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Some plant species are particularly well adapted to environments disturbed by humans. Often such species are invasive and problematic, and thus are classified as weeds. Despite our best efforts to manage weeds, they continue to interfere with crop production. There is clearly much to learn about weeds, information that could aid in weed management and improve competitiveness in nonweedy species. The tools of molecular biology have been enlisted in ongoing efforts to manage weeds, most notably in the development and commercialization of crop plants tailored to resist certain herbicides. Molecular biology also has been used to gain a better understanding of how weeds compete and interact with neighboring plants, survive harsh environmental conditions, and evolve resistance to the herbicides used to control them. The next generation of molecular biology tools, such as genomic resources, may yield novel weed management strategies and shed new light on what makes plants weedy.
For a resident of the state of Nebraska, the Cedar Point Biological Station (CPBS), located in scenic limestone bluffs below Kingsley Dam, an earth-filled artificial mountain that impounds a lake 35 kilometers long and 5 kilometers wide, is a bargain in American higher education. In three weeks a student can earn four credits of upper-division coursework, get original research experience, and, most importantly—especially in an educational milieu increasingly characterized by electronic content and electronic course management—get his or her hands on some live wild plants and animals in an appropriate ecological context. This encounter with nature is typically the first for our high-performer premed students on academic scholarships, who regularly attend CPBS after their junior year. The life-long impact of such experience includes lost naïveté with respect to living systems, appreciation of the relationship between environment and health, and, for some, a career choice leading to professional science.
Research on ecosystem services has grown rapidly over the last decade. Two conceptual frameworks have been published to guide ecological assessments of organisms that deliver services—the concepts of service-providing units (SPUs) and ecosystem service providers (ESPs). Here, we unite these frameworks and present an SPU-ESP continuum that offers a coherent conceptual approach for synthesizing the latest developments in ecosystem service research, and can direct future studies at all levels of organization. In particular, we show how the service-provider concept can be applied at the population, functional group, and community levels. We strongly emphasize the need to identify and quantify the organisms and their characteristics (e.g., functional traits) that provide services, and to assess service provision relative to the demands of human beneficiaries. We use key examples from the literature to illustrate the new approach and to highlight gaps in knowledge, particularly in relation to the impact of species interactions and ecosystem dynamics on service provision.
Arid and semiarid regions cover more than 40% of Earth's land surface. Desertification, or broadscale land degradation in drylands, is a major environmental hazard facing inhabitants of the world's deserts as well as an important component of global change. There is no unifying framework that simply and effectively explains different forms of desertification. In this article, we argue for the unifying concept that diverse forms of desertification, and its remediation, are driven by changes in the length of connected pathways for the movement of fire, water, and soil resources. Biophysical feedbacks increase the length of connected pathways, explaining the persistence of desertified landscapes around the globe. Management of connectivity in the context of environmental and socioeconomic change is essential to understanding, and potentially reversing, the harmful effects of desertification.
Nonindigenous species, which are associated with the decline of many threatened and endangered species, are a major threat to global diversity. This risk extends to salmonids, the most widespread threatened and endangered species in the Pacific Northwest. Pacific salmonids traverse large geographic areas that include freshwater, estuarine, and ocean habitats in which they encounter numerous nonnative species. For this article, we examined the extent to which introduced species are a risk to threatened and endangered salmon. We identified all documented nonindigenous species in the Pacific Northwest, including fish, invertebrates, birds, plants, and amphibians. Where data exist, we quantified the impact of nonindigenous species on threatened and endangered salmonids. The results indicate that the effect of nonindigenous species on salmon could equal or exceed that of four commonly addressed causes of adverse impacts—habitat alteration, harvest, hatcheries, and the hydrosystem; we suggest that managing nonindigenous species may be imperative for salmon recovery.
The lesser prairie-chicken (Tympanuchus pallidicinctus) is an umbrella species for the short- and mixed-grass prairie ecosystem of the south-central United States. This species has suffered large population declines over the last century that mirror the loss of prairie. Populations have become increasingly fragmented, and habitat connections between populations are being severed. A possible new threat to lesser prairie-chickens is the rapid development of wind-energy facilities throughout their habitat. In addition to contributing to the loss of prairie, these facilities could serve as barriers to movement if birds avoid wind turbines and their associated power transmission lines. We summarize evidence for avoidance behavior in birds, propose connectivity areas between distributional cores, propose strategies for conservation of lesser prairie-chickens, and encourage lawmakers to adopt state and federal regulations on wind-farm placement. Without a concerted effort, lesser prairie-chickens and similar species are likely to disappear, as will the southern prairie on which they depend.