Cork oak vulnerability to fire: the role of bark harvesting, tree characteristics and abiotic factors

Forest ecosystems where periodical tree bark harvesting is a major economic activity may be particularly vulnerable to disturbances such as fire, since debarking usually reduces tree vigour and protection against external agents. In this paper we asked how cork oak Quercus suber trees respond after wildfires and, in particular, how bark harvesting affects post-fire tree survival and resprouting. We gathered data from 22 wildfires (4585 trees) that occurred in three southern European countries (Portugal, Spain and France), covering a wide range of conditions characteristic of Q. suber ecosystems. Post-fire tree responses (tree mortality, stem mortality and crown resprouting) were examined in relation to management and ecological factors using generalized linear mixed-effects models. Results showed that bark thickness and bark harvesting are major factors affecting resistance of Q. suber to fire. Fire vulnerability was higher for trees with thin bark (young or recently debarked individuals) and decreased with increasing bark thickness until cork was 3-4 cm thick. This bark thickness corresponds to the moment when exploited trees are debarked again, meaning that exploited trees are vulnerable to fire during a longer period. Exploited trees were also more likely to be top-killed than unexploited trees, even for the same bark thickness. Additionally, vulnerability to fire increased with burn severity and with tree diameter, and was higher in trees burned in early summer or located in drier south-facing aspects. We provided tree response models useful to help estimating the impact of fire and to support management decisions. The results suggested that an appropriate management of surface fuels and changes in the bark harvesting regime (e.g. debarking coexisting trees in different years or increasing the harvesting cycle) would decrease vulnerability to fire and contribute to the conservation of cork oak ecosystems.     

Lutein epoxide cycle, light harvesting and photoprotection in species of the tropical tree genus Inga

Dynamics and possible function of the lutein epoxide (Lx) cycle, that is, the reversible conversion of Lx to lutein (L) in the light-harvesting antennae, were investigated in leaves of tropical tree species. Photosynthetic pigments were quantified in nine Inga species and species from three other genera. In Inga , Lx levels were high in shade leaves (mostly above 20 mmol mol⁻¹ chlorophyll) and low in sun leaves. In Virola surinamensis , both sun and shade leaves exhibited very high Lx contents (about 60 mmol mol⁻¹ chlorophyll). In Inga marginata grown under high irradiance, Lx slowly accumulated within several days upon transfer to deep shade. When shade leaves of I. marginata were briefly exposed to the sunlight, both violaxanthin and Lx were quickly de-epoxidized. Subsequently, overnight recovery occurred only for violaxanthin, not for Lx. In such leaves, containing reduced levels of Lx and increased levels of L, chlorophyll fluorescence induction showed significantly slower reduction of the photosystem II electron acceptor, Q _A, and faster formation as well as a higher level of non-photochemical quenching. The results indicate that slow Lx accumulation in Inga leaves may improve light harvesting under limiting light, while quick de-epoxidation of Lx to L in response to excess light may enhance photoprotection.     

Karyotypes and sex determination of ten species of phytoseiid mites (acarina: Mesostigmata)

The chromosomal picture was studied on early cleayage divisiona of 10 phytoseiid mites, using the aceto-orcein smear technique. Eggs of 9 species have either a haploid (4) or a diploid (8) number of chromosomes:Amblyseius rubini Swirski & Amitai,A. swirskii Athias,A. hibisci Chant,A. ohilenensis (Dosse),A. largoensis (Muma),Typhlodromus athiasae Porath and SwirskiT. rhenanus (Oud.) sensu latiore,Phytoseiulus persimilis Athias, andI phiseius degeneraus (Berlese).Typhlodromus oceidentalis Nesbitt has 3 and 6 chromosomes. In sections and smears of post embryonic stages belonging to mites representative of the four genera, a haploid number was found in males, whereas in females somatic cells contained 2n and ovaries n as well as 2n. Thus it is shown that sex is determined by the haplo-diploid (arrhenotokous) mechanism. Males differ from females in the structure of the interphase nuclei belonging to the central nervous system. Contribution from The Volcani Institute of Agricultural Research (NUIA.) Bet Dagan, Israel, 1968 Series, No. 1331-E.     

New species of bark beetles from the Rovno amber (Insecta: Coleoptera: Scolytidae)

Two new species of bark beetles are described from the Late Eocene Rovno amber. Xylechinus mozolevskae sp. nov. (Hylesininae: Tomicini) is the first fossil representative of this genus, differing from recent species in having large triangular scales along the suture. Taphramites rovnoensis sp. nov. (Scolytinae: Dryocoetini) differs from the closest species, T. gnathotrichus from Baltic amber, in the presence of short thin hairs on the elytra.     

A species tree for the Australo-Papuan Fairy-wrens and allies (Aves: Maluridae)

We explored the efficacy of species tree methods at the family level in birds, using the Australo-Papuan Fairy-wrens (Passeriformes: Maluridae) as a model system. Fairy-wrens of the genus Malurus are known for high intensities of sexual selection, resulting in some cases in rapid speciation. This history suggests that incomplete lineage sorting (ILS) of neutrally evolving loci could be substantial, a situation that could compromise traditional methods of combining loci in phylogenetic analysis. Using 18 molecular markers (5 anonymous loci, 7 exons, 5 introns, and 1 mitochondrial DNA locus), we show that gene tree monophyly across species could be rejected for 16 of 18 loci, suggesting substantial ILS at the family level in these birds. Using the software Concaterpillar, we also detect three statistically distinct clusters of gene trees among the 18 loci. Despite substantial variation in gene trees, species trees constructed using four different species tree estimation methods (BEST, BUCKy, and STAR) were generally well supported and similar to each other and to the concatenation tree, with a few mild discordances at nodes that could be explained by rapid and recent speciation events. By contrast, minimizing deep coalescences produced a species tree that was topologically more divergent from those of the other methods as measured by multidimensional scaling of trees. Additionally, gene and species trees were topologically more similar in the BEST analysis, presumably because of the species tree prior employed in BEST which appropriately assumes that gene trees are correlated with each other and with the species tree. Among the 18 loci, we also discovered 102 independent indel markers, which also proved phylogenetically informative, primarily among genera, and displayed a ～4-fold bias towards deletions. As suggested in earlier work, the grasswrens (Amytornis) are sister to the rest of the family and the emu-wrens (Stipiturus) are sister to fairy-wrens (Malurus, Clytomyias). Our study shows that ILS is common at the family level in birds yet, despite this, species tree methods converge on broadly similar results for this family.     

Ophiostoma species (Ascomycetes: Ophiostomatales) associated with bark beetles (Coleoptera: Scolytinae) colonizing Pinus radiata in northern Spain

Bark beetles (Coleoptera: Scolytinae) are known to be associated with fungi, especially species of Ophiostoma sensu lato and Ceratocystis. However, very little is known about these fungi in Spain. In this study, we examined the fungi associated with 13 bark beetle species and one weevil (Coleoptera: Entiminae) infesting Pinus radiata in the Basque Country of northern Spain. This study included an examination of 1323 bark beetles or their galleries in P. radiata. Isolations yielded a total of 920 cultures, which included 16 species of Ophiostoma sensu lato or their asexual states. These 16 species included 69 associations between fungi and bark beetles and weevils that have not previously been recorded. The most commonly encountered fungal associates of the bark beetles were Ophiostoma ips, Leptographium guttulatum, Ophiostoma stenoceras, and Ophiostoma piceae. In most cases, the niche of colonization had a significant effect on the abundance and composition of colonizing fungi. This confirms that resource overlap between species is reduced by partial spatial segregation. Interaction between niche and time seldom had a significant effect, which suggests that spatial colonization patterns are rarely flexible throughout timber degradation. The differences in common associates among the bark beetle species could be linked to the different niches that these beetles occupy.     

Electrophoretic and morphological comparisons in ten rain forest species of Shorea (Dipterocarpaceae)

Differences identified by electrophoretic separation of enzymes and other proteins are providing increasing informative for the study of evolutionary affinities within a genus. Zymogran compared with a scheme of putative affinities derived from a standard taxonomic classi based on consciously weighted morphological characters, as well as with indices of similarity on an array of morphological criteria relating to twigs, stipules, leaves, inflorescences and structure for 10 species of Shorea from southeast Malaysia. Shorea ovalis is placed in a separate of the genus from the other nine species; S. leprosula, S. parviflia and S. curtisii are related other on R^p data and a high degree of similarity is shown between these three spec S. dasyphylla .     

Spermiogenesis and sperm ultrastructure in ten species of Loricariidae (Siluriformes, Teleostei)

The current study describes the ultrastructural characteristics of spermatogenesis, spermiogenesis, and spermatozoa in specimens of siluriform taxa Neoplecostominae, Hypoptopomatinae, Otothyrinae, Loricariinae, and Hypostominae. Our data show that the characteristics of spermatogenesis and spermiogenesis and spermatozoa ultrastructure of Neoplecostominae are more common to Hypoptopomatinae and Otothyrinae than to Loricariinae and Hypostominae. Furthermore, Loricariinae and Hypostominae have more characteristics in common than with any other group of Loricariidae. These data reinforce the phylogenetic hypotheses of relationships among the subfamilies of Loricariidae. Considering the available data in Loricarioidei, Loricariidae presents ultrastructural characteristics of spermatogenesis and spermiogenesis that are also observed in Astroblepidae, its sister group. However, the most of the characteristics of spermatozoa ultrastructure found in Astroblepidae are also observed in Scoloplacidae, the sister group of a clade composed of Astroblepidae and Loricariidae.     

Millipede (Diplopoda) communities in an arboretum: Influence of tree species and soil properties

The paper deals with the influence of tree species on millipede communities (Diplopoda). The research was carried out in nine sites in the Borová hora arboretum (Zvolen town, Central Slovakia). Each studied site represents a monoculture of one of nine tree species: Betula pubescens Ehrh., Pinus sylvestris L., Larix decidua Mill., Carpinus betulus L., Abies alba Mill., Picea abies (L.) Karst., Alnus incana (L.) Moench, Populus nigra L., Ulmus laevis Pall. Millipedes were collected by pitfall trapping during vegetation periods in 2008-2011. In total, 1064 individuals of 17 species and 7 families were obtained. The results of research confirmed (i) an influence of tree species on the composition of millipede communities, (ii) a significant influence of soil nitrogen on the species richness and biodiversity, and (iii) an impact of soil pH on the species composition of these terrestrial invertebrate communities. In terms of total dynamic activity and species richness of millipedes, the most favourable conditions were revealed in the forest stands of Alnus incana, Populus nigra, Ulmus laevis and Carpinus betulus. On the contrary, the least favourable biotopes were (from both points of view) the forest stands of Betula pubescens and Larix decidua.     

Niche breadth and resource partitioning by four sympatric species of bark beetles (Coleoptera: Scolytidae)

Summary In a North Carolina population of Diamorpha smallii, densities were artificially manipulated by thinning stands to predetermined densities. Individuals in areas of high density produce fewer seeds than individuals at low density in the same habitat. Three components of fecundity, the number of flowers per plant, the number of fruits per plant, and the number of seeds per fruit, were negatively correlated with density. The relationship of components of fecundity to density were used to develop a model of population regulation for this species. These results and predictions from the model are discussed in relation to other density studies.     

Morphactin transport and metabolism in tree bark tissues: comparative studies in vitro

Bark banding of morphaction is an effective means of controling stem elongation in Pinus radiata D. Don (Monterey pine) but not Juglans regia L. (English walnut). Diffusion coefficients of ¹⁴C-labeled morphactin across excised disks of tree bark, measured in specially designed diffusion chambers, were 11 to 85 fold greater in pine than walnut. In seedlings of comparable age, the suberin layer of walnut bark is much thicker than that of pine; if the layer is removed, diffusion of ¹⁴C-morphactin is enhanced 39-fold in pine and 285-fold in walnut. Morphactin applied to the bark as an ester is rapidly hydrolyzed to its carboxylic acid derivative in both pine and walnut. This conversion occurs rapidly in the bark of both species and does not appear to limit the rate of morphactin movement across the bark. These results suggest that diffusion across the suberin layer and not metabolism limits morphactin transport across the bark.     

The tree Cedrela odorata (Meliaceae): a morphologically subdivided species in Costa Rica

In Latin America. Cedrela odorata is a wide ranging species that occurs in several environments, where it shows significant morphological variation. A common garden experiment was established with seedlings from 63 families of ten populations from two habitat types (mesic and dry), distributed throughout Costa Rica, to examine the relationships between quantitative variation and site of population origin. Seedlings from dry areas tended to be distinct from those from mesic areas, with climatic grouping of provenance explaining a mean of 52% of the total variance and 80% of the genetic variance. Cluster analysis for seedling traits showed two natural groupings of families, which corresponded for the most part with the regional population groupings into mesic (Atlantic and South Pacific) and dry (North Pacific) groups. Cluster analysis based on seed weight and size also separated populations into mesic and dry climatic groups. Seeds from populations in dry areas were 43% heavier, and seedlings were 61% taller, 117% greater in diameter, and with leaflets 39% longer and 81% wider. These differences may be related to fast growth in the dry zone for taking advantage of early life cycle moisture availability. These findings may indicate incipient speciation in C. odorata in Costa Rica. Evaluation of reproductive isolating mechanisms between populations from the mesic and dry zones, and of clines at potential zones of hybridization would assist in testing a speciation hypothesis.     

Optimizing a basal bark spray of dinotefuran to manage armored scales (Hemiptera: Diaspididae) in Christmas tree plantations

The armored scales Fiorinia externa Ferris and Aspidiotus cryptomeriae Kuwana (Hemiptera: Diaspididae) are increasingly damaging to Christmas tree plantings in southern New England. The systemic insecticide dinotefuran was investigated for selectively suppressing armored scale populations relative to their natural enemies in cooperating growers' fields in 2008 and 2009. Banded soil application of dinotefuran resulted in poor control. However, a dinotefuran spray applied to the basal 25 cm of trunk resulted in its absorption through the bark, translocation to the foliage, and good efficacy. The basal bark spray did not significantly impact the activity of predators Chilocorus stigma (Say) or Cybocephalus nipponicus Enrody-Younga and in 2009 showed a dosage-dependent improvement in the percentage of scales parasitized by Encarsia citrina Craw. A field dosage-response factorial experiment revealed that a 0.25% (vol:vol) addition of a surfactant with dinotefuran did not enhance insecticidal effect. Probit-transformed scale population reduction relative to the untreated check was subjected to linear regression analysis; reduction of scale populations was proportional to the log of insecticide dosage, whereas basal bark spray efficacy declined in proportion to the cube of tree height. The regression equation can be used to optimize dosage relative to tree height. Excellent efficacy resulted from basal bark spray application dates of 28 April (prebud break) to mid-June, but earlier spray timing within that treatment window had fewer crawlers discoloring new growth with their short-lived feeding. A basal bark spray of dinotefuran is well suited for integration with natural enemies to manage armored scales in Christmas tree plantations.     

Molecular cloning of the bark and seed lectins from the Japanese pagoda tree (Sophora japonica)

cDNA clones encoding the bark and seed lectins from Sophora japonica were isolated and their sequences analyzed. Screening of a cDNA library constructed from polyA RNA isolated from the bark resulted in the isolation of three different lectin cDNA clones. The first clone encodes the GalNAc-specific bark lectin which was originally described by Hankins et al. whereas the other clones encode the two isoforms of the mannose/glucose-specific lectin reported by Ueno et al.. Molecular cloning of the seed lectin genes revealed that Sophora seeds contain only a GalNAc-specific lectin which is highly homologous to though not identical with the GalNAc-specific lectin from the bark. All lectin polypeptides are translated from mRNAs of ca. 1.3 kb encoding a precursor carrying a signal peptide. In the case of the mannose/glucose-specific bark lectins this precursor is post-translationally processed in two smaller peptides. Alignment of the deduced amino acid sequences of the different clones revealed striking sequence similarities between the mannose/glucose-binding and the GalNAc-specific lectins. Furthermore, there was a high degree of sequence homology with other legume lectins which allowed molecular modelling of the Sophora lectins using the coordinates of the Pisum sativum, Lathyrus ochrus and Erythrina corallodendron lectins.     

Relationship between the timing of vessel formation and leaf phenology in ten ring-porous and diffuse-porous deciduous tree species

The goal of this study is to clarify how different aspects of plant function are coordinated developmentally for species of ring-porous versus diffuse-porous deciduous trees, comparing the timing of leaf phenology and vessel formation in twigs and stems from an ecophysiological viewpoint. Cylindrical stem cores and twigs were collected at intervals from early spring through summer from five ring-porous and five diffuse-porous species in a cool temperate forest, and leaf and vessel formation were observed simultaneously. We found that the first-formed vessels of the year were lignified in twigs around the time of leaf appearance and at or before full leaf expansion of each tree in both groups of species with flush-leaves. Vessels in stems were lignified 2 weeks before to 4 weeks after leaf appearance and before or around full leaf expansion of the tree in ring-porous species. This was significantly earlier than in diffuse-porous species, in which stem vessel lignification was 2–8 weeks after leaf appearance and at or after full leaf expansion of the tree. The timing of vessel formation in twigs compared to stems was significantly earlier in ring-porous species than in diffuse-porous species. Lignification of vessels in stems occurred within 2 weeks of lignification in the twigs of ring-porous species and 2–8 weeks after lignification in twigs of diffuse-porous species. These results indicate the order and time-lag of leaf and vessel formation. Ring-porous species showed intensive leaf/vessel production, whereas diffuse-porous species showed less intensive leaf/vessel production.     

Field experiments on seed dispersal by wind in ten umbelliferous species (Apiaceae)

This report presents data from experiments on seed dispersal by wind for ten species of the family Apiaceae. Seed shadows were obtained in the field under natural conditions, using wind speeds between four and ten m/s. The flight of individual seeds was followed by eye, and seed shadows were acquired, with median distances varying from 0.7 to 3.1 m between species. Multiple regression models of wind speed and seed weight on dispersal distance were significant for six out of ten species; wind speed had significant effects in seven cases, but seed weight only once. A good correlation between mean terminal falling velocity of the seeds of a species and median dispersal distance, indicates the promising explanatory power that individual terminal velocity data might have on dispersal distance, together with wind speed and turbulence. The theory that seeds that seem to be adapted to wind dispersal travel much longer distances than seeds that have no adaptation was tested. Flattened and winged seeds were indeed found to be transported further by wind, but not much further. Moreover, the species with wind-adapted seeds were also taller, being an alternative explanation since their seeds experienced higher wind speeds at these greater heights. Furthermore, flattened and winged seeds were disseminated from ripe umbels at lower wind speeds in the laboratory. This means that the observed difference in dispersal distance would have been smaller when species specific thresholds for wind speed were incorporated in the field experiments. We argue therefore, that seed morphology is not always the best predictor in classifying species in groups with distinctly different dispersal ability.