Treesearch

Data collected by the U.S. Forest Service Forest Inventory and Analysis Program was assembled from each region of the United States. Occurrence, measured as the percentage of forested subplots within a county with observed nonnative invasive plant (NNIP) species, was calculated across the continental United States and Hawaii. Each region, and in some cases each state, maintains a specific watch list to constrain monitoring to only the most important NNIP species within a given area. Therefore, occurrence is based on regionally important species and is inconsistent across the United States....

Invasive plant species have significant negative impacts in many ecosystems and are found in many forests around the world. Although not all introduced species become invasive, there are numerous examples of species escaping cultivation and invading natural ecosystems years or even decades after their initial introduction. Regional distributions of invasive species are influenced by climatic and physical conditions; within the landscape, fragmentation, disturbance, and surrounding land use are important factors. Inventory data can help describe the distribution (reported as constancy) and...

The Southern Research Station (SRS) Forest Inventory and Analysis (FIA) Program began monitoring nonnative invasive plant (NNIP) species in 2001 in response to a growing desire to track potential forest health threats on United States forest land. The SRS-FIA NNIP program has produced significant results and contributed considerably to the understanding of the distribution and spread of NNIP in the southern United States. However, opportunities to improve NNIP monitoring in the South do exist. Specifically, the SRS-FIA program monitors only a select number of NNIP species. Given the...

Alien plants introduced for commercial or landscaping use have caused substantial problems as invaders of natural and managed ecosystems. The magnitude of the problem has dramatically increased over the past few decades with accelerated land disturbance, land use changes, and global and internal transportation. In the southern region of the United States, invasive plants are one of the threats to the long-term sustainability of our forest ecosystems along with climate change and land use change. We assessed the potential distribution of invasive plants in forests of the southern region...

The willingness to accept - willingness to pay disparity raises questions about accepted economic theory. Plott and Zeiler (2005) have suggested that the disparity is the result of subject misconception about experimental procedures and, in an experiment designed to control for subject misconception, they show that the disparity can be turned on and off. This paper investigates a single feature of their experimental procedure - the prompt for subjects to consider revising their offers. Using the post-prompt and revision offers, we, like Plott and Zeiler, are unable to reject equality...

Scarification with boiling water plus stratification was most effective in improving germination of Iliamna rivularis (Douglas ex Hook.) Greene (Malvaceae) in an experiment that compared 3 treatments. Seeds from 15 sites representing 5 western US states were used in the experiment. Initial response of the seedlots to the treatments was similar, apart from one seedlot. The control treatment (intact seeds) yielded poor germination (1.8%). Mechanical scarification (part of the seedcoat removed) improved germination (average germination 49%), but not as much as the combination of boiling the...

Invasive plants are monitored through canopy cover estimates for a list of species developed by FIA for the northern region of the U.S. that is integrated with a national list. Nearly all of the invasive plants on the NRS-FIA list are exotic species, but a few native species are listed. Highly invasive native species such as rhizomatous fern are absent, making the list limited in scope. Some useful applications include describing all vegetation other than trees, competing vegetation, as well as indices for "invasive-ness," "native-ness," and others. The major advantage of the invasive...

The Forest Inventory and Analysis Program of the Northern Research Station (NRS-FIA) has implemented new Advance Tree Seedling Regeneration (ATSR) protocols that include measurements of seedlings down to 2 inches in height. The addition of ATSR protocols is part of an evaluation of NRS-FIA Phase 3 indicator variables to increase sampling intensity from 1/96,000 acres to 1/24,000 acres per sample location. The sampling scheme for understory vegetation consists of (1) estimating canopy-cover percent for six vegetation growth habits on 24-foot-radius subplots in four height classes and as an...

The biology, recognition, and impact of eriophyid mites (with emphasis on species associated with trees and shrubs) are briefly reviewed. A case study of a leaf-curling eriophyid mite (Aceria sp.) attacking New Mexico olive (Forestiera pubescens Nutt. var. pubescens) is used to illustrate the complexities of developing control strategies for eriophyids in native plant nurseries. The effect of different acaricide treatments at various spray intervals are reported.

Red elm (Ulmus rubra), gray alder (Alnus incana), and buffaloberry (Shepherdia canadensis) are considered important plants for many Native American tribes in the United States. Native Americans use these 3 species for a variety of traditional and medicinal purposes. For example, red elm is still the preferred firewood for the cultural ceremonies of several tribes. Kansas tribal leaders would like to plant more of these species on tribal land, but they have been difficult to germinate due to seed dormancy mechanisms. While red elm is valued as a ceremonial tree, it is susceptible to Dutch...