Sectional notes     

H. W. Poulsen  H. G. Zuckerman  C. H. Metzger  W. B. Ward  W. C. Edmundson  E. R. Bennet  R. A. Jehle  A. B. Beaumont  John S. Gardner  E. L. Newdick  Frank W. Hussey  E. J. Wheeler  H. C. Moore  Marx Koehnke  A. G. Tolaas  E. E. Isaac  H. O. Werner  O. Butler  William H. Martin  K. H. Fernow  E. R. Jackman  E. B. Tussing  E. V. Hardenburg  J. B. R. Dickey  K. H. Klages  G. S. Ralston  H. L. Bailey  John Tucker 《American Journal of Potato Research》1934,11(8):207-226

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How climate change might affect tree regeneration following fire at northern latitudes: a review     

Boucher  Dominique  Gauthier  Sylvie  Thiffault  Nelson  Marchand  William  Girardin  Martin  Urli  Morgane 《New Forests》2020,51(4):543-571

New Forests - Climate change is projected to increase fire severity and frequency in the boreal forest, but it could also directly affect post-fire recruitment processes by impacting seed...  相似文献   

Carl Ortwin sauer on destructive exploitation     

William W. Speth 《Biological conservation》1977,11(2):145-160

A persistent theme in the work of Carl O. Sauer (1889–1975) is destructive exploitation, the process of economic devastation and its aftermath associated with occidental commercial culture. Coloured by anthropological premise, his conception entailed economic process as cause, e.g. monoculture, and environmental pathology as consequence, e.g. soil wastage. Man is both selective appraiser and selective modifier of his habitat, and many of his surface changes are irreversible. Primitive economies are part of the general symbiosis and infrequently destroy things that are useful to them. Man's terrible destructiveness is an attribute of profit economies, colonial and contemporary. Among other losses, the record of impoverishment includes devastation of native peoples and cultures, extermination of biotic species and varieties, and soil erosion. Sauer infused record of deformation with moral critique. He inveighed against ways that are improvident and called for an ethic and aesthetic under which man may attain wise stewardship of the earth.  相似文献   

Calcium oxalate accumulation and soil weathering in mats of the hypogeous fungus Hysterangium crassum     

Kermit Cromack  Phillip Sollins  William C. Graustein  Karen Speidel  Allen W. Todd  Gody Spycher  Ching Y. Li  Robert L. Todd 《Soil biology & biochemistry》1979,11(5):463-468

Fungal mats of Hysterangium crassum (Tul. and Tul.) Fischer occupied a mean of 9.6% of the upper 10 cm of soil developed under a 40–65 yr old stand of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) in Oregon. This hypogeous basidiomycete exudes large amounts of oxalic acid, some of which precipitates with Ca in microscopic crystals of calcium oxalate, resulting in a mean CaC₂O₄ content of 82g m^?2 for the entire soil. Soil oxalate concentration was significantly greater within fungal mats (P < 0.01) and soil pH was significantly lower (P < 0.01) than in soil adjacent to mats. The quantity of Ca present as CaC₂O₄ is 0.5 the amount of exchangeable Ca in the soil and exceeds the mass of Ca lost annually in runoff. Scanning electron micrographs show intense chemical weathering, attributable to oxalate attack, in the immediate vicinity of hyphae. X-ray diffraction patterns of clay indicate bulk weathering is more intense within the fungal mats than in adjacent uncolonized soil.  相似文献   

Program Of The Twenty-Seventh Annual Meeting of The Potato Association of America December 29-31, 1940     

C. H. Metzger  William H. Martin 《American Journal of Potato Research》1940,17(12):340-342

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Phenotypic differences may limit the potential for habitat restoration involving species translocation: a case study of shape ecophenotypes in different populations of Modiolus modiolus (Mollusca: Bivalvia)          下载免费PDF全文

Jose M. Fariñas‐Franco  William G. Sanderson  Dai Roberts 《水产资源保护:海洋与淡水生态系统》2016,26(1):76-94

Fish assemblages in the Southern California Current: relationships with climate, 1951–2008     

J. Anthony Koslow  Ralf Goericke  William Watson 《Fisheries Oceanography》2013,22(3):207-219

We examined the dominant patterns of variability in the fish fauna of the southern California Current based on a principal component (PC) analysis of the California Cooperative Oceanic Fisheries Investigations ichthyoplankton data set, 1951–2008. Eighty‐six taxa were analyzed, including all ecologically dominant fish species, both exploited and unexploited. The first three PCs accounted for 20.5, 12.4 and 6.8% of the variance of the data, respectively (total: 39.7%). Each was dominated by taxa from particular adult or larval habitats. PC 1 predominantly represented the coherent response of 24 mesopelagic taxa from 10 families and was most highly correlated with long‐term trends in midwater oxygen levels. PC 2 was dominated by six of the seven most abundant ichthyoplankton taxa in the region, predominantly California Current endemics including key pelagic species (northern anchovy, Pacific sardine and Pacific hake), rockfishes (genus Sebastes) and two midwater taxa. It was correlated primarily with sea surface temperature and exhibited a significant declining trend. PC 3 was dominated by coastal and reef‐associated fishes with predominantly southerly affinities. It was positively correlated with sea surface temperature and sea level height, a proxy for diminished flow of the California Current. The taxa dominating PCs 2 and 3 mostly spatially co‐occur as ichthyoplankton. These results suggest that fish assemblages in the California Current are predominantly influenced by environmental forcing of their ocean habitats as adults or larvae, or both.  相似文献   

A comparison of the population genetics of Lethrinus miniatus and Lutjanus sebae from the east and west coasts of Australia: Evidence for panmixia and isolation     

Lynne van Herwerden  William J. Aspden  Stephen J. Newman  Graham G. Pegg  Leica Briskey  William Sinclair   《Fisheries Research》2009,100(2):148-155

Lethrinus miniatus and Lutjanus sebae are important commercial and recreational species of reef fish. Within Australian waters the former species is less widespread than the latter and has a discontinuous distribution, whilst the latter is continuously distributed in tropical Australian waters. The demographic attributes of these species (e.g. long life span, low rates of natural mortality) make them vulnerable to over-exploitation. Consequently, conservative harvest strategies including no-take zones for these species have been adopted by fisheries management agencies to control exploitation. Information on the genetic stock structure of these species is important for developing specific management strategies. However, little is known about genetic stock structures within and between east and west Australian populations of these species. The current study used the mitochondrial genome hypervariable region 1 (HVR1) of the control region to examine variation between two sites from both the east and west Australian coasts for each species. HVR1 for L. sebae did not differ genetically either within or between coasts (F_st < 0.018, p > 0.15) at the sites studied, suggesting a panmictic population structure. Similarly, L. miniatus did not differ significantly between sites sampled within coast. However, the west coast HVR1 for L. miniatus east and west coast populations, were discrete (F_st of at least 0.92, p < 0.0001). The degree of genetic sub-division between east and west coast populations indicates that they should be managed as discrete stocks. Further, when considering both species, the lower genetic (both haplotype and nucleotide) diversity in three of the four sites on the west coast of Australia, indicates that this region is genetically impoverished and neutrality tests suggest that selection is responsible. Consequently, west Australian populations will be less resilient to perturbations (e.g. fishing, climate change) than east Australian populations, which have higher genetic diversity.  相似文献   

Dispersal and tributary immigration by juvenile coho salmon contribute to spatial expansion during colonisation     

Joseph H. Anderson  George R. Pess  Peter M. Kiffney  Todd R. Bennett  Paul L. Faulds  William I. Atlas  Thomas P. Quinn 《Ecology of Freshwater Fish》2013,22(1):30-42

Anadromous fishes are frequently restricted by artificial barriers to movement such as dams and culverts, so measuring dispersal helps identify sites where improved connectivity could promote range expansion and population viability. We used a combination of DNA‐based parentage analysis and mark–recapture techniques to evaluate dispersal by juvenile coho salmon (Oncorhynchus kisutch) in a population in the initial stages of colonisation following installation of fish passage structures at a previously impassable dam on the Cedar River, WA, USA. The spatial distribution of individuals within maternal families revealed that dispersal was common. Among the offspring of radio‐tagged mothers, 28% were collected outside the spawning reach and dispersed up to 6.3 km (median = 1.5 km). Most juveniles captured in a tributary (Rock Creek, where few adults spawned) had immigrated from the Cedar River and represented many different families. Juvenile dispersal therefore provided a secondary phase of spatial expansion following initial colonisation by adults. Consistent with the condition‐dependent dispersal hypothesis, juveniles that dispersed farther upstream in the tributary were larger than fish collected near the tributary mouth. Overall, the results demonstrated widespread dispersal in a system with low coho salmon densities, and this might increase the rate of population growth if it reduces the effects of local density dependence. By implication, juveniles can take advantage of rearing habitats reconnected through barrier removal, even when such areas are located several kilometres from adult breeding grounds.  相似文献   

The source of autumn and spring downstream migrating juvenile Atlantic salmon in a small lowland river     

Anton T. Ibbotson  William D. Riley  William R.C. Beaumont  Alastair C. Cook  Mark J. Ives  Adrian C. Pinder  Luke J. Scott 《Ecology of Freshwater Fish》2013,22(1):73-81

Over 3 years, 32,444 age‐0 group Atlantic salmon (Salmo salar) parr tagged with passive integrated transponder tags throughout the River Frome catchment were assigned to one of three groups, nonmigrants, autumn migrants and spring smolts, depending on the detection and the timing of detection at downstream tag readers (situated 8.6 km above the tidal limit). We examined the effect of density at the time of tagging (n·m^?2), distance upstream from the tidal limit (km), fish length (mm), Fulton condition index, habitat type (divided into two types, main river and carrier), days after 1 September that each fish was tagged and year (replication) on the proportions of fish in each of the migration groups. Distance upstream from tidal limit was strongly negatively related to the proportion of autumn migrants and positively related to the proportion of spring smolts. Nonmigrants had a lower average body size than migrants, although there were no differences in the sizes of autumn migrants and spring smolts in September prior to migration. Fish density had no effect on migration strategy. A lower proportion of fish migrated as autumn migrants from the smaller carrier habitats than the main river channel. There is some evidence that those parr destined to become autumn migrants underwent a lower mortality rate during September before tagging than those destined to become spring migrants indicating possible physiological or behavioural differences between these two groups of fish at that time. More research into the factors responsible for initiating the autumn migration is required.  相似文献