The populations and distribution of <Emphasis Type="Italic">Pieris japonica</Emphasis>, a poisonous tree protected from herbivore browsing pressure,increase slowly but steadily

Pieris japonica is a poisonous tree species that is rarely eaten by herbivorous animals, a fact that could enable the expansion of its distribution range and influence ecosystems into which it encroaches. In a regional-scale study, 300 P. japonica trees from 13 populations were sampled at the University of Tokyo Chichibu Forest, Japan, and were analyzed using 11 microsatellite markers. Genetic differentiation among the populations was low (F _ST = 0.022 and G′ _ST = 0.024). A plot (30 × 30 m) was established for a fine-scale study, in which all P. japonica trees and saplings were measured and genetically analyzed using the microsatellite markers. Using this approach, we detected 84 genotypes among the 121 P. japonica trees in the plot. A few genotypes had expanded by more than 5 m, indicating that the ability to reproduce asexually could facilitate P. japonica trees to remain in a given location. Autocorrelation analysis showed that the extent of nonrandom spatial genetic structure was approximately 7.0 m, suggesting that seed dispersal was limited. KINGROUP analyses showed that 44 genotype pairs were full siblings, 23 were half-siblings, and 40 were parent-offspring. Only 32 seedlings were observed, of which 15 had reproduced asexually. The number of P. japonica trees has been increasing gradually for more than half a century in our study areas.     

Geometric morphometric analyses of leaf shapes in two sympatric Chinese oaks: <Emphasis Type="Italic">Quercus dentata</Emphasis> Thunberg <Emphasis Type="Italic">and Quercus aliena</Emphasis> Blume (Fagaceae)

Key message

Geometric morphometric analyses (GMMs) of the leaf shape can distinguish two congeneric oak species Quercus dentata Thunberg and Quercus aliena Blume in sympatric areas.

Contexts

High genetic and morphological variation in different Quercus species hinder efforts to distinguish them. In China, Q. dentata and Q. aliena are generally sympatrically distributed in warm temperate forests, and share some leaf morphological characteristics.

Aims

The aim of this study was to use the morphometric methods to discriminate these sympatric Chinese oaks preliminarily identified from molecular markers.

Methods

Three hundred sixty-seven trees of seven sympatric Q. dentata and Q. aliena populations were genetically assigned to one of the two species or hybrids using Bayesian clustering analysis based on nSSR. This grouping served as a priori classification of the trees. Shapes of 1835 leaves from the 367 trees were analyzed in terms of 13 characters (landmarks) by GMMs. Correlations between environmental and leaf morphology parameters were studied using linear regression analyses.

Results

The two species were efficiently discriminated by the leaf morphology analyses (96.9 and 95.9% of sampled Q. aliena trees and Q. dentata trees were correctly identified), while putative hybrids between the two species were found to be morphologically intermediate. Moreover, we demonstrated that the leaf morphological variations of Q. aliena, Q. dentata, and their putative hybrids are correlated with environmental factors, possibly because the variation of leaf morphology is part of the response to different habitats and environmental disturbances.

Conclusion

GMMs were able to correctly classify individuals from the two species preliminary identified as Q. dentata or Q. aliena by nSSR. The high degree of classification accuracy provided by this approach may be exploited to discriminate other problematic species and highlight its utility in plant ecology and evolution studies.

     

Heartwood assessment of natural <Emphasis Type="Italic">Santalum album</Emphasis> populations for agroforestry development in Sri Lanka

Sandalwood (Santalum album) is developing as an important agroforestry crop in Sri Lanka. The value of S. album depends upon the oil content in the heartwood and its composition with reference to sesquiterpene alcohols cis-α-santalol and cis-β-santalol. According to the popular belief in Sri Lanka, certain S. album trees do not produce oil even after maturity. Therefore the present study was conducted to identify the presence and the variation of essential oil, its composition and the variation of growth parameters of nine distinctive S. album populations growing under different agroecological zones in Sri Lanka. According to the results, heartwood content, oil content and its constituents varied within and between the populations. It was interesting to observe that cis-α-santalol and cis-β-santalol were not detected in certain S. album trees though the oil contents of those trees were higher than the average. Heartwood content of the trees did not show a correlation with oil content, dbh and height. However, the oil content was significantly correlated with tree dbh and height. Majority of the trees (62 %) had heartwood essential oil in compliance to ISO standards; only a 31 % of the total sampled trees had the essential oil content above 2 % (w/w). Dry mountainous Badulla district had the highest percentage of trees complying the ISO standards. These findings are vital for identifying suitable sources for agroforestry propagation of S. album.     

Sprouting characteristics of <Emphasis Type="Italic">Quercus pubescens</Emphasis> Willd. and <Emphasis Type="Italic">Quercus frainetto</Emphasis> Ten. trees after a wildfire: To cut or not to cut the burned trees?

The aims of this study were to analyze the sprouting characteristics of Quercus pubescens and Q. frainetto trees after a wildfire and to recommend the appropriate silvicultural treatments in order to achieve dense sprout origin regeneration. This study was carried out in the area that was burned in a wildfire in northeastern Greece. Three years later, 140 Q. pubescens trees and 140 Q. frainetto trees were selected. Seventy trees for each species were individuals that were cut after the fire and were in the form of stumps, while 70 trees were intact top-killed trees, as a result of fire. In each stump and intact tree that was selected, various parameters were measured or counted: the diameter at the level of ground, the number of the developed sprouts (if any) and the height as well as the basal diameter of the tallest sprout, etc. Both species have similar sprouting behavior after a wildfire. Mother tree dimensions positively influenced the number of sprouts and the growth of the tallest sprout per individual. The mean height of the tallest sprout per stump, after three growing seasons from the forest fire, is high in both species (2.08 m for Q. pupescens and 2.29 m for Q. frainetto). Cut stumps had more sprouts than intact trees in both species. Forest practice, in order to maximize the sprouting of Q. pubescens and Q. frainetto trees after a forest fire, should cut the burned trees before the next growing season.     

Genetic diversity in two threatened species in Vietnam: <Emphasis Type="Italic">Taxus chinensis</Emphasis> and <Emphasis Type="Italic">Taxus wallichiana</Emphasis>

Taxus chinensis and T. wallichiana in have been threatened in their distribution areas in recent decades because of their over-exploitation and reduction and destruction of native habitats. Determining the genetic diversity in populations of the two species will provide guidelines for their protection and preservation. Two hundred and fifteen trees from six populations of T. chinensis and 150 sampled trees of T. wallichiana were sampled. Six microsatellite primer pairs selected from 16 primer pairs were used to investigate genetic variation at the population and species levels. Five yielded polymorphic alleles, and among the 13 putative alleles amplified, 11 were polymorphic (accounting for 76.33 %).Shannon’s information index (I) and percentage of polymorphic bands (PPB) (I = 0.202 and PPB = 67.22 % for T. chinensis; I = 0.217 and PPB = 65.03 % for T. wallichiana). Both species had low levels of genetic diversity (mean H _o = 0.107, H _e = 0.121 for T. chinensis; H _o = 0.095, H _e = 0.109 for T. wallichiana). Genetic differentiation among populations was higher (F _ST = 0.189) for T. chinensis and lower (0.156) for T. wallichiana, indicating limited gene flow (Nm) among populations for T. chinensis (0.68) and T. wallichiana (0.65). Variation among individuals of T. chinensis was 63.59 and 73.12 % for T. wallichiana. Thus, the threatened status of the two conifers is related to a lack of genetic diversity. All populations are isolated in small forest remnants. An ex situ conservation site should be established with a new population for these species that comprises all the genetic groups for the best chance to improve their fitness under environmental stresses.     

Mating patterns of the gum arabic tree (<Emphasis Type="Italic">Acacia senegal synonym Senegalia senegal</Emphasis>) in two different habitats

Understanding the variation of mating patterns in disturbed habitats provide insight into the evolutionary potential of plant species and how they persist over time. However, this phenomenon is poorly understood in tropical dryland tree species. In the present study, we investigated how Acacia senegal reproduces in two different environmental contexts in Kenya. Open-pollinated progeny arrays of 10 maternal trees from each environmental context were genotyped using 12 nuclear microsatellite markers. Overall, A. senegal displayed a predominantly allogamous mating pattern. However, higher multilocus outcrossing rate (tm) was found in Lake Bogoria (tm = 1.00) than in Kampi ya Moto population (tm = 0.949). Higher biparental inbreeding (t _m  ? t _s  = 0.116) and correlation of outcrossed paternity (rp = 0.329) was found in Kampi ya Moto than in Lake Bogoria population (t _m  ? t _s  = 0.074, rp = 0.055), showing the occurrence of mating among relatives. Coefficient of coancestry (Θ = 0.208) showed that full-sibs constitute about 21% of the offspring in Kampi ya Moto population compared to about 14% (Θ = 0.136) in Lake Bogoria population. The results demonstrate that low adult tree density of A. senegal may be promoting seed production through consanguineous mating and suggest that man-made disturbance can affect mating patterns of the species. Despite these mating differences, trees from both populations can contribute as seed source for conservational plans, and to support effective genetic conservation and artificial regeneration programs of A. senegal. We suggest collection of seeds from at least 42 and 63 trees in Lake Bogoria and Kampi ya Moto populations, respectively, to retain a progeny array with a total effective population size of 150.     

Ruling out genetic erosion in <Emphasis Type="Italic">Picea chihuahuana</Emphasis> Martínez

Genetic erosion has been variously defined as the loss of particular alleles, the reduction in richness of the total number of alleles, and the reduction in evenness of the frequencies of alleles in a given place within populations or across species. Picea chihuahuana Martínez is an endangered endemic species known to occur in at least 40 locations along the Sierra Madre Occidental, in the states of Durango and Chihuahua (Mexico), but covering a total area of no more than 300 ha. The total number of individuals has been estimated to be around 42,600, and the number of mature individuals may be <2500. The populations (including mature trees, saplings and seedlings) vary in size from 21 to 5546 individuals. It has been suggested that small populations may be more susceptible to loss of genetic variability via genetic erosion caused by genetic drift, endogamy depression and strong unidirectional selection. The predicted reduction and eventual disappearance of a suitable habitat for P. chihuahuana due to climatic change imposes an additional risk of extinction. The principal aim of this study was therefore to estimate genetic erosion in 14 populations of P. chihuahuana Martínez by comparing genetic diversity across diameter at breast height classes (as a proxy for age classes) by using AFLP markers and four indices of genetic diversity that are commonly applied in combination with dominant genetic markers. No evidence of genetic erosion was found in the 14 P. chihuahuana populations analyzed.     

Occurrence of <Emphasis Type="Italic">Bursaphelenchus mucronatus</Emphasis> (Nematoda; Aphelenchoididae) in France and association with <Emphasis Type="Italic">Monochamus galloprovincialis</Emphasis> (Coleoptera: Cerambycidae)

As a consequence of the recent introduction of the pine wood nematode Bursaphelenchus xylophilus in Portugal, nematodes of the genus Bursaphelenchus were looked for in various French pine forests, in trees attacked by Monochamus galloprovincialis, the vector insect of B. xylophilus, and in the insects themselves. Trap trees were felled in 12 localities distributed all over the country. Nematodes were extracted from transversal stem discs; insects emerging from the trap trees were studied. B. hellenicus, B. leoni, B. mucronatus and B. sexdentati were isolated, but not B. xylophilus. The presence of B. mucronatus and the absence of B. xylophilus were confirmed by molecular markers. B. mucronatus was isolated from several regions with an average prevalence of 19%. The infestation of M. galloprovincialis by B. mucronatus reached 26.7%. The wide distribution of B. mucronatus in France could have an effect on the extension of B. xylophilus in a case of an introduction.     

Regeneration dynamics of mixed stands of <Emphasis Type="Italic">Pinus pinaster</Emphasis> Ait. and <Emphasis Type="Italic">Pinus pinea</Emphasis> L. in Central Spain

The dynamics of mixed stands are more complex and less studied than those of monospecific stands. The objective of this work was to analyze the variables involved in seedling occurrence and seedling survival in mixed stands of Pinus pinaster and P. pinea in Mediterranean areas. From 2011 to 2016, regeneration of both species was monitored at two sites located in Central Spain. We installed 72 regeneration plots where seedling dynamics were monitored. All the trees in the study areas were measured and mapped. Additionally, we took hemispherical photographs in each regeneration plot. The average density of P. pinea seedlings over the study period was almost 20 times larger than that of P. pinaster. Our results indicate that the seedlings of both species grow under moderate light conditions. In addition, we found that the occurrence of seedlings of both species was related to the structure of the stand. P. pinea seedlings grew where the density and size of P. pinaster trees were low and where P. pinea trees provided moderately sheltered conditions, whereas the number of P. pinaster seedlings was related to under intermediate densities of P. pinaster trees. Furthermore, seedling survival was positively associated with age of the seedlings and negatively with the August average maximum temperature. The temporal continuity of mixed stands of P. pinea and P. pinaster in the study area is compromised by the observed lack of regeneration of P. pinaster.     

Morphometric study confirms the presence of only <Emphasis Type="Italic">Vatica mangachapoi</Emphasis> on Hainan Island,China

To date only one species of the genus Vatica Linn. (Dipterocarpaceae) has been identified, and a subspecies and three varieties have been reported on Hainan Island, China. However, it remained controversial whether the species was Vatica mangachapoi or a new species Vatica hainanensis, and whether the subspecies or varieties are taxonomically valid. We evaluated here morphometric variations of 133 trees collected from nine populations and herbarium specimens of Vatica spp. using 16 traits of leaf and fruit. Among these, leaf traits varied more within and among populations than did fruit traits. Four traits of ratios were more stable than directly-measured traits within and among populations. The ranges of lamina length, lamina width and height of maximum lamina width point were the greatest among the 16 traits, while number of lateral veins varied least among the 12 directly-measured traits. Measurements from all 9 populations overlapped for each morphological trait, and variation of each trait was continuous among both individuals and populations. The range of variation did not distinguish any specimen from V. mangachapoi as described in the flora of Southeast Asia. By cluster analysis, individuals of each population as well as specimens of each variety formed no distinct clusters. The published varieties thus were characterized by no distinguishing variations in comparison with the nine sampled populations. In conclusion, the new species V. hainanensis as well as the subspecies and varieties were not supported by our comparisons, and only V. mangachapoi without any subspecies or varieties occurs on Hainan Island, China.     

Genetic diversity and population structure analysis of <Emphasis Type="Italic">Pistacia</Emphasis> species revealed by <Emphasis Type="Italic">phenylalanine ammonia</Emphasis>-<Emphasis Type="Italic">lyase</Emphasis> gene markers and implications for conservation

Information on population genetic structure and crop genetic diversity is important for genetically improving crop species and conserving threatened species. The PAL gene sequence is part of a multigene family that can be utilized to design DNA marker systems for genetic diversity and population structure investigation. In the current study, genetic diversity and population structure of 100 accessions of wild Pistacia species were investigated with 78 PAL markers. A protocol for using PAL sequences as DNA markers was developed. A total of 313 PAL loci were recognized, showing 100% polymorphism for PAL markers. The PAL markers produced relatively more observed and effective alleles in Pistacia falcata and Pistacia atlantica, with a higher Shannon’s information index and expected heterozygosity in P. atlantica, Pistacia vera and Pistacia mutica. Pairwise assessment of Nei’s genetic distance and genetic identity between populations revealed a close association between geographically isolated populations of Pistacia khinjuk and Pistacia chinensis. The accessions of wild Pistacia species had more genetic relationship among studied groups of species. Analysis of molecular variance indicated 19% among-population variation and 81% within-population variation for the PAL gene based DNA marker. Population structure analysis based on PAL revealed four groups with high genetic admixture among populations. The results establish PAL markers as a functional DNA marker system and provide important genetic information about accessions from wild populations of Pistacia species.     

Response of species and stand types to snow/wind damage in a temperate secondary forest,Northeast China

Snow/wind damage is one of the important natural disturbances in forest ecosystems, especially in a montane secondary forest. However, the effects of snow/wind damage remain unclear which affects the management of these forests. Therefore, we investigated the responses of species, individual tree traits and stand structure to snow/wind damage in a montane secondary forest. Results show that, amongst the canopy trees, Betula costata exhibited the most uprooting, bending and overall damage ratio (the number of damaged stems to the total number of stems in a plot); Quercus mongolica showed the highest breakage ratio and Fraxinus mandshurica and Juglans mandshurica the least overall damage ratios. Among the subcanopy trees, Carpinus cordata, Acer mono, Acer tegmentosum and Acer pseudo-sieboldianum showed the least uprooting and breakage, and the most bending damage. A. pseudo-sieboldianum demonstrated the lowest breakage and highest bending damage ratios. These findings indicate that different species have various sensitivities to snow/wind damage. Larger trees (taller, wider crowns) tend to break and become uprooted, while smaller trees are bent or remain undamaged, suggesting that tree characteristics significantly influence the types of damage from snow and wind. Stands of Q. mongolica and B. costata had the highest damage ratios, whereas A. pseudo-sieboldianum had the lowest snapping ratio. In summary, the severity and type of snow/wind damage are related to individual tree attributes and stand-level characteristics. Therefore, selection of suitable species (e.g., shorter, smaller with deep root systems, hard wood, bending resistance and compression resistance) and appropriate thinning are recommended for planting in the montane secondary forests.     

Identification of pests and assessment of their damage on <Emphasis Type="Italic">Carapa procera</Emphasis> and <Emphasis Type="Italic">Lophira lanceolata</Emphasis> in Burkina Faso,West Africa

Nontimber forest products are a source of income for women in rural African communities. However, these products are frequently damaged by insect pests. The present study investigates the diversity and damage rates of insect pests that attack Carapa procera seeds and Lophira lanceolata fruits. The experiment was set up in western Burkina Faso and, for C. carapa, consisted of pests collected from seeds that had fallen to the ground and from stockpiled seeds. For L. lanceolata, pests were collected from fruits on the trees, and on the ground. The collected samples were sent to the laboratory to estimate the proportion of damaged seeds/fruits and rear the insects. The results showed that Ephestia spp., Tribolium castaneum, Oryzeaphilus spp., and Tenebroides mauritanicus were the pests of Carapa procera seeds and Lophira lanceolata fruits. Ephestia spp. was recorded as the main pest of both C. procera and L. lanceolata, whereas T. castaneum was only detected from seeds of L. lanceolata. For C. procera, the stocks were the most infested (29 %) by Ephestia spp. The infestation rate of fruits of L. lanceolata by Ephestia spp. on trees (31.42 ± 3.75 %) was less than the rate of fruits by T. castaneum on the ground (44.00 ± 3.5 %). The different body sizes of Ephestia spp. may indicate the occurrence of two putative species, one from C. procera and another one from L. lanceolata. This work provides important information that could contribute to the setting up of a local-scale sustainable management framework for oil tree pests in Burkina Faso and surrounding countries.     

Distribution,habitats and host plants of the cherry bark tortrix, <Emphasis Type="Italic">Enarmonia formosana</Emphasis> (Scopoli) in the Czech Republic (Lepidoptera,Tortricidae)

Distribution of the cherry bark tortrix, Enarmonia formosana (Scopoli) (=CBT) was determined by detecting the presence of their frass tubes on the trunk of rosaceous shrubs and trees throughout the Czech Republic. Tree disjunctive areas of CBT were indicated in the country. The overall distribution of CBT approximates the annual isothermes 8–9?°C and 10–11?°C, but a number of zonal exceptions were also determined. The occurrence of CBT on sweet cherry, Prunus avium (L.) was the key target association, but P. armeniaca L., P. cerasus L., P. divaricata Ledeb., P.?domestica L., P. persica L., and P. serrulata Lindley were also identified on the distributional map.     

Low within-population genetic diversity and high genetic differentiation among populations of the endangered plant <Emphasis Type="Italic">Tetracentron sinense</Emphasis> Oliver revealed by inter-simple sequence repeat analysis

Key message

Tetracentron sinense Oliver, an endangered species from China, displays a low within-population genetic diversity and high genetic differentiation among populations, and the existing populations could be divided into three conservation and management units.

Context

The endangered tree Tetracentron sinense Oliver has great value; however, little is known regarding the within-population genetic diversity and differentiation among T. sinense populations.

Aims

We examined the genetic diversity and differentiation of T. sinense wild populations, and we tested the effect of small-size population on the level of genetic diversity within these populations.

Methods

Using inter-simple sequence repeat (ISSR), we assessed the genetic variation and structure among 174 individuals from 26 natural populations of T. sinense sampled across its distribution range in China.

Results

The ISSR primers yielded 180 amplified loci (123 were polymorphic). At the species level, the percentage of polymorphic loci (PPL), Nei’s gene diversity (H), and Shannon’s information index (I) were 68.3%, 0.196 and 0.300, respectively. The average population level PPL was 20.0%, and the Na, Ne, H, and I were 1.20, 1.13, 0.076, and 0.112, respectively. AMOVA revealed high genetic differentiation among populations (52.0% of total variance, P?=?0.001), consistent with the gene differentiation coefficient (Gst?=?0.607) and gene flow (Nm?=?0.326). The 174 individuals of the 26 T. sinense populations clustered into three groups, and T. sinense geographic and genetic distance were significantly correlated.

Conclusions

T. sinense exhibited intermediate within-species genetic diversity, indicating preserved evolutionary potential. The low within-population genetic diversity and high genetic differentiation among T. sinense populations may be one of important factors causing endangerment. Three conservation units were determined based on genetic difference and structure. Inter-population introduction of individuals within units via appropriate propagation and seedling management might be an effective strategy for increasing T. sinense within-population genetic diversity and population size.

     

Efficiency of sample-based indices for spatial pattern recognition of wild pistachio (<Emphasis Type="Italic">Pistacia atlantica</Emphasis>) trees in semi-arid woodlands

The efficiency of sample-based indices proposed to quantify the spatial distribution of trees is influenced by the structure of tree stands, environmental heterogeneity and degree of aggregation. We evaluated 10 commonly used distance-based and 10 density-based indices using two structurally different stands of wild pistachio trees in the Zagros woodlands, Iran, to assess the reliability of each in revealing stand structure in woodlands. All trees were completely stem-mapped in a nearly pure (40 ha) and a mixed (45 ha) stand. First, the inhomogeneous pair correlation function [g(r)] and the Clark–Evans index (CEI) were used as references to reveal the true spatial arrangement of all trees in these stands. The sampled data were then evaluated using the 20 indices. Sampling was undertaken in a grid based on a square lattice using square plots (30 m × 30 m) and nearest neighbor distances at the sample points. The g(r) and CEI statistics showed that the wild pistachio trees were aggregated in both stands, although the degree of aggregation was markedly higher in the pure stand. Three distance- and six density-based indices statistically verified that the wild pistachio trees were aggregated in both stands. The distance-based Hines and Hines statistic (h _t ) and the density-based standardised Morisita (I _p ), patchiness (IP) and Cassie (C _A ) indices revealed aggregation of the trees in the two structurally different stands in the Zagros woodlands and the higher clumping in the pure stand, whereas the other indices were not sensitive enough.     

Symptoms and fungi associated with elm trees decline in Iran

Elm (Ulmus, Ulmaceae) is one of the most popular and important trees in urban and landscape areas in Iran. A severe decline of elm trees has recently been observed in some areas of Kerman and Shiraz cities. However, the identity of the causal agents has not yet been investigated. The purpose of this study, carried out in the years 2012–2014, was to isolate and identify fungal trunk pathogens associated with decline symptoms observed in elm trees. Samples were collected from trunks and branches of trees showing various disease symptoms and internal wood lesions. Fungal isolations were made from discolored or decayed wood tissue. In Kerman some elm trees were attacked by the beetle Aeolesthes sarta; therefore, samples were also collected from larvae and adults of beetles associated with trees showing wood damage. Fungal isolates were identified by morphological, cultural and molecular characteristics. Thirteen fungal species, Phaeoacremonium (P.) minimum, P. parasiticum, P. sicilianum, P. alvesii, P. fraxinopennsylvanicum, Spencermartinsia viticola, Dothiorella (Do.) sarmentorum, Neoscytalidium hyalinum, Diatrype (Di.) whitmanensis, Cosmospora viridescens, Phoma (Pho.) herbarum, Phellinus (Phe.) tuberculosus and Inonotus levis were identified. Phaeoacremonium parasiticum was the only species isolated from both larvae and adult beetles. Pathogenicity trials were performed on detached shoots of elm under greenhouse conditions. Dothiorella sarmentorum was the most virulent species based on the length of wood necrosis. This study is the first report of P. sicilianum, C. viridescens and Phe. tuberculosus in Iran. In addition, most of the isolated species are reported for the first time on elm trees in the world.     

Impacts of mixed litter decomposition from <Emphasis Type="Italic">Robinia pseudoacacia</Emphasis> and other tree species on C loss and nutrient release in the Loess Plateau of China

The productivity of Robinia pseudoacacia (R.p.) pure forest usually declines at the late growth stage, and reforming it into mixed forests could be a promising way to resolve this problem. When choosing a suitable tree species that can be mixed with R.p., the interspecific relationship is an important issue. Therefore, we gathered the autumn litter fall from R.p. and 10 other species from the Loess Plateau of China were mixed in dual species litterbags (R.p. + each other species) and buried them in soil for a 345 days lab decay incubation. We measured the litter mass loss and nutrient contents to determine whether the nutrient release was affected by mixed species litter decomposition. The impacts of mixed litter decomposition on macro-elements release were more obvious than on micro-elements. The litters with similar substrate quality might show variable impacts on nutrients release in mixed decomposition. The C loss and release of nutrient was improved by descending order when R.p. litter was mixed with Hippophae rhamnoides, Ulmus pumila, Populus simonii, Larix principis-rupprechtii and Quercus liaotungensis (Q.l.). But, except for Q.l., only the other species were recommended as suitable mix-plants for R.p. since promoting a high turnover of the nutrient in the litter compartment and a rapid availability for tree.     

Diversity and structural composition of species in dipterocarp forests: a study from Fasiakhali Wildlife Sanctuary,Bangladesh

Fasiakhali Wildlife Sanctuary is a protected area composed of tropical remnant rainforest that harbor substantial number of large,old Garjan(Dipterocarpus spp.)trees.The present study assessed composition,structure and diversity of the species in this protected area.A total of 32 trees species were recorded with DBH ≥ 11 cm belonging to 24 genera and 19 families.The forest is low in plant diversity as represented by Shannon–Wiener diversity and Simpson Dominance indices.Dipterocarpus turbinatus was the most dominant species with maximum relative density,frequency,dominance,and importance value index.Syzygium firmum and Tectona grandis followed in terms of dominance.The structural composition indicated higher number of individuals in the medium growth classes(41 to 511 cm DBH and 16–20 m height ranges),whereas D.turbinatus was the only species that dominated most of the growth classes.Poor stem density in lower growth classes indicated meager recruitment of regeneration which may be due to lower annual precipitation,increased grazing and encroachments.This study will help to understand the patterns of tree species composition and diversity in the remnant dipterocarp forests of Bangladesh.It will also contribute to identifying threatened plants to undertake D.turbinatus based conservation and sustainable management of the Fasiakhali Wildlife Sanctuary.     

Effects of <Emphasis Type="Italic">Verticillium nonalfalfae</Emphasis> on <Emphasis Type="Italic">Ailanthus altissima</Emphasis> and associated indigenous and invasive tree species in eastern Austria

The naturally occurring Verticillium nonalfalfae shows promise for biocontrol of the highly invasive Tree of Heaven (Ailanthus altissima), but might also bear a risk for non-target tree species. In this study, we conducted inoculations on potted seedlings of A. altissima as well as on eight indigenous and two invasive tree species associated with Tree of Heaven in Austria. Although vascular discolourations developed in all inoculated tree species, V. nonalfalfae was reisolated from Ailanthus and eight of the ten non-target-species, whereas typical disease symptoms and mortality only occurred on A. altissima. Results confirmed high susceptibility (S) of A. altissima to V. nonalfalfae but indicated tolerance (T) of Acer campestre, Acer pseudoplatanus and Quercus robur, possible resistance (PR) of Fraxinus excelsior, Populus nigra, Tilia cordata, Ulmus laevis and Ulmus minor and resistance (R) of Fraxinus pennsylvanica and Robinia pseudoacacia to this potential biocontrol agent. Results from seedling inoculations were confirmed by cursory field observations in Ailanthus-inoculated forest stands, where admixed A. campestre, A. pseudoplatanus, F. excelsior, Populus alba, R. pseudoacacia and U. laevis canopy trees remained asymptomatic, while mortality was induced in Ailanthus.