Drivers and trends in landscape patterns of stand-replacing fire in forests of the US Northern Rocky Mountains (1984–2010)

Context

Resilience in fire-prone forests is strongly affected by landscape burn-severity patterns, in part by governing propagule availability around stand-replacing patches in which all or most vegetation is killed. However, little is known about drivers of landscape patterns of stand-replacing fire, or whether such patterns are changing during an era of increased wildfire activity.

Objectives

(a) Identify key direct/indirect drivers of landscape patterns of stand-replacing fire (e.g., size, shape of patches), (b) test for temporal trends in these patterns, and (c) anticipate thresholds beyond which landscape patterns of burn severity may change fundamentally.

Methods

We applied structural equation modeling to satellite burn-severity maps of fires in the US Northern Rocky Mountains (1984–2010) to test for direct and indirect (via influence on fire size and proportion stand-replacing) effects of climate/weather, vegetation, and topography on landscape patterns of stand-replacing fire. We also tested for temporal trends in landscape patterns.

Results

Landscape patterns of stand-replacing fire were strongly controlled by fire size and proportion stand-replacing, which were, in turn, controlled by climate/weather and vegetation/topography, respectively. From 1984 to 2010, the proportion of stand-replacing fire within burn perimeters increased from 0.22 to 0.27. Trends for other landscape metrics were not significant, but may respond to further increases proportion stand-replacing fire.

Conclusions

Fires from 1984 to 2010 exhibited tremendous heterogeneity in landscape patterns of stand-replacing fire, likely promoting resilience in burned areas. If trends continue on the current trajectory, however, fires may produce larger and simpler shaped patches of stand-replacing fire with more burned area far from seed sources.

     

Strong increase of foliar inulin occurs in transgenic lettuce plants (Lactuca sativa L.) overexpressing the Asparagine Synthetase A gene from Escherichia coli

Transgenic lettuce (Lactuca sativa L. cv. 'Cortina') lines expressing the asparagine synthetase A gene from Escherichia coli were produced to alter the plant nitrogen status and eventually enhance growth. The relative molecular abundance of water-soluble metabolites was measured by 1H NMR in transgenic and conventional plants at early developmental stages and grown under the same conditions. NMR metabolic profiles assessed that a transgenic line and the wild-type counterpart shared the same compounds, but it also revealed side effects on the carbon metabolism following genetic modification. Concerning the nitrogen status, the amino acid content did not vary significantly, except for glutamic acid and gamma-aminobutyric acid, which diminished in the transgenics. As for the carbon metabolism, in transgenic leaves the contents of sucrose, glucose, and fructose decreased, whereas that of inulin increased up to 30 times, accompanied by the alteration of most Krebs's cycle organic acids and the rise of tartaric acid compared to nontransformed controls. Lettuce leaf inulins consisted of short oligomeric chains made of one glucose unit bound to two/four fructose units. Inulins are beneficial for human health, and they are extracted from plants and commercialized as long-chain types, whereas the short forms are synthesized chemically. Hence, lettuce genotypes with high content of foliar short-chain inulin represent useful materials for breeding strategies and a potential source for low molecular weight inulin.     

In vitro development of cyathostomin larvae from the third stage larvae to the fourth stage: morphologic characterization, effects of refrigeration, and species-specific patterns

A mixed population of equine cyathostomin (Nematoda, Strongyloidea) infective third stage larvae (L3) was cultured in vitro using a cell-free medium. Some L3 were cultured immediately after Baermann collection from fecal cultures, while others were kept in water at 4 °C for 7 days before initiating the in vitro cultures. Cultures were examined daily for viability. At days 2, 7, 14 and 21 larvae were collected for identification of developmental stage and morphological changes, using both light and scanning electron microscopy. Larvae were classified as early L3 (EL3), developing L3 (DL3), late L3 (LL3) and fourth stage larvae (L4) on the basis of morphological features. Viability remained high throughout the entire study period in cultures of both non-refrigerated (84.7%) and refrigerated (77.4%) larvae. However, viability of the non-refrigerated was significantly greater from 7 through 21 days of culture. Significant differences were also observed in the percentage of DL3 between the non-refrigerated and refrigerated larval cultures by day 7. The highest percentage of DL3 larvae (22.5%) was reached at the end of study in those larvae that were not previously refrigerated. The data suggests that prior refrigeration decreases viability and slows L3 development. At day 21 LL3 larvae were only a small percentage of the DL3: 6.9 and 5% in non-refrigerated and refrigerated cultures, respectively. Few of these larvae freed themselves from the L3 cuticle and moulted to L4 stage. Characteristics of individual species in vitro developmental patterns were determined by the molecular identification of individual larvae in pools of larvae randomly collected at days 0 and 21. Seven species (Coronocyclus coronatus, Cylicostephanus goldi, Cylicostephanus longibursatus, Cyathostomum catinatum, Cylicocyclus nassatus, Cylicocyclus ashworthi, Petrovinema poculatum) were identified in the day 0 pool. The greatest tendency to develop in vitro was shown by the genus Cylicostephanus with the species C. goldi and C. longibursatus that developed to the LL3-L4 stages. C. nassatus, C. ashworthi and C. coronatus did not progress in their development beyond the EL3 stage, while no apparent signs of development were registered for C. catinatum.     

Application of a low-cost RGB sensor to detect basil (Ocimum basilicum L.) nutritional status at pilot scale level

Precision Agriculture - In this work, basil plants were fertilized with 0, 2.5 mM and 10 mM nitrogen (with different NO3?/NH4+ ratios), and then monitored using a low-power...     

Morphological and microsatellite DNA diversity of Nigerian indigenous sheep

Background: Sheep is important in the socio-economic lives of people around the world. It is estimated that more than half of our once common livestock breeds are now endangered. Since genetic characterization of Nigerian sheep is still lacking, we analyzed ten morphological traits on 402 animals and 15 microsatellite DNA markers in 384 animals of the 4 Nigerian sheep breeds to better understand genetic diversity for breeding management and germplasm conservation. Results: Morphological traits of Uda and Balami were significantly (P < 0.05) higher than Yankasa, which were both higher than West African Dwarf (WAD) sheep. Stepwise discriminant analysis showed tail length, rump height, chest girth, ear length and chest depth as the most discriminating variables for classification. Mahalanobis distances show the least differentiation between Uda and Balami and the largest between WAD and Balami sheep. While 93.3% of WAD sheep were correctly assigned to their source genetic group, 63.9% of Yankasa, 61.2% of Balami and 45.2% of Uda were classified correctly by nearest neighbour discriminant analysis. The overall high Polymorphism Information Content (PIC) of all microsatellite markers ranged from 0.751 to 0.927 supporting their use in genetic characterization. Expected heterozygosity was high for all loci (0.783 to 0.93). Mean heterozygote deficiency across all populations (0.171 to 0.534) possibly indicate significant inbreeding (P < 0.05). Mean values for FST , FIT and FIS statistics across all loci were 0.088, 0.394 and 0.336 respectively. Yankasa and Balami are the most closely related breeds (DA = 0.184) while WAD and Balami are the farthest apart breeds (DA = 0.665), which is coincident with distance based on morphological analysis and population structure assessed by STRUCTURE. Conclusions: These results suggest that within-breed genetic variation in Nigerian sheep is higher than between-breeds and may be a valuable tool for genetic improvement and conservation. The higher genetic variability in Yankasa suggests the presence of unique ancestral alleles reflecting the presence of certain functional genes which may result in better adaptability in more agro-ecological zones of Nigeria. These genetic characteristics are potentially useful in planning improvement and conservation strategies in Nigerian indigenous sheep.     

Equine Sarcoid Associated with Cutaneous Habronemosis

Equine sarcoids are benign fibroblastic skin tumors affecting equids worldwide. Infection with bovine papillomavirus types 1 and 2 has been implicated as a major fact in the disease development; however, the cellular mechanisms underlying fibroblast transformation are still largely unknown. In the present study, a diagnosis of sarcoid was histologically assessed along with eosinophilic dermatitis. The sarcoid lesion expressed the viral oncoproteins E5 and E2, suggesting a causative role of the virus and its replication. Ribosomal DNA of the nematode Habronema muscae was also revealed in the lesion. This is the first report to describe and discuss an association of cutaneous habronemosis with equine sarcoid.     

Radiological investigation of an over 2000-year-old Egyptian mummy of a cat

A radiographical study of a cat mummy from the Egyptian collection of the National Archeological Museum in Parma, Italy was carried out in order to evaluate the content and to describe how cats were wrapped and mummified. The mummy contained the complete skeleton of a 4-5-month-old cat. Radiology revealed the position of the cat's body; it was wrapped to occupy the smallest space possible. In order to better position the cat, the ribs of the thorax were compressed cranio-caudally and the fore limbs were then positioned very close to the thorax. The hind limbs were flexed close to the lumbar spine and the tibio-tarsal joints were subluxated to allow the repositioning of the tarsal, metatarsal and phalanx bones cranio-caudally near the tibiae. A coccygeal vertebra was fractured in order to reposition the tail as close as possible to the body. Atlanto-occipital subluxation and a fracture/hole was present in the occipital region of the skull: whether this was made for draining skull contents as a mummification process and/or to euthanase the cat remains open for discussion.     

Effect of different solarizing materials on weed suppression and lettuce response

The effect of four solarizing plastic materials on weed suppression and yield response of two lettuce cultivars (‘Bacio’ and ‘Moringa’) grown during two consecutive seasons was investigated at Metaponto (40°23′N; 16°47′E; 10 m a.s.l.), southern Italy. All solarization treatments suppressed winter and summer weeds with no significant difference among the plastic materials, although biodegradable film was less efficient in controlling common purslane and common amaranth. Weed infestation at the harvest of both lettuce cultivars was not affected by the solarizing material, whereas fewer weeds were found in the plots grown with ‘Bacio’ than with ‘Moringa’. Lettuce yield in two successive growing seasons was always significantly higher in solarized plots than in nontreated control, without any statistical difference among the plastic materials. Yield and head quality of cv. ‘Bacio’ were higher than ‘Moringa’ in the first growing season, but the opposite occurred in the second crop. Soil solarization was confirmed to be effective for weed management in field lettuce crops in the Mediterranean areas, although weed suppression may be affected also by the lettuce cultivar. Choice of solarizing materials, when similarly effective on weeds and crop yield, should take into account also their cost. Low density polyethylene plastics emerged as the best choice in conventional lettuce crops as highly effective as, and less expensive than the other materials, whereas the use of biodegradable films should be limited to organic lettuce systems.     

Biological and molecular characterization of a recombinant isolate of <Emphasis Type="Italic">Watermelon mosaic virus</Emphasis> associated with a watermelon necrotic disease in Italy

The biological and molecular characterization is reported of a Watermelon mosaic virus isolate, denoted WMV-Le, associated with a necrotic phenotype of watermelon plants grown in the Provinces of Lecce and Taranto (Apulia, southern Italy). The fully sequenced WMV-Le genome consists of 10,045 nucleotides and is 99.1% similar to that of WMV-C05-270, a French isolate from melon of the WMV molecular group 3. Using recombination detection program RDP3, putative recombination breakpoints were identified close to nucleotide positions 42 to 1892, covering the 5′UTR/P1/HC-Pro region. The event represents the insertion of a sequence fragment of an isolate similar to WMV-FBR04-37 in the background of an isolate similar to WMV-FMF00-LL1. The field symptomatology was reproduced in watermelon plants grown in an experimental greenhouse but the virus induced severe symptoms also in Cucumis sativus, C. melo, Cucurbita maxima and C. pepo .     

Existence of two serological subclusters of Plum pox virus, strain M

A large-scale serological characterisation of Plum pox virus (PPV) isolates was carried out with 19 monoclonal antibodies (MAbs), including the universal MAb5B and the following strain-specific MAbs: AL (specific to PPV-M), 4DG5 (specific to PPV-D), TUV and AC (specific to PPV-C), and EA24 (specific to PPV-EA). The study involved 108 PPV isolates of different geographical origin (Albania, Bulgaria, Cyprus, Czech Republic, Egypt, France, Germany, Greece, Italy, Hungary, Moldova, Romania, Slovakia, Spain, Turkey and Yugoslavia) and hosts (almond, apricot, peach, plum and cherry). The inter- and intra-strain serological relationships of PPV isolates were evaluated by DASI-ELISA. High serological variability was detected, not only between strains, but also among isolates of the same strain. Computer-assisted analysis of serological data support the hypothesis of the existence of two distinct subclusters, denoted PPV-M₁ and PPV-M₂, which seem to prevail in Mediterranean and Eastern–Central European countries, respectively.