Five hundred eighty red alder along a 2.16 km portion of the Little Creek riparian zone were assessed for mortality following the 2009 Lockheed Fire near Davenport, California. The study area was divided into burn severity zones and every red alder within the riparian zone was observed and assessed for mortality. Height, diameter at breast height (DBH), and age were collected on selected trees. An estimation of red alder large woody debris (LWD) input to Little Creek since a 2010 LWD survey (Smith, 2010) was calculated using average red alder tree dimensions applied to Smalian’s formula (MLNRO, 2011). The mean proportion of dead red alder in the non-burn zone and burn-zone was .11 and .45 respectively. Volume of red alder LWD in Little Creek is estimated to have increased approximately 245% since the fire. Given other factors may have played a role in red alder mortality in Little Creek, the analysis reported here supports fire also contributed to accelerated mortality of red alder established following the catastrophic debris torrent in 1955 in Little Creek. This study provides useful information regarding fire and red alder and establishes baseline conditions of the Little Creek riparian zone following the 2009 Lockheed Fire.

No description available.

Sustainable landscaping includes utilization of plants requiring few inputs. We chose four species showing potential for use in arid landscapes: Purshia mexicana, Shepherdia argentea, Shepherdia rotundifolia, and Alnus maritima. We sowed seeds of S. rotundifolia, S. argentea and P. mexicana in three substrates with various water-holding properties due to differing amounts of organic matter (OM). S. rotundifolia germination was maximized in a calcined clay (66.2%) containing no OM and had low germination (12.7 - 21.8%) in the other substrates. S. argentea germination (42.3 to 53.7%) was similar in all substrates. Poor seed quality of P. mexicana resulted in inconclusive results. Our results suggest that germination of some species is enhanced by substrates with excellent drainage properties. We also investigated effects of different rates of controlled-release fertilizer (CRF) on symbiotic nodule formation in seaside alder. We found that lower than prescribed rates of CRF enhanced nodulation without compromising nitrogen status.

1. For the first time detailed phytosociological measurements, using objective methods have been made in a large number of lowland successional stands throughout eastern Canada. 2. Soil and soil surface organic matter samples were collected on a volume-weight basis for all stands studied. An increased use of bulk-density sampling methods is advocated as they allow the conversion of all nutrient percentage and parts per million analyses to actual weights par unit area profile depth, as was done in the present work. [...]

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2007. / Härtill 5 uppsatser.

The occurrence in Scotland of arbuscular mycorrhizal fungi (AMF) infective on Alnus glutinosa and the effects on early growth of inoculation of seedlings with AMF and Frankia were investigated. AMF characteristic of G/omiw-like fungi were detected microscopically in A. glutinosa roots from mineral and loam but not from highly organic soils. Both GJomus- and Gigaspora-like fungi were detected only in roots from sandy soils. Glasshouse experiments showed that Glomus and Gigaspora species gave higher colonisation of roots, and were of higher compatibility with the host plant, than Acutelospora or Scutettospora species. Colonisation by AMF increased nodulation by Frankia and vice versa. Inoculation with AMF alone and dual inoculation with Gigaspora rosea and Frankia inhibited growth of young A. glutinosa seedlings. Initially after inoculation, AMF colonisation was poor allowing the host to meet the requirements of both developing symbioses. Mycorrhizal plants inoculated with Frankia 15 days after AMF inoculation, were under significant stress and this delayed the beneficial effects of AMF and Frankia symbiosis. Seedlings compensated for the cost of symbiosis by developing a larger, leafy shoot in a period of 25-30 days after AMF inoculation, with or with out, Frankia nodulation. A significant increase in root length and branching detected after inoculation with AMF and Frankia must impose additional energy requirements. However, the stimulation of lateral root branching that follows AMF colonisation may facilitate nutrient uptake, thus helping the plant to overcome the disadvantages of early retardation of shoot growth. Competition with adjacent plant species for below ground space may also be enhanced thus facilitating competition for growing space with other plant species. These factors may be part of a strategy that assists the survival of very young seedlings in the field. The data obtained suggest that delaying Frankia inoculation for 3-4 weeks after inoculation with selected AMF should improve the production in Scottish nurseries of robust, well nodulated and mycorrhizal seedlings.

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La sporulation est un phénomène présent chez de nombreux microorganismes, généralement impliqué dans les mécanismes de dispersion et/ou résistance en conditions environnementales défavorables. La sporulation observée chez certaines souches de Frankia (genre actinobactérien fixateur d'azote) lors de leur interaction symbiotique avec les plantes actinorhiziennes est donc paradoxale dans un contexte où la bactérie bénéficie d'une niche écologique favorable à son développement. Ces souches particulières de Frankia, dites Sp+, représentent un modèle unique de symbiote capable de sporulation au sein même des cellules de son hôte. Le rôle écologique et le sens évolutif de cette sporulation in-planta reste à ce jour peu élucidé. Les deux principaux objectifs de ce travail de thèse visent donc à (i) comprendre l'influence de la sporulation in-planta sur les capacités symbiotiques des souches Sp+, en termes d'infectivité et de compétitivité et (ii) appréhender l'impact de cette sporulation sur le fonctionnement du complexe symbiotique par une méthode de profilage métabolique. Ces travaux ont permis de confirmer les particularités symbiotiques des souches Sp+ (infectivité et compétitivité accrues) et de montrer des différences significatives dans le métabolisme primaire et secondaire du complexe symbiotique associées à la présence de spores de Frankia / Sporulation is a phenomenon present in many microorganisms, usually involved in the mechanisms of dispersion and/or resistance to unfavorable environmental conditions. Sporulation occurs in some Frankia strains (a diazotrophic actinobacteria) during their symbiotic interaction with actinorhizal plants, which is paradoxical in a context where the bacterium has a favorable ecological niche for its development. These particular Frankia strains, called Sp+, represent a unique model of symbiont capable of sporulation within the host cells. The ecological role and the evolutionary meanings of this in-planta sporulation still remain understood. The two main objectives of this thesis aimed to (i) understand the influence of in-planta sporulation on the symbiotic capacity of Sp+ strains in terms of infectivity and competitiveness and (ii) understand the impact of this sporulation on the functioning of the symbiotic complex by a metabolic profiling approach. These studies have confirmed the symbiotic characteristics of Sp+ strains (greater infectivity and competitiveness) and have shown significant differences in the primary and secondary metabolism of the symbiotic complex associated with the presence of Frankia spores

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