Where Have All the Young Trees Gone? A Big Picture Look at the Lack of Seedlings and Saplings in Urban Forests

We take a big picture look at the lack of seedlings, saplings and young trees in urban forests using our research in Forest Park in Portland, Oregon. Broshot, who measured vegetation at 25 sites in Forest Park, recorded significantly fewer live seedlings, saplings and young trees and significantly more dead seedlings, saplings and young trees in 2003 than in 1993. The percent mortality of western red cedar seedlings that were planted at 9 sites in Forest Park in 2005 ranged from less than 5% to over 70%. Investigations into the cause of seedling death has discounted predation by deer, elk or invertebrates, leaf disease, soil moisture, site aspect, and light as factors. The site with the highest mortality is located directly above the St John’s Bridge, suggesting air pollution. More recent work with lichens has provided evidence that nitrogen deposition related to air pollution may be the cause. We outline our past work and report preliminary results from our 2012 lichen survey analysis to support our hypothesis that pollution is a cause of the lack of young trees

A Comparison of Urban Soil to Rural Soils

Previous studies have shown significantly more seedlings and saplings at control sites above Estacada, Oregon than in Forest Park. In an attempt to determine possible reasons for the lack of young trees in the urban forest, we measured the depth of the O horizon, as well as soil Carbon, Nitrogen, and CO2 (as a measure of respiration rate) in soil at multiple sites. We found significantly deeper O2 horizons at the control sites relative to the sites in any section of Forest Park. We also found significantly higher levels of C and higher C/N ratio at the control sites. We did not find significant differences among the level of soil respiration but did see a tendency for higher levels at the control sites

Membrane protein variation in Dictyostelium mucoroides during development along alternative pathways.

Introduction: Dictyostelium is a genus of cellular slime mold which is important in developmental research. The first cellular slime mold to be discovered was Dictyostelium mucoroides. It was discovered by Brefeld in 1869. However, the cellular slime mold most widely used in developmental research today is Dictyostelium discoideum, discovered by Raper in 1935

Knowledge, Awareness, Perceptions, and Use of Emergency Contraceptives among Survivors of Intimate Partner Violence

The study examines emergency contraception (EC) knowledge, awareness, perceptions, and prior use and identifies predictors of EC use among a sample of survivors of intimate partner violence (IPV). The majority (66.2%) of 154 survivors at risk of pregnancy reported EC awareness, only 15.3% reported prior EC use. Logistic regression identified perceived abusive intimate partner approval (OR = 2.25; 95% CI = 1.15–4.41) and lack of moral/religious objections (OR = 12.83; 95% CI = 5.48–30.03) as the strongest predictors of EC use. Health care provider interventions acknowledging barriers to EC use, such as partner approval, and education that improves awareness of and knowledge about EC, may have the impact of empowering survivors in their reproductive choices, reducing unwanted pregnancies

EUV spectroscopy of 3 RSCVn binaries

The extreme ultraviolet (EUV) spectroscopy of several binary stars containing cool components is used to define the high temperature plasma structure of these stars and their stellar atmospheres. Different line emission spectra are reported, along with a spectrum analysis of Capella, a nearby bright multiple star system, using data from the EUVE satellite

High temperature structure in cool binary stars

Strong high temperature emission lines in the EUVE spectra of binary stars containing cool components (Alpha Aur (Capella), 44 iota Boo, Lambda And, and VY Ari) provide the basis to define reliably the differential emission measure of hot plasma. The emission measure distributions for the short-period (P less than or equal to 13 d) binary systems show a high temperature enhancement over a relatively narrow temperature region similar to that originally found in Capella (Dupree et al. 1993). The emission measure distributions of rapidly rotating single stars 31 Com and AB Dor also contain a local enhancement of the emission measure although at different temperatures and width from Capella, suggesting that the enhancement in these objects may be characteristic of rapid rotation of a stellar corona. This feature might be identified with a (polar) active region, although its density and absolute size are unknown; in the binaries Capella and VY Ari, the feature is narrow and it may arise from an interaction region between the components

Prospectus, September 27, 1990

https://spark.parkland.edu/prospectus_1990/1022/thumbnail.jp