in Belgium

Japanese knotweed Fallopia japonica is an extremely abundant invasive plant in Belgium and surrounding countries. To date, no eradication method is available for land managers facing the invasion of this rhizomatous plant. We tested different chemical herbicides with two application methods (spraying and stem injection), as well as mechanical treatments, on knotweed clones throughout southern Belgium. The tested control methods were selected to be potentially usable by managers, e.g., using legally accepted rates for herbicides. Stem volume, height and density reduction were assessed after one or two years, depending on the control method. Labor estimations were made for each control method. No tested control method completely eradicated the clones. Stem injection with glyphosate-based herbicide (3.6?kg?ha^?1 of acid equivalent glyphosate) caused the most damage, i.e., no sprouting shoots were observed the year following the injection. The following year, though, stunted shoots appeared. Among the mechanical control methods, repeated cuts combined with native tree transplanting most appreciably reduced knotweed development. The most efficient methods we tested could curb knotweed invasion, but are not likely to be effective in eradicating the species. As such, they should be included in a more integrated restoration strategy, together with prevention and public awareness campaigns.