528 research outputs found
From Observers to Participants: Joining the Scientific Community
In this essay, we have integrated the voices of our mentors and students to explore 45 years of undergraduate research experiences and their role in shaping our scientific community. In considering our collective experiences, we see undergraduate involvement in research as a rich source of community development, one that has both touched our lives and influenced our teaching
Aboveground Biomass Accumulation in a Tropical Wet Forest in Nicaragua Following a Catastrophic Hurricane Disturbance 1
Among their effects on forest structure and carbon dynamics, hurricanes frequently create large-scale canopy gaps that promote secondary growth. To measure the accumulation of aboveground biomass (AGBM) in a hurricane damaged forest, we established permanent plots 4 mo after the landfall of Hurricane Joan on the Atlantic coast of Nicaragua in October 1988. We quantified AGBM accumulation in these plots by correlating diameter measurements to AGBM values using a published allometric regression equation for tropical wet forests. In the first measurement year following the storm, AGBM in hurricane-affected plots was quite variable, ranging from 26 to 153 Mg/ha, with a mean of 78 (±15) Mg/ha. AGBM was substantially lower than in two control plots several kilometers outside the hurricane's path (331 ±15 Mg/ha). Biomass accumulation was slow (5.36 ± 0.74 Mg/ha/yr), relative to previous studies of forest regeneration following another hurricane (Hugo) and agricultural activity. We suggest that large-scale, homogenous canopy damage caused by Hurricane Joan impeded the dispersal and establishment of pioneer trees and led to a secondary forest dominated by late successional species that resprouted and survived the disturbance. With the relatively slow rate of biomass accumulation, any tightening in disturbance interval could reduce the maximum capacity of the living biomass to store carbon.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73646/1/j.1744-7429.2005.00077.x.pd
Shaping a mental health curriculum for Canada\u27s teacher education programs: Rationale and brief overview
It is a well-known and accepted statistic that one in five Canadian children will experience a significant mental health challenge prior to their 18th birthday; this is a conservative estimate given the many who suffer ‘under the radar’ with transient sadness, depression, and anxiety (Flett & Hewitt, 2013). And if we have yet to be sensitized to this critical period of childhood and adolescence, longitudinal studies indicate that 70% of adults who experience an emotional disorder report having their first onset episode prior to the age of 18 (Kessler et al., 2009)
Spatial Dynamics and Ecosystem Functioning
Ecosystem functioning is dependent upon the way species become distributed across space
An equation for the replacement value of agroforestry
This article examines some of the existing analytical tools which quantify both the ecological and economic aspects of intercropping decisions. The characteristics of tree crops are evaluated to determine how a specific tool, the replacement value of intercropping (RVI), could be modified to better interpret agroforestry improvements to bush fallow farming systems. The modified equation captures some of the potential production improvements associated with agroforestry by accounting for the fraction of time that a field is actually in production over the long run. The result is an improved estimate of the average annual difference between a tree/crop polyculture and a monoculture system which employs fallows.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41763/1/10457_2004_Article_BF00705151.pd
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The Community Ecology of Herbivore Regulation in an Agroecosystem: Lessons from Complex Systems
AbstractWhether an ecological community is controlled from above or below remains a popular framework that continues generating interesting research questions and takes on especially important meaning in agroecosystems. We describe the regulation from above of three coffee herbivores, a leaf herbivore (the green coffee scale, Coccus viridis), a seed predator (the coffee berry borer, Hypothenemus hampei), and a plant pathogen (the coffee rust disease, caused by Hemelia vastatrix) by various natural enemies, emphasizing the remarkable complexity involved. We emphasize the intersection of this classical question of ecology with the burgeoning field of complex systems, including references to chaos, critical transitions, hysteresis, basin or boundary collision, and spatial self-organization, all aimed at the applied question of pest control in the coffee agroecosystem
The Agricultural Matrix and a Future Paradigm for Conservation
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73889/1/j.1523-1739.2006.00582.x.pd
Transformation Textures in Zirconia
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65433/1/j.1151-2916.1993.tb03696.x.pd
The Benefits of Mutualism: A Conceptual Framework
There are three general mechanisms by which phenotypic benefits are transferred between unrelated organisms. First, one organism may purloin benefits from another by preying on or parasitizing the other organism. Second, one organism may enjoy benefits that are incidental to or a by-product of the self-serving traits of another organism. Third, an organism may invest in another organism if that investment produces return benefits which outweigh the cost of the investment. Interactions in which both parties gain a net benefit are mutualistic. The three mechanisms by which benefits are transferred between organisms can be combined in pairs to produce six possible kinds of original or ‘basal’ mutualisms that can arise from an amutualistic state. A review of the literature suggests that most or all interspecific mutualism have origins in three of the six possible kinds of basal mutualism. Each of these three basal mutualisms have byproduct benefits flowing in at least one direction. The transfer of by-product benefits and investment are common to both intra- and interspecific mutualisms, so that some interspecific mutualisms have intraspecific analogs. A basal mutualism may evolve to the point where each party invests in the other, sometimes obscuring the nature of the original interaction along the way. Two prominent models for the evolution of mutualism do not include by-product benefits: Roughgarden's model for the evolution of the damsel-fish anemone mutualism and the ‘Tit-for-Tat’ model of reciprocity. Using the conceptual framework presented here, including in particular by-product benefits, I have shown how it is possible to construct more parsimonious alternatives to both models.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72439/1/j.1469-185X.1995.tb01196.x.pd
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