Suchergebnisse

A major public university is located in or very near over half of
American state capitals, and political science departments at these
universities advertise the special advantages that such a location
brings to their students. For example, the political science
department of the University of Nebraska-Lincoln advertises its
internship programs: "As Lincoln is the seat of state government,
students have an opportunity to observe government in action.
Political Science has a vibrant internship program where students
may intern with the state legislature, the governor's office, and
other agencies of state government. Internships are also available
with local interest groups, non-profit agencies, corporations, and
political parties" (University of Nebraska-Lincoln 2005). Such opportunities for students are
meaningful, however, only if they have some significant effect on
student learning or engagement. It is reasonable that colleges and
universities would emphasize the advantages that their location in a
state capital might offer; colleges use both their campus and their
local community to appeal to students (Choy and Ottinger 1998). Yet there is scant research to
confirm any of the effects that colleges advertise. An earlier version of this article was presented
at the 2005 meeting of the American Political Science
Association. The authors thank Lindsey Lupo, Charles Turner, and
the anonymous reviewers for their comments and
suggestions.

Human land use threatens global biodiversity and compromises multiple ecosystem functions critical to food production. Whether crop yield-related ecosystem services can be maintained by a few dominant species or rely on high richness remains unclear. Using a global database from 89 studies (with 1475 locations), we partition the relative importance of species richness, abundance, and dominance for pollination; biological pest control; and final yields in the context of ongoing land-use change. Pollinator and enemy richness directly supported ecosystem services in addition to and independent of abundance and dominance. Up to 50% of the negative effects of landscape simplification on ecosystem services was due to richness losses of service-providing organisms, with negative consequences for crop yields. Maintaining the biodiversity of ecosystem service providers is therefore vital to sustain the flow of key agroecosystem benefits to society. [Abstract copyright: Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).]

Human land use threatens global biodiversity and compromises multiple ecosystem functions critical to food production. Whether crop yield-related ecosystem services can be maintained by a few dominant species or rely on high richness remains unclear. Using a global database from 89 studies (with 1475 locations), we partition the relative importance of species richness, abundance, and dominance for pollination; biological pest control; and final yields in the context of ongoing land-use change. Pollinator and enemy richness directly supported ecosystem services in addition to and independent of abundance and dominance. Up to 50% of the negative effects of landscape simplification on ecosystem services was due to richness losses of service-providing organisms, with negative consequences for crop yields. Maintaining the biodiversity of ecosystem service providers is therefore vital to sustain the flow of key agroecosystem benefits to society. Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).