Abundance changes of neophytes and native species indicate a thermophilisation and eutrophisation of the Swiss flora during the 20th century

2005 ◽

Keyword(s):

New York ◽

20Th Century ◽

Native Species ◽

Fish Assemblages ◽

Fish Habitat ◽

Large River ◽

Anadromous Fish ◽

Susquehanna River ◽

Assessment Specialists ◽

Industrial Operations

<em>Abstract.</em>—The Susquehanna River drains portions of New York, Pennsylvania, and Maryland, and is the 18th largest river (by discharge) in the United States. Although relatively undeveloped (i.e., 63% of the basin is forested, whereas 9% is urban), the river and its fish assemblage have experienced stresses associated with coal mining, logging, electric power generation, population growth, and agricultural and industrial operations. Surveys of Susquehanna River fishes have a rich history, with the qualitative surveys of 19th century naturalists giving way to the quantitative studies of 20th century environmental impact assessment specialists. Ichthyofaunal surveys of the Susquehanna drainage were compiled and summarized herein to examine species composition, losses, and additions. Collection records indicate that the Susquehanna River drainage supports a diverse and relatively stable assemblage of 60 native species (or 51% of all species), 33 (28%) alien species, 22 (19%) euryhaline or diadromous fishes, and 2 (2%) extirpated or extinct species. Stocking efforts, bait-bucket releases, range extensions, and new species descriptions accounted for most contemporary species additions. Overall reduction in species richness has been limited to one cyprinid that has not been collected since 1862, and one darter species that has not been collected since 1987. Construction of four large hydroelectric dams on the lower Susquehanna (in the early 20th century) eliminated 98% of historic anadromous fish habitat, leading to notable reductions in commercial/ recreational clupeid stocks. Recent increases in the occurrence and abundance of anadromous fish in the Susquehanna River are a credit to an extensive restoration program that began with fish trap and transfer operations in 1972, included fish culture programs, and led to the installation of fish passage technologies at each of the four dams.

Download Full-text

THE IMPORTANCE OF WOODY PLANT INTRODUCTION FOR FOREST TREES IMPROVEMENT

AGROFOR ◽

10.7251/agreng1702056i ◽

2018 ◽

Vol 2 (2) ◽

Author(s):

Vasilije ISAJEV ◽

Milena STANKOVIC ◽

Sasa ORLOVIC ◽

Stefan BOJIC ◽

Srdjan STOJNIC

Keyword(s):

20Th Century ◽

Native Species ◽

Large Scale ◽

Woody Plant ◽

Woody Species ◽

Well Being ◽

Plant Introduction ◽

Potential Productivity ◽

History Of ◽

The Impact

The history of woody plant introduction is closely linked with that of transportationand the European exploration of the planet (16th–19th centuries). Each colonialpower established major botanical gardens and experimental stations in variousparts of the world. By the 20th century, the purpose of introductions shifted fromfood plants to timber and other species yielding non-agricultural products. Finally,during the latter part of the 20th century the importance of ornamental speciesincreased dramatically, especially to the more developed and wealthier regions.Over the past two centuries many species have started to spread in their introducedranges. Until relatively recently the majority of introduced woody species havebeen highly beneficial, if not essential, to humanity’s development, but now everincreasingnumbers of species are becoming detrimental to the maintenance of theearth’s biodiversity and to the well-being of human societies. Throughout the 19thand specially in 20th century the large-scale planting of trees for timber productionhas been one of the main reasons for the introductions of a large number of species,especially conifers e.g. Pinus, Picea. Pseudotsuga and Poplars and Willowsspecies. By using methods of mass and individual selection and by establishing ofprovenances tests, as well as by half and full sib lines of selected exotics test trees,genetical potential productivity and adaptability of introduced species have beentested in numerous experimental plots in areas where introduced have been done.This paper attempts to unravel the relationships between humans and woody plantsby looking at the changes in the introduction of species, the way they are perceivedby different human groups and the impact these non native species have on foresttrees improvement and other human activities.

Download Full-text

Conceptual Developments of 20th Century Field Theories

10.1017/cbo9780511563997 ◽

1997 ◽

Cited By ~ 54

Author(s):

Tian Yu Cao

Keyword(s):

20Th Century ◽

Field Theories

Download Full-text

Radicalism and Education Reform in 20th-Century China

10.1017/cbo9780511584725 ◽

1996 ◽

Cited By ~ 94

Author(s):

Suzanne Pepper

Keyword(s):

Education Reform ◽

20Th Century

Download Full-text

Econometrics and Economic Theory in the 20th Century: The Ragnar Frisch Centennial Symposium

10.1017/ccol0521633230 ◽

1998 ◽

Cited By ~ 4

Keyword(s):

Economic Theory ◽

20Th Century

Download Full-text

Econometrics and Economic Theory in the 20th Century

10.1017/ccol521633230 ◽

1999 ◽

Cited By ~ 13

Keyword(s):

Economic Theory ◽

20Th Century

Download Full-text

Development of Reading Remediation for Dyslexic Individuals

Zeitschrift für Psychologie ◽

10.1027/2151-2604/a000259 ◽

2016 ◽

Vol 224 (4) ◽

pp. 240-246 ◽

Cited By ~ 4

Author(s):

Mélanie Bédard ◽

Line Laplante ◽

Julien Mercier

Keyword(s):

20Th Century ◽

Scientific Literature ◽

Behavioral Data ◽

Educational Neuroscience ◽

Reading Remediation ◽

Functional Brain ◽

Neurophysiological Data ◽

Brain Correlates ◽

Research Questions ◽

The Brain

Abstract. Dyslexia is a phenomenon for which the brain correlates have been studied since the beginning of the 20th century. Simultaneously, the field of education has also been studying dyslexia and its remediation, mainly through behavioral data. The last two decades have seen a growing interest in integrating neuroscience and education. This article provides a quick overview of pertinent scientific literature involving neurophysiological data on functional brain differences in dyslexia and discusses their very limited influence on the development of reading remediation for dyslexic individuals. Nevertheless, it appears that if certain conditions are met – related to the key elements of educational neuroscience and to the nature of the research questions – conceivable benefits can be expected from the integration of neurophysiological data with educational research. When neurophysiological data can be employed to overcome the limits of using behavioral data alone, researchers can both unravel phenomenon otherwise impossible to document and raise new questions.

Download Full-text