National workshop convened to review the latest techniques available to quantify relationships between habitat features and fish production. The workshop focused on salmonids because of their importance on both the Atlantic and Pacific coasts, but effects on other non-salmonid populations were included since data is scarce in some areas. Coverage included methodologies for the quantification of the effects of habitat alteration on yield, empirical examples of the effects of physical and chemical habitat changes on stocks, and the permissable degree of extrapolation in assigning effects of habitat alteration to a stock.
Tidal salt marshes are viewed as critical habitats for the production of fish and shellfish. As a result, considerable legislation has been promulgated to conserve and protect these habitats, and much of it is in effect today. The relatively young science of ecological engineering has also emerged, and there are now attempts to reverse centuries-old losses by encouraging sound wetland restoration practices. Today, tens of thousands of hectares of degraded or isolated coastal wetlands are being restored worldwide. Whether restored wetlands reach functional equivalency to `natural' systems is a subject of heated debate. Equally debatable is the paradigm that depicts tidal salt marshes as the `great engine' that drives much of the secondary production in coastal waters. This view was questioned in the early 1980s by investigators who noted that total carbon export, on the order of 100 to 200 g m-2 y-1 was of much lower magnitude than originally thought. These authors also recognized that some marshes were either net importers of carbon, or showed no net exchange. Thus, the notion of `outwelling' has become but a single element in an evolving view of marsh function and the link between primary and secondary production. The `revisionist' movement was launched in 1979 when stable isotopic ratios of macrophytes and animal tissues were found to be `mismatched'. Some eighteen years later, the view of marsh function is still undergoing additional modification, and we are slowly unraveling the complexities of biogeochemical cycles, nutrient exchange, and the links between primary producers and the marsh/estuary fauna. Yet, since Teal's seminal paper nearly forty years ago, we are not much closer to understanding how marshes work. If anything, we have learned that the story is far more complicated than originally thought. Despite more than four decades of intense research, we do not yet know how salt marshes function as essential habitat, nor do we know the relative contributions to secondary production, both in situ or in the open waters of the estuary. The theme of this Symposium was to review the status of salt marsh research and revisit the existing paradigm(s) for salt marsh function. Challenge questions were designed to meet the controversy head on: Do marshes support the production of marine transient species? If so, how? Are any of these species marsh obligates? How much of the production takes place in situ versus in open waters of the estuary/coastal zone? Sessions were devoted to reviews of landmark studies, or current findings that advance our knowledge of salt marsh function. A day was also devoted to ecological engineering and wetland restoration papers addressing state-of-the-art methodology and specific case histories. Several challenge papers arguing for and against our ability to restore functional salt marshes led off each session. This volume is intended to serve as a synthesis of our current understanding of the ecological role of salt marshes, and will, it is hoped, pave the way for a new generation of research.
Various papers are presented on the topics of invertebrate management ingeneral; the sampling of adults, juveniles and larval forms;population dynamics and models; exploration and multispecies interactions;and management strategies. An overall workshop summary is included.
Forests cover approximately 26% of the world's land surface area and represent a distinct biotic community. They interact with water and soil in a variety of ways, providing canopy surfaces which trap precipitation and allow evaporation back into the atmosphere, thus regulating how much water reaches the forest floor as through fall, as well as pull water from the soil for transpiration. The discipline "forest hydrology" has been developed throughout the 20th century. During that time human intervention in natural landscapes has increased, and land use and management practices have intensified. The book will be useful for graduate students, professionals, land managers, practitioners, and researchers with a good understanding of the basic principles of hydrology and hydrologic processes.
The Forest Practices Code guidebooks help forest resource managers plan, prescribe and implement sound forest practices that comply with the Forest Practices Code. This guidebook is designed to be a "fine filter" approach to addressing habitat requirements of critical wildlife, in addition to the "coarse filter" approach provided by the Biodiversity Guidebook and the Riparian Management Area Guidebook.
