Genetic variation of Prunus avium in susceptibility to cherry leaf spot (Blumeriella jaapii) in spatially heterogeneous infected seed orchards

Cherry leaf spot (Blumeriella jaapii (Rehm) Arx.) is a very serious disease of wild cherry (Prunus avium L.), which produces premature leaf defoliation and vigor decrease. In two clonal seed orchards of P. avium naturally infected by B. jaapii, spatial heterogeneity and autocorrelation of neighbor damage caused by cherry leaf spot impeded proper analysis of the fungus incidence. The iterative spatial analysis (ISA), based on variography and kriging, was successfully used to eliminate the effect of this spatial heterogeneity in analysis of genetic variation in susceptibility to B. jaapii. Significant differences among P. avium clones were found, with moderate to high broad-sense heritability estimates. Genetic by environment interactions, although significant, were not quantitatively important. A strong relationship between leaf spot susceptibility and bud burst was found. However, other factors must be affecting the genetic variation in leaf spot susceptibility, as differences among clones remained highly significant when considering the bud burst as a covariate in the genetic model.     

Vegetation structure, floristic composition and growth characteristics of Aucoumea klaineana Pierre stands as influenced by stand age and thinning

The coastal forest of Gabon abounds in monospecific secondary Aucoumea klaineana stands derived from natural regeneration after shifting cultivation. This paper aims to describe the changes in the structure and dynamics of these stands with age. It then assesses the impact of selective thinning in the upper storey on both structural and dynamic parameters.

The experiment consisted of 34 Permanent Plots in stands from establishment to more mature stages (ca. 50 years old). Thirteen plots (17–45 years old) were thinned. More than 80% of the removal came from supernumerary dominant A. klaineana.

A. klaineana represented 60% of the total density in stands ca. 15 years old but >90% of the dominant trees in older stands. The changes with age in the floristic composition of the unthinned stands showed three successional stages during which pioneer species associated with A. klaineana (from establishment to ca. 15 years) were progressively replaced by mature forest species.

Basal area increased and density decreased with age before reaching stable values at ca. 40–45 years. Mortality was very high in young stands but decreased in the older ones. Mortality generally affected small diameter individuals in the dominated storey. Diameter and basal area increments showed that the stand growth resulted from the growth of dominant A. klaineana. Diameter increments of A. klaineana were elevated during the first years of colonisation (1.9 cm/year) and were still ca. 0.7 cm/year for 50-year-old dominant trees.

Thinning did not increase the mortality of the dominant population. It favoured the individual growth of A. klaineana. The gain was substantial for dominated trees and small dominant trees (from 60 to 100%) but was lower for large dominant trees (ca. 25–30%). Therefore, stimulation of individual growth did not compensate for the loss of basal area at the stand level.     

Morphinandienone alkaloids from Dehaasia longipedicellata

Five morphinoid alkaloids have been isolated from Dehaasia longipedicellata, namely (-) pallidine, a new alkaloid (+) pallidinine (1), (+)-milonine, (-) 8,14-dehydrosalutaridine and (-) sinoacutine.     

Relationship between root growth potential and field performance in Aleppo pine

Commercial stocks of Aleppo pine in Spain vary in quality, but there is no accepted standard for evaluating quality. A RGP test was applied to six commercial seedling stocklots at two dates (November, February) and under two test conditions (growth-chamber, greenhouse). The RGP’s predictive ability was evaluated on two contrasting sites. There was a considerable variation in the RGP depending on application date, test conditions and stock factors. The RGP results for November were correlated with each other but they did not explain outplanting performance. The February results in the growth-chamber correlated well with survival at both sites. Regression models explained survival both in the lower (R ² = 97%) and in the higher (R ² = 92%) quality sites. RGP has a valid predictive ability for this species although it is sensitive to the test conditions. In this sense, a shorter and more intensive test performed right before planting may be more reliable.     

Improving the design of long-term monitoring experiments in forests: a new method for the assessment of local soil variability by combining infrared spectroscopy and dendrometric data

Key message

Near- and mid-infrared spectroscopy allows for the detection of local patterns of forest soil properties. In combination with dendrometric data, it may be used as a prospective tool for determining soil heterogeneity before setting up long-term forest monitoring experiments.

Context

Forest soils and stands generally exhibit higher spatial heterogeneity than other terrestrial ecosystems. This variability needs be taken into account before setting up long-term forest monitoring experiments to avoid multiple interactions between local heterogeneity and the factors tested in the experiment.

Aims

We hypothesized that raw near- and mid-infrared spectra can be used as an integrated proxy of a large set of soil properties. The use of this method, in combination with dendrometric data, should provide a quick and cost-effective tool for optimizing the design of experimental forest sites.

Methods

We assessed the local soil heterogeneity at 11 experimental sites in oak and beech stands, which belong to a new forest long-term ecological research (LTER) network. We used near- and mid-infrared spectroscopy in soil and litter samples. The spectra were subjected to principal components analyses (PCA) to determine the intra-site variability of the soil and litter layers.

Results

Based on mapped PCA coordinates and basic dendrometric data, it was possible to design the experiment and minimize the interactions between the treatment layout and the tested variables. The method was validated with chemical analyses of the soil. No interaction was detected at the set-up of the experiment between the treatment layout and chemical soil properties (C, N, C/N ratio, pH, CEC, Al, Mg, P₂O₅, Fe, Mn, Na, and K).

Conclusion

Near-infrared (NIR) and mid-infrared (MIR) spectroscopy is a useful tool for characterizing the overall heterogeneity of soil chemical properties. It can be used without any preliminary calibration. In combination with dendrometric data, it provides a reliable method for optimizing LTER plots in different types of ecosystems.

     

Predicting stand damage and tree survival in burned forests in Catalonia (North-East Spain)

The study developed models for predicting the post-fire tree survival in Catalonia. The models are appropriate for forest planning purposes. Two types of models were developed: a stand-level model to predict the degree of damage caused by a forest fire, and tree-level models to predict the probability of a tree to survive a forest fire. The models were based on forest inventory and fire data. The inventory data on forest stands were obtained from the second (1989–1990) and third (2000–2001) Spanish national forest inventories, and the fire data consisted of the perimeters of forest fires larger than 20 ha that occurred in Catalonia between the 2nd and 3rd measurement of the inventory plots. The models were based on easily measurable forest characteristics, and they permit the forest manager to predict the effect of stand structure and species composition on the expected damage. According to the stand level fire damage model, the relative damage decreases when the stand basal area or mean tree diameter increases. Conversely, the relative stand damage increases when there is a large variation in tree size, when the stand is located on a steep slope, and when it is dominated by pine. According to the tree level survival models, trees in stands with a high basal area, a large mean tree size and a small variability in tree diameters have a high survival probability. Large trees in dominant positions have the highest probability of surviving a fire. Another result of the study is the exceptionally good post-fire survival ability of Pinus pinea and Quercus suber.     

Spatial patterns in mixed coniferous even-aged,uneven-aged and conversion stands

Different methodological approaches from the field of spatial statistics, the index of cluster size (ICS) and quadrat methods such as the two-term and three-term local quadrat variance (TTLQV and 3TLQV) and the new local variance (NLV) were tested to find a simple spatial measure to classify mixed coniferous uneven-aged, even-aged and conversion stands in the central Black Forest area of Germany. Altogether six stands were analysed with regularly distributed sample plots of 0.25 ha (50×50 m), each subdivided into 25 quadrats of 10×10 m. In each of the quadrats, diameter at breast height (dbh) for trees of the overstory (dbh>7 cm) was assessed and classified into three diameter classes. Height measurements were used to develop specific stand height curves for each stand and to calculate the standing volume per tree and per quadrat. The even-aged stands showed a regular distribution of the standing volume, while the conversion and uneven-aged stands were more clustered. This was detected using ICS, which proved to be a simple but very efficient measure for stand structure. The ICS also showed a highly random distribution of small and medium trees and a regular distribution of large trees of the overstory in the uneven-aged stand. Large and medium trees of one even-aged stand were also regularly distributed while conversion stands showed a regular, random or slightly clustered distribution of these trees. The more uneven the ages in the stands were, the larger were the phases detected by the NLV. The findings of the ICS were generally supported by the TTLQV and 3TLQV. The more uneven the ages in a stand were, the less clustered were the trees of different sizes of the understory. Clustering also decreased with increasing height of understory trees. The patterns detected in the investigated stands were related to the effect of different management regimes. Implications for the management of conversions stands based on the findings of the study are given.     

寄生小蜂对小青×黑杨树皮及杨圆蚧挥发油的行为反应

Four-armed airflow olfactometer was used to determining the foraging behavior ofPteroptrix longgiclava (Girault) (Hymenoptera: Aphelinidae) andEncarsia gigas (Tshumakova) (Hymenoptera: Aphelinidae) to the essential oils which emitted from the healthy bark ofPopulus pseudo-simonii×P. nigra, the infested bark injured byQuadraspidiotus gigas (Thiem & Gerneck), the body and scale of fixed 1st-instar-nymph ofQ. gigas. The results from these experiments showed that the volatile oils produced from the injured bark and from the scale of fixed 1st-instar-nymph had a higher attractive ability to female adults of the two species of wasps. The essential oil produced from the scale of the pest at dosages of 3–7 μL and the essential oil emitted by injured bark at dosages of 5–9 μL had a stronger alluring effect on the host searching behavior ofPteroptrix longgiclava. The essential oil from the body of fixed 1st-instar-nymph ofQ. gigas also had certain effect on the host locating effort ofPteroptrix longgiclava andEncarsia gigas. Those two wasps did not shown any reaction to the essential oil produced by the healthy bark of poplar. Foundation item: This paper was supported by National Natural Science Foundation of China (39970620) and the “TRAPOYT” Biography: CHI De-fu (1962-), male, Ph.D., Professor in Northeast Forestry University, Harbin 150040, P.R. China Responsible editor: Chai Ruihai