Treesearch

Context The dual threats of habitat fragmentation and climate change have led to a proliferation of approaches for connectivity conservation planning. Corridor analyses have traditionally taken a focal species approach, but the landscape ‘‘naturalness’’ approach of modeling connectivity among areas of low human modification has gained popularity as a less analytically intensive alternative. Objectives We compared focal species and naturalness- based corridor networks to ask whether they identify similar areas, whether a naturalness-based approach is in fact more analytically efficient, and...

Roads and traffic are typically more of a threat to the conservation of birds rather than a safety issue for motorists. Some bird species have biological features and life history traits that make them particularly vulnerable to habitat loss from roads and mortality due to wildlife-vehicle collisions (WVC). Road planning that proactively considers the biological needs of birds will help avoid project delays and extra costs for mitigation, as well as achieve positive outcomes for birds. Several strategies effectively avoid or mitigate the negative effects of roads on birds.

Dam removal is an increasingly practised river restoration technique, and ecological responses vary with watershed, dam and reservoir properties, and removal strategies. Moderate-sized dams, like Hemlock Dam (7.9m tall and 56m wide), are large enough that removal effects could be significant, but small enough that mitigation may be possible through a modified dam removal strategy. The removal of Hemlock Dam in Washington State, USA, was designed to limit channel erosion and improve fish passage and habitat by excavating stored fine sediment and reconstructing a channel in the former 6-ha...

A non-native invasive sawfly, the amber-marked birch leaf miner Profenusa thomsoni (Konow), was first detected in south-central Alaska in 1996 and is now widely distributed throughout urban and wild birch trees in Alaska. Impacts have been considered primarily aesthetic because leaf miners cause leaves of birch trees (Betula spp.) to senesce prematurely, but the leaf miners likely also reduce birch vigour and thereby increase susceptibility to diseases and other insects. We tested the ability of commercially available biological control agents to control P. thomsoni. The entomopathogenic...

Piscivory by birds can be significant, particularly on fish in small streams and during seasonal low flow when available cover from predators can be limited. Yet, how varying amounts of cover may change the extent of predation mortality from avian predators on fish is not clear. We evaluated size-selective survival of coastal cutthroat trout (Oncorhynchus clarkii clarkii) in replicated semi-natural stream sections. These sections provided high (0.01 m2 of cover per m2 of stream) or low (0.002 m2 of cover per m2 of stream) levels of instream cover available to trout and were closed to...

BACKGROUND: Economic and ecological impacts of ash (Fraxinus spp.) mortality resulting from emerald ash borer (EAB) (Agrilus planipennis Fairmaire) invasion are severe in forested, residential and urban areas. Management options include girdling ash trees to attract ovipositing adult beetles and then destroying infested trees before larvae develop or protecting ash with a highly effective, systemic emamectin benzoate insecticide. Injecting this insecticide and then girdling injected trees a few weeks later could effectively create lethal trap trees, similar to a bait-and-kill tactic, if...

Over large areas, synchronous fluctuations in population density are often attributed to environmental stochasticity (e.g., weather) shared among local populations. This concept was first advanced by Patrick Moran who showed, based on several assumptions, that long-term population synchrony will equal the synchrony of environmental stochasticity among locations. We examine the consequences of violating one of Moran's assumptions, namely that environmental synchrony is constant through time. We demonstrate that the synchrony of weather conditions from regions across the United States varied...

Aim We examined species composition of urban forests from local to global scales using occurrence and abundance information to determine how compositional similarity is defined across spatial scales. We predicted that urban forests have become more homogeneous world-wide, which should result in minimal scale dependence that is more pronounced for non-native species, especially when considering abundance information.

Information on street trees is critical for management of this important resource. Sampling of street tree populations provides an efficient means to obtain street tree population information. Long-term repeat measures of street tree samples supply additional information on street tree changes and can be used to report damages from catastrophic events. Analyses of several street tree populations reveal that a 2%-3% sample of block segments with known length within a city will likely produce estimates on the total number of trees with a standard error around 10% of the total population...

Disturbance-dependent habitats such as grasslands and shrublands are declining in many regions. To mitigate these declines, government agencies are using anthropogenic disturbances like logging and mowing to mimic natural ones. Because these programs can be costly or controversial, measuring their effectiveness is important. Here, we evaluate the conservation effectiveness of shrubland management for 15 bird species in Massachusetts, USA. Because shrublands are constantly changing in extent and location, we suggest that the key measure of conservation effectiveness should be how managed...