Treesearch

The management of urban forests is a key element of resilience planning in cities across the globe. Urban forests provide ecosystem services as well as other nature-based solutions to 4.2 billion people living in cities. However, to continue to do so effectively, urban forests need to be able to thrive in an increasingly changing climate. Trees in cities are vulnerable to extreme heat and drought events, which are predicted to increase in frequency and severity under climate change. Knowledge of species' vulnerability to climate change, therefore, is crucial to ensure provision of desired...

Habitat loss and non-native species are 2 of the most important factors that influence native species persistence and behaviors globally. The insectivorous Hawaiian hoary bat (Lasiurus semotus) is the only extant terrestrial mammal native to the Hawaiian Islands. Non-native invasive insectivore species, which are potential competitors of bats for prey, may influence hoary bat behavior. The goal of this study was to determine how small-scale suppression of invasive insectivores (rodents, ants, and yellowjacket wasps [Vespula pensylvanica]) influenced bat activity in grasslands and woodlands....

This chapter focuses on emergency response following an initial detection of an invasive plant pest or foreign animal disease (FAD) as well as the regulatory authority utilized to initiate a response. Many emergency responses will be associated with crops and livestock on farms and ranches while others may involve nurseries, forests, wildlife, and exotic animals in various urban and rural locations. The incident command system framework is typically utilized to organize response eforts. Standard response preparedness and mobilization will be discussed with a consideration of the multitude...

Invasive species are a primary threat to biodiversity and are challenging to manage once populations become established in previously unoccupied areas. But removing them is further complicated when invasions occur in continental, mixed-ownership systems. We demonstrate a rare conservation success: the regional-scale removal of an invasive predator – the barred owl (Strix varia) – to benefit the spotted owl (Strix occidentalis) in California. Barred owl site occupancy declined sixfold, from 0.19 to 0.03, following 1 year of removals, and site extinction (0.92) far exceeded colonization...

Long-term forest experiments provide valuable knowledge in managing forests for productivity and other ecosystem services. California’s “Garden of Eden” experiment was established to determine growth potential of Pinus ponderosaplantations in response to intensive cultural treatments. We examined the 20-year growth-response of tree volume to intensive cultural treatments consisting of combinations of herbicide on competing vegetation (H), fertilization (F), and insecticide (I). We found that both H and F treatments synergistically increased tree growth at intermediate and lower-quality...

With the increasing frequency and severity of altered disturbance regimes in dry, western U.S. forests, treatments promoting resilience have become a management objective but have been difficult to define or operationalize. Many reconstruction studies of these forests when they had active fire regimes have documented very low tree densities before the onset of fire suppression. Building on ecological theory and recent studies, we suggest that this historic forest structure promoted resilience by minimizing competition which in turn supported vigorous tree growth. To assess these historic...

Of the > 6000 species of bark beetles (Coleoptera: Curculionidae, Scolytinae), ~ 25 species cause significant amounts of tree mortality in conifer-dominated forests. Several tactics are available to manage bark beetle infestations and to reduce associated levels of tree mortality. Suppression involves short-term tactics designed to address current infestations by manipulating beetle populations and typically includes the use of sanitation harvests, insecticides, semiochemicals, or a combination of these and other treatments. Prevention is designed to reduce the probability and severity of...

Quantifying the responses of forest disturbances to climate warming is critical to our understanding of carbon cycles and energy balances of the Earth system. The impact of warming on bark beetle outbreaks is complex as multiple drivers of these events may respond differently to warming. Using a novel model of bark beetle biology and host tree interactions, we assessed how contemporary warming affected western pine beetle (Dendroctonus brevicomis) populations and mortality of its host, ponderosa pine (Pinus ponderosa), during an extreme drought in the Sierra Nevada, California, United...

Rising global temperatures driven by anthropogenic carbon emissions are creating new challenges for food crop agriculture and forest management around the world. Droughts and other severe weather events are becoming more common and more extreme, causing both chronic stress and acute damage in cultivated and natural plant life, whereas warmer temperatures favor outbreaks of plant diseases and insect pests in many situations. At the same time, growing awareness of the health and environmental risks associated with broad-spectrum chemical pesticides has led crop growers and forest managers to...

The heating of a fuel element representing a vertically oriented living manzanita leaf was computationally investigated. The computational conditions resembled a previous experimental setup where manzanita leaves were exposed to an upward stream of hot gases supplying the convective heating and a radiant panel providing the radiative heating. The simulations confirmed the experimental observations as to what the impact of the heating mode is on ignition. The convection-only and combined convection and radiation modes resulted in ignition and flaming whereas the radiation-only mode did not....