Incorporating Sectoral Structure into Shift–Share Analysis

The objective of this article is to present a new way to incorporate the sectoral dimension within the components of regional growth provided by the traditional shift–share analysis. The new methodology elaborates the way that the dynamics of a specific sector in a region are influenced by the performance of other sectors, the latter decomposed between national, structural, and differential effects. To illustrate this extension of the shift–share method, an application is provided using data for the Spanish region of Extremadura for the period 1990–2004. The results highlight how these new components can shed new insights into the analysis of sectoral and regional economic growth processes.     

Rehabilitation of Nothofagus pumilio forests in Chilean Patagonia: can fencing and planting season effectively protect against exotic European hare browsing?

New Forests - In forests affected by heavy fires and continuous grazing of exotic herbivorous mammal species, Nothofagus pumilio (lenga) cannot recover naturally. The main factors that hinder the...     

Sap flux – a real time assessment of health status in Norway spruce

Top dieback of Norway spruce (Picea abies), triggered by drought in 2004–2006, has been observed in Southeast Norway and trees died within four years after appearance of the first symptoms. The aim of our study was to use sap flux measurements as a diagnostic method for assessment of tree vitality. We used the heat field deformation method to monitor the sap flux density (SFD) in four pairs of healthy and declining trees in situ. To provide retrospective information on hydraulic performance of the trees we took samples for wood anatomical analysis. After felling the trees we used the modified differential translucence method (MDT) as a proxy for the SFD measurements. Healthy trees had three times higher SFD values as declining trees. In some healthy trees we detected decreasing SFD with time. The MDT method agreed with the SFD measurements. In conclusion, we detected sap flux dysfunction in declining trees and showed that the SFD reduction may occur during a short period, prior to occurrence of any visual symptoms. We suggest incorporating the SFD measurements into the repertoire of diagnostic tools in forest pathology.     

Verwendung vonLymantria dispar-Pheromon zur Kontrolle des Vorkommens und der Flugdauer vonLymantria monacha L. undLymantria dispar L.

Zusammenfassung Synthetisches Pheromon cis-7,8-epoxy-2-methyloctadecan — Disparlure — hat sich als wirksames Attraktant bei der Kontrolle des Vorkommens und der Flugdauer des SchwammspinnersLymantria dispar L. und der NonneLymantlria monacha L. bewährt.Die durch Disparlure-Lockfallen kontrollïerte Flugdauer beider Arten dauerte in den Beständen mehr als 6–7 Wochen, bei der Nonne in Böhmen bis Ende der ersten Septemberdekade, d. h. länger als früher angenommen wurde.Es wird der Gedanke geäußert, daß die Menge der Männchen jeder der beiden Arten, die unter 100 pro Lockfalle während der Flugdauer bleibt, der Latenz- periode des Schädlings entspricht.Der Gebrauch des synthetischen Pheromones bietet in der Forstpraxis die möglichkeit festzustellen, welche Abundanzwerte den verschiedenen Phasen des Massenwechsels dieser Schädlinge zukommen und ermöglicht auch die Beantwortung bisher unvollständig gelöster ökologischer Fragen besonders hinsichtlich der Latenzperiode der Schädlinge.

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Summary The synthetic pheromone cis-7,8-epoxy-2-methyloctadecan (Disparlure) has proved to be an effective attractant for examination of the occurrence and time of flight ofLymantria monacha L. andLymantria dispar L. The time of flight of both species, observed by means of traps with Disparlure, takes 6–7 weeks in central Europe. With Lymantria monacha in Bohemia it lasts almost till the middle of September, i. e. by 3–4 weeks longer than it has been stated so far. The number of 1–100 males captured in one trap (450 cm²) throughout the period of flight indicates the pest's abundance in the period of latency. The use of the synthetic pheromone enables to ascertain abundance in individual phases of the pest's buildup, also making it possible to explain some ecological problems, from the period of latency of the pest.

     

Combinations of several insecticides used for integrated control of Colorado potato beetle (Leptinotarsa decemlineata, Say., Coleoptera: Chrysomelidae)

The Colorado potato beetle (Leptinotarsa decemlineata Say.) (CPB) is the main potato pest in Croatia. The main problems in CPB control are related to a number of treatments and resistance development. In order to investigate the efficacy of combinations a reduced dose of spinosad (33% of the full doses) with the reduced doses (33% of full doses) of B.t.t., neem and pyrethrin against CPB larvae, 3-year field trials and one laboratory trial were conducted. Joint actions of the insecticides in combinations were analyzed. The CPB attack on experimental fields in all 3 years of investigation was high to moderate. In 2001 the maximum number of larvae on untreated plots was 11.7 larvae per plant, while in 2002 and 2003 it was lower, 5.5 and 6.1 larvae/plant, respectively. The efficacy obtained with a full dose of B.t.t. reached 75% in the field, and 78% in the laboratory trial. The residual efficacy of a full dose of B.t.t. lasted 7–10 days. The application of both, full and reduced doses of B.t.t., did not result in a significant yield increase. The results indicate that only one treatment with B.t.t. insecticide alone is not enough for efficient protection of potato against the attack of CPB larvae. The application of neem resulted in an efficacy of between 54 and 87.9%. The residual activity of neem was too short to ensure significant yield increase in 2 out of 3 years of the investigation. The application of a full dose of pyrethrin ensured an efficacy of between 86 and 89% with residual activity of 7–10 days. Only in the trial in 2003 significant yield increase (40% higher than untreated control) after the application of a full dose of pyrethin was recorded. The application of both, full and reduced doses of spinosad resulted in very high efficacy (over 90%), with residual activity between 10 and 20 days. The application of spinosad resulted in a significant yield increase in 2003, both in full and reduced doses, and in 2001 in the full dose (the reduced dose was not tested alone in 2001). High efficacy of the reduced dose of spinosad indicated its high biological activity and possibility for the reduction of the recommended dose. However, applications of combinations of insecticides in reduced doses (spinosad with B.t.t., neem and pyrethrin) resulted in efficacies of over 97% with residual activity of up to 21 days. Significant yield increase was noted after the application of the combinations of spinosad with B.t.t. and pyrethrin. The results of the laboratory trial confirmed the results of field trials. The joint action of insecticides was mainly described as independent synergism. It can be concluded that applied combinations are suitable in IPM in potato.     

Evaluation of the use of low-density LiDAR data to estimate structural attributes and biomass yield in a short-rotation willow coppice: an example in a field trial

Key message

LiDAR data (low-density data, 0.5 pulses m ^?2 ) represent an excellent management resource as they can be used to estimate forest stand characteristics in short-rotation willow coppice (SRWC) with reasonable accuracy. The technology is also a useful, practical tool for carrying out inventories in these types of stands.

Context

This study evaluated the use of very low-density airborne LiDAR (light detection and ranging) data (0.5 pulses m^?2), which can be accessed free of charge, in an SRWC established in degraded mining land.

Aims

This work aimed to determine the utility of low-density LiDAR data for estimating main forest structural attributes and biomass productivity and for comparing the estimates with field measurements carried out in an SRWC planted in marginal land.

Methods

The SRWC was established following a randomized complete block design with three clones, planted at two densities and with three fertilization levels. Use of parametric (multiple regression) and non-parametric (classification and regression trees, CART) fitting techniques yielded models with good predictive power and reliability. Both fitting methods were used for comprehensive analysis of the data and provide complementary information.

Results

The results of multiple regression analysis indicated close relationships (R_fit ² = 0.63–0.97) between LiDAR-derived metrics and the field measured data for the variables studied (H, D₂₀, D₁₃₀, FW, and DW). High R ² values were obtained for models fitted using the CART technique (R ² = 0.73–0.94).

Conclusion

Low-density LiDAR data can be used to model structural attributes and biomass yield in SRWC with reasonable accuracy. The models developed can be used to improve and optimize follow-up decisions about the management of these crops.

     

Widespread latent infection of Cryptostroma corticale in asymptomatic Acer pseudoplatanus as a risk for urban plantations

Sooty bark disease (SBD) caused by the pathogen Cryptostroma corticale is currently one of the risks to the population of Acer pseudoplatanus in Europe. After a number of records of symptomatic and dead trees in Prague, assessment of the latent non‐symptomatic stage of SBD was questioned as a means to forecast the health risk of the A. pseudoplatanus population. We used two methods of early detection of C. corticale in non‐symptomatic trees: cultivation from wood tissue on agar plates and a culture‐free approach based on nested PCR with newly designed species‐specific primers. The pathogen was detected in 25% of 112 examined trees from seven localities in Prague, but the disease incidence might be higher if more A. pseudoplatanus trees in Prague were included and if the crown infections were considered. The presence of C. corticale was positively correlated with discoloured wood, but its presence did not depend on the occurrence of external symptoms. Infected trees were more frequently found in groups on steep sites at higher elevations. In addition, heavier NO_x pollution combined with more paths and roads increased the incidence of C. corticale.     

Direct evidence of Hymenoscyphus fraxineus infection pathway through the petiole‐shoot junction

The symptoms of ash dieback caused by the fungus Hymenoscyphus fraxineus include wilting of the foliage followed by dieback of shoots, twigs and branches. Necroses in shoots are assumed to develop after infection through leaf petioles; however, clear evidence of this infection pathway has not yet been provided. Considering the multiple pathogen genotypes in dead ash petioles, we aimed to obtain a spatial overview of all H. fraxineus genotypes colonizing individual shoots and their corresponding petioles before leaf shedding to acquire precise information about the infection biology of H. fraxineus and its ability to cross the petiole‐shoot junction. Individual genotypes of H. fraxineus were characterized by the analysis of microsatellites using DNA extracted directly from petiole segments or cultures isolated from the segments. We detected 150 different multilocus genotypes in 10 analysed shoots and their respective petioles; the highest number of genotypes was eight for a single petiole and three for a single shoot. The genotypes of most shoot lesions were identical to particular genotypes from the proximal segments of petioles, implicating the main pathway of shoot infections. To test whether the amount of colonized substrate or intraspecific competition have an effect on successful infection, genotypes that reached the most proximal end of the petioles were scored for the number of invaded petiole segments and for the number of other H. fraxineus genotypes co‐occurring in the segments. However, the extent of colonization of the scored genotypes and intraspecific competition with other H. fraxineus strains did not influence pathogen success in entering the shoot. This study confirms that the majority of ash shoot infections are caused by genotypes of H. fraxineus originating from petioles. Compared to petioles, the frequency of shoot colonization as well as number of H. fraxineus genotypes in shoots was much lower.     

Inheritance of resistance to systemic symptom expression of Melon necrotic spot virus (MNSV) in Cucumis melo L. `Doublon'

In melon (Cucumis melo L.) a resistance mechanism to Melon necrotic spot virus (MNSV) controlled by a single recessive gene called nsv has been reported. We found that following mechanical inoculation of the virus C. melo cv. ‘Doublon’ shows only local reaction, but it does not develop any systemic symptom and the virus only can be recovered from the local lesions. This reaction could be considered as a new source of resistance to MNSV. In this work,the genetic control of this behaviour in the progenies from the cross ‘Doublon’ × ‘ANC-42’ (a susceptible line) is studied. We report two complete dominant genes, which we propose to call Melon necrotic resistance 1 (Mnr1) andMelon necrotic resistance 2 (Mnr2), controlling this character. The genetic linkage between one of these genes and nsv in the populations derived from the cross between ‘Doublon’ and ‘PMR-5’ (a resistant line) is also reported. The map distance between these two loci was estimated to be 19 cm. This revised version was published online in July 2006 with corrections to the Cover Date.