An emerging theoretical framework demystifies ecological tipping points and elucidates some long-standing environmental problems, providing a perspective that is both sobering and hopeful.

Traditional plant hardiness zone maps identify areas that are relatively homogeneous with respect to climatic conditions that affect plant survival. Plants are typically categorized according to the most northerly, and sometimes the most southerly, zone in which they can successfully grow. This approach suffers from a number of limitations, including the coarse spatial nature of the zones and the relatively unsystematic assignment of plants to zones. Here we propose using climate envelopes to map the potential ranges of plant species in North America in wild and cultivated settings. We have initiated a major data-gathering effort that currently includes over 1.8 million georeferenced observations for more than 4100 plant species. We demonstrate the approach using sugar maple (Acer saccharum) and show the ease with which predicted climate-change impacts can be incorporated into the models.

Currently predicted change in climate could strongly affect plant distributions during the next century. Here we determine the present-day climatic niches for 130 North American tree species. We then locate the climatic conditions of these niches on maps of predicted future climate, indicating where each species could potentially occur by the end of the century. A major unknown in this work is the extent to which populations of trees will actually track climate shifts through migration. We therefore present two extreme scenarios in which species either move entirely into future climatic niches or do not move out of their current niches. In the full-dispersal scenario, future potential ranges show decreases and increases in size, with an average decrease of 12% and a northward shift of 700 kilometers (km). In the no-dispersal scenario, potential ranges decrease in size by 58% and shift northward by 330 km. Major redistribution pressures appear to be in order under both dispersal scenarios.

Although animal-derived remedies constitute an integral part of folk medicine in many parts of the world, particularly for people with limited or no access to mainstream medical services, their role in health care has generally been overlooked in discussions about public health, conservation and management of faunistic resources, and ecosystem protection. In this article, we report on the use of 283 medicinal animal species in Brazil, 96% of which are wild caught and 27% of which are on one or more lists of endangered species. Further population declines may limit users' access to these bioresources and diminish the knowledge base upon which traditional medicine is built.

The Callery pear (Pyrus calleryana Dcne. [Rosales: Rosaceae]), an ornamental tree from China, has begun appearing in disturbed areas throughout the United States. To understand the relatively recent spread of this species into natural areas, we review its horticultural history, the traits promoting its invasiveness, and its current invasive status. Cultivated varieties (cultivars) of this species sold in the United States originate from different areas in China and represent genotypes that have been planted in high densities in residential and commercial areas in the introduced range. The species cannot self-pollinate because of a self-incompatibility system, but recent fruit set is due to crossing between different cultivars or between the scion and rootstock of cultivated individuals. Consequently, individual cultivars themselves are not invasive, but the combination of cultivars within an area creates a situation in which invasive plants can be produced. Because of the established nature of this species in urban areas, the spread of wild P. calleryana will most likely continue, especially as new cultivars continue to be introduced into the mixture of cultivars already present.

Interdisciplinary research programs are needed to address complex medical and scientific issues. Such programs are difficult to launch, however, in part because scientists who might work in interdisciplinary teams often lack shared experiences and shared concepts. In this article, we report on a study that examined the extent of shared experience and understanding among participants in an emerging interdisciplinary medical research field; the study also documented participants' thoughts about changes they considered likely to take place if the interdisciplinary effort succeeded. Subjects generally agreed about the roles of their respective fields in the new effort, but their understanding of the objectives, methods, and language of other fields varied. Data show that subjects envision the new interdisciplinary field primarily as a centralizing and coordinating force. Concept mapping was a particularly successful research method applied to this group. This study yielded useful insights about commonalities among participants and identified areas for future development.

Studies of biodiversity rely on taxonomically recognized variation to establish regions of special evolutionary and conservation interest. The number of species known from a region relates well to the number of taxonomists working on that region. It is important that we evaluate the philosophy of taxonomists, who have a large impact on our tally of species. Yet, philosophy of what constitutes a species, race, or variety differs among taxonomists and between periods of an individual taxonomist's career. Hence, our modern crisis in taxonomic expertise translates directly into a crisis in revisionary systematics. We must invest more in training traditional scholars.