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Kathleen K. Smith, professor in the Department of Biology at Duke University, took over the directorship of the National Evolutionary Synthesis Center (NESCent) from Clifford Cunningham this past January. NESCent is now hosting conferences, postdoctoral students, and sabbatical faculty, and has made impressive steps toward establishing a cyberinfrastructure. AIBS is providing education and outreach services to NESCent under the center's grant from the National Science Foundation; last March, at NESCent's spacious new accommodations in a converted cotton mill in Durham, North Carolina, BioScience editor Timothy M. Beardsley interviewed Smith about the center's plans.
The Mesopotamian marshes of southern Iraq had been all but destroyed by Saddam Hussein's regime by the year 2000. Earlier assessments suggested that poor water quality, the presence of toxic materials, and high saline soil conditions in the drained marshes would prevent their ecological restoration and doom the reestablishment of the Marsh Arab culture of fishing and agriculture. However, the high volume of good-quality water entering the marshes from the Tigris and Euphrates Rivers, a result of two record years of snowpack melt in Turkey and Iran, allowed 39% of the former marshes to be reflooded by September 2005. Although reflooding does not guarantee restoration success, our recent field surveys have found a remarkable rate of reestablishment of native macroinvertebrates, macrophytes, fish, and birds in reflooded marshes. However, the future availability of water for restoration is in question, which suggests that only a portion of the former marshes may be restored. Also, landscape connectivity between marshes is greatly reduced, causing concern about local species extinctions and lower diversity in isolated wetlands.
Although desertification is a global phenomenon and numerous studies have provided information on dynamics at specific sites, spatial and temporal variations in response to desertification have led to alternative, and often controversial, hypotheses about the key factors that determine these dynamics. We present a new research framework that includes five interacting elements to explain these variable dynamics: (1) historical legacies, (2) environmental driving variables, (3) a soil-geomorphic template of patterns in local properties and their spatial context, (4) multiple horizontal and vertical transport vectors (water, wind, animals), and (5) redistribution of resources within and among spatial units by the transport vectors, in interaction with other drivers. Interactions and feedbacks among these elements within and across spatial scales generate threshold changes in pattern and dynamics that can result in alternative future states, from grasslands to shrublands, and a reorganization of the landscape. We offer a six-step operational approach that is applicable to many complex landscapes, and illustrate its utility for understanding present-day landscape organization, forecasting future dynamics, and making more effective management decisions.
Transgenic crop varieties are a rapidly expanding and controversial technology. Their effects on biological and cultural diversity are a key issue in an often polarized debate. Here we provide answers to questions about one important example, that of transgenic maize in Mexico. In situ maize diversity in Mexico is present in traditional varieties in farmers' fields, and in wild and weedy relatives of maize. It is likely that transgenes are present in farmers' local maize varieties, but it is unknown whether they have introgressed. Socioeconomic changes, including migration, trade liberalization, and reduced support for Mexican farmers, may also affect maize diversity. Diversity may increase, decrease, or remain the same, but whether this is viewed as good or bad will depend on subjective values.
The location, size, and geography of California, combined with extensive knowledge of successful and failed fish invasions, provide an unusual opportunity to test predictors of invasion success. Our analyses show that different characteristics of alien fishes are important at different stages of the invasion process. We found no set of characters that predicted success for all fish invasions, although some characters increase the probability of success. The factors that best predict invasion success are (a) a history of successful establishment outside the species' native range; (b) characters that promote success at multiple stages of the invasion process (e.g., high physiological tolerance); (c) invaded habitat that more or less matches the alien's native habitat; (d) high fish species richness, including other alien fishes; and (e) propagule size exceeding 100 individuals. The difficulty of predicting the invasion success of alien species points to the need to allow only introductions that have proved to be nonharmful and to take quick action to prevent the spread of new invaders.
In recent years, the mission of many botanic gardens and arboreta has expanded from a traditional focus on developing a horticultural collection to one that includes taking a proactive role in plant conservation. To use their limited resources more effectively, many gardens are seeking ways to quantify their contributions to conservation efforts, both as a self-assessment tool to improve their effectiveness and as a way to give an explicit accounting of activities to donors and funding agencies. We suggest many ways gardens can measure the success of their conservation programs, and present results from a survey conducted to assess current conservation activities at botanic gardens.
Determining the characteristic spatial scales at which species respond most strongly to the amount of available habitat is crucial for developing cross-species scaling rules and for predicting species' responses to landscape modification. A Biologist's Toolbox article by Holland and colleagues (“Determining the Spatial Scale of Species' Response to Habitat,” BioScience 54: 227–233) presents a multiscale approach and computer program (Focus) for detecting characteristic scales using a resampling procedure, species–habitat regression models, and nonoverlapping sampling sites. Holland and colleagues refer to these nonoverlapping areas as “spatially independent sites,” when in fact spatial independence includes additional concerns not addressed by the Focus approach. Here I discuss issues of spatial heterogeneity—spatial autocorrelation and spatial dependence—as they relate to measuring the spatial scaling of organism–environment relationships with regression models. I present an empirical example with cactus bugs (Chelinidea vittiger), demonstrating how spatial heterogeneity complicates the task of determining characteristic scales of species–habitat relationships. Finally, I provide some cautions and suggestions for researchers who are considering using Focus to examine scaling patterns with existing data sets.