ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

Digitale Medien

Effects of forest fire and drought on acidity of a base-poor boreal forest stream: similarities between climatic warming and acidic precipitation (1992)

Bayley, S. E. ; Schindler, D. W. ; Parker, B. R. ; [weitere]

Springer

Biodegradation 17 (1992), S. 191-204

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 1572-9729

Schlagwort(e): fire ; climate change ; boreal forest ; stream ; sulfate ; acidity ; watershed

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Energietechnik , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft

Notizen: Abstract In a boreal forest catchment in the Experimental Lakes Area in northwestern Ontario, wildfire caused an increase in the concentrations of strong acid anions and base cations of the stream. In the naturally base-poor Northwest (NW) Subbasin, a 1980 wildfire caused exports of strong acid anions to increase more than export of base cations, causing a 2.5 fold increase in the acidity of the stream. Mean annual stream pH declined from 5.15 prior to fire to 4.76 two years after fire. Acid-neutralizing capacity (ANC), calculated as the difference between total base cations and strong acid anions, decreased to 20% of pre-fire values. Sulfate and chloride were the strong acid anions responsible for the decline in ANC, increasing four-fold. While nitrate increased eleven-fold, concentrations were too low to significantly affect ANC. There was a significant correlation between weekly sulfate concentration and base cation concentration (r 2 = 0.83) in the two years after fire. Recovery of ANC was caused by the more rapid decline in concentration of sulfate than by changes in base cations. Drought produced a similar but weaker response than fire, with increased sulfate concentrations and decreased stream pH. Climatic warming that increases drought and fire frequency would have effects that mimic the impacts of acidic precipitation (i.e. higher sulfate concentrations and acidic stream waters). Areas which have higher concentrations of stored S from past acid precipitation or have large areas of peatlands in the watershed may have aggravated losses of S and H+ after drought and fire.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00004041

Permalink

	Standort	Signatur	Erwartet	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Volltext

2

Digitale Medien

The structures of fully eutectic aluminium-silicon alloy castings (1990)

Abbott, T. B. ; Parker, B. A.

Springer

Journal of materials science 25 (1990), S. 2100-2106

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 1573-4803

Quelle: Springer Online Journal Archives 1860-2000

Thema: Maschinenbau

Notizen: Abstract Strontium-modified aluminium alloys containing 14 to 15 wt% silicon were cast with fully eutectic structures by using heated moulds and high-purity materials. In alloys containing the additional elements magnesium, copper or nickel, a distinct eutectic colony structure was evident outlined by intermetallic compounds. At the edges of the castings the eutectic colony structures and the aluminium grains (revealed by anodizing) were of a similar scale. Further from the mould walls the eutectic colonies contained several aluminium grains. This is believed to result from the blocking of growth of the aluminium phase by the silicon phase.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF01045772

Permalink

	Standort	Signatur	Erwartet	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Volltext

3

Digitale Medien

The location of major genes and associated quantitative trait loci on chromosome arm 5BL of wheat (1992)

Miura, H. ; Parker, B. B. ; Snape, J. W.

Springer

Theoretical and applied genetics 85 (1992), S. 197-204

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 1432-2242

Schlagwort(e): Wheat ; Chromosome 5BL ; Major genes ; Quantitative trait loci

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Summary Chromosome 5B of bread wheat is known to carry two major genes giving rise to genetic disorders, Ne1 for hybrid necrosis and Vg for winter variegation. Additionally, in many european winter wheat varieties this chromosome is represented in a translocated form, with 5BL-7BL, 5BL-7BS chromosomes rather than the normal 5B and 7B forms of the standard variety Chinese Spring. Genetic analysis has been carried out to map these genes and the translocation break point, and to investigate their pleiotropic effects or those of linked quantitative trait loci (qtl) for economically important characters. This was facilitated by the development of single chromosome recombinant lines between a normal and translocated karyotype, and growing these in field experiments over two seasons. There was differential segregation in favour of the translocated karyotype in the population of recombinant lines. Linkage analysis revealed that the two morphological markers and the isozyme locus Ibf-B1 were located on the long arm of 5B with a gene order of: breakpoint — Ne1 — Vg — Ibf-B1. Analysis of quantitative characters using these genes as landmarks showed pleiotropic effects of Ne1 or effects of tightly linked qtl on most of the quantitative characters related to grain yield. An additional qtl determining spikelet and grain number/ear appeared to be linked to the centromere. Effects on ear emergence time were associated with both Ne1 and Vg, and these interacted with environments. Similarly, effects on plant height were associated with Ne1 and Vg. In addition, there was a further unlocated locus (loci) for height acting independently of the markers.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00222860

Permalink

	Standort	Signatur	Erwartet	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Volltext

4

Digitale Medien

Natural and man-caused factors affecting the abundance and cycling of dissolved organic substances in precambrian shield lakes (1992)

Schindler, D. W. ; Bayley, S. E. ; Curtis, P. J. ; [weitere]

Springer

Hydrobiologia 229 (1992), S. 1-21

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 1573-5117

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Abstract Effects of natural factors (drought and forest fire), and experimental perturbations (fertilization and acidification) on dissolved organic carbon (DOC) concentrations and ratios to other nutrients in lakes of the Experimental Lakes Area are examined using data obtained over a period of 20 years. DOC concentration, and the ratio of dissolved iron to DOC in lakes of the area were strongly correlated with the relative size of the catchment to the lake. DOC in many lakes of the area declined over 20 years, due to increased water residence times caused by increasing average temperature and decreasing precipitation. Inexplicably, Lake 382 was an exception to this general observation. Acidification of Lake 302S to below pH 5.0 also caused DOC to decrease. The lesser acidification of Lake 223 (min. pH 5.0) did not significantly affect DOC. Experimental acidification of a small peatland also caused a temporary decline in DOC concentrations in bog pools. Changes in DOC appear to affect the availability of mercury for methylation. Addition of aluminum to a small acidic lake caused a two-fold decline in DOC. Fertilization of Lake 227 caused a considerable increase in DOC, and in ratios of DOC to other carbon fractions. New stable ratios did not occur for a decade after fertilization began. Lake 226N, fertilized at a lower rate, showed similar but less pronounced increases in DOC, but the experiment was terminated after only eight years. Phosphorus fertilization caused a dramatic increase in the lability of the DOC pool in Lake 226N, where the autochthonous carbon pool was labelled with DI14C. A large increase in autochthonous production of DOC and increased microbial utilization of allochthonous DOC appear to have occurred. DOC concentrations in streams were higher after drought, but concentrations were unrelated to flow volume during wet periods. Due to lower streamflows in drought years, annual yields of DOC from streams were unaffected by drought. Mesocosm experiments showed that DOC's primary effect on iron is to inhibit sedimentation, possibly by suppressing flocculation reactions that are known to control the cycles of many metals. The changes in DOC in lakes brought about by changes in water renewal, acidification, or other perturbations can have major effects on the cycles of metals, lake transparency, and phytoplankton production and standing crop.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00006987

Permalink

	Standort	Signatur	Erwartet	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Volltext

5

Digitale Medien

Evolution and variability of the ITCZ in the SW Indian Ocean: 1988–90 (1994)

Jury, M. R. ; Parker, B. ; Waliser, D.

Springer

Theoretical and applied climatology 48 (1994), S. 187-194

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 1434-4483

Quelle: Springer Online Journal Archives 1860-2000

Thema: Geologie und Paläontologie , Physik

Notizen: Summary The structure and variability of the inter-tropical convergence zone (ITCZ) in the SW Indian Ocean in the austral summer is investigated. The ITCZ is identified by satellite microwave (SSMI) precipitable water (PW) values 〉 5 g cm−2, minimum outgoing longwave radiation (OLR) values 〈 220 W m−2 and the pattern of convergence in the low level (850 hPa) winds. According to OLR climatology, the ITCZ lies over 15°S latitude to the west of Madagascar (40–50°E), but near 10°S to the east of 60°E. Inter-annual and intra-seasonal variability is induced by the interaction of the convective NW monsoon and subsident easterly trades. Symptoms of the structure and variability are presented using tropical cyclone (TC) tracks, axes of PW exceedences and OLR, 850hPa wind and PW fields in the period 1988–1990. The shape and intensity of the ITCZ is modulated by the strength of the NW monsoon off east Africa and by standing vortices in the SW Indian Ocean. The topography of Madagascar imparts a distinctive break in convective characteristics, and distinguishes the SE African ITCZ from its maritime counterpart.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00867048

Permalink

	Standort	Signatur	Erwartet	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Volltext

6

Digitale Medien

Parasitoids in low-level populations ofLymantria dispar [Lep.: Lymantriidae] in different forest physiographic zones (1993)

Skinner, Margaret ; Parker, B. L. ; Wallner, W. E. ; [weitere]

Springer

BioControl 38 (1993), S. 15-29

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 1573-8248

Schlagwort(e): Insecta ; gypsy moth ; parasitism ; low-level host populations ; Compsilura concinnata

Quelle: Springer Online Journal Archives 1860-2000

Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft

Beschreibung / Inhaltsverzeichnis: Résumé Une étude a été menée pendant 2 ans sur la distribution des parasitoïdes deLymantria dispar (L.) dans une forêt du Vermont, dans la zone mésique, dans la zone de transition adjacente d'altitude plus élevée et dans la zone xérique. Dans chaque habitat, le parasitisme varie de 12 à 18% au cours des 2 années. Quand l'analyse est faite en fonction du stade de développement auquel l'hôte est récolté, les taux de parasitisme de plus de 40% sont observés sur les stades les plus âgés.Parasetigena silvestris (Robineau-Desvoidy) etPhobocampe disparis (Viereck) sont obtenus plus fréquemment dans l'habitat mésique alors queCotesia melanoscelus (Ratzeburg) etBlepharipa pratensis (= Sturmia scutellata) (Meigen) sont mieux représentés dans les récoltes provenant des zones xériques. Le parasitisme parCompsilura concinnata (Meigen) atteint des niveaux similaires dans les 3 habitats, cette espèce étant responsable des plus forts taux de parasitisme, qui s'élevait jusqu'à 40% dans les derniers stades en 1985. Le taux de parasitisme dû àC. concinnata a augmenté 3 à 4 fois de 1984 à 1985, alors que le parasitisme par les autres espèces diminuait.

Notizen: Abstract A 2-year study was conducted on the distribution of parasitoids of gypsy moth,Lymantria dispar (L.) (Lep.: Lymantriidae), in mesic and adjacent higher elevation transition and xeric forest habitats in Vermont (U.S.A.). In both years, overall parasitism ranged from 12–18% in each habitat. When analyzed according to the life stage at which the host was collected, parasitism rates of greater than 40% were obtained among the late instars.Parasetigena silvestris (Robineau-Desvoidy) andPhobocampe disparis (Viereck) were recovered most commonly from the mesic habitat, andCotesia melanoscelus (Ratzeburg) andBlepharipa pratensis (= Sturmia scutellata) (Meigen) were most common in collections from the xeric area. Parasitism byCompsilura concinnata (Meigen) occurred at similar levels in all three habitats, and this species was responsible for the highest parasitism rates on the site, reaching 40% among the late instars in 1985. Percent parasitism byC. concinnata increased three-four-fold from 1984 to 1985, while parasitism by other species declined.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02373135

Permalink