Treesearch

Treeline studies are often motivated by the general assumption that cold distribution limits of the lifeform tree represent a universal biogeographic margin that is particularly sensitive to recent global warming. But the existing body of scientific literature is less consistent and raises more questions than it provides answers. Not only is the rate of treeline advancement in response to rising temperatures poorly understood, but interactions between biotic and abiotic drivers of treeline dynamics, as well as ecological mechanisms behind surprisingly stable treeline positions also remain...

Periodical cicadas live 13 or 17 years underground as nymphs, then emerge in synchrony as adults to reproduce. Developmentally synchronized populations called broods rarely coexist, with one dominant brood locally excluding those that emerge in off years. Twelvemodern 17-year cicada broods are believed to have descended from only three ancestral broods following the last glaciation. Themechanisms by which these daughter broods overcame exclusion by the ancestral brood to synchronously emerge in a different year, however, are elusive. Here, we demonstrate that temporal variation in the...

The use of prescribed fire to reduce the risk of wildfires and maintain or enhance desired ecological conditions is increasing in forests of the Mid-Atlantic region. Accurate estimates of forest carbon (C) dynamics associated with prescribed burning, including net ecosystem productivity (NEP) and time to accumulate the C lost during burns, termed neutral net ecosystem C balance (NECB), as a function of fire intensity and burn intervals would assist fire managers optimize treatment timing while balancing other ecosystem services provided by forests. We quantified forest C dynamics and...

Focus groups with northern Minnesota logging business owners were held in spring 2023 to understand perceived and observed winter weather changes, challenges they may be facing due to any winter weather changes, and strategies they are taking to adapt to changing conditions. These discussions focused on logger perceptions of weather-related changes during the winter logging season over the course of their career, impacts of weather-related changes on harvest productivity, changes in business practices due to weather-related changes, and positive impacts due to winter weather changes. Most...

Fire is complex and can transform forest ecosystems in ways that affect carbon storage, nutrient cycling, and ecosystem recovery. Methods for measuring the visible, aboveground characteristics of fire have substantially progressed in recent decades, but measuring the unseen, belowground effects of fire remains challenging. The increasing intensity and incidence of wildfire, particularly in the western United States, call for better understanding of the effects of fire on all aspects of the environment, including the soil.

Climate change is outpacing the natural migration rates of many tree species in eastern North America. The local climates in which many tree species are naturally found may become unsuitable in the future. This mismatch could reduce forests' ability to provide ecosystem services such as carbon sequestration, wildlife habitat, and forest products. One proactive solution to these challenges is forest assisted migration, the process by which land managers deliberately move trees from native seed sources to other locations within, or even slightly beyond, their current ranges.

Seed banks can provide insight into a forest's past and give land managers valuable information to help them plan for the forest's future. For example, knowing which species may germinate after future fires is valuable, especially when nonnative invasive species in the seed bank could proliferate quickly following disturbances

Mercury (Hg) is a pollutant that bioaccumulates in the food web, leading to health issues in humans and other fauna. Although anthropogenic Hg deposition has decreased over the past 20 years, our watersheds continue to be sources of Hg to downstream communities. Wetlands, especially peatlands in the Boreal Region of the globe, play a vital role in the formation of bioaccumulative methylmercury (MeHg). Few studies have assessed how increases in temperatures such as those that have already occurred and those predicted will influence the hydrologic transport of Hg to downstream communities or...

Forests around the globe are facing unprecedented threats from biotic and abiotic factors that challenge the overall health of ecosystems and potentially contribute to climate warming through positive feedback to atmospheric CO2. Presently, some of the greatest challenges pertain to the rapid spread and resulting tree mortality caused by nonnative forest insects. Increased global trade and more favorable climates due to climate change have facilitated the establishment of non-native forest insects in new areas where conditions were previously unsuitable for their growth and survival. The...

Global environmental change is pushing many socio-environmental systems towards critical thresholds, where ecological systems' states are on the precipice of tipping points and interventions are needed to navigate or avert impending transitions. Flickering, where a system vacillates between alternative stable states, is an early warning signal of transitions to alternative ecological regimes. However, while flickering may presage an ecological tipping point, these dynamics also pose unique challenges for human adaptation. We link an ecological model that can exhibit flickering to a model...