Treesearch

Fire and fuel management is a high priority in North American sagebrush ecosystems where the expansion of pinon and juniper trees and the invasion of nonnative annual grasses are altering fire regimes and resulting in loss of sagebrush species and habitat. We evaluated 10-yr effects of woody fuel treatments on sagebrush recruitment and plant functional group interactions using Sagebrush Steppe Treatment Evaluation Project data. We used mixed-effects ANOVAs to examine treatment effects on sagebrush density and cover and perennial and annual grass cover in expansion woodlands (prescribed...

Invasive plants are widely spread throughout the forests of the southern United States (US) and are expected to rapidly increase their distributional ranges over the next few decades. Multiple studies have shown that invasive plants pose great challenges to forest regeneration at local spatial scales; however, little is known about how those local-scale impacts of invasive plants may collectively influence forest regeneration at a regional scale. In this study, we hypothesized that invasive plants influence forest regeneration across southern US forests by altering tree seedling and...

Ecosystems are changing in complex and unpredictable ways, and analysis of these changes is facilitated by coordinated, long-term research. Meeting diverse societal needs requires an understanding of what populations and communities will be dominant in 20, 50, and 100 yr. This paper is a product of a synthesis effort of the U.S. National Science Foundation funded Long-Term Ecological Research (LTER) network addressing the LTER core research area of populations and communities. This analysis revealed that each LTER site had at least one compelling story about what their site would look like...

Ecosystems across the United States are changing in complex ways that are difficult to predict. Coordinated long-term research and analysis are required to assess how these changes will affect a diverse array of ecosystem services. This paper is part of a series that is a product of a synthesis effort of the U.S. National Science Foundation’s Long Term Ecological Research (LTER) network. This effort revealed that each LTER site had at least one compelling scientific case study about “what their site would look like” in 50 or 100 yr. As the site results were prepared, themes emerged, and...

Woody plant expansions are altering ecosystem structure and function, as well as fire regimes, around the globe. Tree-reduction treatments are widely implemented in expanding woodlands to reduce fuel loads, increase ecological resilience, and improve habitat, but few studies have measured treatment outcomes over long timescales or large geographic areas. The Sagebrush Treatment Evaluation Project (SageSTEP) evaluated the ecological effects of prescribed fire and cut-and-leave treatments in sagebrush communities experiencing tree expansion in North American cold desert shrublands. We used...

Emerald ash borer (EAB), a wood-boring insect native to Asia and invading North America,has killed untold millions of high-value ash trees that shade streets, homes, and parks and caused significant economic damage in cities of the United States. Local actions to reduce damage include surveillance to find EAB and control to slow its spread. We present a multistage stochastic mixed-integer programming (M-SMIP) model for the optimization of surveillance, treatment, and removal of ash trees in cities. Decision-dependent uncertainty is modeled by representing surveillance decisions and the...

Understanding the complex and unpredictable ways ecosystems are changing and predicting the state of ecosystems and the services they will provide in the future requires coordinated, long-term research. This paper is a product of a U.S. National Science Foundation funded Long Term Ecological Research (LTER) network synthesis effort that addressed anticipated changes in future populations and communities. Each LTER site described what their site would look like in 50 or 100 yr based on long-term patterns and responses to global change drivers in each ecosystem. Common themes emerged and...

Grassland insect diversity in many parts of the world is severely threatened by recent deterioration caused by global change and human activities. Insect species richness and abundance are likely sensitive to grassland degradation because of changes in vegetation structure and microclimates, and yet, our understanding of how diversity of insect community, particularly insect guilds responds to grassland degradation is still limited. Here, we conducted a field experiment to examine the responses of richness and abundance of total insects and different insect guilds along degraded levels...

Although past land use effects on composition and structure are described for many forest types, forested riparian areas have been overlooked. Riparian areas may contain unique species and high species richness, as well as contribute basal leaf-litter resources for aquatic fauna. We asked: Does past land use alter composition in riparian versus upland areas in wet tropical forest? Which vegetation life-forms characterize riparian zones? What is the composition and quantity of leaf-litter in riparian zones compared to uplands? Location Riparian and upland locations in tropical wet forest,...

The collection and analysis of urban forest inventory data has been steadily increasing in recent decades. In addition to typical assessments such as number of trees, size distribution, and species composition, estimates of ecosystem services provide empirical indicators of quantity and monetary value to anthropologic populations. As most urban inventories are sample-based, sources of uncertainty and their magnitude provide important information for judging the reliability of estimated population parameters. Most modern analysis tools provide an indication of uncertainty via a sampling...