Non-native vascular flora of the Arctic: Taxonomic richness,distribution and pathways

We present a comprehensive list of non-native vascular plants known from the Arctic, explore their geographic distribution, analyze the extent of naturalization and invasion among 23 subregions of the Arctic, and examine pathways of introductions. The presence of 341 non-native taxa in the Arctic was confirmed, of which 188 are naturalized in at least one of the 23 regions. A small number of taxa (11) are considered invasive; these plants are known from just three regions. In several Arctic regions there are no naturalized non-native taxa recorded and the majority of Arctic regions have a low number of naturalized taxa. Analyses of the non-native vascular plant flora identified two main biogeographic clusters within the Arctic: American and Asiatic. Among all pathways, seed contamination and transport by vehicles have contributed the most to non-native plant introduction in the Arctic.     

New York State’s Classifications- Ambient Air Quality Objectives System

The air pollution potential of any area is directly related to its population and economic development. In New York State, this pollution potential ranges from that existing in the sparsely inhabited recreational zones to that prevailing in the densely populated and/or heavily industrialized areas. No one set of air quality standards or objectives can be developed which can reasonably be applied on a statewide basis. A classifications-air quality objectives system has been adopted by the State Air Pollution Control Board for application in New York State. In accordance with this system, specific areas can be classified in one of 16 categories. Air quality objectives, in keeping with each classification, are designed to protect health and to promote the maximum comfort and enjoyment and use of property consistent with the needs of the area concerned. The system was developed by the staff with the assistance of a council of technical advisors. Units of measurement related to the most important effect of specific contaminants are utilized. Methods of sampling and analysis are specified. The details of the classifications-objectives system, the place of the system in the state’s air resource management plan, the manner in which each segment of the state after study will be classified, and how attainment will be evaluated are described.     

Observations and Model Simulations of Carbon Monoxide Emission Factors from a California Highway

ABSTRACT

A series of twelve intensively monitored 1-hr CO dispersion studies were conducted near Davis, CA, in winter 1996. The experimental equipment included twelve CO sampling ports at elevations up to 50 m, three sonic anemometers, a tethersonde station, aircraft measurements of wind and temperature profile aloft, and a variety of conventional meteorological equipment. The study was designed to explore the role of vehicular exhaust buoyancy during worst-case meteorological conditions, such as low winds oriented in near-parallel alignment with the road during a surface-based nocturnal inversion. From the study, field estimates of the CO emission factor (EF) from a California vehicle fleet were computed using two different methods. The analysis suggests that the CT-EMFAC/ EMFAC (EMission FACtor) models currently used to conduct federal conformity modeling significantly overpredict CO emissions for high-speed, free-flowing traffic on California highways.     

Measurement, Collaborative Learning and Research for Sustainable Use of Ecosystem Services: Landscape Concepts and Europe as Laboratory

Policies at multiple levels pronounce the need to encompass both social and ecological systems in governance and management of natural capital in terms of resources and ecosystems. One approach to knowledge production and learning about landscapes as social–ecological systems is to compare multiple case studies consisting of large spaces and places. We first review the landscape concepts’ biophysical, anthropogenic, and intangible dimensions. Second, we exemplify how the different landscape concepts can be used to derive measurable variables for different sustainability indicators. Third, we review gradients in the three dimensions of the term landscape on the European continent, and propose to use them for the stratification of multiple case studies of social–ecological systems. We stress the benefits of the landscape concepts to measure sustainability, and how this can improve collaborative learning about development toward sustainability in social–ecological systems. Finally, analyses of multiple landscapes improve the understanding of context for governance and management.     

On the elasticity of range limits during periods of expansion

Dispersal is known to play a crucial role in the formation of species' ranges. Recent studies demonstrate that dispersiveness increases rapidly during the range expansion of species due to a fitness increase for dispersers at the expanding front. R. D. Holt concluded, however, that emigration should decline after the period of invasion and hence predicted some range contraction following the initial expansion phase. In this study, we evaluate this hypothesis using a spatially explicit individual-based model of populations distributed along environmental gradients. In our experiments we allow the species to spread along a gradient of declining conditions. Results show that range contraction did emerge in a gradient of dispersal mortality, caused by the rapid increase in emigration probability during invasion and selection disfavoring dispersal, once a stable range is formed. However, gradients in growth rate, local extinction rate, and patch capacity did not lead to a noticeable contraction of the range. We conclude, that the phenomenon of range contraction may emerge, but only under conditions that select for a reduction in dispersal at the range edge in comparison to the core region once the expansion period is over.