Monitoring and modelling the effects of ecosystem engineers on ecosystem functioning

Biodiversity is crucial for supporting ecosystem functioning, yet some species play a disproportionate role in maintaining complex ecological processes. Ecosystem engineers are species that directly influence ecosystems by modifying biophysical environments, creating novel habitats, altering biogeochemical cycles, increasing biodiversity and/or modulating ecological processes. Although these species may substantially influence ecosystem functioning, their role is often overlooked and difficult to quantify. Understanding the status, dynamics and trends of ecosystem engineers is essential for mitigating biodiversity loss and maintaining healthy ecosystems. This review reveals the common but underappreciated roles that ecosystem engineers play in ecosystem functioning across many different taxa, biomes and ecological processes. We first synthesise how knowledge of ecosystem engineering improves our understanding of species interactions and the ecological processes underlying both ecosystem functioning and BEF relationships. We provide a conceptual model for addressing the effects of ecosystem engineers in BEF research and ecological dynamics. We provide a ‘how to’ analytical framework for monitoring and quantifying changes in ecosystem engineers and their effects on ecosystem functioning. This framework includes (i) what variables to measure, how and at which scale; (ii) experiments involving species exclusion or removal, introduction and comparative designs when experimental manipulation is not feasible and (iii) statistical, data-driven and theory-driven models. We discuss how to leverage ecosystem engineering in the context of current global change and ecosystem restoration efforts. Including ecosystem engineers in conservation and restoration programs, when implemented in the appropriate context and supported by an understanding of ecological mechanisms and processes, may be crucial for sustaining biological diversity and functional ecosystems

A DYNAMIC ANALYSIS OF EDUCATIONAL ATTAINMENT, OCCUPATIONAL CHOICES, AND JOB SEARCH

This article examines career choices using a dynamic structural model that nests a job search model within a human capital model of occupational and educational choices. Wage growth occurs in the model because workers move between firms and occupations as they search for suitable job matches and because workers endogenously accumulate firm and occupation specific human capital. Simulations performed using the estimated model reveal that both self-selection in occupational choices and mobility between firms account for a much larger share of total earnings and utility than the combined effects of firm and occupation specific human capital. Copyright (2010) by the Economics Department of the University of Pennsylvania and the Osaka University Institute of Social and Economic Research Association.