Treesearch

Nutrient pollution of freshwater ecosystems results in predictable increases in carbon (C) sequestration by algae. Tests of nutrient enrichment on the fates of terrestrial organic C, which supports riverine food webs and is a source of CO2, are lacking. Using whole-stream nitrogen (N) and phosphorus (P) additions spanning the equivalent of 27 years, we found that average terrestrial organic C residence time was reduced by ~50% as compared to reference conditions as a result of nutrient pollution. Annual inputs of terrestrial organic C were rapidly depleted via release of detrital food webs...

We know surprisingly little about whole-tree nonstructural carbon (NSC; primarily sugars and starch) budgets. Even less well understood is the mixing between recent photosynthetic assimilates (new NSC) and previously stored reserves. And, NSC turnover times are poorly constrained. We characterized the distribution of NSC in the stemwood, branches, and roots of two temperate trees, and we used the continuous label offered by the radiocarbon (carbon-14, 14C) bomb spike to estimate the mean age of NSC in different tissues.

Proper irrigation can reduce water use, water waste, and incidence of disease. Knowing when to irrigate plants in container nurseries can be determined by weighing containers. This simple method is quantifiable, which is a benefit when more than one worker is responsible for irrigation. Irrigation is necessary when the container weighs some target as a proportion of its weight at field capacity. Care should be taken when comparing target container weights because they can be calculated different ways. In the nursery, one easy method for obtaining weights is using a small, handheld portable...

Dramatic fluctuations in food resources are a key feature of many habitats, and many species have evolved a movement strategy to exploit food resources that are unpredictable in space and time. The availability of food resources may be a particularly strong determinant of habitat quality for irruptive bird species. We studied the apparent foraging success of Black-backed Woodpeckers (Picoides arcticus), an irruptive species that responds opportunistically to pulsed food resources in burned forests and mountain pine beetle (MPB) infestations. Prior investigations revealed that the highest...

Urban forests provide many societal and ecological services to cities and their inhabitants. Many species of trees are under stress due to anthropogenic and natural climate changes. Projected climatic shifts will change temperature, precipitation, and the incidences of pest and disease outbreaks. The tolerance of urban trees to these stressors varies considerably among species and the perpetuation of urban forests depends on tree species resilience to climate induced stress within particular climate zones. The purpose of this study is to provide new information on what tree species to...

The ability to estimate and monitor standing dead trees (snags) has been difficult due to their irregular and sparse distribution, often requiring intensive sampling methods to obtain statistically significant estimates. This study presents a new method for estimating and monitoring snags using neighborhood attribute filtered airborne discrete-return lidar data. The method first develops and then applies an automated filtering algorithm that utilizes three dimensional neighborhood lidar point-based intensity and density statistics to remove lidar points associated with live trees and...

This resource update provides an overview of forest resources in Wisconsin based on an inventory conducted by the U.S. Forest Service, Forest Inventory and Analysis (FIA) program at the Northern Research Station in cooperation with the Wisconsin Department of Natural Resources (WDNR). Data estimates are based on field data collected using the FIA annualized sample design and are updated yearly. The estimates presented in this update are for the measurement year 2014. For annual inventory years in Wisconsin 2001-2013, the cycle length was equal to 5 years; beginning in 2014, the cycle...

This resource update provides an overview of forest resources in Minnesota based on an inventory conducted by the U.S. Forest Service, Forest Inventory and Analysis (FIA) program at the Northern Research Station in cooperation with the Minnesota Department of Natural Resources. Estimates are based on field data collected during measurement years 2009-2014 with comparisons made to field data collected in 2005-2009. The 2009-2014 sample data consist of 6,226 field measured plots on forest land, with from 14 to 20 percent collected per year. Data used in this publication were accessed from...

The influence of substrate lithology on the distribution of many vascular and nonvascular plants has long been recognized, especially in alpine, subalpine, and other rocky habitats. In particular, plants have been classified as dependent on high-calcium substrates (i.e., calcicoles) based on common restriction to habitats developed in calcareous rocks, such as limestone and marble. In a classic 1907 paper on the influence of substrate on plants, M. L. Fernald singled out a particular meadow on Mont de la Table in the Chic-Choc Mountains of Quebec for its unusual co-occurrence of strict...

We measured dynamic stress responses using ambulatory heart rate monitoring as participants in Philadelphia, Pennsylvania walked past vacant lots before and after a greening remediation treatment of randomly selected lots. Being in view of a greened vacant lot decreased heart rate significantly more than did being in view of a nongreened vacant lot or not in view of any vacant lot. Remediating neighborhood blight may reduce stress and improve health.